基于多输入绕组变压器的动力电池双层主动均衡电路研究
发布时间：2018-12-18 14:30
【摘要】：新能源汽车的快速推广带动了动力电池产业的迅猛发展,推动了相关产品开发和前沿课题研究。其中,针对车载离子动力电池及其管理系统的研究是目前各新能源车企、高校及科研机构的研究热点,仍有诸多技术难题有待攻关。车载锂离子电池组由成百上千节单体电池串并联组成,以满足整车驱动功率和续航里程的需求。由于单体电池之间的出厂自身参数不尽相同,以及后期使用环境、工况条件、自放电率等因素的差异影响,极易导致电池单体间的内阻、电压、容量等内外参数的不一致性,并随着电池组循环次数的增加和逐步老化而累积加重,从而严重影响整个电池组的可用容量和使用性能,降低整车安全系数。为解决电池组内部各单体间、各模块间的不一致性问题,提升电池组的寿命周期和性能,延长整车的续航里程,保证整车运行安全,本文针对车载锂离子动力电池均衡系统及其控制策略展开研究。主要工作包括:(1)分析了锂离子电池不一致性产生的成因及表现,明确了后期使用环境、工况条件等因素造成的不一致性可以通过能量均衡方式来改善。(2)对比分析了针对锂离子电池的多种均衡电路拓扑方案,设计了一种双层主动均衡电路拓扑,底层电路设计考虑模块内布局空间及散热条件有限问题,选用基于升降压变换的主动均衡拓扑,具有体积小、易于模块化及效率高的特点;顶层电路设计考虑模块间均衡功率大及模块数量多问题,提出一种基于多输入绕组变压器的主动均衡拓扑,具有均衡速度快、均衡控制方式灵活以及易于级联扩展的特点。(3)建立了基于Simulink仿真平台的均衡系统模型,验证了所设计的双层主动均衡电路拓扑的有效性,继而搭建设计了均衡实验硬件平台,包括主控单元、电池组信息采集单元、均衡单元等。(4)设计了基于压差和单体电压等级的变占空比控制,实现了对均衡电流的动态调节,有效避免了单体电压波动导致的瞬间过充过放现象,缩短了均衡时间。针对均衡结束后电压恢复导致的压差回升现象,提出了基于电池极化电压的过均衡控制,提升了一致性均衡效果。同时基于明显老化电池均衡容易产生的误均衡问题,提出了基于历史充电信息和单体电压上升率的末期均衡策略,有效避免了误均衡现象。(5)针对所提出的均衡拓扑电路进行实验验证,分别设计并开展了静置状态下和恒流充电工况下的均衡实验;在恒流充电工况下,分别在慢充0.25C和快充0.50C下验证了均衡电路的适用性。实验结果表明本文设计的车载锂离子动力电池双层主动均衡系统具有很好的均衡效果,有效改善了电池组内电压的不一致现象,提升了可用容量。
[Abstract]:The rapid promotion of new energy vehicles drives the rapid development of power battery industry, and promotes the development of related products and frontier research. Among them, the research on the on-board ion power battery and its management system is the research hotspot of the new energy vehicle enterprises, universities and scientific research institutions at present, and there are still many technical problems to be solved. The lithium-ion battery pack is composed of hundreds of single batteries in series and parallel to meet the requirements of driving power and mileage. Because of the different parameters of the cell, the difference of the environment, the working condition and the rate of self-discharge, it is easy to cause the inconsistency of the internal resistance, voltage, capacity and other internal and external parameters of the cell, such as internal resistance, voltage, capacity and so on. With the increase of cycle times and gradual aging of the battery pack, the accumulative aggravation will seriously affect the available capacity and service performance of the whole battery pack and reduce the safety factor of the whole vehicle. In order to solve the problem of inconsistency between each cell and module in the battery pack, improve the life cycle and performance of the battery pack, prolong the range of the whole vehicle, and ensure the safety of the whole vehicle, In this paper, the equalization system and control strategy of vehicle-mounted lithium-ion battery are studied. The main works are as follows: (1) the causes and manifestations of the inconsistency of lithium ion batteries are analyzed, and the later use environment is defined. The inconsistency caused by operating conditions and other factors can be improved by energy equalization. (2) the topology schemes of various equalization circuits for lithium-ion batteries are compared and a double-layer active equalization circuit topology is designed. The bottom circuit design takes into account the limited layout space and heat dissipation condition in the module, and chooses the active balanced topology based on the lifting voltage transformation, which has the characteristics of small volume, easy modularization and high efficiency. The top-level circuit design takes into account the problems of large equalization power between modules and the number of modules, and proposes an active equalization topology based on multi-input windings transformer, which has high equalization speed. The equalization control mode is flexible and easy to cascade expansion. (3) the equalization system model based on Simulink simulation platform is established to verify the effectiveness of the designed two-layer active equalization circuit topology. Then the hardware platform of the equalization experiment is built, including the main control unit, the battery pack information collection unit, the equalization unit and so on. (4) the variable duty cycle control based on the pressure difference and the cell voltage level is designed. The dynamic regulation of the equalization current is realized, which effectively avoids the transient overcharging caused by the voltage fluctuation of the single unit and shortens the equalization time. Aiming at the recovery of voltage difference caused by voltage recovery after equalization, an over-equalization control based on battery polarization voltage is proposed to improve the consistency equalization effect. Based on the problem of error-equalization caused by obvious aging battery equalization, this paper puts forward a end-stage equalization strategy based on historical charging information and cell voltage rise rate. Effectively avoid the phenomenon of misequalization. (5) the proposed equalization topology circuit is verified experimentally, and the equalization experiments under static state and constant current charging condition are designed and carried out respectively. Under constant current charging condition, the applicability of equalization circuit is verified at slow charging 0.25C and fast charging 0.50C respectively. The experimental results show that the two-layer active equalization system designed in this paper has a good equalization effect, effectively improves the inconsistency of the voltage in the battery pack and increases the available capacity.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912
本文编号：2385982
[Abstract]:The rapid promotion of new energy vehicles drives the rapid development of power battery industry, and promotes the development of related products and frontier research. Among them, the research on the on-board ion power battery and its management system is the research hotspot of the new energy vehicle enterprises, universities and scientific research institutions at present, and there are still many technical problems to be solved. The lithium-ion battery pack is composed of hundreds of single batteries in series and parallel to meet the requirements of driving power and mileage. Because of the different parameters of the cell, the difference of the environment, the working condition and the rate of self-discharge, it is easy to cause the inconsistency of the internal resistance, voltage, capacity and other internal and external parameters of the cell, such as internal resistance, voltage, capacity and so on. With the increase of cycle times and gradual aging of the battery pack, the accumulative aggravation will seriously affect the available capacity and service performance of the whole battery pack and reduce the safety factor of the whole vehicle. In order to solve the problem of inconsistency between each cell and module in the battery pack, improve the life cycle and performance of the battery pack, prolong the range of the whole vehicle, and ensure the safety of the whole vehicle, In this paper, the equalization system and control strategy of vehicle-mounted lithium-ion battery are studied. The main works are as follows: (1) the causes and manifestations of the inconsistency of lithium ion batteries are analyzed, and the later use environment is defined. The inconsistency caused by operating conditions and other factors can be improved by energy equalization. (2) the topology schemes of various equalization circuits for lithium-ion batteries are compared and a double-layer active equalization circuit topology is designed. The bottom circuit design takes into account the limited layout space and heat dissipation condition in the module, and chooses the active balanced topology based on the lifting voltage transformation, which has the characteristics of small volume, easy modularization and high efficiency. The top-level circuit design takes into account the problems of large equalization power between modules and the number of modules, and proposes an active equalization topology based on multi-input windings transformer, which has high equalization speed. The equalization control mode is flexible and easy to cascade expansion. (3) the equalization system model based on Simulink simulation platform is established to verify the effectiveness of the designed two-layer active equalization circuit topology. Then the hardware platform of the equalization experiment is built, including the main control unit, the battery pack information collection unit, the equalization unit and so on. (4) the variable duty cycle control based on the pressure difference and the cell voltage level is designed. The dynamic regulation of the equalization current is realized, which effectively avoids the transient overcharging caused by the voltage fluctuation of the single unit and shortens the equalization time. Aiming at the recovery of voltage difference caused by voltage recovery after equalization, an over-equalization control based on battery polarization voltage is proposed to improve the consistency equalization effect. Based on the problem of error-equalization caused by obvious aging battery equalization, this paper puts forward a end-stage equalization strategy based on historical charging information and cell voltage rise rate. Effectively avoid the phenomenon of misequalization. (5) the proposed equalization topology circuit is verified experimentally, and the equalization experiments under static state and constant current charging condition are designed and carried out respectively. Under constant current charging condition, the applicability of equalization circuit is verified at slow charging 0.25C and fast charging 0.50C respectively. The experimental results show that the two-layer active equalization system designed in this paper has a good equalization effect, effectively improves the inconsistency of the voltage in the battery pack and increases the available capacity.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912
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