A Sensorless PMSM Fundamental Mode Controller with High Dynamic Full Range Speed Control

Previous methods of sensorless vector control of the PMSM operate by indirectly determining the rotor position usually from the back EMF or from saliency detection using HF injection. This paper introduces an entirely new method of sensorless control of the PMSM where instead of trying to determine the rotor position, the basic torque loop structure is rearranged to remove the need for position information allowing fundamental mode sensorless operation at zero speed. As a bonus, the new structure allows the use of a low bandwidth linear current controller for the control of torque, provides instantaneous response (within one sample period) to changes in the command torque and makes available instantaneous values of speed and position at all speeds including zero for use by outer speed and position feedback loops. Combined with an outer speed loop controller, it allows speed control of high dynamic performance at all speeds including zero. The new torque control method is called Feed Forward Torque Control.