Comparative analysis of fixed and sinusoidal band hysteresis current controllers for voltage source inverters

A hysteresis controller with a sinusoidal band for current regulation is described. The behavior of the conventional fixed-band controller and the proposed sinusoidal band controller has been thoroughly studied. Simulation results demonstrate that with no lockout (permitting a very high switching frequency) the current waveform can be confined within the desired hysteresis bands. At low lockout frequencies the current is not confined within the hysteresis bands and both fixed and sinusoidal band controllers give a high ripple. The study also shows that with a reasonable lockout frequency, a sinusoidal band control results in a reduced ripple and lower harmonic content. However, the switching frequency is higher with the sinusoidal bands. This should not be a major concern with the availability of fast switching devices that allow higher lockout frequencies