CN
Home > News > Industry News

Learn about the role and characteristics of artificial power networks in the field of electromagnetic compatibility

1、 What is an artificial power network

Artificial power supply network, also known as power impedance stabilization network, is an important electromagnetic compatibility testing device, mainly used to measure the continuous disturbance voltage of switching power supplies emitted along power lines to the grid. The artificial power supply network provides stable impedance for the measurement switching power supply in the RF range, and combines the measurement switching power supply with the high-frequency artificial power supply network on the power grid

① The isolator capacitor C3 is used to isolate the power supply voltage, prevent it from being added to the measurement terminal, and select different capacitors for different interference frequencies. Therefore, the radio frequency interference signal can be coupled to the measurement/signal terminal.

② The purpose of the analog hand is to reproduce the effect of the user's hand. When interfering with the measurement of non grounded hand-held electrical equipment, it should be connected to the analog hand for measurement. The measurement circuit uses the measurement circuit recommended in publication CISPRl4 and the measurement method recommended in publication CISPRl4.

③ Inductive filter L1 and capacitors C1, C2. Their function is to prevent RF interference signals from being transmitted from the power supply to the test equipment, and also to prevent interference signals from the test equipment from entering the power supply, thereby playing an isolation role.

④ The controller is completed by a button switch, and the measurement is controlled by the switch. The "Line Selection" switch controls "ground wire" and "between lines", and makes selections based on measurement needs during the measurement process. Another set of switches controls the frequency range and attenuator, selecting frequency range buttons based on different interference frequencies. Press the attenuator button before measuring. Attenuated signals should not normally be used when measuring interfering signals. The 20dB attenuator can only be used when the interference signal is too large and exceeds the interference field strength measurement range.

⑤ The 20dB attenuator consists of a non-type network with a characteristic impedance of 50 Ω. When measuring interference signals, the attenuator provides a safe protection circuit for test instruments and equipment to prevent equipment from being burned down due to excessive interference pulses. Therefore, the attenuator must be pressed before testing. When the interference signal has sufficient reading on the interference field intensity meter, the attenuator should be disconnected to allow the signal to pass directly, in order to eliminate the error introduced by the attenuator and improve the measurement accuracy.



国产电磁兼容仪器设备


2、 Characteristics of artificial power supply networks

1. The test phase line can be manually selected or automatically switched through software;

2. Comply with CISPR16-1 standards, which can be tested in accordance with EN, CISPR, FCC, ETS, VCCI, and VDE standards;

3. The frequency range is 9kHz - 30MHz, which can be used for DC - 63Hz power supply conduction test;

4. Built-in ammeter, which can measure the EUT absorption current according to CISPR switch operation and 14-1 requirements for measuring intermittent interference with a kara analyzer; The interference is separated and the interference voltage is coupled to the receiver.


3、 Classification of artificial power supply networks

There are V-type and △ type artificial power supply networks; V is an artificial power supply network for measuring asymmetric voltages, and △ is an artificial power supply network for measuring symmetric and asymmetric voltages.

Symmetrical Voltage: The RF disturbance voltage between two conductors is commonly referred to as the differential mode voltage

Unsymmetrical Voltage: Specifies the wire or terminal or voltage between ground references

Asymmetric voltage: The RF voltage between the electrical midpoint and reference point of two wires, also known as the common mode voltage.


4、 Artificial power network function

1. Provide channels for 50Hz municipal power. Because the inductance on the grid side is very small (50) μ H) "It is not enough to form a large impedance at the mains frequency, so mains power can provide electrical energy for the test object, while the capacitance on the side of the grid (1)" μ F) Grid interference signals can also be further attenuated.

2. By approaching the coupling capacitance (0.1 μ F) The RF disturbance signal generated by the switching power supply enters the receiver.

3. Stable impedance. Due to the different impedance of each power grid, the disturbance voltage value of the switching power supply is also different. Therefore, the standard specifies a uniform impedance (50 Ω) to facilitate the comparison of test results with each other.

4. Isolate and measure the radio frequency electromagnetic interference generated during the operation of the switching power supply (the measurement frequency is 0.15 MHz to 30 MHz). Using the high impedance of network inductors at RF can prevent RF interference signals generated by switching power supplies from entering the power grid.


国产电磁兼容仪器设备


5、 Requirements for artificial power supply networks

The purpose of using an artificial power supply network is to connect the network between the receiver power plug and the power supply, so as to have a specific high-frequency impedance between both ends of the receiver power supply, and isolate the power supply, thereby using an unbalanced input interference meter to measure symmetric and asymmetric interference voltages. The network should also include a filter section for filtering radio frequency interference present in the power supply system. If necessary, auxiliary filters should also be added. Within the measured frequency range, the impedance of the filter should be sufficiently high to avoid affecting the impedance characteristics of the network. The impedance between the two ends of the power supply AB needs to be connected together, with an impedance to ground of 150 ± 20 Ω and a phase angle not exceeding ± 20 °.




keywords: EMCLISNEMC test
Copyright © 深圳市霍达尔仪器有限公司 备案号:粤ICP备18007893号 百度统计 站点地图
技术支持:神州通达网络
首页
电话
留言