Full-Si-Based Two-Stage VSI and Its Specialized Modulation Strategy to Reduce Switching Power Loss and Increase PWM Harmonic Frequency

This article proposed a full-Si-based two-stage voltage source inverter (VSI) along with its specialized modulation strategy aimed at reducing switching power loss and increasing pulsewidth modulation (PWM) noises frequency. In full-Si-based VSIs, PWM-induced high-frequency electromagnetic noise is an inherent limitation in motor drive applications. Although increasing PWM frequency can mitigate these noises for inductive loads, it also leads to higher switching power loss. To reduce the ratio of switching power loss to PWM frequency, the proposed two-stage VSI, comprising eight insulated-gate bipolar transistors (IGBTs) and utilizing the specialized modulation strategy, creates zero-voltage-switching and zero-current-switching conditions without relying on resonant circuits. The effectiveness of this approach has been verified through experiments conducted on a prototype driving a 5.0 kW sensorless interior permanent magnet synchronous motor. For conventional space vector PWM, increasing the PWM frequency by 1 kHz adds 16.8 W of inverter power loss. In contrast, for the specialized modulation strategy in the proposed two-stage VSI, increasing the PWM frequency by 1 kHz only adds 9.1 W of inverter power loss. Experiments verify a significant reduction in the ratio of switching power loss to PWM frequency, enabling higher PWM frequency to effectively suppress harmonic distortion and acoustic noise in inductive loads.