An Overmodulation Strategy Based on a Generalised Duty Cycle Solution for Three- Phase Inverters

This paper extends a two-level three-phase pulse width modulation technique recently developed to synthesise reference voltages in the overmodulation interval. The method is based on a generalised analytical solution of the voltage-time law derived with the reference voltage in the stationary frame and the duty cycles. The strategy compensates the magnitude of the target voltage with a proposed preprocessor, which has been developed to work also with the duty cycles. The architecture enables the generation of output voltages in the two well-known overmodulation zones up to the six-step operation with a simple and fast algorithm. The modulator is validated with simulation and experimental tests, demonstrating a good response in the time domain and voltage/current spectra with a low amount of undesired harmonics.