Studies on the influence of manufacturing processes on the eddy current losses of single-tooth stator lamination stacks for use in hybrid and electric drives

由于社会和政治对环保和可持续汽车技术的需求，该行业正面临开发新动力系统概念的要求。许多动力系统概念都是基于电动马达驱动系统。这可以是一辆配备大电池的全电动汽车，一辆混合动力汽车或一辆燃料电池汽车。所有的概念车都有一个共同的主要动力系统部件——电动机。减少电动机的功率损耗是开发活动的主要焦点之一。功率损耗直接影响到CO2排放法规的符合性、电动汽车的行驶里程、电池的成本和重量以及系统的冷却功率需求。因此，必须从根本上调查所有类型的功率损耗，必须确定减少功率损耗的潜力，必须建立和实施改进措施。一种损耗是涡流损耗。涡流损耗主要产生在电动机铁芯的片层中。为了使涡流损耗最小化，堆叠的各个层都是电绝缘的。然而，制造工艺的应用可能导致层压的电气连接，最初是绝缘的堆栈，因此将导致额外的涡流损失。制造过程对额外涡流损耗的影响目前还不清楚。电动机的一个主要部件是层压定子铁芯。制造工艺步骤，切割单个层压片，将层压片堆叠到铁芯以及在外壳中组装定子铁芯的不同之处在于它们的涡流损耗影响。因此，所提出的研究项目的主要目标是确定通过各种制造过程的影响而产生的涡流损失。为此，必须确定由制造过程引起的涡流路径，并检测相关的几何和电气尺寸。下一步必须进行有限元模拟，并根据所发现的涡流特性建立解析计算模型。最后，对仿真和计算结果进行了实测验证。根据已确定的涡流特性，可以规定应用工艺和零件质量的损耗最小化要求。此外，还可以为定子铁芯的设计提供一条以降低损耗为重点的指导方针。此外，调查结果将成为确定其他减少损耗的制造工艺的基础，例如在某些位置插入绝缘层以断开涡流路径。在最后一步中，必须通过测量来评价已确定的减少损失行动的有效性。

Due to societal and political demand for environmental-friendly and sustainable automotive technology, the industry is facing requests to develop new powertrain concepts. Many of the powertrain concepts are based on a drive system with electric motors. This can be a full electric vehicle with a large battery, a hybrid vehicle or a fuel cell vehicle. All concepts do have, as a common main powertrain component, an electric motor. The reduction of the power loss of the electric motor is one major focus of the development activities. The power loss has straight impact to the compliance with the CO2 emission regulations, the operating range of the electric vehicle, the cost and weight of the battery and the cooling power demand of the system. For this reason the entire types of power losses have to be investigated fundamentally, power loss reduction potentials have to be identified and improvements have to be established and implemented.One type of losses is the eddy current losses. The eddy current losses are mainly generated in the laminations of the iron cores of the electric motor. For eddy current loss minimisation the individual laminations of the stack are electrically insulated. However the application of manufacturing processes can lead to electrical connections of the laminated, initially insulated stack and will therefore lead to additional eddy current losses. The impact of the manufacturing processes concerning additional eddy current losses is currently not sufficiently known.A major component of the electric motor is the laminated stator core. The manufacturing process steps, cutting of the individual lamination, stacking of the laminations to a core and the assembly of the stator core in a housing differ concerning their eddy current loss impact. The main target of the presented research project is therefore the determination of the eddy current losses created through the impact of various manufacturing processes. For this purpose, the eddy current paths caused by the manufacturing processes have to be identified and the relevant geometrical and electrical dimensions have to be detected. In a next step FEM simulations have to be carried out and based on the found eddy current characteristics analytical calculation models can be developed. Finally, the simulation and calculation results have to be validated by measurements.Based on the identified eddy current characteristics requirements for loss minimisation of the applied processes and the part quality can be specified. In addition a guide line for the design of stator cores with the focus on loss reduction can be offered. Further the results of the investigations will be the basis for the determination of additional manufacturing processes for loss reduction e.g. the insertion of insulation layers at certain locations to disconnect eddy current paths. In a last step the identified loss reduction actions have to be evaluated concerning their effectiveness by measurements.