Methods and apparatus for simultaneous operation of a variable-frequency drive (VFD) and a controller. The VFD drives an electric motor of a drilling rig machine. The controller controls temperature of an insulated-gate bipolar transistor device (IGBT) of the VFD by controlling an air mover in response to real-time temperature data. The air mover generates airflow into a passage, the airflow thereby interacting with radiating members extending into the passage from a heat sink thermally coupled with the IGBT in the inner housing outside the passage.