Hybrid Position Sensorless Control of aRSM in the ratedspeed rangeFrancois BarnardStellenbosch 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