A hybrid PWM strategy combining modified space vector and triangle comparison methods

Abstract

Classical space vector PWM with equal duration of application of zero state vectors V0 and V7 was modified. The time of application of vector V7 (and V0) was made changeable from 0 to 100% over the time T/sub 0/ for their combined application. The ratio of the duration of application of vector V0 vs. V7 can be kept constant or changed on a sample by sample basis with a significant impact on the characteristics of the PWM. Correlation between modified space vector and triangle comparison methods was established. It was proved in the paper that modified space vector PWM (with a classical space vector PWM as a special case) can be implemented as a triangle comparison method with added zero sequence. A new algorithm suitable for implementation of modified space vector method on digital or analog hardware for triangle comparison PWM was proposed. Because the algorithm combines the theory of space vector PWM with ease of implementation of a triangle comparison PWM it was named "hybrid" PWM (HPWM).