|
|
Transient DC Bias Suppression Strategy of Dual Active Bridge Based on Direct Power Control |
Liu Ziwei, Sun Zhaolong, Liu Baolong, Zheng Wei |
School of Electrical Engineering Naval University of Engineering Wuhan 430033 China |
|
|
Abstract The dual active bridge (DAB) has the advantages of bidirectional energy flow, low voltage and current stress of switching devices, input-output galvanic isolation, high power density, and soft switching. Thus, it is widely used in electric vehicles, DC distribution networks, microgrids, distributed energy, and other fields. When the input voltage changes or the load changes suddenly, the DAB converter will generate a transient DC bias current on the primary side of the transformer, leading to problems such as excessive primary current peak value and saturation of the transformer core. The improved triple phase shift (ITPS) control strategy based on direct power control is proposed to eliminate the DAB transient DC bias current. Firstly, the RMS optimization strategy based on multiple harmonic minimizations is reviewed, and the direct power control model of DAB under this strategy is deduced. Secondly, the transient DC bias current of different cases is analyzed, and the phase shift ratio combination scheme for suppressing the transient DC bias current is determined. When the DAB operation mode is changed, the duty cycle of the MOSFET in the transient period is adjusted to maintain the volt-second balance of the transformer. Then, when the DAB converter is used as a DC power supply, the transmission power and output voltage should be controlled. Since the relationship between the shift ratio and the transmission power is non-linear, the shift ratio cannot be directly determined by the voltage loop output. Therefore, combined with the power inner loop, the control method of the voltage outer loop based on the PI strategy is determined to realize the dual-loop control. Finally, a DAB converter prototype is built to verify the effectiveness of the proposed strategy. The experimental results show that when the transmission power steps within the heavy load range, the ITPS strategy shortens the transition time from six cycles to one cycle and reduces the peak value of transient current from 16 A to 11.5 A. When the transmission power steps from light load to heavy load, the ITPS strategy shortens the transition time from six cycles to one cycle and reduces the peak value of transient current from 19.7 A to 13.2 A. When the transmission power steps from heavy load to light load, there will be no current spike in the transient process, and the ITPS strategy shortens the transition time from four cycles to one cycle. In addition, compared with the SPS and FDM strategies, the ITPS strategy can reduce the RMS current by 18.5 % and effectively improves efficiency. The following conclusions can be drawn from the simulation and experimental results: (1) Compared with the traditional modulation strategy, the ITPS strategy can effectively suppress the transient bias current and shorten the transient process. (2) The ITPS strategy combines the dynamic performance of DAB with the optimization of steady-state performance, which can achieve a fast transient response while ensuring the optimization of the current RMS.
|
Received: 23 May 2022
|
|
|
|
|
[1] Zhao Biao, Song Qiang, Liu Wenhua, et al.Overview of dual-active-bridge isolated bidirectional DC-DC converter for high-frequency-link power-conversion system[J]. IEEE Transactions on Power Electronics, 2014, 29(8): 4091-4106. [2] 雷志方, 汪飞, 高艳霞, 等. 面向直流微网的双向DC-DC变换器研究现状和应用分析[J]. 电工技术学报, 2016, 31(22): 137-147. Lei Zhifang, Wang Fei, Gao Yanxia, et al.Research status and application analysis of bidirectional DC-DC converters in DC microgrids[J]. Transactions of China Electrotechnical Society, 2016, 31(22): 137-147. [3] 年珩, 叶余桦. 三端口隔离双向DC-DC变换器模型预测控制技术[J]. 电工技术学报, 2020, 35(16): 3478-3488. Nian Heng, Ye Yuhua.Model predictive control of three-port isolated bidirectional DC-DC converter[J]. Transactions of China Electrotechnical Society, 2020, 35(16): 3478-3488. [4] Esteban F D, Serra F M, De Angelo C H. Control of a DC-DC dual active bridge converter in DC microgrids applications[J]. Revista IEEE América Latina, 2021, 19(8): 1261-1269. [5] Yang Xuan, Xu Yang, Chen Wenjie, et al.A three-level dual-active-bridge converter with blocking capacitors for bidirectional electric vehicle charger[J]. IEEE Access, 2019, 7: 173838-173847. [6] Bai Hua, Nie Ziling, Mi Chunting.Experimental comparison of traditional phase-shift, dual-phase-shift, and model-based control of isolated bidirectional DC-DC converters[J]. IEEE Transactions on Power Electronics, 2010, 25(6): 1444-1449. [7] Everts J, Krismer F, Van den Keybus J, et al. Optimal ZVS modulation of single-phase single-stage bidi-rectional DAB AC-DC converters[J]. IEEE Transa-ctions on Power Electronics, 2014, 29(8): 3954-3970. [8] Bal S, Yelaverthi D B, Rathore A K, et al.Improved modulation strategy using dual phase shift modulation for active commutated current-fed dual active bridge[J]. IEEE Transactions on Power Electronics, 2018, 33(9): 7359-7375. [9] Wang Peng, Chen Xianzhong, Tong Chaonan, et al.Large and small signal average value modeling of dual-active-bridge DC-DC converter with triple-phase-shift control[J]. IEEE Transactions on Power Electronics, 2021, 36(8): 9237-9250. [10] 吴俊娟, 孟德越, 申彦峰, 等. 双重移相控制与传统移相控制相结合的双有源桥式DC-DC变换器优化控制策略[J]. 电工技术学报, 2016, 31(19): 97-105. Wu Junjuan, Meng Deyue, Shen Yanfeng, et al.Optimal control strategy of dual active bridge DC-DC converter with combined dual-phase-shift and traditional-phase-shift controls[J]. Transactions of China Electrotechnical Society, 2016, 31(19): 97-105. [11] 王仁龙, 杨庆新, 操孙鹏, 等. 一种优化电流应力的双有源桥式DC-DC变换器双重移相调制策略[J]. 电工技术学报, 2021, 36(增刊1): 274-282. Wang Renlong, Yang Qingxin, Cao Sunpeng, et al.An optimized dual phase shift modulation strategy for dual active bridge DC-DC converter[J]. Transactions of China Electrotechnical Society, 2021, 36(S1): 274-282. [12] Tong Anping, Hang Lijun, Li Guojie, et al.Modeling and analysis of a dual-active-bridge isolated bidirectional DC/DC converter to minimize RMS current with whole operating range[J]. IEEE Transactions on Power Electronics, 2018, 33(6): 5302-5316. [13] Choi W, Rho K, Cho B.Fundamental duty modulation of dual-active-bridge converter for wide range operation[J]. IEEE Transactions on Power Electronics, 2016, 31(6): 4048-4064. [14] Liu Tao, Xu Yang, Chen Wenjie, et al.Design and implementation of high-efficiency control scheme of dual active bridge based 10kV/1MW solid state transformer for PV application[J]. IEEE Transactions on Power Electronics, 2019, 34(5): 4223-4238. [15] Segaran D, Holmes D G, McGrath B P. Enhanced load step response for a bidirectional DC-DC con-verter[J]. IEEE Transactions on Power Electronics, 2013, 28(1): 371-379. [16] Song Wensheng, Nie Hou, Wu Mingyi.Virtual direct power. control scheme of dual active bridge DC-DC converters for fast dynamic response[J]. IEEE Transa-ctions on Power Electronics, 2018, 33(2): 1750-1759. [17] Dai Yong, Luo Suhua, Li Zhongwei.Direct power based control strategy for DAB DC-DC converter with cooperative triple phase shifted modulation[J]. IEEE Access, 2021, 9: 147791-147800. [18] Zhao Biao, Song Qiang, Liu Wenhua, et al.Transient DC bias and current impact effects of high-frequency-isolated bidirectional DC-DC converter in practice[J]. IEEE Transactions on Power Electronics, 2016, 31(4): 3203-3216. [19] 余雪萍, 涂春鸣, 肖凡, 等. 三端口隔离DC-DC变换器的暂态直流偏置机理及抑制策略[J]. 电工技术学报, 2020, 35(9): 1962-1972. Yu Xueping, Tu Chunming, Xiao Fan, et al.Transient DC bias mechanism and suppression strategy of the three-port isolated DC-DC converter[J]. Transactions of China Electrotechnical Society, 2020, 35(9): 1962-1972. [20] Dai Tianlin, Qin Jianggang, Ge Gao, et al.Research on transient DC bias analysis and suppression in EPS DAB DC-DC converter[J]. IEEE Access, 2020, 8(6): 1421-61432. [21] Bu Qinglei, Wen Huiqing, Wen Jiacheng, et al.Transient DC bias elimination of dual-active-bridge DC-DC converter with improved triple-phase-shift control[J]. IEEE Transactions on Industrial Elec-tronics, 2020, 67(10): 8587-8598. [22] Zhao Biao, Song Qiang, Liu Wenhua, et al.Dead-time effect of the high-frequency isolated bidirectional full-bridge DC-DC converter: comprehensive theo-retical analysis and experimental verification[J]. IEEE Transactions on Power Electronics, 2014, 29(4): 1667-1680. |
|
|
|