The carrier frequency of the inverter is to modulate a lower signal frequency to a relatively higher frequency. The higher frequency modulated by the low frequency is called the carrier frequency, also called the fundamental frequency.
When the carrier frequency is high, the current waveform is sinusoidal and smooth. In this way, the harmonics are small, but the interference is relatively large, and vice versa. When the carrier frequency is too low, the effective torque of the motor decreases, the loss increases, and the temperature increases and the dust is high. On the contrary, when the carrier frequency is too high, the frequency conversion The loss of the motor itself increases, the temperature of the IGBT rises, and the rate of change dv/dt of the output voltage increases at the same time, which has a greater impact on the insulation of the motor.
The carrier frequency of the inverter is the frequency that determines the number of times the inverter’s power switching devices (such as: IGBT) are turned on and off.
It mainly affects the following aspects:
1. The power loss of the power module IGBT is related to the carrier frequency. When the carrier frequency increases, the power loss increases, and the heat of the power module increases, which is not good for the inverter.
2. The influence of the carrier frequency on the waveform of the secondary current output by the inverter:
When the carrier frequency is high, the current waveform is sinusoidal and smooth. In this way, the harmonics are small, the interference is small, and vice versa, when the carrier frequency is too low, the effective torque of the motor decreases, the loss increases, and the temperature increases. On the contrary, when the carrier frequency is too high, the loss of the inverter itself increases. , IGBT temperature rises, and the rate of change of output voltage dv/dt increases, which has a greater impact on motor insulation.
3. The influence of the carrier frequency on the noise of the motor: the higher the carrier frequency, the smaller the noise of the motor.
4. The carrier frequency and the heating of the motor: the higher the carrier frequency, the less the heating of the motor.
In actual use, the above points should be integrated, and the carrier frequency of the inverter should be selected reasonably. Generally, the larger the motor power, the smaller the load rate option.
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