Analysis of a hybrid PWM based on modified space-vector and triangle-comparison methods

A classical space-vector pulsewidth modulator (PWM) with equal duration of application of zero-state vectors V-0 and V-7 was modified, A factor-variable k(0) (proportional to the time of application of vector V-7) was introduced. By changing Lo from zero to one, the duration of application of V-7 can be changed from 0% to 100% of the combined application time for zero-state vectors, Correlation between modified space-vector and triangle-comparison methods (with added zero sequence) was established, The influence of factor k(0) on characteristics of the PWM was investigated. An expression for the optimal value of k(0) that provides minimum ripple in the load current was derived, Salient features of the new algorithm are extended linearity (up to a modulation index of 1.154), reduced switching losses, and ability to change the current spectrum by changing k(0) every sampling time, The developed algorithm is suitable for microprocessor and analog implementation, Since the new algorithm combines the theory of space-vector PWM with the ease of implementation of a triangle-comparison PWM, it is named ''hybrid'' PWM (HPWM).