The reactor in the circuit generally has two functions:
(1) suppress surge (voltage, current).
(2) restrain harmonic current.
The reactor can be divided into input reactor, output reactor and DC reactor. Different reactors have different functions in frequency converter.
Input reactor
It is used to limit the current impact caused by the sudden change of the grid voltage and the operation over-voltage, smooth the peak pulse contained in the power supply voltage, or smooth the voltage defect caused by the commutation of the bridge rectifier circuit, effectively protect the frequency converter and improve the power factor. It can not only prevent the interference from the grid, but also reduce the pollution of the harmonic current generated by the rectifier unit to the grid.
Output choke
The main function is to compensate the influence of distributed capacitance of long line (20-200m), reduce the leakage current of motor grounding, restrain the output harmonic current, improve the output high-frequency impedance, and effectively restrain DV / dt. Reduce the high frequency leakage current, protect the frequency converter and reduce the equipment noise.
DC reactor
Connected between the DC rectification link and the inverter link of the frequency conversion system, the main purpose is to limit the AC component superimposed on the DC current to a specified value, keep the rectifier current continuous, reduce the current pulse value, make the inverter link run more stable and improve the power factor of the frequency converter.
