Investigation of Eddy Current Loss and Structure Design with Magnetic-Thermal Coupling for Toothless BLDC High-Speed PM Motor

Abstract

Brushless direct current (BLDC) permanent magnet (PM) synchronous motors are in high demand for ventilator applications owing to their high speed, high efficiency, and other significant features. However, it has become an important problem in eddy current loss calculations with high-speed motors, which leads to low motor (ventilator) life and PM demagnetization. This paper focuses on the eddy current loss calculation and the structure improvement design for the two-pole 90 W, 47,000 r/min toothless BLDC motor. First, the influencing factors of eddy current loss are comprehensively investigated, and a multiparameter improvement methodology is proposed accordingly. Second, by finite element analysis (FEA), the effective winding length ratio and the number of parallel wires were mainly researched for the winding, and the influence on the eddy current loss and the efficiency was determined, providing a reference for BLDC high-speed motors. This study has resulted in a 34.75% reduction in the winding losses, and a 4.6% increase in the efficiency of the improved model compared with the original design. Third, the new rotor structure is proposed, saving PM volume 15% more than original. THD of gap flux density is decreased 20.97%; the eddy current loss in the new rotor is decreased 22% more than original. Furthermore, by coupling simulation of the magnetic–thermal field, the maximum temperature of winding of the improved model is 13.4% lower than that of the original model at the thermal steady state. Finally, the electromagnetic and thermal properties simulation results were verified by testing the prototype. It is of great significance to the structure design and efficiency improvement of the BLDC high-speed motor.

Optimal Rotor Design and Analysis of Energy-Efficient Brushless DC Motor-Driven Centrifugal Monoset Pump for Agriculture Applications

“…FEM simulation entails executing a comprehensive design algorithm that incorporates a step-bystep design process, access to data libraries such as standard wire gauges and magnetic material properties, along with interactive input and output capabilities for enhanced functionality [41,42]. The design of a PM motor control system utilizes the MagNet (v7.1.1) software, specifically focusing on enhancing speed control for these motors [43,44]. It provides a comprehensive overview of the system's functionality and design approach.…”

Analysis of Inverter Circulating Current and Magnetic Potential for Flux-Weakening Drive of BLDCM

“…BLDCM is a trapezoidal wave brushless motor that uses Hall sensors to detect the rotor position. It is controlled by a six-step commutation method of the stator winding, which is based on the rotor position [1][2][3]. The BLDCM offers several advantages, including a simple structure, excellent speed regulation performance, and high efficiency.…”

Analysis of Eddy Current Loss of 120-kW High-Speed Permanent Magnet Synchronous Motor

“…Several studies have been conducted to calculate the rotor eddy current loss of the PM motors [1][2][3][4][5][6][7]. For the axial flux permanent magnet motor, the 2D analytical model cannot accurately calculate the eddy current loss of permanent magnets.…”

“…After verification, it was found that this method can significantly improve the efficiency of motor design optimization. Du et al [4] developed a multi-parameter improvement method for high-speed motor design. In part of the winding design, after a large amount of data analysis, the relationship between the two parameters and eddy current loss is summarized.…”