{"id":16289,"date":"2020-06-29T04:24:44","date_gmt":"2020-06-29T08:24:44","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/simcenter\/?p=16289"},"modified":"2026-03-26T06:09:34","modified_gmt":"2026-03-26T10:09:34","slug":"facilitating-innovation-in-thermal-integration-of-evs-electric-machines","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/simcenter\/facilitating-innovation-in-thermal-integration-of-evs-electric-machines\/","title":{"rendered":"Thermal simulation of electric machines"},"content":{"rendered":"\n

Facilitating innovation in thermal integration of electric machines<\/h2>\n\n\n\n

Efficiency regulations for electrical machines are placing greater demands on electrical machine designers. Now, alongside an optimized electromagnetic design, the thermal simulation of electric machines has also become increasingly important in the design process. Especially as the different industries are focusing more and more on higher torque, higher power density and increased efficiency demand, along with reduction in size, weight and cost. Finally, more performance and a smaller package is resulting in higher operating temperatures with higher temperature gradients. Therefore, new generation of electric machines requires in general higher performance material, typically higher insulation class material and higher performance magnets. Those technical requirements are calling for alternative methodologies during engineering process to balance all those constraints (innovation, costs and delays). Again, digitalization is key.<\/p>\n\n\n\n

Simulation can be a precious ally to help in addressing those complex challenges at various stages of the design process.<\/p>\n\n\n\n

Our complete Simcenter electric machine thermal simulation is presented in the following on-demand webinar<\/a>. The traction e-machine design V-Cycle is described, including:<\/p>\n\n\n\n

  1. System simulation at the requirements for the cooling strategy<\/li>
  2. Empirical-based thermal analysis of the cooling system of the machine for a rapid turnaround of some cooling concepts<\/li>
  3. CFD-based multi-physics analysis to study on a 3D detailed geometry the design of the machine cooling system and its optimization for overall machine performance improvement<\/li>
  4. Full powertrain system simulation and validation of the design on transient drive cycles<\/li><\/ol>\n\n\n\n
    \"Thermal<\/figure>\n\n\n\n

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    In this blog, we will focus on the validation the cooling requirements of a traction motor in realistic vehicle conditions and transient drive cycles<\/p>\n\n\n\n

    Model requirement<\/strong><\/h3>\n\n\n\n

    Once the internal cooling of the machine has been designed, the next challenge is to validate the cooling system design and control, to improve motor performance, efficiency and durability.<\/p>\n\n\n\n

    To do so, we will use:<\/p>\n\n\n\n

    1. First, a reduced model to simulate the machine electromagnetic performance accounting for the magnetic non-linearities, the permanent magnet temperature, the losses in the rotor, yoke and tooth sectors and the winding temperature. Usually, information of losses comes from a detailed electromagnetic simulation done with Simcenter SPEED, Simcenter Motorsolve or Simcenter MAGNET.<\/li>
    2. Second, a lumped thermal model of the permanent magnet synchronous motor (PMSM) with thermal capacitances and resistances calculated from geometry. I will give more details later<\/li><\/ol>\n\n\n\n

      Again, the objective is to simulate the e-motor in realistic driving conditions, and check that the temperature of the main parts of the motor such as the windings or the magnet remains under a given limit.<\/p>\n\n\n\n

      Geometry based electric machine thermal model<\/strong><\/h3>\n\n\n\n

      The first step is to obtain a complete model of an electric machine considering thermal and electric phenomena. Let’s take as an example the Nissan Leaf machine, 2012 version. Rotor and stator parts are modeled taking into account radial and circumferential heat transfer between the different elements of the machine. Thermal heat exchanges with the shaft are neglected.<\/p>\n\n\n\n

      18 thermal nodes are used to model the Nissan Leaf electric motor. The thermal modeling approach is presented in the drawing in the middle. Each thermal node is exchanging heat with others through thermal resistance. Rotor and stator parts are modeled using thermal capacitances, and radial and circumferential heat transfer between the different elements of the machine are represented by thermal resistance. These thermal capacitance and resistance are computed using analytical expressions, starting from the information on the machine geometry and material properties. <\/p>\n\n\n\n