Rectifier and Inverter Operation

Rectifier and Inverter Operation

Since valves conduct in only one direction, the current in a converter cannot be reversed. A reversal of Ud results in a reversal of power. An alternating voltage must exist on a primary side of the transformer for inverter operation. The direct voltage of the inverter opposes the current as in a dc motor and is called a back voltage. The applied direct voltage from the rectifier forces current through the inverter valves against the back voltage. When α is greater than 90º inverter operation can be achieved. However, common practice is to use ignition advance angle β and extinction advance angle γ for describing inverter performance.