Power Quality Solution for Automobile Industry

        The primary sources of electrical harmonic pollution in the automotive and shipbuilding manufacturing industries come from spot welders, DC motors, and variable frequency drives (VFDs).

• Spot Welders: These are typical single-phase impulse loads and harmonic power sources. Due to the two-phase short-circuit principle used in the welding machine, large current imbalances occur. The current harmonic distortion rate typically ranges from 10-30%, with harmonic frequencies primarily at the 5th to 13th orders.

• DC Motors: These are typical sources of harmonics and impulse loads. Harmonic current constitutes about 30% of the total current of the equipment, and harmonic frequencies vary with the load on the system, typically occurring at the 5th to 7th orders.

• Variable Frequency Drives: These circuits are generally composed of rectifiers, intermediate DC stages, inverters, and controllers. The current distortion rate typically ranges from 30-50%, with harmonic frequencies primarily at the 5th to 7th orders.