| 摘要 |
PURPOSE:To obtain a stable drive characteristic efficiently at high speed by providing a switch element for current feedback polarity selection giving selectively positive/negative current feedback having the quantity in response to a main current flowing to a main semiconductor switching element to a drive circuit. CONSTITUTION:A transformer 8 constitutes a current feedback means to a main semiconductor switching element (transistor Tr1). A winding Nb constitutes a closed loop together with a winding N3 of a drive transformer 3, a diode 9 and a switch element switch S1 controlled switchingly with an external control signal. A circuit 11 consisting of a discharge element is connected in parallel with the winding Nb, and the windings Nb and N1 are connected together via a diode 10, constituting positive and negative feedback paths in a way sharing the winding Nb in common. Since a reverse base current and a forward base current having a value in response to the quantity of the main current flowing to the Tr1 are given, stable high speed switching operation independently of the quantity of the main current is attained. |
