By using a magnetic field analysis simulation that accounts for control, the iron loss accounting for the PWM control carrier harmonics can be assessed.
In this example, the effects on iron loss when the modulation method for PWM control is changed are evaluated.
The current waveforms for the PWM 3-phase modulation and 2-phase modulation are shown in Fig. 1, and the frequency components of the current are shown in Fig. 2.
In this example, we compare the components at approximately 6,000 Hz, which is the carrier frequency of the PWM inverter. The carrier amplitude of the 2-phase modulation is larger than that of the 3-phase modulation.
The iron loss of the 2-phase modulation increases compared to that of the 3-phase modulation. This may be due to the carrier amplitude of the 2-phase modulation current, which is larger than that of the 3-phase modulation.
In general, switching loss is smaller with the 2-phase modulation. However, looking at the analysis results, we see that the iron loss of the 2-phase modulation increases. When considering overall system efficiency, the effect that different modulation methods have on iron loss must be obtained correctly.