Control of Electric Motors

摘要

A control system for a multiphase electric motor comprises processing means arranged to determine a pattern of PWM voltage waveforms to be applied to respective phases of the motor, the processing means assigning different PWM patterns for use with different motor positions. In use for a given rotational position of the motor the processing means is normally adapted to apply PWM waveforms according to the assigned PWM pattern unless a different PWM pattern is currently in use at that time, except that in the event that the demanded voltage waveforms cannot be achieved with the current PWM pattern the processing means is adapted to force the PWM pattern to change. Upon the rotor moving into a different position associated with a different assigned pattern the processing means forces the PWM pattern to change to the assigned PWM pattern.

主权项

1. A control system for a multiphase electric motor comprising processing means arranged to monitor electrical currents in the motor and a rotational position of the motor and to determine PWM voltage waveforms to be applied to respective phases of the motor, the PWM voltage waveforms being arranged in a PWM pattern, wherein: the processing means assigns different PWM patterns for use with different positions or with a range of different rotor positions of the motor, and whereby in use for a given rotational position or range of rotational positions of the motor the processing means is normally adapted to apply PWM waveforms according to the assigned PWM pattern unless a different PWM pattern is currently in use at that time, except that in the event that the demanded voltage waveforms cannot be achieved with the current PWM pattern the processing means is adapted to force the PWM pattern to change; and further in which upon the rotor moving into one of the different positions or range of positions associated with a different assigned pattern the processing means is adapted to force the PWM pattern to change to the assigned PWM pattern.