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An interturn short-circuit in the stator windings can lead to the breakdown of electrical machines. In the case of induction machines, several fault detection methods and faulted models have been developed in the recent decades. These models differ mainly in how the leakage inductances of the faulted winding are modeled. This work provides a generalized model for interturn short-circuit faults, using different assumptions for the leakage inductances. The model is validated with experimental results for an exhaustive set of fault parameters, and the leakage inductances influence is analyzed. Moreover, the model is used to analyze the drawbacks of the negative-sequence fundamental current as a traditional fault signature. A high-frequency injection method for converter-fed machines is presented to overcome these limits. The proposed fault signature is the negative-sequence current at the injection frequency and it is evaluated experimentally at different operating conditions. The fault severity and its location are proved to be related to the proposed fault signature., Not duplicate with DiVA 1657021QC 20230202

Electric drives are widely used in industry, where they are also part of the plant communication architecture. This architecture is challenged by the Industry 4.0 initiative that aims to make the devices in industrial plants more interconnected and with additional functionalities. These changes heavily affect electric drives, and thus their future role in industrial networks should be investigated. The first part of this work analyzes two examples of additional functionalities for electric drives from a network system perspective: condition monitoring and multi-drive systems. The suitability of the industrial communication protocols is evaluated for both application cases. Condition monitoring and multi-drive systems are further analyzed considering EtherCAT and CAN networks. A performance model is proposed to control multi-drive systems with EtherCAT, where condition monitoring data is also considered. The transmission of bulk data originated by condition monitoring methods is considered in the traditional industrial fieldbus CAN, and an extended schedulability analysis is proposed. The second part of this work deals with the implementation of condition monitoring algorithms for the stator winding insulation in electric machines. Initially, interturn short-circuit faults in induction motors are investigated. An analytical and a finite-element model are developed and experimentally validated by means of a motor prototype with tapped windings, which can emulate the interturn faults. Fault detection methods based on the negative-sequence current and the rotor slot harmonics are analyzed both theoretically and experimentally. The stator winding insulation condition, including the groundwall insulation, is also considered for condition monitoring utilizing the MHz-range oscillations in the stator currents after switching transitions. Such oscillations depend on the parasitic capacitances of the stator winding, which in turn relate to the insulation condition. In order t, QC 20220510

This paper presents the implementation procedure of three Pulse Width Modulation (PWM) techniques and a closed-loop motor control method using a model-based design approach. The implemented PWM techniques are the Sinusoidal Pulse Width Modulation (SPWM), Space Vector Pulse Width Modulation (SVPWM), and Selective Harmonic Elimination Pulse Width Modulation (SHEPWM), whereas the closed-loop motor control method is the Direct Torque Control (DTC). These techniques are implemented using a ZedBoard development board which contains a System on a Chip (SoC) Xilinx Zynq-7000. The procedure of implementing these techniques on the ZedBoard and required considerations are discussed. The model-based design approach facilitates rapid implementation without prior knowledge of HDL and ARM programming, which makes it advantageous for students and research work. To verify the integrity of the implemented designs, the ZedBoard is used to control an induction machine (IM), and the results are presented., QC 20230206

Condition monitoring of the insulation health of electric machines is usually performed with offline tests. In recent years, online condition monitoring methods for the groundwall insulation have been introduced. The majority of these works are based on leakage current measurements, requiring additional equipment compared to the standard one in converters. The condition monitoring method in this work instead relies on the high-frequency ringing of stator currents occurring after a converter switching transition. This work evaluates the method experimentally in a randomly-wound stator winding of an induction machine prototype equipped with taps. The insulation condition change is forced by inserting external capacitors. Through the analysis of different metrics for the health monitoring and a detailed discussion of the hardware and software requirements for an electric drive, a viable way forward for the practical implementation of the approach is proposed., Not duplicate with DiVA 1656961QC 20230112

Condition monitoring of the insulation health of electric machines is usually performed with offline tests. In recent years, online condition monitoring methods for the groundwall insulation have been introduced. The majority of these works are based on leakage current measurements, requiring additional equipment compared to the standard one in converters. The condition monitoring method in this work instead relies on the high-frequency ringing of stator currents occurring after a converter switching transition. This work evaluates the method experimentally in a randomly-wound stator winding of an induction machine prototype equipped with taps. The insulation condition change is forced by inserting external capacitors. Through the analysis of different metrics for the health monitoring and a detailed discussion of the hardware and software requirements for an electric drive, a viable way forward for the practical implementation of the approach is proposed., QC 20230117

QC 20220510Submitted to IEEE transactions on energy conversion, ISSN 0885-8969, EISSN 1558-0059

QC 20220510submitted for publication in IEEE Transactions on Industrial Electronics

QC 20220510

As the working horse in the industrial world, induction motors are widely applied in many important areas. Hence, it is crucial to investigate the fault operation conditions that would cause their deterioration of working performance or even failures, such as the inter-turn short-circuit (ITSC) fault. This study aims at analyzing the extra generated loss and induced thermal response in an 11kW induction motor under such a fault scenario. Specifically, a new finite element model with separated conductors in the stator slot is built, which characterizes the physics of ITSC fault propagation at different stages by varying the numbers of shorted conductors. In addition, the ITSC fault is implemented in different positions of the stator slots and the consequent motor temperature distributions are analyzed as well., QC 20230614

Travelling wave (TW) based protection functions, which process the time of arrival of TWs, require high sampling rates in the range of hundreds of kilohertz to several megahertz. In digital substations merging units (MU) publish the sampled values of current and voltage signals on process-level networks. However, publishing these highly sampled signals for TW-based protection functions limits severely the number of MUs in a process-level network due to the significant increase of communication load. To circumvent this problem, distributed signal processing units (DSPU) extract directly the necessary signal features and publish these at a lower publishing rate in order to decrease the communication load. This paper provides an mathematical analysis on the scalable integration of DSPUs in deterministic process-level networks based on the High-availability Seamless Redundancy (HSR) protocol, time-aware network nodes and traffic scheduling. It is shown that the distributed signal processing architecture provides a scalable integration of high sampling rate measurements for TW-based protection functions. Lastly the analytical model has been validated through a discrete-event simulation., Part of proceedings: ISBN 978-1-6654-1502-6QC 20220816

Industrial Controller Area Networks (CANs) are traditionally responsible for transmitting status and control information from and to local controllers. However, with the advances of electronics, end-nodes are capable of performing more complex operations, such as monitoring the state of the device and optimizing its operation. As a consequence, CANs should be used for the transmission of heterogeneous message types. In this work we evaluate how CANs can share their transmission resources and collect also bulk data, in addition to serving the existing controller traffic. We derive the constraints bulk data transmission needs to fulfill to ensure the robust and timely transmission of controller traffic, and propose scheduling solutions that ensure fast data delivery. Our results demonstrate that bulk data transmission is possible, unless the networks is already highly loaded, and fast delivery can be achieved even with simple transceiver hardware., ISBN: 978-1-7281-6389-5QC 20201029

—Multi-drive systems and condition monitoring could benefit from a larger exchange of information between the electric drives and the industrial network. This is favored by the Industry 4.0 and the Industrial Internet initiatives together witht he emergence of high-speed industrial networks. This paper investigates how recent industrial communication protocols can handle the emerging diversity of service requirements. After a brief overview of multi-drive system and condition monitoring applications for networked electric drives, the paper provides a quantitative evaluation of the performance of EtherCAT-based network of electric drives, supporting both dynamic control and condition monitoring., QC 20201027

A power system (1) comprising: an n-phase electrical machine (M), where n>3, N power modules, where N≤n, each power module comprising a plurality of power electronic switches, each power module being configured to power a respective subset of unique phases of the n phases, a primary control unit (7a) configured to control all of the N power modules in normal operation of the primary control unit (7a), and a redundant control unit (7b) configured to control all of the N power modules only in case the primary control unit (7a) is subjected to a fault., QC 20210210

Industrial automation has been recently challenged by new initiatives such as Industry 4.0, which promises higher connectivity between the devices in an industrial plant. The goal of this work is to discuss how electric drives, widely employed in industry, could benefit from this increased connectivity. Specific applications, such as condition monitoring and multi drive systems, are considered to show the advantages of the industrial network presence, combined with the introduction of new data driven methods. Moreover, the status of industrial communication technologies is depicted, and their suitability for condition monitoring and multi-drive systems applications is described., QC 20190214

In this paper, a novel dv/dt filter is presented targeted for 100-kW to 1-MW voltage source converters using silicon carbide (SiC) power devices. This concept uses the stray inductance between the power device and the converter output as a filter component in combination with an additional small RC-link. Hence, a lossy, bulky, and costly filter inductor is avoided and the resulting output dv/dt is limited to 5-10 kV/mu s independent of the output current and switching speed of the SiC devices. As a consequence, loads with dv/dt constraints, e.g., motor drives can be fed from SiC devices enabling full utilization of their high switching speed. Moreover, a filter-model is proposed for the selection of filter component values for a certain dv/dt requirement. Finally, results are shown using a 300-A 1700-V SiC metal-oxide-semiconductor field-effect transistor (MOSFET). These results show that the converter output dv/dt can be limited to 7.5 kV/mu s even though values up to 47 kV/mu s weremeasured across the SiC MOSFET module. Hence, the total switching losses, including the filter losses, are verified to be three times lower compared to when the MOSFET dv/dt was slowed down by adjusting the gate driver., QC 20180516

This study proposes a model-based control strategy for flux weakening operation of a synchronous reluctance machine, with a methodology that is extendible to any synchronous machine. The strategy leverages in the presence of digital non-linear models that describe the relation between currents and flux linkages in the machine. Such models are usually needed for conventional maximum-torque-per-ampere control and sensorless control, but here they are exploited to achieve flux-weakening operation without the need of flux weakening regulators, ensuring a seamless transition between the operating regions of the machine. The external voltage regulation loop for flux weakening is thus eliminated and substituted by a combination of look-up tables and binary searches, which are executed within one digital control period and which generate the required current and voltage references that fulfil the drive limitations. The method can also be coupled with mechanisms to compensate for magnetic parameter inaccuracies, to achieve an accurate tracking of the reference torque. The proposed solution is simulated and validated in a laboratory test bench on an 11 kW synchronous reluctance machine., QC 20190528

This paper provides details regarding the design of a self-powered supply used with a hybrid DC switch, and its control system. The power supply was configured to accept the voltage over the contacts of the DC switch as its source and deliver a stable 5 V output rail. This output voltage was used to power a microcontroller which generated a sequence of control pulses for thyristors used in the hybrid switch. These thyristors were used to charge and discharge a resonant circuit which ultimately provided a counter current capable of extinguishing an arc which occurred over the contacts of the DC switch when interrupting DC current., QC 20181126

A method of detecting a permanent magnet rotor of a synchronous machine, includes: injecting a voltage waveform to the stator windings of the synchronous machine, measuring two phase currents in the stator winding, transforming the two phase currents to a rotor reference frame to obtain a current waveform, sampling the current waveform to obtain positive and negative portion values, constructing first and second periodic waveforms by using the sampled positive and negative portion values, performing a frequency analysis of a first and second spectrums of the periodic waveforms, and determining whether a permanent magnet is present in the synchronous machine based on the spectrums., QC 20191014Also published as: CN108233780 (A), EP3337031 (A1), EP3337031 (B1), US2018167010 (A1)

This paper proposes a model-based current/torque control strategy for synchronous machines, where the magnetic model mismatches are compensated in real time and the flux weakening operation is obtained without the need of an external voltage regulation loop. Starting from an initial (and potentially wrong) knowledge of the non-linear current-to-flux linkage relation in the form of a look-up-table, a combination of feedforward actions, compensating mechanisms and binary searches are used to achieve the target during real-time operation. The algorithm is implemented in a laboratory test bench and successfully verified with experiments on an 11-kW synchronous reluctance machine, proving the feasibility of the proposed approach., QC 20180921

The present disclosure relates to a method of controlling a synchronous machine (M) by means of an electrical drive (11), wherein the method comprises: a) obtaining a current reference vector for a torque reference, from at least one current look-up table, which at least one current look-up table describes relations between currents and torques under a plurality of conditions for the synchronous machine, and obtaining a flux linkage vector for the current reference vector from a flux linkage look-up table describing relations between currents and flux linkages, b) determining an adjustment part voltage vector by means of a regulator, based on a difference between the current reference vector and a measured current ( i dq ), c) determining a flux linkage adjustment vector and a torque reference error based on the adjustment part voltage vector and on the measured current, d) generating a compensated torque reference by summing the torque reference and the torque reference error, e) obtaining a new current reference vector for the compensated torque reference, from the at least one current look-up table, and obtaining a new flux linkage vector for the new current reference vector from the flux linkage look-up table, f) determining a voltage reference vector based on the new current reference vector and on the sum of the new flux linkage vector and the flux linkage adjustment vector by means of a model describing the dynamics of the synchronous machine, , and g) controlling the synchronous machine by means of the electrical drive based on the adjusted voltage reference vector., QC 20210222

The paper analyses a combined current model-voltage model estimator for flux linkages in permanent magnet synchronous machines, with the capability of converging to exact flux estimation even in presence of mismatches because of magnetic saturation. As a trend in next-generation electric drives, the whole algorithm, including both the flux estimator and the standard field-oriented control, has been implemented in a field-programmable gate array (FPGA) chip. Simulations and experimental tests, along with some figures for the FPGA selection, have been included in the study., QC 20180921

This work discusses an online stator resistance estimation method for synchronous machines. Multiple improvements are provided with respect to a similar method already been used for induction machines. The method is based on the temporary injection of a DC voltage in the machine phases during normal operation. The stator resistance estimation is obtained by means of the Ohm's law. The proposed scheme works entirely in the stator fixed reference frame, without the need of any machine parameter. The selection of the DC injection level is discussed, as well as the countermeasures for reducing the spurious harmonics appearing in the currents and the torque when the machine is speed- and current-regulated. In particular, minimum electric loss and minimum torque ripple due to the injection is achieved. Moreover, as an alternative to conventional low-pass filtering of the measured signals, it is shown that the resistance estimation can be obtained by averaging the signals over few electric periods. Experiments prove the validity of the proposed approach., QC 20180921

This study presents a self-commissioning procedure for the estimation of the flux linkage curves of synchronous reluctance machines. The procedure exploits a quasi-standstill condition obtained by imposing fast torque oscillations. The flux linkage is calculated by means of a pure integration of the voltages and currents. With respect to the existing procedures, the proposed one tackles the problem of the limited knowledge of the core losses in the electrical machine, which is shown to induce erroneous estimation results for the case under investigation. A theoretical analysis supported by extensive laboratory measurements is shown, proving the effectiveness of the proposed approach., QC 20180921

QC 20170531

QCR 20210802