Method for open-loop/closed-loop control of at least two parallel

Abstract

In a method for open-loop/closed-loop control of current converter valves of at least two load-guided parallel oscillating circuit inverters being supplied from a common direct current or direct voltage source and being connected in series on the DC side, each inverter has one induction furnace with a compensating conductor. Two diagonally opposed current converter valves are ignited at a time in one inverter to establish a flow of current from the source with a series-connected choke through the parallel oscillating circuit connected to that inverter. Load phase angles of the parallel oscillating circuit inverters are adjusted, resulting in arbitrarily specified individual powers of the parallel oscillating circuits wherein a maximum power that can be output by the source is taken into account, and attaining a specified ratio between the individual powers of the parallel oscillating circuits. An intervention is made into the open-loop/closed-loop control of the source only after one of the load phase angles to be established reaches a minimum value being dictating in particular by valve hold-off intervals, for reducing the direct current or direct voltage, while operating the source in fully driven fashion at load phase angles to be established above the minimum value.