Novel adaptive hysteresis band modulation strategy for three-phase inverters

Analysis of hysteresis band modulation for three-phase inverters is used as a basis for developing a new discrete sampling-based PWM strategy. This sampling-based PWM strategy closely approximates the switching angles of the analogue hysteresis band modulation technique, but does not involve the solution of nonlinear transcendental equations, which are characteristic of the analogue method and therefore limit its application. The advantage of the sampling-based strategy is that the switching angles can be solved online and it is, therefore, inherently suited for a digital signal processor (DSP) implementation. Comparisons between the analogue hysteresis band PWM and the sampling-based strategy will be presented in terms of total harmonic distortion (THD) and harmonic spectra. Both simulation and experimental results are presented to confirm the theoretical analysis and show the advantages of the new strategy.