Patent ID: 6960898

Claim:
A control unit for controlling a permanent-magnet-type synchronous motor incorporating a position sensor, the motor being connected to a power converter, comprising: a motor speed unit for determining the rotational speed of said motor based on a signal output from said position sensor; a motor position unit for determining a magnetic polar position of said motor based on the signal output from said position sensor; a position-sensor abnormality identifier means for detecting abnormalities in the signal output from said position sensor; a first controlling means for generating voltage-instructing values for said power converter by utilizing the magnetic polar position determined by the motor position unit so as to cause a motor speed detection value detected by said motor speed unit to pursue a speed instruction value; a second controlling means for generating voltage-instructing values having a magnitude and a phase corresponding to said speed instruction value by employing a magnetic polar position based on a frequency corresponding to said speed instruction value; and a switching means for selecting either said first controlling means or said second controlling means so as to transmit voltage-instructing values generated by either of said controlling means to said power converter, wherein, when said position-sensor abnormality identifier detects that the signal output from said position sensor is normal, said switching means transmits voltage-instructing values from said first controlling means to said power converter and when said position-sensor abnormality identifier detects that the signal output from said position sensor is abnormal, said switching means transmits voltage-instructing values from said second controlling means to said power converter.