Why is the input current of the inverter smaller than the output current? -Solutions - Huaqiang Electronic Network

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The input current of the inverter is related to the power required by the motor, the power supply voltage, the efficiency of the inverter, and the power factor. The power factor of the frequency converter varies with the impedance of the power supply. Low impedance results in a lower power factor, and high impedance results in a higher power factor. Since the load carried by the inverter is a motor, the power factor of the input and output is different. The power factor of the output of the inverter is higher than the power factor of the input.

The current of the motor depends on the required shaft power. The power factor of the motor is usually lower than the power factor of the inverter. Due to this feature, the input current of the inverter will be smaller than the motor current driven. If there is a 15KW/380V 4-pole motor, drag it with a corresponding inverter. Now calculate the relevant parameters as follows:

As can be seen from the above, the input current of the inverter is smaller than the output current. Some people think that the following factors will also cause the inverter's input current to be smaller than the output current.
The output current of the inverter is provided by the inverter. The waveform of the pulse width modulation current approximates the sine. Only when the output is increased, the load can be guaranteed, which is generally greater than 10% of the input.
When the inverter is running, the current at the input and output terminals contains higher harmonics, and it is difficult to measure the phase angle. Measurement errors are also generated according to the traditional measurement method.
Conventional meters measure the current and power consumption of harmonic components, there is a certain error, but regardless of the measurement results, the input power factor of the inverter is generally higher, about 0.95 or more, and the motor input power factor is generally about 0.85. , then consider from the conservation of energy. The output current must be greater than the input current to satisfy the equation balance.