Five-level Rectifier with Floating and DC-Link Capacitor Voltage Balancing

This paper presents a five-level unidirectional rectifier with active power factor correction, sinusoidal shaping of the input current, and output voltage control. The rectifier is characterized by automatic voltage regulation of floating and dc-link capacitors, which significantly reduces the control effort compared to conventional five-level rectifiers. This eliminates the need for additional active control strategies, external sensors, or circuits. Additionally, the proposed rectifier can operate with a lower dc-link voltage value than the peak grid voltage, thereby extending the output voltage range compared to conventional boost-type rectifiers. The operating principle, modulation strategy, and simulation results are provided to validate the proposal.