This paper presents a hybrid-type full-bridge dc/dc converter with high ability. Using a hybrid control design with a simple circuit design, the planned dc/dc converter has a hybrid operation mode. Under a normal input range, the planned converter perform as a phase-shift full-bridge series-resonant converter that supply high ability by applying soft switching on all switches and rectifier diodes and reducing conduction losses.
When the input is lower than the normal input range, the converter operates as an active-clamp step-up converter that improve an operation range. Due to the hybrid operation, the planned converter operates with larger phase-shift value than the conventional converters under the normal input range.
Thus, the planned converter is capable of being plan to give high power conversion ability and its operation range is lengthy. A 1-kW prototype is start to confirm the theoretical analysis and validity of the planned converter.
- Active-clamp circuit
- Full-bridge circuit
- Phase shift control.
Fig. 1. Circuit diagram of the proposed hybrid-type full-bridge dc/dc converter.
EXPECTED SIMULATION RESULTS:
Fig. 2. Experimental waveforms for the gate signals and output voltage according to the operation mode. (a) PSFB series-resonant converter mode when Vd = 350 V. (b) Active-clamp step-up converter when Vd = 250 V.
Fig. 3. Experimental waveforms for soft switching in the PSFB series resonant converter mode. (a) ZVS turn-on of S1 . (b) ZVS turn-on and ZCS turn-off of S2
.Fig. 4. Experimental waveforms for the current stress when Vd = 350 V. (a) Conventional PSFB series-resonant converter. (b) Proposed converter.
Fig. 5. Experimental waveforms for the input voltage Vd and output voltage Vo in the transition-state.
The novel hybrid-type full-bridge dc/dc converter with high ability has been introduced and verified by the analysis and experimental results. By using the hybrid control scheme with the simple circuit structure, the planned converter has both the step-down and step-up functions, which ensure to cover the wide input range.
Under the normal input range, the planned converter produce high ability by providing soft switching method to all the switches and rectifier diodes, and reducing the current stress. When the input is lower than the normal input range, the planned converter provides the step-up function by using the active-clamp circuit and voltage doubler, which extends the operation range.
To confirm the validity of the planned converter, 1 kW prototype was built and tested. Under the normal input range, the conversion ability is over 96% at full-load condition, and the input range from 250 to 350 V is guaranteed. Thus, the planned converter has many advantages such as high ability and wide input range.
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