Performance of the position control of a permanent magnet sensorless drive

A sensor less position control of a permanent magnet motor has been implemented. The permanent magnet motor is made with interior magnets and concentrated windings. The 4-pole machine can produce 0.4 Nm of continuous torque and have a top speed of 2000 rpm. The peak torque is 0.8 Nm and the system DC-link voltage is 24 V. Sensorless control is utilised with signal injection during low speed operation and at higher speed the induced emf is used for tracking the rotor angle. The estimated rotor angle is used for positioning an ordinary FOC, (Field Oriented Control). The performance of the system is simulated, including FEM-calculated values of saturated flux in d- and q-axes. Cascaded regulators for the speed and the position make it possible to control the mechanical position of the machine. Tests on the real application show a position error of 30 electrical degrees. In this case it corresponds to +/- 15 degrees on the mechanical shaft.