Motor Armature Research Articles

Cogging Force Verification at the Outlet Edge of the Armature of a Stationary Discontinuous Armature Permanent Magnet Linear Synchronous Motor

Cogging Force Verification at the Outlet Edge of the Armature of a Stationary Discontinuous Armature Permanent Magnet Linear Synchronous Motor

A method for estimating initial pole position of surface permanent magnet synchronous motors using pulse voltage

AbstractThe initial pole position must be estimated for speed sensorless vector control of PM motors. This paper presents a method to estimate initial pole position for Surface Permanent Magnet Synchronous Motors (SPMSM). For estimating the initial pole position, we utilize Fourier transformation for detecting the inductance change caused by rotor magnetic saliency. The six inductances, obtained by Fourier transformation of the voltage and current measured when a pulse voltage is applied to the motor armature winding respectively, will directly provide the exact information of pole position. The polar distinction is also carried out using Fourier transformation on the basis of the inductance change caused by magnetic saturation. Experimental results on a 0.3‐kW 8‐pole SPMSM demonstrate the validity of the proposed method. Although no machine was coupled with the tested motor, there was no change in rotor position during pole position estimation. In polar distinction, the maximum rotor position change was only 1.38 electric degrees. A method to estimate initial pole position without a motor voltage sensor is also discussed. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(1): 47–53, 2006; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/eej.20307

Stability Analysis of Phase Controlled Closed Loop DC Drive with Elastic Coupling Using D-Partition Technique

The analysis of a phase controlled closed loop dc drive is presented. The effect of an important mechanical factor, elasticity of coupling, on drive performance is analyzed. The D-partition technique is used to investigate the interaction of torsional stiffness of motor shaft, converter gain and armature time constant on the system stability. A design procedure to find the value of converter gain that gives minimum settling time is suggested.

Adaptive control of automotive electronic throttle

An electronic throttle is a DC servo drive which positions the throttle plate, thus providing drive-by-wire control of engine torque. This paper presents an electronic throttle control strategy consisting of a PID controller, and nonlinear friction and limp-home compensators. The emphasis is on the development of an adaptive control strategy, which is aimed to enhance the control strategy robustness with respect to process parameter variations, caused by production deviations, variations of external conditions, and aging. The adaptive strategy consists of auto-tuning and self-tuning algorithms. The auto-tuner provides automatic tuning of the control strategy parameters during vehicle assembly, or uses specific drive modes during normal use (e.g. each time the engine is turned off). The self-tuning algorithms are based on the permanent, on-line estimation of those process parameters which can vary within a single engine run (e.g. the DC motor armature resistance). The presented adaptive control strategy has been verified experimentally.

パルス電圧を用いた表面磁石同期モータの初期磁極位置推定法

The initial pole position must be estimated for speed sensorless vector control of PM motors. This paper presents a method to estimate initial pole position for Surface Permanent Magnet Synchronous Motors (SPMSM). For estimating the initial pole position, we utilize Fourier transformation for detecting the inductance change caused by rotor magnetic saliency. The six inductances, obtained by Fourier transformation of the voltage and current measured when a pulse voltage is applied to the motor armature winding respectively, will directly provide the exact information of pole position. The polar distinction is also carried out using Fourier transformation on the basis of the inductance change caused by magnetic saturation. Experimental results on a 0.3-kW 8-pole SPMSM demonstrate the validity of the proposed method. Although no machine was coupled with the tested motor, there was no change in rotor position during pole position estimation. In polar distinction, the maximum rotor position change was only 1.38 electric degrees. A method to estimate initial pole position without a motor voltage sensor is also discussed. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(1): 47–53, 2006; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/eej.20307

Simulation of Electrically Powered Hydraulic Steering System in Electric Vehicles

As concerns about global and local pollution have grown, stricter and stricter environmental legislations are enforced. A fuel cell city bus was developed in the last year, which is supported by Ministry of Science and Technology in China. The simulation of an electrically powered hydraulic steering system used in the developed fuel cell city bus is studied. The layout of the steering system is introduced. Resistive force of the steering tire originating from the vertical load and lateral force of tire is computed, and then the resistant force of hydraulic cylinder can be determined. The DC motor is used to drive the hydraulic vane pump and dynamic equation of the system is established. Simulation is performed with the help of Simulink of MATLAB. Relationships between hydraulic pressure and forward speed, voltage of armature of motor are simulated, respectively, which is helpful to determine parameters of hydraulic vane pump, DC motor in electrically powered hydraulic steering system in electric vehicles.

Mechatronic strategies for torque control of electric powered screwdrivers

The paper presents the results of a study on using mechatronics to enhance the performance and reliability of small electric powered screwdrivers (SEPS). A mechatronic solution to control the final tightening torque replacing the mechanical clutch of a purely electromechanical SEPS is presented. Torque estimation methods based on motor armature current measurements are integrated with an SEPS driven by a direct current motor. Strategies for controlling the final tightening torque of the screw fastening process are developed. The control strategies are tested in accordance with the ISO 5393 standard. It is shown that the mechatronic controller gives comparable performance to a SEPS with a mechanical clutch. The mechatronic solution has the advantage of reduced cost, size and complexity. The paper demonstrates the application of low-cost mechatronics in industrial power tools.

Steady-state and dynamic performance analysis of PV supplied DC motors fed from intermediate power converter

The steady-state and transient performance of PM and series motors coupled to centrifugal pump supplied from Photovoltaic source through intermediate buck-boost converter is analyzed. The effect of duty ratio selection based on maximum power operation of PV source and maximum daily gross mechanical power is investigated on the solar cell array operating point, motor armature voltage, armature current and motor efficiency variation. Studies are carried out by formulating the mathematical models for photovoltaic source, DC motors, power converter and load. Starting torque variation, Torque magnification factors expressions are derived and their variations plotted for the above two cases. Simulation software is developed for the transient and steady-state analysis of PV supplied DC motors for different duty ratios of power converter and solar insolations. Steady-state and transient performance characteristics are presented. The performance of PM DC motor is compared with the series motor operating under identical conditions.

Design and Analysis of Pulse-Width Modulated Closed-Loop DC Drive Torsional System Using Parameter Plane Technique

The design and analysis of a pulse width modulated closed-loop DC drive is presented. The effect of mechanical factors, like elasticity of coupling and periodic nature of load torque, on drive performance is analysed. The parameter plane technique' is used to investigate the interaction of torsional stiffness of motor shaft, amplifier gain and armature time constant on the system stability. A design procedure to find the value of amplifier gain to give minimum settling time is suggested. A comprehensive performance analysis of system designed is presented. Conditions leading to resonance are identified and measures to avoid it are discussed.

Mechanical drive control

Mechanical drives, for weapon platforms, comprising relatively long shafts with inertia discs, representing the motor armature, gearing, platform and load inertias, etc., are considered. Analysis procedures are employed to model a system which has driving and braking torque inputs. Two outputs arising from the motor armature angular changes and the load inertia position, which is to be regulated, are available. Procedures enabling the dominant oscillatory modes of the system to be influenced by proportional control are outlined. Performance enhancement using passive networks is employed, providing thereby further design flexibility. The responses of the system under open- and closed-loop conditions are computed. The simplicity of the approach which can also be applied to systems having an unequal number of inputs and outputs is commented upon.

Robust tracking control for constrained robots actuated by DC motors without velocity measurements

A dynamic feedback control design is proposed to treat the trajectory tracking control for constrained robots actuated by brushed DC motors. Only measurements of both angular motor position and motor armature current are required to construct the hybrid position/force control law. It is shown that for any preassigned attraction region all the variables of the closed-loop system are bounded and different robustness performance is achieved with respect to different uncertain signals. The attraction region can not only be arbitrarily enlarged but also explicitly constructed. Moreover, the proposed control algorithm can be employed directly to treat the tracking control of electrically driven unconstrained robots, and, consequently, both simple linear time-varying as well as linear time-invariant controllers are constructed. Finally, simulation examples are given to demonstrate the effectiveness of our proposed control algorithms.

Nonlinear quenching of current fluctuations in a self-exciting homopolar dynamo

Abstract. In the interpretation of geomagnetic polarity reversals with their highly variable frequency over geological time it is necessary, as with other irregularly fluctuating geophysical phenomena, to consider the relative importance of forced contributions associated with changing boundary conditions and of free contributions characteristic of the behaviour of nonlinear systems operating under fixed boundary conditions. New evidence -albeit indirect- in favour of the likely predominance of forced contributions is provided by the discovery reported here of the possibility of complete quenching by nonlineax effects of current fluctuations in a self-exciting homopolar dynamo with its single Faraday disk driven into rotation with angular speed y(τ) (where τ denotes time) by a steady applied couple. The armature of an electric motor connected in series with the coil of the dynamo is driven into rotation' with angular speed z(τ) by a torque xf (x) due to Lorentz forces associated with the electric current x(τ) in the system (just as certain parts of the spectrum of eddies within the liquid outer core are generated largely by Lorentz forces associated with currents generated by the self-exciting magnetohydrodynamic (MHD) geodynamo). The discovery is based on bifurcation analysis supported by computational studies of the following (mathematically novel) autonomous set of nonlinear ordinary differential equations: dx/dt = x(y - 1) - βzf(x), dy/dt = α(1 - x²) - κy, dz/dt = xf (x) -λz, where f (x) = 1 - ε + εσx, in cases when the dimensionless parameters (α, β, κ, λ, σ) are all positive and 0 ≤ ε ≤ 1. Within those regions of (α, β, κ, λ, σ) parameter space where the applied couple, as measured by α, is strong enough for persistent dynamo action (i.e. x ≠ 0) to occur at all, there are in general extensive regions where x(τ) exhibits large amplitude regular or irregular (chaotic) fluctuations. But these fluctuating régimes shrink in size as increases from zero, and they disappear altogether when ε = 1, leaving only steady régimes of dynamo action.

Scopolamine increases prehensile force during object manipulation by reducing palmar sweating and decreasing skin friction

The aim of this study was to determine whether relatively long-term changes in skin friction induced by a pharmacological blockade of sweat excretion would alter the grip forces applied to objects of a variety of different surface textures and frictions. Five men and three women were asked to lift the vertically mounted armature of a linear motor between the thumb and index finger and to hold it against an opposing force for 2 s. A 1.0-kHz tone indicated to the subject that the manipulandum had been correctly positioned between the upper and lower position limits. The linear motor generated a 2.5-N force tangential to the skin surface simulating an object weighing approximately 250 g. Three different polyamide plastic surfaces (either smooth or etched with 1.0 mm high Braille beads evenly spaced at 2- or 3-mm intervals) contacted the fingers in these experiments. Subjects lifted and held in a precision grip one of the three surfaces for blocks of ten consecutive trials, but the order of presentation of the three different textures was varied to offset the effect of expectancy. On a second block of ten trials the subjects were requested to release the object slowly to measure the ratio of the grip force normal to the grasped surface to the tangential load force at the moment of slip. This ratio or its inverse provided the coefficient of friction or the slip ratio for a particular subject and surface condition. Twelve hours prior to a second recording session all subjects placed transdermal patches of 1.5 mg scopolamine behind each ear to reduce palmar sweating by blocking the muscarinic receptors of exocrine sweat glands. The subjects were re-tested following procedures that were identical to the first session. Scopolamine significantly reduced the friction of the skin on the smooth and 2-mm beaded surfaces, but the friction of the 3-mm beaded texture was unaffected. Scopolamine also caused subjects to increase both the peak and static grip forces for all the textures including the 3-mm beaded surface, suggesting that for two of the three surfaces they were responding to the increased slipperiness of the skin due to reduced sweat production.

Performance evaluation of three-phase variable-speed DC drive systems with uniform PWM control

Pulse width modulation (PWM) control of DC drive systems is considered as a challenge to the conventional phase-controlled systems. In this paper, the performance characteristics of three-phase single-quadrant variable-speed DC motor drive systems with uniform PWM (UPWM) control are evaluated over the entire range of operation under the popular fan-type load characteristics. This includes the harmonic contents of the load and line currents. An experimentally verified mathematical model is used for this purpose. The solution procedure of the system is arranged for given loading conditions, which is highly necessary from the practical point of view. The impacts of the chopping frequency on the performance characteristics of the system, including the harmonic contents of the load and line currents, are thoroughly investigated and compared with those achieved by increasing the armature time-constant. It is shown that almost all the performance parameters of the load and line sides are improved as the chopping frequency increases. Also, the chopping frequency, when increased, is shown to have advantageous effects on both the amplitudes and the orders of the load and line harmonics. It reduces the amplitudes of the lower-order harmonics and simplifies the filtration requirements of the dominant higher-order harmonics. However, when the chopping frequency increases beyond a certain level, which can be considered as a function of the motor armature time-constant, it is shown that its influence becomes almost negligible and hence practically unjustified.

In situ measurement of motor electrical constants

SUMMARYMotor torque constant is an important parameter in modeling and controlling a robot axis. In practice this parameter can vary considerably from the manufacturer's specification, if available, and this makes it desirable to characterise individual motors. Traditional techniques require that the motor can be removed from the robot for testing, or that an elaborate technique involving weights and pulleys be employed. This paper describes a novel method for measuring the torque constant of robot servo motors in situ and is based on the equivalence of motor torque and back EMF constants. It requires a very simple experimental procedure, utilizes existing axis position sensors, and eliminates effects due to static friction and joint cross coupling. A straightforward extension to this approach can provide a measurement of motor armature impedance. Experimental results obtained for a Puma 560 are discussed and compared with other published results.

A superconducting linear motor drive for a positive displacement bellows pump for use in the g-2 cryogenics system

Forced two-phase cooling of indirectly cooled superconducting magnets requires circulation of liquid helium through the magnet cooling channel. A bellows helium pump is one possible way of providing helium flow to a magnet cooling system. Since the bellows type of helium pump is immersed in liquid helium, a superconducting linear motor drive appears to be an attractive option. This report describes a linear motor drive that employs oriented permanent magnet materials such as samarium-cobalt as the stator magnet system and a superconducting loudspeaker voice coil type of drive as the armature of the linear motor. This report examines drive motor requirements for a helium pump.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sensitivity model and synthesis of dead-beat algorithms in digital servosystems

The design of a sensitivity model of a digital servosystem with cascade control and dead-beat control algorithms is described. The problem of sensitivity model instability is discussed and a possible approach to obtaining a stable model proposed. An explicit relation was derived relating the changes of dead-beat control algorithm parameters to the absolute sensitivity functions of the measured output variable. The computer simulation results of parameter synthesis applied to the dead-beat dc motor armature current and angular speed control algorithms indicate that the tuning of control algorithm parameters is completed after a single iteration for smaller changes of drive parameters, while two or more iterations are required in case of large changes of drive parameters. The developed method for synthesis of time optimal controller parameters could be suitable for adaptive control with self-tuning of control algorithm parameters.

Development of a Digitally-Controlled Servo Amplifier for Robots

Kawasaki Heavy Industries, Ltd. has developed a digitally-controlled servo amplifier for robot servo motors. The motor's armature current, position and velocity are controlled by the software in a digital signal processor. The servo is designed for high reliability, performance, flexibility and compactness. To achieve these objectives, we developed an ASIC which controls PWM signals for power transistors and encoder signals. The servo amplifier is currently used in the new Kawasaki AD series of robot controllers.

Robust tracking control of rigid-link electrically-driven robots

A robust tracking controller for rigid-link electrically driven (RLED) robot manipulators operating in free-space or under motion constraints is introduced. Using models of the robot dynamics and environmental constraints, a dynamic model with decoupled position and force degrees of freedom is obtained for the mechanical subsystem with respect to a set of task-space coordinates. A robust tracking control is then formulated for the decoupled manipulator dynamics and the electrical actuator dynamics, which yields a global uniform ultimate bounded (GUUB) stability result for the position and velocity tracking error. The controller is robust with respect to parametric uncertainties and additive bounded disturbances in the RLED dynamic model. The controller requires measurement of the robot link positions, link velocities, and motor armature currents.

A microcomputer-controlled thyristor bridge rectifier experiment for undergraduate electric machinery laboratory

This paper describes the design and implementation of a 5 kW microcomputer-controlled thyristor bridge rectifier (TBR) that has been introduced in the undergraduate electric machinery laboratory at Montana State University. The unit is used in an independent experiment on the operation of the TBR and its control by a microcomputer, as well as for controlling the applied voltage to the armature of a DC motor for controlling its speed. Since the operation of the motor speed controller is based on control of the TBR, it was noticed that the addition of the TBR experiment will help students better understand its operation as well as the operation of the DC motor speed controller experiment. Experimental results are presented on the operation of the rectifier, and evaluation of the experiment is reported. >