Search

In this paper, the research on mechanical motion rectification-based electromagnetic vibration energy harvesting (MMR-based EMVEH) is reviewed comprehensively. Firstly, the basic principle of MMR based on linear vibration is introduced, and the general design method of MMR is summarized, including the vibration input module and motion transfer module. Secondly, the structure, dynamics, advantages and disadvantages of different types of EMVEH based on magnetic resonance are analyzed, discussed and compared, mainly the motion conversion mechanism. With the same structural parameters, the equivalent electromagnetic damping of the AC motor is 1.5 times that of the DC motor. Thirdly, the common validation method of MMR-based EMVEH is summarized, including simulation, laboratory experiment and field test. According to the experimental results, the energy conversion efficiency of MMR with different configurations is 30–70 %. The power is due to the transmission ratio of the accelerator, ranging from 100 to 102 W. Then, the application scenarios of MMR-based EMVEH are analyzed and discussed, including vehicle suspension, road speed bumps, railway tracks, ocean waves, and human motion. In addition, the difficulties faced by MMR-based EMVEH are also proposed and analyzed under different application scenarios. Finally, the paper addresses the challenges and further investigations. • A review of MMR-based electromagnetic vibration energy harvesting is presented. • Structure, dynamics, features of MVR-based EMVEH are analyzed. • The validation method of MVR-based EMVEH is summarized. • The typical application scenarios of MVR-based EMVEH are summarized. • Challenges, difficulties and future research points in this field are proposed. [ABSTRACT FROM AUTHOR]

The solar water pumping system is one of the brightest applications of solar energy for its environmental and economic advantages. It consists of a photovoltaic panel which converts solar energy into electrical energy to operate a DC or AC motor and a battery bank. The photovoltaic power fluctuation can affect the water pumping system performances. Thus, the photovoltaic power prediction is very important to ensure a balance between the produced energy and the pump requirements. The prediction of the generated power depends on solar irradiation and ambient temperature forecasting. The purpose of this study was to evaluate various methodologies for weather data estimation namely: the empirical models, the feed forward neural network and the adaptive neuro-fuzzy inference system. The simulation results show that the ANFIS model can be successfully used to forecast the photovoltaic power. The predicted energy was used for the solar water pumping management algorithm. • Temperature and solar irradiation forecasts are done for PV power estimation. • Ghouard's empirical model is the best for solar radiation forecasts on sunny days. • Capderou's empirical model is the best for solar radiation forecasts on cloudy days. • The ANFIS outperforms the empirical models and the FFNN in weather data prediction. • Based on the predicted PV power, water pumping management algorithm is done. [ABSTRACT FROM AUTHOR]

The solar water pumping system is one of the brightest applications of solar energy for its environmental and economic advantages. It consists of a photovoltaic panel which converts solar energy into electrical energy to operate a DC or AC motor and a battery bank. The photovoltaic power fluctuation can affect the water pumping system performances. Thus, the photovoltaic power prediction is very important to ensure a balance between the produced energy and the pump requirements. The prediction of the generated power depends on solar irradiation and ambient temperature forecasting. The purpose of this study was to evaluate various methodologies for weather data estimation namely: the empirical models, the feed forward neural network and the adaptive neuro-fuzzy inference system. The simulation results show that the ANFIS model can be successfully used to forecast the photovoltaic power. The predicted energy was used for the solar water pumping management algorithm. • Temperature and solar irradiation forecasts are done for PV power estimation. • Ghouard's empirical model is the best for solar radiation forecasts on sunny days. • Capderou's empirical model is the best for solar radiation forecasts on cloudy days. • The ANFIS outperforms the empirical models and the FFNN in weather data prediction. • Based on the predicted PV power, water pumping management algorithm is done. [ABSTRACT FROM AUTHOR]

In this study, a constant frequency control technique is proposed for improving the overall power efficiency of a squirrel-cage AC induction motor, so that the induction motor can maintain its original operating state under low energy consumption. In this study, a semiconductor component, the Silicon Controlled Rectifier (SCR), was used as the component for adjusting the voltage phase trigger, and a constant frequency control module was developed to trigger the SCR through the output signals. The experiment records the energy consumption of the rated voltage operation of 0.47 kWh in 4 cycles, and the energy consumption of the voltage adjusting operation is 0.402 kWh. The calculated energy saving rate is about 12%. In addition, the power factor (PF) of the tested induction motor was increased from 0.44 to 0.53 at a low load, which is increased by 22.1%, while the PF of the overall low and high load is increased by about 12.9%. This study improves the conversion effect of converting the overall apparent power (kVA) to active power, to verify the energy-saving effect on the modulation of the voltage input of the squirrel-cage AC induction motor. • This study presents a constant speed control technology. • A silicon controlled rectifier (SCR) element was used to modulate the phase angle. • The proposed control theory effectively reduced unnecessary waste of power energy. • The proposed technology effectively reduced overall energy consumption by 12%. [ABSTRACT FROM AUTHOR]

AC induction motors are the most common motors used in industrial motion. They are widely used in industrial applications for its simplicity, rugged design, low-cost, low maintenance and direct connection to an AC power source. One of the faults occurring in induction motor is the rotor bar breakage that may rapidly spread to a functional failure with catastrophic consequences. Despite the low cost of an induction motor, production losses due to a functional failure in the motor may be greater than the cost of the motor itself. Therefore, the cost advantages that can be achieved with predictive maintenance justify research in monitoring techniques that can indicate the evolution of the conditions before a failure occurs. In this paper, we demonstrate a magnetic sensor based on fiber Bragg grating (FBG) and magnetostrictive composite made of Terfenol-D particulates immersed in epoxy resin matrix applied to induction motor to detect rotor broken bars. To the best of our knowledge, this work demonstrates by the first time an FBG based magnetic sensor applied to monitor an induction motor with the capability to distinguish defective bars, whereas at the same time, conventional technique of current signature at low loading levels failed to indicate the motor severity. The obtained results indicate that the Terfenol-D based sensor can be used for purposes of monitoring broken rotor bars in high voltage induction motors, even when the motor is installed in a dangerous atmosphere, due to the insulation provided by the optical fiber sensor. [ABSTRACT FROM AUTHOR]

A novel circuit of Schmitt trigger employing a prototype of dual-X current conveyor transconductance amplifier and one grounded resistor is proposed in this paper. The main focus of the paper is towards the practicality of the proposed Schmitt trigger using the prototype of DXCCTA which is realized using commercially available ICs. The proposed circuit is easily cascadable. Both clockwise and anticlockwise hystereses are achievable simultaneously from the proposed circuit. The threshold levels and amplitudes of output currents are independently and electronically controllable. The non-ideal and parasitic studies of the proposed Schmitt trigger are investigated. Moreover, the application of Schmitt trigger as zero crossing detector is explored which enriches the applicability of the proposed circuit. Experimental results are depicted to verify the proposed Schmitt trigger circuit. Measured results show the good tuning of amplitude of output current for a wide range of 50 µA to 1.5 mA. [ABSTRACT FROM AUTHOR]

The use of prismatic-core High Temperature Reactors (HTRs), has not yet reached commercialisation, as they are few in operation, and mainly developmental in nature. This work examines numerous models for fuel rotation, thus enhancing and further optimising the fuel lifecycle of a generic HTR. Several rotational scenarios were examined both axially and radially, with radial rotations giving rise to the largest in life extension. Included in the model is a complex analysis of how TRistructural-ISOtropic (TRISO) fuel behaves in operando, increasing the reliably of the model in predicting the benefits of fuel rotation. Finally, an economic assessment was undertaken, which indicted that fuel costs could be reduced by 40.3%, further increasing its economic benefit and efficiency. [ABSTRACT FROM AUTHOR]

The poor battery discharging performance and capacity, operated at low temperature, pose a technical barrier limiting their use in electric vehicles. Therefore, the purpose of this paper is proposed to improve the performance of battery at low temperature. And a sinusoidal alternate current (SAC) heating strategy is proposed to heat the battery. The battery is heated fast and uniformly, due to a large amount of heat generated at the inside of battery when sinusoidal alternate current is transited in a battery. Meanwhile, a layered thermal model is established to simulate the heating method. The SAC heating experimental results show that a lower frequency SAC within the scope of 100 Hz can heat battery effectively. And the simulation results show that the temperature error between outer layer of simulation and experimental tested actual surface temperature is no more than 1 °C. After heated by SAC at low temperature (−20 °C) , the battery capacity is promoted 45%. The proposed heating strategy is of great potential for rapidly improving operating performance of electric vehicles in cold weather. Furthermore, the confirmed layered thermal model could be applied to the investigation of lithium-ion battery. [ABSTRACT FROM AUTHOR]

• The Lyapunov stability criterion is used as a control objective in the proposed model predictive control method. • The use of the Lyapunov stability criterion in the optimal control formulation enhances the closed-loop stability. • The proposed method reduces the sensitivity to the deviation from the nominal operating conditions. • The removal of the weighting factors from the feedback loop design enhances the robustness of the system and simplifies the MPC design stage. • Theoretical concepts are experimentally validated using a hardware set setup. This study presents a novel Lyapunov-based model predictive control strategy for a nine-switch inverter-based multi-drive system. The drive system includes two ac motors and a single nine-switch inverter (NSI) that is capable of feeding the multiple induction motors. The model predictive control (MPC) is a popular feedback strategy in ac-drive applications due to its fast dynamic characteristics and the skill of handling multiple control goals. Although the MPC offers a rapid dynamic response to load variations, it suffers from closed-loop instability when the cost function is poorly designed. The unwise choice of the tuning parameters, cost function terms, and control constraints cause instability resulting in poor system performance. In particular, the formulation of the selected objective function greatly impacts the closed-loop stability since it tailors the closed-loop characteristics. A simple penalization of the control goal error in the cost function may not ensure asymptotic stability. Motivated by the MPC stability problem, the cost function is reformulated as a Lyapunov energy function to strengthen the closed-loop stability in this paper. The proposed method selects the control input that meets the Lyapunov stability criterion and applies it to the multi-motor driver. The proposed strategy ensures asymptotic stability and provides a robust motor operation by introducing the Lyapunov control constraints. The proposed feedback strategy is experimentally verified using a lab-scaled hardware test platform. The experimental results demonstrate that the suggested control routine offers an improved steady-state characteristic compared to the conventional MPC method. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

Majority of the electricity used in the industry is consumed by induction motors. Early detection of abnormal cases that occur at the electrical and mechanical parts of these motors is very important for the safe operation of industrial facilities and the decrease of economic losses. In this presented study, the detection of parallel, angular and mixed misalignment fault in inverter fed induction motors has been carried out via the harmonic analysis of the instantaneous power factor signal. Results obtained from experimental studies carried out under different speed and loads indicated that the detection of misalignment fault can be carried out successfully. The presented method can be used effectively without any additional cost since inverter fed motors have both voltage and current sensors. Also online monitoring of induction motors with the suggested method not only improves the motor's performance and longevity but also its efficiency. The main innovative parts of this study is that instantaneous power factor signal was used at the first time for detection of misalignment faults. [ABSTRACT FROM AUTHOR]

• A new ECRH launcher has been developed for the ECRH system capable of steering EC beam in poloidal and toroidal directions. • The poloidal steering is fast and can be done in real time during the plasma discharge. • UHV compatibility and the motion characteristics of the launcher has been tested in a specially designed vacuum chamber. Electron cyclotron resonance heating (ECRH) launcher is an electro-mechanical system mainly consisting of mirrors (flat and profiled), a steering mechanism, a vacuum barrier window and a UHV (Ultra High Vacuum) compatible gate valve which focuses and steers the ECRH beam into plasma. Presently, Steady-state Superconducting Tokamak (SST)-1 ECRH system has a 42 GHz Gyrotron capable of delivering 500 kW of RF power for the maximum duration of 500 ms. A new steerable ECRH launcher has been developed which can steer the EC beam along both poloidal and toroidal directions. The span of mirror movement in poloidal and toroidal directions is ±20° and ±50°, respectively. The poloidal motion of the mirror can be done in real-time during plasma operation and the mirror can be rotated by 20° in 100 ms. Two AC servo motors independently control the mirror movements through an assembly of motion feedthroughs, spur gears and mechanical linkages. The accuracy, repeatability and speed of both the motions have been measured under UHV in a specially designed vacuum chamber. [ABSTRACT FROM AUTHOR]

The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new methodology for diagnosing the stator winding faults in the six-phase induction motor. [•] The methodology uses the xy current trajectory mass center. [•] A theoretical analysis of the six-phase motor healthy and stator fault operation modes. [•] Results are presented to show the applicability of the proposed technique. [Copyright &y& Elsevier]

Abstract: This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response. [ABSTRACT FROM AUTHOR]

Abstract: In this paper an integrated approach for on-line induction motor fault detection and diagnosis is presented. The need to insure a continuous and safety operation for induction motors involves preventive maintenance procedures combined with fault diagnosis techniques. The proposed approach uses an automatic three step algorithm. Firstly, the induction motor stator currents are measured which will give typical patterns that can be used to identify the fault. Secondly, the eigenvectors/eigenvalues of the 3D current referential are computed. Finally the proposed algorithm will discern if the motor is healthy or not and report the extent of the fault. Furthermore this algorithm is able to identify distinct faults (stator winding faults or broken bars). The proposed approach was experimentally implemented and its performance verified on various types of working conditions. [Copyright &y& Elsevier]

Abstract: This paper deals with modeling and performance analysis of the voltage/frequency (V/f) control of induction motor drives. The V/f control, which realizes a low cost and simple design, is advantageous in the middle to high-speed range. Its torque response depends on the electrical time constant of the motor and adjustments of the control parameters are not need. Therefore, V/f control of induction motor is carried out. Space vector pulse width modulation is used for controlling the motor because of including minimum harmonics according to the other PWM techniques. Proportional Integral (PI) controller is used to control speed of induction motor. In this work, optimization of PI coefficients is carried out by Ziegler-Nichols model and Genetic-Adaptive Neuro-Fuzzy Inference System (ANFIS) model. These controllers are applied to drive system with 0.55kW induction motor. A digital signal processor controller (dsPIC30F6010) is used to carry out control applications. The proposed method is compared Ziegler-Nichols model. Experimental results show the effectiveness of the proposed control method. [Copyright &y& Elsevier]

Abstract: The study presents a combined protection approach for induction motors (IMs). To achieve this, the current, voltage, speed and temperature values of the IM were measured with sensors and processed automatically with the developed software in C. The processes were then inserted into a microcontroller. The experimental results have shown that the IM was protected against the possible problems encountered in online operation. The approach presented in this work provides flexibility, accuracy and reliability for smooth protection with the help of the combined protection approach. Moreover, the protection system can easily be applied to larger motors after small modifications in the software developed. It is also expected that the proposed system would provide faster and low cost protection. [Copyright &y& Elsevier]

Abstract: This paper studies the application of independent component analysis (ICA) and support vector machines (SVMs) to detect and diagnose of induction motor faults. The ICA is used for feature extraction and data reduction from original features. The principal components analysis is also applied in feature extraction process for comparison with ICA does. In this paper, the training of the SVMs is carried out using the sequential minimal optimization algorithm and the strategy of multi-class SVMs-based classification is applied to perform the faults identification. Also, the performance of classification process due to the choice of kernel function is presented to show the excellent of characteristic of kernel function. Various scenarios are examined using data sets of vibration and stator current signals from experiments, and the results are compared to get the best performance of classification process. [Copyright &y& Elsevier]

Abstract: The paper proposes an induction motor model for the study of harmonic load flow in balanced and unbalanced conditions. The parameters of this model are obtained from motor manufacturer data and the positive- and negative-sequence equivalent circuits of the single- and double-cage models. An approximate harmonic model based on motor manufacturer data only is also proposed. In addition, the paper includes manufacturer data and the calculated parameters of 36 induction motors of different rated powers. This database is used to analyze the proposed models. [Copyright &y& Elsevier]

Abstract: The developments in the power electronics field have lead to an ever-increasing use of static switching devices to control the torque and speed of ac motors. Invariably, the output voltage and current waveforms of these devices contain numerous harmonics and these harmonics have detrimental effects on the motor performance in form of derating and torque pulsation, especially at low speed. The order and magnitude of these harmonics depend on the design as well as nature of load being supplied. The extensive research has been underway for a long time in order to assess the effects these harmonics have on induction motor performance, and to investigate the various issues related to the use of induction motor to improve the drive performance and reduce the losses. This paper, therefore, presents a comprehensive review of research and developments in the induction motor operation with non-sinusoidal supply waveforms since its inception. Attempts are made to highlight the current and future issues involved in the development of induction motor drive technology to impart good dynamic stability with improved performance. A list of 167 research publications on the subject is also appended for a quick reference. [Copyright &y& Elsevier]

Abstract: Pairing of repulsive particles with large total momentum results in essential relative-motion momentum dependence of the superconducting order parameter with a nodal line crossing the Fermi contour inside kinematically accessible domains of the momentum space. Repulsive interaction potential resulting in the superconducting pairing is reduced to a stepwise one with a degenerate kernel having two eigenvalues of opposite sign. Using such a kind of contact potential approach the self-consistency equation is transformed into a system of two integral equations determining average values of the order parameter inside the subdomains of its constant sign. The solution of this equation system is obtained in the weak coupling limit. [Copyright &y& Elsevier]

In this paper, an on-line efficiency optimization controller is proposed for induction motor drives after a detailed analysis of motor losses. The controller searches for a minimum motor drive input power by continuous variation of a control variable, resulting in a smooth system performance, which is not possible by the conventional stepwise change of the control variable. The search period is short. Thus, the controller can be applied effectively to applications with frequent changes of speed and load. Also, under the proposed controller, more energy saving is achieved. Extensive simulation is performed for the induction motor under the proposed and conventional efficiency optimization controllers. The results prove the superiority of the proposed controller. [Copyright &y& Elsevier]

• This paper exposes two special AC machines adaptable for electric vehicle application. • Their mathematical models are described and defined. • Their corresponding field oriented vector control topology was designed and verified through simulation steps. There has been a rapid adoption of electric vehicles (EVs), and the industry has been looking for the most enhanced traction system to improve performance and reliability. Such specifications are mostly dependent on the magnetic materials for brushless DC or AC machines, and typically EVs are manufactured with those machines. In the past two decades, there have also been improved performance ratings of power electronic devices. On one hand, making possible AC motors more suitable for EVs. On the other hand, it allows further advanced topology circuits to fit machines with two rotors or two stators. This paper shows two configurations of electrical machine control for EVs, discuss the pros and cons, and corresponding mathematical models have been developed in order to enhance a Field Oriented Control (FOC) strategy, which has been analyzed and studied through MATLAB based simulations, allowing novel design based on the analytical models developed by the authors. [Display omitted] [ABSTRACT FROM AUTHOR]

• The AC loss property of stacked REBCO tapes was explained quantitatively from the viewpoint of the demagnetizing coefficient. • The AC loss curve can be scaled by normalizing by the penetration field of the REBCO tapes regardless of the number of stacks. • A method which can easily estimate the AC loss of REBCO tapes with any number of stacks was proposed. The AC loss occurred in REBa 2 Cu 3 O y (REBCO, RE = rare earth elements, Y, Eu, Gd) superconductor is serious problem in AC applications because it may cause a severe temperature rise of superconducting systems. Therefore, it is necessary to understand the AC loss property of REBCO superconducting tape in detail and to reduce that. As AC application such as motor, the tape is mostly stacked into multi-layer. Thus, understanding the relation between the number of the stacked tapes and the AC loss is one of the most important subjects. So far, we confirmed that the AC loss of the n -layer stacked REBCO superconducting tapes decreases to 1/ n of that of 1-layer for the magnitude of the applied external field, B m , below the penetration field, B p , and such property can be explained from the viewpoint of the demagnetizing coefficient. However, the result in that report was only at 50 K and such property was not systematically confirmed at other temperatures. In this study, the AC loss decreasing property owing to stacking tapes for B m below B p was investigated via experiments. Furthermore, such property was considered theoretically from the viewpoint of the demagnetizing coefficient of the stacked REBCO superconducting tapes. Consequently, it was cleared, from theoretical consideration, that the n dependence of the AC loss can be explained quantitatively by the demagnetizing coefficient, and, in order to apply the theory to the experimental results, the stacked tapes have to satisfy the restrictions which are D / w < 0.1 and t / w << 1. Here, D, w and t are the distance between the neighboring superconducting layers, the width and the thickness of the superconducting layer. Moreover, from such AC loss property, it was revealed that the n dependence of B p can be expressed as a power function. Using the results obtained in this study, the AC losses of the stacked tapes can be estimated easily from that of 1-layer tape. [ABSTRACT FROM AUTHOR]

This technical communique illustrates the potentialities of the recently found letter swap connections between the models of AC induction motors (IMs) and (nonsalient-pole surface) permanent magnet synchronous motors (PMSMs): observability and observer design issues for PMSMs are immediately addressed by directly exploring and decoding the logical paths characterizing the recent corresponding analysis for IMs, without re-performing the related analysis/design from the beginning. [ABSTRACT FROM AUTHOR]

This paper presents a review of the three most significant inventions that will enable future ESP installations to be more efficient and use less power while handling extreme well conditions better than today's systems. It will be shown how these revolutionary ideas will expand the application ranges of future ESP systems and why they soon become part of the daily routine. The novel method of making pump stages using powder metallurgy techniques, instead of the universally used sand molded casting, allows producing pump stages with more complex geometries, improved tolerances, and surface finishes. Such stages provide higher pump efficiencies and are dynamically more balanced as well. The conventional ESP motor is a 3-Phase AC induction motor; the permanent magnet motor introduced recently provides 3–4 times greater power in a shorter constructional length. With motor efficiencies above 90% and extremely high power factors, PMMs develop much lower heat. If driving ESP pumps, the required number of pump stages is much reduced and the use of as smaller downhole cables is possible. Therefore, PMMs will surely be the future prime movers for ESP installations providing greater system efficiencies than the AC motors currently used. The recently patented V-Pump can replace the ESP centrifugal pump; it is a helico-axial pump whose rotor and stator are fitted with an extremely big gap. The produced fluid spirals upward in the rotor channels while a fluid seal is created in the radial gap between the rotor and stator. Pump efficiency is not affected by the size of the gap and the pump can easily handle the most detrimental conditions for conventional ESP pumps: high fluid viscosities, extremely high solid concentrations, and high gas-liquid ratios. Having these desirable features, it can be predicted that usage of the V-Pump will become more and more popular in the future. • The continuous evolution of the ESP technology in the last 90 years is presented. • Powder metallurgy in pump stage manufacturing increases the efficiency of ESP systems. • Permanent magnet motors can reduce power costs and increase run lives. • The V-Pump can greatly increase the service life of ESP systems in extreme conditions. [ABSTRACT FROM AUTHOR]

Periodic out-of-round or polygonised wheels were detected on a fleet of high adhesion locomotives operating within South Africa. The polygonised wheels increased the vertical load spectrum of the locomotive resulting in accelerated component failures. During the initial investigation it was found that torsional axle vibration could lead to the polygonisation of the wheels. The torsional vibration of the locomotive axle was confirmed theoretically and experimentally through various physics models and on-track measurements. Based on the results, two potential torsional vibration excitation mechanisms were identified. A link was also established between the torsional vibration frequency, vehicle operating speed and the polygonisation order. Based on the similarities of the two excitation mechanisms a vibration suppression system was considered and tested. A reduction in the torsional vibration amplitude was observed when the suppression system was active. • Periodic wear or polygonisation is caused by torsional resonance of the locomotive axle. • Torsional resonance is excited by self-excited stick-slip and/or AC traction motor harmonics and interharmonics. • Torsional resonance only occurs at high tractive effort or adhesion conditions. • Exponential polygonisation growth is observed after polygonisation initiation. • Active control system suppression can be used to reduce torsional resonance amplitude. [ABSTRACT FROM AUTHOR]