Analysis, design and implementation of sensorless V/f control in a surface-mounted PMSM without damper winding

Abstract

This paper presents a novel, reliable and efficient V/f control implementation on a 8-pole, 750 rpm, 5 kW surface-mounted permanent magnet synchronous motor (PMSM) without damper winding. In the absence of a damper winding, open loop V/f control of SM is inherently unstable, particularly at high speeds. Stabilisation can be done with proper stator frequency modulation in accordance with the change in rotor speed to provide for effect of damping. This has been implemented here without use of any shaft-mounted encoder. The change in rotor speed is observed from power perturbation, thereby eliminating the need for using a speed sensor in the drive. The efficiency of the drive is further increased with appropriate control of the power factor, irrespective of load and frequency variations. Simulated and experimental results are presented for both openloop and the proposed V/f control. These results establish the accuracy of the design of the proposed V/f control strategy and the precision of hardware implementation. A comparative study between the proposed V/f control method and standard vector control method, as implemented on this PMSM, has also been presented here to establish the advantages of the proposed scheme. The PMSM itself was designed and fabricated in the laboratory.

Modeling and Dynamics of HTS Motors for Aircraft Electric Propulsion

“…However, open loop variable frequency drive-based voltage source control may not be stable for all frequencies and it may be necessary to include a stabilizing inner loop. The stability and inner loop feedback stabilization of a PMSM with an outer open loop variable frequency drive and a constant load have been considered by many authors [25][26][27][28][29] and will not be reconsidered here. Yet, the methodology is particularly suitable for HTS PMSMs, as the stator resistance of these machines is particularly low.…”

“…Currently, a generic voltage source controller based on a multi-loop control structure and an inner stabilization loop are being developed to control a typical HTS PMSM with a dynamic propeller load that is not constant, and the results of that study will be reported independently. The dynamic model is altered to include the load angle dynamics and the inner loop control law is synthesized by the method reported in [29]. Scaling laws for matching the results of this study to other HTS PMSMs are used to facilitate the design of a distributed propulsion system for an all-electric aircraft.…”

Position Estimation and Compensation Based on a Two-Step Extended Sliding-Mode Observer for a MSFESS

“…In addition, it is a common phenomenon that the rotor displacement can vary in real time, which requires a more difficult installation accuracy for the position sensor and a higher cost and reducer reliability. Therefore, the sensorless control strategy has become a leading issue in the PMSM control field [ 6 , 7 , 8 , 9 ].…”