Dynamic overmodulation characteristics of triangle intersection PWM methods

In this paper, the dynamic overmodulation characteristics of current regulated carrier-based high-performance PWM-VSI drives are investigated. Dynamic and steady state overmodulation operating modes are clearly distinguished, and the requirements for obtaining high performance in each mode are shown to be significantly different. Dynamic overmodulation characteristics of the popular triangle intersection PWM methods are modeled and shown to be unique for each method. The study reveals that space vector PWM (SVPWM) exhibits a minimum voltage magnitude error characteristic. It also indicates all the advanced triangle intersection PWM methods including SVPWM have limited dynamic overmodulation performance. To enhance the performance, an algorithm with superior performance is adapted from the direct digital PWM approach. Detailed induction motor drive simulations illustrate the deficiency of popular triangle intersection PWM methods and the performance gained with the new dynamic overmodulation algorithm.