BRUSHLESS DC MOTOR DRIVE CONTROLLED BY MICRO CONTROLLERProject report submitted in partial fulfillment of the requirements For the award of the degree of BACHELOR OF TECHNOLOGY IN ELECTRICAL AND ELECTRONICS ENGINEERING By MD.ABDUL BASID (08241A0256) K.DHANASEKHA R REDDY (08241A026 5) B.RAMAKRISHNA (08241A0289) P.SRAVAN KUMAR (08241A02A3) Under the guidance of E.VenkateswarluAssistant Professor Department of Electrical and Electronics Engineering GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING & TECHNOLOGY, BACHUPALLY, HYDERABAD-72 2012
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DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING
C E R T I F I C T E
This is to certify that the project report entitled “BRUSHLESS DC MOTOR DRIVE
CONTROLLED BY MICROCONTROLLER ” that is being submitted by Mr. MD.
ABDUL BASID, K.DHANASEKHAR REDDY, B.RAMAKRISHNA and P.SRAVAN
KUMAR in partial fulfillment for the award of the Degree of Bachelor of Technology in
Electrical and Electronics Engineering to the Jawaharlal Nehru Technological University is arecord of bonafide work carried out by him under my guidance and supervision. The results embodied inthis project report have not been submitted to any other University or Institute for the award of anygraduation degree.
AbstractA DC Brushless Motor uses a permanent magnet external rotor, three phases of driving coils, oneor more Hall effect devices to sense the position of the rotor, and the associated drive electronics.The coils are activated, one phase after the other, by the drive electronics as cued by the signalsfrom the Hall effect sensors, they act as three-phase synchronous motors containing their
own variable frequency drive electronics.
The following are properties of BLDC Motor
Electronic commutation based on Hall position sensors Less required maintenance due to absence of brushes Speed/Torque- flat, enables operation at all speeds with rated load High efficiency, no voltage drop across brushes High output power/frame size.
Reduced size due to superior thermal characteristics. Because BLDC has the windings onthe stator, which is connected to the case, the heat disipation is better
Higher speed range - no mechanical limitation imposed by brushes/commutator Low electric noise generation
LIST OF TABLES1. Table-1.1 Comparison of BLDC and PMSM motors2.Table-2.1:Advantages and Disadvantages of different types of motor3. Table-2.2: Characteristic between a DC, BLDC and an Induction motor
4. Table -5.1 Valid Switch states for a three phase VSI
The economic constraints and new standards legislated by governments place increasingly stringentrequirements on electrical systems. New generations of equipment must have higher performance
parameters such as better efficiency and reduced electromagnetic interference. System flexibility must be high to facilitate market modifications and to reduce development time. All these improvementsmust be achieved while, at the same time, decreasing system cost.
Brushless motor technology makes it possible to achieve these specifications. Such motors combinehigh reliability with high efficiency, and for a lower cost in comparison with brush motors. This paperdescribes the use of a Brushless DC Motor (BLDC). Although the brushless characteristic can be applyto several kinds of motors – AC synchronous motors, stepper motors, switched reluctance motors, ACinduction motors - the BLDC motor is conventionally defined as a permanent magnet synchronousmotor with a trapezoidal Back EMF waveform shape. Permanent magnet synchronous machines withtrapezoidal Back-EMF and (120 electrical degrees wide) rectangular stator currents are widely used as
they offer the following advantages first, assuming the motor has pure trapezoidal Back EMF and thatthe stator phases commutation process is accurate, the mechanical torque developed by the motor isconstant; secondly, the Brushless DC drives show a very high mechanical power density
1.1 BLDC MOTORS:
The BLDC motor is an AC synchronous motor with permanent magnets on the rotor (moving part) andwindings on the stator (fix part). Permanent magnets create the rotor flux and the energizedstator windings create electromagnet poles. The rotor (equivalent to a bar magnet) is attracted by theenergized stator phase. By using the appropriate sequence to supply the stator phases, a rotating field
on the stator is created and maintained. This action of the rotor - chasing after the electromagnet poleson the stator - is the fundamental action used in synchronous permanent magnet motors. The lead between the rotor and the rotating field must be controlled to produce torque and this synchronizationimplies knowledge of the rotor position.
Fig.1.1 A three-phase synchronous motor with a one permanent magnet pair pole rotor
On the stator side, three phase motors are the most common. These offer a good compromise between precise control and the number of power electronic devices required to control the stator currents. Forthe rotor, a greater number of poles usually create a greater torque for the same level of current. On theother hand, by adding more magnets, a point is reached where, because of the space needed
between magnets, the torque no longer increases. The manufacturing cost also increases with the
number of poles. As a consequence, the number of poles is a compromise between cost, torque andvolume.
Permanent magnet synchronous motors can be classified in many ways, one of these that is of particular interest to us is that depending on back-emf profiles: Brushless Direct Current Motor(BLDC) and Permanent Magnet Synchronous Motor (PMSM). This terminology defines the shape ofthe back-emf of the synchronous motor. Both BLDC and PMSM motors have permanent magnets onthe rotor but differ in the flux distributions and back-emf profiles. To get the best performance out ofthe synchronous motor, it is important to identify the type of motor in order to apply the mostappropriate type of control as described in the next chapters.
1.2 COMPARISION OF BLDC AND PMSM:
Table 1.1 Comparison of BLDC and PMSM motors
BLDC PMSM
Synchronous machine Synchronous machine
Fed with direct currents Fed with sinusoidal currents
Trapezoidal Bemf Sinusoidal Bemf
Stator Flux position commutation each 60 Continuous stator flux position variation
Only two phases ON at the same time Possible to have three phases ON at the same
Torque ripple at commutations No torque ripple at commutations
Low order current harmonics in the audible Less harmonics due to sinusoidal excitation
Higher core losses due to harmonic content Lower core loss
Less switching losses Higher switching losses at the same switching
Control algorithms are relatively simple Control algorithms are mathematically intensive
motor types are synchronous machines. The only difference between them is the shape of theinduced voltage, resulting from two different manners of wiring the stator coils. The back-emf istrapezoidal in the BLDC motor case, and sinusoidal in the PMSM motor case.
machines could be driven with sinusoidal currents and PMSM with direct currents, but for better performance, PMSM motors should be excited by sinusoidal currents and BLDC machines bydirect currents.
can structure (hardware and software) of a sinusoidal motor required several current sensorsand sinusoidal phase currents were hard to achieve with analog techniques. Therefore many motors(sinusoidal like trapezoidal) were driven with direct current for cost and simplicity reasons ,compromising efficiency and dynamic behavior.
The BLDC motor is characterized by a two phase ON operation to control the inverter. In thiscontrol scheme, torque production follows the principle that current should flow in only two
of the three phases at a time and that there should be no torque production in the region of BackEMF zero crossings. The following figure describes the electrical wave forms in the BLDC motor inthe two phases ON operation.
This control structure has several advantages:
Only one current sensor is necessary
The positioning of the current sensor allows the use of low cost sensors as a shunt.
We have seen that the principle of the BLDC motor is, at all times, to energize the phase pair whichcan produce the highest torque. To optimize this effect the Back EMF shape is trapezoidal. Thecombination of a DC current with a trapezoidal Back EMF makes it theoretically possible to produce aconstant torque. In practice, the current cannot be established instantaneously in a motor phase; as aconsequence the torque ripple is present at each 60 degree phase commutation.
Fig 1.2 Electrical Waveforms in the Two Phase ON Operation and Torque Ripple
If the motor used has a sinusoidal Back EMF shape, this control can be applied but the producedtorque is:
Firstly, not constant but made up from portions of a sine wave. This is due to its being thecombination of a trapezoidal current control strategy and of a sinusoidal Back EMF. Bear in mind that a
sinusoidal Back EMF shape motor controlled with a sine wave strategy (three phase ON) produces aconstanttorque.
Secondly, the torque value produced is weaker.
Fig.1.3 Torque Ripple in a Sinusoidal Motor Controlled as a BLDC
An electric motor is an electromechanical device that converts electrical energy into mechan-ical
energy. Most electric motors operate through the interaction of magnetic fields and current-carrying conductorsto generate force. The reverse process, producing electrical energy from mechanical energy, isdone by generators such as an alternator or a dynamo; some electric motors can also be used asgenerators, for example, a traction motor on a vehicle may perform both tasks. Electric motors andgenerators are commonly referred to as electric machines. Electric motors are found in applications as diverse as industrial fans, blowers and pumps, machinetools, household appliances, power tools, and disk drives. They may be powered by direct current, e.g., a
battery powered portable device or motor vehicle, or by alternating current from a central electricaldistribution grid or inverter. The smallest motors may be found in electric wristwatches. Medium-sizemotors of highly standardized dimensions and characteristics provide convenient mechanical power forindustrial uses. The very largest electric motors are used for propulsion of ships, pipeline compressors,and water pumps with ratings in the millions of watts. Electric motors may be classified by the source ofelectric power, by their internal construction, by their application, or by the type of motion they give.The physical principle behind production of mechanical force by the interactions of an electric currentand a magnetic field, Faraday's law of induction, was discovered by Michael Faraday in 1831. Electricmotors of increasing efficiency were constructed from 1821 through the end of the 19th century, butcommercial exploitation of electric motors on a large scale required efficient electrical generators andelectrical distribution networks. The first commercially successful motors were made around 1873.Some devices convert electricity into motion but do not generate usable mechanical power as a primaryobjective, and so are not generally referred to as electric motors. For example, magnetic solenoids and
loudspeakers are usually described as actuators and transducers, respectively, instead of motors. Someelectric motors are used to produce torque or force.
2.1 DC MOTOR:
There are many different types of DC motor commonly used.
The first type is the Brushed DC electric motor . The brushed DC electric motor generates torquedirectly from DC power supplied to the motor by using internal commutation, stationary magnets or
rotating electrical magnets.There is also a brushless type k nown as Brushless DC motor which is a synchronous
electric motor that are electric motors powered by direct-current (DC) electricity and having electronic
commutation systems, rather than mechanical brushes and commutators.
A Stepper Motor is also a brushless, electric motor that can divide a full rotation into a large
number of steps. The motor's position can be controlled precisely without any feedback mechanism, as
long as the motor is carefully sized to the application. Signal pulses will drive the motor and the shaft
of the stepper motor moves between discrete positions proportional to the pulses. Steppers are
generally commutated open loop as the driver has no feedback on where the rotor actually is.
Lastly is the Servo motor. The servo motor is driven by a voltage value and the output shaft of
the servo motor is commanded to a particular angular position corresponding to the input voltage.5
They are commonly used in radio controlled airplanes to control the wing flaps and also in RC radio
cars to control the steering of the car.
2.2 AC MOTOR:
An AC motor is an electric motor driven by an alternating current.
It commonly consists of two basic parts, an outside stationary stator having coils supplied with
alternating current to produce a rotating magnetic field, and an inside rotor attached to the output
shaft that is given a torque by the rotating field.
There are two main types of AC motors, depending on the type of rotor used.
The first type is the induction motor, which runs slightly slower than the supply
frequency. The magnetic field on the rotor of this motor is created by an induced current.
The second type is the synchronous motor, which does not rely on induction and as a result,can rotate exactly at the supply frequency or a sub-multiple of the supply frequency.
The magnetic field on the rotor is either generated by current delivered through slip rings or by a
permanent magnet. Other types of motors include eddy current motors, and also AC/DC mechanically
commutated machines in which speed is dependent on voltage and winding connection.
2.3 MOTOR SELECTION:
This table will compare the advantages and disadvantages of each type of motor.The Table summarizes the comparison between BLDC motor and other types of motor.
Table 2.1: Advantages and Disadvantages of different types of motor
Type Advantages Disadvantages Typical Application Typical Drive
Comparing brushed DC motors and induction motors to BLDC motors, BLDC motors havemany advantages over disadvantages. Brushless DC motors require less maintenance andtherefore have a longer life span as compared to brushed DC motors. BLDC motors producemore output power per frame size than brushed DC motors and induction motors. Because therotor is made of permanent magnets, the rotor inertia is less, comparing with other types of
motors. This low rotor inertia improves acceleration and deceleration characteristics,shortening operating cycles. Their linear speed/torque characteristics produce predictable speedregulation. With brushless motors, brush inspection is eliminated, making them ideal for areaswith limited access and applications where servicing is difficult. BLDC motors operate muchmore quietly than brushed DC motors, reducing Electromagnetic interference (EMI). Low-voltage models are ideal for battery operation, portable equipment or medical applications. Italso reduces the risk of electric shock.
Based on the above findings, although a BLDC motor is more expensive and harder to control,
its overall advantage proves to be worthy of implementation. Therefore a BLDC motor is
A Hall Effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall
Effect sensors are used for proximity switching, positioning, speed detection, and current sensingapplications.
In its simplest form, the sensor operates as an analogue transducer, directly returning a voltage. With a
known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the
relative position of the magnet can be deduced.
Figure 3.1: Hall sensor
Electricity carried through a conductor will produce a magnetic field that varies with current, and a Hallsensor can be used to measure the current without interrupting the circuit. Typically, the sensor is
integrated with a wound core or permanent magnet that surrounds the conductor to be measured.
Frequently, a Hall sensor is combined with circuitry that allows the device to act in a digital (on/off)
mode, and may be called a switch in this configuration. Commonly seen in industrial applications such a
the pictured pneumatic cylinder, they are also used in consumer equipment; for example some computer
printers use them to detect missing paper and open covers. When high reliability is required, they are
used in keyboards.
Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustionengine ignition timing, tachometers and anti-lock braking systems. They are used in brushless DCelectric motors to detect the position of the permanent magnet. In the pictured wheel with two equallyspaced magnets, the voltage from the sensor will peak twice for each revolution. This arrangement iscommonly used to regulate the speed of disc drives
3.1 HALL EFFECT:
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor,
transverse to an electric current in the conductor and a magnetic field perpendicular to the current. It was
discovered by Edwin Hall in 1879.
The Hall coefficient is defined as the ratio of the induced electric field to the product of the current
density and the applied magnetic field. It is a characteristic of the material from which the conductor is
made, since its value depends on the type, number, and properties of the charge carriers that constitute
From the figure 3.2 notice that sensor are three-wire sensor. This means that two wires, the + V, and the
ground provide dc voltage for the power supply portion of the sensor.
Terminal 0 and ground are used as the output terminals for the sensor. Since this is a three-wire sensor,
the ground terminal is part of the power supply and part of the output circuit. The power supply uses a
voltage regulator to provide the initial current for the Hall-effect element and voltage for the op amp. Th
small sensor terminals are connected to the op amp input terminals.
When a magnetic field is sensed, a small voltage is sent to the op amp and the output of the op amp is
sent to a Schmitt trigger and then to the base of an NPN transistor. When the base of the transistor is
biased, it will go into saturation and current will flow through its emitter-collector circuit to provide a
digital (on/off) output signal. In the current-sinking circuit, notice that the transistor provides a path to
ground when the transistor is biased to saturation.
3.3 HALL EFFECT SENSOR INTERFACE:
Hall effect sensor may require analog circuitry to be interfaced to microprocessors. These interfaces may
include input diagnostics, fault protection for transient conditions, and short/open circuit detection. It
may also provide and monitor the current to the Hall Effect sensor itself. There are precision IC products
available to handle these features.
3.4 HALL PROBE:
A Hall probe contains an indium compound semiconductor crystal such as indium antimonite, mountedon an aluminum backing plate, and encapsulated in the probe head. The plane of the crystal is
perpendicular to the probe handle. Connecting leads from the crystal are brought down through the
handle to the circuit box.
When the Hall Probe is held so that the magnetic field lines are passing at right angles through the sensor
of the probe, the meter gives a reading of the value of magnetic flux density (B). A current is passed
through the crystal which, when placed in a magnetic field has a ―Hall effect‖ voltage developed across
it. The Hall Effect is seen when a conductor is passed through a uniform magnetic field. The natural
electron drift of the charge carriers causes the magnetic field to apply a Lorentz force (the force exertedon a charged particle in an electromagnetic field) to these charge carriers. The result is what is seen as a
charge separation, with a buildup of either positive or negative charges on the bottom or on the top of the
plate. The crystal measures 5 mm square. The probe handle, being made of a non-ferrous material, has n
disturbing effect on the field.
A Hall Probe is enough to measure the Earth's magnetic field. It must be held so that the Earth's field
lines are passing directly through it. It is then rotated quickly so the field lines pass through the sensor in
the opposite direction. The change in the flux density reading is double the Earth's magnetic flux density
A hall probe must first be calibrated against a known value of magnetic field strength. For a solenoid thehall probe is placed in the center .
The Intel MCS-51(Commonly referred to as 8051) is Harvard architecture, single chip microcontroller
Series which was developed by Intel in 1980 for use in embedded systems. Intel‘s original popular in the1980s and early 1990s.While Intel no longer manufactures the MCS-51, binary compatible derivativesRemain popular today. In addition to these physical devices, several companies also offer MCS -51derivatives as IP cores for use in FPGAs or ASICs designs.
Figure 4.1 8051 Microcontroller
Intel's original MCS-51 family was developed using NMOS technology, but later versions, identified ba letter C in their name (e.g., 80C51) used CMOS technology and consumed less power than thei
NMOS predecessors. This made them more suitable for battery-powered devices.
4.1 HISTORY:
The first single-chip microprocessor was the 4-bit Intel 4004 released in 1971, with the Intel 8008 andother more capable microprocessors becoming available over the next several years. However, both
processors required external chips to implement a working system, raising total system cost, and makingit impossible to economically computerize appliances.
The Smithsonian Institution says TI engineers Gary Boone and Michael Cochran succeeded in creating
the first microcontroller in 1971. The result of their work was the TMS 1000, which went commercial in
1974. It combined read-only memory, read/write memory, processor and clock on one chip and was
targeted at embedded systems.
Partly in response to the existence of the single-chip TMS 1000, Intel developed a computer system on a
chip optimized for control applications, the Intel 8048, with commercial parts first shipping in 1977. It
combined RAM and ROM on the same chip. This chip would find its way into over one billion PC
keyboards, and other numerous applications. At that time Intel's President, Luke J. Valenter, stated that
the microcontroller was one of the most successful in the company's history, and expanded the division's
budget over 25%.
Most microcontrollers at this time had two variants. One had an erasable EPROM program memory,
which was significantly more expensive than the PROM variant which was only programmable once.Erasing the EPROM required exposure to ultraviolet light through a transparent quartz lid. One-time
One particularly useful feature of the 8051 core was the inclusion of a Boolean processing engine
Which allows bit-level Boolean logic operations to be carried out directly and efficiently on select
internal registers and select RAM locations. This advantageous feature helped cement the 8051's
popularity in industrial control applications because it reduced code size by as much as 30%. Anot
her valued feature is the including of four bank selectable working register sets which greatly reduce
the amount of time required to complete an interrupt service routine. With a single instruction 8051
can switch register banks as opposed to the time consuming task of transferring the critical registers
to the stack or designated RAM locations. These registers also allowed the 8051 to quickly perform
a context switch which is essential for time sensitive real-time applications
.
The MCS-51 UARTs make it simple to use the chip as a serial communications interface. External pins
can be configured to connect to internal shift registers in a variety of ways, and the internal timers can
also be used, allowing serial communications in a number of modes, both synchronous and
asynchronous. Some modes allow communications with no external components. A mode compatible
with an RS-485 multi-point communications environment is achievable, but the 8051's real strength is
fitting in with existing ad-hoc protocols (e.g., when controlling serial-controlled devices).
Once a UART, and a timer if necessary, have been configured, the programmer needs only to write a
simple interrupt routine to refill the send shift register whenever the last bit is shifted out by the UART
and/or empty the full receive shift register (copy the data somewhere else). The main program then
performs serial reads and writes simply by reading and writing 8-bit data to stacks.
MCS-51 based microcontrollers typically include one or two UARTs, two or three timers, 128 or 256
bytes of internal data RAM (16 bytes of which are bit-addressable), up to 128 bytes of I/O, 512 bytes to64 kB of internal program memory, and sometimes a quantity of extended data RAM (ERAM) located in
the external data space. The original 8051 core ran at 12 clock cycles per machine cycle, with most
instructions executing in one or two machine cycles. With a 12 MHz clock frequency, the 8051 could
thus execute 1 million one-cycle instructions per second or 500,000 two-cycle instructions per second.
Enhanced 8051 cores are now commonly used which run at six, four, two, or even one clock per machine
cycle, and have clock frequencies of up to 100 MHz, and are thus capable of an even greater number of
instructions per second. All SILabs, some Dallas and a few Atmel devices have single cycle cores.
Because the 8051 is an accumulator-based architecture, all arithmetic operations must use the
accumulator, e.g. ADD A, 020h will add the value in memory location 0x20 in the internal RAM to the
accumulator.
One does not need to master these instructions to program the 8051. With the availability of good quality
C compilers, including open source SDCC, virtually all programs can be written with high-level
language.
4.6 RELATED PROCESSORS:
The 8051's predecessor, the 8048, was used in the keyboard of the first IBM PC, where it converted
keypresses into the serial data stream which is sent to the main unit of the computer. The 8048 andderivatives are still used today for basic model keyboards.
The 8031 was a cut down version of the original Intel 8051 that did not contain any internal program
memory (ROM). To use this chip, external ROM had to be added containing the program that the 8031
would fetch and execute. An 8051 chip could be sold as a ROM-less 8031, as the 8051's internal ROM is
disabled by the normal state of the EA pin in an 8031-based design. A vendor might sell an 8051 as an
8031 for any number of reasons, such as faulty code in the 8051's ROM, or simply an oversupply of
8051's and undersupply of 8031's.
Figure 4.3 :Intel 8031 processors
The 8052 was an enhanced version of the original 8051 that featured 256 bytes of internal RAM instead
of 128 bytes, 8 KB of ROM instead of 4 KB, and a third 16-bit timer. The 8032 had these same features
except for the internal ROM program memory. The 8052 and 8032 are largely considered to be obsolete
because these features and more are included in nearly all modern 8051 based microcontrollers.
(formerly Winbond), ST Microelectronics, Silicon Laboratories (formerly Cygnal), Texas
Instruments, Ramtron International, Silicon Storage Technology, Cypress Semiconductor and Analog
Devices.
The 80C537 and 80C517 are CMOS versions, designed for the automotive industry. Enhancements
mostly new peripheral features and expanded arithmetic instructions. The 80C517 has fail save
mechanisms, analog signal processing facilities and timer capabilities and 8 KB on-chip program
memory. Other features include:
256 byte on-chip RAM
256 directly addressable bits
External program and data memory expandable up to 64 KB
8-bit A/D converter with 12 multiplexed inputs
Arithmetic unit can make division, multiplication, shift and normalize operations
Eight data pointers instead of one for indirect addressing of program and external data memory
Extended watchdog facilities
Nine ports
Two full-duplex serial interfaces with own baud rate generators
Four priority level interrupt systems, 14 interrupt vectors
Three power saving modes
4.7 USE AS INTELLECTUAL PROPERTY:
Today, 8051s are still available as discrete parts, but they are mostly used as silicon intellectual
property cores. Available in high-level language source code (VHDL or Verilog) or FPGA netlist forms,
these cores are typically integrated within embedded systems, in products ranging from USB flashdrives to washing machines to complex wireless communication systems on a chip. Designers use 8051
silicon IP cores, because of the smaller size, and lower power, compared to 32 bit processors like ARM
M series, MIPS and BA22. Modern 8051 cores are faster than earlier packaged versions. Design
improvements have increased 8051 performance while retaining compatibility with the original MCS 51
instruction set. The original Intel 8051 ran at 12 clock cycles per machine cycle, and most instructions
executed in one or two machine cycles. A typical maximum clock frequency of 12 MHz meant these old
8051s could execute one million single-cycle instructions, or 500,000 two-cycle instructions, per second
In contrast, enhanced 8051 silicon IP cores now run at one clock cycle per machine cycle, and have clock
frequencies of up to 450 MHz. That means an 8051-compatible processor can now execute 450 million
The main objective of inverters is to produce an ac output waveform from a dc power supply. These are
the types of waveforms required in adjustable speed drives (ASDs), uninterruptible power supplies
(UPS), static var compensators, active filters, flexible ac transmission systems , and voltage
compensators, which are only a few applications. For sinusoidal ac outputs, the magnitude,
frequency, and phase should be controllable. According to the type of ac output waveform, these
topologies can be considered as voltage source inverters (VSIs), where the independently controlled ac
output is a voltage waveform. These structures are the most widely used because they naturally behave a
voltage sources as required by many industrial applications, such as adjustable speed drives (ASDs),
which are the most popular application of inverters; see Fig.5.1
Figure 5.1 Basic inverter circuit
Similarly, these topologies can be found as current source inverters (CSIs), where the independently
controlled ac output is a current waveform. These structures are still widely used in medium-voltage
industrial applications,
where high-quality voltage waveforms are required. Static power converters, specifically inverters, are
constructed from power switches and the ac output waveforms are therefore made up of discrete values.This leads to the generation of waveforms that feature fast transitions rather than smooth ones. For
instance, the ac output voltage produced by the VSI of a standard ASD is a three-levelwaveform (Fig.
14.1c). Although this waveform is not sinusoidal as expected (Fig. 14.1b), its fundamental component
behaves as such. This behavior should be ensured by a modulating technique that controls the amount of
time and the sequence used to switch the power valves on and off. The modulating techniques most used
are the carrier-based technique (e.g., sinusoidal pulse width modulation, SPWM), the space-vector
technique, and the selective-harmonic-elimination (SHE) technique. The discrete shape of the ac output
waveforms generated by these topologies imposes basic restrictions on the applications of inverters. TheVSI generates an ac output voltage waveform composed of discrete values (highd v =dt ); therefore, the
load should be inductive at the harmonic frequencies in order to produce a smooth current waveform. A
capacitive load in the VSIs will generate large current spikes. If this is the case, an inductive filter
between the VSI ac side and the load should be used. On the other hand, the CSI generates an ac output
current waveform composed of discrete values (highdi = dt ); therefore, the load should be capacitive at
the harmonic frequencies in order to produce a smooth voltage waveform.An inductive load in CSIs will
generate large voltage spikes. If this is the case, a capacitive filter between the CSI ac side and
the load should be used. A three-level voltage waveform is not recommended for
medium voltage ASDs due to the high d v =dt that would apply to the motor terminals. Several negative
side effects of this approach have been reported (bearing and isolation problems). As alternatives to
improve the ac output waveforms in VSIs are the multistage topologies (multilevel and multicell). The
basic principle is to construct the required ac output waveform from various voltage levels, which
achieves medium-voltage waveforms at reduced d v = dt . Although these topologies are well developedin ASDs, they are also suitable for static var compensators, active filters, and voltage compensators.
Specialized modulating techniques have been developed to switch the higher number of power valves
involved in these topologies. Among others, the carrier-based (SPWM) and SV-based techniques have
been naturally extended to these applications. In many applications, it is required to take energy from the
ac side of the inverter and send it back into the dc side. For instance, whenever ASDs need to either
brake or slow down the motor speed, the kinetic energy is sent into the voltage dc link (Fig. 14.1a). This
is known as the regenerative mode operation and, in contrast to the motoring mode, the dc link current
direction is reversed due to the fact that the dc link voltage is fixed. If a capacitor is used to maintain thedc link voltage (as in standard ASDs) the energy must either be dissipated or fed back into the
distribution system, otherwise, the dc link voltage gradually increases. The first approach requires the dc
link capacitor be connected in parallel with a resistor, which must be properly switched only when the
energy flows from the motor load into the dc link. A better alternative is to feed back such energy into
the distribution system. However, this alternative requires a reversible-current topology connected
between the distribution system and the dc link capacitor. A modern approach to such a requirement is
to use the active front-end rectifier technologies, where the regeneration mode is a natural operating
mode of the system.
5.2 THREE PHASE INVERTERS:
Single-phase VSIs cover low-range power applications and three-phase VSIs cover the medium- to high-
power applications. The main purpose of these topologies is to provide a three-phase voltage source,
where the amplitude, phase, and frequency of the voltages should always be controllable. Although most
of the applications require sinusoidal voltage waveforms (e.g., ASDs, UPSs, var compensators), arbitrary
voltages are also required in some emerging applications (e g active filters voltage compensators)
The standard three-phase VSI topology is shown in Fig.14.13 and the eight valid switch states are given
in Table 14.3.
Figure 5.2:Three Phase VSI Topology
As in single-phase VSIs, the switches of any leg of the inverter ( S1and S4, S3 and S6,or S5 and S2)
cannot be switched on simultaneously because this would result in a short circuit across the dc link
voltage supply. Similarly, in order to avoid undefined states in the VSI, and thus undefined ac output line
voltages, the switches of any leg of the inverter cannot be switched off simultaneously as this will result
in voltages that will depend upon the respective line current polarity. Of the eight valid states, two of
them (7 and 8 in Table 5.1) produce zero ac line voltages. In this case, the ac line currents freewheel
through either the upper or lower components. The remaining states (1 to 6 in Table 5.1) produce
nonzero ac output voltages. In order to generate a given voltage wave-form, the inverter moves from onestate to another. Thus the resulting ac output line voltages consist of discrete values of voltages that are v
i, 0, and ÿ v i. The selection of the states in order to generate the given waveform is done by the
modulating technique that should ensure the use of only the valid states.
Table 5.1 Valid Switch states for a three phase VSI
Figure5.3: Waveforms of Three Phase Inverter with 120 degrees of operation
5.3POWER MOSFETS:
In three phase or single inverters Thyristor or Mosfet or IGBT‘s are used in general ,but due to
commutation circuit present in Thyristors are not used in inverters . So Mosfets are used because of nocommutation circuit is present so power Mosfets are used for high frequency switching applications likeinverters and choppers.
Unlike the bipolar junction transistor (BJT), the MOSFET device belongs to the unipolar device family because it uses only the majority carriers in conduction . The development of metal- oxidesemiconductor (MOS) technology for microelectronic circuits opened the way for development of th
power metal oxide semiconductor field effect transistor (MOSFET) device in 1975. Selecting the mosappropriate device for a given application is not an easy task because it requires knowledge about thdevice characteristics, their unique features, innovation, and engineering design experience. Unlike low
power (signal devices), high-power devices are more complicated in structure, driver design, and theioperational i -v characteristics are difficult to understand. This knowledge is very important for poweelectronics engineers when designing circuits that will make these devices close to ideal. The devicsymbol for a p - and n-channel enhancement and depletion types are shown in Fig. 5.1. Figure 5.2 showthe i -v characteristics for the n -channel enhancement-type MOSFET. It is the fastest power switchingdevice, with switching frequency >MHz, and with voltage power ratings up to 600 V and current ratingas high as 40 A. Regions of operations for MOSFET will be studied.
Unlike the lateral channel MOSET devices used in much of the IC technology in which the gate, sourceand drain terminals are located at the same surface of the silicon wafer, power MOSFETs use verticachannel structure in order to increase the device power rating . In the vertical channel structure,
the source and drain are on opposite side of the silicon wafer. Figure 6.7a shows a vertical cross-sectionaview for a power MOSFET. Figure 6.7b shows a more simplified representation. There are severadiscrete types of the vertical structure power MOSFET available commercially today, including VMOSFET,U-MOSFET, D-MOSFET, and S-MOSFET [1, 2]. The p – n junction between the p -base (alsreferred to as body or bulk region) and the n -drift region provide the forward voltage blockingcapabilities. The source metal contact is connected directly to the p -base region through a break inthe n-source region in order to allow for a fixed potential to the p -base region during normal devicoperation. When the gate and source terminal are set to the same potential( VGSˆ 0), no channel i
established in the p -base region, that is, the channel region remains un modulated. The lowerdoping in the n -drift region is needed in order to achieve higher drain voltage blocking capabilities. Fothe drain-source current I D to flow, a conductive path must be established between the n- and n
ÿ-regions through the p -base diffusion region.
5.3.2 ON-STATE RESISTANCE:When the MOSFET is in the on-state (triode region), the channel of the device behaves like a constanresistance R DS… on† that is linearly proportional to the change between v DS and i D as given by the
following relation:
The total conduction (on-state) power loss for a given MOSFET with forward current I
Figure 5.6: vertical cross sectional view of Power Mosfet
The value of R DS… on†can be significant and varies between tens of milliohms and a few ohms fo
low-voltage and high-voltage MOSFETS, respectively. The on-state resistance is an important data shee parameter, because it determines the forward voltage drop across the device and its total power lossesUnlike the current-controlled bipolar device, which requires base current to allow the current to flow inthe collector, the power MOSFET device is a voltage-controlled unipolar device and requires only small amount of input (gate) current. As a result, it requires less drive power than the BJT. However, it ia nonlatching current like the BJT, that is, a gate source voltage must be maintained. Moreover, as onlymajority carriers contribute to the current flow, MOSFETs surpass all other devices in switching speedwhich switching speeds can exceed a few megahertz. Comparing the BJT and the MOSFET, the BJT hagreater power handling capabilities and smaller switching speed, while the MOSFET device has les
power handling capabilities and relatively fast switching speed. The MOSFET device has a higher onstate resistor than the bipolar transistor. Another difference is that the BJT parameters are more sensitiveto junction temperature when compared to the MOSFET and, unlike the BJT,MOSFET devices do nosuffer from second breakdown voltages and sharing current in parallel devices is possible
5.3.3 MOSFET OPERATION:
Most MOSFET devices used in power electronics applications are of the n -channel, enhancement typelike that shown in Fig. 6.6a. For the MOSFET to carry drain current, a channel between the drain and thesource must be created. This occurs when the gate-to-source voltage exceeds the device threshold voltagV Th. For v GS > V Th , the device can be either in thetriode region, which is also called ‗‗constan
resistance‘‘ region, or in the saturation region, depending on the value of v DS .Forgiven v GS , wi tsmall v DS( v DS< v GSÿ V Th), the device operates in the triode region (saturation region in the BJT)and forlarger v DS… vDS> v GSÿ V Th), the device enters the saturation region (active region in th
BJT). For v GS < V Th, the device turns off, with drain current almost equal to zero. Under both region
of operation, the gate current is almost zero. This is why the MOSFET is known as a voltage-drivendevice and, therefore, requires simple gate control circuit.The characteristic curves in Fig. 6.6b show tha
there are three distinct regions of operation labeled as triode region, saturation region, and cut-off regionWhen used as a switching device, only triode and cut-off regions are used, whereas, when it is used as anamplifier, the MOSFET must operate in the saturation region, which corresponds to the active region inthe BJT. The device operates in the cut-off region (off-state) when V GS< v Th, resulting in no inducedchannel. In order to operate the MOSFET in either the triode or saturation region, a channel must first b
induced. This can be accomplished by applying gate-to-source voltage that exceeds v Th, that is,.
5.4MOSFET DRIVER:
To turn a power MOSFET on, the gate terminal must be set to a voltage at least 10 volts greater than thesource terminal (about 4 volts for logic level MOSFETs). This is comfortably above the V gs(th) parameter
One feature of power MOSFETs is that they have a large stray capacitance between the gate and thother terminals, Ciss. The effect of this is that when the pulse to the gate terminal arrives, it must firscharge this capacitance up before the gate voltage can reach the 10 volts required. The gate terminal theneffectively does take current. Therefore the circuit that drives the gate terminal should be capable osupplying a reasonable current so the stray capacitance can be charged up as quickly as possible. Th
best way to do this is to use a dedicated MOSFET driver chip.
Some require the MOSFET source terminal to be grounded (for the lower 2 MOSFETs in a full bridge o just a simple switching circuit). Some can drive a MOSFET with the source at a higher voltage. Theshave an on-chip charge pump, which means they can generate the 22 volts required to turn the upperMOSFET in a full bridge on.
Often you will see a low value resistor between the MOSFET driver and the MOSFET gate terminalThis is to dampen down any ringing oscillations caused by the lead inductance and gate capacitancwhich can otherwise exceed the maximum voltage allowed on the gate terminal. It also slows down thrate at which the MOSFET turns on and off. This can be useful if the intrinsic diodes in the MOSFET donot turn on fast enough
Interrupts, I/O Ports, A/D Converter, D/A Converter, and PWM Modules) of 8051 deviceSimulation helps to understand hardware configurations and avoids time wasted on setu
PROTEUS Software is used for simulating the microcontroller circuit .In this project supply to the stator
winding depending up on rotor position. The rotor position is sensed by Hall sensors. The hall senso
output is given as input to microcontroller. For simulation purpose the hall sensors are replaced by
switches. In BLDC motors three phase inverter with six step pulses are used for stator supply. The gat
pulses are taken from micocontroller. Depending upon the output of the hall sensor we generate six
pulses from microcontroller which are observed by placing LEDs as shown in above figure
6.4.4ADVANTAGES OF PROTEUS:
The Proteus Design Suite is wholly unique in offering the ability to co-simulate both high and low-level
micro-controller code in the context of a mixed-mode SPICE circuit simulation. With this Virtual System
Modeling facility, you can transform your product design cycle, reaping huge rewards in terms of
reduced time to market and lower costs of development.
If one person designs both the hardware and the software then that person benefits as the hardware
design may be changed just as easily as the software design. In larger organizations where the two roles
are separated, the software designers can begin work as soon as the schematic is completed; there is no
need for them to wait until a physical prototype exists.
In short, Proteus improves efficiency, quality and flexibility throughout the design process.
6.5 PSIM:
PSIM is a simulation software specifically designed for power electronics and motor control. With fastsimulation and friendly user interface, PSIM provides a powerful simulation environment to address yousimulation needs.
PSIM provides an intuitive and easy-to-use graphic user interface for schematic editing. A circuit can beeasily created and edited. Extensive on-line help is available for each component. To handle largesystems, PSIM provides the sub circuit function which allows part of a circuit to be represented by a subcircuit block .
PSIM simulator is the engine of the simulation environment. It uses efficient algorithms to overcome theconvergence problem and long simulation time existing in many other simulation software. The fastsimulation allows repetitive simulation runs and significantly shortens the design cycle.
Simulation results are displayed and evaluated in Simview. Various waveform processing functions, suchas multiple screens and line styles, are provided. Post-processing functions such as addition/subtractionand average/rms value calculation are also provided.
6.6.1 EASY TO USE: PSIM is so easy to use that one hardly needs the User Manual to use the software. Even without prior
experience with CAD software, one could start building a circuit and obtaining results in minutes.
6.6.2 Fast Simulation:PSIM is one of the fastest simulators for power electronics simulation. It achieves fastsimulation while retaining excellent simulation accuracy. This makes it particularly efficient insimulating converter systems of any size, and performing multiple-cycle simulation.
6.6.3 Flexible Control Representation:
PSIM can simulate control circuit in various forms: in analog circuit, s-domain transfer function bloc
diagram, z-domain transfer function block diagram, custom C code, or in Matlab/Simulink. PSIM'control library provides a comprehensive list of components and function blocks, and makes it possible
to build virtually any control scheme quickly and conveniently.
6.6.4 COSIMULATION WITH MATLAB/SIMULINK:
PSIM can perform co-simulation with Matlab/Simulink. This feature (available with the Sim Couple
Module) allows users to make full use of PSIM and Matlab/Simulink in a complementary way.
6.6.5 FREQUENCY RESPONSE ANALYSIS:
While almost all the simulation software require that a switchmode circuit be represented by an average
model first before performing ac analysis, PSIM can perform ac analysis even if the circuit is in switch
mode. This feature greatly reduces the time required to obtain frequency response.
7.1 CIRCUIT SPECIFICATIONThis section covers a BLDC motor drive controlled by microcontroller with the following specifications
Input : 24 volts to 3 phase inverter Power supplies: 5V to microcontroller and Hall sensors
5V and 15 V to MOSFET Driver
Output :
Microcontroller:AT89C51
Hall Sensors :281
Protection : None
7.2 CIRCUIT DESCRIPTION
7.2.1 Starting Power Supply
A power supply is a device that supplies electrical energy to one or more electric loads.
Every power supply must obtain the energy it supplies to its load, as well as any energy itconsumes while performing that task, from an energy source depending on its design.
The power supply circuit will required to provide +5Vdc, +15Vdc and +24Vdc to the whole
system. The table below explains the voltage supply needed for each component.
Components Voltage Required FunctionMicrocontroller +5V Used to power up the
device
Hall Sensors +5V +15V DC is used for the
control the power supply
Motor Drive +15V and +24V Used to power up the
device
Table 7.1: Power Supply
7.2.2WORKING OF HALL SENSORS:Hall Sensors senses the magnetic field means when North pole of a magnet is nearer to the sensor itgives output is high and when south pole of a magnet is nearer to the sensor it gives output is lowWe connect resistor between input and output terminal as shown in figure and output is shown with thehelp of LED and output value is measured with the help of multimeter
In BLDC motor , supply given to the stator depend upon the rotor position and rotor position is sensed by the hall sensor and the output of the hall sensor output is given as input to the microcontroller.We use three hall sensors and the outputs of the three hall sensors are given as input to microcontroller
7.2.3 MICROCONTOLLER CIRCUIT:With the help of microcontroller we generate six waveforms for the three phase inverter circuit in 120degrees of mode of operation (output is six stepped waveform). Depends upon the rotor positionmicrocontroller gives two pulses only means when one pulse is going to be OFF, at the same time
another pulse is ON.7.2.4 BLDC MOTOR DEMONSTRATION:We demonstrate the BLDC motor by the following procedure. We can take two circular plate and are
fixed on a stand .we can place permanent magnets on one circular plate and hall sensors on the anotherPlate. In BLDC motor hall sensors are placed in stator and permanent magnets are placed in rotor. In thesame way we can place a hall sensor on circular plate which can be stationary and permanent magnetsare placed in another circular place which can be rotating part and shown in the figure. Hall sensors are
placed electrically 120 degrees apart means mechanically 60 degrees apart. Magnets are placed 90degrees apart. When rotating circular plate is rotated by hand manually and hall sensors outputs are givento the microcontroller. Depending upon the position of hall sensors we generate the pulses from themicrocontroller.
Figure 7.1 BLDC demonstration
7.2.5 MOSFET DRIVER AND INVERTER:The output pulses from the microcontroller is 5V and it is not sufficient to drive the MOSFET gate so we
need to place the driver circuit for increasing the magnitude and to maintain the constant value in highermagnitude because gate pulse is maintained constant for the full time. when gate pulse is removed mosfeturns off. In 3phase inverter we use 6 mosfets and 3 mosfet drivers are used. One mosfet driver IR2110
gives 2 pulses for mosfets so we use three mosfet drivers. The circuit diagram of mosfet driver andinverter shown in figure. The output of the inverter is a six stepped waveform. In BLDC motor thesupply to the stator is the six stepped waveform ( not sinusoidal ).The wave forms can be observed byconnecting three resistors in star and observed the phase voltages with respect to common point of starconnected resistors.
7.2.6 Total Circuit Now joining all the circuits described above form the total circuit of BLDC motor drive controlled bymicrocontroller is shown as below.
By this project, we have shown the working of BLDC motor which is controlled by microcontroller.By rotating the circular plate with permanent magnets and obtain the output from the hall sensors and
inverter with six stepped waveforms. BLDC motors possess high efficiency. In BLDC motor PM are onthe rotor & electromagnets are on the stator controlled by software
8.1 FUTURE SCOPE:Brushless motor technology makes it possible to achieve specifications. Such motors combine higreliability with high efficiency, and for a lower cost in comparison with brush motor. In futureapplications of DC motors in appliances like hard disks, wheel chairs and toys are replaced by BLDCmotors due to their low maintenance cost and high efficiency
1. Dr. P.S.Bimbhra, Power Electronics, Khanna publications.2. Muhammad H.Rashid, Power Electronics: Circuits, Devices and applications3. Gopal.K.Dubey Fundamentals of Electrical Drives4. Wikepedia.org, Brushless DC electric motor ,
MH 281 is an unipolar Hall effect sensor IC. It incorporates advanced chopperstabilization technology to provide accurate and stable magnetic switch points. The design,specifications and performance have been optimized for applications of solid state switches.
The output transistor will be switched on (BOP) in the presence of a sufficiently strong South pole magnetic field facing the marked side of the package. Similarly, the output will be switchedoff (BRP) in the presence of a weaker South field and remain off with ―0‖ field.
The package type is in a Green version was verified by third party organization. Green package is available by customer ‘s option.
Features and Benefits
CMOS Hall IC Technology Solid-State Reliability Chopper stabilized amplifier stage Unipolar, output switches with absolute value of South pole from magnet Operation down to 3.0V High Sensitivity for direct reed switch replacement applications 100% tested at 125℃ for K Spec. Custom sensitivity / Temperature selection are available.
Applications
Solid state switch Limit switch Current limit Interrupter Current sensing Magnet proximity sensor for reed switch replacement
Package Power Dissipation The power dissipation of the Package is a function of the pad size. This can vary from the
minimum pad size for soldering to a pad size given for maximum power dissipation. Power
dissipation for a surface mount device is determined by TJ(max), the maximum rated junction
temperature of the die, R θJA, the thermal resistance from the device junction to ambient, and the
operating temperature, Ta. Using the values provided on the data sheet for the Package, PD can
be calculated as follows:
T - Ta P
J(max)
D
j a
The values for the equation are found in the maximum ratings table on the data sheet.Substituting these values into the equation for an ambient temperature Ta of 25°C, one can
calculate the power dissipation of the device which in this case is 606 milliwatts.
P (UA) 150C - 25C
606mW 206C/ W
The 206°C/W for the UA package assumes the use of the recommended footprint on a glass
epoxy printed circuit board to achieve a power dissipation of 606 milliwatts. There are otheralternatives to achieving higher power dissipation from the Package. Another alternative would
be to use a ceramic substrate or an aluminum core board such as Thermal Clad. Using a board
material such as Thermal Clad, an aluminum core board, the power dissipation can be doubled
The AT89C51 provides the following standard features: 4K
bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt architecture, afull duplex serial port, on-chip oscillator and clock cir-
cuitry. In addition, the AT89C51 is designed with static logic
for operation down to zero frequency and supports twosoftware selectable power saving modes. The Idle Mode
stops the CPU while allowing the RAM, timer/counters,
serial port and interrupt system to continue functioning. ThePower Down Mode saves the RAM contents but freezesthe oscillator disabling all other chip functions until the next
hardware reset.
Pin Description VCC
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bidirectional I/O port. As anoutput port each pin can sink eight TTL inputs. When 1s
are written to port 0 pins, the pins can be used as high-
impedance inputs.
Port 0 may also be configured to be the multiplexed low-order address/data bus during accesses to external pro-
gram and data memory. In this mode P0 has internal pul-lups.
Port 0 also receives the code bytes during Flash program-
ming, and outputs the code bytes during program verifica-
tion. External pullups are required during program verifica-
tion.
Port 1 Port 1 is an 8-bit bidirectional I/O port with internal pullups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high by
the internal pullups and can be used as inputs. As inputs,
Port 1 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pullups.
Port 1 also receives the low-order address bytes duringFlash programming and verification.
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.
When 1s are written to Port 2 pins they are pulled high by
the internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will source
current (IIL) because of the internal pullups.
Port 2 emits the high-order address byte during fetchesfrom external program memory and during accesses to
external data memory that use 16-bit addresses (MOVX @
DPTR). In this application it uses strong internal pullups
when emitting 1s. During accesses to external data mem
ory that use 8-bit addresses (MOVX @ RI), Port 2 emits thecontents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some
control signals during Flash programming and verification.
Port 3
Port 3 is an 8-bit bidirectional I/O port with internal pullups
The Port 3 output buffers can sink/source four TTL inputsWhen 1s are written to Port 3 pins they are pulled high by
the internal pullups and can be used as inputs. As inputsPort 3 pins that are externally being pulled low will sourc
current (IIL) because of the pullups.
Port 3 also serves the functions of various special featuresof the AT89C51 as listed below:
When the AT89C51 is executing code from external pro-gram memory, PSEN is activated twice each machine
cycle, except that two PSEN activations are skipped duringeach access to external data memory.
EA/VPP
External Access Enable. EA must be strapped to GND in
order to enable the device to fetch code from external pro-gram memory locations starting at 0000H up to FFFFH.Note, however, that if lock bit 1 is programmed, EA will be
internally latched on reset.
EA should be strapped to VCC for internal program execu-tions.
This pin also receives the 12-volt programming enable volt-
age (VPP) during Flash programming, for parts that require12-volt VPP.
XTAL1
Input to the inverting oscillator amplifier and input to the
internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
Oscillator Characteristics XTAL1 and XTAL2 are the input and output, respectively,of an inverting amplifier which can be configured for use as
an on-chip oscillator, as shown in Figure 1. Either a quartz
crystal or ceramic resonator may be used. To drive thedevice from an external clock source, XTAL2 should be left
unconnected while XTAL1 is driven as shown in Figure 2.
There are no requirements on the duty cycle of the external
clock signal, since the input to the internal clocking circuitry
is through a divide-by-two flip-flop, but minimum and maxi-mum voltage high and low time specifications must beobserved.
It should be noted that when idle is terminated by a hardware reset, the device normally resumes program execu
tion, from where it left off, up to two machine cycles beforethe internal reset algorithm takes control. On-chip hardwareinhibits access to internal RAM in this event, but access to
the port pins is not inhibited. To eliminate the possibility o
an unexpected write to a port pin when Idle is terminated byreset, the instruction following the one that invokes Idle
should not be one that writes to a port pin or to externamemory.
Figure 1. Oscillator Connections
C2
XTAL2
C1
XTAL1
GND
Note: C1, C2 = 30 pF 10 pF for Crystals 40 pF 10 pF for Ceramic Resonators
Figure 2. External Clock Drive Configuration
Idle Mode In idle mode, the CPU puts itself to sleep while all the on-
chip peripherals remain active. The mode is invoked bysoftware. The content of the on-chip RAM and all the spe-cial functions registers remain unchanged during this
mode. The idle mode can be terminated by any enabled
interrupt or by a hardware reset.
Status of External Pins During Idle and Power Down Modes Mode Program Memory ALE PSEN PORT0 PORT1 PORT2 PORT3
Power Down Mode In the power down mode the oscillator is stopped, and theinstruction that invokes power down is the last instructionexecuted. The on-chip RAM and Special Function Regis-
ters retain their values until the power down mode is termi-
nated. The only exit from power down is a hardware reset.
Reset redefines the SFRs but does not change the on-chipRAM. The reset should not be activated before VCC is
restored to its normal operating level and must be heldactive long enough to allow the oscillator to restart and sta-bilize.
Lock Bit Protection Modes
Program Memory Lock Bits On the chip are three lock bits which can be left unprogrammed (U) or can be programmed (P) to obtain the addtional features listed in the table below:
When lock bit 1 is programmed, the logic level at the EA pinis sampled and latched during reset. If the device is pow
ered up without a reset, the latch initializes to a randomvalue, and holds that value until reset is activated. It is nec
essary that the latched value of EA be in agreement with
the current logic level at that pin in order for the device tofunction properly.
Program Lock Bits Protection Type
LB1 LB2 LB3
1 U U U No program lock features.
2 P U U MOVC instructions executed from external program memory are disabled from fetching code
bytes from internal memory, EA is sampled and latched on reset, and further programming of the
Flash is disabled.
3 P P U Same as mode 2, also verify is disabled.
4 P P P Same as mode 3, also external execution is disabled.
Programming the Flash The AT89C51 is normally shipped with the on-chip Flash
memory array in the erased state (that is, contents = FFH)
and ready to be programmed. The programming interface
accepts either a high-voltage (12-volt) or a low-voltage(VCC) program enable signal. The low voltage program-
ming mode provides a convenient way to program the
AT89C51 inside the user ’s system, while the high-voltageprogramming mode is compatible with conventional thirdparty Flash or EPROM programmers.
The AT89C51 is shipped with either the high-voltage or
low-voltage programming mode enabled. The respectivetop-side marking and device signature codes are listed inthe following table.
VPP = 12V VPP = 5V
Top-Side Mark AT89C51
xxxx yyww AT89C51
xxxx-5
yyww
Signature (030H)=1EH
(031H)=51H
(032H)=FFH
(030H)=1EH
(031H)=51H
(032H)=05H
The AT89C51 code memory array is programmed byte-by-
byte in either programming mode. To program any non-
blank byte in the on-chip Flash Memory, the entire memorymust be erased using the Chip Erase Mode.
Programming Algorithm: Be fore pr ogr amm ing th
AT89C51, the address, data and control signals should bset up according to the Flash programming mode table anFigures 3 and 4. To program the AT89C51, take the follow
ing steps.
1. Input the desired memory location on the addres
lines.
2. Input the appropriate data byte on the data lines.3. Activate the correct combination of control signals.
4. Raise EA/VPP to 12V for the high-voltage programming
mode.
5. Pulse ALE/PROG once to program a byte in the Flasarray or the lock bits. The byte-write cycle is self-timed and
typically takes no more than 1.5 ms. Repeat steps1 through 5, changing the address and data for the
entire array or until the end of the object file is reached.
Data Polling: The AT89C51 features Data Polling to indi-cate the end of a write cycle. During a write cycle, a
attempted read of the last byte written will result in the com
plement of the written datum on PO.7. Once the write cyclehas been completed, true data are valid on all outputs, andthe next cycle may begin. Data Polling may begin any tim
after a write cycle has been initiated.
Ready/Busy: The progress of byte programming can als
be monitored by the RDY/BSY output signal. P3.4 is pulled
low after ALE goes high during programming to indicateBUSY. P3.4 is pulled high again when programming is
Operating Temperature .................................. -55°C to +125°C *NOTICE: Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent dam-
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin
with Respect to Ground .....................................-1.0V to +7.0V
Maximum Operating Voltage............................................. 6.6V
DC Output Current...................................................... 15.0 mA
age to the device. This is a stress rating only and
functional operation of the device at these or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect devicereliability.
DC Characteristics T A = -40°C to 85°C, VCC = 5.0V 20% (unless otherwise noted)
Symbol Parameter Condition Min Max Units
VIL Input Low Voltage (Except EA) -0.5 0.2 VCC - 0.1 V
VIL1 Input Low Voltage (EA) -0.5 0.2 VCC - 0.3 V
VIH Input High Voltage (Except XTAL1, RST) 0.2 VCC + 0.9 VCC + 0.5 V
VIH1 Input High Voltage (XTAL1, RST) 0.7 VCC VCC + 0.5 V VOL Output Low Voltage(1) (Ports 1,2,3) IOL = 1.6 Ma 0.45 V
VOL1 Output Low Voltage(1)
(Port 0, ALE, PSEN) IOL = 3.2 mA 0.45 V
VOH Output High Voltage
(Ports 1,2,3, ALE, PSEN) IOH = -60 A, VCC = 5V 10% 2.4 V
IOH = -25 A 0.75 VCC V
IOH = -10 A 0.9 VCC V
VOH1 Output High Voltage
(Port 0 in External Bus Mode) IOH = -800 A, VCC = 5V 10% 2.4 V
IOH = -300 A 0.75 VCC V
IOH = -80 A 0.9 VCC V
IIL Logical 0 Input Current (Ports 1,2,3) VIN = 0.45V -50 A ITL Logical 1 to 0 Transition Current
(Ports 1,2,3) VIN = 2V, VCC = 5V 10% -650 A
ILI Input Leakage Current (Port 0, EA) 0.45 < VIN < VCC 10 A
RRST Reset Pulldown Resistor 50 300 K
CIO Pin Capacitance Test Freq. = 1 MHz, T A = 25°C 10 pF
ICC Power Supply Current Active Mode, 12 MHz 20 mA
Idle Mode, 12 MHz 5 mA
Power Down Mode(2) VCC = 6V 100 A
VCC = 3V 40 A
Notes: 1. Under steady state (non-transient) conditions, IOL must be externally limited as follows:Maximum IOL per port pin: 10 mA
Maximum IOL per 8-bit port: Port 0: 26 mA Ports 1, 2, 3: 15 mA
Maximum total IOL for all output pins: 71 mA
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test conditions.
AC Characteristics (Under Operating Conditions; Load Capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; Load Capacitance for all otheroutputs = 80 pF)
External Program and Data Memory Characteristics
Symbol Parameter 12 MHz Oscillator 16 to 24 MHz Oscillator Units Min Max Min Max
1/tCLCL Oscillator Frequency 0 24 MHz
tLHLL ALE Pulse Width 127 2tCLCL-40 ns
t AVLL Address Valid to ALE Low 43 tCLCL-13 ns
tLLAX Address Hold After ALE Low 48 tCLCL-20 ns
tLLIV ALE Low to Valid Instruction In 233 4tCLCL-65 ns
tLLPL ALE Low to PSEN Low 43 tCLCL-13 ns
tPLPH PSEN Pulse Width 205 3tCLCL-20 ns
tPLIV PSEN Low to Valid Instruction In 145 3tCLCL-45 ns tPXIX Input Instruction Hold After PSEN 0 0 ns
tPXIZ Input Instruction Float After PSEN 59 tCLCL-10 ns
tPXAV PSEN to Address Valid 75 tCLCL-8 ns
t AVIV Address to Valid Instruction In 312 5tCLCL-55 ns
tPLAZ PSEN Low to Address Float 10 10 ns
tRLRH RD Pulse Width 400 6tCLCL-100 ns
tWLWH WR Pulse Width 400 6tCLCL-100 ns
tRLDV RD Low to Valid Data In 252 5tCLCL-90 ns
tRHDX Data Hold After RD 0 0 ns tRHDZ Data Float After RD 97 2tCLCL-28 ns
tLLDV ALE Low to Valid Data In 517 8tCLCL-150 ns
t AVDV Address to Valid Data In 585 9tCLCL-165 ns
tLLWL ALE Low to RD or WR Low 200 300 3tCLCL-50 3tCLCL+50 ns
t AVWL Address to RD or WR Low 203 4tCLCL-75 ns
tQVWX Data Valid to WR Transition 23 tCLCL-20 ns
tQVWH Data Valid to WR High 433 7tCLCL-120 ns
tWHQX Data Hold After WR 33 tCLCL-20 ns
tRLAZ RD Low to Address Float 0 0 ns tWHLH RD or WR High to ALE High 43 123 tCLCL-20 tCLCL+25 ns
Floating channel designed for bootstrap operation Fully operational to +500V or
+600V Tolerant to negative
transient voltage dV/dt
immune Gate drive supply range from 10 to 20V Undervoltage lockout for both channels 3.3V logic compatible Separate logic supply range from
3.3V to 20V Logic and power ground
±5V of fset CMOS Schmitt-triggered inputs with pull-down Cycle by cycle edge-triggeredshutdown logic Matched propagation delay for bothchannels Outputs in phase with inputs
driver cross-conduction. Propagation delays are matched to simplify use in high
frequency applications. The floating channel can be used to drive an N-channel power MOSFET or IGBT in the high side configuration which operates up to 500 or 600
volts.
Absolute Maximum Ratings
Absolute maximum ratings indicate sustained limits beyond which damage to the
device may occur. All voltage param- eters are absolute voltages referenced to
COM. The thermal resistance and power dissipation ratings are measured under
board mounted and still air conditions. Additional information is shown in Figures28 through 35.
Symbol Definition Min. Max. Units VB High side floating supply voltage (IR2110) -0.3 525
V
(IR2113) -0.3 625 VS High side floating supply offset voltage VB - 25 VB + 0.3
VHO High side floating output voltage VS - 0.3 VB + 0.3 VCC Low side fixed supply voltage -0.3 25
VLO Low side output voltage -0.3 VCC + 0.3 VDD Logic supply voltage -0.3 VSS + 25 VSS
Logic supply offset voltage VCC - 25 VCC + 0.3
VIN Logic input voltage (HIN, LIN & SD) VSS - 0.3 VDD + 0.3 dVs/dt Allowable offset supply voltage transient (figure 2) — 50 V/ns
PD Package power dissipation @ TA +25°C (14 lead DIP) — 1.6 W
R THJA Thermal resistance, junction to ambient (14 lead DIP) — 75 °C/W
(16 lead SOIC) — 100 TJ Junction temperature — 150
°C TS Storage temperature -55 150 TL Lead temperature (soldering, 10 seconds) — 300
Recommended Operating Conditions The input/output logic timing diagram is shown in figure 1. For proper operationthe device should be used within the recommended conditions. The VS and VSSoffset ratings are tested with all supplies biased at 15V dif f erential. Typical ratingsat other bias conditions are shown in figures 36 and 37.
Symbol Definition Min. Max. Units VB High side floating supply absolute voltage VS + 10 VS + 20
V
VS High side floating supply offset voltage (IR2110) Note 1 500
(IR2113) Note 1 600 VHO High side floating output voltage VS VB VCC Low side fixed supply voltage 10 20
VLO Low side output voltage 0 VCC VDD Logic supply voltage VSS + 3 VSS + 20
VSS Logic supply offset voltage -5 (Note 2) 5 VIN Logic input voltage (HIN, LIN & SD) VSS VDD TA Ambient tem erature -40 125 °C
Note 1: Logic operational for VS of -4 to +500V. Logic state held for VS of -4V to-VBS. (Please refer to the Design Ti p DT97-3 for moredetails). Note 2: When VDD < 5V, the minimum VSSoffset is limited to -VDD.
Description VDD Logic supply HIN Logic input for high side gate driver output (HO), in phase SD Logic input for shutdown LIN Logic input for low side gate driver output (LO), in phase VSS Logic ground
VB High side floating supply HO High side gate drive output VS High side floating supply return VCC Low side supply LO Low side gate drive output COM Low side return
N-channel enhancement modestandard level field-effect powertransistor in a plastic envelope using’trench’ technology. The device
features very low on-state resistanceand has integral zener diodes givingESD protection up to 2kV. It isintended for use in switched modepower supplies and general purposeswitching applications.
PINNING - TO220AB PIN CONFIGURATION SYMBOL
PIN DESCRIPTIONd
tab
1 gate
2 drain
3 source tab
drain
g
1 2 3 s
LIMITING VALUES Limiting values in accordance with the Absolute Maximum System (IEC 134)
SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT
VDS
VDGR
VGSID
ID
IDM Ptot
Tstg, T j
Drain-source voltageDrain-gate voltage
Gate-source voltageDrain current (DC)Drain current (DC)Drain current (pulse peak value)Total power dissipationStorage & operating temperature
-RGS = 20 k
-Tmb = 25 ˚CTmb = 100 ˚CTmb = 25 ˚CTmb = 25 ˚C -
--
-----
- 55
5555
204935160110175
V V V A A A
W̊C
ESD LIMITING VALUE
SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT
VC Electrostatic discharge capacitorvoltage, all pins
STATIC CHARACTERISTICS T j= 25˚C unless otherwise specified
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
V(BR)DSS Drain-source breakdown VGS = 0 V; ID = 0.25 mA; 55 - - V voltage T j = -55˚C 50 - -
VGS(TO) Gate threshold voltage VDS = VGS; ID = 1 mA 2.0 3.0 4.0 V T j = 175˚C 1.0 - - V T j = -55˚C - - 4.4 IDSS Zero gate voltage drain current VDS = 55 V; VGS = 0 V; - 0.05 10 A
T j
= 175˚C - - 500 A IGSS Gate source leakage current VGS = 10 V; VDS = 0 V - 0.04 1 A
T j = 175˚C - - 20 A V(BR)GSS Gate source breakdown voltage IG = 1 mA; 16 - - V
RDS(ON) Drain-source on-state VGS = 10 V; ID = 25 A - 15 22 m resistance T j = 175˚C - - 42 m