1. Field of the invention
The invention relates to a method for controlling a power source comprising a first converter for converting an input voltage to an intermediate circuit voltage, an intermediate circuit capacitor and a second converter for converting the intermediate circuit voltage to an output voltage, whereby a process is controlled at the output of the second converter and in particular the output voltage and/or output current is controlled with the aid of the second converter.
The invention further relates to a process controller for a power source, which power source comprises a first converter for converting an input voltage to an intermediate circuit voltage, an intermediate circuit capacitor and a second converter for converting the intermediate circuit voltage to an output voltage. The controller comprises an input for the output voltage and/or output current, an output for activating the second converter and means for running a control algorithm, and the output voltage and/or output current is provided as a controlled variable and the second converter is provided as an actuator of a closed loop.
Finally, the invention relates to a power source, comprising a first converter for converting an input voltage to an intermediate circuit voltage, an intermediate circuit capacitor and a second converter for converting the intermediate circuit voltage to an output voltage and a controller of said type, the input of which for the output voltage and/or output current is connected to the output of the welding power source and the output of which is connected to the second converter for activating the second converter.
2. Description of the Related Art
Methods of controlling a power source of the type outlined above are known in principle. They are used to convert an input alternating voltage to an intermediate circuit voltage. Alternatively, another option is to convert an input direct voltage to an intermediate circuit voltage if the input direct voltage is not at the desired level. This intermediate circuit voltage is kept at a more or less constant level by means of an intermediate circuit capacitor. As a result, this intermediate circuit voltage is converted to an output voltage. The output voltage and/or output current are controlled by means of the second converter. For example, a pulse-shaped output current at constant voltage can be provided, such as needed for impulse welding, for example. Such methods are also used for charging batteries.
In this context, US 2010/225289 A1 discloses a two-stage voltage supply with a measuring circuit at its output and a controller connected to it, which activates the two switching stages of the voltage supply.
EP 0 866 284 A2 discloses an air conditioning system also having a two-stage voltage supply for the compressor. In an arrangement similar to that of US 2010/225289 A1, said voltage supply comprises a measuring circuit at its output and a controller connected to it, which activates the two switching stages of the voltage supply.
US 2011/309054 A1 also discloses a two-stage welding power source with a measuring circuit at the output and a process controller connected to it, which activates the first of the two switching stages.
US 2008/284388 A1 and JP 10 341572 A disclose other two-stage voltage supplies. These respectively comprise a measuring circuit at the output and on the intermediate circuit, which are connected to a controller, which activates the two switching stages of the voltage supply.