Research on voltage-balanced asymmetric multi-level inverter for motor's speed control

Nowadays,multi-level inverter technique is already widely used in the high-voltage and high-power field.Meanwhile the hybrid asymmetric 6-level inverter has been focused on for its simple construction and waveforms without 0 level.However,we all know that mid-point voltage control is one of the technical difficulties to high-voltage high-power multi-level inverter circuit.So a new single-phase hybrid asymmetric 6-level inverter is researched in this paper.In the inverter a 3-level Half-bridge unit and a Half-bridge unit are cascaded to form an inverter phase leg.This kind of construction can make the mid-point voltage balance without any other special circuit and complicated control methods.Meanwhile,6-lever will be put out at the end of the circuit.The EPWM control method is proposed considering the construction of the inverter.The experiment on the voltage-balanced asymmetric 6-level inverter for motor's speed control is carried out and the ideal output waveforms show the feasibility of the construction and the reasonableness of the EPWM method.