Brushless motor/sanjeet-1308143

Brushless Dc motor

Presented by:Sanjeet kumar

Registration No.-1308143Branch: Electrical & Electronics Engineering

Brushless Dc Motor• Brushless DC Motors are a type of

synchronous motor. magnetic fields generated by the stator and rotor

rotate at the same frequency no slip Has no brushes and commutators. Rotation of the rotor depends on the accurate

position with stator.

• Detected by Hall Sensor, mounted on rotor, shifted at 60º or 120º phase shift.

• Electronic commutation used to vary the PWM duty-cycle for speed control, using software.

• Available in single-phase, 2-phase, and 3-phase configurations

BLDC Motor Stator

BLDC Motor Rotors

Working of Brushless dc motor As there is no commutator ,the

current direction of the conductor on the stator controlled electronically.

Rotor consists the permanent magnet where as stator consist a no. of windings. Current through these winding produces magnetic field and force.

Hall sensor used to determine the position during commutation.

Commutation of BLDCM…

Brushless DC motor requires external commutation circuit to rotate the rotor.

Rotor position is very important.

HALL SENSOR senses the position of the coil accurately.

Working Procedure• When electric current passes through a coil in a magnetic field, the magnetic force produces a

torque which turns the motor.

• Force in Motor:• F=ILB• F = Force • B = Magnetic Field• L = Length of Conductor• I = Current in Conductor

• Torque in Motor:• T = IBA sin θ• A = LW• L = Length of Winding• W = Width of Winding

Hall-Effect

• If a current-carrying conductor is kept in a magnetic field, the magnetic field exerts a force on the moving charge carriers, tending to push them to one side of the conductor, producing a measurable voltage difference between the two sides of the conductor.

Hall-Effect Sensors

• Need 3 sensors to determine the position of the rotor

• When a rotor pole passes a Hall-Effect sensor, get a high or low signal, indicating that a North or South pole

Transverse Sectional View of Rotor

Commutation Sequence

• Each sequence has one winding energized positive (current into the

winding) one winding energized negative (current out of the

winding) one winding non-energized

Torque-Speed Characteristic

Advantage In BLDC motor PM are on the rotor &

electromagnets are on the stator controlled by software. Thus the advantages are:

1. Because of computer control it is more precise & more efficient.

2. There is no sparking & less electrical noise.

3. Voltage and current rating is high.4. High speed can be achieved.5. As there is no brushes it requires no

servicing.6. It has longer life.7. Low Radio Frequency Interference and

electromagnetic Interference.

Disadvantage

Requires Complex Drive Circuitry. Requires additional Sensors. Expensive. Some designs require manual labor.

(Hand wound Stator Coils)

Applications• PMBLDC motors are increasingly

being used in a wide spectrum of applications:

• domestic equipments,• automobiles• information technology equipment• industries• public life appliances • transportation• aerospace, defence equipments, power

tools, toys, vision and sound equipments • medical and health care equipment

ranging from microwatts to megawatts.

Presented By:Sanjeet Kumar

[email protected] +91-8968143473