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境友好和可持续发展的汽车技术的需求，该行业面临着开发新的动力总成概念的要求。动力总成的许多概念都是基于电动马达的驱动系统。这可以是一辆配备大电池的全电动汽车，也可以是一辆混合动力汽车或燃料电池汽车。所有概念车都有电动马达，作为共同的主动力总成部件。降低电机的功率损耗是开发活动的一大重点。功率损耗直接影响到电动汽车对二氧化碳排放法规的遵守、电动汽车的续航里程、电池的成本和重量以及系统的冷却功率需求。为此，必须从根本上调查所有类型的功率损耗，必须确定功率损耗降低的潜力，并建立和实施改进措施。涡流损耗是一种类型的损耗。涡流损耗主要产生在电机铁芯的叠片中。为了将涡流损耗降至最低，电堆的各个叠片都是电绝缘的。然而，制造工艺的应用可能导致叠层的、最初绝缘的电堆的电连接，因此将导致额外的涡流损耗。制造工艺对额外涡流损耗的影响目前还不是很清楚。电机的一个主要部件是叠片定子铁心。制造工艺步骤、单个叠片的切割、叠层到铁心以及定子铁心在外壳中的组装在其涡流损耗影响方面有所不同。因此，本研究项目的主要目标是确定由于各种制造工艺的影响而产生的涡流损耗。为此，必须识别由制造工艺引起的涡流路径，并且必须检测相关的几何尺寸和电气尺寸。在下一步中，必须进行有限元模拟，并基于所发现的涡流特性建立分析计算模型。最后，模拟和计算结果必须通过测量来验证。根据识别的涡流特性，可以指定应用工艺的损耗最小化的要求和零件的质量。此外，还可以为定子铁心的设计提供一个以降低损耗为重点的指导方针。此外，调查结果将作为确定降低损耗的其他制造工艺的基础，例如在某些位置插入绝缘层以切断涡流路径。在最后一步，必须通过测量对已确定的减少损失行动的有效性进行评估。

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.