Manipulation of resonant elements in switching power supplies
A system to generate weld power for a welding process comprises: a power supply including a power inverter having multiple switches controlled by multiple switching signals such that each switch is alternately turned ON and OFF within each switching cycle of one of the multiple switching signals, to supply a current to an output circuit of the power supply that is configured to convert the current to the weld power, wherein the power inverter includes a capacitor and a capacitor switch connected in series with each other and across a switch of the multiple switches; and a controller to monitor a weld parameter and control the capacitor switch to either connect the capacitor across, or disconnect the capacitor from, the switch continuously across multiple cycles of a respective one of the multiple switching signals, depending on whether the weld parameter meets a predetermined operating condition of the welding process.
1 . A system to generate weld power for a welding process, comprising:
a power supply including a power inverter having multiple switches to be controlled by respective ones of multiple switching signals such that each switch is alternately turned ON and OFF within each switching cycle of a respective one of the multiple switching signals, to supply a current to an output circuit of the power supply that is configured to convert the current to the weld power, wherein the power inverter includes a capacitor and a capacitor switch connected in series with each other and across a particular switch of the multiple switches; and
a controller to monitor a weld parameter and control the capacitor switch to either connect the capacitor across, or disconnect the capacitor from, the switch continuously across multiple cycles of a respective one of the multiple switching signals, depending on whether the weld parameter meets a predetermined operating condition of the welding process.
2 . The system of claim 1 , wherein:
the output circuit includes a transformer coupled to the multiple switches; and
the capacitor and an inductance of the transformer form a resonant circuit for zero voltage switching (ZVS) of the particular switch.
3 . The system of claim 2 , wherein:
the output circuit further includes an inductor that is external to the transformer to form the resonant circuit.
4 . The system of claim 1 , wherein the weld parameter is indicative of the weld power and the controller is configured to:
when the weld parameter indicates that the weld power is in a first range, control the capacitor switch to connect the capacitor across the particular switch; and
when the weld parameter indicates that the weld power is not in the first range, control the capacitor switch to disconnect the capacitor from the particular switch.
5 . The system of claim 1 , wherein the weld parameter is indicative of a welding stage of the welding process and the controller is configured to:
when the welding stage is a predetermined welding stage, control the capacitor switch to connect the capacitor across the particular switch; and
when the welding stage is not the predetermined welding stage, control the capacitor switch to disconnect the capacitor from the particular switch.
6 . The system of claim 1 , wherein:
the power inverter further includes multiple capacitors connected in series with corresponding ones of multiple capacitor switches and across corresponding ones of the multiple switches; and
the controller is configured to control each capacitor switch independently to connect each capacitor across, or disconnect each capacitor from, each switch continuously across the multiple cycles of each switching signal, depending on whether the weld parameter meets the predetermined operating condition of the welding process.
7 . The system of claim 1 , wherein:
the power inverter includes series-connected first and second switches connected from a first voltage rail to a second voltage rail, and to each other at a first node, and the capacitor and the capacitor switch are connected in series from the first node to a voltage rail of the first voltage rail or the second voltage rail.
8 . The system of claim 7 , wherein:
the capacitor is connected to the first node and the capacitor switch, and the capacitor switch is connected to the voltage rail.
9 . The system of claim 7 , wherein:
the capacitor is connected to the voltage rail and the capacitor switch, and the capacitor switch is connected to the first node.