Novel Zero-CM Voltage Modulation With Dead Zone Compensation and Variable Dead Zone to Enhance the Ultimate Capability of Active EMI Suppression

The article analyzes the common-mode (CM) electromagnetic interference (EMI) in four three-phase two-level inverter parallel (FTTIP) system and proposes a novel zero-CM voltage (ZCMV) modulation strategy by equivalently treating each phase as a five-level system. It also analyzes the impact of dead zone, using ZCMV with dead zone compensation and random variable dead zone (ZCMVCR) to further enhance the ultimate capability of active EMI suppression. It also maintains output voltage balance to improve overall system performance. Simulation and experimental verification are conducted. The experimental results show that compared to traditional space vector pulse width modulation (SVPWM), ZCMVCR can reduce CM EMI by 10–25 dB in the range of 10 kHz–3 MHz. The variable dead-zone method can further reduce the CM EMI by 5–10 dB in high frequency range of 1–3 MHz on the basis regular ZCMV.