Noise filter

A noise filter which reduces a common-mode voltage produced by a power converter that performs power conversion using switching operations of semiconductor elements, said noise filter comprising:

• a voltage detector that detects the common-mode voltage produced by the power converter;
• a voltage divider circuit that outputs a divided voltage divided from the common-mode voltage detected by the voltage detector;
• 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 a basis of the divided voltage;
• wherein the injection waveform generator generates as the output voltage, a voltage with which a difference between the superimposing voltage to be superimposed on each of the power lines and the common-mode voltage is within an allowable value.