Overview and Comparison of Modulation and Control Strategies for Non-Resonant Single-Phase Dual-Active-Bridge dc-dc Converter

ABSTRACT:

The non-resonant single-phase dual-active-bridge (NSDAB) dc-dc converter has been increasingly adopted for isolated dc-dc power conversion systems. Over the past few years, significant research has been carried out to address the technical challenges associated with modulations and controls of NSDAB dc-dc converter. The aim of this paper is to review and compare these recent state-of-the-art modulation and control strategies. Firstly, the modulation strategies for NSDAB dc-dc converter are analyzed. All possible phase-shift patterns are demonstrated, and the correlation analysis of the typical phases-shift modulation methods for NSDAB dc-dc converter is presented. Then, an overview of steady-state efficiency optimization strategies is discussed for NSDAB dc-dc converter. Moreover, a review of optimized techniques for dynamic responses is also provided. For both the efficiency and dynamic optimizations, thorough comparisons and recommendations are provided in this paper. Finally, to improve both steady state and transient performances, a combination approach to optimize both efficiency and dynamics for NSDAB dc-dc converter based on the reviewed methods is presented in this paper.

KEYWORDS:

  1. DAB converter
  2. Power Losses
  3. Current Stress
  4. Reactive Power
  5. Efficiency
  6. Power Control
  7. Current Feedback Control
  8. Observer-Based Control
  9. Dynamic Performances

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

NSDAB dc-dc converter has become one of the most attractive isolated dc-dc power conversion topologies for DC grid, solid-state transformer, automotive application, energy storage system and aerospace application. This paper offers a comprehensive overview of modulation methods, efficiency-optimization schemes and dynamic-optimization strategies of NSDAB dc-dc converter, and thorough comparisons of different optimization methods are conducted:

1). The typical modulation methods including the advanced phase-shift modulation and the variable frequency modulation methods are presented in this paper. Based on all possible eighteen phase-shift modulation patterns, the reason why SPS, DPS, EPS and TPS modulation schemes are selected for NSDAB dc-dc converter is analyzed. Moreover, the correlation analysis of typical phase-shift modulation methods including SPS, DSP, EPS and TPS modulation methods is illustrated, which can explain why the TPS modulation method can always provide the best efficiency for NSDAB dc-dc converter.

2). An overview of efficiency optimization schemes for NSDAB dc-dc converter including power-loss-model-based optimization methods, nonactive power optimization techniques, inductance current optimization strategies, ZVS range optimization schemes and burst mode are conducted. Under the consideration of both optimized performance and feasibility, the minimum-current-stress-optimized strategy with simple operation is recommended.

3). The paper also provides an overview of dynamic optimization strategies for NSDAB dc-dc converter including load-current feedforward schemes, direct-inductance-current control strategies and power-based control methods. When NSDAB dc-dc converter is connected to resistive load, the virtual-direct-power control scheme and the current sensorless control strategy are recommended because of excellent dynamic responses. When NSDAB dc-dc converter is connected to dc voltage bus, the asymmetric double-side modulation and the predictive current-mode control for fast transient response of required inductance current are recommended.

4). Finally, the paper presents an idea of hybrid efficiency-and dynamic-optimization concept to improve both steady state and transient performances of NSDAB dc-dc converter. A static and dynamic optimization strategy by combining minimum-current-stress strategy and power-control concept verifies the feasibility of the presented idea.

REFERENCES:

[1]R. W. De Doncker, D. M. Divan and M. H. Kheraluwala, “A three-phase soft-switched high power density DC/DC converter for high power applications,”Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting, Pittsburgh, PA, USA, 1988, pp. 796-805 vol.1.

[2]R. W. A. A. De Doncker, D. M. Divan and M. H. Kheraluwala, “A three-phase soft-switched high-power-density DC/DC converter for high-power applications,” inIEEE Transactions on Industry Applications, vol. 27, no. 1, pp. 63-73, Jan.-Feb. 1991.

[3]H. Akagi, S. Kinouchi and Y. Miyazaki, “Bidirectional isolated dual-active-bridge (DAB) DC-DC converters using 1.2-kV 400-A SiC-MOSFET dual modules,” inCPSS Transactions on Power Electronics and Applications, vol. 1, no. 1, pp. 33-40, Dec. 2016.

[4]B. Zhao, Q. Song, W. Liu and Y. Xiao, “Next-Generation Multi-Functional Modular Intelligent UPS Systemfor Smart Grid,” inIEEE Transactions on Industrial Electronics, vol. 60, no. 9, pp. 3602-3618, Sept. 2013.

[5]H. Wen, W. Xiao and B. Su, “Nonactive Power Loss Minimization in a Bidirectional Isolated DC-DC Converter for Distributed Power Systems,” inIEEE Transactions on Industrial Electronics, vol. 61, no. 12, pp. 6822-6831, Dec. 2014.

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