Improved hysteresis current control of multilevel inverters with constant switching frequency

Conventional hysteresis controllers have a major disadvantage of a variable switching frequency. This paper presents a variable hysteresis control method for implementing multilevel modulation of multilevel inverters with constant switching frequency, by using the current error zero crossing time to calculate the hysteresis bands in a switching period. This strategy makes algorithm independent of load parameters, and can be adapted to multilevel inverter with double-band and slope detection. Simulation results confirm the effectiveness of the proposed approach.