Keun-Young Yoon

Interior permanent magnet motors are widely used in applications requiring high power density and high efficiency due to their high torque-generating capabilities. Recently, given the price fluctuations and unstable supply of rare earth permanent magnets, alternative configurations with reduced use of permanent magnets are being sought. Among the various candidates related to this, the consequent-pole type rotor structure can halve the number of permanent magnets used compared with conventional structures. However, in a no-load analysis, the waveform of the back electromotive force becomes asymmetric, generating a harmonic component. As a result, there is a disadvantage that the torque ripple increases. To overcome these shortcomings, we propose a novel rotor structure that applies a consequent-pole structure to an embedded permanent-magnet motor structure, wherein a number of permanent magnets are arranged in a flared structure to constitute a single polarity. In the proposed flared-structured magnet arrangement, it is possible to adjust the angle of the permanent magnet and the polar angle to mitigate the asymmetry of the back-EMF waveform. The proposed structure was optimized with a genetic algorithm and a prototype of the optimal model was constructed and experimentally evaluated to verify its validity. Finally, the performance improvement and validity of the proposed structure were verified by comparing the analysis results of the optimal model with the experimental results.

Unlike the winding structure of existing three-phase single winding motors, the winding structure of the dual winding motor (DWM) contains a master part and two slave parts. Thus, when the master part fails, it can be driven using the remaining slave part. It is applicable to various electric parts driving the integrated electric brake (IEB) system; thereby securing the high reliability of vehicle parts. However, in the existing DWM, there is an overheating problem owing to the increase in current because it operates with half the motor during the faulty mode. Therefore, a compensation method for the increase in current in a faulty mode was employed by increasing the stacking length of the DWM. However, although it solves the overheating problem of the DWM in the faulty mode, the motor output performance and braking performance of the IEB system are degraded in the normal mode because of the change in the motor control parameters. Thus, in this paper, we propose a DWM with winding switching (WS) to simultaneously solve the DWM overheating problem in the faulty mode and the DWM’s performance degradation problem in the normal mode. The output performance of the DWM with an increased stack length and the previously developed base model are compared to verify the performance of the proposed DWM with WS. As a result of the comparison, unlike the DWM with an increased stack length, in which the maximum speed is reduced by 20.5% compared to the existing base model during quick braking in the normal mode, the proposed DWM with WS has no performance degradation. In other words, it is confirmed that the proposed DWM with WS effectively solves the overheating problem during faulty mode, while simultaneously solving the performance degradation problem of the IEB system during the normal mode.