## 5 Core Loss Calculation Results  
The no-load and load core losses of the PMSM stator at different speeds are shown in Figure 11. It can be seen from the figure that as the speed increased, the no-load loss of the stator core gradually increased. Under load conditions, the Id current in the constant torque region (0-3200 rpm) remained the same, and the magnetic field in the stator core of the motor was the same. As the speed increased, the frequency of the motor also increased, resulting in the loss of the stator core. When there was an increase in the constant power zone (3200-6000 rpm), due to the gradual increase of the Id current, the demagnetization effect was obvious, and the magnetic field in the stator core was weakened. Even if the speed increased, the motor frequency increased, and the stator core loss also decreased [29]. Figure 10: The amplitude of each harmonic component of the radial flux density of the tooth and the tangential flux density of the yoke. Under load, the core loss was decomposed into hysteresis loss (Ph), eddy current loss (Pe), and additional loss (Pexc). The decomposed core loss at different speeds is shown in Figure 12, and their proportion to the total core loss is shown in Figure 13. It can be seen from Figure 12 that the hysteresis loss accounted for most of the core loss. In the constant torque region, with the increase in speed, the hysteresis loss gradually increased; in the constant power region, the magnetic field became smaller due to the weak magnetic field, causing the hysteresis loss to decrease with the increase of speed. With the increase of speed, in the constant torque region, the eddy current loss and additional loss were increasing; in the constant power region, even if the magnetic field became smaller, due to the increase of the motor frequency, the influence on the increase of loss increased, the eddy current loss and the additional loss continued to rise. Figure 11: No-load loss and load loss of the motor at different speeds. Figure 12: Decomposed core loss under different speed loads. As shown in Figure 13, as the speed increased, the proportion of hysteresis loss, eddy current loss, and additional loss in the total core loss were constantly changing, and the proportion of hysteresis loss gradually decreased. Due to the increase in harmonic content, eddy current loss, and the proportion of additional loss, the rising speed of eddy current loss was higher than that of additional loss. The above analysis is the calculation result under the condition of sinusoidal current source loading. Under normal circumstances, the calculation result under the sinusoidal current source can meet the basic needs of motor electromagnetic field and motor performance research. However, the loss results obtained were ignored because the influence of inverter carrier harmonics is relatively small. Therefore, it is necessary to analyze the motor loss under SVPWM of the inverter. The A-phase current of SVPWM at different speeds is shown in Figure 14.  
The current is generated by the space vector pulse width modulation of the inverter. The main harmonic order of the PWM waveform is \((2\mathrm{i}-1)\mathrm{fc/f}\pm 2\), \((2\mathrm{i}-1)\mathrm{fc/f}\pm 4\), \(2\mathrm{ifc/f}\pm 1\), \(2\mathrm{ifc/f}\pm 5\) (\(\mathrm{i}=1,2,3,\dots\) ), where fc is the inverter carrier frequency, and f is the fundamental frequency. The carrier frequency of the motor controller is 7.5 kHz. When the motor is working at 5000 rpm, the main harmonic order was \(15\pm 2\), \(15\pm 4\), \(30\pm 1\), \(30\pm 5\), \(45\pm 2\), \(45\pm 4\), \(60\pm 1\), \(60\pm 5\),... Perform Fourier analysis on the phase A current at 5000 rpm gave the harmonic current amplitude under different harmonic orders, as shown in Figure 15.  
Figure 14: Space vector pulse width modulation (SVPWM) phase A current at different speeds. Figure 13: The ratio of core loss to total core loss under different speeds under load conditions.