INDEPENDENT VOLTAGE INVERTER

The inverter is used in frequency controled electric drives. It preserves the reswitching capacity when the power DC voltage is changed and the switching losses at high frequencies are reduced. The inverter, in each of its arms, has two power and two extinction thyristors. The anodes of the first extinction thyristors from all arms of the inverter are connected to a general point and between it and the positive supply bus, a catching diode is connected in forward direction. The cathodes of the second extinction thyristors from all arms of the inverter are also connected to a general point, and between it and the negative supply bus a second catching diode is connected in forward direction. A first source of further charging is connected between the cathode of the first catching diode and the negative supply bus, and a second source of further charging - between the anode of the second catching diode and the positive supply bus. The invertor is used in frequency adjustable electric drives. It retains the switching capacity during changes of the voltage. It reduces switching losses at high frequencies. In each arm, the invertor contains two power and two quenching thyristors. The anodes of the first quenching thyristors of all invertor arms are connected in a shared point and between it and the plus supply bus is switched a directly biased cut-off diodes. The cathodes of the two quenching thyristors of all invertor arms are also connected in a shared point, while between it and the minus supply bus a second cut-off diode is switched in direct bias. Between the cathode of the first cut-off diode and the minus charging bus, a first source of topping charge is positioned, while between the anode of the second cut-off diode and the plus power supply bus is switched a second source of topping charge.