Abstract : A simple and effective method for calculating the iron loss of a high-speed variable frequency motor under non-sinusoidal power supply is presented. Based on harmonic analysis, this method comprehensively considers the effects of power supply harmonics, motor core saturation, and skin effect, achieving high accuracy. Comparison with the results calculated using the finite element method demonstrates that this method also possesses higher accuracy.
Keywords : high-speed variable frequency motor; iron loss calculation; harmonic analysis method
1 Introduction
High-speed variable frequency motors are high-precision, high-speed asynchronous motors widely used in high-speed machining, turbomachinery, and flywheel energy storage. Compared to ordinary asynchronous motors, high-speed variable frequency motors use specialized medium-frequency inverters for power supply, operating at frequencies ranging from hundreds to thousands of hertz. As the frequency increases, the proportion of core loss in the total motor loss increases. Furthermore, harmonic components in the inverter output will generate additional iron losses in the stator and rotor cores. Considering the harsh heat dissipation conditions of high-speed motor rotors, this will affect the motor's service life. Therefore, it is necessary to further analyze the core loss of high-speed variable frequency motors to improve design accuracy. Currently, domestic calculation formulas for asynchronous motor iron losses are basically based on the assumption of a sinusoidal alternating magnetic field at power frequency. However, under non-sinusoidal power supply, the calculation model for core material iron losses changes. This paper analyzes the calculation of iron losses in asynchronous motors powered by frequency converters. The conclusions are applicable to medium- and low-speed frequency converter motors. However, the analysis does not fully consider the skin effect and the influence of the core material's frequency characteristics on the motor's iron losses, making it unsuitable for high-frequency frequency converter motors. Therefore, it is necessary to explore the calculation of iron losses in asynchronous motors under high-frequency non-sinusoidal power supply.
2. Iron loss calculation model under sinusoidal magnetic field
For details, please click: Calculation Method of Iron Loss for High-Speed Variable Frequency Motors Based on Harmonic Analysis
