Torque Ripple In Induction Motor Research Articles

Prior Computation of the Stator Current Dynamic Response for Torque Ripple Reduction in AC Motor Drives

In electric vehicles, the performance of the electric motor drive system depends on the characteristics of the control scheme applied. This paper discusses the torque ripple in an induction motor drive scheme exclusively and also proposes a new scheme to minimize it. The major cause of the torque ripple in induction motor drive is the presence of a high stator torque component (q-axis current) ripple. In the proposed scheme, the inverter is switched with the optimal duty ratio for the minimum q-axis current ripple. This leads to a decrease in q-axis current error and eventually torque ripple reduction. The distortion of the stator current waveform is also limited and gives rise to lower total harmonic distortion (THD). The feasibility of this proposed duty ratio modulated (DRM) improved torque and flux control scheme is studied using the MATLAB/Simulink computation tool and validated through appropriate experimentation.

Analysis of suitable converter for the implementation of drive system in solar photovoltaic panels

Introduction. Photovoltaic (PV) systems gained immense attraction in the recent years since it produces electricity without causing environmental pollution through direct conversion of solar irradiance into electricity. Solar PV panels produce DC power. The magnitude of this DC power varies with temperature and irradiance of the sun rays. The DC supply from solar panels can be regulated using DC-DC converter and then can further be converted into the desired AC voltage by means of a voltage source inverter before being fed to an induction motor (IM). The speed and torque of an IM, fed from PV arrays, can vary due to the variation in the output power of the panels. Goal of this work is to improve the dynamic performance and reduce the torque ripple of Cuk converter-inverter fed IM drive system. The novelty of the current work proposes interleaved Cuk converter between solar PV DC source and the inverter. Purpose. To provide continuous current using an interleaved Cuk converter to the IM drive and in turn to reduce the torque ripple in IM. Methodology. Introduced an interleaved Cuk converter which is a blend of Cuk converters connected in parallel with each other between solar PV arrays and IM drive system. Originality. Simulation results are obtained for Cuk converter and interleaved Cuk converter fed IM drive by means of MATLAB. The hardware setup for the same IM systems is developed. Practical value. Simulation and hardware results are coincided with each other and it is subject from the simulation and hardware results that the interleaved Cuk converter-inverter fed IM system produced results superior than the Cuk converter inverter fed IM drive system.

Analysis and Approximation of THD and Torque Ripple of Induction Motor for SVPWM Control of VSI

This article presents a harmonic analysis of the stator currents of a squirrel-cage induction motor fed by a voltage source inverter with PWM space vector control (SVPWM). The influence of PWM switching frequency and dead time (dead band) of controlled transistors on THD and electromagnetic torque ripple is shown. The aim is to determine the lowest switching frequency of the transistors for which the drive will operate correctly. Characteristics were determined as functions in the form of THD (fPWM), where the least square approximation was used for stator current measurements when the PWM switching frequency was changed. The approximations were realized for simulation and experimental results. To clarify the results, the operation of hardware PWM circuits in microcontrollers is analyzed.

A Variable Switching Frequency Space Vector Pulse Width Modulation Control Strategy of Induction Motor Drive System With Torque Ripple Prediction

The constant switching frequency space vector pulse width modulation (CSFSVPWM) generates high-frequency harmonics with integer multiples of the switching frequency, making it fail to fully exploit the potential of pulse width modulation (PWM) technique. In this paper, a variable switching frequency space vector pulse width modulation technique with the function of torque ripple prediction is proposed for induction motor drive system, which could optimize the high-frequency harmonic current distribution and torque ripple. The mathematical correlation between inverter average voltage and instantaneous voltage under the space vector pulse width modulation (SVPWM) is first analyzed, followed by the analysis of current ripple in a switching cycle using the typical seven-segment SVPWM, thus the torque ripple of induction motor during this period can be predicted. The switching period is dynamically adjusted according to the magnitude of predicted torque ripple, and the average switching frequency is maintained to be the same with that of CSFSVPWM. The effectiveness of the proposed method in suppressing high-frequency current harmonics and torque ripple is fully verified by experimenting on a 2.2 kW induction motor drive system, and a comprehensive comparison with CSFSVPWM and random PWM modulation is implemented.

Minimization of Torque Ripple in Induction Motor Drive by Optimal Harmonic Elimination

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Towards the optimal ‘slot combination’ for steady-state torque ripple minimization: an eight-pole cage rotor induction motor case study

This paper analyses the impact of the number of stator slots to rotor bars, i.e. the slot combination, in a cage rotor induction motor (IM) on its electromagnetic torque ripple during steady-state conditions. The study is focused on a conventional low voltage, eight-pole, three-phase, mains-fed IM design. To adequately evaluate the torque ripple magnitude, a ‘torque ripple factor’ is introduced and numerically calculated. To this end, IM behaviour in two common eight-pole stator slot number geometries is examined using numerical models, where, for each examined stator geometry, operation with a range of different rotor bar numbers used in practical IM designs is evaluated. For the sake of completeness and cross-validation, two different modelling approaches are used: a recently reported low-computational intensity winding function-based model and a commercial finite element analysis electromagnetic modelling software package. The paper findings deliver a detailed insight into the impact of rotor bar number, whether skewed or otherwise, on the motor steady-state torque ripple level. The presented results are indicative of the fact that the number of rotor bars only, and not the slot combination, is the dominant factor that influences the electromagnetic torque ripple in IMs with skewed rotor bars.

An Improved DTFC based Five Levels - NPC Inverter Fed Induction Motor for Torque Ripple Minimization

This paper presents a five level Neutral Point Clamped (NPC) inverter fed IM (Induction Motor) drive for variable speed application. In general the stator current is very highly affected by the harmonic components. It can be affecting the torque to produce high torque ripple in IM at maximum to low speed region. Since the drive performances are depends on mathematical model contains the parameters variations, noise, common mode voltage, flux variation and harmonic levels of the machine. Torque ripples and voltage saturations are the most significant problems in drive application. To overcome this problem the DTFC (direct torque and flux control) technique based five-level neutral-point-clamped (NPC-5L) approach is used. The proposed control scheme uses to stator current error as variable. Through the resistance estimated PI controller rules based the selection of voltage space vector modulation technique is optimized and motor performance level has been improved. The torque & speed are successfully controlled with less torque response. The results are compared and verified with conventional three phases VSI under different control technique by Matlab/Simulink.

Reduction of torque ripple in induction motor by artificial neural multinetworks

Reduction of torque ripple in induction motor by artificial neural multinetworks

A Tactical Chaos based PWM Technique for Distortion Restraint and Power Spectrum Shaping in Induction Motor Drives

The pulse width modulated voltage source inverters (PWM-VSI) dominate in the modern industrial environment. The conventional PWM methods are designed to have higher fundamental voltage, easy filtering and reduced total harmonic distortion (THD). There are number of clustered harmonics around the multiples of switching frequency in the output of conventional sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) inverters. This is due to their fixed switching frequency while the variable switching frequency makes the filtering very complex. Random carrier PWM (RCPWM) methods are the host of PWM methods, which use randomized carrier frequency and result in a harmonic profile with well distributed harmonic power (no harmonic possesses significant magnitude and hence no filtering is required). This paper proposes a chaos-based PWM (CPWM) strategy, which utilizes a chaotically changing switching frequency to spread the harmonics continuously to a wideband and to reduce the peak harmonics to a great extent. This can be an effective way to suppress the current harmonics and torque ripple in induction motor drives. The proposed CPWM scheme is simulated using MATLAB / SIMULINK software and implemented in three phase voltage source inverter (VSI) using field programmable gate array (FPGA).

Space-vector-based hybrid PWM technique to reduce peak-to-peak torque ripple in induction motor drives

Constant-volts-per-hertz induction motor drives and vector-controlled induction motor drives utilize pulsewidth modulation (PWM) to control the voltage applied on the motor. The method of PWM influences the pulsations in the torque developed by the motor. A space-vector-based approach to PWM facilitates special switching sequences involving the division of active state time. This paper proposes a space-vector-based hybrid PWM technique, which is a combination of the conventional and special switching sequences. The proposed hybrid PWM technique results in a lower peak-to-peak torque ripple than conventional space vector PWM (CSVPWM) at high speeds of an induction motor drive. Furthermore, the magnitude of the dominant torque harmonic due to the proposed hybrid PWM is significantly lower than that due to CSVPWM at high speeds of the drive. Experimental results from a 3.75-kW sensorless vector-controlled induction motor drive under various load conditions are presented to support analytical and simulation results.

DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI) in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC) voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

Three-Level Converters Back-to-Back DC Bus Control for Torque Ripple Reduction of Induction Motor

This paper proposes a regulation method of back-to- back connected three-level converters in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of three-level PWM rectifier. In the second part, three-level NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

Intelligent Control for Torque Ripple Minimization in Combined Vector and Direct Controls for High Performance of IM Drive

In Conventional Combined Vector and Direct Controls (VC-DTC) of induction motor, stator current is very rich in harmonic components. It leads to high torque ripple of induction motor in high and low speed region. To solve this problem, a control method based on the concept of fuzzy logic approach is used. The control scheme proposed uses stator current error as variable. Through the fuzzy logic controller rules, the choice of voltage space vector is optimized and then torque and speed are controlled successfully with a less ripple level in torque response, which improve the system's performance. Simulation results trough MATLAB/SIMULINK® software gave results that justify the claims.

Reduce Torque Ripple of IM by Approach Method DTC

This paper presents a new methodology for direct torque control (DTC) with improvement method control for induction motor (IM) systems. The application of approached method DTC (AMDTC), allows by using two hysteresis controllers to regulate torque and flux with the information of the angular location to address the switching table. The principal advantage of this AMDTC (optimization method of DTC) enables the minimization of the electromagnetic torque ripple and the reduction of the output current total harmonic distortion (THDI). Furthermore, it improved consumption quality of IM and it improved the lifespan of the motor. The switching characteristics of an inverter feeding an IM controlled with the AMDTC system are assessed in steady state.The proposed method of AMDTC is illustrated by computer simulations

Reduction of Torque Ripple in Induction Motor Drives Using an Advanced Hybrid PWM Technique

A voltage source inverter-fed induction motor produces a pulsating torque due to application of nonsinusoidal voltages. Torque pulsation is strongly influenced by the pulsewidth modulation (PWM) method employed. Conventional space vector PWM (CSVPWM) is known to result in less torque ripple than sine-triangle PWM. This paper aims at further reduction in the pulsating torque by employing advanced bus-clamping switching sequences, which apply an active vector twice in a subcycle. This paper proposes a hybrid PWM technique which employs such advanced bus-clamping sequences in conjunction with a conventional switching sequence. The proposed hybrid PWM technique is shown to reduce the torque ripple considerably over CSVPWM along with a marginal reduction in current ripple.