The principle of the frequency converter is to apply the principle of frequency conversion technology and microelectronics technology to control the power control equipment of the AC motor by changing the working power frequency of the motor, and convert the power frequency AC power with fixed voltage and frequency into voltage or variable frequency Alternating current devices are called "frequency converters".
The waveform output by the frequency converter is an analog sine wave, which is mainly used for speed regulation of three-phase asynchronous motors, also called frequency converters. The frequency converter is mainly composed of rectifier (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, a detection unit, and micro-processing unit. The frequency converter mainly adopts the AC-DC-AC method (VVVF frequency conversion or vector control frequency conversion). First, the industrial frequency AC power supply is converted into DC power supply through the rectifier, and then the DC power supply is converted into AC power with controllable frequency and voltage for supply Electric motor.
The 220V to 380V frequency converter converts the power frequency AC 220V power supply into a DC power supply through a rectifier (voltage doubler rectification) and then converts the DC power supply into a three-phase 380V AC power supply with controllable frequency and voltage to supply the motor.
One is to run a single-phase alternating current through the three-phase input of the drive. If the voltage is correct, the drive should operate normally. It should be noted that you must reduce the drive quota. The specification of the input diode assumes that the constant power load of the driver will be distributed among the three branches of the rectifier.
To obtain three-phase AC power from single-phase AC, you need to rectify the single-phase AC line to DC power, and then transport the DC power back through the inverter to obtain controlled three-phase AC power.
The typical variable frequency three-phase drive is exactly what I described above: the rectifier, then the inverter. But large three-phase frequency converters usually have terminals for three-phase AC line input, DC bus, and three-phase motor output. If you have these terminals, you have two options.
If the same load is distributed to only two legs, these diodes will get hot. The internal bus capacitors will also heat up because they will see more ripple current without the third phase. Please contact the drive manufacturer for derating information.
If the driver has a DC bus terminal, another option is to skip its internal rectifier and use an external rectifier. The single-phase AC power is rectified, and then the DC power is used as the input of the drive. This can avoid drive derating.