TDK recently announced a new line of filters designed expressly to filter the frequency converters for asynchronous motor controllers.
High frequency noise emissions from these frequency converters has become more of an issue as older motor technology is replaced with the newer variable speed – variable frequency motor controller systems. The EMI from these can cause interference up through the 2.4 GHz Wi0Fi ISM band. For example, there’s one rural high school in Colorado whose internet crashes every time a nearby water well pump turns on to water the corn field next door.
The high frequency harmonics are largely due to voltage overshoot because of the inductance in the wires to the motor. The TDK filters are designed to dampen this high dv/dt change, and so reduce the amount of EMI emitted.
