Abstract: A current detector includes a chopper circuit composed of a switching circuit, i.e. an inverse-parallel circuit composed of an insulated gate bipolar transistor IGBT and a diode, and a switching circuit, i.e. an inverse-parallel circuit composed of an IGBT and a diode, which are connected in series. When the diode on the opposite arm is turned on, a reverse recovery current is detected and its output is directed to a gate drive circuit via an insulating circuit. A switch in the gate drive circuit is opened to increase resistance, in order to reduce the speed at which the gate of the switching device is charged. Thus, the surge voltage and its increase ratio are reduced without reducing a switching speed or requiring a snubber circuit.

Abstract: A balancing circuit balances the steady-state currents of the switching devices in an electric power converter, which facilitates reducing the size of the power converter and precisely balancing the steady-state currents. The balancing circuit holds transient sensing voltages at the time of turning-on of the switching devices, and detects the unbalance between the currents of the switching devices based on the distribution or unbalance of the sensing voltages by comparing the steady-state sensing voltages or the values corresponding to the steady-state sensing voltages with the stored transient sensing voltages. The steady-state currents of the switching devices are balanced by regulating the drive voltages of the switching devices based on the detected distribution of the steady-state currents.

Abstract: In packaged bridge circuit modules with power switching transistors such as IGBT's, internal wiring inductance can cause switching voltage spikes and imbalance between switching transistors. Upon inclusion of suitably arranged and configured inductance elements, internal wiring inductance can produce a counter-electromotive force during switching. To this end, an internal connecting terminal may branch from an output terminal, a bridge-shaped internal connecting terminal may be connected between an emitter circuit pattern of one power transistor and a collector circuit pattern of another power transistor, or signal terminals as auxiliary emitter terminals of two power transistors may be connected to an inductance providing region in a current path of an emitter circuit pattern.

Abstract: In a switching transistor control circuit, the switching transistor has a control electrode and first and second main circuit electrodes. A reactor is connected in series with the first main circuit electrode of the switching transistor to receive a main circuit current through the switching transistor. Circuitry is connected to an end of the reactor remote from the first main electrode and to the control electrode of the switching transistor, for supplying an electromotive force to the control electrode which is generated by the reactor as main circuit current decreases when the switching transistor is turned off. A control electrode driving circuit is connected to the control electrode, and is connected to one of the first main circuit electrode and a predetermined intermediate position on the reactor, for supplying a drive signal to the control electrode for selectively turning the switching transistor on and off.