Power filters are filter circuits consisting of capacitors, inductors and resistors, also known as "power EMI filters", or "EMI power filters", a passive bi-directional network, one end of which is the power supply, the other end is the load. So, what is the role of the power supply filter? Here's how.
A, the role of the power supply filter
The role of the power line filter is to prevent the electromagnetic interference generated by the equipment itself into the power line, while preventing the interference on the power line into the equipment. A power line filter is a low-pass filter that allows DC or 50Hz operating currents to pass through without allowing higher frequency EMI currents to pass through. The power line filter is bi-directional, which prevents interference on the power grid from entering the equipment to have an adverse effect on the equipment, so that the equipment to meet the requirements of the conduction sensitivity; but also prevents electromagnetic interference within the equipment through. Power line to the power grid, so that the equipment to meet the requirements of the conductive emission. Equipment capable of generating strong interference and equipment sensitive to external interference should use power line filters. Equipment capable of generating strong interference includes equipment containing pulse circuits (microprocessors), equipment using switching power supplies, equipment using thyristors, frequency conversion speed control equipment, and equipment containing motors. Sensitive circuits such as: devices using microprocessors, small signal analog circuits, etc..
Principle of operation
A power filter is a passive bi-directional network with a power supply at one end and a load at the other. The principle of the power filter is a kind of - impedance adaptation network: the greater the impedance adaptation between the input and output sides of the power filter and the power supply and load side, the more effective the attenuation of electromagnetic interference.
Second, the power filter manufacturers
Jinan and Kang Electronic Technology Co. > Xi'an Haonan Electronic Technology Co. Shandong Jinan Dongneng Electric Power Equipment Co. Shenzhen Kebit Trading Co. Shenzhen Jianli Electronic Co. ①The type of filter: industrial grade, military grade or medical equipment; ②The type of power supply for the application of filter equipment: AC single-phase, three-phase, DC, etc.; ③The rated voltage, current, structure and external dimensions of the filter, etc.; ④Other application-specific requirements, such as: withstand voltage, leakage current, operating temperature, etc. This is the first time that we have used a power supply filter in the market. Electromagnetic compatibility standards to choose Fig5.Various standards on the conductive emission of the required frequency band Because of the different standards on the conductive emission of the measurement of the different frequency bands, so in the selection of filters need to be considered prior to the equipment to be measured in accordance with the standard, and in the corresponding standard requirements of the band on the insertion loss requirements of the filter. The filter insertion loss requirements for the corresponding standard are presented in the frequency band required by the standard. Structure Power filters are generally designed as passive filters consisting only of resistors, capacitors, and inductors, with no active components such as transistors. The figure on the right is an example of a power filter. The power filter is connected to the power supply at the top, and there is a *** mode inductor at the power supply end, which means that the two power supply wires are wound around the core in the same direction, and if there is a *** mode signal on the power supply wires, the magnetic fields generated by the *** mode inductor will add up, so there is a larger impedance, and the differential mode signals generated by the magnetic fields in the *** mode inductor will offset each other, so they can flow through the *** mode inductor. **mode inductor. The current flowing through the power supply is mainly differential mode, but noise may also appear in the form of differential mode above. To suppress differential mode noise, you need to use a separate differential mode inductor, or have individual inductors for each phase. Special safety decoupling capacitors are used in power filters, which are divided into two categories: X-capacitors and Y-capacitors: X-capacitor: Suppresses differential-mode interference (interference between power lines). Y capacitors: Suppress **** mode interference (interference between groups of power lines to ground). Because Y capacitance increase will make the leakage current of the appliance increase, and the leakage current of the appliance has its own regulation range, so Y capacitance can not be too big, generally will be smaller than X capacitance. The X and Y capacitors are safety capacitors, meaning that their failure will not cause an electric shock or affect personal safety. Both have a self-healing effect, which restores insulation to the partially short-circuited portion of the circuit. The above is a small introduction to the role of power filters, I hope to be able to help you. For more information about power filters, please continue to pay attention to Tupaji learning to decorate. Tubapu online free for everyone to provide "each decoration offer, 1-4 local decoration company, 3 sets of decoration design scheme", and decoration to avoid pit strategy! Click on this link:/yezhu/zxbj-cszy.php?to8to_from=seo_zhidao_m_jiare&wb, you can get free Oh~