Sensorless Current and Speed Control of a PMSM Driven with a $\Delta\Sigma$-PWM

In this paper two novel methods for sensorless angle detection, implemented in delta sigma signal processing, are shown. They are both based on an estimation of the electromagnetic force (EMF) in combination with a phase locked loop. The advantage of these combinations, unlike the common implementation with the arctangent function, is the possibility to perform the calculations in DSSP with a sampling rate of 10 MHz. Thus the input signals are ΔΣ bit-streams, which even are intermediate results in the control system and the observed angle is updated with 10 MHz. One sensorless angle detection method is based on the set voltage output by a proportional phase current controller, the other is based on the current control error. The experiments result in fast locking times (80 ms and 180 ms from stand still) and an average angle accuracy of 0.2° and 0.6°. In both performance indicators the angle detection based on the current control error shows better performance.