Commission E (Electromagnetic Noise and Interference)

Activity Report (December 2006 - March 2007)


March 08, 2007

Osamu Fujiwara



2. Technical Trends

Transient current suppresser using MOSFET device

Large transient current by the electromagnetic induction causes malfunctions of electrical systems. EMI filters using inductors and capacitors have been developed to suppress the current. However, large inductors and capacitors are needed to compose the filter because the cut-off frequency of the filter is relatively low. A new type suppresser using the MOSFET device has been developed. When the electrical appliance is in the state of turning off, the MOSFET is also in the state of turning off, and when the appliance enters the state of turning on, the MOSFET enters the state of turning on, too. However, the speed turning on of the MOSFET is later than the speed of the appliance. As a result, the generation of the high voltage is suppressed because the level of the induction voltage is in proportion with the transient speed. The report says the suppressor can reduce the transient current to 1/100. This also says that the size and the price can be also reduced because the inductor does not need in this suppressor. ( Nobuo Kuwabara )