AHF Application-Battery charging station

Project Overview:

Electric vehicle?battery?charging station?used a large number of switch power supply,. it converts AC?power to DC?to charge the battery.This converting process generates a?large number of third harmonics, and the third harmonics?will be superimposed on?the N?line,which leads to large current and overheat on?N line,The normal N?line current value usually less than 30% phase current for a three-phase approximately balanced load. But,No matter how?intelligent charging system do the load distribution, the?fast change of?charging load will still leads to a instaneous?phase imbalance.?And in addition to the influence of harmonic current, the N line current value rise to?280% of the phase current?value.

?Analysis of Harmonic features about Battery charging :

In the intelligent charging cabinet, a large amount of switch power supply is used to charge the battery, which caused?third harmonic current?and lead to?the N?line current?become large.?Sometime, it may also endanger the safe operation of the input power grid and all kinds of electrical equipment connected in the power grid. The main effects are as follows:

1. Increase the transformer burden.

The transformer will produce eddy current loss and hysteresis loss due to harmonic current, which will cause the fast temperature?rise?of the transformer core and cause low equipment?efficiency; Meanwhile, it will damage the insulation and even cause short circuit fault of the equipment. In order to restrain the temperature rise, the transformer needs to reduce the capacity.

2. Accelerate cable aging and shorten service life

Due to the harmonic current, the rms?current value will be?larger than the fundamental current?in the cable. At the same time, due to the skin effect, the harmonic resistance will be increased, thus will increase the?line loss, the transmission capacity will be reduced, the cable aging will be accelerated, and the service life will be shortened.

Improvement method:

Coepower 150A wall-mounted AHF were installed to reduce the third harmonic and the N line current..

Improvement?effect:

Coepower 150A wall-mounted AHF were installed?and achieve ideal effect, which was highly appreciated?by the customer.

1. The N line current is 240.5A before starting AHF, 35.7A after starting AHF..

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