Design and application of electromagnetic compatibility of power supply filters

Filter 18.432M

Overview:
0 Introduction Electromagnetic compatibility (EMC) refers to the ability of electronic and electrical equipment to coexist in an environment that does not interfere with each other and is compatible with work. The electromagnetic compatibility of a modern electronic and electrical product (equipment, system) plays a vital role in ensuring the normal functioning of the product. This is a fact recognized by the industry at home and abroad.
In this paper, the causes and test methods of conducted interference are analyzed in combination with the national military standard electromagnetic interference test and the problems encountered in the experiment. The design of the power filter and the selection method of the filter in the electromagnetic compatibility design of the equipment are introduced. First, the causes of conducted interference are introduced.

1 Conducted interference In the electromagnetic compatibility test of a device, it was found that the conducted interference project CE102 exceeded the standard, and the test result is shown in Figure 1. The noise current on the product's power line is responsible for the conducted interference, because once these currents are transmitted to the power supply network, they will radiate effectively and cause interference. The coupling path of conducted interference is a directly connected circuit through which the interference signal is coupled to the sensitive device by the interference source. The solution to conductive coupling is to prevent the conductor from inducing noise by using appropriate shielding and separating the conductors, or by filtering to remove noise from the conductors before they enter the sensitive circuitry.

Figure 1 Test diagram of a device CE102

1. 1 Conducted interference from the device The path of the noise current entering the power supply network on the power line of the device under test is shown in Figure 2.

Figure 2 Noise chain generated in a device through the power line diagram (please read the PDF document for details)