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Device and method for measuring internal impedance of noise source of switch power supply EMI

A technology of switching power supply and measuring device, which is applied in the direction of measuring device, power supply test, measuring resistance/reactance/impedance, etc. It can solve the problems of ignoring the internal impedance of the noise source, not knowing the internal interference source and impedance of the noise source, etc., and achieve electromagnetic interference suppression , Simple operation, high precision effect

Inactive Publication Date: 2008-10-22
NANJING NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] EMI filter is an effective measure to suppress electromagnetic interference, but at present, when designing EMI filters at home and abroad, the internal interference source and impedance of the noise source are not known in advance, and the internal impedance of the noise source is often ignored during design. General EMI Filter Design

Method used

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  • Device and method for measuring internal impedance of noise source of switch power supply EMI
  • Device and method for measuring internal impedance of noise source of switch power supply EMI
  • Device and method for measuring internal impedance of noise source of switch power supply EMI

Examples

Experimental program
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Effect test

Embodiment 1

[0024] Such as figure 1 and 2 As shown, the internal impedance measurement device of the EMI noise source of the switching power supply is composed of a line impedance stabilization network (LISN), a common mode impedance test module, a switching power supply (SMPS) and a load, a signal generator and a spectrum analyzer. The power line from the power grid is directly input into the line impedance stabilization network (LISN), passes through the common mode impedance measurement module, and then is input into the switching power supply and load to form a whole power loop. The signal generator provides an input signal for the common mode impedance test module, and then the response signal in the module is detected by the spectrum analyzer.

[0025] The common mode impedance test module consists of a pair of 16mH common mode choke coils, two 1uF capacitors and two current probes, one of which is an injection current probe, choose Tektronix CT2, and one is a detection current pro...

Embodiment 2

[0029] Such as figure 1 and 3 As shown, the internal impedance measurement device of the EMI noise source of the switching power supply is composed of a line impedance stabilization network (LISN), a differential mode impedance test module, a switching power supply (SMPS) and a load, a signal generator and a spectrum analyzer. The power line from the power grid is directly input to the line impedance stabilization network (the line impedance stabilization network adopts an international standard structure), passes through the differential mode impedance measurement module, and then is input to the switching power supply and load to form a whole power supply circuit. The signal generator provides an input signal for the common mode impedance test module, and then the response signal in the module is detected by the spectrum analyzer.

[0030]The differential mode impedance test module consists of two 350uH differential mode choke coils, two 1uF capacitors and two current probe...

Embodiment 3

[0032] Taking the Keri switching power supply as an example, the test is carried out. The experimental device is as follows: figure 1 As shown, the test is carried out when the circuit is connected to the standard impedance, short circuit and normal operation of the switching power supply. For the test of the internal impedance of the noise source of the switching power supply, it is mainly divided into common mode and differential mode. The impedance test modules are different, and the test methods and steps are the same.

[0033] Step 1: First remove the SMPS from the main circuit, short the L and N wires, and connect a fixed impedance R std (Generally take 500Ω), one end of the impedance is connected to the short-circuit point of the L and N wires, and the other end is connected to the E wire. The neutral line impedance stabilization network of the main circuit is not energized, adjust the output frequency of the signal generator, take several points within the range of 10...

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Abstract

The invention discloses a measuring device of switch power supply EMI noise source internal impedance that comprises line impedance stabilization network, common mode / differential mode impedance test module, signal generator and spectrum analyzer; power cord is directly input to the line impedance stabilization network, passes the common mode / differential mode impedance test module, and then input to the switch power supply and load to construct a whole power circuit; the signal generator provides a input signal for the common mode / differential mode impedance test module, response signal in the module is detected by the spectrum analyzer. The measuring method of switch power supply EMI noise source internal impedance IA also disclosed. The measuring device and method can measure the all-purpose internal impedance for all kinds of noise source, but also measure the unknown impedance, the accuracy is high and the operation is simple. The measuring method can judge the nature of internal impedance and provide a precondition for designing of EMI filter that is the designing of filter fulfills the impedance matching property of filter.

Description

technical field [0001] The present invention relates to a device and a measurement method for measuring the internal impedance of a conductive electromagnetic interference (EMI) noise source, which provides a premise basis for the suppression of conductive EMI noise, that is, the design of an EMI filter, and belongs to the field of electromagnetic compatibility equipment design and technology field. Background technique [0002] EMI filter is an effective measure to suppress electromagnetic interference, but at present, when designing EMI filters at home and abroad, the internal interference source and impedance of the noise source are not known in advance, and the internal impedance of the noise source is often ignored during design. General purpose EMI filter design. Since the internal impedance of each noise source is not the same, and the matching relationship between the interference source impedance and the filter impedance directly affects the filtering effect of the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R27/00G01R27/28G01R31/40
Inventor 赵阳沈雪梅李世锦黄学军顾洲房义军尹海平孙焱
Owner NANJING NORMAL UNIVERSITY
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