Spectral overlap of saliency signal components in injection based sensorless controlled induction machines

Sensorless control techniques of ac machines based on fundamental wave methods have a critical point of operation at zero frequency. Using signal injection methods zero frequency operation is possible, however another critical point of operation may exist at overlap frequencies which, so far has not been addressed by research. The resulting signals from injection based sensorless control methods are composed of components caused by saturation, slotting or anisotropy saliencies, as well as inter-modulation effects. The point of operation where the frequency of the slotting saliency equals the frequency of the saturation saliency is critical in terms of control performance as then a reliable separation is only possible feed forward. A mathematical description of the relation between the mechanical speed and load torque at the overlap of the slotting and saturation frequencies is given. Measurement results at specific points of operation are shown to point out that the critical point of operation is no longer zero speed or zero frequency but may be one of the operating states where an overlap in frequencies exists.

[1]  Joachim Holtz.  Sensorless Position Control of Induction Motors , 1998 .

[2]  Qiang Gao,et al.  Position Estimation of AC Machines Over a Wide Frequency Range Based on Space Vector PWM Excitation , 2007, IEEE Transactions on Industry Applications.

[3]  P. Garcia,et al.  Saliency tracking-based, sensorless control of AC machines using structured neural networks , 2005, Fourtieth IAS Annual Meeting. Conference Record of the 2005 Industry Applications Conference, 2005..

[4]  Th. M. Wolbank,et al.  A modified PWM scheme in order to obtain spatial information of AC machines without mechanical sensor , 2002, APEC. Seventeenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.02CH37335).

[5]  Qiang Gao,et al.  Sensorless Position and Speed Control of Induction Motors Using High-Frequency Injection and Without Offline Precommissioning , 2007, IEEE Transactions on Industrial Electronics.

[6]  Jung-Ik Ha,et al.  Sensorless field orientation control of an induction machine by high frequency signal injection , 1997, IAS '97. Conference Record of the 1997 IEEE Industry Applications Conference Thirty-Second IAS Annual Meeting.

[7]  Kaushik Rajashekara,et al.  Sensorless control of AC motor drives : speed and position sensorless operation , 1996 .

[8]  M. Schroedl,et al.  Sensorless control of AC machines at low speed and standstill based on the "INFORM" method , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[9]  T.G. Habetler,et al.  Integration of transient and fundamental wave excitation for zero speed sensorless control of AC machines , 2008, 2008 18th International Conference on Electrical Machines.

[10]  Joachim Holtz.  Sensorless position control of induction motors-an emerging technology , 1998, IECON '98. Proceedings of the 24th Annual Conference of the IEEE Industrial Electronics Society (Cat. No.98CH36200).

[11]  Alfio Consoli,et al.  A new zero frequency flux position detection approach for direct field oriented control drives , 1999, Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370).