Showing papers on "Damping torque published in 2002"

Minimization of torque ripple in SRM drives

Abstract: The torque pulsations in switched reluctance motors (SRMs) are relatively higher compared to sinusoidal machines due to the doubly salient structure of the motor. The magnetization pattern of the individual phases together with the T-i-/spl theta/ characteristics of the motor dictate the amount of torque ripple during operation. Both machine design and electronic control approaches have been used to minimize the torque ripple in SRMs. This paper presents an extensive review of the origin of torque ripple and the approaches adopted over the past decade to minimize the torque ripple. A hybrid torque-ripple-minimizing controller that incorporates the attractive features of some of the techniques developed in the past decade is presented along with simulation and experimental results.

DITC-direct instantaneous torque control of switched reluctance drives

Abstract: This paper presents an online instantaneous torque control technique for switched reluctance machines called direct instantaneous torque control. The method comprises two novel aspects. First, torque is estimated as a function of terminal quantities, i.e., flux linkage and phase current. Hence, torque estimation is independent of the rotor position. Secondly, high-bandwidth drive performance is obtained by implementing a digital torque hysteresis controller. Thus, the method works without torque profile functions and auxiliary phase commutating strategies. Therefore, the control algorithm offers a wide drive operating range without the use of a high-resolution shaft position sensor or sensitive position estimation techniques. Experimental and simulation results are presented in this paper.

A novel direct torque control for interior permanent magnet synchronous machine drive system with low ripple in torque and flux-a speed sensorless approach

Abstract: A novel direct torque control (DTC) scheme for an interior permanent magnet synchronous machine (IPMSM) is proposed in this paper, which features low torque and flux ripple and almost fixed switching frequency. The torque and flux ripples have been significantly reduced compared with those of the basic DTC reported in the literature. A speed estimation scheme is integrated with the proposed DTC scheme in order to achieve a fully sensorless high-performance IPMSM drive.

Free Vibrations of Taut Cable with Attached Damper. I: Linear Viscous Damper

Abstract: Free vibrations of a taut cable with an attached linear viscous damper are investigated in detail using an analytical formulation of the complex eigenvalue problem. This problem is of considerable practical interest in the context of stay-cable vibration suppression in bridges. An expression for the eigenvalues is derived that is independent of the damper coefficient, giving the range of attainable modal damping ratios and corresponding oscillation frequencies in every mode for a given damper location without approximation. This formulation reveals the importance of damper-induced frequency shifts in characterizing the response of the system. New regimes of behavior are observed when these frequency shifts are large, as is the case in higher modes and for damper locations further from the end of the cable. For a damper located sufficiently near the antinode in a given mode, a regime of solutions is identified for which the damping approaches critical as the damper coefficient approaches a critical value. A regime diagram is developed to indicate the type of behavior in each mode for any given damper location.

Engine torque ripple cancellation with an integrated starter alternator in a hybrid electric vehicle: implementation and control

Abstract: Integrated starter alternators (SAs) provide greater electrical generation capacity and the fuel economy and emissions benefits of hybrid electric automotive propulsion. The drive usually comprises a field-oriented induction motor or vector-controlled permanent-magnet motor coupled to the crankshaft of the engine directly or by a belt. These drives have high-bandwidth torque control and may be used for active cancellation of the significant ripple torque inherent in internal combustion engines. This paper presents an analytical model useful for the analysis of the combustion engine torque and describes a control system that uses observer-based high-fidelity torque feedforward and engine speed feedback to generate a disturbance input decoupling torque command for the SA to cancel the engine torque ripple.

Vibrations of a shallow cable with a viscous damper

Abstract: The optimal tuning and effect in terms of modal damping of a viscous damper mounted near the end of a shallow cable are investigated. The damping properties of free vibrations are extracted from the complex wavenumber. The full solution for the lower modes is evaluated numerically, and an explicit and rather accurate analytical approximation is obtained, generalizing recent results for a taut cable. It is found that the effect of the damper on the nearly antisymmetric modes is independent of the sag and the stiffness parameter. In contrast, the nearly symmetric modes develop regions of reduced motion near the ends, with increasing cable stiffness, and this reduces the effect of the viscous damper. Explicit results are obtained for the modal damping ratio and for optimal tuning of the damper.

Harmonic analysis of a magnetorheological damper for vibration control

Abstract: Semi-active control systems are becoming more popular because they offer both the reliability of passive systems and the versatility of active control systems without imposing heavy power demands. In particular, it has been found that magnetorheological (MR) fluids can be designed to be very effective vibration control actuators, which use MR fluids to produce controllable damping force. The objective of this paper is to study a single-degree-of-freedom (SDOF) isolation system with an MR fluid damper under harmonic excitations. A mathematical model of the MR fluid damper with experimental verification is adopted. The motion characteristics of the SDOF system with the MR damper are studied and compared with those of the system with a conventional viscous damper. The energy dissipated and equivalent damping coefficient of the MR damper in terms of input voltage, displacement amplitude and frequency are investigated. The relative displacement with respect to the base excitation is also quantified and compared with that of the conventional viscous damper through updating the equivalent damping coefficient with changing driving frequency. In addition, the transmissibility of the MR damper system with semi-active control is also discussed. The results of this study are valuable for understanding the characteristics of the MR damper to provide effective damping for the purpose of vibration isolation or suppression.

Online cage rotor fault detection using air-gap torque spectra

Abstract: This paper discusses use of air-gap torque spectra as a means of identifying faults in cage rotors. Being dependent on both stator and rotor currents, the torque is very sensitive to faults in the rotor. Through a comparative study using a detailed machine model and the standard dq model, the paper shows that the characteristic frequencies generated by a particular fault are preserved even if the standard dq model is used for estimation of air-gap torque. This is validated through a practical hardware implementation for online spectrum estimation of air-gap torque using TMS320C31, where several faulted cage rotors were used for study.

A new torque control method of a switched reluctance motor using a torque-sharing function

Abstract: A torque sharing function (TSF) method is one of the torque control methods that drives each phase of a switched reluctance motor so that the overall torque becomes a constant torque. The conventional TSF method defined the TSF only at a positive torque production region, which causes a poor torque-speed performance as the speed increases due to the delay of the current rising and falling time. This paper extends the definition region of the TSF to the negative torque region to have enough time to raise or decrease the current at the positive torque region. This extended TSF enables to increase the positive torque even in relatively high speed operation. Optimal determination of the TSF is investigated for various control objectives in mathematical and experimental ways.

Vibration control apparatus for vehicle having electric motor

Abstract: In a vibration control apparatus for a vehicle driven by an electric motor at least, a first target torque is calculated from a vehicle operating condition such as an accelerator opening, and a second target torque is calculated from at least a sensed motor speed by using a model H(s)/Gp(s) composed of a transfer characteristic H(s) which is greater than or equal to a transfer characteristic Gp(s) in an order difference between the order of a denominator and the order of a numerator. A torque control section controls the motor to bring an actual output torque of the motor closer to a command motor torque determined from the first and second target torque.

Variable Resistance Type Energy Regenerative Damper Using Pulse Width Modulated Step-up Chopper

Abstract: This paper describes a new technique for improving the damping property and efficiency of an energy regenerative damper It is intended for a linear DC motor type vibration damper to regenerate vibration energy efficiently. Normally a regenerative damper can regenerate vibration energy only at high speed motion. For low speed motion, the damper has nonlinear characteristics with dead zone and cannot regenerate energy. In order to overcome this problem, a step-up chopper is introduced between the actuator and the charging circuit. The energy is regenerated from low speed and low voltage actuator to high voltage charging circuit. This paper also proposes a new control technique to the step-up chopper by using pulse width modulated signals. The damper can change its damping coefficient and the energy can be regenerated more efficiently. The proposed damper is applied to an active mass damper system. A simple experimental setup is used to validate the proposed technique. The results show an increase in performance and energy regeneration as compared to the previously proposed regenerative damper.

Cylinder deactivation engine control system with torque matching

Abstract: An engine control system and method smoothes torque during transitions in a displacement on demand engine. A torque loss estimator generates a torque loss signal based on torque loss due to at least one of friction, pumping and accessories. A pedal torque estimator generates a pedal torque signal. An idle torque estimator generates an idle torque signal. A summing circuit generates a difference between the pedal torque signal and the idle torque and the torque loss signals and outputs a desired brake torque signal.

Nonlinear Robust Control of Torque Converter Clutch Slip System for Passenger Vehicles Using Advanced Torque Estimation Algorithms

Abstract: In this paper, a torque-estimation-based robust controller for passenger car torque converter clutch slip system is presented. The proposed robust controller uses only the measurements available from inexpensive sensors that are installed in current passenger vehicles for torque estimation and feedback control. A conventional full state observer along with a neural-network-based open-loop hydraulic actuator observer is designed to estimate the unknown driving load, and a neural-network-based turbine torque estimator considering the temperature of oil circulating the torque converter is developed for improved turbine torque estimation accuracy. The stability of the internal dynamics is also investigated, and the performance and robustness of the robust controller is validated by simulation studies.

Electromechanical steering, suspension, drive and brake modules

Abstract: Qualified chassis control is enabled by utilizing the modular alignment, load and torque concept described in this paper. The most advanced vehicle design incorporates mechanically identical wheel corners, each with individually powered and computer regulated propulsion, braking, steering, spring and damper functions. The suspension arms are mechanically attached to the body; all other interfaces are by-wire. In-wheel motors, actuators and a simple suspension geometry with no dive or lift suppression replace state-of-the-art powertrain, steering and suspension. Most actions and reactions between hub carrier and body is software controlled. If in-wheel drive is found inadequate, the modular build-up allows the addition of or conversion to conventional drivetrains. Algorithms regulating torque, vertical force and alignment determine the handling characteristics. Body leveling, pitch and roll control facilitates required ride comfort. Tyre rolling resistance and tyre wear is minimized by continuously optimizing wheel alignment and torque. This paper does not cover the electric power source, sensors or processing systems needed to run a vehicle equipped with described wheel corners.

Method and apparatus for motor velocity measurement compensation in electric power steering damping

Abstract: A method for generating a compensated torque command signal to be applied to an electric power steering motor is disclosed. In an exemplary embodiment, the method includes generating an assist torque command signal responsive to a measured vehicle speed and an input steering torque signal. An assist dependent damping torque signal is generated, the assist dependent damping torque signal responsive to the assist torque command signal, the measured vehicle speed and a compensated motor velocity output value of the electric power steering motor. The assist dependent damping torque signal is then subtracted from the assist torque command signal.

Torque fill-in for an automated shift manual transmission in a parallel hybrid electric vehicle

Abstract: An automated shift manual transmission (ASM) is utilized in a post-transmission parallel hybrid electric vehicle to take advantage of its high efficiency and lower cost compared to that of a fully automatic transmission with torque converter. However, a disadvantage of the ASM transmission is that the torque to the drive wheels is disrupted during gear shifts when the clutch is disengaged from the engine, resulting in degraded shift quality over an automatic transmission/torque converter combination. In the hybrid configuration presented here, an electric motor is utilized to provide torque directly to the drive wheels during gear upshifts when the engine is disengaged from the transmission. This torque applied during the shift is referred to as fill-in torque and, if properly applied, can emulate the continuous torque provided by the automatic transmission with torque converter. Effectively, the shift quality of an ASM transmission can be made to approach that of a fully automatic one via proper control of the fill-in torque and engine clutch slip. The amount of motor torque applied and the length of time it is applied are optimized by minimizing an objective metric of transmission shift quality. This paper presents such a control scheme, parameter optimization process, simulation results, and vehicle data that validates the simulation.

Haptic controller for road vehicles

Abstract: An electric assisted steering system for a motor driven road vehicle, having assist torque signal generating means which generates an assist torque signal for the steering system in response to the driver's applied torque and sensed vehicle speed to reduce the driver's steering effort. A yaw rate haptic torque is generated which is based upon vehicle rate error and is arranged to be added to the torque assist signal such that, when the yaw rate error builds up corresponding to increasing steering instability (e.g. understeer or oversteer) of the vehicle, the haptic torque added to the torque assist signal reduces the effective road reaction feedback sensed by the driver in advance of any actual vehicle stability loss whereby to allow the driver to correct appropriately in good time before terminal steering instability is reached. Alternatively, the haptic torque can be based upon vehicle lateral acceleration which is arranged to be subtracted from the torque assist signal such that when vehicle lateral acceleration builds up, corresponding to tighter cornering of the vehicle, the haptic torque subtracted from the torque assist signal increases the effective road reaction feedback sensed by the driver corresponding to the increase in cornering forces generated by the tyres of the vehicle.

Control-based reduction of pulsating torque for PMAC machines

Abstract: Control methods in torque pulsating reduction for surface-mounted permanent magnet motors are discussed in this paper. The pulsating torque is a consequence of the nonsinusoidal flux-density distribution caused by the interaction of the rotor's permanent magnets with the changing stator reluctance. The proposed control method is estimator based. To assure parameter convergence, Lyapunov's direct method is used in estimator design for the flux Fourier's coefficients. A novel nonlinear torque controller based on flux/torque estimate is introduced to reduce the influence of the flux harmonics. The influence of the cogging torque is considerably reduced at lower motor speed using the internal model principle and adaptive feedforward compensation technique. The overall control scheme and experimental results are also presented.

Non-Obstructive Particle Damping: New Experiences and Capabilities

Abstract: Non-Obstructive Particle Damping (NOPD) technology is a passive vibration damping approach whereby metallic or non-metallic particles in spherical or powder form, of heavy or light consistency, and even liquid particles are placed inside cavities or attached to structures by an appropriate means at strategic locations, to absorb vibration energy. Numerous laboratory experiments and applications on hardware have been carried out at PWR-CP. Test results are summarized in the following paragraphs to provide an overview of the technique and the effectiveness of particles as a means for damping vibrations as well as for acoustic attenuation. Specific applications and capabilities are presented regarding some of the major test/development programs undertaken during the past years at PWR-CP. Nomenclature b = inverse of the amplitude of the relaxation time, effective damping parameter 2 0 ω = natural frequency ζ = damping ratio x = displacement F = force t = time A = amplitude of motion m = mass ( = Average displaced power per cycle cyc W )

Engine torque calculation

Abstract: A torque calculator (10) and method for providing real time data that measures net torque output of a running engine (100) in a motor vehicle. Gross torque production (24) is calculated using engine speed and fueling data. Torque losses due to accessories, pumping, and friction (22, 26, 28, 30) are calculated and subtracted from gross torque production, and inertial torque is also accounted for to yield engine net running torque. The engine net running torque data and engine speed data are processed according to a filter algorithm (94) that compensates the engine net running torque data for engine speed. Transmission shifting (112) is controlled by the speed-compensated engine net running torque.

Drive control apparatus and method of alternating current motor

Abstract: A drive control apparatus and method drives an AC motor by applying a rectangular wave voltage thereto. The apparatus estimates the torque of a rotor of the AC motor, and detects a torque deviation which is the difference between the estimated torque and a required torque of the motor. A controller controls a state of the rectangular wave voltage applied to the AC motor, through torque feedback control based on the torque deviation, so that the torque approaches the torque command value. The controller detects a current rotation speed of the motor, and switches, in a predetermined order, a plurality of predetermined rectangular wave voltage states corresponding to different phase values of the rectangular wave voltage. The switching timing of the rectangular wave voltage states is set to a timing that deviates from a reference timing determined based on the current rotation speed, by a length of time corresponding to the torque deviation.

Apparatus and method of controlling a vehicle

Abstract: An apparatus and a method of controlling a vehicle is provided for correcting a lowered value of the torque of an output shaft in the gear shifting and suppressing a revolution speed of an input shaft on the basis of the lowered torque correction. The torque of the input shaft is adjusted at the termination of the gear shifting on the basis of the lowered torque correction.

Engine torque control for a hybrid electric vehicle using estimated engine torque

Abstract: A system and method for accurate control of engine torque for a parallel/series hybrid electric vehicle (PSHEV) is disclosed. An accurate estimate of engine torque is determined from the generator motor torque of a PSHEV. The estimated engine torque can then be used to control engine torque in a closed loop torque control strategy. The invention comprises at least one controller to receive, process and output torque signals; a first control strategy to determine a modified engine torque signal from at least a desired engine torque signal; and a second control strategy to determine variables for air, fuel and spark from said modified engine torque signal. The first control strategy can include a proportional integral (PI) controller. The estimated engine torque signal can be a function of an estimated generator motor torque signal, a generator motor speed signal and an engine torque loss signal.

Piston and rod assembly for air-actuated variable damping

Abstract: A damper includes a piston that carries a relatively compact control valve for controlling fluid flow through the piston. The control valve provides a variable amount of damping by regulating damper fluid flow between the extension chamber and the compression chamber of the damper during extension and compression strokes. Pressure regulation across the piston is controlled through a flow path as determined by the control valve. The damping force of the damper varies depending upon the loading conditions of the vehicle. The control valve is air pressure actuated to adjust the damping force and control the flow of fluid in the flow path.

Measurement of damping in structures by the power input method

Abstract: Damping refers to the extraction of mechanical energy from a vibrating system usually by conversion of this energy into heat. Damping serves to control the steady-state resonant response and to attenuate traveling waves in the structure. There are two types of damping: material damping and system damping. Material damping is the damping inherent in the material while system or structural damping includes the damping at the supports, boundaries, joints, interfaces, etc. in addition to material damping.

Method for particulate filter regeneration in vehicles having an automatically controlled transmission

Abstract: A system is described for minimizing engine torque disturbances that would otherwise cause degraded drive feel by a vehicle driver. The system utilizes multiple torque transmission paths of a transaxle unit mounted to the engine. The system manipulates the torque transmitted by adjusting the clutches of multiple torque transmission paths so that the torque disturbance in the engine results in relatively constant vehicle drive torque. In particular, during particulate filter regeneration, a potential torque increase is transmitted through multiple torque paths of the transmission to maintain output torque relatively constant.

Dual mode suspension damper controlled by magnetostrictive element

Abstract: Parallel paths for damping fluid are provided through the piston of a suspension damper, each of which are provided with separate damping valving sets to control damping. Communication through one of the paths is controlled by a movable control valve member, which is controlled by a magnetostrictive element which deforms in response to application of a magnetic field. The control valve member is moved between active and inactive positions in response to changes in a magnetic field applied by a coil mounted within the damper piston. In one position, all communication of damping fluid is through one of the damping valve sets, while in the other positon damping fluid communicates through both valve sets. Accordingly, damping levels may be varied by controlling the magnetic field.

Torque control strategy for management of regenerative braking of a wheeled vehicle whose powertrain includes a rotary electric machine

Abstract: A torque control strategy control for management of regenerative braking in a motor vehicle. A first processor ( 12 ) processes throttle request data ( 20 ) and torque modification data ( 40 ) from a second processor ( 14 ) to develop motor torque request data ( 28 ) for controlling rotary electric machine torque. The second processor processes brake request data ( 26 ), the throttle request data, and operating data from the at least one operating data source to develop friction brake torque data ( 30 ) for controlling friction brake torque applied to the vehicle and the torque modification data for the first processor. The two processors interact such that as long as the operating data from the at least one operating data source does not require that regenerative braking torque be limited, the torque modification data supplied to the first processor from the second processor equates to the brake torque request data, and the friction brake torque data does not cause the friction brakes to be applied, and when the operating data from the at least one operating data source calls for some limiting of the regenerative braking torque, the amount of limiting is subtracted from the torque modification data and the friction brake torque data equates to that amount of limiting for causing the friction brakes to be applied in that amount.