Torque Vibration Research Articles

K-wire is more damaging than standard or acrylic drill bits when evaluating torsional properties of rabbit (Oryctolagus cuniculi) femurs.

The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire. 24 pairs of rabbit femora. After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated. The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types. Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit.

A novel auxetic stator winding to improve the performance of permanent magnet synchronous electric motors

High efficiency and torque density in permanent magnet synchronous motors (PMSMs) have contributed to their increasing popularity. Nonetheless, these advantages are compromised by higher vibration levels resulting from the torque ripple issue and magnetic flux density in the stator, causing magnetic forces on the stator surface. In this study, a new smart shape for the stator winding is proposed which reduces unwanted torque vibration and the overall magnetic flux density while keeping the same motor efficiency. The proposed windings shape is designed based on the auxetic principle and a locally resonant mechanism (LRM). Afterward, the proposed and original PMSM models are compared by looking at the average torque, total losses, torque ripple, flux density, output power, and motor efficiency under different speed operating conditions. In addition, the sensitivity analyses of the proposed model reveal the influence of auxetic structural parameters and initial mechanical angle on the system’s performance, which can be utilized to control the physical and mechanical properties of the system. According to the results, the designed model reduces torque ripple and magnetic flux density in the stator region by 41.38% and 4.70%, respectively, while the motor efficiency remains unaffected. The present work offers a potentially robust and affordable solution for regulating the vibration behavior of electric motors without impacting power efficiency.

Control Techniques of the Modified Stator and Rotor Pole Shape in a 6/4 Switched Reluctance Motor: Effects on Torque Ripple Minimization

A switched reluctance motor (SRM) provides the advantages of simple and robust motor structure. But in switched reluctance motors (SRMs), as the result of the double ridged structure of motor, the torque vibrations and acoustic noise are relatively higher as against the sinusoidal machines. This study intends to minimize the torque ripple of a SRM. In machine’s design, new control approaches were employed by modifying the stator and rotor pole shapes in order to minimize the torque ripple in SRM. Moreover, by observing the performance of 6/4 SRM under steady-state conditions and at constant dwell angles for fan load, torque ripple (TR) analyses were performed. The driver was simulated for current control (CC), and control of sum of squared phase currents (SPC). Fuzzy Logic Controller (FLC) was also applied on speed loop in order to minimize torque ripple, and to improve the effective torque. In MATLAB/SIMULINK environment, the results are being discussed in detail. The FLC technique provided successful results in improving the effective torque ripple of SRM. The results of simulation were verified by the experimental results.

Multi-Parameter Fuzzy-Based Neural Network Sensorless PMSM Iterative Learning Control Algorithm for Vibration Suppression of Ship Rim-Driven Thruster

Aiming to reduce motor speed estimation and torque vibration present in the permanent magnet synchronous motors (PMSMs) of rim-driven thrusters (RDTs), a position-sensorless control algorithm using an adaptive second-order sliding mode observer (SMO) based on the super-twisting algorithm (STA) is proposed. In which the sliding mode coefficients can be adaptively tuned. Similarly, an iterative learning control (ILC) algorithm is presented to enhance the robustness of the velocity adjustment loop. By continuously learning and adjusting the difference between the actual speed and given speed of RDT motor through ILC algorithm, online compensation for the q-axis given current of RDT motor is achieved, thereby suppressing periodic speed fluctuations during motor running. Fuzzy neural network (FNN) training can be used to optimize the STA-SMO and ILC parameters of RDT control system, while improving speed tracking accuracy. Finally, simulation and experimental verifications have been conducted on the vector control system based on the conventional PI-STA and modified ILC-STA. The results show that the modified algorithm can effectively suppress the estimated speed and torque ripple of RDT motor, which greatly improves the speed tracking accuracy.

Behavior analysis of dual-star permanent magnet synchronous generator with inter-turn short fault

ABSTRACT The dual-star PMSMs (DSPMSM) are widely used in high-power applications due to their robustness and reliability. As they mostly work in harsh environments, they are commonly subject to many faults. One of the most dangerous faults is the inter-turn short fault (ITSF), which induces torque vibrations and overheating inside the machine, and may lead to other faults. To properly handle this issue, it must be correctly understood, and the relationship between different machine’s quantities (speed, dq currents, fault ratio and resistance) and the severity of the fault (torque’s oscillations and short-circuit current) must be established. In this context, this paper presents a detailed analysis of the DSPMSM behavior under a single ITSF, considering the influence of the mentioned quantities and the PWM converter on torque oscillations and short-circuit current. A mathematical model of the machine is developed, and a hysteresis current controller is used to impose the desired direct and quadrature axis stator currents. Simulation tests are conducted by considering different scenarios. Simulation results showed that to reduce fault severity, a trade-off between speed reduction and flux weakening must be accomplished, consequently accepting some performance degradation. Also, results showed the complex behavior of the short-circuit current, as it does not rely linearly on fault parameters.

Controller Design and Shaft Torque Vibration Suppression for Servomechanism With Elasticity

Controller Design and Shaft Torque Vibration Suppression for Servomechanism With Elasticity

Reduction of Torque Vibration in Integrated On-board Chargers Using Stator Windings of an IPMSM

This study proposed a control method to reduce the torque ripple vibration of an integrated on-board charger using the windings of an interior permanent magnet synchronous motor (IPMSM). During a battery-charging operation, stopping the motor results in noise, as well as damage to the motor and other components from the torque vibration caused by the charging current. In the proposed control method, the generated torque was estimated using a back-electromotive force table, and the phase current was controlled to eliminate the torque. The proposed method can suppress torque vibration, irrespective of the angle of the rotor in the IPMSM. The effectiveness of the proposed method was verified experimentally, with the torque vibration suppressed by 94% compared with that of the conventional control method.

Frequency-Domain Analysis and Joint Torque Vibration Suppression Control on Two-Input-Two-Output Torque Difference Amplification Motor Drive System of Electrified Vehicles

<div>To improve the cornering performance, a torque vectoring differential (TVD) that generates a torque difference between the left and right wheels has been developed. Particularly, the use of multiple electric traction motors can easily achieve this. A TVD with a two-motor-torque difference amplification mechanism (TDA-TVD), which employs a unique alignment of planetary gears, has been studied and it can generate a larger torque difference compared to an individual-wheel-drive (IWD) system in the case of using the equal torque output from the traction motors. However, due to the mechanically complicated driving force transmission system including driveshafts and planetary gears, TDA-TVD is prone to cause torsional vibrations of the driveshaft, and the yaw rate of the vehicle body while differential torque is generated. A previous study derived a dynamic model TDA-TVD and designed a vibration suppression feedforward controller. While the study demonstrated a certain vibration suppression performance, it did not strictly consider the load side characteristics during the yaw motion. In addition, there was no frequency-domain analysis either. On the other hand, this study will analyze TDA-TVD in the frequency domain and propose a novel modeling method to construct vibration suppression controllers that deal with both longitudinal motion and yaw motion simultaneously. First, this article shows a theoretical frequency-domain analysis using matrices and obtains resonance frequencies of TDA-TVD. Second, TDA-TVD is modeled based on a summation-differential mode transformation (SDMT). Third, simulations and experimental evaluations of vibration suppression controls using a real vehicle equipped with the TDA-TVD are demonstrated.</div>

Simulation of Switched Reluctance Motor with an optimized Direct Torque Control minimizing Torque Ripple

Switched reluctance motor (SRM) is paid more attention in industrial usage because of its simple structure and low cost. But the inherent torque vibration situation and noise caused by vibration limited its application in electrified vehicles, which requests sooth torque output. To meet the demand of minimizing torque ripple, this article presents a new direct torque control (DTC) method with a changeable reference flux and a more steady switching table to lower the torque ripple and power consumption. This new method is carried out by MATLAB simulations which show that the new DTC method enhances the response of the focused 4-phase SRM to reach the given speed faster and meanwhile minimizing the torque ripple compared to the traditional DTC method.

Operation Analysis and Torque Performance Optimization of a Novel Self-Aligning Limited-Angle Vibration Torque Machine

Operation Analysis and Torque Performance Optimization of a Novel Self-Aligning Limited-Angle Vibration Torque Machine

Influence of misalignment of connection of electrical machine shafts on the nature of electric power of the induction motor

Purpose. To identify the vibration power components caused by misalignment of electrical machine shafts in the instantaneous power of the induction motor. Methodology. The power components of the induction motor are analytically determined taking into account the power caused by torque vibrations on the shaft. Based on this, using the methods of mathematical modelling in the visual programming environment, the known model of a three-phase induction motor with a short-circuited rotor has been made. In addition, elements and connections are introduced which realize the formation of the moment caused by the imbalance of rotating masses. Using Fourier transform of the electric power of the induction motor, we determine its discrete spectrum. Experimental research is conducted on the electric power of the induction motor with a short-circuited rotor, in similar model conditions, on laboratory equipment. With the use of a virtual device synthesized in the LabVIEW package, the wavelet analysis of stator electric power of the motor of laboratory electrotechnical complex is performed. Findings. Differential equations of the induction motor with a short-circuited rotor in abc coordinate system are obtained, which reflect the distribution of instantaneous power in the machine taking into account the vibration moment. As a result of modelling according to the specified equations of the induction machine, in the conditions of full symmetry of parameters of the scheme and the mode with eccentricity of rotating masses, low-frequency vibrations of electric power of a stator with frequency of 25 Hz have been found. Similar results were obtained as a result of wavelet analysis of the electric power of an induction motor of a laboratory electrotechnical complex. Originality. Rationality of use of instantaneous electrical power of induction motor stator for detection of vibration caused by misalignment between its shaft and the shaft of another machine has been substantiated, which allows detecting vibration without complex methods of measuring vibration displacement and its derivatives. Practical value. Detecting vibration by measuring the electrical parameters of the stator circuit of the induction motor and determining the vibrations of its instantaneous power without the use of specialized equipment significantly simplify the procedure of vibration diagnostics at its early stages.

Controlling Torque Ripple Vibration in a Single-Phase PFC Using the Neutral Point of an IPMSM

This paper proposes a method to reduce the torque ripple vibration of an integrated power factor correction (PFC) converter by using the zero-phase inductance of an interior permanent magnet synchronous motor (IPMSM) when the motor is not running. When an integrated PFC converter is applied to electric vehicle (EV) chargers, it is necessary to reduce the torque oscillation of the motor caused by the charging current. In an integrated PFC converter using an IPMSM, the zero-phase current and magnetomotive force harmonics of the permanent magnet cause torque vibration. In the proposed control method, the generated torque is estimated using the back EMF table, and the phase current is controlled to cancel it. The proposed method can be used to suppress torque vibration irrespective of the mechanical angle of the rotor. The effectiveness of the proposed method is experimentally verified. Using the proposed method, the torque vibration can be suppressed by up to 91.3% as compared to that in the case of the conventional control method. Furthermore, a power factor of 99.9% is achieved under a load condition of 1kW.

A Novel Attitude Angular Velocity Measurement Method Based on Mass Unbalance Vibration Suppression of Magnetic Bearing

In order to eliminate the influence of synchronous harmonic current caused by mass imbalance of magnetic bearing on attitude angular velocity measurement accuracy, a notch filter which can adjust the notch depth and center frequency is proposed. Firstly, the influence of synchronous harmonic current on the measurement accuracy of magnetically suspended control and sensitive gyroscope(MSCSG) is analyzed, and then a notch filter is designed which can adjust the notch depth and center frequency, and the measurement accuracy and stability of the system after eliminating synchronous harmonic current are analyzed. Simulation results show that the proposed method can effectively suppress the unbalance vibration torque and eliminate synchronous harmonic current. Finally, the correctness and effectiveness of the proposed method are verified by experiments. Experimental results show that the proposed method can reduce the vibration torque by 50% and improve the measurement accuracy of attitude angular velocity significantly.

Power Consumption Simulation of Servo Motors Focusing on the Influence of Mechanical Vibration on Motor Efficiency

This paper presents a simulation method for the power consumption of servo motors, focusing on the influence of vibrations on the motor efficiency. An apparatus consisting of two servo motors connected through a coupling was specifically designed for this study. The efficiency of the servo motor was experimentally investigated for several torque vibration levels imposed through the selection of the control parameters, and the torque vibration level was quantified through the standard deviation of the torque signal. The efficiency map characteristics for each torque oscillating level were determined. A numerical model of the apparatus clarifying the dependency of the coupling characteristics on the oscillating torque was developed, and the torque oscillation of the system was simulated. A model based on the measured motor efficiency maps and the torque oscillation level was developed to simulate the motor efficiency under several torque vibrating conditions. Finally, the power consumption of the motor was simulated based on the simulated efficiency and mechanical power. A balance of input, output, and loss powers was presented, and the experimental measurements were compared with the simulation results. The power consumption of the motor increased when the torque oscillated owing to vibrations, and the loss of power due to both oscillations and the loss of motor efficiency was quantified.

COMPARATIVE ANALYSIS OF SIX PHASE INDUCTION MOTOR

In recent years, AC induction motors have replaced DC motor. The most important reason for this is that DC motors have a mechanical brush and commutator system that is subject to wear and tear over time. While DC motor drivers need a lot of maintenance due to this system, induction motors do not require almost any maintenance since this system is not available. In recent years, technological advances in the field of multiphase induction motors have led to a significant evolution. A lot of research has been done around the world and a lot of new and interesting developments have been reported to the literature. This paper provides information about six-phase induction. In addition, what kind of advantages the concept of multiphase provides and how this structure is formed contains information about them. The six-phase induction motor will be simulated through the MATLAB/SIMULINK package program and compare with three phase induction motor. Both motors were run in simulation using the same parameters. At the end of the simulation, current, moment and speed graphs of the six-phase induction motor and three-phase induction motor will be drawn according to time. The study also included equations used during modeling and equivalent circuits belonging to a six-phase induction motor. It has been graphically shown that a six-phase induction motor is more advantageous than a three-phase motor. For example, in six-phase induction motors, the transition time to a continuous state is shorter. In addition, while the frequency of torque vibration increases, its amplitude decreases, the current value of each phase decreases, the stator copper losses are less than the three-phase induction motor. In motors, usually the power needed is divided by the number of phases. So the more phases there are, the greater the power carrying capacity. Today, multi-phase induction motor drives are used in special applications such as electric vehicles, space technology, aerospace applications, as moving power on ships, electric trains, which require high reliability and power.

Active vibration control for GyroWheel based on sliding mode observer and adaptive feedforward compensator

This article proposes an active vibration control method for the GyroWheel to ensure the attitude stability precision of the spacecraft. The method includes sliding mode disturbance observer and adaptive feedforward compensator. First, considering the disturbance torque caused by rotor imbalance, the dynamic equation adopting complex coefficients is derived with synchronous disturbances. To reduce the influence of model parameter perturbation, a finite time sliding mode observer is designed to estimate the rotor imbalance owing to its robustness. An integrator for the switching term is introduced in the sliding manifold, which attenuates the chattering phenomenon. Then, the observed unbalanced torque is utilized to generate the reference compensation tilting angle, which is fedforward to the command value to offset the synchronous frequency current. A variable step size seeking algorithm is adopted to tune the feedforward compensator gain adaptively. Finally, both numerical simulations and experiments have verified the effectiveness of the active vibration control scheme, achieving clean vibration torque.

Influence of electrical part of traction transmission on dynamic characteristics of railway vehicles based on electromechanical coupling model

With the continuous development of rail transit industry and the acceleration of train speed, higher requirements are established for the operation quality of high-speed trains and the reliability of transmission system. In the process of train running, speed fluctuation and vibrations from various parts of the driving devices are common, which could be greatly affected by the traction torque. During traction transmission, the harmonic vibration torque exists in traction motor due to that the motor is connected with non-sinusoidal alternating current. In order to study the vibration influence of the electrical component of traction transmission system on the rail vehicles, i.e., bogie and car-body, an electro-mechanical coupling dynamic model for rail transit vehicles was established by explicitly incorporating the electric-induced traction into the transmission model. The dynamics responses of the vertical, lateral and longitudinal acceleration on vehicle components, such as axle box and car-body were quantitative analyzed. By comparison with field test, it was observed that there was a vibration peak of 12-times of the fundamental rotor frequency on the bogie frame and axle box, which existed at conditions of traction, uniform speed and braking. However, the vibration acceleration exhibit nearly little difference with or without traction force, especially at low frequency domain < 100 Hz.

Harmonic Electromagnetic Torque Analysis of Turbo-Generators by a Novel Lumped Magnetic Parameter Method and Finite Element Method

– Because of the absence of theoretical method for harmonic electromagnetic torque calculation, based on the relationship between the electromagnetic torque and the electromagnetic power, a new lumped magnetic parameter method (NLMPM) for harmonic electromagnetic torque calculation is introduced in this paper. Then based on the NLMPM, the effect of damper winding on harmonic component of the electromagnetic torque is investigated, including the existence of damper winding and the material alteration of damper winding. After that, to test the effectiveness of the theoretical analysis, the finite element models of a 1400MVA and a 30kVA turbo-generator are built up. Also, the experimental data proves the correctness of finite element models. The results achieved by the NLMPM and the finite element method (FEM) have a very good agreement. The concrete error between the NLMPM and the FEM at small current asymmetrical degree and big current asymmetrical degree is given respectively. The effect of damper winding on harmonic component of the electromagnetic torque is studied from a totally new perspective, as well. The theoretical method introduced in this paper can accurately help detect the harmonic electromagnetic torque vibration according to the lumped magnetic parameters.

Measurement of Stress Waves Propagation in Percussive Drilling.

This work describes the results of a test campaign aimed to measure the propagation of longitudinal, torsional, and flexural stress waves on a drill bit during percussive rock drilling. Although the stress wave propagation during percussive drilling has been extensively modeled and studied in the literature, its experimental characterization is poorly documented and generally limited to the detection of the longitudinal stress waves. The activity was performed under continuous drilling while varying three parameters, the type of concrete, the operator feeding force, and the drilling hammer rotational speed. It was found that axial stress wave frequencies and spectral amplitudes depend on the investigated parameters. Moreover, a relevant coupling between axial and torsional vibrations was evidenced, while negligible contribution was found from the bending modes. A finite element model of the drill bit and percussive element was developed to simulate the impact and the coupling between axial and torsional vibrations. A strong correlation was found between computed and measured axial stress spectra, but additional studies are required to achieve a satisfactory agreement between the measured and the simulated torque vibrations.

Study on the JH-2 Model Parameters for Metro Shield Cutting Reinforced Concrete Pile

In order to investigate the application of JH-2 (Johnson-Holmquist-2) constitutive model in concrete, a series of parameters study have been conducted to evaluate the JH-2 model in C30 concrete. The finite element analysis software ABAQUS is utilized to simulate the compression test of the three-dimensional standard concrete test based on the ALE adaptive mesh and the damage failure criterion of element deletion function. The numerical analysis of 3D concrete pile foundation and simplified shield machine cutter head to simulate shield cutting pile is established. Analyzing the numerical simulation and construction data, the key points of the shield machine cutting pile are illustrated. Research shows that: (1) JH-2 constitutive model can be used to simulate the concrete cutting. (2) The better damage parameters have been represented and verified against the results of experiments, which are D1 = 0.6 and D2 = 0.1 in the JH-2 model of C30 concrete. (3) In the simulation example of concrete compression and cutting pile, the failure form of concrete is brittle failure, and the non-linear characteristics of concrete has been observed. (4) The simulated torque vibration of the cutter head is relatively large than actual pile cutting, and the actual shield machine cutting pile construction should have a low rotation speed and low propulsion speed.