Self-Commissioning Algorithm for Inverter Nonlinearity Compensation in Sensorless Induction Motor Drives

In many sensorless field-oriented control schemes for induction motor (IM) drives, flux is estimated by means of measured motor currents and control reference voltages. In most cases, flux estimation is based on the integral of back-electromotive-force (EMF) voltages. Inverter nonlinear errors (dead-time and on-state voltage drops) introduce a distortion in the estimated voltage that reduces the accuracy of the flux estimation, particularly at low speed. In the literature, most of the compensation techniques of such errors require the offline identification of the inverter model and offline postprocessing. This paper presents a simple and accurate method for the identification of inverter parameters at the drive startup. The method is integrated into the control code of the IM drive, and it is based on the information contained in the feedback signal of the flux observer. The procedure applies, more in general, to all those sensorless ac drives where the flux is estimated using the back-EMF integration, not only for IM drives but also for permanent-magnet synchronous motor drives (surface-mounted permanent magnet and interior permanent magnet). A self-commissioning algorithm is presented and tested for the sensorless control of an IM drive, implemented on a fixed-point DSP. The feasibility and effectiveness of the method are demonstrated by experimental results.

[1]  Joachim Holtz,et al.  Sensorless control of induction motor drives , 2002, Proc. IEEE.

[2]  Cristian Lascu,et al.  Sliding-mode observer and improved integrator with DC-offset compensation for flux estimation in sensorless-controlled induction motors , 2006, IEEE Transactions on Industrial Electronics.

[3]  D. Schlegel,et al.  Effects of parasitics on the control of voltage source inverters , 2003 .

[4]  J. Holtz,et al.  Drift and parameter compensated flux estimator for persistent zero stator frequency operation of sensorless controlled induction motors , 2002, Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344).

[5]  Robert D. Lorenz,et al.  A physically insightful approach to the design and accuracy assessment of flux observers for field oriented induction machine drives , 1992, Conference Record of the 1992 IEEE Industry Applications Society Annual Meeting.

[6]  S. Bolognani,et al.  Self-commissioning compensation of inverter non-idealities for sensorless AC drives applications , 2002 .

[7]  H. Kubota,et al.  DSP-based speed adaptive flux observer of induction motor , 1991, Conference Record of the 1991 IEEE Industry Applications Society Annual Meeting.

[8]  Li Yongdong,et al.  Direct torque control of induction motor for low speed drives considering discrete effects of control and dead-time of inverter , 1997, IAS '97. Conference Record of the 1997 IEEE Industry Applications Conference Thirty-Second IAS Annual Meeting.

[9]  Seung-Ki Sul,et al.  Inverter output voltage synthesis using novel dead time compensation , 1996 .

[10]  R. Bojoi,et al.  Performance Comparison of Sensorless Field Oriented Control Techniques for Low Cost Three-Phase Induction Motor Drives , 2007, 2007 IEEE Industry Applications Annual Meeting.

[11]  C. Schauder,et al.  Adaptive speed identification for vector control of induction motors without rotational transducers , 1989, Conference Record of the IEEE Industry Applications Society Annual Meeting,.

[12]  H. Schierling.  Fast and reliable commissioning of AC variable speed drives by self-commissioning , 1988, Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting.

[13]  Timothy J. E. Miller,et al.  Computer-aided design of electrical machines , 2004 .

[14]  R. Bojoi,et al.  Sensorless Direct Field Oriented Control of Three-Phase Induction Motor Drives for Low Cost Applications , 2006, Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting.

[15]  A. Tani,et al.  Performance analysis of a speed sensorless induction motor drive based on a constant switching frequency DTC scheme , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[16]  Frede Blaabjerg,et al.  An Ideal PWM-VSI Inverter with Feedforward and Feedback Compensation , 1993 .

[17]  Russel J. Kerkman,et al.  Pulse-based dead-time compensator for PWM voltage inverters , 1997, IEEE Trans. Ind. Electron..

[18]  Russel J. Kerkman,et al.  Pulse based dead time compensator for PWM voltage inverters , 1995, Proceedings of IECON '95 - 21st Annual Conference on IEEE Industrial Electronics.

[19]  J. Holtz,et al.  Sensorless vector control of induction motors at very low speed using a nonlinear inverter model and parameter identification , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[20]  Thomas G. Habetler,et al.  Zero-speed tacholess IM torque control: simply a matter of stator voltage integration , 1998 .