In-wheel surface-mounted permanent magnet motor design for light electric vehicle based on drive cycle WLTC Class 1

Abstract

Relevance: For designing traction electric motors, the approach focused on the motor operation at the rated mode point traditionally dominates. However, electric vehicle motors constantly operate in a wide range of torque and angular velocity changes. Accordingly, it is advisable to design an electric machine so that the zone of its optimal operation (maximum efficiency) is located in the area where the motor operates for the most time in the drive cycle. A literature review shows that such an approach makes it possible to increase the efficiency of the traction motor and with it the overall efficiency of the electric drive system. The purpose of this article is to develop an in-wheel traction surface-mounted permanent magnet synchronous motor (SPMSM) for a light electric vehicle – a high-speed electric bicycle – based on the new drive cycle WLTC Class 1 for light electric vehicle. Methods: For this purpose, a histogram of the combination of angular velocity and torque was obtained for the light electric vehicle under study while executing the specified drive cycle. According to the determined from the histogram range where the drive operates most often, the parameters of the experimental SPMSM were determined, moreover, for its operation in two regions of angular velocity control – with constant torque and constant power. In the MATLAB/Simulink environment, an SPMSM model was built taking into account copper and core losses, based on which the operational efficiency of the experimental (with two region of angular velocity regulation) and typical (with single region of angular velocity regulation) SPMSMs were studied. These studies provided information for the construction efficiency maps of these motors in the Surfer environment. A comparison of the operational efficiency of the light electric vehicle under study in the drive cycle, separately with the experimental and typical motors, was carried out by modeling in the MATLAB/Simulink environment using the Energetic Macroscopic Representation (EMR) method. The results of the study showed a decrease in electricity consumption for the execution of the drive cycle by the light electric vehicle with the experimental SPMSM by 2.37 %, as well as an increase in regenerative braking energy by 3.62 % compared to the typical motor. Conclusions: The results obtained confirm the effectiveness of the decisions made – SPMSM with two-region angular velocity regulation and the correspondingly obtained based parameters makes it possible to halve its rated power and simultaneously increase the overall efficiency of the electric bicycle drive system.