Fuji Electric Co., Ltd.

Tetsuhiro Morimoto

Tatsuhiko Fujihira

Kazuhiko Yoshida

Shoichi Furuhata

Kazunori Oyabe

Yukio Yano

Shin Kiuchi

A combined semiconductor rectifying device includes PN-junction silicon diode and Schottky barrier diode exhibiting a breakdown voltage higher than the breakdown voltage of PN-junction silicon diode, and Schottky barrier diode is made of a semiconductor, the band gap thereof is wider than the band gap of silicon. The combined semiconductor rectifying device exhibits a shortened reverse recovery time, low reverse leakage current characteristics and a high breakdown voltage, and is used advantageously in an electric power converter.

Combined semiconductor rectifying device and the electric power converter using the same

The disclosed invention is designed to prevent the oscillation which often occurs in an over-current protection apparatus for an insulated gate controlled transistor. The apparatus improves the response in current detection, to prevent oscillation, and improves protection speed against over-current. This is accomplished by separating the gates of the main transistor and the current detector transistor; by setting a shorter time constant for the gate circuit of the current detector transistor than that of the gate circuit of the main transistor; by feeding the detection signal obtained from the current detecting means which detects the current i of the current detector transistor proportional to the current I flowing through the main transistor, to the control means; and by controlling the gate potentials of both transistors to protect the main transistor from the over-current by feeding the comparison output Sd from the comparator circuit, which compares the voltage of the signal Vd with the reference voltage Vr, to the control circuit.

Over-current protection apparatus for transistor

Growing community of inventors

Azumino, Japan

Tetsuhiro Morimoto