| 摘要 |
PURPOSE:To reduce a noise at the time of switching and a switching loss, by driving so as to reduce a time variation rate dV/dT of voltage between main electrodes in case of switching a semicondutor element, in a gate driving circuit consisting of a semiconductor element. CONSTITUTION:When a transistor TR55 of a gate circuit 5 consisting of an MOSFET3 is changed to off-state from on-state, voltage of opposite polarity is induced to the winding of a transformer 59 by energy accumulated in excitation inductance of the transformer 59, input capacity Ciss of the FET3 is charged through a diode 57, the FET3 is turned on, and supresses dV/dT between the main electodes of the FET3 in this case. When the FET3 is turned off, voltage is induced to winding n2 by turning on the TR55, and a current is flowed in the direction for charging the charged Ciss in reverse. A discharge time of the Ciss is controlled by a resistance 58 and output voltage of the winding n2, and dV/dT in case of turning off the FET3 is reduced. In this way, a noise caused by spike voltage in case of switching the FET3 is reduced, and the switching loss is also reduced. |
