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Page 1: ID 610C: Introduction to BLDC Motor Control

1

ID 610C: Introduction to BLDC Motor Control

Avnet

Jim Carver

Technical Director, Advanced Architectures

12 October 2010

Version 1.0

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Renesas Technology and Solution Portfolio

Microcontrollers

& Microprocessors#1 Market share

worldwide *

Analog and

Power Devices#1 Market share

in low-voltage

MOSFET**

Solutions

for

Innovation

Solutions

for

InnovationASIC, ASSP

& MemoryAdvanced and

proven technologies

* MCU: 31% revenue

basis from Gartner

"Semiconductor

Applications Worldwide

Annual Market Share:

Database" 25

March 2010

** Power MOSFET: 17.1%

on unit basis from

Marketing Eye 2009

(17.1% on unit basis).

In the session 110C, Renesas Next Generation Microcontroller and Microprocessor Technology Roadmap, Ritesh Tyagi introduces this high level image of where the Renesas Products fit. The big picture.

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Renesas Technology and Solution Portfolio

Microcontrollers

& Microprocessors#1 Market share

worldwide *

Analog and

Power Devices#1 Market share

in low-voltage

MOSFET**

ASIC, ASSP

& MemoryAdvanced and

proven technologies

* MCU: 31% revenue

basis from Gartner

"Semiconductor

Applications Worldwide

Annual Market Share:

Database" 25

March 2010

** Power MOSFET: 17.1%

on unit basis from

Marketing Eye 2009

(17.1% on unit basis).

Solutions

for

Innovation

Solutions

for

Innovation

This is where our session, 610C, is focused within the ‘Big picture of Renesas Products’, Microcontroller and Microprocessors.

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Microcontroller and Microprocessor Line-up

Superscalar, MMU, Multimedia� Up to 1200 DMIPS, 45, 65 & 90nm process

� Video and audio processing on Linux

� Server, Industrial & Automotive

� Up to 500 DMIPS, 150 & 90nm process

� 600uA/MHz, 1.5 uA standby

� Medical, Automotive & Industrial

� Legacy Cores

� Next-generation migration to RX

High Performance CPU, FPU, DSC

Embedded Security

� Up to 10 DMIPS, 130nm process

� 350 uA/MHz, 1uA standby

� Capacitive touch

� Up to 25 DMIPS, 150nm process

� 190 uA/MHz, 0.3uA standby

� Application-specific integration

� Up to 25 DMIPS, 180, 90nm process

� 1mA/MHz, 100uA standby

� Crypto engine, Hardware security

� Up to 165 DMIPS, 90nm process

� 500uA/MHz, 2.5 uA standby

� Ethernet, CAN, USB, Motor Control, TFT Display

High Performance CPU, Low Power

Ultra Low PowerGeneral Purpose

Here are the MCU and MPU Product Lines, I am not going to cover any specific information on these families, but rather I want to show you where this session is focused

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Microcontroller and Microprocessor Line-up

Superscalar, MMU, Multimedia� Up to 1200 DMIPS, 45, 65 & 90nm process

� Video and audio processing on Linux

� Server, Industrial & Automotive

� Up to 500 DMIPS, 150 & 90nm process

� 600uA/MHz, 1.5 uA standby

� Medical, Automotive & Industrial

� Legacy Cores

� Next-generation migration to RX

High Performance CPU, FPU, DSC

Embedded Security

� Up to 10 DMIPS, 130nm process

� 350 uA/MHz, 1uA standby

� Capacitive touch

� Up to 25 DMIPS, 150nm process

� 190 uA/MHz, 0.3uA standby

� Application-specific integration

� Up to 25 DMIPS, 180, 90nm process

� 1mA/MHz, 100uA standby

� Crypto engine, Hardware security

� Up to 165 DMIPS, 90nm process

� 500uA/MHz, 2.5 uA standby

� Ethernet, CAN, USB, Motor Control, TFT Display

High Performance CPU, Low Power

Ultra Low PowerGeneral Purpose

These are the products where this presentation applies

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Agenda

� Motor Types Overview

� BLDC Motor Applications

� Comparison of DC to Brushless DC Motors

� Hall Sensors

� Six-Step Commutation

� Sensorless Commutation with Back-EMF

� Vector Motor Control basics

� Closed-Loop Speed Control

� Introduction to BLDC Motor Control Evaluation Kit

� Summary

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Motor Types

All the popular motor types have their specific applications, and all can be controlled with microcontrollers.

We will talk about Brushless DC motors as it is the fast growing motor type today.

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Expanding BLDC Motor Control Applications

AC, DC

and

Universal

Motors

Transition to

BLDCAs consumers demand

more energy efficient

products, more BLDC

motors are being used.

Motors used in modern Air conditioners, home appliances, tools, even electric bikes are all going to Brushless DC.

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Brushed DC Motors Review

� A winding assembly (armature) within a stationary magnetic field

� Brushes and Commutators switch current to different windings in correct relation to the outer permanent magnet field.

� Pros:

� Electronic control is simple, no need to commutate in controller

� Requires only four power transistors

� Cons:

� A sensor is required for speed control

� The brushes and commutator create sparks and wear out

� Sparks limit peak power

� Heat in armature is difficult to remove

� Low power density

We will find that DC motors have deserved their popularity over the years, but that improvements in motor design and in low-cost microcontrollers makes the BLDC option much more favorable.

We will use the DC motor as a guide, since most people have a good intuitive notion of how a DC motor operates, so that we can better understand the workings of the BLDC motor.

We will see that the cons of the DC motor are well addressed when switching over to BLDC motors, and this justifies the added controller complexity.

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Brushless DC Motors

Permanent

Magnet

Rotor

Stator

windings

� Permanent magnet rotor within stationary windings

Pros:

� No brushes or commutator to wear out

� No sparks and no extra friction

� More efficient than DC motor

� Higher speed than DC motor

� Higher power density than DC motor

Cons:

� Rotor sensor OR sensorless methods needed to commutate

� Requires six power transistors

The Brushless DC motor is a DC motor made inside-out, and without the brushes, obviously.

It provides the advantage of a permanent magnet, which means that all the power applied can be used for torque.

It has the windings near the outside, which means that heat can flow through the outer wall and be easily dissipated. The DC motor cannot do this.

The lack of brushes means that we avoid the friction, sparks, and the “ring fire” a.k.a. “ring of fire” that prevents DC motors from going high speed.

But, the need for six transistors instead of four (or two, or even one for the simplest DC control) means that the electronics cost is going to be higher and the electronic commutation makes it more complicated.

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Brushed DC Commutation

� The windings in the armature are switched to the DC power by the brushes and armature

� Each winding sees a positive voltage, then a disconnect, then a negative voltage

� The field produced in the armature interacts with the stationary magnet, producing torque and rotation

+

-

N S

U

+

-

U

Real DC motors vary a lot, but this one is a good representation.

Even though this model with three windings in the armature does exist, you are more likely to find more commutator bars, more windings, and more brushes in DC motors, especially true the larger they are.

The principle of the windings being switched DC voltage is still the same, but the waveform will get more complicated.

This model is shown as a simple example, and one that best translates into the “inside-out” model of the BLDC motor.

Note the sparks at the brushes, this is where ionization can potentially cause a short circuit from brush to brush – “ring fire”.

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DC Motor Bridge

� The DC motor needs four transistors to operate the DC motor

� The combination of transistor is called an H-Bridge, due to the obvious shape

� Transistors are switched diagonally to allow DC current to flow in the motor in either direction

� The transistors can be Pulse Width Modulated to reduce the average voltage at the motor, useful for controlling current and speed

0

1

1

1

0

0

0

The current flowing into the DC motor can be fully controlled with the H-Bridge. This includes both forward and reverse rotation, at different levels, by using Pulse Width Modulation. Note that the current in the motor does not disappear between pulses, but continues flowing through the diode in the adjacent transistor (flyback), as shown in the dotted line. The inductance in the armature smoothes the current, and keeps it flowing between pulses.

Also, it is possible to slow down the motor by applied a controlled (PWM) short circuit. This will build up current in the motor using the BEMF as the driving force. The PWM can be used here to direct the current back into the bus, causing regeneration.

Motoring and breaking in both directions make up all possible operating modes of a DC motor, also called Four-Quadrant operation. Brushless DC motors also offers this mode of operation.

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Three-Phase Bridge to Drive BLDC Motor

� The Brushless DC motor is really a DC motor constructed inside-out, but without the Brushes and Commutators

� The mechanical switches are replaced with transistors

� The windings are moved from the armature, to the stator

� The magnet is moved from the outside to become the rotor

N S

N S

UVW

Here we see the transition from DC to Brushless DC motors. Especially the replacement of the brushes and commutators with the six transistor (three-phase) bridge.

Of course, all these diagrams are extreme simplifications. In real life, the magnetic fields are carried by iron laminations, which close the magnetic loops and keep the air gaps to a minimum. This is necessary for all motors to be most efficient.

We see the transistors here as MOSFETs, and that is a very popular choice for lower voltages. In higher voltage applications, IGBTs, or Insulated Gate Bipolar Transistors are used. On either case, there must be a diode in parallel with each transistor to handle inductive kick or flyback currents. This is built into most devices nowadays, but in case you want to use bipolar transistors, it may not be there.

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Six-step Commutation

UVW

At any one time, one winding is connected to positive, through an upper transistor, one is Negative (lower transistor) and one is turned off

This is also called Trapezoidal or 120-degree commutation.

Though the 120-degree term is not obvious to most people, it really just means that one winding, or phase, is turned off at any moment, so that only 2/3rds of the windings are active. As we will see, 180-degree commutation uses all three windings at all times.

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Six-Step Current Waveform

� Here we see the individual steps in a real trapezoidal current waveform

� The PWM ripple is visible when the phase is active

� The rising and falling edges are sloped, giving the trapezoidal shape

� The amount of slope is a function of the winding inductance

Here is an oscilloscope shot of a typical six-step phase current.

The “noise” is caused by the PWM leaving some ripple on the current waveform.

The dip in the middle is caused by the current being switched between the other two phases, where this phase sees the transition.

The rise and fall time are sometimes slower, creating a more trapezoidal shape, reflecting the name.

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Hall Sensors

Hall Sensors detect magnetic fields, and

can be used to sense rotor angle

The output is a digital 1 or 0 for each

sensor, depending on the magnetic field

nearby

Each is mounted 120-degrees apart on

the back of the motor

As the rotor turns, the Hall sensors

output logic bits which indicate the angle N

S

H1 H2

H3

The Hall sensor, named after the man who discovered the effect, create very low level changes in voltage in proportion to a local magnetic field. Most sensors on the market include the amplification and comparator needed to make them a digital device.

They add cost and length to the motor, and they are subject the harsh environment of the motor, so they limit the heat capability and power of the motor. The rest of the motor made with copper, iron and magnets can normally handle much more heat than silicon can.

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Hall Sensor Commutation

The combination of all

three sensors produce

six unique logic

combinations or steps

These three bits are

decoded into the motor

phase combinations

You can take the three hall bits and asign them a number, based on their binary states. You could say that step 1 is binary 101, step 2 is 001, etc. Filling in a table of 6 combinations, plus the two other invalid states of 000 and 111 gives all the combinations. Then, let the U-phase upper transistor be ON when the Halls are equal to 001 (decimal 1) or 101 (decimal 5).

Of course, this table is only valid when the motor is going in one direction. For reverse operation, you could build a new table where the opposite transistor (swap upper and lower) is on for each state.

Remember, we describe these as being fully on or off for clarity, but really they are PWM’d at some duty cycle most of the time.

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3-Phase PWM

We can divide up the

phase data into

individual transistor

gate signals

Now we can see how

we can modulate one

transistor at a time to

regulate the motor

voltage, and also the

speed

The transistors can be Pulse Width Modulated one one transistor, with the other diagonal phase just switched fully as, as is shown.

Even though we may not modulate the lower transistor, the voltage seen at the motor is still a function of the PWM, so both positive and negative signals from phase to phase are controlled in proportion to the duty.

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Sensorless Commutation

� Instead of using sensors like Halls, we can let the motor tell us which phase should be energized

� The Brushless DC motor acts as a generator when it rotates, creating voltages

� The three phases produce three voltages 120-degrees apart

� The voltage generated by the motor is called Back Electro-Motive Force, a.k.a. Back-EMF or just BEMF

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Brushless DC Motor BEMF

� The Back-EMF is the voltage generated in stator windings as the rotor moves

� BEMF voltages are more or less sinusoidal (depending on the motor) and are symmetrical from phase to phase

� We detect the zero crossings of each phase to commutate

� The motor MUST be moving to generate BEMF voltages

The rotating vector is shown to simulate the BEMF voltage of a motor spinning at constant speed. The time-domain sinusoids what they would look like on a scope. The amplitude and frequency are both proportional to speed, and the phase relationship is 120 degrees between them for a 3-phase motor.

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Brushless DC Motor BEMF

� The Back-EMF is the voltage generated in stator windings as the rotor moves

� BEMF voltages are more or less sinusoidal (depending on the motor) and are symmetrical from phase to phase

� We detect the zero crossings of each phase to commutate

� The motor MUST be moving to generate BEMF voltages

Here we can look at the waveforms and zero crossings without the animation.

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Startup of BEMF System

� Since only a spinning motor generates BEMF signals

� Start the motor in open loop

� First align rotor to a known angle

� Then energize the windings to step rotor to next step

� Accelerate steps until speed is sufficient to “see”BEMF zero crossings reliably

� Switch to BEMF commutation

� Once operating, this is almost identical to six-step operation with Hall sensors

The alignment phase has already been shown.

As noted, a motor that is not turning cannot generate BEMF signals

So we first have to get it spinning to a point when the BEMF is visible, using open loop methods.

Sending a series of pulses to a motor of unknown angle could produce reverse direction, so we use the alignment stage to set the rotor to a known state first, then begin pulsing it from there, to help guarantee a solid startup in the right direction.

The best amount of current used to align and spin the motor, the time it takes to align, the rate at which we accelerate the motor, and the point at which we switch to BEMF mode are all functions of the motor and load, so they must be determined separately for each system.

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Sinusoidal Methods

� Stepped commutation methods work well, but…

� The Back-EMF waveform is more sinusoidal than trapezoidal

� If we can match the sinusoidal waveform, we can improve performance

� We will show two sinusoidal methods:

� 180-Degree Sinusoidal

� “Field Oriented” or “Vector” control

Even the DC motor windings generate sinusoidal voltages, but the commutators only allow a stepped commutation. By using a modulation method that matches the BEMF voltage in the BLDC motor, we can get the most optimal torque efficiency and smoothness.

Sinusoidal is the default, because it is the most natural to derive from the rotating magnetic field of the rotor. In pure form, sine waves will not have any harmonic content that will cause audible noise and ripple in the torque. Torque ripple can be translated into the mechanical system as vibration or noise.

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180° Sinusoidal Commutation

� Modulates sine waves in all three windings

� Pros:

� No square edges

� Lower Torque Ripple then six-step drive

� Lower audible noise

� Higher efficiency and torque

� Stator angle is rotated smoothly rather than in 60 degree jumps

� Each phase is utilized all of the time

� Cons:

� Needs higher resolution feedback to calculate sine waves with low distortion

� Needs more sophisticated processing to calculate sine PWM values on the fly

� Bandwidth of currents are limited due to motor impedance, this hurts high speed performance

In this method, a sine amplitude is calculated and stored in a table. The amplitude is used to determine PWM value for that phase at that particular angle. The angle, of course, being read from a high resolution sensor like an optical encoder.

The voltage is generated as a sine, and the BEMF voltage is a sine, so the resultant current is the sum of the three phases into a smooth net torque. The problem is as the speed goes up, the generated sine wave may not produce a current that is in phase. The higher speed means higher sine frequency, and the resistive and inductive components in the motor create a passive low-pass filter with inherent phase lag. That results in reduced torque efficiency as the speed goes up, which is not what we want from an optimal system.

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θ

*rω

Speed Regulatorrω∆

*

qi

0*

=dirω

id PI

Regulator

iq PI

Regulator d,qto

βα,

)(1 θ−T

Motor Model

Based Flux and

Position Observer

qi

di

*

qU

*

dU

*

αU

*

βU

Voltage

Source

3-phase

Inverter

SIN

PWM

PWM1~6

to

a, b, c

βα,

3-phase

PMSM

to

d,q

βα,

)(θT

ai

bidi

qi

αiβi

a,b,c

to

βα,

Speed Estimationθ

DC Bus

Vector (Field Oriented Control) Drive

� This method mathematically converts the 3-phase voltage and current into a simple DC motor representation

� Uses this data to calculate the best angle for commutation

� Creates new 3-phase sinusoidal PWM based on calculation

� Repeats the calculations at PWM frequency

� Pros:

� Highest Torque efficiency

� Highest Bandwidth

� Widest Speed Range

� Lowest Audible Noise

� Cons:

� Complicated Algorithm

� Needs powerful processor

There are actually two methods being presented here at DevCon. One method uses an optical encoder signal to tell the processor what the motor angle is at all times. This offers the ability to control the motor at very low speeds.

The other method, called Sensorless Vector, does an added computational step in estimating the motor position based on the last samples taken. This is a great way to reduce cost at the motor, while still giving the advantages of Vector control. But, it also means that operation at very low speeds is not possible, since position estimation cannot derive true position out of the noise. The sensorless method still finds many applications where best performance for minimum cost is desired, and where very low speed is not necessary.

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BLDC Motor Speed Control

� The goal of most Electronic Motor Control Systems is Speed Control

� Speed Control systems are more or less complicated, depending on accuracy required

� The simplest speed control is Open-Loop, that is, without speed feedback

� In this configuration, a speed command is converted to a fixed voltage (PWM duty) which is sent to the motor

� The motor may go the right speed, or it may not, it depends on the load

� Without feedback, there is no way to tell internally what the real speed is and so may require outside adjustment

Speed

Command

Pulse Width

ModulatorTransistors Motor Load

Open loop control can be scaled based on test data, so that at 80% duty, the motor may be at 2000 RPM. It might then be expected that the motor will always run 2000 RPM at 80% duty.

Problem is, if the load changes, the speed changes. If the source voltage (DC Bus) changes, the speed will change. Bearing wear and other environmental factors can affect speed as well.

This can still be OK if you have an outside system, like a human, to intervene and set the duty and speed, or if you just don’t care about regulating the speed within 20 or 30%. So, this still exists as a viable speed control method, despite it’s limitations.

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Closed-Loop Control

� To get automatic speed control, feedback is needed

� Feedback systems could be Hall Sensors, Encoders, Resolvers, tachometers or other devices

� The resolution and bandwidth of the feedback sensor limit the resolution and bandwidth of the speed loop

� Below is a block diagram of a simple control loop

� Our Reference Command is the speed we desire, and the Control Mechanism is our motor and motor control

Control

MechanismSensor

Reference

Command

Feedback

+

-

The block diagram is very generic, representing any kind of closed loop system. It could just as well be the temperature in your refrigerator, the speed of your cruise control, or pressure, etc.

We might also want to control torque or position control in motors, not just speed, but speed is by far the most common type of control. In any case, the concept of loop control still applies, but each reference command and feedback device, as well as the mechanism, has to match the control variable.

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Closed Loop Speed Control

� The generic terms can be replaced with terms common to motor control

� The speed is often referred to as the Greek Letter Omega ω

and motor angle is Theta θ

� The Reference input is shown as Omega star ω *

� The Control Mechanism is a mathematical function, usually a Proportional-Integral (PI) algorithm

� The speed sensors can be the same Hall sensors used for commutation, where the speed is calculated from the time between steps

Hall

Sensors

Speed

Calculation

Motor

PWM

Generation

PI

Controllerω*

ω θ

Mathematically, Theta means angle in Radians, and Omega is speed in Radians per second. Still, some people stick to rotations per minute, RPM, or other units convenient to them.

The whole speed loop is shown, but some details are determined by the system.

The speed command could be a potentiometer, a number from a UART, or could be the output of another sensor.

These are the basic building blocks of the Motor Control kit we will introduce.

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Closed Loop Speed Control

� The way the loop works is to first measure the difference between the commanded speed and the actual speed

� If the speed is to low, the PI controller increases the PWM duty which sends more voltage to the motor, correcting speed

� If the speed to too high, the PI controller reduces the PWM, reducing the average voltage, so the motor slows down to the correct speed

� The Proportional and Integral parameters have to be tuned to optimized the speed loop response-prevent speed oscillations

Hall

Sensors

Speed

Calculation

Motor

PWM

Generation

PI

Controllerω*

ω θ

The same principles of closed loop apply to torque and position as with speed. The sensors are different, but the loops are calculated the same way. They may also differ in the required bandwidth. Normally current is the innermost loop, then outside will be speed or position.

When using position control, and by calculating reasonable position changes with time, speed is controlled without using a separate loop.

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Motor Kit for Trapezoidal Control

� BLDC Motor, Board, Software, Schematics, Tool and GUI

R8C/25

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Motor Control Evaluation Kit

� In order to help users decide on what kind of motor control they need, Renesas has introduced the YMCRPR8C25 Motor Control Evaluation Kit

� The kit includes all that is needed to try Hall and BEMF commutated Brushless DC motor control with closed speed loops including, the control board, motor, debugger, power supply and software

Introducing the YMCRPR8C25 Motor Control Evaluation Kit. Shown are the contents of the kit, minus the CD and user guide, but they are included. Really, almost everything you need is included and it has all the source code to operate in different modes.

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YMCRPR8C25 Block Diagram

The kit is based on the R8C Tiny family of microcontrollers, which have many features useful in 3-phase motor control.

Included on the board are all the power and signal circuitry needed to support the MCU in controlling the BLDC motor.

Take a moment to look at this, and keep in mind it is referenced in the other presentations and labs.

Lets get into more details of the board functions…

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Motor Control Board

� IGBT module capable of 10 amps.

� 3-Phase output capable of running DC and BLDC motors

� 15V and 5V regulators on board.

� Voltage input from a single 24V (18-36VDC) supply, no shock hazard.

This shows the power capabilities of the board, showing the input range, and the current capability of the transistors.

With special modifications, this power range can be expanded by connecting the PWM channels to an external transistor bridge and separate power source.

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Board User Interface

� Large potentiometer for speed control setting

� 2x8 LCD display with contrast pot for monitoring speed, current, etc.

� Four push-buttons

� Bus voltage monitoring to MCU

� Current monitoring to the module for automatic protection

The wide range of user interfacing makes it easy to use, even without a host PC. The board acts like many popular motor control systems you might find on the market, with forward, reverse and stop buttons, and a speed setting pot. The LCD shows the commanded and measured speed information in real time, as well as fault status codes.

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Commutation Options

� Back-EMF detection comparators

� Jumper selection (no soldering) between Hall and BEMF modes

� Input connector for Hall signals from motor

Shown are the two modes, for both Hall Commutated and BEMF commutated. But, with other software, sinusoidal commutation, using the halls as feedback, is also possible and that free code is available for download.

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Debugging Capabilities

� Optically Isolated RS-232 communication

� Optically Isolated E8(a) connector

� Prototyping areas (under LCD)

� LED’s for monitoring PWM lines, and GPIO

� Abundant test points

Knowing that the board will be used to develop custom motor applications, we provided as much access for the user as we could. This can help debugging motor signals, communication, GPIO, etc. We made sure the debugger and UART were optically isolated to show the importance of doing this in your own application. We ALWAYS recommend using isolated debugging with motor control applications.

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Motor Control Graphical User Interface

Stop

Target Speed Actual SpeedSpeed Slider

Motor

Current

System

Status

Included in the kit is the software for controlling the motor from the PC. This can help in getting even more performance data in real time. All the controls there to do full motor control, with the added benefits of the graphical display of Speed, Current, Voltage, Temperature, as well as fault status. This streaming data can be captured and stored in a file for detailed analysis.

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HEW Development Environment

Source Code Editor

Output Window

Pro

ject

Navig

ato

r

Renesas’ High Performance Embedded Workshop provides the entire environment for software development.

From here, you can edit your C code, compile, download to the chip and do on-chip debugging. The free 64k version is included with the Motor Control kit.

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Summary

� DC and BLDC motors were compared

� BLDC motors were shown to offer better performance

� A large number of applications are moving from other motor

types to BLDC motors

� Electronic BLDC motor control can be as simple as six-step

or as complicated as Vector Control

� Closed Loop Speed Control was explained

� The Renesas BLDC Motor Control Evaluation Kit was

introduced as a way to help get started in BLDC motor

control development

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Questions?

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Appendix

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WiFiSH, RX, R8C

High-end

ConnectivityV850ESV850ES

50MHz50MHzSHSH--2A2A200MHz200MHz

Ultra Low

Power78K078K010MHz10MHz

78K0R78K0R20MHz20MHz

V850ESV850ES20MHz20MHz

R8CR8C20MHz20MHz

M16CM16C32MHz32MHz

R32CR32C50MHz50MHz

Application Focused Solutions

TFT LCD

ControlH8S/SXH8S/SX

50MHz50MHz

SHSH--2A2A200MHz200MHz

General

Purpose 8-b

it

16-b

it

32-b

it

Renesas MCU and MPU Solutions

32-b

it32-b

it32-b

it

8-b

it

16-b

it

Application

ProcessorSHSH--33200MHz200MHz

SHSH--44240MHz240MHz

SHSH--4A4A600MHz600MHz3

2-b

it

32-b

it32-b

it

32-b

it32-b

it

32-b

it

32-b

it

Motor ControlSH, V850, RX,

78K0R, R8C

Capacitive Touch

R8C

Industrial CANR8C, R32C, SH

Lighting78K0

RX600RX600100MHz100MHz

RX600RX600100MHz100MHz

From the 8-bit R8C running at 20MHz to the superscalar performance of the SH-4A running at 600MHz, Renesas offers a broad portfolio of microcontroller and microprocessor solutions. The RX family operates at up to 100MHz and with its 165 DMIPS plus floating-point unit and digital signal processing capabilities is ideal for many 32-bit microcontroller, digital signal controller, and digital signal processing applications. The RX600 is also enabled with support for many application focused solutions such as WiFi and Motor Control making it extremely easy for users to adopt these technologies when developing with the RX platform.

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43

Motor Control Applications & Renesas Solutions

High-EndLow-Range Mid-Range

SPEED + TORQUECONTROL

SPEED CONTROLSPEED + DYNAMIC TORQUE

+ MOTION CONTROL

Fans, Kitchen Appliances,Pumps, Power-Tools

Pool Pumps, WashersHealth-Equipment

Compressors

MedicalIndustrial, Washers,

CompressorsMotion Control

Torque Control (Limited)

R8C

78K0R

SuperH

V850

RX

Renesas provides solutions for all types of motors – low range, brushed DC, stepper motors to high-end servo using BLDC and PMSM motors. Renesas also provides IEC60730 software solutions. This presentation does not cover IEC features. If interested, request the latest IEC presentation from RTA Marketing.

Page 44: ID 610C: Introduction to BLDC Motor Control

44

Renesas Motor Control Solutions

� Renesas covers every motor control application from low-

end to high-end

� Renesas can provide all motor algorithms from Trapezoidal

control to Sensor-less Vector control

� Wide product portfolio

� 16bit MCU (20MHz): R8C, 78K0R

� 32bit MCU (48MHz to 200MHz): RX, V850, SH

� These products have peripherals dedicated for Motor

Control such as Timers and ADC

44

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45

45

Motor Control Solution Summary

Motor Type Algorithm R8C 78K0R V850 RX

SH2/

SH2A

1-Ø ACIM (PSC) V/f, Open Loop Y

1-Ø BLDCFixed Duty (Hall) Y

Closed Loop (Hall) Y

Universal (Brushed) DC

TRIAC Control ( speed loop w/Tachometer) Y

PWM Chopper (speed loop w/Tachometer) Y

3-Ø ACIM

V/f, Open Loop Y Y

Speed Loop w/Tachometer Y

Sensorless Vector Control Y Y Y

3-Ø BLDC

120-deg Trapezoidal (Hall) Y Y

120-deg Trapezoidal (BEMF) Y

180-deg Sine (HALL) Y

Sensor based Vector Control Y Y

Position Control (Encoder + Hall) Y

Sensorless Vector Control,

2 DCCT, 3-shunt, 1-shunt Y Y Y Y*

*

*

*: Under development

Vector control, through frame transformation, decouples three-phase stator currents into two-phase dq-axis rotor currents, one that produces flux and the other that produces torque. Such a formulation makes it possible to control motor flux and torque directly (similar to a DC motor) so that fast dynamic response and excellent steady-state performance can be achieved.

This is three-phase synchronous system, the three AC currents generate a rotating flux. First transformation is to equivalently project 3-phase AC currents in 3-axis system into 2-phase orthogonal AC currents in the 2-axis e stationary frame. 3-phase and 2-phase AC currents in the same stationary frame produce the same torque. The second transformation is frame transformation. If the 2-axis frame is rotating which is the same as the 2-phase AC currents, the 2-phase AC currents should become the DC constants.

The goals of vector control formulation are to transfer these nonlinear equations into linear equations and decouple the three-phase stator currents into a flux component and a torque component. When his is done, torque and flux can be controlled directly, in the same way that it’s done to control a separately excited DC motor. In fact, the vector control uses vector equations and rotor orientation to transform the coupled three-phase AC motor model into a linear model that’s very similar to the linear motor model of DC motor. It enables the performance of BLDC motor drives to be comparable or even superior to that of DC motor drives [6-12].

Therefore,

•Through frame transformation, vector control converts AC motor into DC motor control

•Provide direct control of motor flux and torque

•Deliver optimal dynamic and steady performance

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