Improving Thermal Analysis Accuracy of LPTN for Vehicle Claw-Pole Alternator by Calibrating Forced Convection Coefficients Based on Experimental Results

Ming Li,Yuejun An,Zhiheng Zhang

doi:10.1109/access.2019.2940508

Abstract

Claw-pole alternators are particularly important for vehicle power generation due to their low cost, simple design, and mechanical robustness. High and low temperatures around vehicle claw-pole alternators (VCPAs) change their internal temperature distributions, thus thermal analysis is required for designing VCPAs. Aiming at improving the accuracy of evaluating the temperature of VCPAs, a novel lumped parameter thermal network (LPTN) is proposed to analyze the steady-state temperature of a double excitation VCPA under various ambient temperatures. The forced convection coefficients are calibrated in order that the LPTN can simulate the real heat transfer of the VCPA. The nonlinear least square method is applied to obtain the calibrated coefficients within a range of the tested ambient temperatures. Moreover, the effectiveness of the proposed method is verified via simulation studies, whereby the results show that the proposed LPTN with calibrated convection coefficients can accurately evaluate the temperature of VCPAs. Finally, these results soundly supply the technical knowledge for the thermal analysis and facilitate selecting the optimal scheme for machine designers.

Highlights

Claw-pole motors are widely used in vehicle alternators due to their simple structure, robustness, and durability
In [14], a 3-D Lumped parameter thermal network (LPTN) model was employed for increasing the optimization efficiency of a permanent magnet (PM) claw-pole motor, by which the results show good performance with the improved motor
Rakotovao built a simplified LPTN for thermal analysis of a claw-pole machine, the thermal coefficients are obtained by analysis of computational fluid dynamics (CFD) and finite element analysis (FEA) [17]

Summary

Introduction

Claw-pole motors are widely used in vehicle alternators due to their simple structure, robustness, and durability. Lumped parameter thermal network (LPTN) is one of the important methods for thermal analysis, which is universally adopted to evaluate temperature in initial stage of motor design. In [14], a 3-D LPTN model was employed for increasing the optimization efficiency of a PM claw-pole motor, by which the results show good performance with the improved motor. These developments may improve the accuracy of thermal analysis but comes at the cost of increasing the computation time. The method of calibrating thermal coefficients has been used by researchers to improve the LPTN accuracy of claw-pole motors. O.Maloberti et al explored the variation of the forced convection coefficients with the VCPA speed, whereby the obtained conclusions provide some references for the VCPAs’ thermal analysis using LPTN [18]

Objectives

Methods

Conclusion