Patent ID: 8446117
Filing Date: 2013-05-21
Classification: H02P

Abstract:
1. A method for controlling a multi-phase electric machine that is operating in an overmodulation region, the method comprising: determining sector boundary information for a current sector that defines an angular span between two adjacent voltage switching vectors that are used to generate pulse width modulated (PWM) waveforms of switching vector signals that drive switches in a five-phase inverter module, wherein the sector boundary information comprises: a sector boundary starting angle of the current sector, and a sector boundary ending angle of the current sector; computing an angular span of a current PWM period based on a switching frequency of a PWM generator and a particular instantaneous speed of the multi-phase electric machine, and forecasting a forecasted angular span of a next PWM period before the next PWM period occurs based on the angular span of the current PWM period; computing a plurality of transition angles based on the sector boundary information and a hold angle that is provided from an overmodulation processor; determining whether any of the transition angles occur within the forecasted angular span of the next PWM period; computing, when any of the transition angles are determined to occur within the forecasted angular span of the next PWM period, a duty cycle compensation for the next PWM period that is used to adjust the duty cycle for the PWM waveforms of the switching vector signals that will be generated during the next PWM period; and applying the computed duty cycle compensation when generating PWM waveforms for the next PWM period before the next PWM period occurs to adjust the duty cycle the next PWM period.