In this paper, a high-efficiency DC/DC converter with low voltage stress is designed for green power applications. The proposed non-isolated high step-up DC/DC converter combines the advantages of switched capacitors, coupling inductors, and voltage multiplier techniques. Adding the cells of the switched capacitor not only increases the voltage gain but reduces the voltage stress of the semiconductor devices. High voltage gain can be achieved by adding a coupled inductor method to adjust the turns ratio. When these are combined with a voltage multiplier circuit, the leakage energy of the coupled inductor is recirculated to the output terminal with lossless passive clamping performance. The leakage inductance of the coupled inductor controls the current dropping rate of the output diode turn OFF so that the reverse-recovery problem is mitigated. The proposed converter integrates these three techniques to achieve high voltage gain without operating at maximum duty cycle. In addition, switching loss reduction is realized through zero current switching turn ON soft switching performance with low voltage stress of semiconductor devices. Finally, this paper verifies the performance of the proposed converter for theoretical analysis by using a 35~45V input, 380V output, and 1kW power prototype circuit. INDEX TERMS Boost converter, high step-up, coupled inductor, switched capacitor, voltage multiplier cell.

An improved high step-down DC-DC converter for charging the batteries in an electric vehicle application is proposed in this paper. It adopts the topology of the conventional full-bridge converter, which has a coupled inductor current-doubler rectifier as the secondary side of the transformer. In addition, four power switches are driven using a phase-shifting technique. The proposed converter can achieve a high step-down voltage with low-voltage stress on the rectifier diodes. In addition, the coupled inductor current-doubler rectifier of the secondary side can reduce the ripple current and losses of the secondary side to achieve high efficiency. Furthermore, the proposed converter can overcome the drawbacks of the conventional full-bridge converter, such as switching loss caused by high switching frequency, duty-cycle loss, voltage stress, and numerous components, and can increase the efficiency with the soft-switching technique. A 600 W laboratory prototype of the proposed converter was manufactured. The results of the experiments performed with the prototype proved the effectiveness and validated the use of the proposed converter for better charging of electric vehicles.

No abstract

This paper proposes a high voltage step-up DC/DC converter by combining a coupled inductor and a voltage multiplier rectifier. The input side of the proposed converter operates in an interleaved manner with two coupled inductors connected in parallel, and the output side is composed of a voltage multiplier rectifier where two voltage doubler rectifiers are merged in series. By changing the turns ratio of the coupled inductor of the proposed converter, the voltage gain can be increased, and additional voltage gain can be obtained by combining it with a voltage multiplier rectifier. Due to the passive lossless clamping performance of the proposed method, it is possible to recycle the leakage inductance energy of the coupled inductor and voltage stress reduction can be achieved along with zero current turn-ON and turn-OFF of switches and diodes. Finally, this paper evaluates the effectiveness and practicality of the proposed method by operating a prototype circuit with an input voltage of 20V, an output voltage of 400V, and an output power of 320W. The maximum efficiency of the proposed converter is 97.2% and the efficiency at maximum power is 94.1%.INDEX TERMS DC/DC converter, high step-up, coupled inductor, voltage multiplier rectifier.

No abstract