Torque Vibration Research Articles

Optimization Study of Poles-slots Combination of Large Capacity Offshore HTS Wind Generator Based on Ansys Maxwell

The superconducting wind turbine has the advantages of large capacity, high power density, small size, low weight, high efficiency and low cost. In the case that the rotor has many poles, how to choose the number of slots of stator is very important to the performance of the motor. This paper took 10 MW Offshore HTS Wind Generator as an example, analyzed the influence of different poles-slots combination on the performance of the generator, and finally determined a set of relatively reasonable scheme. The simulation results showed that this scheme can effectively reduce the high harmonic of no-load counter electromotive force and improve the induced voltage distortion rate and torque vibration, significantly improve the motor performance. It is of guiding significance for the structural optimization of superconducting motors.

Load mitigation and wind power maximization of a HESG-based wind conversion system

This article discusses the control optimization of a hybrid generator-based wind conversion system (WCS). The optimization issues consider the maximization of the extracted wind power for the below-rated wind speeds and the load mitigation for high wind speeds. To do so, a DC/DC converter is used to realize the steady-state control of the generator's velocity through the adjustment of the excitation current, leading to maximization in the wind extracted power. As for the high wind speeds, a H∞ regulator implemented for the pitch control and a filter smoothing for the pitch angle reference are used to mitigate the load. Thanks to the implemented control strategy, the amplitude of the fluctuation of the bending moment was reduced by about 20% and the turbine torque vibration was reduced by 66% in comparison with other existing works from the literature conducted on the same wind turbine. The velocity controller is three times faster than the baseline controller and allows for increasing the wind extracted power by 6%. In this research, an integrated simulation platform, combining the electrical, mechanical, and aerodynamic aspects of a WCS, is set up. The space harmonics of the generator, the commutation effects of the power converters, the flexible coupling between the wind turbine's mechanical elements, and the aerodynamic interactions are taken into account. Finally, the control of the WCS in its full operating range is considered. The mechanical and aerodynamic data from the 1.5 MW WindPACT turbine available in the Fatigue, Aerodynamics, Structures, and Turbulence simulator are used for the simulations.

Field Oriented Control-Based Reduction of the Vibration and Power Consumption of a Blood Pump

Power quality and energy efficiency are of great importance in motor control. The motor of any medical device needs to have a smooth torque and minimal vibration in order to maximise its energy efficiency and patient comfort. Furthermore, in rotary blood pumps, excessive energy wasted due to vibration is converted into uncontrolled movement of the mechanical parts and thus could reduce the life of the motor-pump. Besides mechanical or hydraulic origin, one of the causes of vibration in any pump is torque ripple resulting from motor phase commutation. In this paper, using relevant equipment, two extreme scenarios were examined for vibration and electrical efficiency comparison due to power quality in a blood pump: one trapezoidal control with a trapezoidal phase current output; the other a field oriented control (FOC) with a non-distorted sinusoidal phase current. The test motor-pump was the Arteriovenous Fistula Eligibility (AFE) System that is used prior to haemodialysis. The trapezoidal technique was implemented utilising the Allegro a4941 fan driver (Allegro Microsystem, 2012), and the FOC technique was implemented using the Texas Instrument digital signal processor (TMS320F28335). The aim was to reduce the energy wasted over vibration, and to achieve smooth operation of the AFE System. Vibration was measured with a one-axis accelerometer; results showed considerably lower vibration due to less current ripple associated with the FOC control as well as lower power consumption.

Vibration reduction of switched reluctance motor under static eccentricity with optimised current harmonic

Aiming at the problems of severe vibration of switched reluctance motor (SRM) and the transfer of the peak vibration caused by newly produced radial magnetic force under static eccentricity (SE), this study proposes a vibration reduction method for SE. First, the analytical relationship between the radial magnetic force harmonics and the current harmonics is derived. 2D Fourier decomposition is used to analyse the temporal–spatial characteristics of force harmonics and the vibration response under SE. Then the expression of the force harmonic, which causes the peak vibration, is used as the optimisation function of current harmonics. According to the analyses in this study, it is difficult to consider vibration reduction and torque simultaneously by single-order current harmonic optimisation and the unreasonable optimisation range of current will seriously affect the output performance. Therefore, a reasonable optimisation range is set based on the above conclusions and the first five order current harmonics are optimised to improve the effect of vibration suppression further. The results of the finite element simulation verify the effectiveness of this method.

Starting Pulse Vibration Torque Analysis of Aviation Variable Frequency Asynchronous Motor Based on Low-Frequency Step-Down Starting Methods

The more electric aircraft provides 115 V/360~800 Hz variable frequency power supply for the variable frequency asynchronous motor, and the motor operation characteristics change with the power frequency variation. It causes the starting pulse vibration torque with the low-frequency power supply (360 Hz) to increase greatly and the mechanical shock and fatigue damage. Therefore, this paper proposes step-down starting method with the low-frequency power supply. Based on the electromagnetic principles generated by the starting pulse vibration torque, this paper uses a novel method of simulation data fitting to establish an approximate model of the starting pulse vibration torque. The parameter design formulas of the low-frequency step-down starting methods, including the reducing voltage, the series resistance, and the series inductance are proposed. The effectiveness of the different methods are verified, and the performance is compared through the simulation. The experimental verification of a small power asynchronous motor is completed. The simulation and experiment results show that the low-frequency step-down starting methods effectively reduce the starting peak torque, and also suppress the shock impact of starting current on the power supply.

Grain Refinement in Aluminium 1xxx Series as Effect of Vibration Torch Welding

Grain refinement is the best way to improve the mechanical properties of fusion welds of the aluminium. The grain refinement was thereby found to be strongly dependent upon the aluminium chemical composition, where the pure aluminium has the highest grain refining efficiency. In order to increase the strength of the weld area is carried out by TIG welding with vibration on the torch which aims to obtain a smoother welded grain deposit so that its strength will increase. Theoretically, smoothing of the weld grain deposits occurs due to the welding along with with the torch vibrations arising from the peak pressure generation, the development of shear stress, the density power and the presence of laminar flow around the dendritic arm resulting in the intersection of the dendritic arms which smooths the grains. To observe the effect of the frequency and amplitude of the torch vibration in welding to refine the welded grain deposits, the research conducted with 5 Hz and 10 Hz torch vibration and torque vibration amplitude (0.25; 0.50; 0.75; 1.10; 1.60 and 2.00) mm and welding speed of 100 mm/minute and 200 mm/minute, respectively. As a comparison of the extent to which the effect or effectiveness of vibration on the torch on the weld deposit grain size produced, welding without vibration with welding speed of 100 mm/minute. Increase the welding speed will reduce grain size; on the other hand, increase the frequency have affected different grain size. Meanwhile, increase the amplitude to 0.75 mm will reduce the grain size then the grain size will unstable with increasing amplitude.

Observer‐based compensation control of servo systems with backlash

AbstractFor compensating backlash phenomenon in servo systems, the authors propose an observer method in this paper to estimate both system states and vibration torque before controller design. First, a systematic scheme is given to obtain plant parameters, which is very important in observing system states. This is a parameter estimation principle that gives a crude estimation and computes the differences between the crude and true values. As a result, the precise value of the parameters is obtained by adding together the crude value and the difference. Then, based on the precise estimated parameters, an extended state observer (ESO) is designed to obtain feedback and feedforward signals. Consequently, robust compensation control is achieved by designing an output feedback controller, consisting of a feedback term and a feedforward term. Finally, in order to validate the proposed approach, extensive experiments are performed on a practical servo system with backlash nonlinearity.

Magnetization State Manipulation Method to Reduce Back Electoromotive Force in High Speed Region of Variable Flux PMSMs and a Study of Vehicle Torque Vibration

Magnetization State Manipulation Method to Reduce Back Electoromotive Force in High Speed Region of Variable Flux PMSMs and a Study of Vehicle Torque Vibration

ОЦЕНКА МОЩНОСТИ СУДОВЫХ ЭНЕРГЕТИЧЕСКИХ УСТАНОВОК

In modern conditions developing methods of functional diagnostics of the technical state of internal combustion engines, which are based on monitoring of power indicators, is of current importance for ship power plants (SPP). In terms of inability to estimate the plant’s capacity during the voyage, it was proposed to develop methods for its indirect estimation. Measuring the angular acceleration of the crankshaft of the going up engine is considered the well-known and most reliable method for estimating the power plant capacity. There has been presented a device flowchart for estimating the capacity of a SPP based on the ratio of fuel and air consumption. In this case the restriction is that the method can be employed only for the SPPs equipped with gearboxes with the function of discontinuity of the shaft line due to a great moment of inertia of the propeller submerged into the water. There has been suggested the analysis of the ratio of fuel and air consumption at a certain frequency of shaft rotation, as a versatile way to evaluate capacity of SPPs with internal combustion engines. It has been stated that the SPP energy parameters can be evaluated using the analysis of the torsional-vibrational system values. To this end, it was suggested to use a relatively new method of processing diagnostic information based on wavelet analysis using sensors of torsional vibrations installed on fixed supports and having a function to determine angular deformations of the shaft line caused by the rotation torque vibrations. A distinctive feature of the wavelet analysis is a high sensitivity in determining short-term high-frequency signal fluctuations. There is given an example of recording the amplitude values of torque when using this method. Amplitude values have been calculated on the basis of Morlet function, according to Hölder's indicator, at the SPP engine rotation speed 900 rpm for four turns of the engine crankshaft.

RTC (reaction torque compensated) induction motor and its open-loop control

Rapid change of the rotating speed of an induction motor causes large reaction torque or excessive vibration of the system base. This paper proposes a passive reaction torque compensated (RTC) induction motor considering the dynamic characteristic of open-loop speed control with a variable frequency drive. RTC mechanism converts the reaction torque into the dissipative inertial energy of the rotary stator and the potential energy of the torsion spring torque so that a part of the reaction torque or the spring torque is transmitted to the system base. First, dynamic equation and simulation model for the RTC induction motor are introduced and verified with experiments. The acceleration response of an induction motor with variable speed drive is approximated as first-order ordinary differential equation. Then, the RTC mechanism such as spring and additional inertia are designed considering derived acceleration response or torque profile. Then, an experimental set-up and its control system for the RTC induction motor are built. Finally, effectiveness of the RTC induction motor is verified comparing open-loop speed control of both RTC and conventional induction motor.

Synchronization and vibratory synchronization transmission of a weakly damped far-resonance vibrating system.

The self-synchronization of rotors mounted on different vibrating bodies can be easily controlled by adjusting the coupling parameters. To reveal the synchronization characteristics of a weakly damped system with two rotors mounted on different vibrating bodies, we propose a simplified physical model. The topics described in this paper are related to coupling dynamic problems between two vibrating systems. Both synchronization and vibratory synchronization transmission of the system are studied. The coupling mechanism between the two rotors is analyzed to derive the synchronization condition and the stability criterion of the system. The vibration of the system is described by an averaging method that can separate fast motion (high frequency) from slow motion (low frequency). Theoretical research shows that vibration torque is the key factor in balancing the energy distribution between the rotors. Taking the maximum vibration torque (MVT) as a critical parameter, we investigate the synchronization characteristics of the vibrating system in different cases. The curve of the maximum vibration torque (MVT) versus coupling frequency is divided into several parts by the coupling characteristic frequency and the input torque difference between the rotors. Simulations of the system with coupling frequencies from different parts are carried out. For the system with rotational frequencies larger than the natural frequencies, the coupling characteristic frequency or characteristic frequency curve should be considered. When the coupling frequency is close to the characteristic frequency or the vibration state is close to the characteristic frequency curve, self-synchronization of the two rotors can be obtained easily. Under certain conditions when the coupling effect between the rotors is strong enough, the rotors can maintain synchronous rotation even when one of the two motors is shut off after synchronization is achieved, which is called vibratory synchronization transmission. Vibratory synchronization transmission of the system occurs in a new synchronous condition, and the phase difference between the rotors takes on a new value, that is, the system approaches a new synchronization state.

Vibration Torque Suppression for Magnetically Suspended Flywheel Using Improved Synchronous Rotating Frame Transformation

Synchronous vibration, a common issue in active magnetic bearing (AMB) system, is mainly caused by mass imbalance of the rotor. It comes with high‐power consumption and serious impact on the housing base, dramatically degrading the performance of AMB. Magnetically suspended flywheel (MSFW), which owns a flat rotor and consequently shows strong gyroscopic effects even at low operating speed, requires additional attention not only for suppressing the synchronous vibration but also for maintaining the overall stability faced with the coupled dynamics. In this work, in order to suppress the vibration torques in MSFW with significant gyroscopic effects, an improved synchronous rotating frame‐ (SRF‐) based control method is proposed. The proposed method introduces the compensation phase for stability adjustment and aims at simultaneously suppressing the synchronous components in the coupled axes. Firstly, the vibration torque model of MSFW is established, and the baseline control strategy for suspension and gyroscopic effects restrain is derived. Then, the principle and implementation of the improved SRF‐based vibration torque method are analyzed, which aims at suppressing the synchronous vibration torques through attenuating synchronous components in coil currents. Moreover, the stability of the overall closed‐loop system is analyzed. Finally, the effectiveness of the proposed method is verified through simulation and experimental results.

Study of Proposals and Torque Vibration Reduction Structure of the 16-pole 18-slot IPM Motor for Mild Hybrid

The efficient construction method of mild hybrid is to minimize the mechanical loss by directly connecting the engine and the assist motor. The shape of the motor to be directly connected to the engine output shaft has a flat structure with a diameter of 250 to 300 mm and an axial length of 60 to 90 mm, and various multipolar PM motors have been proposed in order to obtain high output and high power generation. As a slot pole combination, it is known that a combination of 8-9 is good, but it was said to be impractical due to the problem of magnetic imbalance due to eccentricity. For large diameter motors, it is possible to configured with 16-18, twice the basic configuration. In this paper, we propose an IPM motor with 16 - 18 - combination for mild hybrid considering performance and low vibration during startup and power generation. The usefulness of 16 poles and 18 slots combination and the cogging torque · torque ripple reduction structure were clarified by finite element analysis.

Synchronization behavior of a weakly damped far-resonance vibrating system

In order to reveal synchronization characteristics of a weakly damped system with two rotors mounted on different vibrating bodies, we propose a simplified physical model. Vibration of the system is discussed by the average method, which can separate fast motions (high frequency) from slow motions (low frequency). Theoretical research shows that vibration torque is the key factor to balance the energy distribution between rotors. For the system with rotational frequencies larger than the nature frequencies, the coupling characteristic frequency or characteristic frequency curve should be considered. As the coupling frequency is close to the characteristic frequency, or the vibration state is close to the characteristic frequency curve, self-synchronization of two rotors can be obtained easily.

A Multi-objective Optimization of Switched Reluctance Motor using a Hybrid Analytic-ANFIS Model Considering the Vibrations

Switched reluctance motors have a rugged construction which makes them suitable for many applications. But, high torque ripple, vibration, and acoustic noise are the main drawbacks of them. In this paper, the vibration is considered in optimization besides the other desired considerations. The radial force is the main origin of vibration in switched reluctance motor, and a torque-to-force ratio is introduced for considering the low vibration in optimization. Also, modeling of switched reluctance motor is somehow challenging. In this paper, a hybrid method based on analytic and adaptive-neuro-fuzzy inference system methods is presented for modeling SRM and the obtained static characteristics are used in a dynamic simulation method. Discussion on simulation results is presented at the final part of the paper which shows the lower vibrations lead to bigger air gap length; so, to prevent the deterioration of other features, an optimization should be done. A multi-objective particle swarm optimization is used to find the dominant design, and the best design is obtained by means of weighted cost functions.

Torsional Vibration Analysis of Hydro-Generator Set Considered Electromagnetic and Hydraulic Vibration Resources Coupling

The torsional vibration characteristics of the hydro-generator set considering the electromagnetic and hydraulic vibration resources coupling are studied. The moment of rotation consists of water flow driving and magnetic torques caused by the air gap magnetic field in the generator rotor in the case of ignoring the mechanical friction. A coupling torque vibration model of hydro-generator shaft system was established. The model considered the coupling action of hydraulic and electromagnetic excitations, as well as the elastic effect of rotor spiders. The influences of the rotor moment inertia, rotor stiffness, and mass of turbine water added into the torsional natural vibration of the unit shaft system were studied. The effect of hydraulic excitation frequency on torsional vibration response was also investigated. The frequency response curves of shaft torque, torsional vibration angle, and electromagnetic torque were presented. The electromagnetic and hydraulic coupling resonance was studied when hydraulic excitation frequency was equal to zero and first-order frequencies. The excitation electric current and internal active power angle on torsional vibration was further analyzed. This study provides an analysis model and method considering the coupling of electromagnetic and hydraulic vibration resources for design and stable operation of water turbine generator sets.

Kinetic characteristics analysis of a new torsional oscillator based on impulse response

For reducing the sticking or stick–slip phenomenon, this paper proposed a new torsional oscillator which could produce a circumferential torque vibration in the drilling process. Based on the working principle and fundamental structure, the generation mechanism of torsional vibration and the relationships of the mechanical parts are derived. Then, the dynamic model is established according to the drilling operation condition. With this, the further analysis of changing relationship between the inlet flow and torque is studied. The angular displacement and velocity of the valve body are analyzed according to the dynamics theory models. With the combination of the theoretical analysis model, the parameter studies are carried out by numerical example calculation. Finally, experiment test is conducted to identify the accuracy and reliability of the calculation method under the corresponding working conditions. The results show that with the constant pressure the average torque is proportional to the inlet flow. However, while the inlet pressure is invariable, the collision period is inversely proportional to the inlet flow, and the angular displacement and velocity are proportional to the inlet flow. The research results can provide references for the design and application of the torsional vibration tools, which is potential and significant in drilling engineering.

Active disturbance rejection control for electric power steering system with assist motor variable mode

The steering torque of automobile EPS steering system is significant for driving steering control and good driving feel. Servo motor control and external interference moment are the core factors affecting EPS steering system. With the advancement of automotive technology, the requirements of EPS control technology have been gradually improved, and the driving and handling of vehicles at high speed have become the key issues. For the current EPS steering system at high speed vibration and steering feel, active disturbance rejection EPS torque control method is proposed, EPS variable mode controller was developed. The control of the variable mode is verified by experiment and the vibration torque from the road is controlled, determine the control frequency of 30 KHz, the amount of current fluctuation is the smallest. The ADRC (active disturbance rejection controller) technology is used to suppress the interference of the road surface, finally, the validity of active immunity is verified by bench test. Steering wheel vibration torque can be reduced by an average of 28.5% to 33.3%.

Upon drive dynamics of vibratory machines with inertia excitation

Dynamics of the vibration machine taking into account the elasticity of coupling of the unbalance vibration exciter with a limited- power electric motor is considered. A solution describing the relative torsional oscillations of the vibration exciter and motor rotors in steady (near-steady) motion modes and the formula for vibrational torque was obtained. The above mentioned dependencies are also valid for the case of motor speed “sticking” in the natural frequency region of the vibration machine. The correlation between the vibrations of the unbalance drive and the vibration machine bearing body is established. Recommendations for avoiding resonant vibrations of the vibration machine drive are formulated.

Improved condition monitoring technique for wind turbine gearbox and shaft stress detection

Condition monitoring has been widely used to detect mechanical and electrical faults of wind turbine in order to avoid any potential catastrophic failures, reduce operational and maintenance cost, and enhance the reliability and availability of the equipment. Although several papers about wind turbine condition monitoring can be found in the literatures, adopting a reliable and cost-effective technique for wind turbines that usually experience severe mechanical stress due to the harsh weather conditions they are exposed to is still challenging. Although statistical studies show that gearbox failure rate is low, the resulted downtime and the replacement or repairing cost is substantial. This study introduces an improved technique to monitor the condition of the wind turbine gearbox based on gearbox vibration and shaft torque signatures analyses. In this context, a test rig that emulates real wind turbine operation has been developed to analyse the behaviour of wind turbine under various mechanical fault levels. Shaft torque and mechanical vibration signals are detected using high-resolution sensors and are analysed using two signal processing techniques: wavelet and order analyses to examine the impact of investigated fault levels on the wind turbine drive train. Both signal processing techniques are compared based on their sensitivity to detect incipient fault levels.