Control of brushless motor using rectified voltage where conduction period is updated in response to zero-crossing in alternating voltage

摘要

A brushless motor 2 is controlled by rectifying an alternating voltage to provide a rectified voltage and exciting a winding of the motor with the rectified voltage for a conduction period over each electrical half-cycle of the motor. The conduction period is updated in response to a zero-crossing in the alternating voltage. The conduction period may be adjusted in response to a change in motor speed or the RMS value of the alternating voltage. The control system 3 comprises a rectifier 8, DC link filter 9, inverter 10, gate driver module 11, current sensor 12, position sensor 13, zero cross detector 14, temperature sensor 15 and controller 16. Power to the system is provided by AC supply 4. The motor may comprise a four-pole permanent magnet rotor that rotates relative to a stator.