What harm can inverter harmonics cause? With the continuous improvement of industrial automation, inverter air compressors have gradually become the mainstream products on the market, and inverters have also been widely used. The inverter of the variable frequency air compressor adjusts the voltage and frequency of the output power by turning on and off the internal IGBT, and provides the required power voltage according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation. However, the harm caused by the large number of applications of the inverter cannot be ignored. In the motor field, to a certain extent, the normal use of the motor may cause damage and affect normal operating conditions.
The inverter energy-saving transformation effect of the inverter air compressor is obvious, but the harmonic pollution problem of the inverter has become a serious problem at present. The problems encountered by different enterprises in the application of inverters are different. In summary, harmonics will mainly cause harm to some equipment. Filter devices such as reactors need to be installed to solve harmonic problems, which also brings copper applications. opportunity. Let's elaborate on which equipment will be harmed by harmonics?
What harm can inverter harmonics cause?
Current harmonics will increase copper loss, and voltage harmonics will increase iron loss. The overall effect is to increase the temperature of the transformer, affect its insulation capacity, and reduce the capacity margin. Harmonics may also cause resonance between the transformer windings and line-to-line capacitance, and cause the core magnetic flux to saturate or skew, resulting in noise.
The impact of output harmonics on the motor is mainly caused by the additional heating of the motor, which leads to the additional temperature rise of the motor. The motor is often derated. Due to the distortion of the output waveform, the repeated peak voltage of the motor is increased, which affects the insulation of the motor. Causes motor torque ripple and increased noise.
3. Switching equipment
Due to the presence of harmonic currents, the switching equipment generates a high di / dt current change rate at the instant of startup, which increases the peak value of the transient recovery voltage and destroys the insulation.
4.Power capacitor bank
Standard specifications of general capacitors stipulate that their maximum current is only allowed to be overloaded by 35%, but in actual operation, severe overload often occurs due to the influence of harmonics. Because the impedance of a capacitor decreases with increasing frequency, when harmonics occur, the capacitor becomes a sink point, and a large amount of current flows in, resulting in overheating, increased dielectric stress, and even damage to power capacitors. When the impedance of the capacitor and the line reaches the resonance condition, vibration short circuit, overcurrent and noise will occur.
Meters and other measuring instruments, due to harmonics, will cause the induction turntable to generate additional electromagnetic torque, causing errors and reducing accuracy.
The current contains harmonics, which will generate additional torque and change the operating characteristics of the appliance, causing misoperation.
Others, such as lighting equipment, communication equipment, computer equipment, and carrier frequency remote control equipment, are susceptible to harmonic interference and affect their normal work or reduce their service life.
7. Power electronics
In many occasions, electronic equipment often generates harmonic current sources, and it is easy to feel harmonic distortion and malfunction.