| 摘要 |
A drive system for a multi-phase brushless motor comprises a single current sensor drive circuit, including switch means, switchable between a plurality of states. A controller is arranged to provide pulse width modulated drive signals to control the switch means so as to control the time that the drive circuit switches between said states in each of a series of pulse width modulation periods, and to: determine a demanded voltage parameter set, identify PWM periods during which the demanded voltage parameter set is such that neither two nominal corresponding state times, nor a higher number of equivalent state times producing the same net voltage, in a single PWM period, would allow a predetermined minimum time to be spent in a predetermined number of active states sufficient for current sensing. For such PWM periods, modified state times are calculated that do allow sufficient time to be spent in a sufficient number of active states for the current in each of the phases to be determined by means of the current sensor. |
