# Model-based Optimal Control Algorithm for the Clamp Switch of Zero-Voltage Switching DC-DC Converter

• Ahn, Minho (Department of Electrical and Computer Engineering, Ajou University) ;
• Park, Jin-Hyuk (Department of Electrical and Computer Engineering, Ajou University) ;
• Lee, Kyo-Beum (Department of Electrical and Computer Engineering, Ajou University)
• Accepted : 2016.12.13
• Published : 2017.03.20

#### Abstract

This paper proposes a model-based optimal control algorithm for the clamp switch of a zero-voltage switching (ZVS) bidirectional DC-DC converter. The bidirectional DC-DC converter (BDC) can accomplish the ZVS operation using the clamp switch. The minimum current for the ZVS operation is maintained, and the inductor current is separated from the input and output voltages by the clamp switch in this topology. The clamp switch can decrease the inductor current ripple, switching loss, and conduction loss of the system. Therefore, the optimal control of the clamp switch is significant to improve the efficiency of the system. This paper proposes a model-based optimal control algorithm using phase shift in a micro-controller unit. The proposed control algorithm is demonstrated by the results of PSIM simulations and an experiment conducted in a 1-kW ZVS BDC system.

#### File

Fig. 1. (a) BDC structure and (b) synchronous conduction mode(SCM) operation.

Fig. 2. Zero-voltage switching (ZVS) BDC and clamp switch.

Fig. 3. Key waveform of the buck operation.

Fig. 4. Equivalent circuits of ZVS BDC during buck operation.

Fig. 5. Key waveform of boost operation.

Fig. 6. Equivalent circuits of the ZVS converter in boost mode.

Fig. 7. Inductor current according to switching time.

Fig. 8. Block diagram of PI the controller and system.

Fig. 9. Block diagram of the proposed control algorithm.

Fig. 10. Phase shift method of ZVS BDC.

Fig. 11. Inductor current and gate signal of ZVS BDC.

Fig. 12. Waveform of the proposed control algorithm in buck operation

Fig. 13. ZVS of Stop within dead time (buck operation).

Fig. 14. Waveform of the proposed control algorithm in boost operation

Fig. 15. ZVS of Sbot within dead time (boost operation).

Fig. 16. Experimental configuration of ZVS BDC.

Fig. 17. Experimental results during buck operation.

Fig. 18. Experimental results during boost operation.

Fig. 19. Dynamic response during buck operation

Fig. 20. Dynamic response during boost operation.

Fig. 21. Loss breakdown chart.

Fig. 22. Experimental efficiency graph

TABLE I PARAMETERS FOR THE SIMULATION

TABLE II LOSS BREAKDOWN OF ZVS METHOD

TABLE III EFFICIENCY COMPARISON OF ZVS METHOD

#### Acknowledgement

Supported by : National Research Foundation of Korea (NRF)

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