With the increasing application of high-power loads, VFDs have also been widely adopted. The VFD can provide the appropriate power supply voltage according to actual needs, thereby achieving the purpose of energy saving. The VFD can precisely control the rotational speed of the motor, which is very important for situations requiring precise operation. Since the VFD can automatically adjust the operating status according to load changes, it reduces the frequent start and stop of equipment, which helps to extend the service life of the equipment. The VFD also can adapt to different working environments and load requirements, and has wide application space, whether for small household appliances or large industrial equipment.
The input current of the VFD is non-sinusoidal, and the output voltage is also non-sinusoidal. This will result in the existence of harmonic current and harmonic voltage. Harmonics may cause the following problems:
1. Power supply voltage distortion, decreased voltage quality, and increased line loss.
2. Increased motor heating, decreased efficiency, reduced power factor, and increased vibration and noise.
3. Resonance with the wire capacitance generates overvoltage, which harms insulation and causes overvoltage breakdown.
4. Causes overheating of capacitors, increases loss, and may lead to electrical breakdown or thermal breakdown.
5. Increases the imbalance degree of the three-phase input current of the circuit.
6. Reactive power problem: The input part of the frequency converter, due to the three-phase bridge rectifier circuit composed of nonlinear diodes, capacitor filtering, and the discreteness of diode parameters, the non-sinusoidal current waveform caused by these factors will lead to increased reactive power loss and reduced power factor.
Is there an effective solution available to solve the problems caused by the use of VFD? Yes, we recommend solutions as below:
1.Active power filter(APF): Active Power Filter is a perfect and comprehensive solution for addressing power quality issues in the grid,such as harmonics, reactive power, and three-phase load imbalance. The APF connected in parallel to the grid, canpromptly detect harmonics in the grid, generate a counteracting compensation current through the converter, and dynamically filter out the harmonics.The operation of the APF is unaffected by various load types and grid structures. The APF can fully achieve dynamic reactive power compensation, and ultimately improving the power factor, mitigating the harmonic, controlling three-phase load current imbalance, thus comprehensively addressing various power quality issues in the grid.
2.Static var generator(SVG): Based on the principle of a voltage source inverter, the SVG controls the magnitude and phase of the inverter AC voltage, thus achieving the purpose of reactive power and harmonic compensation. Due to the very high switching frequency, the SVG can compensate for rapidly changing reactive loads and achieve very high compensation accuracy. SVG is the best solution in the field of reactive power control.
3.Hybrid compensation cabinet: This solution integrates fixed capacitor compensation, SVG, APF and other compensation schemes, and can simultaneously compensate reactive power and mitigate harmonics.
Post time: May-09-2026