AC/DC Converter Based on Instantaneous Power Balance Control for Reducing DC-Link Capacitance

抄録

In AC/DC converters for on-board chargers, the DC-link capacitor on the output side in a power factor correction (PFC) converter uses aluminum electrolytic capacitors in order to obtain a large capacitance for a low voltage ripple and small size. On the other hand, it is desirable to use a film capacitor instead of the aluminum electrolytic capacitors in order to obtain a long lifetime for the DC-link capacitor. However, the DC-link capacitance must be reduced as compared with the aluminum electrolytic capacitors in order to avoid increasing the size of the DC-link capacitor. This paper presents a control strategy for the AC/DC converter with a reduced DC-link capacitance. This strategy is based on the instantaneous power balance of a PFC converter and a DC/DC converter, and it controls the AC-side input current without being affected by the large ripple voltage of twice the utility line frequency owing to the reduced capacitance. The simulation and experimental results are presented to validate the proposed strategy, and it is confirmed that it is possible to reduce the DC-link capacitance to one-fifth when compared with the conventional AC/DC converter, without additional circuits.