This paper presents a high step-up DC-DC converter for low voltage sources such as solar cells, fuel cells and battery banks. A novel non isolated Zero-Voltage Switching (ZVS) interleaved DC-DC boost converter condition is introduced. In this converter, by using coupled inductor and active clamp circuit, the stored energy in leakage inductor is recycled. Furthermore, ZVS turn on condition for both main and clamp switches are provided. The active clamp circuit suppresses voltage spikes across the main switch and the voltage of clamp capacitor leads to higher voltage gain. In the proposed converter, by applying interleaved technique, input current ripple and also conduction losses are decreased. Also, with simple and effective method without applying any additional element, the input ripple due to couple inductors and active clamp circuit is cancelled to achieve a smooth low ripple input current. In addition, the applied technique in this paper leads to increasing the life cycle of circuit components which makes the proposed converter suitable for high power applications. Finally an experimental prototype of the presented converter with 40 V input voltage, 400 V output voltage and 200 W output power is implemented which verifies the theoretical analysis.

In this paper, a new single soft switched forward converter with a self driven synchronous rectification (SDSR) is introduced. In the proposed converter, a soft switching condition (ZCS turn on and ZVS turn off) is provided for the switch, by an auxiliary circuit without any extra switch. In additional, this auxiliary circuit does not impose high voltage or current stresses on the converter. Since the proposed converter uses SDSR to reduce conductive loss of output rectifier, the rectifier switches are switched under soft switching condition. So, the conductive and switching losses on the converter reduce considerably. Also, implementing control circuit of this converter is very simple, due to the self-driven method employed in driving synchronous rectification and the converter is controlled by pulse width modulation (PWM). The experimental results of the proposed converter are presented to confirm the theoretical analysis.

In this paper, a non-isolated bidirectional DC-DC converter with zero voltage switching and constant switching frequency is proposed. Unlike the active clamp bidirectional converters, to create soft switching condition in both direction, only one auxiliary switch is used, which reduces conduction losses and the complexity of the circuit. The proposed converter is controlled by pulse width modulation and the switches are gated complementary, thus the implementation of the control circuit is simple. Low switching losses, high efficiency, high power density, are the advantages of this converter. The simulation and experimental results of the converter verify theoretical analysis. Based on an implemented prototype of the proposed converter at 80 watts, the measured efficiency is 96.5%.