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

Dong Hyun Lim ,Sung Chul Kim ,Moo‐Yeon Lee

doi:10.3390/en8088990

Abstract

The belt-driven-type integrated starter generator motor in a hybrid electric vehicle is vulnerable to thermal problems owing to its high output power and proximity to the engine. These problems may cause demagnetization and insulation breakdown, reducing the performance and durability of the motor. Hence, it is necessary to evaluate the thermal performance and enhance the cooling capacity of the belt-driven type Integrated Starter Generator. In this study, the internal temperature variations of the motor were investigated with respect to the operating parameters, particularly the rotation speed and environment temperature. At a maximum ambient temperature of 105 °C and rotation speed (motor design point) of 4500 rpm, the coil of the motor was heated to approximately 189 °C in generating mode. The harsh conditions of the starting mode were analyzed by assuming that the motor operates during the start-up time at a maximum ambient temperature of 105 °C and rotation speed (motor design point) of 800 rpm; the coil was heated to approximately 200 °C, which is close to the insulation temperature limit. The model for analyzing the thermal performance of the ISG was verified by comparing its results with those obtained through a generating-mode-based experiment

Highlights

The demand for hybrid vehicles is increasing along with the interest shown by consumers for environmentally friendly automobiles
Because the thermal and heat dissipation characteristics of an Integrated Starter Generator (ISG) employing the forced air-cooling method may change with the operating speed and environment temperature, a thermal flow analysis was conducted with varying operating parameters
The present study confirmed the effects of the operating parameters on the thermal performance of an integrated starter generator motor in a hybrid electric vehicle

Summary

Introduction

The demand for hybrid vehicles is increasing along with the interest shown by consumers for environmentally friendly automobiles. The ISG can stably satisfy increases in the power demand and it is a key component for realizing additional fuel efficiency improvements owing to its idle stop and go function (to reduce fuel consumption when idling) and its potential for regenerative breaking (to recover the vehicle’s inertial energy as electric energy when the vehicle decelerates) [4,5]. Unlike the direct-coupled-type motor, which is directly coupled to the engine’s crankshaft, the belt-operated ISG can be applied without significant alterations to the engine design because it employs connection methods similar to those of existing vehicle-mounted generators. It is installed near the 1.2–1.5 kW vehicle-mounted alternator and it requires a high power density to meet the output level of 5 kW

Methods

Results

Conclusion