US Patent 9404811 Motor housing thermal sensing

A motor driven compressor apparatus includes a first stage compressor, a second stage compressor, an electric motor disposed between and coupled to the first stage compressor and the second stage compressor, thermal sensors disposed on the electric motor and configured to externally measure internal temperatures of the electric motor or internal bearings or components, and an external controller coupled to the electric motor and to the thermal sensors, and configured to at least one of slow down a speed of the electric motor and shut down the electric motor in response to at least one of an excess of a predetermined internal temperature and a rate of internal temperature change.