Output Voltage and Current Waveforms' PSIM Simulation of Three-Phase Seven-Level Cascaded H-Bridge Inverter

The paper considers a PSIM model of the seven-level cascaded H-bridge voltage source inverter, including a control circuits of its power switches (on the base signals' level). This simplified PSIM model is intended only for the investigation of the inverter output voltages and currents quality (the harmonic content, namely voltages' and currents' THD and voltages' weighted THD), since the used here first level of the model supposes a simple and strict correspondence between coordinates of specified space vectors' and the power switches' states. A way of using this kind of PSIM models with minimum changes for simulation of multilevel voltage source inverters (MLVSI) under both the carrier-based PWM and some kinds of space vector PWM is demonstrated. By way of illustration the dependences of some of the above mentioned harmonic coefficients on the amplitude modulation index are shown and the approach to supplementing the inverter model control circuit for the common-mode voltage minimization and the related waveforms are presented.