Design optimization and performance analysis methodology for PMSMs to improve efficiency in hydraulic applications

Pla de Doctorats Industrials de la Generalitat de CatalunyaIn the recent years, water pumping and other hydraulic applications are increasingly demanding motors capable to operate under different working conditions, including variable pressure and volumetric flow demands. Moreover, the technical evolution trend of pumping components is to minimize the size, offering compact and adaptable hydraulic units. Hence, the need to optimize the electric motor part to reduce the volume according this trend, maximizing the efficiency, decreasing material and fabrication costs, reducing noise and improving thermal dissipation have originated the research field of this project. So far different methodologies have been focused on designing electrical machines considering few aspects, such as the rated conditions with some size limitations. In addition, the optimization strategies have been based on single operation conditions, improving multiple aspects but not considering the overall performance of the machine and its influence with the working system. This research changes the design and optimization paradigm, focusing on defining beforehand the desired performance of the electrical machine in relation with the application system. The customization is not limited to an operating point but to the whole performance space, which in this case is the torque-speed area. Thus, the designer has plenty of freedom to study the system, and define the desired motor performance establishing the size, thermal and mechanical limitations from the beginning of the process. Moreover, when designing and optimizing electrical machines, the experimental validation is of major importance. From an industrial scope so far, the testing methodologies are focused on evaluating point by point the electrical machine performance, being a robust and trustable way to measure and validate the electrical machine characteristics. Nevertheless,this method requires a large time to prepare the experimental setup and to evaluate the whole motor performance. For this reason, there is a special interest on improving parameter estimation and performance evaluation techniques for electrical machines to reduce evaluation time, setup complexity and increase the number of physical magnitudes to measure in order to have deeper information. This research also develops methodologies to extend the electrical machine experimental validation providing information to evaluate the motor performance. This doctoral thesis has been developed with a collaboration agreement between UPC and the company MIDTAL TALENTOS S.L. The thesis is included within the Industrial Doctorates program 2018 DI 019 promoted by the Generalitat de Catalunya.En los últimos años, el bombeo de agua, entre otras aplicaciones hidráulicas, exige cada vez más motores capaces de operar en diferentes condiciones de trabajo, incluyendo las demandas variables de presión y caudal volumétrico. Además, la evolución técnica de los componentes de bombeo está cada vez más minimizando el tamaño ofreciendo unidades hidráulicas compactas y adaptables. De ahí la necesidad de optimizar la parte del motor eléctrico para reducir el volumen de acuerdo con esta tendencia, maximizando la eficiencia, disminuyendo los costos de material y fabricación, reduciendo el ruido y mejorando la disipación térmica. Todos estos factores han creado el campo de investigación sobre el cual se desarrolla este proyecto. Hasta ahora las metodologías se han centrado en diseñar las máquinas eléctricas considerando unos pocos aspectos técnicos, como las condiciones nominales con algunas limitaciones de tamaño. Además, las estrategias de optimización se han basado en condiciones de operación única, mejorando múltiples aspectos sin considerar el rendimiento general de la máquina y su influencia en el sistema de trabajo. Esta investigación cambia el paradigma de diseño y optimización centrándose en definir de antemano el rendimiento deseado de la máquina eléctrica en relación con el sistema de aplicación. La personalización no se limita a un punto de funcionamiento sino a todo el espacio de operación, que en este caso se expresa en el espacio par-velocidad. Así, el diseñador tiene libertad para estudiar el sistema, definir el rendimiento deseado del motor estableciendo el tamaño, limitaciones térmicas y mecánicas desde el inicio del proceso. Además, a la hora de diseñar y optimizar máquinas eléctricas, la validación experimental es de gran importancia. En el ámbito industrial hasta ahora, las metodologías de ensayo han sido enfocadas a evaluar punto por punto la máquina eléctrica, siendo una forma robusta y confiable de medir y validar sus características. Sin embargo, este método requiere mucho tiempo para preparar la configuración experimental y evaluar el motor en toda su zona de operación. Por esta razón, existe un interés especial en mejorar la estimación de parámetros y las técnicas de evaluación de la operación de las máquinas eléctricas reduciendo tiempo, complejidad y aumentando el número de magnitudes físicas a medir teniendo más información sobre la máquina. Esta investigación también desarrolla metodologías para extender la validación experimental de la máquina eléctrica proporcionando información para evaluar el rendimiento del motor. Esta tesis doctoral ha sido desarrollada con un convenio de colaboración entre la Universidad Politécnica de Cataluña UPC y la empresa MIDTAL TALENTOS S.L. La tesis se engloba dentro del plan de Doctorados Industriales 2018 DI 019 impulsado por la Generalitat de Catalunya.Postprint (published version

Water-pumping permanent magnet synchronous motor optimization based on customized torque-speed operating area and performance characteristics

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper presents a novel methodology for optimizing Permanent Magnet Synchronous Motors for Water-Pumping applications. The algorithm is designed to start the optimization process from a predefined torque-speed area, its desired envelope, and the performance characteristics of the motor to be obtained after the optimization process, providing the information in an efficiency map, according to a predefined control strategy (MTPA, MTPV, etc.). This work also implements an image comparison technique based on the structural similarity index to evaluate the objective function.Peer ReviewedPostprint (author's final draft

Detection of inter-turn faults in multi-phase ferrite-PM assisted synchronous reluctance machine

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currentsPeer ReviewedPostprint (published version

PMSM Parameter Estimation for Sensorless FOC based on differential power factor

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksDuring the last years, different methods for identifying permanent magnet synchronous motor (PMSM) parameters have been developed. Such methods allow a better characterization of PMSMs, thus enabling a better control. This article presents a novel PMSM parameter estimation method based on the differential power factor due to the harmonic distortion, which allows the identification of the motor parameters from data acquisitions representing the entire torque-speed range. This method does not require measuring any geometric parameters, thus avoiding motor disassembly, or prior knowledge of the applied field oriented control (FOC) strategy. It also enables identifying the current, voltage, and dq components of the flux linkage without knowing the rotor position. The proposed method is based on a dq electrical model that considers the harmonic components of the electrical magnitudes. It avoids to apply any optimization technique, thus requiring a low computational burden. The method is first validated experimentally by comparing the identified dq current space vector against the acquired one using a resolver associated with a commercial drive. Finally, it is further validated by using a second PMSM associated with a sensorless drive, comparing the identified dq inductances with ground truth data obtained by a validated method.Peer ReviewedPostprint (author's final draft

Customized PMSM design and optimization methodology for water pumping applications

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe need to reduce water pumps size to achieve compact designs adapted to multiple working points opens new fields of study. PMSMs are the preferred choice due to outstanding torque-speed range capabilities. This paper presents a methodology to design and optimize PMSMs by defining the desired torque-speed-efficiency map, adapting its performance to the hydraulic characteristics of the water pump. Once the hydraulic efficiency is known, an initial PMSM reference torque-speed-efficiency map is defined according to the objective motor performance, including the distribution of power losses and the power rating of the selected application. The designer has full freedom to define the efficiency levels and distribution along the torque-speed map. The design optimization algorithm achieves the PMSM characteristics which adjust as much as possible to the defined performance. This methodology uses ultra-fast finite element analysis by applying magneto-static computations and a time-space conversion to compute the iron losses, reducing the computational requirements. The torque-speed-efficiency map is calculated by applying a direct-quadrature electrical model. The objective function uses a novel image comparison technique that allows comparing the similarity between the objective and optimized maps. The methodology is validated experimentally by designing and testing a PMSM adapted to a real WP application.Peer ReviewedPostprint (author's final draft

PMSM Torque-speed-efficiency map evaluation from parameter estimation based on the stand still test

During the last decades, a wide variety of methods to estimate permanent magnet synchronous motor (PMSM) performance have been developed. These methodologies have several advantages over conventional procedures, saving time and economic costs. This paper presents a new methodology to estimate the PMSM torque-speed-efficiency map based on the blocked rotor test using a single-phase voltage source. The methodology identifies the stator flux linkage depending on the current magnitude and angle while providing a detailed estimation of the iron losses. The torque-speed-efficiency map provides detailed information of the motor efficiency along its operating region, including the nominal conditions and the maximum power envelope. The proposed methodology does not require knowing the geometry of the machine to perform any load test, and it also avoids using expensive measurement devices and a complex experimental setup. Moreover, the proposed method allows the PMSM performance to be reproduced by applying different control strategies, which is useful when testing different drives. The method does not require the application of any optimization algorithm, thus simplifying and speeding up the process to determine the performance. Experimental validation is carried out by comparing motor performances obtained through the proposed method with those obtained by means of a conventional experimental method and against finite element analysis (FEA).Peer ReviewedPostprint (published version

Water-pumping permanent magnet synchronous motor optimization based on customized torque-speed operating area and performance characteristics

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper presents a novel methodology for optimizing Permanent Magnet Synchronous Motors for Water-Pumping applications. The algorithm is designed to start the optimization process from a predefined torque-speed area, its desired envelope, and the performance characteristics of the motor to be obtained after the optimization process, providing the information in an efficiency map, according to a predefined control strategy (MTPA, MTPV, etc.). This work also implements an image comparison technique based on the structural similarity index to evaluate the objective function.Peer Reviewe

Detection of inter-turn faults in multi-phase ferrite-PM assisted synchronous reluctance machine

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currentsPeer Reviewe

PMSM design for achieving a target torque-speed-efficiency map

©2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.During the last years, the requirements for a fast and reliable design of electrical machines by applying optimization methods using finite element analysis (FEA), has become a subject of study. Due to their capabilities, permanent magnet synchronous machines (PMSMs) have become the preference choice for many applications, including electric vehicles (EVs) propulsion, water-pumping, robotics, or renewable power generation among others. This paper presents a novel methodology for designing and optimizing PMSMs using the torque-speed-efficiency map. The design-optimization algorithm requires as input, the torque-speed-efficiency map of the target motor, to define the required performance for the given application. The objective is to find the motor geometry which better approximates the target torque-speed-efficiency map. The PMSM is evaluated by using magneto-static FEA combined with direct-quadrature (d-q) electrical modeling, thus greatly reducing the computational burden when compared to conventional time-dependent FEA methods. The magneto-static FEA method calculates iron losses taking into account the magnetic flux density harmonic content by applying a time-space conversion approach. The design-optimization process takes into account the control strategy as well as losses separation, which is validated by using the public experimental data of the Toyota Prius and Camry PMSMs.The authors would like to thank the support of the Generalitat de Catalunya under the Industrial Doctorate 2018 DI 004 and 2017SGR0967 projects, as well as the Spanish Ministry of Economy and Competitiveness under the project TRA2016-80472-R.Peer ReviewedPostprint (author's final draft

Detection of partial demagnetization faults in five-phase permanent magnet assisted synchronous reluctance machines

This paper analyzes partial demagnetization faults in a five-phase permanent magnet assisted synchronous reluctance motor (fPMa-SynRM) incorporating ferrite permanent magnets (PMs). These faults are relevant because of the application of field weakening, or due to high operating temperatures or short circuit currents, the PMs can become irreversibly demagnetized, thus affecting the performance and safe operation of the machine. This paper proposes fault indicators to detect such fault modes with low demagnetization levels between 5.0% to 16.7% relative demagnetization. Four partial demagnetization fault detection methods are tested, which are based on the analysis of the harmonic content of the electromotive force (EMF) under no load conditions, the harmonic content of the line currents, the harmonic content of the zero-sequence voltage component (ZSVC) and the analysis of the power factor (PF). This work also compares the sensitivity and performance of the proposed detection methods. According to the fault indicators proposed in this paper, the results show that the analysis of the EMF, ZSVC and PF are the most sensitive detection methods. Experimental results are presented to validate finite element analysis (FEA) simulations.Peer ReviewedPostprint (published version