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BRUSHLESS MOTOR COMMUTATION. PRESENTATION BY SWAPNA.M. PRESENTATION OUTLINE. OBJECTIVE THE BRUSHLESS DC (BLDC) MOTOR COMPARISON OF BLDC MOTOR & BRUSHED MOTOR ADVANTAGES OF BLDC MOTOR METHODS OF COMMUTATION TRAPEZOIDAL COMMUTATION SINUSOIDAL COMMUTATION. OBJECTIVE.
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BRUSHLESS MOTORCOMMUTATION PRESENTATION BY SWAPNA.M
PRESENTATION OUTLINE • OBJECTIVE • THE BRUSHLESS DC (BLDC) MOTOR • COMPARISON OF BLDC MOTOR& BRUSHED MOTOR • ADVANTAGES OF BLDC MOTOR • METHODS OF COMMUTATION • TRAPEZOIDAL COMMUTATION • SINUSOIDAL COMMUTATION
OBJECTIVE • To investigate different methods of commutation of BLDC motor-Trapezoidal & Sinusoidal
The Brushless DC (BLDC) Motor • A modern, much improved, version of the traditional brushed DC motor. • An inside out DC motor with electronic commutation • Field- permanent magnets- is on the rotor. • Armature- is on the stator which has good cooling. • Two types of motor sinusoidal trapezoidal
Sinusoidal motor • Sinusoidal distribution of magnetic flux • 2. Sinusoidal current waveforms • 3. Sinusoidal distribution of stator conductors. • Trapezoidal motor • Rectangular distribution of • magnetic flux • 2. Rectangular current waveform • 3. Concentrated stator windings. • Mechanical commutator of brushed motor replaced by electronic switching of the phases. • Switching - synchronised to absolute rotor position – smooth torque production.
Advantages of BLDC Motor • Better speed versus torque characteristics • High dynamic response • High efficiency • Long operating life • Noiseless operation • Higher speed ranges • Ratio of torque to size of the motor is higher ApplicationsAppliances, Automotive, Aerospace, Consumer, Medical, Industrial Automation Equipment and Instrumentation.
Commutation of BLDC Motor • Commutation – to energize the appropriate windings in the stator to provide optimum torque generation depending on the rotor position. • Methods of Commutation • Trapezoidal Commutation • Sinusoidal Commutation
Trapezoidal Commutation • Simplest method of control for dc brushless motors • Only two phase coils are active at any instant • Commutation –every 60 degree • Hall effect sensors are used
Merits1. Simple control circuits2. Switching loss is less3. Only one current at a time needs to be controlled.4. Only one current sensor is necessary.Demerits1. Overall system efficiency is poor2. Torque ripple is present at each 60 degree phase commutation 3. Inadequate to provide smooth and precise motor control
Sinusoidal Commutation • All three phases are active at any moment. • Attempt to drive - three currents that vary smoothly and sinusoidally as the motor turns • Smooth torque control & accurate position control is required. • An encoder is required