PPT OF BLDC

Presented ByTANIA MITRA

CONTENTSINTRODUCTIONWORKING OF MOTORBRUSHLESS MOTORWORKING OF BLDCTESTING ANDTUNING ADVANTAGES OF BLDC MOTOR

INTRODUCTIONWhat is Motor?It is a machine can converts electrical energy to mechanical energy.It may be DC or AC depending upon the type of power supply.It has mainly two parts- stator & rotor.DC motors are of two types-Brushed motor with brushes and commutator andBrushless motor- without brushes.

INTRODUCTIONWhat is commutator and brush ? Commutator is a cylindrical in structure, made of copper or carbon with high conductivity.Mounted on the rotor part of the brushed motor.Helps to conduct current through conductor when the brushes comes to contact during rotation.The electrical contacts to the rotating ring called brushes.

Construction of Motor

General physics of motor

Working Principle

BRUSHLESS MOTORIt has no brushes and commutators.The rotation of the rotor depends on the accurate position with stator.Detected by Hall Sensor, mounted on rotor, shifted at 60 or 120 phase shift.Electronic commutation used to vary the PWM duty-cycle for speed control, using software.

Working of BLDC motorAs there is no commutator ,the current direction of the conductor on the stator controlled electronically.Rotor consists the parmanent 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 BLDC motorBrushless DC motor requires external commutation circuit to rotate the rotor.Rotor position is very important.HALL SENSOR senses the position of the coil accurately

Hall Sensor operationIt embedded into the stator on non-driving end of motor.Senses accurate position of the rotor to the stator.Shifts at 60 or 120 phase shift for each of three coils, yet a time two coils work for 3 current Due to the changing of direction of the current & applying Flemings Left Hand rule force direction can be determined.Thus the permanent magnet on rotor moves clockwise , as well as the rotor of the BLDC also moves clockwise.

Hall Sensor operation (contd.)

Output of Hall Sensor

PWM requirementTo control the speed PWM is required. To vary the speed the Hall output signals should be pulse width modulated.When the signals marked by PWM switches ON or OFF according to the sequence, the motor will run at the rated speed. The PWM frequency should be at least 10 times of the max. frequency as thumb rule.By varying duty cycle, the stator voltage can be increased causes increasing of the speed.

Machine rated speed 1000rpm, commutated with 6 pulsesRequired frequency f= 10006 = 6000 pulse/min.Therefore, speed in pulse/sec= 6000/60= 100 Hz. And the PWM frequency= 10100 Hz =1kHz.

Thus the speed depends on the switching frequency i.e. switching period.By varying duty cycle PWM freq. varies and switching speed also varies.It is controlled by electronically through software PEWIN32PRO in GMRT rayshed.

Brushless Servo motor

SERVOSTAR (used in GMRT Rayshed)

Minimum wiring for Driving Test

Testing Procedure

Testing Procedure (contd.)

TUNING of BLDC in GMRT RAYSHEDPMAC Programmable Multi Axis Controller.Commanding upto 8 axes of motion simultaneously. Three axes for Azimuth axis control , another three axes for Elevation axis control & rest 2 for future use.Each axis control part contains one feedback port also.It is set to the SERVOSTAR through PEWIN32PRO software.

Position and Velocity loop control

PMAC can be configured as two loops: 1. position loop2. velocity loop

PMAC configured as Position Loop

PMAC 1st axis connected to motor1 through servostar #1 as well as 2nd also connected to motor2 through servostar #2.Both the motors coupled through central gear and connected to the encoder.Encoder feedback connected to 5th axis of the PMAC.Commands for position loop #1o0 #2o0 #5o0 (enabling 1st, 2nd and 5th axis)#5j+ (closing the position loop)

PMAC configured as Velocity LoopFor making PMAC configured as velocity loop, position feedback need to be zero.Thus in below diagram 5th axis is zero.Command for velocity loop: #1o0 #2o0 #5o0 #7o0(enabling 1,2 5 & 7 axis) #5j/ (closing feedback)

Note: 7th channel taken for encoder data.

Programmable Multi Axes Controller (PMAC)

PMAC connected with SERVOSTAR & MOTORS

Advantages of Brushless MotorIn BLDC motor PM are on the rotor & electromagnets are on the stator controlled by software. Thus the advantages are:

Because of computer control it is more precise & more efficient.There is no sparking & less electrical noise.Voltage and current rating is high.High speed can be achieved.As there is no brushes it requires no servicing.It has longer life.Low Radio Frequency Interference and Electromagnetic Interference.

GMRT ANTENNA

GMRT ANTENNA ARRAY

SERVO MOTOR (at elevation) AT GMRT ANTENNA

Brushless DC motors at GMRT Rayshed

Brushless motors at GMRT Rayshed

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PPT OF BLDC