IPD, POD and APOD Multi-carrier PWM Techniques for Five-Level Nested Neutral Point Clamped Inverter

Abstract

Recently, in order to develop high-voltage and large-capacity applications in industry and in the power grid, the NNPC type high-order inverter has been proposed. Simultaneously, pulse width modulation (PWM) control methods for these converters are also focused on research to provide high quality output voltage and current such as small current ripple, low harmonic distortion. Multi-carrier pulse width modulation (CBPWM) is an option due to its simplicity and ease of implementation. This paper studies the CBPWM techniques applied to the NNPC 5-level inverter. CBPWM techniques include in-phase disposition (IPD), phase opposition disposition (POD), and alternative phase opposition disposition (APOD). Because the inverter uses many flying capacitors, the problem of voltage balancing on the capacitors will be taken care of. The output voltage and current quality results of the load when using the CBPWM carrier methods: IPD, POD, APOD and applying the voltage balancing algorithm of the flying capacitors will be verified and evaluated. Simulation results with PLECS software. Finally, verification results from the experimental model of the 5-level NNPC inverter will confirm the correctness of the theoretical analysis and the designed capacitor voltage balancing algorithm.