Online extraction method for common mode impedance of common mode chokes

Abstract

The invention discloses an online extraction method for common mode impedance of common mode chokes. According to the invention, common mode voltage and common mode current of the common mode chokes are measured through an oscilloscope spectrum channel, and spectrum characteristics of the common mode impedance of the common mode chokes are acquired by using a method of spectrum division of the common mode voltage and the common mode current. Compared with a traditional method of extracting impedance parameter through an electromagnetic numerical calculation method and a network impedance analyzer, the online extraction method disclosed by the invention does not need to build a simulation model through software, thereby being simpler and more convenient in the process, and being easy to implement. Compared with the traditional method that characteristics of the common mode chokes in actual operation cannot be reflected in the impedance extracting process, the common mode impedance extraction method disclosed by the invention performs measurement when the system operates, thereby being capable of more accurately reflecting characteristics showed in practical applications of the common mode chokes, and having better guidance significance for suppressing electromagnetic interference in the system.

Description

technical field [0001] The invention belongs to the technical field of power electronics electromagnetic compatibility testing, and in particular relates to an online extraction method for common-mode impedance of a common-mode choke coil. Background technique [0002] The frequency converter has excellent speed regulation performance and remarkable energy-saving effect, and is widely used in metallurgy, machinery, petroleum, transportation and other fields, and has produced significant economic benefits. However, because the switching devices inside the frequency converter are in a high-speed switching state, the frequency converter has serious electromagnetic interference (EMI) problems, which affect the safe and stable operation of the frequency conversion drive system, and also pose threats to adjacent equipment and power supply networks. [0003] The pulse width modulation technology will cause the three-phase asymmetry of the voltage on the output side of the inverter,...

AI Technical Summary

Problems solved by technology

The main electromagnetic numerical calculation methods are finite element method, finite integral method, finite difference method, method of moments, etc. However, when using numerical calculation methods to extract impedance parameters, it is necessary to establish a simulation model through software, and the accurate physical structure must be known. The calculation is complex and Long simulation time, not universal

The network impedance test method is a relatively common impedance extraction method at present, which requires a lot of calculation and approximate processing, and the impedance analyzer is expensive

In addition, the above two types of methods are all off-line, and cannot reflect the characteristics of the common mode choke coil when it is actually working.

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