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Axial–radial flux type permanent magnet synchronous machine can adjust air gap flux, which provides a new strategy for flux regulation of a permanent magnet motor. In this article, the structure of the ferromagnetic bridge is optimized by analyzing the magnetic circuit structure of Numerical anlysis of an axial-radial flux type fully superconducting synchronous motor (ARFTFSSM). The three-dimensional finite-element model of the motor is established by using the finite-element method, and the changes of air gap flux density and back electromotive force are compared through the finite-element prediction. The results show that the optimized ferromagnetic bridge has better magnetic regulation performance. On this basis, the eddy current distribution and eddy current loss of two kinds of ferromagnetic bridge structures are further compared and analyzed. Finally, the experimental results verify the accuracy of the calculation, and the research results can provide a reference for the further study of hybrid excitation motor. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a novel low-cost speed sensorless control technique for a permanent magnet assisted synchronous reluctance motor (PMa-SynRM). A robust adaptive speed (RAS) observer is designed for estimating the rotor speed and position, respectively. The RAS observer estimates the PMa-SynRM speed and position from the back electromotive force space-vector determination without voltage sensors by using the reference voltages issued from the current controllers instead of the actual ones. The novelty of the proposed RAS estimation technique is the adaptation of the feedback error of the actual values. Thus, the proposed observer structure promises a higher degree of robustness against PMa-SynRM parameter changes in the sensitivity analysis presented in this paper. The dynamic model and experimental realizations of the proposed control technique are introduced. A 6-kW PMa-SynRM drive test setup is constructed including a dSPACE 1104 board as the control heart of the proposed system. The hardware-in-the-loop Typhoon HIL 402 device is used to experimentally emulate the PMa-SynRM and the inverter connected to a dSPACE MicroLabBox. The proposed RAS observer robustness is evaluated using a HIL model and experimental results under different conditions. A comparative experimental analysis between the proposed RAS and Luenberger observers has been performed. [ABSTRACT FROM AUTHOR]

A novel approach of exploiting the stator-temperature-monitoring system to perform sensorless rotor-position estimation is described in this paper. The rotor position is, in fact, estimated by processing the voltages induced in thermistor cablings, which are modified in order to work as search coils (SCs). Using SCs, some typical drawbacks of sensorless position-estimation techniques based on the manipulation of fundamental components of stator voltages and currents, such as those related to inverter non-linearities, stator-resistance voltage drops, magnetic saturation and cross-coupling, can be overcome or mitigated. According to the proposed approach, a rotor-position-tracking technique for synchronous reluctance motor drives is developed independently from motor parameters. Such a sensorless rotor-position-estimation technique can be directly used to build up a sensorless controller or to improve the performance of conventional model based sensorless control systems. Simulations and experimental tests confirm the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper extends the application of a frame-angle-based (FAB) direct torque controller (DTC) for permanent magnet synchronous motor (PMSM) drives to low and very low speeds. The FAB-DTC is intended for PMSM drives that are fed by $3\phi$ six-pulse wavelet-modulated dc–ac converters. The foundations of the FAB-DTC are based on regulating the $d\text{--}q$ -axis stator voltages, in response to variations in the load torque and/or drive speed. The adjustments in $d\text{--}q$ -axis stator voltages are created by changing the angle $\vartheta$ of the frame spanned by the $d\text{--}q$ -axis stator voltages. In order to extend the FAB-DTC to low and very low speeds, the changes in $\vartheta$ are accompanied by changes in the maximum scale. The values of maximum scale and $d\text{--}q$ -axis stator voltages are used to update or change the reference signals employed by the wavelet modulation to generate switching pulses to operate a $3\phi$ dc–ac converter. The complete PMSM drive system incorporating the modified FAB-DTC is implemented for a 10-hp PMSM drive system. The performance of the FAB-DTC is investigated for different changes in the command torque for various low and very low speeds. Performance results demonstrate stable, fast, dynamic, and accurate responses, which have minor sensitivity to variations in load torque and/or drive speed. [ABSTRACT FROM AUTHOR]

This paper deals with the speed and position estimation for synchronous reluctance motors (SyRMs) and interior permanent-magnet synchronous motors (IPMs). A unified design and analysis framework for a class of back electromotive force-based observers is developed and the links between apparently different estimation methods are brought out. State observers equipped with a speed-adaptation law are shown to be mathematically equivalent to voltage-model-based flux observers equipped with a position-tracking loop. The error signal driving the adaptation law or the tracking loop is presented in a generalized form. Using the framework, a stabilizing gain design is reviewed and detailed design guidelines are given. Selected observer designs are experimentally evaluated using a 6.7-kW SyRM drive and a 2.2-kW IPM drive. [ABSTRACT FROM AUTHOR]

The paper aims to provide a guideline for rotor design of permanent magnet (PM) assisted synchronous reluctance machine (PMa-SynRM). Unlike interior PM machines, the PMa-SynRM is essentially an SynRM with dominant reluctance torque. The PMa-SynRM is often designed by directly embedding magnets into an SynRM rotor to improve the performance. However, how the PMs can be arranged in the rotor to enhance motor performance has not been fully discussed. This paper investigates the influence of several key factors concerning the PM arrangements, including number of PM layers, inserted positions, and PM sizes. The torque, flux linkages, power factor, and motor performance are comprehensively evaluated. Based on the analysis, a brief guideline is suggested for PMa-SynRM rotor design. Finite element analysis is used for evaluation and experiments are conducted to validate the analysis. [ABSTRACT FROM AUTHOR]

Sensorless control of synchronous reluctance motors (SyRMs) relies on the knowledge of the machine current-to-flux maps. Previous work demonstrated the feasibility of sensorless identification of the flux maps, performed by exciting the machine with square-wave voltage pulses at standstill, and without the need of rotor locking. The rotor position was initially estimated and then used throughout the identification, in open-loop fashion. In some cases, rotor oscillation and eventually position drift led to stop the identification before the programmed $dq$ current domain was covered entirely. In this paper, the rotor position is closed-loop tracked during the motor commissioning to counteract the occurrence of rotor movement. The hysteresis-controlled excitation voltage is augmented with an high-frequency (HF) square-wave voltage component, and the position is tracked through demodulation of the current response to such HF component. The proposed approach is experimentally verified on a 2.2-kW SyRM prototype. The results show that the $i_d, i_q$ commissioning domain is substantially extended, resulting in more accurate flux maps. Moreover, self-tuning of the method is addressed and possible causes of error are analyzed and commented. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous machines (PMSMs) are popular due to their high efficiency and favorable dynamic properties. In practice, these machines often have a back-electromotive force (EMF) waveform, which deviates from a theoretically ideal sinusoid or trapezoid. In the past, current waveform shaping techniques were developed for these machines to calculate nonconventional current waveforms to reduce the torque ripple. However, in the light of global warming, energy efficiency has become more important than torque ripple in many applications. Therefore, current waveform shaping techniques can be used to focus on maximum efficiency. In this paper, a technique is presented that maximizes the efficiency of both the PMSM and the drive simultaneously. A time domain approach is used instead of the classical frequency domain approach, which allows us to include many machine aspects that had to be neglected previously, i.e., armature reaction, reluctance, zero-sequence components, and iron losses. [ABSTRACT FROM AUTHOR]

In this paper, a vernier motor with a spoke permanent-magnet (PM) structure instead of a surface PM is proposed in order to obtain higher power factor (PF) and flux density. However, upon investigating this structure with a single gap, unique effects that virtually eliminate the vernier effect are analytically identified. To avoid these effects and improve the PF, a spoke PM vernier motor with a double gap is then proposed. Analytic equations for back electromotive force and the PF are then derived for this motor in terms of various geometric factors such as the numbers of magnets and winding poles, the magnet thickness, etc. For a case study, the practical achievable maximum power and PF are calculated and verified with accurate simulations. [ABSTRACT FROM AUTHOR]

This paper presents an extended electromotive-force-based discrete-time sliding-mode observer (DSMO) for rotor position/speed sensorless control of interior permanent-magnet synchronous machines (IPMSMs). Without using voltage sensors to measure IPMSM terminal voltages, the reference voltages generated by the vector control system are used as inputs for the DSMO. However, due to the inverter dead-time effect, the mismatch between the reference voltages and actual terminal voltages will degrade the performance of DSMO. In this paper, the periodically oscillating rotor position estimation error caused by the dead-time is first analyzed. Then, a dead-time compensation scheme is proposed to mitigate this position estimation error. The proposed DSMO with the dead-time compensation scheme is validated on an IPMSM control system used in heavy-duty, off-road, hybrid, and electric vehicles. [ABSTRACT FROM AUTHOR]

The so-called integrated starter–alternator (ISA) is a high-efficiency electrical machine that is connected to an internal combustion engine obtaining mild hybrid electric vehicles. The ISA has a twofold task: starting up the engine and generating electrical energy to be stored into a battery. This paper is focused on the first task. Two different motors are investigated: an external rotor surface permanent magnet (SPM) machine and an interior permanent magnet (IPM) machine. For drive control, both motors require knowledge of their rotor position; then, a sensorless technique based on the high-frequency (HF) voltage injection for rotor position detection has been implemented. In order to create an HF anisotropy in the SPM rotor configuration, a ringed-pole solution has been adopted. Experimental tests have highlighted that the first machine has a clear capability of starting up the engine with good speed and position estimation in spite of the particular nonconstant load torque. As regard the IPM machine, the sensorless engine startup appears not possible because the anisotropy disappears at a high current level due to saturation effects. [ABSTRACT FROM PUBLISHER]

This paper presents an in-depth comparative analysis of the variable speed drive (VSD) performance between an IEC frame size 90 four-pole three-phase induction motor (IM) and the equal line-start interior permanent magnet synchronous motor (LSIPMSM). Employing measurement data from no-load tests, load tests, and temperature-rise tests of the aforementioned motors and different cage materials as well, the motors' no-load and load characteristics are first examined in detail and then the drives' characteristics are analyzed in open-loop volts per hertz ( V\!/\!f) control by using the same voltage-source inverter and the aforementioned IM or LSIPMSM in both constant torque and constant power operation. It has been established that particularly the motors' current and power factor characteristics have distinct impact on the consequent VSD performance in terms of loss and efficiency. Furthermore, it has been shown that the lower loss of the LSIPMSM enables a significant increase of the VSD's constant power range. [ABSTRACT FROM AUTHOR]

The magnetic coupling problem is discussed for the six topologies of compound-structure permanent-magnet (PM) synchronous machine (CS-PMSM), and the radial–radial flux CS-PMSM is investigated as example. Taking Toyota Prius hybrid system as reference, a radial–radial flux CS-PMSM is designed. Owing to mechanical reason, the thicknesses of the PMs on the outer and inner sides of the outer rotor are quite different, which induces more coupling problem. The magnetic system of CS-PMSM is researched in two aspects: the combination of thicknesses of PM and outer rotor yoke and the effect due to armature reaction. It is concluded that the magnetic coupling problem can be solved by designing an appropriate outer rotor thickness. In order to evaluate the magnetic structure, a downsized radial–radial flux CS-PMSM prototype was designed and manufactured. Back electromotive force (BEMF), relations between torque and current, and efficiency of the prototype were measured, and the experimental results are in good accordance with the calculated results. [ABSTRACT FROM AUTHOR]

This paper provides and analyzes a simple, robust, and universal model for rotor position estimation for synchronous machines. The rotor position is estimated using an equivalent electromotive force (EMF) model of a synchronous machine or, alternately, using a sliding-mode observer (SMO) based on the equivalent EMF model. The SMO provides fast convergence and low sensitivity to parameter variations. Experimental results with a 3.7-kW interior-permanent-magnet machine have validated the effectiveness of the proposed equivalent EMF scheme. [ABSTRACT FROM AUTHOR]

Although it is widely known that back-electromotive-force tracking has a low-speed limit, there is very little published literature evaluating this limit. This paper shows that the low-speed limit is mainly a function of the amplitude of the inverter harmonics and that theory and simulation will provide erroneous results when inverter harmonics are not incorporated. This paper will also provide a method for evaluating this low-speed limit using drive stiffness as the metric. The experimental results show quantitatively how the drive stiffness suffers as speed decreases, which ultimately sets the practical low-speed limit. [ABSTRACT FROM PUBLISHER]

In this paper, the rotor position of a synchronous reluctance motor is estimated exploiting the natural saliency of the machine through an addition of a small high-frequency sinusoidal voltage to the stator voltage reference. Due to rotor saliency, a stator voltage component is generated orthogonal to the added signal, whose amplitude depends on the phase displacement between the d-axis and the direction of the injected signal. A robust rotor position tracking can be accomplished by adjusting the direction of the carrier voltage in order to minimize the amplitude of the generated orthogonal voltage. The proposed technique allows zero-speed operation, does not require additional voltage or current sensors, and can easily correct the influence of the armature reaction. Experimental results confirm the validity of the proposed sensorless technique. [ABSTRACT FROM AUTHOR]