Torque Vibration Research Articles

DVR and D-STATCOM Mitigation Techniques of Power Quality Effects on Induction Motors

Power quality disturbances have always been a major concern among engineers. Any slight variation in voltage amplitude or frequency can cause customer equipment to fail, at a substantial cost in time and money.In this project we will use some mitigation techniques to protect the induction motor from excessive temperature (additional losses and high currents) and the rotor vibration torque pulsation caused by power quality disturbances.These mitigation techniques reduce the effects of the power quality disturbances on the induction motor, where the simulations done using MATLAB/SIMULINK.

Sensorless Control of Nonsinusoidal Permanent Magnet Brushless Motor Using Selective Torque Harmonic Elimination Control Method Based on Full-Order Sliding Mode Observer

Nowadays, due to excellent advantages of permanent magnet brushless (PMBL) motors such as high efficiency and high torque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL motor has neither ideal sinusoidal nor ideal trapezoidal back-EMF voltages, it is named nonideal (or nonsinusoidal) PMBL motor. Employing conventional control strategies of PMSMs and BLDCMs lowers the efficiency and leads to unwanted torque ripple, vibration, and acoustic noises. Moreover, in many applications to reduce the cost and enhance the reliability of drive, sensorless control techniques are used. This paper proposes a novel sensorless control for a nonsinusoidal PMBL motor with minimum torque ripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor position and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of motor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF voltage and able to run the motor from standstill with closed-loop control scheme. The capabilities of torque ripple minimization and sensorless strategies are demonstrated with some simulations.

Study on the characteristics of the torque vibration and the detection of the gap

Bobbin tool friction stir welding (BTFSW) is a new solid-state welding technology that has been developed successfully in many joining applications, such as thick plate and hollow component welding. The existence of the gap can possibly cause an unstable welding, and the variety of the torque is closely related to the existence of the gap. Compared with the conventional friction stir welding (FSW), BTFSW has the different tool and welding process, especially some new feature of the periodic vibration signal arises when welding two sheets in the presence of gaps. Compared with vibration-accelerated signal, torque signal is capable of reflecting the vibration of the welding process. The aim of this study was to develop an effective algorithm to detect gaps in BTFSW operations. Experimental studies were conducted to determine the features of welding process parameters and the gap. Time-frequency (TF) analysis provides a display of subtle torque features, shows the corresponding duration of low frequency signal clearly. Followed by a low-pass filter, gauss wavelet transform (WT) algorithm would improve the detection and identification of the gap presence. Several experimental studies with a variety of process parameters and proposed algorithm was shown to be able to reliably detect the presence of gaps in BTFSW operations for traverse speeds below 200 mm/min and gap sizes above 0.3 mm. This gauss WT algorithm could become a useful noninvasive tool for welding quality assessment in practice.

Autobalancing Control for MSCMG Based on Sliding-Mode Observer and Adaptive Compensation

This study proposes an autobalancing control method for the magnetically suspended control moment gyro (MSCMG) to achieve clean vibration force and torque properties. The rotor imbalance of the MSCMG generates centrifugal force and moment, which degrade the performance of the MSCMG. Since the voltage-type power amplifiers are used onboard and the dc voltage on the spacecraft is limited, the characteristics of the current loop must be taken into consideration. Moreover, the active magnetic bearing deviates from its equilibrium point when the rotor attempts to rotate around its principle axis of inertia, which leads to errors for the traditional linearized electromagnetic force model. To reject the influence of magnetic force parameter perturbation, a sliding-mode observer is designed to obtain the rotor imbalance owing to its robustness about the model error. Then, an adaptive compensation algorithm is designed to produce the target coil current to compensate the displacement stiffness force, leading to a clean vibration electromagnetic force output. It can automatically compensate the variations of the power amplifier and the induced electromotive force, and perfect imbalance vibration suppression is achieved for both vibration force and vibration torque. The simulation and experiment results demonstrate the effectiveness and superiority of the proposed method.

A Two Fiber Bragg Gratings Sensing System to Monitor the Torque of Rotating Shaft.

By fixing two FBGs on the surface of a rotating shaft along the direction of ±45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, the dependence relation of the dynamic difference of central wavelengths on the torque and torsion angle of the rotating shaft has been deduced. To verify an optical fiber sensing system, a series of sensing experiments have been completed and the measured data are approximately consistent with the theoretical analysis. The difference of two central wavelengths can be expressed as the sum of two parts: a “DC” part and a harmonic “AC” part. The driving torque or torsion angle is linear with the “DC” part of the difference of two central wavelengths, the harmonic “AC” part, meaning the torsion angle vibration, illustrates that periodic vibration torque may be caused by inhomogeneous centrifugal forces or inhomogeneous additional torques produced by the driving system and the load.

Analysis of starting resistance moment of direct drive wind turbine

Permanent magnet motor in the process of running, the permanent magnets provided the magnetic field , the core will have a strong attraction, produce the cogging torque and torque ripple, vibration and noise and other disharmony factors, seriously affect the control precision of the motor system.Therefore, in the design of permanent magnet wind turbine generator, weaken the cogging torque is very important.

Comparative Study of Predictive and Resonant Controllers in Fault-Tolerant Five-Phase Induction Motor Drives

One of the most attractive features of multiphase machines is the fault-tolerant capability due to the higher number of phases. Different postfault control strategies based on hysteresis, proportional integral (PI)-resonant, and predictive techniques have been recently proposed. They all proved their capabilities to withstand fault situations and to preserve the fundamental component of the air-gap field, while achieving minimum losses, maximum torque per ampere, and reducing torque vibrations. Nonetheless, due to their recent introduction, no thorough study has yet appeared comparing the performance of these controllers. In this paper, two open-phase fault-tolerant control schemes are experimentally compared in a real five-phase induction machine. The controllers being compared are based on PI-resonant and predictive control techniques, respectively. The experiments include pre- and postfault situations. Obtained results show that both control methods offer nearly the same performance. When compared, predictive control provides faster control response and superior performance at low-speed operation but is found to be less resilient to fault detection delays and to have higher current ripple. Regarding the controller implementation, it is shown that the transition from prefault to postfault operation involves modeling the nonlinear effects observed when an open-phase fault occurs for the predictive controller and proper retuning of the PI trackers for the PI-resonant controller, to ensure postfault operation.

オープンループ制御による永久磁石同期電動機の方形波電圧駆動

This paper proposes a permanent magnet synchronous motor (PMSM) control strategy based on open-loop control. Low-frequency torque vibration excluding the sixth- or twelfth-order harmonics occurs because the voltage fluctuates from the transition to the square-wave voltage. Therefore, the proposed control uses a variable band-pass filter to reduce low-frequency torque vibration. In the experimental results, the low-frequency q-axis current decreased by approximately 50%.

On the Averaging in Strongly Damped Systems: The General Approach and its Application to Asymptotic Analysis of the Sommerfeld Effect

Passage through resonance of an unbalanced rotor mounted on a strongly damped oscillating system that is excited by an asynchronous motor of limited power is investigated using an averaging procedure for a partially strongly damped system. The approach is closely related to a singular perturbation technique. It is demonstrated that the system's dynamics can be reduced on the slow manifold to a single first-order differential equation predicting both the stationary and transient solutions of the original system. Furthermore, the technique provides insight into the system's dynamics, enabling an outline of two simple methods to avoid capture into resonance. The first method is based on an active compensation of the small averaged vibrational torque, and the second method is a passive mechanical device reducing vibration amplitudes. The approximate results obtained were compared with the direct numerical simulations of the full system and demonstrate very good accuracy everywhere except in the vicinity of the bifurcation point. In this vicinity, the asymptotically long time interval is not sufficient for predicting capture into resonance.

Thermodynamic and dynamic modeling of a single cylinder four stroke diesel engine

In this study the conjugate thermodynamic and dynamic modeling of a single cylinder four-stroke diesel engine was conducted. The gas pressure in cylinder was calculated with the first law of the thermodynamic and the general state equation of the perfect gases. The variation of the heat, given to the working fluid during the heating process of the thermodynamic cycle, was modeled with the Gaussian function. The dynamic model of the engine consists of the motion equations of piston, conrod and crankshaft. Conrod motion was modeled by 2 translational and 1 angular motion equations. In the derivation of the motion equations, the Newton method was used. Motion equations involve hydrodynamic and asperity frictions as well as gas forces. By preparing a heat release rate profile consistent with ones given in the literature, thermal efficiency, knocking, vibration, torque and emission characteristics of the engine were investigated. The counterweight mass and its radial distance were optimized. At full load, if the heat release period is initiated soon after the piston passed the top dead center, the pressure rise rate becomes critical from the knocking point of view however, a couple of degree of retarding of the heat release period avoids the knocking without causing significant loss in thermal efficiency. If the throttling is more than 70%, the temperature of the combustion gas is high enough for NOx formation. At full load the vibrational torque exerting on the crankshaft was determined as about 17 times the engine torque.

Impact of the Converter Control Strategies on the Drive Train of Wind Turbine during Voltage Dips

The impact of converter control strategies on the drive train of wind turbines during voltage dips is investigated in this paper using a full electromechanical model. Aerodynamics and tower vibration are taken into consideration by means of a simulation program, named FAST. Detailed gearbox and electrical subsystems are represented in MATLAB. The dynamic response of electromagnetic torque and its impact on the mechanical variables are the concern in this paper and the response of electrical variables is less discussed. From the mechanical aspects, the effect of rising power recovery speed and unsymmetrical voltage dips are analyzed on the basis of the dynamic response of the high-speed shaft (HSS). A comparison of the impact on the drive train is made for two converter control strategies during small voltage dips. Through the analysis of torque, speed and tower vibration, the results indicate that both power recovery speed and the sudden torque sag have a significant impact on drive trains, and the effects depend on the different control strategies. Moreover, resonance might be excited on the drive train by an unbalanced voltage.

Research on the torque transmissibility of the passive torsional vibration isolator in an automotive clutch damper

The input torque vibrations (i.e. the fluctuations or ripples) induced by internal-combustion engines is a significant source of noise, vibration and harshness issues, which cause problems in automotive powertrains. This is because the torque vibrations are primarily transmitted to the input shaft of automotive transmissions (e.g. automatic transmissions) when the lock-up clutch is closed. Hence, a passive torsional vibration isolator with helical springs is generally inserted between the engine and the transmission to isolate the input vibratory energy. Although a passive isolator is used to resolve the noise, vibration and harshness issues because it generally exhibits frequencies with a very low transmissibility, the primary performance of the isolator is evaluated using only the static torsional spring characteristics and the measurement of the angular velocity or the angular acceleration. In this study, a low-inertia dynamometer incorporating state-of-the-art torque-sensing technology was used to evaluate experimentally the torque transmissibility of a torsional vibration isolator as a primary dynamic performance index for the first time.

Open-Switch Fault Tolerance Control for a Three-Level NPC/T-Type Rectifier in Wind Turbine Systems

Three-level topologies are widely used in back-to-back converters of wind turbine generation (WTG) systems. In comparison with a conventional two-level topology, three-level topologies have more advantages, particularly for the high power. Neutral-point clamped (NPC) and T-type are typical three-level topologies. An open-switch fault of a three-level rectifier that is connected to a permanent-magnet synchronous generator (PMSG) leads to the current distortion and torque vibration in WTG systems. Furthermore, WTG systems can break down in the worst case. Therefore, a tolerance control for open-switch faults is required to improve the reliability of WTG systems. WTG systems by applying the tolerance control can be stopped safely and prevent additional problems. Depending on the situation, it can keep the operation of WTG systems under open-switch fault. The effects of outer open-switch faults of three-level rectifiers are analyzed by considering PMSG specifications in this paper. Moreover, a tolerance control for outer open-switch faults of the NPC and T-type three-level rectifiers are proposed with existing tolerance controls for inner open-switch faults. The proposed tolerance control is to inject the exact $d$-axis current value to eliminate current distortion. The simulation and experiment are conducted to prove the feasibility of the proposed tolerance control and to identify its performance.

Open-Switch Fault Detection Method of a Back-to-Back Converter Using NPC Topology for Wind Turbine Systems

In wind turbine generation (WTG) systems, a back-to-back converter with a neutral-point-clamped (NPC) topology is widely used because this topology has more advantages than a conventional two-level topology, particularly when operating at high power. There are 12 switches in the NPC topology. An open-switch fault in the NPC rectifier of the back-to-back converter leads to the distortion of the input current and torque vibration in the system. Additionally, an open-switch fault in the NPC inverter of the back-to-back converter causes the distortion of the output current. Furthermore, the WTG system can break down in the worst case scenario. To improve the reliability of WTG systems, an open-switch fault detection method for back-to-back converters using the NPC topology is required. This study analyzes effects of inner and outer open-switch faults of the NPC rectifier and inverter and describes a novel open-switch fault detection method for all possible open-switch faults in the back-to-back converter.

Acoustic Noise Reduction of BLDC Motor Drive Using One-Cycle Current Control Strategy

Torque ripple and resulted acoustic noise and vibration are the main disadvantages of brushless DC (BLDC) motor drives. In this study, One-Cycle Control (OCC) is developed for current regulation of brushless DC (BLDC) motor drive as a unified constant-frequency integration control strategy. Employing one-cycle control strategy reduces high frequency torque ripple of conventional hysteresis current controllers leading to lower acoustic noise and vibration in the drive. To enhance reliability and reducing drive cost, an improved rotor position estimation technique is implemented. OCC strategy and sensorless method are realized using a low-cost general-purpose AVR microcontroller (Atmega8). It is shown that torque ripple, acoustic noise and vibration are reduced via OCC method comparing to conventional hysteresis control strategy. Computer simulations and experimental results with a 375W, 16 poles BLDC motor, demonstrate improved behavior of developed sensorless BLDC drive operation.

Nonlinear Dynamic Analysis of Drill String System for Horizontal Oil Well with Different Positions of Stabilizers

For the horizontal well of petroleum drilling engineering, the horizontal section of drill string was selected as a research object. Collision and friction between drill string and well wall, displacement response on the drill bit and other boundary conditions were considered in this simulated modeling. By using finite element analysis software ANSYS, the dynamic characteristics of horizontal section of drill string were calculated and discussed. The effect of different positions of stabilizers on the vibration characteristics of drill string were studied specially. The calculated results show that the installation positions of stabilizers have remarkable effects on the dynamic characteristics of drill string. It will change the lateral vibration and whirling motion of drill string remarkably. Furthermore, the reasonably installation of the stabilizers can decrease the amplitudes of lateral vibration and transient torque. Those results may provide some guidance for the vibration analysis of drill string system.

Power transmission dynamics in micro and macro slip regions for a metal v-belt continuously variable transmission under external vibrations

In this paper, the power transmission dynamics of a metal v-belt continuously variable transmission (CVT) under external vibration conditions were investigated for the micro and macro slip regions. A CVT variator simulator was developed based on the CVT power transmission dynamics. Using the simulator, the influence of a slip on the external vibration transmission characteristics was analyzed in time and frequency domain. From the analysis results, it was found that the external vibration transmission characteristics were different between the micro slip region and the macro slip region. In the micro slip region, the vibrations of the primary and the secondary pulleys were coupled, which means that the vibration characteristics of the primary and secondary pulleys are determined by the torque vibrations characteristics of both the primary and secondary torque. However, in the macro slip region, the vibrations of the pulleys are decoupled and the vibration characteristic of each pulley is determined by the torque vibration of the corresponding side. Experiments were performed to validate the external vibration transmission characteristics for the load torque fluctuation. The test results were in good agreement with the simulation results. It is expected that the different vibration transmission characteristics of the micro and macro slip regions can be used to detect a macro slip in the CVT variator during actual operation.

Can passive stretch inhibit motoneuron facilitation in the human plantar flexors?

The purpose of the present study was to examine the possible inhibitory effect of passive plantar flexor muscle stretching on the motoneuron facilitatory system. Achilles tendon vibration (70 Hz) and triceps surae electrical stimulation (20 Hz) were imposed simultaneously in 11 subjects to elicit contraction through reflexive pathways in two experiments. In experiment 1, a vibration-stimulation protocol was implemented with the ankle joint plantar flexed (+10°), neutral (0°), and dorsiflexed (-10°). In experiment 2, the vibration-stimulation protocol was performed twice before (control), then immediately, 5, 10, and 15 min after a 5-min intermittent muscle stretch protocol. Plantar flexor torque and medial and lateral gastrocnemius and soleus (EMGSol) EMG amplitudes measured during and after (i.e., self-sustained motor unit firing) the vibration protocol were used as an indicator of this facilitatory pathway. In experiment 1, vibration torque, self-sustained torque and EMGSol were higher with the ankle at -10° compared with 0° and +10°, suggesting that this method is valid to assess motoneuronal facilitation. In experiment 2, torque during vibration was reduced by ∼ 60% immediately after stretch and remained depressed by ∼ 35% at 5 min after stretch (P < 0.05). Self-sustained torque was also reduced by ∼ 65% immediately after stretch (P < 0.05) but recovered by 5 min. Similarly, medial gastrocnemius EMG during vibration was reduced by ∼ 40% immediately after stretch (P < 0.05), and EMGSol during the self-sustained torque period was reduced by 44% immediately after stretch (P < 0.05). In conclusion, passive stretch negatively affected the motoneuronal amplification for at least 5 min, suggesting that motoneuron disfacilitation is a possible mechanism influencing the stretch-induced torque loss.

Control Techniques for Accessory Power Unit Employed in Hybrid Electric Vehicle to Reduce the Torque Pulsations and Vibrations

A multilevel inverter is a power electronic Accessory Power Unit (APU) built to synthesize a desired AC voltage from several levels of DC voltages. Hybrid Electric Vehicles (HEVs) work through a combination of an internal combustion engine, a bank of batteries, and an electric motor. In fact, the concept is so advantageous that several major drives manufacturers have obtained recent patents on APU and associated switching techniques. For this reason, the investigation of methods to increase the reliability of APU is of high interest. It is evident that the multilevel concept will be a prominent choice for power electronic systems in future years. This paper proposes a comparison between different switching strategies for APU, based on Sinusoidal Pulse Width Modulation (SPWM) and Space Vector Modulation (SVM). The work strives hard to present the scrutiny that has been made between different open loop Pulse Width Modulation (PWM) control techniques for multilevel based APU. The comparison is made in terms of Total Harmonic Distortion (THD), switching frequency, fundamental and harmonic RMS of the voltage and current. The quality of output waveforms eliminates the torque pulsations and hence the vibrations of the electrical drive, which is a critical parameter for the smoothness of HEVs.

Vibration Suppression Control Method using Extended State Observer for Angular Transmission Error in Cycloid Gear

This paper proposes a method for suppressing the speed vibration caused by the angular transmission error in cycloid gears used in industrial robots. It is important for industrial robots to have high accuracy. However, cycloid gears with an angular transmission error may cause vibration in the arms of a robot. The proposed method for compensating for the speed vibration uses a new extended state observer that is based on a model that considers a cycloid gear with an angular transmission error. A compensation current is generated by using the torque vibration which is converted from the estimated speed vibration. The speed vibration is suppressed using this compensation current. The experimental results show that the proposed system suppresses the vibration at the load speed.