TANIA MITRA

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BRUSHLESS MOTOR DRIVE

• Presented By
• TANIA MITRA

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CONTENTS

• INTRODUCTION
• WORKING OF MOTOR
• BRUSHLESS MOTOR
• WORKING OF BLDC
• TESTING AND
• TUNING
• ADVANTAGES OF BLDC MOTOR

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INTRODUCTION

• What 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 and
• Brushless motor- without brushes.

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INTRODUCTION

• What 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.

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Construction of Motor
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General physics of motor
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Working Principle
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Working Principle
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BRUSHLESS MOTOR

• It 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 60º or 120º phase shift.
• Electronic commutation used
• to vary the PWM duty-cycle for
• speed control, using software.

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Working of BLDC motor

• As 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.

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Commutation of BLDC motor

• 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

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Hall Sensor operation

• It embedded into the stator on non-driving end of
  motor.
• Senses accurate position of the rotor to the
  stator.
• Shifts at 60º or 120º phase shift for each of
  three coils, yet a time two coils work for 3F
  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.

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Hall Sensor operation (contd.)
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Hall Sensor operation (contd.)
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Output of Hall Sensor
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PWM requirement

• To 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.

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• Machine rated speed 1000rpm, commutated with 6
  pulses
• Required 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.

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TESTING of bldc in gmrt rayshed
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Brushless Servo motor
AKM series motor
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SERVOSTAR (used in GMRT Rayshed)
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Minimum wiring for Driving Test
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Testing Procedure
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Testing Procedure (contd.)
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Testing Procedure (contd.)
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Testing Procedure (contd.)
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Testing Procedure (contd.)
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Testing Procedure (contd.)
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Testing Procedure (contd.)
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TUNING of BLDC in GMRT RAYSHED

• PMAC 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.

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Position and Velocity loop control
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• PMAC can be configured as two loops
• 1. position loop
• 2. velocity loop

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PMAC configured as Position Loop
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• 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)

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PMAC configured as Velocity Loop

• For 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.

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Programmable Multi Axes Controller (PMAC)
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PMAC connected with SERVOSTAR MOTORS
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Advantages of Brushless Motor

• In 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.

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GMRT ANTENNA
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GMRT ANTENNA ARRAY
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SERVO MOTOR (at elevation) AT GMRT ANTENNA
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Brushless DC motors at GMRT Rayshed
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Brushless motors at GMRT Rayshed
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Thank You