Current Controller for Low-Frequency Signal Injection and Rotor Flux Position Tracking at Low Speeds

Rotor flux spatial position can be tracked in an ac machine even at low or zero stator frequency if a low-frequency harmonic current signal is injected into its stator. The harmonic current injection is source of the rotor speed perturbations which induce voltage oscillations in the stator winding at the injected frequency. By analyzing the stator winding voltage response, it is possible to detect the rotor flux position regardless of the stator frequency. This paper presents a stator current controller that is suitable for imposing rotating or pulsating harmonic current injection and a method for tracking the rotor flux position in either induction machines (IMs) or permanent-magnet synchronous machines (PMSMs). The controller contains, in addition to the standard fundamental-frequency-based synchronous reference frame (SRF) current controller, two sets of harmonic current integral controllers placed in respective harmonic SRFs. Such an extended current controller simultaneously performs two important tasks: controlled harmonic current injection with zero steady-state error and separation of particular spectral components in the stator voltage (spectral/sequence decomposition) which contain the rotor flux position information. The theoretical analysis presented, based on perturbation theory and averaging techniques, gives general expressions which link the rotor flux position error in IM and PMSM to the harmonic current controller outputs. Two special cases with the rotational and pulsating harmonic current injections are considered in more detail. The validity of the theoretical analysis and the feasibility of the sensorless rotor flux position detection are experimentally verified.

[1]  P. Vas.  Vector control of AC machines , 1990 .

[2]  Mark Sumner,et al.  Hybrid rotor position observer for wide speed-range sensorless PM motor drives including zero speed , 2006, IEEE Transactions on Industrial Electronics.

[3]  J. Luomi,et al.  Rotor flux angle tracking controller for sensorless induction motor drives , 2002, Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344).

[4]  J. Luomi,et al.  Flux observer enhanced with low-frequency signal injection allowing sensorless zero-frequency operation of induction motors , 2003, 38th IAS Annual Meeting on Conference Record of the Industry Applications Conference, 2003..

[5]  S. Sul,et al.  Sensorless drive of surface-mounted permanent-magnet motor by high-frequency signal injection based on magnetic saliency , 2003 .

[6]  Ralph Kennel,et al.  Sensorless speed and position control of synchronous machines using alternating carrier injection , 2003, IEEE International Electric Machines and Drives Conference, 2003. IEMDC'03..

[7]  P. Olver.  Nonlinear Systems , 2013 .

[8]  Robert D. Lorenz,et al.  Transducerless field orientation concepts employing saturation-induced saliencies in induction machines , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[9]  Thomas G. Habetler,et al.  Using PWM-Induced Transient Excitation and Advanced Signal Processing for Zero-Speed Sensorless Control of AC Machines , 2010, IEEE Transactions on Industrial Electronics.

[10]  G.K. Venayagamoorthy,et al.  Multiple Reference Frame-Based Control of Three-Phase PWM Boost Rectifiers under Unbalanced and Distorted Input Conditions , 2008, IEEE Transactions on Power Electronics.

[11]  Ralph Kennel,et al.  Sensorless position control of permanent magnet synchronous machines without limitation at zero speed , 2002, IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02.

[12]  H. Tuusa,et al.  Sensorless control of salient pole PMSM using a low-frequency signal injection , 2005, 2005 European Conference on Power Electronics and Applications.

[13]  Veli-Matti Leppänen,et al.  Speed-sensorless induction Machine control for zero speed and frequency , 2004, IEEE Transactions on Industrial Electronics.

[14]  Yongdong Li,et al.  Comparison of signal injection methods for sensorless control of PMSM at very low speeds , 2007, 2007 European Conference on Power Electronics and Applications.

[15]  Seung-Ki Sul,et al.  New stand-still position detection strategy for PMSM drive without rotational transducers , 1994, Proceedings of 1994 IEEE Applied Power Electronics Conference and Exposition - ASPEC'94.

[16]  Seung-Ki Sul,et al.  A harmonic reference frame based current controller for active filter , 2000, APEC 2000. Fifteenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.00CH37058).

[17]  T. A. Lipo,et al.  New observer-based DFO scheme for speed sensorless field-oriented drives for low-zero-speed operation , 1998 .

[18]  J. Luomi,et al.  Sensorless control of surface magnet synchronous motors at low speeds using low-frequency signal injection , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[19]  Hirofumi Akagi,et al.  An approach to real-time position estimation at zero and low speed for a PM motor based on saliency , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[20]  Veli-Matti Leppänen,et al.  Observer using low-frequency injection for sensorless induction motor Control-parameter sensitivity analysis , 2006, IEEE Transactions on Industrial Electronics.

[21]  Duro Basic,et al.  Harmonic filtering of high-power 12-pulse rectifier loads with a selective hybrid filter system , 2001, IEEE Trans. Ind. Electron..