Hybrid Position Sensorless Control of a RSM in the rated speed range Francois Barnard Stellenbosch University Energy Postgraduate Conference 2013

The RSM Reluctance Synchronous Machine No conductive material (copper/aluminium) on rotor Comparable performance under closed-loop control with feedback RSM ASDs have higher operating efficiency compared to induction machine ASDs

Position Sensor RSM drives require speed/position information Position sensors unreliable in comparison with complete system Increase overall cost of systems Position estimation eliminates the need for a position sensor

Position Estimation Fundamental model techniques (medium to high speed) Signal injection saliency based techniques (standstill to low/medium speed) Viable with modern technology No single estimation technique sufficiently capable for all operating conditions Hybrid techniques implement different schemes at different speeds

Active Flux Method

Active Flux Method

Active Flux Method Simulated speed step response

Active Flux Method Simulated rotor angle tracking (4% error)

Arbitrary Injection Used with standard field oriented control (FOC), including Space Vector Modulation No particular injection voltage required, only the presence of a current derivative Smaller percentage bus voltage than common High Frequency Injection method – higher torque Adapted to be parameter insensitive – detect motor parameters in the algorithm

Arbitrary Injection Discrete model derived using Euler approximation of integration FOC scheme disregards rotor saliency in estimation (using isotropic machine model) Actual rotor saliency causes estimation error Estimation error and applied voltage information allows calculation of rotor position

Hybrid Controller Arbitrary injection estimated angle used to reconstruct active flux vector at low speeds Deliver sensorless control in entire rated speed range Control applicable to variable speed generator Use as part of a wind turbine system Image courtesy of Anusorn P nachol / FreeDigitalPhotos.net