Patent ID: 7800336
Filing Date: 2010-09-21
Classification: H02P

Abstract:
1. A control system for a synchronous electric motor which includes a stator and a moving element, the stator including a plurality of stator magnetic poles each polarized when a current is flown through armature winding, the moving element including a plurality of moving element magnetic poles, the control system comprising: a position detecting section for detecting a relative magnetic pole position θm of the moving element magnetic pole relative to the stator magnetic pole, and outputting a relative position detection signal indicating the relative magnetic pole position θm; a torque command generating section for generating a torque command; a current command generating section for generating a current command that determines a current to be flown through the armature winding based on the torque command; a current control device that supplies the current to the armature winding based on the current command; a current feedback section for detecting the current flowing through the armature winding, and generating a feedback current signal indicating the current; the current feedback section and the current control device being configured to determine a phase of the current, based on the relative magnetic pole position θm detected by the position detecting section; an acceleration computing section for computing an acceleration of the moving element based on the relative magnetic pole position θm output from the position detecting section; an added torque generating section for generating an added torque TADD to be added to the torque command and necessary for allowing the moving element to overcome friction toque and thereby move; an initial correction generating section for generating, during an initial operation, a magnetic pole position correction θc to be added to the relative magnetic pole position θm so as to shift the phase of the current substantially to a phase where the maximum torque may be obtained, when an absolute value of the acceleration is smaller than a predetermined reference value; and a regular correction generating section for generating, during a regular operation, the magnetic pole position correction θc to be added to the relative magnetic pole position θm so as to shift the phase of the current substantially to the phase where the maximum torque may be obtained, when the absolute value of the acceleration is equal to or larger than the predetermined value; the initial correction generating section being configured to generate the magnetic pole position correction θc during the initial operation by adding 90° to and/or subtracting 90° from an initial value of a basic correction θ the regular correction generating section including: