Design and Modelling of Axially-Laminated Interior Permanent Magnet Motor Drives for Field-Weakening Applications

This thesis is concerned with the design of AC motors to operate at constant shaft power over the widest possible speed range from an inverter of fixed volt-ampere rating. In particular, it examines and validates the reputation of the interior permanent magnet motor drive of having a wide speed range at constant power (field-weakening range). The design and construction of a 7.5kW axially-laminated interior permanent magnet motor showing a constant-power speed range exceeding 7.5:1 is described. This result cannot be matched by any other motor type. Vector-controlled induction motor drives are widely used for field-weakening applications. They offer a constant-power speed range of up to about 4:1. Higher values can be obtained only by oversizing the drive or by using a winding changeover technique. Combined with improvements in low-speed dynamic performance, the inherently wider constant-power speed range makes the interior permanent magnet motor drive a serious contender for applications such as machine tool main spindle drives and traction. The thesis consists of two parts. The first part examines the theoretical and practical limitations to the field-weakening performance of the three types of brushless synchronous AC motor : the surface permanent magnet, the synchronous reluctance and the interior permanent magnet motor. It is shown that high-saliency interior permanent magnet motor drives should offer the best practical field-weakening performance. The axially-laminated (as opposed to the conventional radially-laminated) construction offer the highest saliency ratios. The second part describes the modelling and design of an axially-laminated interior permanent magnet motor drive for optimal field-weakening performance. The effect of varying the design parameters on the drive's field-weakening performance is analysed. A 7.5kW axially-laminated synchronous reluctance and a 7.5kW axially-laminated interior permanent magnet motor were built. The interior permanent magnet motor drive shows an extremely wide constant-power speed range which exceeds 7.5:1

Impact of the motor magnetic model on direct flux vector control of interior PM motors

The stator-field-oriented, direct-flux vector control has been proven to be effective in terms of linear torque control and model independent performance at limited voltage and current (i.e. in flux weakening) for AC drives of various types. The performance of the direct-flux vector control relies on the accuracy of the flux estimation, as for any field oriented control. The knowledge of the motor magnetic model is critical for flux estimation when the operating at low speed. This paper addresses the effects of a limited knowledge of the motor model on the performance of the control at low speed, for an Interior Permanent Magnet motor drive. Experimental results are give

Characterization of Stator Winding Short-Circuit Faults in Interior Permanent-Magnet Motor-Drive Systems

This thesis contains a comprehensive analysis of experimental data collected from a case-study interior permanent-magnet electric machine experiencing winding short-circuit faults of varying severity. The experimental data collected from the faulted machine is from both motoring operation energized by a PWM sensorless ac drive as well as generating operation driven by the test bed dynamometer with a resistive winding load. For both modes of operation a complete set of three-phase voltage and current signals was recorded and analyzed. The three fault diagnosis techniques applied and compared regarding their ability to diagnose and prognosticate a winding fault in an interior permanent-magnet machine are motor current spectrum analysis (MCSA), negative sequence components analysis utilizing a symmetrical components transformation, and the space-vector pendulous oscillation method. The applicability of these diagnosis techniques to this case-study experimental interior permanent- magnet machine demonstrate that motor current spectrum analysis is inconclusive in diagnosing a winding fault when the machine is operated as a motor, but useful for diagnosing a winding fault when the machine is operated as a generator. Negative sequence components analysis successfully diagnoses the winding fault in both the motor operation and the generator operation cases. Finally, the space-vector pendulous oscillation method results are inconclusive for both the motor operation and the generator operation test cases

Self-starting interior permanent magnet motor drive for electric submersible pumps

The interior permanent magnet (IPM) motor drive has evolved as the most energy efficient technology for modern motion control applications. Electric submersible pumps (ESPs) are electric motor driven fluid recovery systems. ESPs are widely used for producing oil and gas from deep downhole reservoirs. Standard ESPs are driven by classical squirrel cage induction motors (IMs) due to its self-starting capability from a balanced 3-phase ac excitation, ruggedness, simplicity, low cost and wide scale availability. Although there has been a tremendous growth in the design and development of highly efficient and reliable IPM motors for traction drive systems, application of the IPM motor technology in ESPs is still in its infancy due to challenges associated with the design and control of IPM motors. In this thesis, a new self-starting, efficient and reliable IPM motor drive technology is proposed for ESP systems to extend their efficiency, longevity and performance. This thesis investigates two different types of self-starting interior permanent magnet (IPM) motors: cage-equipped IPM motors known as line-start IPM motors and a new type of hybrid self-starting motors called hysteresis IPM motors. The limited synchronization capability of line-start IPM motors for high inertial loads is explained in this thesis. To overcome the starting and synchronization problems associated with line-start IPM motors, a new type of hybrid hysteresis IPM motor is proposed in this thesis. Equivalent circuit modeling and finite element analysis of hysteresis IPM motors are carried out in this thesis. A prototype 2.5 kW hysteresis IPM motor is constructed and experimentally tested in the laboratory. In order to limit the inrush current during starting, a stable soft starter has been designed, simulated and implemented for variable speed operations of the motor. The simulation and experimental results are presented and analyzed in this thesis. Self-starting IPM motors suffer from hunting induced torsional oscillations. Electric submersible pumps are vulnerable against sustained hunting and can experience premature failures. In this thesis, a novel stator current signature based diagnostic system for detection of torsional oscillations in IPM motor drives is proposed. The diagnostic system is non-intrusive, fast and suitable for remote condition monitoring of an ESP drive system. Finally, a position sensorless control technique is developed for an IPM motor drive operated from an offshore power supply. The proposed technique can reliably start and stabilize an IPM motor using a back-emf estimation based sensorless controller. The efficacy of the developed sensorless control technique is investigated for a prototype 3-phase, 6-pole, 480V, 10-HP submersible IPM motor drive. In summary, this thesis carried out modeling, analysis and control of different types of self-starting IPM motors to assess their viability for ESP drive systems. Different designs of self-starting IPM motors are presented in this thesis. In future, a fully scalable self-starting IPM motor drive will be designed and manufactured that can meet the industrial demands for high power, highly reliable and super-efficient ESP systems

Resilient Observer Design for Discrete-Time Nonlinear Systems with General Criteria

A class of discrete-time nonlinear system and measurement equations having incrementally conic nonlinearities and finite energy disturbances is considered. A linear matrix inequality based resilient observer design approach is presented to guarantee the satisfaction of a variety of performance criteria ranging from simple estimation error boundedness to dissipativity in the presence of bounded perturbations on the gain. Some simulation examples are included to illustrate the proposed design methodology

Comparison of fault-tolerant operations for permanent-magnet hybrid brushless motor drive

Paper No. CS-06The permanent-magnet hybrid brushless (PMHB) motor adopts both DC field windings and PMs for excitation. It not only offers effective online flux control, but also flexible brushless DC (BLDC) or brushless AC (BLAC) operations. The key of this paper is to investigate two remedial strategies for fault-tolerant operations of the PMHB motor drive under open-circuit faults. First, by utilizing field excitation boosting, the reduced torque due to one phase loss can be remedied, the so-called remedial BLDC operation mode. Second, by reconstructing armature fields due to the healthy phase currents, the reduced torque can also be remedied, the so-called remedial BLAC operation mode. Finally, these two remedial operation modes are compared and verified by experimentation, hence confirming the validity of the proposed fault-tolerant PMHB motor drive. © 2006 IEEE.published_or_final_versionThe 11th Joint Magnetism and Magnetic Materials - INTERMAG Conference, Washington, DC., 17-21 January 2010. In IEEE Transactions on Magnetics, 2010, v. 46 n. 6, p. 1378-138

Investigation of the transient and steady state operations of two Line Start Permanent Magnet Motors (LSPMMS) with different rotor configurations

This paper investigates the transient and steady state operations of two Line Start Permanent Magnet Motors (LSPMMs) with different rotor types. The calculations showed that both designs can reach a higher efficiency than comparable induction motorsof the same size. The loading capability of the Surface Permanent Magnet (SPM) rotor is better than the Interior Permanent Magnet (IPM) rotor on asynchronous rotation as it has lesser torque ripples. However, IPM rotor had less flux leakage and copper losses at the synchronous operation under the same loading conditions.The results of the investigation also show that IPM motor attains a higher speed responses than SPM motor but SPM motor synchronizes faster than the IPM motor under the same loading conditions. During the asynchronous period, the chracteristics of both machines display similar features at a lower load torque less than 50N-m. The ripple contents of IPM is greater than that of SPM as can be observed in the run-up speed characteristics where IPM shows spontaneous overshoot. The pull out torque for SPM and IPM occurred at the time of 6 and 10 second respectively with same load increments.Keywords: synchronous, asynchronous, motor, permanent magnet, torqu

Extended state observer-based vector control for PMSM drive system with single phase current sensor

© 2017 IEEE. A novel extended state observer (ESO)-based vector control (VC) strategy is developed for permanent magnet synchronous motor (PMSM) drive systems with only one phase current sensor. Generally, to achieve high precision control, two phase current sensors are indispensable for successful operation of the feedback control. In response to a phase current sensor fault, by use of technique of ESO, a new observer for estimating both the remaining two phase currents and time-varying stator resistance is put forward. To improve the performance and decrease system high frequency vibration, a nonlinear exponential function is used to replace the switch function in conventional ESO. The resultant ESO-based VC strategy for PMSM drive system with single phase current sensor has strong robustness and satisfactory control performance. Numerical simulation validates the feasibility and effectiveness of the proposed scheme

Neural-Network Vector Controller for Permanent-Magnet Synchronous Motor Drives: Simulated and Hardware-Validated Results

This paper focuses on current control in a permanentmagnet synchronous motor (PMSM). The paper has two main objectives: The first objective is to develop a neural-network (NN) vector controller to overcome the decoupling inaccuracy problem associated with conventional PI-based vector-control methods. The NN is developed using the full dynamic equation of a PMSM, and trained to implement optimal control based on approximate dynamic programming. The second objective is to evaluate the robust and adaptive performance of the NN controller against that of the conventional standard vector controller under motor parameter variation and dynamic control conditions by (a) simulating the behavior of a PMSM typically used in realistic electric vehicle applications and (b) building an experimental system for hardware validation as well as combined hardware and simulation evaluation. The results demonstrate that the NN controller outperforms conventional vector controllers in both simulation and hardware implementation

Design, analysis, and control of DC-excited memory motors

In this paper, a new type of memory motors, namely the dc-excited memory motor, is proposed and implemented. The concept of dc-excited memory is due to the nature that the magnetization level of permanent magnets (PMs) in the motor can be regulated by a temporary dc current pulse and be automatically memorized. Based on an outer-rotor doubly salient motor structure, the proposed dc-excited memory motor can offer effective and efficient online air-gap flux control. Hence, it possesses the advantages of mechanical robustness, high efficiency, and wide constant power operation region. Both simulation and experimentation are carried out to verify the validity of the proposed motor. © 2010 IEEE.published_or_final_versio