Sensorless torque control of salient-pole synchronous motor at zero-speed operation

A position and speed sensorless control using the counter electromotive for ce of permanent-magnet motor (PM) debases the control performance at a low speed. We will propose a controllable system at full speed, including a zer o speed using saliency. At low speed, the sensorless control is made by observing a current ripple at a time when alternating voltage has been applied to a salient-pole motor . Also, for discriminating the S and N poles of the magnet, magnetic satura tion is used. A device has been applied to the motor rotor to allow the mag netic saturation to come about easily, Furthermore, at a time of high speed, drive at a full-speed range has been accomplished by switching smoothly over to a sensorless driving system maki ng use of counter electromotive force. All algorithms are implemented by so ftware, and this system can operate successively from starting to high-spee d operation, Shown herein are the operational principles at a low speed, analysis and ex perimental results, the control scheme, how to changeover the control mode at a high speed, and the experimental results.