Ethernet power supply equipment and method for suppressing electromagnetic radiation

Abstract

The invention discloses Ethernet power supply equipment and a method for suppressing electromagnetic radiation. The Ethernet power supply equipment comprises a POE (Power Over Ethernet) power source, an electromagnetic radiation suppressing circuit, an Ethernet transformer and an Ethernet interface; the electromagnetic radiation suppressing circuit comprises a primary filter, a secondary filter and a third filter; the primary filter receives current from the POE power source, filters common-mode interference and high-frequency differential mode interference out of the current and transmits the current to the secondary filter; the secondary filter receives the current from the primary filter, filters low-frequency differential mode interference out of the current and transmits the current to the third filter; the third filter receives the current from the secondary filter, filters out the differential mode interference of the positive pole of the POE power source to the protection ground and the differential mode interference of the negative pole of the POE power source to the protection ground and transmits the current to the center tap of the Ethernet transformer. The proposal provided by the invention is capable of effectively reducing the electromagnetic radiation quantity introduced by the POE power source.

Description

technical field [0001] The invention relates to Ethernet power supply equipment (PSE, Power Sourcing Equipment), in particular to a PSE and a method for suppressing electromagnetic radiation. Background technique [0002] Power over Ethernet (POE, Power Over Ethernet) refers to providing 48V DC power to terminal devices through Ethernet cables. see figure 1 , is a schematic structural diagram of a POE system in the prior art, the system includes a PSE and a powered device (PD, Powered Device), and the PSE includes a POE power supply, an electromagnetic radiation suppression circuit, an Ethernet transformer and an Ethernet interface. Ethernet PSEs are generally switches, routers, transport network equipment, etc., while PDs are generally network cameras, laptops, etc. The PSE is equipped with an electromagnetic radiation suppression circuit with POE function. The POE power supply transmits the current to the Ethernet transformer through the electromagnetic radiation suppres...

AI Technical Summary

Problems solved by technology

[0006] (1) The noise of the public power grid is introduced into the PSE through the POE power supply to cause interference, which will increase the EMI radiation of the Ethernet line, which will cause the EMI test to fail

[0007] (2) The POE power supply is generally a switching power supply, and its switching noise will interfere with the Ethernet differential signal. During the EMI test, it will have a negative impact on the template test of the Ethernet line signal, which will cause the EMI test to fail.

The inventor found in practice that although the RC filter circuit is used for filtering, although it has a certain inhibitory effect on the common-mode interference in the current, it also has the following disadvantages: First, as the power of the POE power supply continues to increase, the existing RC filter The circuit has a limited effect on electromagnetic radiation suppression and cannot effectively filter out interference; secondly, the RC filter circuit easily introduces external surges into the PSE and affects the internal circuit

[0009] In summary, the existing PSE cannot effectively reduce the radiation of POE power supply

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