Usually, the device that converts constant voltage and constant frequency alternating current into variable voltage or variable frequency alternating current is called "frequency converter".

Second, the working principle of frequency converter is introduced:

1. The equipment must first convert three-phase or single-phase alternating current into direct current (DC). Then direct current (DC) is converted into three-phase or single-phase alternating current (AC). The inverter changes the output frequency and voltage at the same time, that is, it changes n0 on the motor running curve, so that the motor running curve moves down in parallel. Therefore, the inverter can make the motor get a larger starting torque with a smaller starting current, that is, the inverter can start a heavy load.

2. Diagram;

(1) inverter wiring diagram:

(2) Schematic diagram of frequency converter speed regulation: