PM-RSM sensorless vector control: Zero q-axis flux versus approximate maximum torque per current, with experiments

This paper presents two control strategies for the sensorless vector control of permanent magnet reluctance synchronous motor (PM-RSM) in a wide speed range: the zero q-axis flux control and an approximate maximum torque per current control. The approximate maximum torque per current control is a novel torque - dq current referencer which is capable to develop maximum available motor toque for an optimal dq current pair below base speed (maximum torque/ampere), but also in flux weakening region (above base speed) where voltage limitations impose constraints on the allowable dq currents. The motion sensorless control of the PM-RSM is obtained via model-based stator flux estimation using the “active flux” concept. Experimental results between 30 rpm and 3000 rpm, at low (25%) rated voltage, validate the two control systems up to a speed equal eight times the machine base speed. Finally, a comparison between the experimental results employing both control systems has been done.