应用于纯电动汽车的磁耦合式级联型混合驱动系统研究

A magnet-coupled cascaded converter is proposed to solve the existing problems in electric-vehicle applications. The problems can be described as: (1) The battery voltage is relatively low compared with the rating voltage of the AC motor; (2) Large-current charging/discharging for the batteries are not allowed hence the regenerative energy can't be saved completely and the acceleration ability of the vehicle is limited. In this research, three major topics are discussed: (1) An equalizer based on a multi-winding high-frequency transformer is proposed to balance the battery-cell voltages in the string. The equalizer has some merits such as high efficiency and high equalization speed. The equalizer can make the string work normally even when some of the cells deteriorate. Thus the reliability can be improved. (2) A multi-level converter is proposed which is the combination of some magnet-coupled modules and a traditional inverter. With the help of the topology, higher AC voltages can be obtained, which makes it possible to drive the large-capacity high-voltage AC motors on the vehicle and improve the performance. (3) The super capacitors are introduced to absorb and release short-term large power, which can improve the acceleration ability and make it possible to collect the regenerative energy. The proposed topology can regulate the energy stored in the batteries and super capacitors. The analysis about how to manage the energy is carried out, which can improve the performance of the vehicle. In the research, a 30kW prototype will be invented and it will be installed on an electric vehicle to test the performance and validate the analysis. The proposed system can also be used in other applications such as power systems and micro grids.

为了解决纯电动汽车领域车载电池电压较低而中大功率动力电机额定电压较高的矛盾，提高车辆电机驱动系统的启停运行性能，课题提出一种磁耦合式级联型混合驱动系统，并从三个方面进行研究：1.利用多绕组高频变压器和H桥单元构成均压电路，实现串联的蓄电池单体间的能量交换，具有均压效率高、均压速度快的特点。在部分单体故障和失效情况下，实现系统的正常运行，有利于提高系统可靠性；2.利用磁耦合技术和多电平技术，提升输出电压等级，实现用低压电池组驱动较高电压电机，满足车辆对加速性能和续航里程等指标的要求；3.课题研究的混合驱动系统将蓄电池和超级电容进行了结合，并对其能量进行管理，有利于发挥不同储能介质在充放电速度和能量密度等方面的优势。课题在完成理论分析和实验验证的基础上，拟完成一套30kW驱动系统样机并改装一辆纯电动汽车，用于研究该方案的工业化应用问题。课题方案还可用于电力系统储能和微电网等领域，实用性较好。

在纯电动汽车领域，需要使用蓄电池为车辆提供能量。为了适配车辆中的动力电机，一般需要提高蓄电池的额定电压为400V甚至更高，这需要将更多的蓄电池单体进行串联。大量的蓄电池单体串联后，降低了系统的可靠性，并增加了蓄电池管理系统的成本。为此，本项目提出了一种磁耦合式级联型混合驱动系统，该系统可以使用低压电池驱动较高电压的电机，提高车载蓄电池的可靠性，降低系统成本，提升车辆电机驱动系统的加减速运行性能，满足纯电动汽车对驱动系统的要求。本项目重点研究了3个方面的内容：1.研究了基于多绕组高频变压器和H桥单元构成的均压电路的工作原理、建模方法和关键技术；2.利用磁耦合技术和多电平技术，实现低压电池供电情况下的高压输出，驱动电机正常运行；3.研究蓄电池和超级电容的能量管理技术，发挥超级电容充放电速度快的优势。经过研究，主要取得了如下成果：1.建立了基于多绕组高频变压器和H桥单元构成的均压电路的数学模型，分析了其运行原理特性，并完成了仿真模型和实验验证，形成了实用化的均压电路设计方案；2.完成了磁耦合技术和多电平技术的理论分析，形成了系统的调制策略和控制算法，实现了级联输出高电压，完成了实验样机，实现了对电机的高性能控制；3.分析了超级电容的充放电模型，形成了利用超级电容吞吐能量的算法。本项目的研究成果验证了技术方案的正确性和可行性，研制的实验样机实现了预期功能。基于本项目提出的拓扑结构和控制算法，可以使用额定电压为108V的蓄电池驱动额定电压为220V的交流电机，并完成电机的正反转运行和频繁启制动，显著降低了蓄电池均压系统的复杂度和成本，为纯电动汽车电驱系统提供了新的解决方案。