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In this paper, a novel method to design and optimization of a 1.5 kW, 4-pole, 36-slot salient-pole permanent magnet synchronous machine (SPPMSM) based on a three-step skewed pole shoe method to reduce the output torque ripple and the cogging torque is investigated. In the first step, an initial model of the SPPMSM is designed, simulated, and verified through the Finite-Element method (FEM). The simulation results ensure the electromagnetic performance of the initial model of the machine under any operating conditions. Next, a novel method to re-design and optimize the SPPMSM based on a three-step skewed pole shoe shape is presented.. The significant results obtained from the optimized model of the SPPMSM are as: The output average torque and the air gap flux density are increased approximately by 12.65% and 3.33%, respectively compared to the initial design of the SPPMSM. The torque ripple is an important parameter in the design of the machine, and so, is decreased by about 16.03% which is equal to 10.41% in comparison with the initial model which is equal to 12.41%. The cogging torque in the initial model of the SPPMSM is equal to 0.036 N.m and with a 19.44% reduction, in the optimized model, it is 0.029 N.m. And finally, the back-EMF voltage of the SPPMSM is improved by 1.27% compared to the initial design model. [ABSTRACT FROM AUTHOR]

A novel approach to the design of power factor correction (PFC) and torque ripple minimization in a brushless direct current (BLDC) motor drive with a new pulse width modulation (PWM) technique is demonstrated. The drive was designed to have a better power factor (PF) and less torque ripple. On the other hand, the modified Zeta converter is used to enhance the power factor of the proposed system. The modified Zeta converter is operated in discontinuous inductor current mode (DICM) by using a voltage follower technique, which only needs a voltage sensor for power factor correction (PFC) operation and DC-link voltage control. The output voltage of the VSI is determined by switching patterns generated by the PWM-ON-PWM switching strategy, and it reduces the torque ripples. The proposed drive is developed and simulated in a MATLAB/Simulink environment. The power factor of 0.9999 is produced by the PFC modified zeta converter topology and the PWM-ON-PWM scheme reduce the torque ripple in the commutation region by 34.2% as compared with the PWM-ON scheme. This demonstrates the effectiveness of the suggested control method. [ABSTRACT FROM AUTHOR]

Switched reluctance motor (SRM) drive has outstanding features like robust construction, double saliency, fault tolerance capability, and heat withstanding capability. Despite these, torque ripple is an intrinsic characteristic of SRM because of double salient geometry, air gap length, and switching sequence of motor phase currents, making it unsuitable for slick torque and high dynamic performances applications. This paper discusses the novel Torque Sharing Function (TSF) implementation and the flower pollination algorithm-based intelligent controller to minimize the torque ripples in Switched Reluctance Motor (SRM). TSF values depend on commutation angles during turn on, turn off, and overlapping angles. The proposed TSF and flower pollination algorithm evaluates the performance parameters using the machine model and controls the torque ripples for a wide range of speeds. Additionally, optimal results are obtained using three TSFs functions with valuable guidance provided for TSF selection. The proposed TSF with flower pollination algorithm-based intelligent controller finds its suitability for online evaluation of optimal turn on, turn off, and overlapping angles. The performance of the proposed method has effectively reduced the torque ripple in SRM than the Differential Evolution (DE) algorithm. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main aim of this paper is to present a novel control approach of an induction machine (IM) using an improved space vector modulation based direct torque control (SVM-DTC) on the basis of imaginary swapping instant technique. The improved control strategy is presented to surmount the drawbacks of the classical direct torque control (DTC) and to enhance the dynamic performance of the induction motor. This method requires neither angle identification nor sector determination; the imaginary swapping instant vector is used to fix the effective period in which the power is transferred to the IM. Both the classical DTC method and the suggested adaptive DTC techniques have been carried out in MATLAB/SimulinkTM. Simulation results shows the effectiveness of the enhanced control strategy and demonstrate that torque and flux ripples are massively diminished compared to the conventional DTC (CDTC) which gives a better performance. Finally, the system will also be tested for its robustness against variations in the IM parameters. [ABSTRACT FROM AUTHOR]

Direct Torque Control (DTC), a superior technique, which controls the stator flux and electromagnetic torque of an electrical machine. In spite of its numerous advantages, it possesses certain shortcomings like torque ripples, flux ripples, variable switching frequency and problems during the startup conditions. Recently, Matrix Converters (MC) have emerged as an efficient alternate for the Voltage Source Inverter employed in the DTC technique, which is capable of providing flexible and dynamic control over the torque and flux ripples associated in a machine. In this paper, a review on different control techniques associated in implementing the Matrix Converters for DTC method are categorized as follows: Subdivision of MC Voltage Vector method, SVM (Space Vector Modulation) based MC-DTC method, MC-DTC Duty Cycle Control, Employing Rotational Vectors of MC and Model Predictive Torque Control method. The pros and cons of each matrix converter fed direct torque control methods are presented by analyzing the experimental results from the literature. [ABSTRACT FROM AUTHOR]

The reduction in cogging torque enables smooth operation and an increase in the torque density of the machine. This research aims to minimize cogging torque in dual rotor single stator axial flux permanent magnet (AFPM) machine. Reduction in cogging torque makes the back EMF sinusoidal and reduces the torque ripples in AFPM machine. In this paper, an elliptical trapezoidal-shaped permanent magnet (PM) is proposed to minimize torque ripples of the AFPM machine. The 3D finite element analysis (FEA) is used for the analysis of AFPM machine. The optimization of AFPM machine is done by employing the asymmetric magnet-overhang along with the parameters of elliptical-shaped PM using Genetic algorithm (GA). [ABSTRACT FROM AUTHOR]

Torque smoothness is a strict requirement for synchronous reluctance motor (SynRM) industrial applications. The speed fluctuations induced by the high-frequency and low-frequency torque ripples deteriorate the drive performance. To suppress high-frequency torque ripples chronically omitted by conventional high-frequency signals injection methods at low-speed operation, this article proposes a bi-axes high-frequency signals injection (Bi-HFSI) scheme. A novel signal injection method is adopted, and the torque power spectrum can be broadened with discrete peaks effectively suppressed. In addition, aiming at decreasing low-frequency torque ripples, the Fourier iterative learning control algorithm that is effective in suppressing periodic disturbance is applied. It is combined with the Bi-HFSI scheme which mainly limits torque ripples at low frequencies including 1st, 2nd, and 6th harmonics. Theoretical analysis is presented, and the proposed method is verified by experiments on a 3-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

This article proposes an optimal scheme for an interior permanent-magnet synchronous motor (IPMSM) in electric vehicle drive system using novel model predictive torque control (MPTC) algorithm. A single optimal voltage space vector (VSV) is applied with a two-level voltage source inverter in the conventional MPTC. An improved MPTC is presented to reduce the drawbacks with satisfied torque reaction performance without adding the sampling time. First, set switching table to alleviate the calculated complexity which decreasing the selection of the appropriate VSVs. Second, optimize the duty cycle to restrain the torque ripple. Finally, the conventional MPTC and the proposed MPTC are compared in the aspects of torque and flux ripples, current harmonics, and computational level in the experiment using dSPACE. [ABSTRACT FROM AUTHOR]

In recent decades, switched reluctance motors (SRMs) have been attracting increasing attention as a promising type of traction motors for electric vehicle propulsion, owing to their robust construction, elimination of permanent magnets. However, their phase inductance profile contains significant high-order harmonics, which generates input-current and torque ripples under SRM drive with the conventional square phase-current waveform. This study solves this problem by proposing a novel phase-current waveform in replacement of this square waveform. The proposed waveform is a predetermined waveform that can be stored as a look-up table in the inverter controller and can be magnified or attenuated to adjust the output torque, similarly as the conventional square waveform. Certainly, SRMs generally exhibit magnetic non-linearity due to magnetic saturation, which complicates the analysis. Therefore, the proposed waveform is analytically derived under the assumption that the magnetisation of the motor remains below the saturation level because vehicle propulsion tends to require a torque output far smaller than the maximum rating of the motor in normal vehicle travel. The proposed phase-current waveform is experimentally tested in comparison with the conventional square phase-current waveform. Consequently, the proposed waveform revealed smaller ripples in both the input-current and torque, supporting the effectiveness of the proposed phase-current waveform. [ABSTRACT FROM AUTHOR]

This article proposes a fault-tolerant field-oriented control strategy for five-phase surface-mounted permanent magnet synchronous machine with non-sinusoidal back electromotive force under double-phase open-circuit fault, where the failure phases are either adjacent or nonadjacent. Based on the decoupled mathematical model after failure, the optimum current references which satisfy the zero-torque-pulsation constraint at the synchronous frame are presented. However, the torque operation range is small. So a full-range minimum torque ripples post-fault strategy is proposed. This strategy extends the torque operation range by gradually relaxing the zero-torque-pulsation constraint. And it can minimize the torque ripples for each torque reference value in the whole torque operation range. The synchronous frame proportional integral resonant controllers and carrier-based pulsewidth modulation are employed to implement the proposed post-fault strategy. The experimental results are provided to verify that the proposed strategy can achieve wider torque operation range and smaller torque ripples compared with the conventional fault-tolerant strategies. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hall sensors provide significant commutation signals for brushless DC (BLDC) motors. However, installation errors of Hall sensors are almost inevitable for BLDC motors, which can lead to commutation errors, further current ripples and torque ripples. Meanwhile, abnormal diode conducting in inactive phase can be aroused by large commutation errors at high speed. Therefore, the commutation errors make a negative influence on motor efficiency and degrade the performance of BLDC motors. Here, a simple and fast method to estimate the commutation error is proposed. Based on the analysis of the commutation process under commutation error, only the turn‐off phase current at the commutation instant is required for the estimation of delayed commutation error, while only the time interval of the turn‐off phase current decreasing to zero after commutation instant is needed when advanced commutation occurs. In order not to affect the dynamic performance of a BLDC motor, this study utilises a straightforward compensating method of commutation error. The experimental results represent that the proposed method is effective at different speeds, load torques, and under load‐variation with good transient performance. [ABSTRACT FROM AUTHOR]

Smart, Micro and Nano-grids are the future of electric power systems. In parallel with this future, electric vehicles (EVs) take a great deal of attention, as they are one of the important elements in these systems. Also, with the passage of time, the development continues in the technology of manufacturing EVs. Since the electric motor is the main component in these vehicles, research and development is continuing to find the most suitable motors that can work in such vehicles. The synchronous reluctance motor (SynRM) is the newest motor used in this industry. SynRMs faces different challenges, one of which is the torque ripples. Different trials were used to reduce or eliminate or minimize these ripples. Most of previous work focuses on the SynRM design parameters to reduce torque ripples. In this paper, the control methodology and the strong action controller (SAC) are used as a tool to reduce these ripples. The simulation results showed the effectiveness of the application of the proposed SAC in ripples factor reduction. This reduction represents a new contribution over the already existed techniques. [ABSTRACT FROM AUTHOR]

The unbalance between parameters of multiphase induction motors is mainly resulted from the variation in the first-phase resistance of stator and rotor. This paper aims to examine the performance of five-phase induction machine with unbalanced parameters. First, a model was set up for the five-phase induction machine, which can efficiently identify the defects in natural frame of the machine. Then, five-phase induction machine were simulated in difference scenarios on Matlab/Simulink. The variations in stator and rotor resistance were measured, and their impacts on several performance indices were analyzed in details. The results show that the variations directly affect the torque ripples, Joule losses, and mechanical speed of the fivephase induction machine. The research findings indicate the possibility to eliminate this effect through fault-tolerant control. [ABSTRACT FROM AUTHOR]

Five-phase permanent magnet synchronous motors offer merits of high fault tolerant capability and high torque per rms ampere and, thus, are suitable for applications, such as aerospace and electric vehicles. However, the complex machine model causes difficulties in controller design. Besides, having 32 voltage vectors with various effects on currents and torque, the selection of the optimal switching state becomes a challenge to achieve a performance tradeoff. This paper proposes an improved model predictive direct torque control (MPDTC) strategy consisting of a quadratic evaluation method (QEM) and a harmonic voltage elimination method (HVEM). In QEM, the preliminary vector is first chosen from the vectors of the outer decagon according to a cost function for torque and flux regulation. This preliminary vector, composed of three sets of different amplitudes, is further synthesized according to the error between the actual torque/flux and the references. In this way, the optimal voltage vector can be obtained without significantly increasing the computational burden. In HVEM, by subtracting the harmonics voltage component from the vector determined previously in QEM, the final voltage vector is obtained for mitigating stator harmonic currents. The proposed control strategy is compared with the conventional MPDTC approach. The results confirm the effectiveness of the proposed methods with good steady-state performance while maintaining quick dynamic responses. [ABSTRACT FROM AUTHOR]

Abstract It is well-known that switched reluctance motor, as a non-linear load, is a source of current ripples which reduces the life time of proton exchange membrane fuel cells and significantly affects their performances. In this work, optimal operations of autonomous stacked proton membrane fuel cells serving a switched reluctance motor are anticipated. Overall model comprising proton exchange membrane fuel cells stack and switched reluctance motor along with necessary interface and control elements are implemented using MATLAB/SIMULINK. Three key objectives are adopted to be optimized either individually or simultaneously such as: i) proton exchange membrane fuel cells stack efficiency, ii) torque per ampere ratio, and iii) torque smoothness factor. Six decision controlling parameters e.g. fuel cells' temperature, air flow rate, air pressure, fuel pressure, and turn on/off angles of switched reluctance motor represent the search space of dragonfly algorithm. Numerical results indicate that the proposed dragonfly algorithm-based method is capable of increasing proton exchange membrane fuel cells stack energy saving, and reducing of hydrogen consumption, ripples in switched reluctance motor torque and current of proton exchange membrane fuel cells stack. Finally, results generated by the dragonfly algorithm are appraised compared to those obtained by genetic algorithm which signifies its value. Highlights • Three objectives are targeted to improve the overall hybrid system performance. • Dragonfly algorithm gives the optimal settings of the six adapted control variables. • Various operating scenarios are demonstrated for the proposed methodology. • The results indicate that ripples and fuel consumptions can be enhanced. • Comparisons to others are made to signify the proposed method. [ABSTRACT FROM AUTHOR]

Cogging torque in flux‐switching permanent magnet (FSPM) machines dominates the whole torque ripples due to its special doubly salient structure and high air‐gap PM flux density. In this study, the chamfering method of right angles is utilised in both stator and rotor sides of FSPM machines to suppress the cogging torque. First, an analytical expression of cogging torque, taking the influence of the introduced right angles into consideration, is derived. On the basis of the derived model, the optimal dimensions of right angles are obtained and verified by both finite element analysis and experiments. Besides, the impacts of the proposed technique on phase electro‐motive force and electromagnetic torque are also evaluated. The predicted results indicate that the proposed technique can significantly reduce cogging torque in FSPM machines with negligible reduction of average torque. [ABSTRACT FROM AUTHOR]

With the increasing popularity of hybrid electric vehicles (HEVs), the demands of improving the fuel economy and energy efficiency of HEVs are enlarged. The technology electrical continuously variable transmission (E-CVT) system provides the opportunity to fulfill this requirement. However, conventional E-CVT with planetary gears suffer from frictional loss, high maintenance, and audible noise. Therefore, a series of gearless E-CVT propulsion systems are developed. Thereinto, a double-rotor single-stator brushless E-CVT having high torque density, reduced stator end winding length, and reduced copper loss was recently proposed. However, only torque of the E-CVT system is optimized by the genetic algorithm in the previous study. This paper adopts a differential evolution algorithm coupled with finite element method to optimize torque, energy efficiency, torque ripples, and multiobjective of the E-CVT system by reconfiguring the height of rotors, the areas of slots, and the height of yoke. It is simulated that by only tuning the weighting factors, the permanent magnetic machine in the E-CVT system can operate in the highest torque mode, highest energy efficiency mode, lowest torque ripples mode, and multiobjective optimization mode. [ABSTRACT FROM PUBLISHER]

Because of the current commutation and the double-salient pole structure of single-winding bearingless switched reluctance motors (SWBSRMs), the torque and radial forces have large ripples when present control methods are used. In order to solve those problems, a novel solution is proposed in this paper, which can achieve direct torque control (DTC) and direct force control (DFC) simultaneously. With the hysteresis-loop control of torque and flux linkage, the power switches of converter can be directly controlled based on the proposed space voltage vectors. First, the basic space voltage vectors are transformed correspondingly to realize DTC for BSRMs. After that, considering the generation principle of levitation forces, the basic space voltage vectors are transformed into equivalent space voltage vectors to facilitate the implementation of DFC. As a result, the torque and levitation forces can be controlled at the same time only with the developed equivalent space voltage vectors. The complicated current control algorithm is not needed, which is necessary for conventional methods. Moreover, the levitation performance is improved with the proposed method. Experimental results show that the torque ripple and radial displacements of SWBSRMs can be reduced approximately by 80% and 29%, respectively. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous motors (PMSMs) are exceptionally promising thanks to their many advantages compared with other types of electrical machines. Indeed, PMSMs are characterized by their important torque density, light weight, high air gap flux density, high acceleration, high efficiency and strong power-to-weight ratio. A surface-mounted PMSM (SPMSM) is used in this work. The SPMSM is built using a 2D finite element method (FEM). Cogging torque, torque ripples and back-EMF are examined during the design process in order to obtain sinusoidal back-EMF and to minimise torque ripples which are one of the major problems with PMSMs. Two procedures are used to reduce the cogging torque of SPMSM: the effect of slot opening and the influence of skewing the stator laminations. Cogging torque factor tc and the torque ripples factor tr have been calculated to compare the two configurations (open slots and closed slots). Then, the configuration with closed slots is utilised with skewing the stator laminations for different angle 0°, 10° and 15°. [ABSTRACT FROM AUTHOR]

A robust field-weakening method for direct-torque-controlled (DTC) synchronous reluctance motors is presented in this paper. The proposed algorithm achieves smooth transition between the constant torque and field-weakening regions. Maximum torque per ampere is utilized below base speed, while both the current and voltage limits of the drive system are satisfied in the field-weakening region. The proposed method is robust to the variations in the machine dq -axis inductances. This ensures the system stability during field-weakening operation, especially along the maximum torque per flux trajectory. The proposed algorithm is incorporated into the duty ratio regulation-based DTC to achieve high-performance torque and flux control in the field-weakening region. Experimental results included in this paper confirm the veracity of the proposed method. [ABSTRACT FROM AUTHOR]

The conventional direct torque control (DTC) features control structure simplicity, fast dynamic response, and parameter robustness. Nevertheless, it suffers from the problems of variable switching frequency and large torque ripples. This paper presents a modified DTC algorithm for interior permanent magnet synchronous motor drives with fast torque dynamics and constant switching frequency. The aforementioned problems are alleviated by adding a PI torque regulator to autonomously alter the effective duty cycle of the applied voltage vector. As a result, a constant switching frequency and also reduced torque ripples are obtained while retaining the benefits of the classical DTC. In addition, the torque dynamic response is further improved by introducing a modified switching table during transient conditions. By incorporating the modified switching table, the torque dynamic response is superior to that of the classical DTC. Simulation and experiment results included confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a robust field weakening method for the direct torque controlled (DTC) synchronous reluctance motors (RSMs). The proposed method ensures a smooth and stable transition between the maximum torque per ampere and field weakening including the maximum torque per flux regions. In addition, it is also robust to the variation in the machine dq-axes inductances in the field weakening region. The proposed algorithm is amalgamated with a duty ratio regulation based DTC to achieve high performance torque and flux control in the field weakening region. The effectiveness of the RSM drive is verified by both simulations and experiments. [ABSTRACT FROM PUBLISHER]

The generated torque ripples from the BLDC motor is the main issue that affects the drive performance of the BLDC drive system. In this paper, a new switching technique to minimize the torque ripples due to current commutation is proposed. The presented scheme has been implemented using a commercial and low-cost mid-range PIC microcontroller to generate the modified pulse width modulation (PWM) control signals. An analysis of phase current during commutation time is carried out. Experimental results verify the effectiveness of proposed method. Results had shown a smoother output torque and current produced in comparison with that using conventional PWM control technique with an average of 50 % reduction in the generated torque ripples. [ABSTRACT FROM AUTHOR]

One of the main challenges in designing high-power drive systems is the quality of the developed torque. High-torque-ripple magnitudes result in serious vibration and acoustic noise problems that affect the lifetime of a drive train. Multiphase machines intrinsically offer the torque with higher quality and are also being promoted for their high fault tolerant capability when compared with their three-phase counterparts. During open-phase conditions, the induced nonfundamental sequence current components have a detrimental effect on the machine performance especially under open-loop control. Although optimal current control is usually employed to ensure certain optimization criterion, such as minimizing torque ripples, optimizing flux distribution, or minimizing copper loss, are met, it usually entails a sophisticated current controller. This paper studies the effect of a stator winding connection of a five-phase induction machine on the induced torque ripples. Two possible connections, namely, star and pentagon connections are compared under healthy as well as fault conditions with one-line open. The comparison is conducted using both finite-element simulation and experimental results using a 1.5-Hp five-phase prototype induction machine. The comparison shows that the pentagon connection reduces the machine-induced torque ripples and improves the overall machine performance under fault conditions. [ABSTRACT FROM PUBLISHER]

The sinusoidal-wave and square-wave driving modes have been commonly used in permanent-magnet synchronous motor (PMSM) drives for household refrigerator compressors. In general, the sinusoidal-wave drive performs better in some aspects such as torque ripples, a starting performance, and a flux-weakening capability than the square-wave drive. The square-wave drive, however, has the advantage of higher efficiency at low-output-power conditions because of its relatively lower switching loss than the sinusoidal-wave drive. To selectively utilize the benefits of both driving modes, a seamless transition control between the two driving modes is proposed in this paper. Considering that the overall control structure of the sensorless PMSM drive is quite different according to the driving mode, initialization strategies, necessary for a smooth transition, for the pulse-width modulator of the inverter, speed and current controller, and sensorless position/speed estimator are presented. With the proposed method, a dual-mode operation of the sensorless PMSM drive can be achieved without stopping the compressor. The dynamic performance of the proposed transition scheme is tested using simulations and verified by experiments. Experimental result shows that the efficiency of a refrigerator increases up to 2 [%] using the dual-mode operation in comparison with the sinusoidal-wave only drive. [ABSTRACT FROM AUTHOR]

In this paper, an improved finite control set-model predictive control (FCS-MPC) with an optimized weighting factor is presented. The main goal of this paper is reducing the torque ripples when the FCS-MPC is implemented by means of the two-level inverter. For this purpose, the weighting factor is calculated via an optimization method. The optimization is based on dividing the control interval into two parts: active time for applying the active voltage vectors and zero time for applying the zero voltage. With this technique, the torque ripple is calculated as a function of weighting factor and it is optimized. The method is validated by simulations and experiments, using two-level inverter, at two speed regions (nominal speed and low speed). The results are compared with conventional FCS-MPC. [ABSTRACT FROM AUTHOR]

This paper presents a fuzzy logic hysteresis comparator-based direct torque control (DTC) scheme of an induction motor (IM) under varying dynamic conditions. The fuzzy logic controller (FLC) is used to adjust the bandwidth of the torque hysteresis controller in order to reduce the torque and flux ripples and, hence, to improve motor dynamic response. The effects of torque hysteresis bandwidth on the amplitude of torque ripples of an IM are also discussed in this paper. Based on the slopes of motor-estimated torque and stator current, an FLC is designed to select the optimum bandwidth of the torque hysteresis controller. This paper also proposes a simpler algorithm than the conventional trigonometric function-based algorithm to evaluate the sector number (required for DTC scheme) of the stator flux-linkage space vector. The proposed algorithm reduces the computational burden on the microprocessor. In order to test the performance of the proposed FLC-based DTC scheme for IM drive, a complete simulation model is developed using MATLAB/Simulink. The proposed FLC-based DTC scheme is also implemented in real time using DSP board DS1104 for a prototype 1/3 hp motor. The performance of the proposed drive is tested in both simulation and experiment. [ABSTRACT FROM AUTHOR]

Permanent-magnet step motors offer several advantages such as high efficiency, high power density, high torque-to-inertia ratio, and excellent durability and serviceability, as well as the absence of external rotor excitation and windings. The nonuniformity in the developed torque due to the nonsinusoidal flux distribution in the airgap is, however, the major obstacle in achieving global high-precision position tracking. When the position reference profile is a periodic signal of known period, such an obstacle may be however overcome by using recent learning control techniques, which require neither high gains in the inner speed/position control loops nor resetting procedures. An experimental comparison of two different recently designed learning position controls (“adaptive” and “iterative”) is, for the first time, carried out with reference to the same low-speed robotic application. Benefits and drawbacks of the two learning approaches are analyzed in detail. [ABSTRACT FROM AUTHOR]

In this work, a sensorless hysteresis direct torque control (HDTC) algorithm for a permanent magnet synchronous motor is described. The algorithm uses the output of two hysteresis controllers used in the traditional HDTC to determine two adjacent switching vectors per one sample time. The algorithm also uses the magnitude of the torque error, magnitude of the flux error and stator flux position to select the switching time for the selected vectors. The selection of the switching time utilises table structure which reduces the complexity of calculation. The simulation results of this proposed algorithm show adequate dynamic torque performance and considerable torque ripples reduction as well as lower current ripples and reduced electromagnetic interference noise level, as compared with HDTC. [ABSTRACT FROM AUTHOR]

In traditional Z-source inverter (ZSI) fed induction motor drives, the Z-source capacitor voltage and the motor terminal voltage are controlled by the shoot-through duty ratio and the modulation index, respectively. Modified voltage space vector has been proposed to improve motor terminal voltage control with effective DC boost in the DC link. For the same shootthrough duty ratio, modified voltage space vector provides better voltage boost in the DC link with reduced harmonics in the load side than the traditional voltage space vector. This paper presents an integrated control technique to minimise the electromagnetic torque ripples in the rotor of the ZSI-fed induction motor drives using modified voltage space vector. To improve the stability of the overall drive system, the motor terminal voltage alone is sensed instead of sensing the Z-source capacitor voltage and motor terminal voltage independently. This provides a single-stage controller for motor drive systems. The proposed induction motor drive system provides a better ride-through capability during voltage sags, better line harmonic profile, and minimisation of the torque ripples in the rotor. The proposed control technique is simulated using MATLAB/Simulink software, and analysis and experimental results have been presented to validate them. [ABSTRACT FROM AUTHOR]

Abstract: Sinusoidal motor''s mathematical models are usually obtained using classical d–q transformation in the case of salient pole synchronous motors having sinusoidal field distribution. In this paper, a new inverse modelling for synchronous motors is presented. This modelling is derived from the properties of constant torque curves in the Concordia''s reference frame. It takes into account the non-sinusoidal field distribution; EMF, self and mutual inductances having non-sinusoidal variations with respect to the angular rotor position. Both copper losses and torque ripples are minimized by adapted currents waveforms calculated from this model. Experimental evaluation was carried out on a DSP-controlled PMSM drive platform. Test results obtained demonstrate the effectiveness of the proposed method in reducing torque ripple. [Copyright &y& Elsevier]

This paper proposes a new passive filter topology to reduce torque ripples and harmonic noises in interior permanent magnet synchronous motor (IPMSM) derived by hysteresis direct control. The filter topology consists of compound dissipative filter cascaded by RLC low pass filter. The compound filter has two tuning frequency setting points, one at inverter switching frequency and the other at some average selected frequency. The filter topology is characterized by affecting inverter switching frequency in a way that decreases stress on switching elements including dv/dt. The filter topology uses series dissipative elements to reshape motor voltage waveform to provide semi-sinusoidal voltage to the motor windings. The simulation results show that the proposed topology effectively reduces torque ripples as well as total harmonic distortion (THD) and electro-magnetic interference (EMI) noise level. [ABSTRACT FROM AUTHOR]

This paper describes an active filter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The filter topology consists of an active filter and two RLC filters, and is connected to the main power circuit through a 1:1 transformer. The active filter is characterized by detecting the harmonics in the motor phase voltages and injecting equivalent harmonic voltages to produce almost sinusoidal voltage waveform to the motor terminals. The active filter uses hysteresis voltage controller while the motor main circuit uses hysteresis direct torque control. The simulation results of this combined control structure show considerable torque ripple reduction in the steady state range and adequate dynamic torque performance as well as considerable harmonic voltage and EMI noise reduction. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of torque and velocity ripple elimination in AC permanent magnet (PM) motor control systems. The torque ripples caused by DC offsets that are present in the current sensors of the motor driver and the digital-to-analog converters of the motion controller are studied and formulated mathematically. These torque ripples eventually generate velocity ripples at the speed output and degrade the system performance. In this paper the torque ripples are modeled as a sinusoidal function with a frequency depending on the motor speed. The internal model principle (IMP) is then used to design a controller to eliminate the torque and velocity ripples without estimating the amplitude and the phase values of the sinusoidal disturbance. A gain scheduled (GS) robust two degree of freedom (2DOF) speed regulator based on the IMP and the pole-zero placement is developed to eliminate the torque and velocity ripples and achieve a desirable tracking response. Simulation and experimental results reveal that the proposed GS robust 2DOF speed regulator can effectively eliminate the torque ripples generated by DC current offsets, and produce a velocity ripple-free output response. [ABSTRACT FROM PUBLISHER]

The high current ripple and torque ripple are the main drawbacks of the switched reluctance motor (SRM) since the nonlinearity and double saliency, which limits its applications. In order to eliminate the current variation and torque ripple, an optimized pulse width modulation (PWM) control is presented in this paper. The voltage ratio duty is able to be predicted precisely according to the information of the motor running parameter. Based on torque sharing functions (TSFs), the current profile is pre-computed and four regions are defined according to the reference current profiles. The three modes, excitation, demagnetization and freewheeling, are flexibly chosen according to the characteristic of the current profile. It is indicated that it is better than that of conventional PWM modulation in terms of current ripple and the current tracing performance is improved without increasing the switching frequency or changing the hysteresis band. The current ripple is defined as the peak-to-peak value dividing the average value and it is reduced by 40%. A comparison in terms of the torque ripple and copper loss is also carried out: the torque ripple is significantly reduced via the proposed scheme under both magnetic linear and saturation conditions. The torque ripple and copper loss are reduced by about 70% and 12%, respectively. The validity and effectiveness of the proposed control strategy is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]