Showing papers on "Damping torque published in 2003"

Optimal torque control of fault-tolerant permanent magnet brushless machines

Abstract: Describes a novel optimal torque control strategy for fault-tolerant permanent magnet brushless ac drives operating in both constant torque and constant power modes. The proposed control strategy enables ripple-free torque operation to be achieved while minimizing the copper loss under voltage and current constraints. The utility of the proposed strategy is demonstrated by computer simulations on a five-phase fault-tolerant drive system.

Study on Damping Reduction Factor for Buildings under Earthquake Ground Motions

Abstract: This paper discusses the rationality of the design force and damping reduction factors adopted by a few seismic design provisions for buildings with and without added passive energy dissipation systems. The issue will first be pointed out that the damping reduction factors adopted by those provisions are derived from the effects of viscous damping on displacement responses, but are used to reduce the design force of buildings. Statistical results from 1053 ground motions recorded in the U.S. show that it may lead to unconservative results, especially for systems with damping ratios greater than 10% and periods longer than 0.15 s. Furthermore, although there is no doubt that the additions of extra damping to a structure will always reduce the displacement responses, many documents argue the effect of added damping to reduce the force responses of the buildings. Therefore, this paper also addresses the effects of viscous damping on the inertial force and elastic restoring force in order to use the damping reduction factors correctly. Results of this study suggest that if the damping of structures comes from the hysteretic response of the building, the design force of the structures should be the inertial force and the damping reduction factors should be derived from the acceleration responses. Otherwise, if the additional damping of structures comes from the added energy dissipation devices, the design force should be the restoring force and the damping reduction factors should be derived from the displacement responses.

Optimum pole arcs for a switched reluctance motor for higher torque with reduced ripple

Abstract: In this paper, the results of a two-dimensional (2-D) finite element (FE) analysis carried out on a 8/6 switched reluctance motor with a view to arrive at the optimum pole arcs for the stator and rotor teeth are presented. The authors have put forward a new method for calculating the average torque for comparison of static torque profiles to identify the optimum one. In this new method, 15/spl deg/ of the static torque profile, where the developed torque is nearly constant is considered for calculating the average torque. Operating the motor in this range instead of the first quarter cycle of the static torque profile will ensure higher average torque with minimum ripple. This average torque is considered as the parameter for comparison of different torque profiles of various pole arcs for the stator and rotor. It is observed that the geometry with the existing stator pole arc of 20.2/spl deg/ and a changed rotor pole arc of 30/spl deg/, instead of the existing 23.5/spl deg/ will be the optimum for this motor, as it gives the highest average torque with the minimum ripple.

Method and apparatus for motor control

Abstract: A closed-loop permanent magnet motor control method and system optimally partitions torque and flux-weakening currents to produce a desired torque without exceeding the capability of the DC source. A maximum limit for allowable torque current and a minimum threshold for the maximum torque current are determined, and the flux current is varied based at least in part on whether the maximum torque current limit is above or below the minimum threshold while operating in a flux-weakening region to compensate for the variability of the DC source voltage.

Method and system for controlling a motor

Abstract: A method of transitioning a motor from a torque control mode to a speed control mode includes providing the motor with a torque command to eliminate torque holes at the transition. A speed controller generates a speed error, which is used to generate two torque terms. The first torque term is proportional to the speed error, and the second torque term includes the integral of the speed error. A third torque term comprises a feedforward torque, which is added to the first two torque terms to generate the torque command.

Modeling of MR damper with hysteresis for adaptive vibration control

Abstract: This paper is concerned with structural vibration control using a semi-active magnetorheological (MR) damper. A simple mathematical model of MR damper is proposed to express its hysteresis effect of dynamic friction characteristics. The model can predict the damping force based on the inputs of velocity, internal state and input voltage to the MR damper. The model can also he used to obtain an inverse dynamic model to analytically determine the necessary input voltage so that the desirable damper force could be added to the structure in an adaptive manner. In conjunction with the LQG control which gives the desired target damping force, the total adaptive algorithm can work effectively even if the MR damper has uncertainty and changeability, which is validated in numerical simulations.

Vibration Damping by Friction Forces - Theory and Applications

Abstract: In this paper, we deal with the vibrational behavior of mechanical structures interconnected by contacts with friction. The focus is set on the utilization of friction forces that are generated in the contact interfaces with the objective to increase damping and to reduce vibration amplitudes in order to prevent structures from failures owing to high resonance stresses. We present a comparison and classification of different contact models that are most commonly used, including the derivation of a three-dimensional contact model under consideration of rough surfaces. We give different solution methods for problems with non-linear friction elements. The effectiveness of friction damping devices is pointed out by a single-degree-of-freedom friction oscillator, beam-like structures with frictional interfaces and different underplatform dampers in turbo-machinery applications. It can be shown that in many practical applications friction damping devices provide a remarkable decrease of vibration amplitudes.

Processes of determining torque output and controlling power impact tools using a torque transducer

Abstract: An impact tool having a control system for turning off a motor at a preselected torque level.

Predictive direct torque control for the PM-synchronous machine

Abstract: The paper shows that a predictive digital control combined with the principle of the direct torque control leads to an excellent dynamic behavior of the permanent magnet excited synchronous machine and is a real alternative to the classical field orientated control. The advantages are the constant switching frequency and the predictable torque ripple. The set up times of the torque are reduced compared with the classical control. The application in servo-drives in which the rotor position is always measured can be easily realized using a commercial DSP. Numerous simulations and measurements confirm the theoretical work.

Experimental study of aerodynamic and structural damping in a full-scale rotating turbine

Abstract: Damping in turbomachinery blades has been an important parameter in the study of forced response and high-cycle fatigue, but because of its complexity the sources and physical nature of damping are still not fully understood. This is partly due to the lack of published experimental data and supporting analysis of real rotating components. This paper presents the results of a unique experimental method and data analysis study of multiple damping sources seen in actual turbine components operating at engine conditions. The contributions of both aerodynamic and structural damping for several different blade vibration modes, including bending and torsion, were determined. Results of the experiments indicated that aerodynamic damping was a large component of the total damping for all modes. A study of structural damping as a function of rotational speed was also included to show the effect of friction damping at the blade and disk attachment interface. To the best of the authors' knowledge, the present paper is the first report of independent and simultaneous structural and aerodynamic damping measurement under engine-level rotational speeds.

Analysis of subsynchronous resonance with three level twelve-pulse VSC based SSSC

Abstract: The paper presents the analysis and simulation of a series compensated system with a static synchronous series compensator (SSSC) as a part of the total compensation. The objective is to investigate the subsynchronous resonance (SSR) characteristic of the combined system. The IEEE first benchmark model (FBM) is considered for the analysis. The active series compensation is provided by a three level twelve pulse SSSC. The modelling and control details of a three level voltage source converter (VSC) based SSSC are discussed. The analysis of SSR with SSSC is carried out based on a frequency domain method, eigenvalue analysis and transient simulation. The frequency domain method considers the D-Q model of SSSC for the computation of damping torque for a quick check in determining torsional mode stability.

Torque control method for an internal combustion engine

Abstract: A torque control method for an internal combustion engine for computing a required torque and controlling a throttle motor on the basis of the required torque includes computing a first required torque on the basis of a depression amount of an acceleration pedal and an engine speed, and computing a second required torque by multiplying an output value of a gradient limit function by an output value of a time delay function. The output value of the gradient limit function is determined on the basis of the first required torque, an acceleration pedal depression amount, an engine speed, and a shift range. The output value of the time delay function is determined on the basis of the shift range.

Method and apparatus to regulate loads

Abstract: A method and apparatus for use with a controller for controlling a machine wherein a torque reference value is provided, the method for identifying an error representative of the difference between the torque reference value and the torque applied to the machine and using the error value to modify machine operation, the method comprising the steps of obtaining feedback current values corresponding to the currents provided to the machine, mathematically combining the feedback current values to generate an error value, mathematically combining the error value and the torque reference value to generate a torque command value and using the torque command value to control the machine.

An improved current control method for torque improvement of high-speed BLDC motor

Abstract: The BLDC (brushless DC) motor is characterized by linear torque to current and speed to voltage. It has low acoustic noise and fast dynamic response. Moreover, it has high power density with high proportion of torque to inertia in spite of small size drive. However, at high-speed operation, torque and speed response characteristic is deteriorated by the motor inductance components in stator windings. It is difficult that the BLDC motor is used to the industrial application requiring a wide range of operating speeds. Phase advance angle control method of different methods used to improve torque and speed response is used widely at high-speed operation. However, conventional phase advance angle control method was considered about forward motoring mode. Therefore, position information error of rotor that reverse motoring mode has phase lag angle of double comparing with forward motoring mode is occurred. Consequently, torque performance is destroyed significantly. In this paper, a control method using adjustment of the phase advance angle is proposed. This proposed method improves the torque and speed response characteristic by minimizing delay of current at high-speed operation. Simulated results prove the effectiveness of the proposed method through comparison with the conventional control method.

Electromagnetic shunt damping

Abstract: A method for electromagnetic shunt damping (EMSD) is presented in this paper. Compared to piezoelectric shunt damping, the proposed EMSD vibration controller has a number of benefits. It requires small shunt voltages, can provide large stroke and can dampen larger mechanical structures. A passive control strategy is validated through experimentation on a simple electromagnetic mass-spring-damper system. Theoretical results are also presented.

Drive controller of hybrid working machine

Abstract: PROBLEM TO BE SOLVED: To provide a drive controller of a hybrid working machine capable of reducing fuel consumption and improving power generating efficiency. SOLUTION: The drive controller comprises a pump absorbing torque controller 30 for controlling input torque to a hydraulic pump 17, and a motor/generator control means (21, 38) for controlling an operation of a motor/generator 20 disposed torque-transmittably with respect to an engine 16 for driving the hydraulic pump 17. The pump absorbing torque controller 30 sets the maximum value of the input torque at a predetermined value according to a specific operating form determined by operation form determining means (21, 44-49). The motor/generator control means (21, 38) controls the operation of the motor/generator 20 so as to output a regenerative torque according to the deviation between an output torque value of the engine 16 obtained by referring to an actual rotation speed detected by a rotation speed sensor 27 and the maximum value of the input torque set at the predetermined value. COPYRIGHT: (C)2005,JPO&NCIPI

Vehicle fast torque coordination

Abstract: Rapidly changing torque demand is coordinated in an automotive vehicle having an engine and at least one motor. An engine base torque level indicating slowly changing torque produced by the engine is received. A motor torque is determined as a difference between a fast desired torque and the engine base torque level. An engine fast torque is determined as a difference between the request for fast desired torque and the motor torque. The motor torque is determined as a motor torque request and the engine fast torque is determined as an engine torque request.

Torque controlling apparatus and method for hybrid vehicle

Abstract: In torque controlling method and apparatus for a hybrid vehicle, a vehicular propelling torque transmitted to the driven wheels is controlled under a predetermined torque distribution condition, a motor is made to perform a power running by supplying a generated electric power obtained as a result of a drive of a generator by the engine to the motor, an engine torque is distributed into both of a clutch transmission torque transmitted to the driven wheels via the clutch and a generation torque transmitted to the generator; and both of a clutch rate of the clutch and the generation torque of the generator are controlled on the basis of at least a vehicular velocity.

Control of powertrain smoothness using output torque sensing and input torque control

Abstract: An automatic transmission ratio shift and shift feel control system and method for a powertrain having an engine, multiple-ratio gearing controlled by friction elements actuated by hydraulic pressure, an output shaft torque sensor producing a signal representing the magnitude of current output torque, an electronic controller for controlling the target output torque based on the current output torque, increasing the torque capacity of the oncoming friction element and decreasing the torque capacity of the offgoing friction element after a gear ratio change is initiated. During the inertia phase of the ratio change, the controller controls the engine speed to follow a predetermined rate of change of input speed. The strategy employs an electronic throttle and closed loop engine torque control and closed loop engine speed control at various phases of the gear shift, to improve shift feel. Various engine parameters, including throttle position, ignition timing, engine air-fuel ratio, and engine airflow, control engine torque and speed, are used to control input torque or input speed, depending upon the shift phase.

Vibration damped flexible circuit for use in a hard disk drive

Abstract: A method and apparatus for damping vibration in a flexible cable for use in a magnetic disk drive apparatus. The vibration damping mitigates resonant oscillation of the flexible cable which would otherwise cause tracking errors by forcing the actuator of the away from the desired data track on a magnetic disk. A layer vibration damping material and one or more electrical leads are enclosed within a surrounding electrical insulator, the damping material being completely enclosed, while the leads have selected portions exposed to allow electrical connection devices.

Direct torque control strategy of permanent magnet synchronous machines

Abstract: Direct torque control (DTC) can be applied to all AC machine drives. The synchronous machine torque control, based on the DTC structure, permits to obtained high dynamic performances. This method is a concrete solution to robustness and dynamics problems find in other control structures. In this paper, we present a direct torque control strategy with minimization torque pulsations. We use a current sensor and an incremental position sensor. In order to control the torque, we use an hysteresis current controllers technique. This strategy consists on detecting the current at the voltage inverter input, and adjusted it to follow a reference with a high commutation frequency. The undesirable low harmonics are directly eliminated by the proposed position sensor. The obtained results are presented.

Device and method for controlling prime mover

Abstract: A device and a method for controlling a prime mover, the method comprising the steps of, when the angular acceleration (alpha) of the rotating shaft of a motor capable of outputting a torque on a drive shaft connected to drive wheels is raised and a slip occurs on the drive wheels, limiting the torque outputted to the drive shaft to an upper limit torque value (Tmax) led by using a map so related as to reduce the upper limit torque value (Tmax) as the angular acceleration (alpha) is increased and returning a torque limit to the original torque at a timing when the angular acceleration (alpha) becomes zero through a negative peak by the convergence of the slip, whereby since an angular acceleration acting direction matches a direction for acting the torque when the limited torque is returned, the torsion of the drive shaft can be suppressed to suppress vibration due to the torsion of the drive shaft.

Damping a hybrid stepping motor with estimated position and velocity

Abstract: It is well known that microstepping reduces the resonance behavior of stepping motors since the rotor moves in a sequence of very small steps. However, the under-damped nature of the motor does not change. In this paper, a scheme that uses microstepping and closed loop position control to stabilize and reduce resonance damping of the motor is proposed. The motor currents are controlled in a frame rotating synchronously with the excitation frequency. The d-axis current provides the torque to oppose the external load, and the q-axis current provides the transient torque to damp the motor. The motor velocity and position are estimated via an observer that tracks the angle of the motor back EMF voltage. The response of the closed loop system is independent of the external load level. Both simulation and experimental results have shown that the proposed control scheme is very effective in damping out the resonance of microstepping-controlled motors.

Power transmission device with automatic speed switching mechanism

Abstract: A power transmission device that is capable of automatic speed switching according to external load is disclosed, including a frame in which a transmission mechanism and a torque feedback mechanism are received. The torque feedback mechanism includes a torque resistant member so that when the load torque is smaller than its resistant torque, the speed reduction mechanism of the transmission mechanism is retained at a first, high-speed low-torque stage. When the load torque is larger than its resistant torque, a sliding ring of the torque feedback mechanism pushes a shifting gear so that the speed reduction mechanism is shifted to a second, low-speed high-torque stage. The speed reduction mechanism automatically shifts the speed reduction mechanism when the load torque increases or reduces such that the mechanical efficiency of the transmission device can be increased.

Reduction of equipment-generated damping in resonant column measurements

Abstract: Equipment-generated damping in the resonant column (RC) test due to interaction between the magnets and solenoids in the drive system causes a bias error in measured values of material damping ratio. Calibration and post-measurement corrections have been used to address this problem. In this study, an electromechanical model of the RC test is developed to aid in understanding the cause of equipment-generated damping and to identify possible real-time solutions. The model explicitly includes the signal source, which plays a key role in determining the amount of equipment-generated damping in the system. Furthermore, the model indicates that a current-mode source with large internal resistance rather than a more commonly used voltage-mode source is capable of reducing equipment-generated damping significantly in real time. A current-mode source is implemented using a voltage-to-current converter. The effectiveness of this approach is demonstrated using RC tests on aluminium, polymethyl methacrylate (PMMA), ...

Anti-bob system for cycles

Abstract: A control system is operable to selectably activate shock damping devices associated with a bicycle so as to eliminate bobbing encountered under extreme pedaling conditions. The system includes a crank axle torque detector which operates to detect a level of torque applied to a crank axle and provide a control signal corresponding to the level of torque. A shock damping device is coupled to the frame of the cycle, and functions to absorb and dampen mechanical shocks communicated to the frame. The shock damping device includes an activator for controlling its damping function. The activator is operable to receive the control signal from the crank axle torque detector and control the shock damping device in response thereto. The control signal may be an electrical or a mechanical signal.

Torque transmission device

Abstract: PROBLEM TO BE SOLVED: To easily reduce pulsation and variation in the torque of an engine SOLUTION: At starting the engine 12, the torque pulsation generated in the torque of the engine 12 is obtained from detected signals of a crank angle detection sensor 40 and an engine water-temperature detection sensor 38 A control unit 36 controls an MG 1 by a drive circuit 16MG1 so that damping torque having the same phase as that of the torque pulse is generated, and prevents the torque pulsation of the engine 12 from being transmitted to a ring gear 22 from a planetary carrier 24 COPYRIGHT: (C)2004,JPO&NCIPI

Torque sensing of finger joint using strain-deformation expansion mechanism

Abstract: /sup F/or dexterously performing object grasping and manipulation with multifingered hand of robot, sensing the finger joint torque is required. In general, the size of finger joint is quite small so that it is hard to realize the torque sensing. This paper proposes a novel mechanism, called the strain-deformation expansion mechanism, to sense the joint torque, which is small enough and fitted in the finger joint. By the torque sensing mechanism, the small joint strain-deformation used for torque sensing can be expanded without reducing the joint stiffness. In this paper, the torque sensing principle is addressed by analyzing the deformation of the sensing mechanism and the torques acting on the joint shaft theoretically. Then, the sensitivity of the sensing mechanism and its expansion rate of sensitivity are defined, and a design method for realizing the sensing mechanism with high sensitivity is discussed. Finally, some experiments with robot finger are performed to show the basic characteristics and the effectiveness of the proposed torque sensing mechanism.