Thermal Performance of Motor and Inverter in an Integrated Starter Generator System for a Hybrid Electric Vehicle

Abstract

Abstract:If the integrated starter generator (ISG) motor and inverter operate under continuously high loading conditions, the system's performance and durability will decrease and the heat dissipation requirements will increase. Therefore, in this study, we developed two cooling designs for the ISG motor and inverter, and then carried out both a model analysis and an experiment on the fluid flow and thermal characteristics of the system under various operating conditions. As the outdoor temperature increased from 25 °C to 95 °C, the coil temperature of the air-cooled motor increased by about 82 °C. Under the harsh-air condition of 95 °C, the coil of the air-cooled motor increased to a maximum temperature of about 158.5 °C. We also determined that the temperature of the metal-oxide-semiconductor field-effect transistor (MOSFET) chip in the liquid-cooled inverter increased to a maximum temperature of about 96.8 °C under a coolant flow rate of 4 L/min and a coolant temperature of 65 °C. The observed thermal performance of the ISG motor and inverter using the proposed cooling structures was found to be sufficient for heat loads under various real driving conditions for a hybrid electric vehicle (HEV). Keywords

Evaluation of the Effect of Operating Parameters on Thermal Performance of an Integrated Starter Generator in Hybrid Electric Vehicles

“…The temperature of each component was estimated to increase by approximately 95 C when the ambient temperature increased from 25 C to 105 C due to increased heat generation in the motor. This is consistent with the result of Kim [20]. The ISG has a durability limit temperature of 200 C as it has a coil with an N-type insulator.…”

“…However, the temperatures of the major components increased as the conduction of the heat from the motor parts to the flange and bracket due to the cooling performance of the centrifugal cooling fan decreased significantly. Kim's [20] analysis of the ISG system also confirms a significant improvement in the heat dissipation performance with the wind volume, which changed with respect to the ISG speed. In a vehicle, components can be exposed to various climatic conditions depending on the operation environment.…”

“…A structural improvement design that can improve the conduction heat transfer performance at low speeds must be implemented together with an internal flow passage improvement design that improves the convection heat transfer performance at high speeds. This occurs by reducing the resistance in the inside flow passage and modifying the heat transfer structure by expanding the contact surface between the housing and the motor [20]. Table 6.…”

Investigation of Electromagnetic, Thermal and Mechanical Characteristics of a Five-Phase Dual-Rotor Permanent-Magnet Synchronous Motor

“…In [30], the steady-state temperature field of induction motor with water cooling used for a miniature electric vehicle is investigated by the 3-D FEM simulation. Ref [31,32] mainly concentrates on the formulations used to predict the convection cooling and calculate the heat dissipation coefficient within the machine. In [33], the authors investigate the thermal distribution and calculated the convection heat transfer coefficients of dual-rotor permanent magnet induction machine.…”

“…Therefore, heat dissipation is an important issue that should be considered in the motor design. The heat dissipation coefficient of different portions [26][27][28][29][30][31][32][33], such as air gap, outer surface of the casing and the end windings, is important to calculate temperature accurately. In [27,28], the thermal field distribution, cooling effects of the forced-air cooling and water cooling systems, heat-dissipation conditions and thermal-measuring system of CSPMSMs are analyzed by the two-dimension (2-D) and three-dimension (3-D) finite element method (FEM) simulation.…”