Solution for EMC Problem of EV AC Charging Pole

Solution for EMC Problem of EV AC Charging Pole

As an electrical and electronic device connected between the urban power grid and electric vehicles, the electromagnetic compatibility of AC charging piles must have strict requirements. This can ensure that it operates safely and stably in the power grid without interfering with other equipment.

However, most charging piles have more or less problems in the presence of electromagnetic interference. Some can recover on their own after the interference is removed, and some simply stop working or even cause hardware damage.

What is Electric vehicle AC charging pole?

Electric vehicle AC charging piles are fixed on the ground or walls and installed in parking lots or charging stations of public buildings and residential areas. They use conduction to provide human-computer interaction interfaces and AC charging interfaces for electric vehicles with on-board chargers, and have Special device with corresponding measurement, control and protection functions, the power is generally not greater than 7kw. At present, the working voltage of AC charging piles mainly produced in China is 220V (±15%), and the rated output current is 32A (seven-core socket), 16A (three-core socket).

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How to Solve the EMC Problem of EV AC Charging Pole?

The ferrite magnetic ring is essentially an absorption filter, which can convert the energy of high-frequency interference into heat loss. In the low frequency band, the magnetic ring exhibits a very low inductive impedance value and does not affect the transmission of useful signals on data lines or signal lines. In the high-frequency band, the impedance increases, absorbing and dissipating the high-frequency EMI interference energy in the form of heat energy.

For electrical fast transient pulse group interference, the main frequency of the rising edge is 40~100MHz. The simplest and most effective way to suppress fast transient pulse group interference is to connect a ferrite absorption magnetic ring in series on the line and use the ferrite magnetic ring The characteristic of rapid increase in the resistance component in the high frequency band converts the energy of fast transient pulse group interference into heat and dissipates it. 

In the fast transient pulse group test, the main abnormal phenomenon at the charging pile is the disappearance of the display screen and indicator light. As needed, consider the signal/control between the power input port connection line of the charging pile, the touch screen circuit board and other components. Put one or several magnetic rings on wires, communication lines, etc., and wrap them around several times to attenuate high-frequency interference.

For power cord input ports with larger rated power, the operating current is generally 16A (three-core socket), and a high-power slow-running magnetic ring needs to be selected.

When a wire flowing with a larger current passes through a ferrite magnetic ring, its low-frequency insertion loss will become smaller, and its high-frequency insertion loss will not change much. To avoid this, when using a magnetic ring on the power line, you can Pass the power cord and power return line through the ferrite magnetic ring at the same time, making sure they enter and exit at the same time.

In electromagnetic compatibility immunity tests, such as fast transient bursts,

Surges, damped oscillation waves, etc. will inevitably cause damage to the circuit of the device under test.

Cause some high-frequency interference; in the test of electromagnetic emission test, it also affects the electricity

Conducted and radiated emission limits for source ports are specified.

However, based on the strict requirements for the product, a suitable power filter is usually configured at the power port of the electric vehicle charging pile to effectively suppress external interference to the charging pile and prevent the electromagnetic noise of the charging pile itself from affecting the external power grid and space.

A commonly used power supply filter is composed of a choke and three capacitors.

Attention should be paid during installation: the leads at the input and output ends of the EMI power filter must be separated from each other to avoid reducing the filtering performance due to distributed capacitive coupling. The power filter is installed directly at the entrance of the power cord. Ideally, it should be connected to the shell, such as when installed on the product. Internally, the wiring should not be too long. The RF impedance of the filter housing to the ground must be close to zero. The contact surface must be clean, smooth, complete, and the contact is tight and stable. The filter should be installed close to the place where filtering is required, and its connecting wires must be shielded.

Consider the power of electric vehicle charging piles. Generally choose a single-phase power filter with a rated current of 16 A or more, and an insertion loss of not less than 40 dB above 1 MHz.

DOREXS will provide suitable single phase power filter for solving the EMC problem on EV charging station.

Such as model DAA1, DBA3, they are single phase, single stage power filter. And two stages model DEA4 also very popular use on EV charging station. The maximum current can reach 20A and the maximum voltage can reach 250VAC. It adopts a two-stage filter design and has excellent differential mode and common mode interference suppression characteristics. Is a high-performance AC noise filter.

DOREXS Manufacturing on EMI Filter

DOREXS has many years of experience in EMI filter manufacturing and is proficient in applying EMI filters to switching power supplies.

Moreover, DOREXS has multiple product certifications, including CE, ISO9001, UL and other certifications, which meet the technical requirements of European and American countries.

Contact us to get more EMI filters suitable for use in switching power supplies