Surge suppressor

Japanese researchers at OKI Electric Cable and Tokyo Metropolitan University have developed a new method to suppress micro-surge, an over-voltage noise that occurs when an inverter switches an AC waveform into a series of digital pulses. 

Conventionally, an LC filter circuit inserted between the inverter and motor drive-wire slowed down the rise time on the signal waveform to the motor and dissipated the surge energy as heat.

However, with this technique, as the motor power increased, it was necessary to use expensive and large-sized high-power rated capacitors and coils for the task.

Now, however, the researchers at OKI Electric Cable claim that their new supression technology – based on the use of surge-suppression cable and energy regeneration techniques – is significantly smaller in size, and less expensive than conventional filters.

In use, only the surge energy from the driver pulse train to the motor is returned to the inverter via an energy regeneration module that comprises delay circuitry and a rectifier.