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Although there is a growing interest in developing fast charging methods to enhance the Electric Vehicles’ appeal, the main energy supply is still the single-phase outlet. While single-phase charging may be simpler than three-phase, there are challenges in the integration of the propulsion and charging systems without adding inductive grid filters. Such integration would bring benefits like the simplification and reduction of components, costs, volume or weight. This can be achieved by using the windings of the propulsion machine as grid filters, but the use of the electric motor as a grid inductive filter leads to the generation of pulsating torque during the charging state. This translates into vibration, noise and eventually, damage to the motor and other components of the system. In this work, the authors propose a control strategy that considerably reduces the peaks of pulsating torque generated in any rotor position while using the machine wingdings as filter. Simulation tests have been carried out to validate the control strategy, taking into account the system efficiency. Finally, experiments are conducted to prove that the reduction of the torque pulsation is achieved.

IEEE Energy Conversion Congress and Exposition, ECCE 2022 (14th. 2022. Detroit, USA)

This work was supported by the Government of the Principality of Asturias under Project AYUD/2021/50988.

IEEE Energy Conversion Congress and Exposition, ECCE (14th. 2022. Detroit, USA)

IEEE Energy Conversion Congress and Exposition, ECCE (14th. 2022. Detroit, USA)

IEEE Energy Conversion Congress and Exposition, ECCE (14th. 2022. Detroit, USA), This work was supported in part by the Research, Technological, Development and Innovation Programs of the Spanish Ministry of Science and Innovation, under grant PID2019-106057RB-I00.

Broken rotor bar detection in a line-connected induction machine using complex wavelets to analyze the stator currents during startup transients was presented in this work. These wavelets allow for the accurate detection of fault related components in the stator current complex vector indicative of damaged rotors. In comparison with standard wavelet based methods, the wavelet design is made following a well defined procedure. Because of this, limits for the scale and time translation parameters of the transform are easily established, reducing the computational requirements of the transformation. In addition, interpretation of the results of the wavelet transform is physically insightful. Experimental results confirm the effectiveness of the method in detecting damaged rotor bars.

IEEE Energy Conversion Congress and Exposition, ECCE (13th. 2021. Virtual), This work was supported in part by the Research, Technological Development and Innovation Programs of the Spanish Ministry of Science and Innovation, under grant PID2019-106057RB-I00.

Modeling of convection heat-transfer at the end-windings for thermal networks using lumped-parameters has been widely discussed in the literature. Unfortunately, the resulting coefficients are highly influenced by the end-winding shape, the area in the vicinity of the end-windings, the cooling method of this region (if any), as well by the size and power of the machine. This makes it extremely difficult for the designer to choose a suitable coefficient for the thermal analysis during the design stage of an electric motor. A methodology to obtain the end-windings convection heat-transfer coefficients for fractional-slot concentrated winding permanent-magnet synchronous motors is proposed in this article. Machine designs with both internal and external rotors will be considered. The experimental tests required for the model characterization are described in detail. In this article, general expressions of the convection heat-transfer coefficients between the end-windings and the housing end-caps are proposed for both internal and external rotor designs. Differences observed with the results reported in the literature are also discussed.

IEEE Energy Conversion Congress and Exposition, ECCE (13th. 2021. Virtual), This work was supported in part by the Research, Technological Development and Innovation Programs of the Spanish Ministry of Science and Innovation, under grant PID2019-106057RB-I00.

International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) (60th. 2019. Riga, Latvia), The research was performed with the support of the Russian Science Foundation grant (project 15-19-20057).

Torque estimation in permanent magnet synchronous machines and synchronous reluctance machines is required in many applications. Torque produced by a permanent magnet synchronous machine depends on the permanent magnets&rsquo, flux and d q -axes inductances, whereas torque in synchronous reluctance machines depends on the d q -axes inductances. Consequently, precise knowledge of these parameters is required for proper torque estimation. The use of high frequency signal both for permanent magnets&rsquo, flux and d q -axes inductances estimation has been recently shown to be a viable option. This paper reviews the physical principles, implementation and performance of high-frequency signal injection based torque estimation for permanent magnet synchronous machines and synchronous reluctance machines.

Small grid-tied wind turbines based on permanent magnet generators often use a cost-effective power converter topology consisting of a passive rectifier, a boost converter, and an H-bridge inverter. Speed or position sensors are rarely used due to cost issues. Model-based estimators relying on electrical magnitudes are used instead. However, such estimators are parameter sensitive, which limit their accuracy. Further concerns arise if these parameters change with the operating condition of the machine, mainly due to temperature. Speed sensorless control using the rectifier voltage ripple is analyzed in this paper. This technique provides good dynamic response and does not depend on machine parameters. Simulations are provided for speed and power tracking comparison with an accurate model-based speed estimation method operating at non-rated parameters. They show the speed accuracy and power tracking capability of the proposed method are similar to that provided by a speed sensor. This is translated into a 0.9% power increase when the model-based speed estimator shows 9% of error. Experimental results are carried out to test the effect of current and temperature in the estimation, showing temperature insensitivity and some distortion due to fast current transients. A speed estimation accuracy of zero mean error and 1.7% standard error is experimentally obtained in the regular operation of the wind turbine.

Parallel controller structures are often used for the control of harmonic components in those power converters, including harmonic-compensation functions. The controlled signal can be distorted during the voltage saturation of the power converter output. This article proposes an implementation of the realizable reference antiwindup technique suitable for parallel controllers in multiple reference frames. The proposed implementation is simple and does not require a particular type of controllers nor special controller arrangements. The proposed implementation can be used for any kind of linear controller structure regardless of the variables being controlled. In the context of harmonic current controllers, the antiwindup implementation allows separating the harmonic controller outputs for canceling or decreasing them during steady-state saturation to improve the waveform quality. Different saturation options are analyzed for the inner loop current controller of grid-forming converter applications.

Accurate, high bandwidth current control is a requirement for high performance vector controlled AC drives. Synchronous PI current regulators are the preferred solution for this purpose. Design and operation principles of synchronous PI current regulators are well established. However, there are a number of issues that must be considered, especially when the drive must operate at high synchronous frequencies, including regulator design, effects due to discretization and the associated delays, voltage constraints and current sampling issues among other. Inadmissible degradation of the current regulator performance and consequently of the drive can occur otherwise.

Online monitoring and diagnostics of permanent magnet synchronous motors (PMSMs) is becoming important with the increasing demand in PMSM applications. Most of the research effort focuses on motor current signature analysis (MCSA) as it can provide remote, online monitoring at low cost. However, all types of defects that produce asymmetries in the PMSM rotor or load produce identical rotor rotational frequency components. This is a serious limitation when applying MCSA since it can produce false indications and degrade the sensitivity of fault detection. The requirement of complex time–frequency analysis techniques is another limitation of MCSA for applications with speed variations. In this paper, the feasibility of using analog Hall sensor signals to complement MCSA for detection and classification of rotor- and load-related defects is investigated. It is shown that Hall sensors installed in machines for initial rotor position estimation can be used with minimal hardware modifications to detect and classify signatures produced by the rotor and load for cases where MCSA fails, even during transient conditions. Experimental testing performed on an interior permanent magnet synchronous motor (IPMSM) under eccentricity, local demagnetization, and load unbalance conditions shows that the reliability and sensitivity of fault detection in PMSM systems can be improved at low added cost.

International Symposium on Power Electronics (Ee) (20th. 2019. Novi Sad, Serbia), The research was performed with the support of the Russian Science Foundation grant (project 15-19-20057).

International Workshop on Electric Drives: Improvement in Efficiency of Electric Drives (IWED) (26th, 2019, Moscow, Russia), This research was performed with the support of the Russian Science Foundation grant (project 15-19-20057)

Negative d -axis current injection used in interior permanent magnet synchronous machines (PMSMs) weakens the permanent magnets’ (PMs) flux, eventually increasing the PMs losses and reduces, therefore, the machine efficiency. Several studies have reported that the increase in the air gap flux harmonic content as the primary reason for the PM losses increase in flux weakening operation, disregarding PM properties variation with the magnetization state (MS) due to PM magnetoresistive effect. This paper analyzes the variation of PM losses with the MS and flux weakening current, the target being threefold: a better understanding of PM losses production mechanisms; to analyze the impact of MS on the thermal behavior of the machine; use this knowledge to improve the machine design.

Rotor eccentricity and local demagnetization in permanent magnet synchronous motors (PMSMs) increase unbalanced magnetic pull and motor vibration resulting in accelerated aging of motor components. If the asymmetry in the rotor remains undetected, it can increase in severity, and increase the risk of stator–rotor contact, which causes forced outage of the motor and driven process. Detection of PMSM rotor asymmetry currently relies on offline testing and online vibration/current spectrum analysis. However, they are inconvenient or cannot provide reliable detection of rotor faults for all PMSM designs. In this paper, the feasibility of using the signals from analog Hall-effect field sensors for detecting eccentricity and local demagnetization is investigated. It is shown that Hall sensors present in machines for motion control can be used for directly measuring the variation in the flux inside the motor due to rotor magnetic asymmetry with minimal hardware modifications. Three-dimensional finite-element analysis and experimental results performed on an interior PMSM show that the proposed method can provide sensitive and reliable detection of dynamic/mixed eccentricity and local PM demagnetization.

Workshop on Control and Modeling for Power Electronics, COMPEL (9th, 2028, Padua), This work was supported by the Spanish Government under projects DPI2014-56358-JIN. It was also supported by the European Commission under FP7 Large Project, grant UE-14-SPEED-604057.

Torque production capability of permanent magnet synchronous machines (PMSMs) depends on the permanent magnet (PM) magnetization state (MS). MS is a function of PM initial magnetization level, which decreases as temperature increases. Furthermore, excessive PM temperature can produce irreversible PM demagnetization. PM MS and temperature measurement/estimation is therefore important both for torque control and monitoring purposes. The injection of a high-frequency (HF) signal in the stator windings has been shown to be a viable option for temperature and MS estimation. This technique estimates the PM temperature or/and MS from the variation of the stator reflected PM HF resistance. However, since PM HF resistance is affected by both PM temperature and MS due to magnetoresistive effect, separating both effects is not trivial. This paper studies the effect of magnetoresistance and temperature on the PM resistivity, the target being twofold: to understand how temperature and MS estimation methods interfere with each other, and to further use this knowledge for the development of methods to be able to estimate the magnet temperature and MS simultaneously.

International Symposium on Sensorless Control for Electrical Drives, SLED (9th, 2018, Helsinki), This work was supported in part by the Spanish Ministry of Economy and Competitiveness under grant MINECO-17-ENE2016-80047-R. M. Martinez, D. Reigosa, D. Fernández, J. M. Guerrero and F. Briz are with the Department of Electrical, Computer & System Engineering, University of Oviedo, Campus de Gijón, 33204, Gijón, Spain.

IEEE Energy Conversion Congress and Exposition (ECCE) (10th, 2018, Portland), This work was supported in part by the Research, Technological Development and Innovation Programs of the Spanish Ministry Economy and Competitiveness, under grant MINECO-17-ENE2016-80047-R.

This paper proposes a new predictive torque control algorithm for synchronous reluctance motor drives with the ability to track online the maximum torque per ampere trajectory. An additional term is included in the cost function of the predictive control algorithm which uses an adaptive weighting factor to improve the dynamic behavior of the drive system. As the derivative of torque with respect to the current angle depends on the values of the apparent and incremental inductances, the apparent inductances are estimated online based on the values of the flux linkage and current components while the incremental inductances are estimated using a recursive least squares (RLS) algorithm. Experimental results validate the proposed control algorithm and demonstrate a remarkable performance both in steady-state and during transients, as well as a reduction of the current ripple and audible noise. info:eu-repo/semantics/publishedVersion

Nonlinear loads (NLLs) in three-phase systems are known to produce current harmonics at −5, 7, −11, 13,… times the fundamental frequency. However, harmonics of the same frequencies are induced in microgrid voltage thereby reducing the power quality. Dedicated equipment, such as active power filters, can be used to compensate the microgrid harmonics. Alternatively, each distributed generation (DG) unit present in the microgrid can also be used for the same. The use of the virtual admittance concept combined with a proportional integral with resonant controller (PI-RES) control structure has previously been proposed as a harmonic compensation sharing strategy when multiple DGs operate in parallel. The drawback of this methodology is that a large number of RES controllers might be required to compensate for all the harmonic components induced by NLLs, increasing the tuning complexity as well as the execution time. This paper proposes the combined use of virtual admittance control loop and repetitive controller (RC) for harmonic compensation. The main advantage of the proposed method is that only one RC is required to compensate for all the harmonic components, significantly reducing the computational burden and the design complexity. The dynamic performance of the whole system is tested under variable NLL.

The use of the virtual admittance concept for harmonic and/or unbalance compensation in microgrids when multiple inverters operate in parallel is proposed in this paper. The virtual impedance concept has been traditionally used for these purposes. However, one drawback of the virtual impedance is that it can only be applied to distributed generation (DG) units operating in voltage control mode (VSI-VCM), but is not applicable to DG units working in current control mode (e.g. current regulated voltage source inverters, VSI-CCM or current source inverters, CSIs. Contrary to this, the proposed method can be used in any converter topology and control mode, including VSI-CCM, VSI-VCM and CSI.

Implementation of the control of a Solid State Transformer (SST) is described in this paper. The SST topology considered is derived from a Modular Multilevel Converter (MMC), in which the cells have the capability to transfer (inject or drain) power. The MMC is combined with an isolation stage formed by Dual Active Bridges (DABs) and a DC/AC power converter. The resulting modular multiport power converter can connect both high voltage and low voltage AC and DC ports, providing isolation between the high voltage and the low voltage terminals, and with full control of the power flow. Implementation of the control of this power converter is not trivial, due to the large amount of power devices and sensors involved, and to the complexity of the control algorithms. Furthermore, the need to provide isolation among the different stages adds further concerns mainly related with cost. This paper discusses the configuration, selection of the required hardware, as well as implementation aspects for the control of the proposed SST topology, This work was supported in part by the Research, Technological Development and Innovation Programs of the Spanish Ministries of Science and Innovation and of Economy and Competitiveness, under grants MICINN- 10-CSD2009- 00046, ENE2013-48727-C2-1-R, DPI2013-47176-C2-2-R and by the European Commission FP7 Large Project NMP3-LA-2013-604057, under grant UE-14-SPEED-604057

This paper deals with discrete-time models and current control methods for synchronous motors with a magnetically salient rotor structure, such as interior permanent-magnet synchronous motors and synchronous reluctance motors (SyRMs). The dynamic performance of current controllers based on the continuous-time motor model is limited, particularly if the ratio of the sampling frequency to the fundamental frequency is low. An exact closed-form hold-equivalent discrete motor model is derived. The zero-order hold of the stator-voltage input is modeled in stationary coordinates, where it physically is. An analytical discrete-time pole-placement design method for two-degrees-of-freedom proportional–integral current control is proposed. The proposed method is easy to apply: only the desired closed-loop bandwidth and the three motor parameters $(\boldsymbol{R}_\mathbf{s}, \boldsymbol{L}_\mathbf{d}, \boldsymbol{L}_\mathbf{q})$ are required. The robustness of the proposed current control design against parameter errors is analyzed. The controller is experimentally verified using a 6.7-kW SyRM drive.

This paper analyzes the use of pulsating high frequency signal injection for islanding detection purposes. Active islanding detection using high frequency signal injection is an appealing option due to its reduced non-detection zone, reduced cost and ease of implementation. The use of a rotating high frequency signal has been reported and analyzed. However, this method can only be applied to three-phase systems. In this paper, the use of a pulsating high frequency signal injection is proposed. While it uses the same principles as rotating signal injection, it can be applied to both threephase and single-phase systems, T h is w o r k w a s s u p p o r t e d i n p a r t b y the Research, Technological Development and Innovation Programs of the Ministry of Science and Innovation under grant MICINN-10-CSD2009-00046 and by the Personnel Research Training Program funded by the Regional Ministry of Education and Science of the Principality of Asturias under grant BP11-107

High frequency signal injection based methods have been widely investigated for sensorless position/speed control of induction machines (IMs), permanent magnet synchronous machines (PMSMs) and more recently for doubly fed induction generators (DFIGs). When used with IMs and PMSMs, the high frequency signal is injected in the stator windings, an asymmetric (salient) rotor being required for this case. Contrary to this, both stator and rotor terminals are accessible and sensored in DFIGs, being therefore possible to inject the high frequency signal either in the stator or the rotor terminals. As consequence of this, the method can be used even if the machine is non-salient. In the implementation of the method with DFIGs, the high frequency voltage signal is typically injected in the rotor, the high frequency components (voltages of currents) induced in the stator being used for rotor position estimation. A drawback of this alternative is that the method is sensitive to the grid impedance in the stator side, which will be affected by the grid configuration, and is normally unknown. This paper proposes the sensorless control a DFIG injecting the high frequency voltage in the stator side, and using a high frequency current cancellation strategy in the rotor side. The main advantage of the proposed strategy is that the estimated position is independent of the grid characteristics, This work was supported in part by the Research, Technological Development and Innovation Programs of the Ministry of Science and Innovation under grant MICINN-10-CSD2009-00046 and of the Spanish Ministry of Science and Innovation-ERDF under grants MICINN-10- ENE2010-14941 and MICINN-10-IPT-370000-2010-15

This paper analyzes the use of high-frequency signal injection methods for the sensorless control of doubly fed induction generators (DFIGs). High-frequency signal injection methods have been widely investigated for the sensorless control at very low speed and position control of induction machines and permanent-magnet synchronous machines. Most of these methods inject a high-frequency voltage signal in the stator windings, which interacts with the machine asymmetries (saliencies), modulating the resulting stator high-frequency currents, from which the rotor position is estimated. The use of these methods with DFIGs is studied in this paper, with special focus on two distinguishing features compared with the case of other types of three-phase machines: 1) It is feasible to inject the high-frequency signal in the rotor since the rotor windings are accessible; and 2) as a consequence of this, it is possible to use the method with nonsalient machines, This work was supported in part by the Research, Technological Development and Innovation Programs of the Ministry of Science and Innovation under grant MICINN-10-CSD2009-00046 and of the Spanish Ministry of Science and Innovation-ERDF under grants MICINN-10-ENE2010-14941 and MICINN-10-IPT-370000-2010-15

Synchronization is a key issue in distributed power generation and storage (DPGS), fast and accurate estimation of the grid voltage phase angle being requested. Synchronization methods can be roughly divided among a) zero-crossing-methods, b) Phase-Locked-Loop (PLL) and c) Frequency-Locked-Loop (FLL) methods, with PLL implemented in a synchronous reference frame (SRF-PLL) likely being the most popular choice. A drawback of these methods is that, in general, they do not implement harmonic rejection strategies, their performance in polluted networks being therefore compromised; also their implementation and tuning is not straight forward, often being made by trial and error. This paper proposes a pre-filtering based synchronization method using cascaded complex-coefficient-filters (CCCF) and a complex PLL. The CCCF allows selection of the harmonic isolated/rejected, while the CPLL obtains the phase of the positive sequence component of the fundamental voltage needed for synchronization. The proposed method provides high rejection/adaptation capabilities against unbalances, frequency drift and harmonic distortion of the line voltages.