Let's first understand the function of a reactor, and then delve into the combined effect of a variable frequency drive circuit with a reactor.
There are many types of reactors categorized by their applications, such as current-limiting reactors, filtering reactors, and smoothing reactors.
A wide variety of reactors are used in power lines, serving functions such as reactive power compensation, resonance prevention, limiting short-circuit current, suppressing the AC component of DC power, limiting grid interference, preventing grid pollution, and absorbing harmonic currents to eliminate higher-order harmonics.
The Function of the Variable Frequency Drive Reactor:
A reactor is typically installed at the input or output terminals of a variable-frequency drive (VFD) to suppress the interference caused by the 3-5th harmonics generated by the VFD on the power grid. It also reduces the interference of the harmonics produced by the VFD on other components, improves the overall stability of the power grid, enhances power factor, and can limit abnormal voltage fluctuations of the power grid, preventing shock currents and smoothing waveform effects on the normal operation of the VFD.
Under what circumstances is it necessary to add an output reactor?
When the motor cable is longer (specific details can be found in the corresponding inverter manual, usually provided with the length), adding an inductor can eliminate or reduce the effect of reflected waves on the motor.
When the motor insulation is poor (e.g., withstand voltage 1000V, 1200V), non-specialty variable-frequency motors require an addition of an inductor.
When it's necessary to reduce the impact of PWM reflection waves and dV/dT on the motor, an inductor should be added.
Under what circumstances is it necessary to add an input inductor?
One: When the power factor of the variable frequency inverter needs to be compensated;
During peak power events (e.g., lightning strikes, overvoltage operations, etc.).
When the inverter capacity is significantly smaller than the upstream power transformer (e.g., less than 10 times).
In the case of variable frequency drives, there is a need to improve power factor and reduce harmonic THD.
