METHODS OF STARTING AN INVERTER SYSTEM, AND INVERTER SYSTEMS

An inverter system (1) is described. The inverter system (1) includes a DC power source such as a plurality of photovoltaic (PV) panels (8), an inverter (2) and a controller (32). The inverter (2) includes a plurality of semiconductor devices (e.g., controllable semiconductor switches such as IGBTs and anti-parallel connected diodes) arranged in a suitable inverter topology. The inverter (2) includes DC input terminals (4) connected to the PV panels (8) by means of a DC link (10) and at least one AC output terminal (6). When starting the inverter (2), the controller (32) is configured to enable a short circuit state of the inverter (2) by controlling the semiconductor switches to create a short circuit between the DC input terminals (4) such that the inverter (2) carries a current substantially equal to the short circuit current of the PV panels (8). This short circuit current may be used to pre-heat the semiconductor devices of the inverter (2) to reduce failure rates caused by cosmic radiation when the semiconductor devices subsequently experience high blocking voltages during normal operation of the inverter.