Circuit assembly and method for generating alternating current from at least one power supply units with output DC voltage which varies over time

The circuit arrangement comprises one or multiple parallel connected partial circuit arrangement (1) for power supply to an inverter circuit (9) which is connected with a power network (90). A supply line is provided between a capacitor (30) and a connection (42). A direct current source (6) is provided for supplying a control circuit (7) for controlling of synchronous converter (4). An independent claim is also included for a method for controlling a circuit arrangement.