Dynamic space vector based discontinuous PWM for three-level inverters

Three-level diode clamped inverters have been widely used in high-voltage and high-power applications, which can effectively increase the voltage/current limit of power electronic devices. This paper proposes a dynamic space vector based discontinuous PWM (DSV-DPWM) to enhance the robustness to neutral point potential fluctuations (NPPF). The proposed method generates a dynamic space vector (DSV) by detecting the voltages across upper capacitor and lower capacitor of inverter in the real-time, which then accurately synthesizes the vector reference. In particular, gh-coordinate and parity sector conversion approach are adopted to reduce the complexity of DSV-DPWM. Moreover, switching vector sequence that has opposite effect on neutral point potential is employed to eliminate neutral point potential offset (NPPO). DSV-DPWM performance is thoroughly analyzed based on error current vector. Both PSCAD/EMTDC simulation and digital signal processor (DSP) based hardware experiment using TMS320F28335 chip have been undertaken, which verify the advantages of DSV-DPWM against traditional space vector based discontinuous PWM (TSV-DPWM).