CONTROL OF LOW-DISTORTION 27-LEVEL CASCADE INVERTER WITH ONLY THREE H-BRIDGE INVERTER MODULES

摘要

Traditional means for implementing a 27-level cascaded multilevel inverter needs the combination of 13 full-bridge inverter modules. This paper presents a novel control of 27-level cascaded inverter with only 3 full-bridge inverter modules. The switching angles of power switches in the traditional cascaded multilevel inverters are obtained by the use of Fourier series to minimize the voltage harmonic distortion. The traditional method is complicated and difficult to implement in a practical inverter. With the proposed method, the switching angles are transformed into the switching reference voltages of inverter switches, therefore, the control of switches for different load conditions is very easy to implement without complicated calculations. Simulations and experimental results are presented to demonstrate the performance of the proposed inverter.