Patent ID: 7498545
Filing Date: 2009-03-03
Classification: F04B,F04C,H02P

Abstract:
1. A controller for an electric motor in an electric compressor, the compressor including a rotary shaft that is rotated by the electric motor and a compressing member that, based on rotation of the rotary shaft, compresses and discharges refrigerant in a compression chamber, a coil of the electric motor being cooled by the refrigerant, the controller controlling a current supplied to the coil within a range less than or equal to a predetermined maximum value, the controller comprising: a temperature detection section detecting either a temperature of the coil or a temperature about the coil prior to activation of the electric motor; and a limiting section, wherein, when a detection temperature that is detected by the temperature detection section prior to activation of the electric motor reaches a predetermined first reference temperature, the limiting section executes a limiting control to limit an upper limit value of the current supplied to the coil to a limiting value that is less than the maximum value, wherein the limiting section cancels the limiting control after a reference time set in advance has elapsed since the start of the limiting control, wherein the temperature detection section continues detecting either the temperature of the coil or the temperature about the coil after the limiting control is cancelled, and wherein, if the detection temperature after the cancellation of the limiting control surpasses a second reference temperature set in advance, the limiting section executes the limiting control until the detection temperature becomes equal to the second reference temperature.