A power converter system is described. The system includes a power converter with a first converter including a plurality of semiconductor devices. Each semiconductor device includes at least a controllable semiconductor switch having a threshold voltage and a gate voltage for normal on-state conduction. The first converter has first and second DC terminals connected to a DC circuit, and a plurality of AC terminals. A controller is configured to supply current to the first converter (e.g., from an AC power source) and enable a short circuit state of the first converter by controlling semiconductor switches of the first converter to create at least one short circuit path through the first converter that carries the supplied current. At least one of the semiconductor switches in at least one of the short circuit paths is operated with modified on-state conduction in order to increase conduction losses. A gate driver applies to the semiconductor switch a modified gate voltage that is less than the gate voltage for normal on-state conduction.