Analysis and Comparison of Overmodulation Algorithms for Space Vector Modulated Voltage Source Inverter

Overmodulation increases the DC bus utilization in a voltage source inverter, but also requires significantly higher computational effort than linear modulation. The standard two-zone overmodulation algorithm and its two variants are analyzed and compared theoretically as well as experimentally in this paper All three algorithms maintain proportionality between the reference voltage and applied voltage up to the six-step mode. Compared to the standard algorithm, variant I reduces the computational overhead significantly, while increasing the harmonic distortion considerably. Variant-II, which is proposed here, reduces the computational burden further; the corresponding harmonic distortion is significantly lower than that of variant-I, and only moderately higher than that of the standard algorithm. The analysis of the three algorithms indicates the possibility of numerous overmodulation algorithms. A new overmodulation algorithm is designed for illustrative purpose. A generalized overmodulation algorithm is presented.