emi filter frequency variable inductance circuit for pwm wave

Abstract

The invention provides an EMI filtering frequency-dependent inductive circuit used for PWM wave. The EMI filtering frequency-dependent inductive circuit is characterized by comprising a current sensor, a low-pass filter circuit, an amplitude-phase conditioning circuit, a power amplification circuit, a frequency-dependent inductor which consists of a compensating winding and a filtering winding that share the same magnetic core, a PWM power supply and a load, wherein the input end of the current sensor is connected with the output end of the filtering winding; the output end of the current sensor is connected with the input end of the low-pass filtering circuit; the output end of the low-pass filtering circuit is connected with the input end of the amplitude-phase conditioning circuit; the first output end of the amplitude-phase conditioning circuit is connected with the input end of the power amplification circuit; the second output end of the amplitude-phase conditioning circuit passes through an adjusting resistor to be grounded; the filtering winding is connected with the PWM wave power supply and the load in series; and the output end of the power amplification circuit passes through the compensating winding and the adjusting resistor to be grounded. The EMI filtering frequency-dependent inductive circuit aims to realize EMI filtering of the PWM wave.

Description

technical field [0001] The invention relates to a frequency-variable inductance filtering technology based on the principle of magnetic flux compensation, in particular to an EMI filter frequency-variable inductance circuit for PWM waves. Background technique [0002] Filtering technology is always a core technology in power electronic converter systems, and the occurrence of switching frequency and its harmonics cannot be avoided in the process of power conversion. Taking the inverter technology as an example, the PWM wave contains not only the power frequency component of the fundamental wave, but also the switching frequency and its harmonic interference components generated by power electronic devices; its original waveform is basically in the form of a square wave, containing a wide spectrum component , the LC filter circuit composed of inductors and capacitors will produce resonance problems, which will pose a hazard to filter devices and equipment. If the filter circ...

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Problems solved by technology

[0004] Due to the limited switching frequency of high-power power electronic converter devices, to realize the sine of the PWM wave, that is, to filter the switching frequency and its harmonics to the greatest extent, while not reducing the fundamental power frequency voltage of the load, only a simple series connection is used. Inductive filters cannot achieve

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