Integrated Drive System with Modularised Energy Storage for Automotive Applications

汽车电气化是工业的重大转变，带来了丰富的机会。电动汽车动力系统的标准拓扑结构是基于一个由大型单个电池组供电的两电平逆变器。单独的车载充电器，DC-DC转换器和电池管理系统需要完成电力电子包。虽然电力电子设备与电机的集成正在积极研究中，但它也可以在电池组内的一个可能不那么恶劣的环境中与电机分离。模块化多电平转换器不仅可以实现模块化电池组和电力电子设计，还可以将逆变器和车载充电器集成到电池组本身。在可预见的未来，成本和效率仍然是汽车制造商面临的最大挑战，这项研究有可能提供一套不同的设计限制，这可能有利于某些应用。目的和目标是文献综述：1)理解,记录并量化汽车动力系统应用中对此类系统的要求和约束2)理解并量化特定拓扑结构给动力系统成本和效率带来的好处和缺点观察行为：1)模拟TLI和MMC拓扑（各种子模块设计和级别）的行为（电气和热）以复制文献综述中的观察结果2)开发辅助模型以协助模拟行为3)确定各种用例的最佳拓扑，并确定它们彼此之间的关系创建理论以匹配状态并预测其他状态下的系统行为：1)从上面选择一个有前途的候选拓扑，并使用模拟来预测新用例下的操作2)将其与预测的不良性能进行比较（避免误报）3)将其与预测的不适合用例进行比较（避免误报）测试系统在其他状态下并验证预测：1)对两个候选拓扑进行原型设计，并验证它们满足要求集（优先考虑第一个候选拓扑）2)使用原型驱动器和负载在HiL钻机上验证仿真结果目的是研究在模块化多电平转换器拓扑中使用低成本低压GaN器件，以确定其在汽车动力系统应用中的可行性。重点将放在高电压、高功率、重型动力系统上。该设计已经用于高压直流输电线路，并且一些汽车供应商已经提供基本的3电平转换器，该设计寻求使用串联的低压开关，以获得高压操作能力。研究表明，这些拓扑结构的更复杂版本能够同时承担逆变器和车载充电器的职责，同时成为电池组的组成部分。研究在TRL3进行，在那里进行分析和实验关键功能和/或特性概念验证工作。这是EPSRC定义的资助TRL职权范围的上限。该研究的主题是符合AAPS CDT宗旨的车辆电气化，该概念有可能降低车辆组件成本，更好地管理电池充电状态和热包线，并通过进一步将电子设备和电池集成到模块化系统中，从而有利于设计

Vehicle electrification is a major shift in industry bringing a wealth of opportunities. Standard topology EV Powertrains are based on a two level inverter fed by a large single battery pack. Separate onboard charger, DC-DC converter and battery management systems are needed to complete the Power Electronics package. While integration of power electronics with the motor is under active research, it can also be integrated away from the motor in a potentially less harsh environment within the battery pack. Modular Multilevel Converters have the potential not only to allow for modular battery pack and power electronics design but also integration of the Inverter and Onboard Charger within the battery pack itself. As cost and efficiency continue to be the biggest challenges facing vehicle manufacturers today and for the foreseeable future, this research has the potential to offer a different set of design constraints which may benefit certain applications.The aims and objectives areLiterature review: 1) Understand, document and quantify the requirements and constraints placed upon systems like this in an automotive powertrain application2) Understand and quantify the benefits and drawbacks brought to powertrain costs and efficiency by the particular topologyObserve Behaviour:1) Simulate behaviour (Electrical and Thermal) of TLI and MMC topologies (Various submodule designs and number of levels) to replicate observations in Literature review2) Develop auxiliary models to assist in simulating behaviour of topologies over a number of industry standard drive cycles3) Determine optimum topologies for various use-cases and ascertain how these relate to each otherCreate theory to match states and predict system behaviour in other state:1) Pick a promising candidate topology from the above and use simulation to predict operation under new use case2) Compare this against a predicted bad performer (Avoid false positives)3) Compare this against a predicted unsuited use case (Avoid false negatives)Test system in other state and validate predictions:1) Prototype the two candidate topologies and verify they meet the requirements set (Priority on first candidate)2) Validate the simulation results on HiL rig using prototype drives and loadsThe aim is to research the use of low cost low voltage GaN based devices in modular multilevel converter topologies to ascertain their viability in automotive powertrain applications. The main focus would be on high voltage high power heavy duty powertrains. Already used in HVDC power transmission lines, and with some automotive suppliers offering basic 3 level converters already, the design seeks to use low voltage switches in series, to gain High Voltage operating capability. Research has shown more complex versions of these topologies able to simultaneously take on duties of Inverter and on board charger while being an integral part of the battery pack.The research carried out is at TRL3 where analytical and experimental critical function and/or characteristic proof-of concept work is undertaken. This is at the upper end of the EPSRC's defined funding TRL remit. The theme of the research is vehicle electrification in line with the AAPS CDT remit and the concept potentially allows for lowering vehicle component costs, better managing the battery state of charge and thermal envelope, as well as benefiting design by further integrating electronics and battery into modular systems