Single-phase AC motor typical speed control program is voltage regulator speed. Such as the fan of the slow file, medium gear, fast file, is the application of voltage regulation. Single-phase AC motor start-up need to start the capacitor, if there is no start capacitor, direct power start, there will be dead ends, need to use foreign help to start. The general three-phase output of the inverter vfd for the capacitor with the motor can not be used. The capacitor removed, and then connect the capacitor line and running the line, the shared line were connected to the inverter vfd, you can speed, strength than before. Because the motor phase angle is 90 degrees, so the inverter vfd should be specially designed, will have high efficiency, positive and negative is also easy to achieve. There is a special Single phase vfd for single-phase motors. 0.75kw-2.2kw low voltage 220v single-phase vfd.
Single-phase motors generally do not use general-purpose inverter vfd speed. If you use, you can single-phase 220v input, three-phase output of the inverter vfd's three output terminals (U, V, W), then any two ends, the output single-phase variable frequency power supply. In the output side of a series of inductance enough inductance, used to isolate the single-phase motor capacitor on the inverter vfd hazard (while the high-frequency carrier frequency converter to play a certain role), and protect the motor capacitor. This method is only applicable to low-power single-phase capacitor running and shaded pole motor, not suitable for centrifugal switch with the ideal motor.
Use this method to be careful to match the output voltage of the inverter vfd with the input voltage of the single-phase motor. The inverter vfd should have enough capacity (three times more power than the motor). Series inductance should have enough inductance and flow through the current, the magnetic material of the inductor should match the carrier frequency of the frequency converter.