The Transactions of the Korean Institute of Power Electronics (전력전자학회논문지)

The Korean Institute of Power Electronics (전력전자학회)
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A Study on Bipolar DC-DC Converter for Low Voltage Direct Current Distribution

저압 직류 배전용 양극성 DC-DC 컨버터에 관한 연구

  • Lee, Jung-Yong (Dept. of Electrical Engineering, Konkuk University) ;
  • Kim, Ho-Sung (Power Conversion and Control Research Center, HVDC Research Division, KERI) ;
  • Cho, Jin-Tae (Smart Power Distribution Lab. Power Distribution ICT Group, KEPCO) ;
  • Kim, Ju-Yong (Smart Power Distribution Lab. Power Distribution ICT Group, KEPCO) ;
  • Cho, Younghoon (Dept. of Electrical Engineering, Konkuk University)
  • Received : 2018.09.22
  • Accepted : 2018.11.05
  • Published : 2019.08.20
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Abstract

This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.

Keywords

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Fig. 2. Configuration of LVDC (a) Unipolar, (b) Bipolar.

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Fig. 3. Proposed bipolar DC-DC converter topology.

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Fig. 4. Voltage balancer operating waveform.

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Fig. 5. Current path of voltage balancer (a) Mode 1, (b) Mode 2.

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Fig. 6. Proposed bipolar DC-DC converter topology.

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Fig. 7. Control strategy (a) for voltage balancer, (b) for bipolar DC-DC converter.

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Fig. 8. The output waveform of voltage balancer in unbalance load condition.

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Fig. 9. The simulation results of LVDC DC-DC converter (a) Under balance load condition, (b) Under unbalance load condition.

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Fig. 10. The LVDC bipolar DC-DC converter prototype.

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Fig. 11. Experimental results under 9kW balance load condition.

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Fig. 12. Experimental results under 4.5kW unbalance load condition.

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Fig. 13. Efficiency measurement result of the prototype.

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Fig. 1. Configuration of solid state transformer for LVDC.

TABLE Ⅰ SYSTEM PARAMETERS OF PROPOSED CONVERTER

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TABLE Ⅱ SYSTEM PARAMETERS

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TABLE Ⅲ DESIGNED INDUCTOR PARAMETERS

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References

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