Current Self-Balanced Bidirectional DC-DC Converter with Low Current Ripple and High Voltage Gain

doi:10.12141/j.issn.1000-565X.220265

Abstract

Abstract:

As a key interface device of the energy storage module in the integrated energy system, the bidirectional DC converter needs the features of low current ripple, high voltage gain and wide range soft switching. To achieve battery-friendly low current ripple ability, bidirectional DC converters use interleaving technology on the low-voltage energy storage side. However, restricted by the actual production process, this type of interleaved bidirectional DC converter has multi-phase current imbalance problems. In this paper, a current self-balancing bidirectional DC converter without complex control algorithm was proposed based on coupled inductors. In the integrated energy storage scenario, the converter not only has the characteristics of current self-balancing, but also has the comprehensive advantages of low current ripple, high voltage gain and wide-range soft switching. First of all, the converter used the clamp capacitor ampere-second balance to forcefully maintain the interleaved current balance in one switching cycle. Hence the low current ripple characteristic of current self-balance was realized at the circuit topology level. Secondly, the coupled inductor is both an energy storage inductor and a transformer. Through the cooperation of the multi-stage gain structure of the circuit, the high voltage gain characteristic was realized. Finally, the converter used a voltage matching control and phase shifting control strategy to decouple the voltage gain and power direction and consequently soft switching characteristics were guaranteed under different working conditions. The article analyzed the working principle and circuit characteristics of the converter, and designed an experimental prototype with an operating voltage of 30 V to 40 V on the low-voltage side, 400 V on the high-voltage side, and a bidirectional power of 1 kW. The experimental prototype simulated the operating characteristics of the low-voltage side lithium battery under different operating voltages, power levels and directions, thus effectively verifying the feasibility of the topology.

Key words: bidirectional DC-DC converter, coupled-inductor, current self-balancing, soft-switching

CLC Number:

TM46

WANG Keying, HUANG Yi, WANG Zihao, et al. Current Self-Balanced Bidirectional DC-DC Converter with Low Current Ripple and High Voltage Gain[J]. Journal of South China University of Technology(Natural Science Edition), 2023, 51(6): 78-88.

Figures/Tables 14

Fig.1

Fig.2

Fig.3

Table 1

Transmission power expression"

模式	状态	φ取值范围	输出功率
升压	轻载	$0, D - 0.5$	$φ T V C_H 3 2 L k (2 - 2 D - φ)$
升压	额定	$D - 0.5,1 - D$	$T V C_H 3 2 L k (D - D 2 + φ - 2 φ 2 - 14)$
降压	轻载	$0.5 - D, 0$	$φ T V C_H 3 2 L k (2 - 2 D + φ)$
降压	额定	$D - 1,0.5 - D$	$T V C_H 3 2 L k (- D + D 2 + φ + 2 φ 2 + 14)$

Table 1

Fig.4

Fig.5

Fig.6

Table 2

Comparison between the proposed converter and the existing BDCs"

方法	开关数量	电容数量	磁芯数量	电压增益	纹波电流/A	电感感值/μH	电流均衡	软开关	开关数量
本文BDC	8	5	2	$2 n 1 - D$	3.27	50	自均衡	全范围	8
文献［8］	4	4	1	$2 1 - D$	3.22	335		有限范围	4
文献［13］	8	4	3	$2 n 1 - D$	12.60	13	不均衡	全范围	8
文献［17］	8	2	4	$1 1 - D$	4.55	220	算法均衡	硬开关	8

Table 2

Fig.7

Table 3

Fig.8

Fig.9

Fig.10

Fig.11

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参数	数值
高压侧电压V_H/V	400
低压侧电压V_L/V	30~40
开关频率f_s/kHz	50
额定功率P_R/kW	1
励磁电感L_m1 & L_m2/μH	50
漏感L_k/μH	41.3
低压侧钳位电容C_L1 & C_L2/μF	20
高压侧钳位电容C_H1-C_H3/μF	20
耦合电感匝比n	2
低压侧开关管S₁-S₄	IRFP4768
高压侧开关管Q₁-Q₄	IRFP360
钳位二极管D₁ & D₂	SDUR3040W

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