Constant Speed Control Research Articles

Control issues in adjustable speed drives

Adjustable-speed electric motor/generator drives (ASDs) are used to save electric energy and increase productivity in variable-output work processes of all new and well-established industries such as: digital information gadgets, digital home appliances, automotive and robotics electric actuators, pump compressors, other vehicles, industrial processes, and distributed and renewable energy system electric generators. With power levels that go from less than 1 W to hundreds of megawatts, ASDs have become in the last 20 years a very dynamic worldwide industry/market. The recent advances in electric/magnetic materials, modeling tools, design and fabrication of electric machines for ASDs, corroborated with matched progress in ASD power electronics with power quality control, DSP menu based control, novel sensors and interfacing, field orientation and direct torque control (FOC and DTC), and advanced state observers for motion or current sensorless control, has prompted us to do this selective review. This article selects a few control issues in ASD, such as performance indices, three-phase ac motor control principles, wide constant power speed control, motion-sensorless control of ac drives, variable-speed ac generator control, and linear motor drives control, and discusses their basics, recent progress, and a few directions of ASD research and industrial development for the near future.

An Adaptive Optimal Control Design for a Bolus Chasing Computed Tomography Angiography

To improve imaging quality and to reduce contrast dose and radiation exposure, an optimal adaptive bolus chasing controller is proposed and tested based on actual patient data. The controller estimates and predicts the unknown 2D bolus density online and then determines the optimal control actions. Tracking errors are mathematically quantified in terms of estimation errors. The test results not only support the analytical analysis and exhibit its superior performance over the current constant-speed controller, but also demonstrate the clinical feasibility.

Development of a robot control method for curved seal extrusion for high productivity in an advanced Toyota production system

Recent Japanese enterprises have been promoting global production to realize uniform quality worldwide and production at optimal locations for survival amid severe competition. The authors considered the necessity of including the above method in the strategic application of the Toyota production system (TPS), and clarified Advanced TPS as the global production by manufacturing technology. In the future, reformation of the production workshops transformed by robotics and IT will be necessary in order to keep the same quality worldwide and production at optimum locations. Thus manufacturing technology had to be improved for mass production by developing the latest robot control methods. So far, the authors have established a robot control method for global production called RCM-EPC. RCM-EPC contains a three-core robot control method with (i) locus and speed control of the external point (-LSC), (ii) simulation for optimizing the operation position (-SOP) and (iii) constant speed control for robot movement (-CSC). Furthermore robots are applied to several applications in order to improve productivity and achieve a high-quality appearance. In particular, the authors here introduce an up-to-date glass-integrated curved seal extrusion (CSE), which is a new technology for use in manufacturing: the automobile-window mole as an example for Toyota – one of the most advanced automotive manufacturing enterprises in the world. With the demonstration of a 50% reduction in manufacturing costs using Advanced TPS, the authors have achieved high productivity and quality assurance in global production.

마이크로터빈의 새로운 점화 기법과 점화 인식 로직 개발

This paper presents new ignition method and ignition recognition logic for a microturbine. New ignition method is designed by constant speed control of a microturbine with pre-determined time during a ignition period. It make more accurate air-fuel ratio as well as give enough time to ignition system to have full performance under cold temperature. And ignition recognition logic is designed by observing output current change of inverter by generating output torque of a microturbine in the instant of ignition. For filtering a output torque current of inverter with high frequency, we applied a moving average method. So far, ignition recognition is usually implemented by measuring of exhausted gas temperature(EGT) of microturbine. The proposed logic can give more accurate judgement of ignition as well as keep a good working of starting system under out of order a temperature measuring system and biased initial value of EGT sensor. Finally, the two proposed logics are proved by field operating a microturbine under various conditions.

An Experimental Investigation of Fuzzy Logic Speed Control in Permanent Magnet Synchronous Motor Drives

One possible application of artificial intelligence in motion control is the use of a fuzzy logic (FL) speed controller. Regardless of all the work, it appears that a detailed investigation of the drive behaviour under FL speed control, using an experimental rig, is still missing. This paper provides an in-depth report on operation of a vector controlled permanent magnet synchronous motor subjected to FL speed control. The transients studied include speed response to large step speed command from standstill with nominal inertia and with an increased inertia, response to small step speed reference change with nominal inertia and with an increased inertia, and response to step load torque application. The transient behaviour is examined for various initial speed settings, so that an insight into the impact of the operating point on the controller behaviour is enabled. It is shown that the reference speed at which certain transient is initiated may strongly influence the speed response obtainable with constant parameter FL speed controller.

Mathematical modelling of supermarket refrigeration systems for design, energy prediction and control

This paper describes a mathematical model developed to simulate the performance of supermarket refrigeration systems. Such a model can be used for the comparison of different systems and control strategies in terms of their energy and total equivalent warming impact. The model is based on a large number of component models which have been linked together within the TRNSYS environment. Major component models include the compressor, air-cooled condenser, thermostatic expansion valve, display cabinet and control. The overall system model has been validated against monitored data obtained from both a laboratory-based system and a full-scale system in a supermarket in Scotland. The value of the model is illustrated by determining and comparing the effectiveness of head pressure and variable-speed control against fixed head pressure and constant speed control. It is shown that even at summer ambient conditions the system can be operated without problems at much lower head pressures than is done in practice under fixed-pressure control strategies. The use of variable-speed control on one of the compressors can also provide better control of the suction pressure and a substantial (up to 23 per cent) energy savings compared to on-off control.

Robust Speed Control of Ultrasonic Motor Based on H.INF. Control with Repetitive Compensator.

A constant speed control system of an ultrasonic motor(USM)is designed based on H∞ control with a repetitive compensator. Generally driving mechanism of USM uses frictional force. It comes the following disadvantages of the motors : (1)the dynamic response shows non-linear natures and depends on the operating temperature ; (2)the average rotational speed gradually decreases with temperature rise ; (3)the speed fluctuates periodically synchronizing with rotation. To tackle the problems, multiplicative uncertainties are introduced into the plant model to represent the non-linearity and the temperature dependency. The decrease and the fluctuation in speed are treated as a step and a periodic disturbance respectively. The control system is designed as follows. Firstly, and integral type H∞ controller is designed which guarantees robust stability against the uncertainties. Secondly, a repetitive compensator is attached to the system without loosing stability to attenuate the periodic disturbance. Experiments confirm the validity of the proposed control system.

Robust Speed Control of Ultrasonic Motor based on H.INF. Control with Repetitive Compensator.

A constant speed control system of an ultrasonic motor (USM) is designed based on H∞ control with a repetitive compensator. In spite of the excellent features, USM has the following problems because of the driving mechanism using frictional force: (1) the dynamic response is non-linear and depends on the temperature. (2) the averaged rotational speed gradually decreases as the temperature rises. (3) the speed fluctuates periodically depending on the rotational angle. In this study, the input and output of the USM are driving frequency and rotational speed respectively. The multiplicative uncertainty is introduced into the plant model to represent the non-linearity and the dependency on the temperature. The decreasing and fluctuating speed are considered as a step and a periodical speed disturbance respectively. The control system is designed as follows: Firstly, an integral type H∞ controller is designed which guarantees robust stability against the uncertainty. Secondly, a repetitive compensator is attached to the system without loosing stability to attenuate the periodical disturbance. Experiments confirms the validity of the proposed control system.

Constant Speed Control of the Quick Return Mechanism Driven by a DC Motor.

For the dynamic analysis, Hamilton's principle and Lagrange multiplier method are applied to formulate the equations of the motion of a quick return mechanism driven by a DC motor. The coordinate partitioning theorem is applied here to provide a theoretical reduction of differential-algebraic equations to differential equation form. In this work, we are concerned with the analysis and design a modified proportional-integral-derivative(PID)controller which was based on the principles of conventional PID controller to keep the driving crank with a constant angular velocity. Results of numerical simulations show that the angular velocity fluctuation can be reduced substantially and this modified PID controller also can give reasonably good results whatever it have or not considered cutting force in the system.

Constant Speed-Control of a Series Universal Motor.

Constant Speed-Control of a Series Universal Motor.

Constant speed control of a motor driven mechanism system

One of the basic assumptions in both the synthesis and analysis of many four-bar mechanisms is that the angular velocity of the input crank is constant. However, this assumption may not be valid when an electric motor is connected to drive the mechanism. In this study, the motor-mechanism combination is treated as a single system, and control strategies are developed to efficiently reduce the crank angular speed fluctuation of a four-bar linkage. A complete mathematical model for the controller-motor-mechanism is developed, using a state space representation. Based on the principles of conventional PID control and the information obtained from steady state constant speed analyses, several modified PID type control strategies are developed. Nonlinear programming techniques are utilized for the determination of optimal controller gains. Numerical simulations show that, by using feedback control, the crank speed fluctuation can be reduced substantially.

High Precision Control for Electrical Machine with Periodical Disturbances based on Optimal Repetitive Control.

It is well known that the speed control system, even though which is constructed with an excellent control method, has an unexpected steady speed error when it is suffered by a periodical load disturbance. As the method of eliminating the speed fluctuation caused by such kind of disturbance, a repetitive control is the most effective. But the repetitive control method is only adoptive for a constant speed control system.In this paper, a novel control system designing method which is effective to both the constant speed control system and variable speed driving system is shown. The fact that a periodical disturbance depends on time function and also rotational angle is utilized to design the control system. From the result, the numerical modeling of the controlled object is derived in the rotational angle function domain. For the obtained numerical model, an extended state variable equation based on the original system is presented by using the control technique named “Error System Technique”. And then the optimal feedback gains are decided by solving the optimal regulator problem for the extended state equation. Therefore, a stability of the system is ensured.The proposed control method is applied to DC motor variable speed control system and the experimental setup is constructed. Finally, the effectiveness of the proposed method is confirmed by the result of simulations and experiments.

Studies on High Performance Generation System of Micro-hydraulic Turbine in Low Flow Rate and Lew Head.

Improvement of the generation power in micro-hydraulic turbines is shown in the range of low flow rate and low head using a new inverter generation system. The generation power can be obtained down to very low flow rate and head using the new inverter generation system with variable rotational speed control, where a water turbine connot produce the electric power in a normal constant-speed-control system. Experiments were carried out using a practical micro-hydraulic turbine with 2 kW output and variable rotational speed in a forest on the mountain, Mie University. The total efficiency is kept at a high value even in the very low partial load area. Compared with the constant speed control, the generation power is improved over 20 percent by varying the rotational speed.

Steady-State Performance Evaluation of Saturated Field Oriened Induction Motors

Steady-state performance characteristics of the stator field oriented control, air-gap field oriented control and rotor field oriented control induction motor drives are compared. Effects of the magnetizing flux saturation on the magnetizing inductance and conductor temperature on the rotor resistance are rigorously included in the performance equations. Key performance indices, such as relative flux level, torque, motor efficiency, and input power factor, are compared when the drive is operating under constant torque and constant speed control. >

Realization of time-optimal single-step velocity response control of field-oriented induction machines under the condition of nonsaturation of flux

A time-optimal single-step velocity-response control scheme for field-oriented induction machines is implemented, based on the analytical solutions of the time-optimal control problem in the case of nonsaturation of flux. High-velocity response is achieved despite field-weakening for low acoustic noise or high-efficiency drives. The optimal control under the operation conditions of start-up, acceleration/deceleration, and constant speed control against impact load is considered and approximate control methods are derived to simplify the control algorithm. The scheme is realized by only adding the look-up tables of the optimal control laws to the conventional indirect field-oriented control system. Feasibility of the control scheme is verified by simulations and experiments, which show fast and smooth velocity response. Furthermore, comparison with other control methods indicates that the time-optimal control scheme is very advantageous, especially when the mechanical response time is comparable to the electrical rotor time constant and/or when the rated flux is high. >

CRTを利用したCPPコントロールバックアップシステム

This paper reports on a CPP Control Back-up System utilizing a CRT, which has been newly developed by NKK and installed on the NKK's new energy saving ships equipped with PC engines and controllable pitch propellers (CPP) .This system consists of a CPP control system featuring automatic load control, constant ship speed control and constant SHP control as well as a data display system utilizing a color graphic CRT which displays the characteristics of the main engine and the CPP, the operating point of the main engine and various actual operating data of the main propulsion system.This system makes it easy to perform fine aiming of such operation targets as energy savings, high operating rates, low maintenance costs, etc.

Minor-Closed-Loop Control of a Single Stack Variable Reluctance Stepping Motor for High Speed Positionning

This paper presents a viable minor-closed-loop control system for a typical stepping motor. Maximization of the stepping motor's average output torque is achieved by control of the switching angle in a high resolution discrete manner. This approximates an experimentally determined optimum relationship between switching angle and maximum average output torque. The control function is identical during acceleration and deceleration and the control scheme is therefore suited to high speed positioning applications. A simple form of constant speed control is provided without resorting to the use of switching angle manipulation. The switching angle relationship is stored in read-only memories as a look-up table and is keyed to the motor speed through a feedback pulse period measurement. The switching angle is optimized in real time in response to overall system requirements. A load-independent control scheme is thus obtained. By storing the switching angle data in reprogrammable read-only memories, stepping motors of similar design philosophy having different performance characteristics can be accommodated by simply reprogramming these memories. One control system can thus be used for a large number of stepping motors.

Electron trapping noise in SOS MOS field-effect transistors operated in the linear region : S. T. Hsu. RCA Rev.38, 226 (June 1977)

This paper presents a viable minor-closed-loop control system for a typical stepping motor. Maximization of the stepping motor's average output torque is achieved by control of the switching angle in a high resolution discrete manner. This approximates an experimentally determined optimum relationship between switching angle and maximum average output torque. The control function is identical during acceleration and deceleration and the control scheme is therefore suited to high speed positioning applications. A simple form of constant speed control is provided without resorting to the use of switching angle manipulation.The switching angle relationship is stored in read-only memories as a look-up table and is keyed to the motor speed through a feedback pulse period measurement. The switching angle is optimized in real time in response to overall system requirements. A load-independent control scheme is thus obtained.By storing the switching angle data in reprogrammable read-only memories, stepping motors of similar design philosophy having different performance characteristics can be accommodated by simply reprogramming these memories. One control system can thus be used for a large number of stepping motors.

Ionizing radiation effects on NMOS microprocessors : David K. Myers. Proc. Electron. Components Conf., Arlington, Va. (May 16–18 1977). p. 521

This paper presents a viable minor-closed-loop control system for a typical stepping motor. Maximization of the stepping motor's average output torque is achieved by control of the switching angle in a high resolution discrete manner. This approximates an experimentally determined optimum relationship between switching angle and maximum average output torque. The control function is identical during acceleration and deceleration and the control scheme is therefore suited to high speed positioning applications. A simple form of constant speed control is provided without resorting to the use of switching angle manipulation.The switching angle relationship is stored in read-only memories as a look-up table and is keyed to the motor speed through a feedback pulse period measurement. The switching angle is optimized in real time in response to overall system requirements. A load-independent control scheme is thus obtained.By storing the switching angle data in reprogrammable read-only memories, stepping motors of similar design philosophy having different performance characteristics can be accommodated by simply reprogramming these memories. One control system can thus be used for a large number of stepping motors.

Liquid crystal technique for field detection in microwave integrated circuitry : F. Giannini, P. Maltese and R. Sorrentino. Alta Frequenza p. 170 (April 1977)

This paper presents a viable minor-closed-loop control system for a typical stepping motor. Maximization of the stepping motor's average output torque is achieved by control of the switching angle in a high resolution discrete manner. This approximates an experimentally determined optimum relationship between switching angle and maximum average output torque. The control function is identical during acceleration and deceleration and the control scheme is therefore suited to high speed positioning applications. A simple form of constant speed control is provided without resorting to the use of switching angle manipulation.The switching angle relationship is stored in read-only memories as a look-up table and is keyed to the motor speed through a feedback pulse period measurement. The switching angle is optimized in real time in response to overall system requirements. A load-independent control scheme is thus obtained.By storing the switching angle data in reprogrammable read-only memories, stepping motors of similar design philosophy having different performance characteristics can be accommodated by simply reprogramming these memories. One control system can thus be used for a large number of stepping motors.