One-Cycle Control for Electrolytic Capacitor-Less Second Harmonic Current Compensator

The input power of the single-phase power factor correction ac-dc converter pulsates at twice the line frequency, while the output power of the single-phase dc-ac inverter pulsates at twice the output frequency. The pulsating power will result in second harmonic current (SHC) in the ac-dc converter and dc-ac inverter. In this paper, electrolytic capacitor-less second harmonic current compensator (SHCC) is presented to compensate the SHC. The SHCC has two operating modes, namely, charging mode and discharging mode. To achieve an excellent SHC compensation performance, a hybrid one-cycle control (OCC) is proposed to regulate the port current of the SHCC, and the SHCC can stably operate in both the charging mode and discharging mode. To avoid the mode detection required in the hybrid OCC and ensure seamless transition between the two modes, the OCC with dc bias is further proposed. Besides, a peak voltage control is proposed to regulate the storage capacitor voltage in the SHCC for reducing the power losses of the SHCC at light load. A 1-kW two-stage inverter with the SHCC is fabricated and tested, and the experimental results are provided to verify the effectiveness of the proposed control schemes.