Online CrossCoupling and Self Incremental Inductances Determination of

Online Cross-Coupling and Self Incremental Inductances Determination of Salient Permanent Magnet Synchronous Machines Dr. Georges El-Murr Power Electronics, Drives and Machines Research Group Dr. Damian Giaouris Professor John W. Finch

Contents Sensorless control Signal Injection Schemes PLL conventional observer Proposed demodulation process Cross saturation effects Incremental self and cross-coupling inductances estimation Estimation results

Sensorless Control Implementation of high performance control method such as Vector control requires SPEED AND POSITION SENSOR This SENSOR (encoder, transducer…) is EXPENSIVE, FRAGILE and need REGULAR MAINTENANCE Objective is to control accurately AC machines WITHOUT speed and position feedback sensor

Sensorless Control Parameter dependent Parameter independent Superiority at zero fundamental frequency

Signal Injection Schemes Presence of rotor position related SALIENCY/ANISOTROPY is essential üAsymmetric Rotor Structure üSymmetric Rotor Structure

Signal Injection Schemes Presence of rotor position related SALIENCY/ANISOTROPY is essential Injected high frequency voltage is SUPERIMPOSED to the fundamental voltage

Signal Injection Schemes Presence of rotor position related SALIENCY/ANISOTROPY is essential Injected high frequency voltage is SUPERIMPOSED to the fundamental voltage Resultant carrier signal is modulated by the rotor position information

PLL Conventional Observer Phase Locked-Loop (PLL) is a closed loop control strategy used to track the rotor speed and position 1. PROBLEMS!! Parasitic effects of POWER ELECTRONIC DEVICES (nonlinearity of the PWM inverter) affect the accuracy of the estimated speed and position

Proposed demodulation process

More Problems 2. Cross-saturation effects DEVIATES the estimated saliency position from actual rotor position üNo-Load üHeavy-Load Carrier current signal

Cross Saturation Effects Phase error information are attached to the negative sequence of the carrier current Phase error is proportional to the cross-coupling inductance

Conventional Compensation TO COMPENSATE FOR THIS ERROR Determine Incremental Crosscoupling or mutual inductance Ldq Pre-determine Incremental self inductances Lq , Ld Look-up Table Position error ε according to applied load

Proposed Incremental Inductances Estimation Incremental inductances can be found in 2 steps: 1. Goertzel Algorithm Positive sequence current amplitude K 1 2. Proposed demodulation technique Negative sequence current amplitude K 2

Proposed Online Compensation At no-load INDEPENDENT FROM POSITION INFORMATION At load !!!!

Estimation Results Ld= 0. 5 H Lq=0. 18 H Ldq=0. 1 H

Conclusion Presence of rotor saliency/anisotropy is essential for signal injection schemes Under certain operating conditions determination of high frequency inductances cannot be avoided Proposed scheme: ü Simple and easy to implement ü Provide accurate inductances estimation ü Doesn’t require large memory usage ü Can be used for online incremental inductances estimation Suitable for SENSORLESS CONTROL since inductances calculation can be INDEPENDENT from rotor position

Thank you. . .

Millennium Bridge – Newcastle upon Tyne