Interleaved LLC Converter With Cascaded Voltage-Doubler Rectifiers for Deeply Depleted PEV Battery Charging

This paper proposes an interleaved Inductor-Inductor-Capacitor resonant converter with cascaded voltage-doubler circuits for deeply depleted plug-in electric vehicle battery charging. The use of voltage double circuits extends the operating range of converter by mitigating the effects of transformer's parasitic capacitors. The converter has two modes of operation: simultaneous and independent. In the former mode both interleaving converters operate together at the same frequency and in the later mode only one converter operates. In the former mode, it yields twofold higher gain compared to the later one. Thus, operation with combined mode changing and frequency control results in wider output voltage range. For confirmation, a laboratory prototype rated at input dc voltage of 400 V and output power of 1.5 kW is designed, and implemented. The results obtained from the prototype show that converter achieves a wide output voltage range of 100-420 V when operated in simultaneous mode with simple frequency control and an output voltage range of 50-100 V in the independent mode. With combined frequency and mode changing control, it achieves an output range of 50-420 V. The peak efficiency of converter was measured to be 95.65% at a peak power of 1.5 kW. Thus, the proposed converter is suitable for the dc-dc stage of on-board PEV battery charger.