Mitsubishi Electric Corporation

Mitsubishi Electric Engineering Company, Limited

Yasuaki Furusho

Yuki Fujita

Hiroyuki Ichinose

Ryota Asakura

Ryosuke Kobayashi

Mamoru Kamikura

A noise filter includes: a voltage detector that detects a common-mode voltage; a voltage divider circuit that outputs a divided voltage divided from the common-mode voltage; multiple common-mode transformers that are connected separately to respective power lines of multiline systems connected in parallel relation to each other to an input or output of the power converter, and that superimpose a superimposing voltage having an opposite polarity to the common-mode voltage on each of the power lines of multiline systems; and an injection waveform generator that generates at least one output voltage to be outputted to primary sides of the multiple common-mode transformers, on the basis of the divided voltage. The injection waveform generator generates as the output voltage, a voltage with which a difference between the superimposing voltage to be super-imposed on each of the power lines and the common-mode voltage is within an allowable value.

Noise filter

A noise filter includes: a voltage detector which detects a common mode voltage generated by a power converter; a voltage division circuit which outputs a division voltage obtained by dividing the common mode voltage detected by the voltage detector; a plurality of common mode transformers which superimpose injection voltages each having a polarity opposite to a polarity of the common mode voltage onto an output from or an input to the power converter; and an injection waveform generator which generates, on the basis of the division voltage, output voltages to be outputted to primary sides of the plurality of common mode transformers. The injection waveform generator generates the output voltages such that a difference between the common mode voltage and a total injection voltage obtained by summing the injection voltages to be superimposed by the plurality of common mode transformers is equal to or smaller than an allowable value.

Provided is a low-cost noise filter having a noise suppression effect that is not reduced even when a resonance frequency changes according to changes in temperature. A noise filter includes: a noise detection unit which detects a common mode noise; a cancellation signal output unit; an injection unit which injects a cancellation signal; and a grounded capacitor. The cancellation signal output unit includes a filter part which generates the cancellation signal from the common mode noise, and an amplification part which amplifies the cancellation signal. A temperature dependence of a product of an inductance value and a capacitance value of a main circuit portion including the noise detection unit, the injection unit, and the grounded capacitor, and a temperature dependence of a product of an inductance value and a capacitance value of the filter part, are equal to each other.

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Tokyo, Japan

Yasuaki Furusho