CPC H02P 27/08 (2013.01) [H02P 23/14 (2013.01)] | 20 Claims |
1. A controller for controlling a voltage source inverter (VSI) electrically operatively connected between a DC voltage source and a multi-phase AC electric machine, the VSI including a plurality of selectively controllable switches that are activatable and de-activatable according to a space vector pulse width modulated (SVPWM) duty cycle with a rotating control voltage within an inverter voltage limit hexagon defining six sectors, the controller comprising a computing device and software, the computing device and software configured and operable to perform the following steps:
calculating a normal duty cycle for each phase of the AC electric machine;
determining the modulation index (MI) and comparing the MI to a predetermined threshold value MI_threshold;
if MI is less than or equal to MI_threshold, control one or more of the plurality of switches according to the normal duty cycle; and
if MI is greater than MI_threshold;
calculating a modified duty cycle based on an average ideal control voltage over a full PWM cycle; and then
controlling the one or more of the plurality of switches according to the modified duty cycle.
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