| 摘要 |
PCT No. PCT/SE87/00581 Sec. 371 Date Jul. 20, 1989 Sec. 102(e) Date Jul. 20, 1989 PCT Filed Oct. 8, 1987 PCT Pub. No. WO88/04491 PCT Pub. Date Jun. 16, 1988.A method and device for controlling a bridge circuit for providing current or power to a load. The bridge comprises two transistors including flywheel diodes and connected in series between positive and negative power supply rails for conducting current to or from the load under control of a control drive circuit. An LC-circuit is connected between the bridge circuit and the load. The bridge voltage (E) of the connection between the two transistors and the current (I) through the inductance of the LC-circuit are monitored and a firing pulse is supplied to one of the transistors. When the current (I) through the inductance exceeds a preset value (I'), the transistors is turned OFF, whereupon the current of the inductance continues to flow another way through the flywheel diode of the opposite semiconductor member and consequently the bridge voltage (E) changes polarity a first time to the opposite rail polarity until the magnetic energy of the inductance has been terminated resulting in a second change of polarity of the bridge voltage (E) towards the first rail polarity. The change of the polarity of the bridge voltage (E) towards the first rail polarity is detected and another firing pulse is supplied at or shortly after said change. |
