US 11,777,435 B1
Smooth transition control between overmodulation and six step pulse width modulation
Yang Sun, Noblesville, IN (US); and Caleb Secrest, Noblesville, IN (US)
Assigned to BorgWarner Inc., Auburn Hills, MI (US)
Filed by BorgWarner Inc., Auburn Hills, MI (US)
Filed on May 17, 2022, as Appl. No. 17/663,733.
Int. Cl. H02P 27/08 (2006.01); H02P 23/14 (2006.01)
CPC H02P 27/08 (2013.01) [H02P 23/14 (2013.01)] 20 Claims
OG exemplary drawing
 
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.