Showing papers on "Proportional control published in 1982"

Application of an Adaptive Pole-Zero Placement Controller to Chemical Processes with Variable Dead Time

Abstract: An algorithm for providing adaptive control and dead time compensation of single input-single output systems with unknown or varying dead time is presented. The algorithm is designed by pole-zero placement and is unique in that an explicit estimate of the dead time is not required, thus avoiding a difficult estimation problem. Parameter estimation for the adaptive controller/dead time compensator is performed with a recursive least squares algorithm. Simulation studies and experimental application on a heat exchange loop on a pilot scale distillation column verify the performance of the algorithm. In each example, the performance of the adaptive controller/dead time compensator is compared to that of a proportional plus integral controller, illustrating the improvement in performance obtainable with the adaptive algortihm.

Bang-bang dual-mode integral controller with proportional control output useful for temperature control

Abstract: Control system which measures overshoot or undershoot time of a controlled variable with respect to a set value and adjusts a proportional count if the overshoot or undershoot time period exceeds fixed values. The proportional count is used to control the system output in a proportional manner, such as supplying k out of every n cycles of power, where k represents the proportional count. To prevent excessively long periods of overshoot or undershoot, an overlimit detector provides adjustments of the proportional count when the overshoot or undershoot measured time exceeds an overlimit value. The control system has general applicability but is described in the temperature control of a fuser hot roll such as used in electrophotostatic copiers.

A Variable Structure Approach to Robust Control of VTOL Aircraft

Abstract: This paper examines the application of variable structure control theory to the design of a flight control system for the AV-8A Harrier in a hover mode The objective in variable structure design is to confine the motion to a subspace of the total state space The motion in this subspace is insensitive to system parameter variations and external disturbances that lie in the range space of the control A switching type of control law results from the design procedure The control system was designed to track a vector velocity command defined in the body frame For comparison purposes, a proportional controller was designed using optimal linear regulator theory Both control designs were first evaluated for transient response performance using a linearized model, then a nonlinear simulation study of a hovering approach to landing was conducted Wind turbulence was modeled using a 1052 destroyer class air wake model

Dynamic Analysis of Power Systems with Multiterminal HVDC Links and Static Compensators

Abstract: The paper presents a generalized small signal model of a multinode power system having multiterminal HVDC links and thyristor controlled static compensators This model is suitable for the application of modal control techniques for centralized dc power modulation to improve the dynamic stability of the ac-dc system. For practical implementation of the centralized controlller, proportional-plus derivative feedback of the output states has been used to shift the dominant modes to prescribed locations. Further, a decentralized control scheme based on the control of the static compensator alone and a combination of both static compensator and dc power modulation have been presented in this paper to bring out the differences between the two approaches. An eigenvalue search has been used to optimize the controller gains. Simulation results for a 3-terminal system are presented to highlight the important features of both the modal control and dc power modulation along with reactive power control schemes.

Optimum Setting for Proportional Controller

Abstract: On the basis of four common criteria?integral square error (ISE), integral absolute error (IAE), time integral-square-error (ITSE), and time integral absolute error (ITAE)?optimal lines for typical sampled data servo drives for computer numerical control (CNC) are derived and approximated by simple equations. The objective is to provide the control engineer with a simple equation for the selection of the control parameters. A line of critical damping is also derived and simply approximated.

Digital flight control system design using singular perturbation methods

Abstract: In this paper a longitudinal output feedback tracker is developed for an aircraft and is shown to produce excellent performance for three different flight conditions without change of the control law matrices. The aircraft utilizes flight propulsion control coupling to provide greater control and responsiveness to command inputs. The singular perturbation method is applied to obtain an output-feedback digital multivariable control. Each flight condition has three command modes: positive pitch pointing, vertical translation, and straight climb. Decoupling of the outputs is demonstrated. A sensitivity study is performed to validate the robustness of the design and to illustrate design parameter influences on system response. The paper contains a summary of the control law design method. Since the CB matrix of the aircraft model does not have full rank, the use of a modified output feedback is used to obtain the required tracking performance.

Condition control system for heat transfer

Abstract: A condition control system for e. g. a boiler is responsive to a pressure (or temperature) signal PR to generate an on/off firing signal 22 and a firing rate signal 26, by a proportional control path (via 50) and an on/off path (51). The system operates in 2 modes: proportional (modulating), and cycling, determined by a limit switch signal LS. To minimize the cycling rate when cycling, the system is forced into the lowest fire rate when first fired up; the rate of change of pressure is sensed (at 86) and the signal LS changes the mode to proportional if the pressure falls (indicating that the low fire rate is inadequate). In the proportional mode, integral action (via 57) is used to adjustthe setpoint PSET (via 44) to reach a stable operating state. In the cycling mode, the setpoint PSET is adjusted in dependence on the duty ratio of the cycles.

Electronic air-fuel ratio feedback controller for internal combustion engine

Abstract: PURPOSE:In an air-fuel ratio fedback control utilizing the exhaust gas density, to perform the accurate and quick control by comparing the output from O2 sensor with the referential level then performing the integration control with the rotation for every predetermined time of the angular positional signal. CONSTITUTION:The proportional control or the integration control is performed selectively in accordance to the variation of the output voltage from an O2 sensor 15 under the closed loop control. In other word when the output voltage from the O2 sensor 15 will vary only at the high or the low level side for the referential voltage, such integration control is performed as the O2 feedback factor KO2 will be increased/decreased with the time constant corresponding to the one rotation Ne of the engine, while when the output voltage from the O2 sensor 15 will vary from the high to the low or from the low to the high for the referential voltage, such proportional control is performed as the value corresponding to the rotation is temporality increased/decreased against the factor KO2. Consequently the accurate and quick control corresponding to the rotation is achieved resulting in the stabilization of the operating performance and the exhaust gas emission.

Method and equipment for controlling steam temperature in thermal power plant

Abstract: PURPOSE:To provide control for smaller variation in steam temperature by lessening the response delay of a mill through a technique with which the quantity of pulverized coal at a burner inlet can be precisely detected by incorporating a coal mill model into a control system CONSTITUTION:Parameters such as a mill differential pressure 110, a primary air differential pressure 111 and a coal feed command signal 109 are entered as the feedback amount of a corrected fuel request command signal which is the sum of a fuel request signal 107 and a temperature master signal 106 The quantity of a pulverized coal at a burner inlet 105, the optimum setpoint of a proportional gain 103 and the optimum setpoint of a reset time 104 are outputted by performing operation using a coal mill dynamic characteristic model 202 according to a momentum conservation law and a mass conservation law

Effect of Cascade Control on Loop Performance

Abstract: Plots are presented and equations are developed to estimate the improvement in control loop performance by the use of cascade control on various types of processes. The data were generated by a dynamic simulation program. Guidelines are also presented for the implementation of cascade control.

Dynamic performance of a discharge air-temperature system with a p-1 controller

Abstract: The dynamic performance of a discharge air control system with a proportional or proportional plus integral controller is modeled and analyzed. The model includes a sensor, controller, actuator/valve, and heating coil. System performance is analyzed as a function of parameters which include proportional gain, integral gain, actuator with and without positioner, and with constant and variable valve-coil gain.

Controlling method for stoppage of servomotor and its control circuit

Abstract: PURPOSE:To minimize an error of a static position of the motor remarkably by increasing a proportional gain of the stoppage control circuit to a high gain just after modes transfer to a stoppage controlling mode from a speed controlling mode and changing over the proportional gain to a low gain after a fixed time passes. CONSTITUTION:In the speed controlling mode, an analog switch ASW1 is at off and an ASW2 is at on, and speed control signals S11 from a speed control circuit are inputted to an operational amplifier OP-AMP of a head amplifier 3. When the modes are changed over to the stoppage controlling mode, changeover control signals S92 from a processor change to a level L from a level H, and the switch ASW2 is at off and the ASW1 is at on while changeover control signals S91 are given at the level L, thus keeping a switch ASW3 under an on condition, then increasing the proportional gain to a comparatively large value. Since the signals S91 change to the level H after a fixed time passes after a point of time when the modes transfer to the stoppage controlling mode, the switch ASW3 is at off, and the proportional gain is minimized more than that just after transfer.

Microprocessor control system for 200-kilowatt Mod-OA wind turbines

Abstract: The microprocessor system and program used to control the operation of the 200-kW Mod-OA wind turbines is described. The system is programmed to begin startup and shutdown sequences automatically and to control yaw motion. Rotor speed and power output are controlled with integral and proportional control of the blade pitch angle. Included in the report are a description of the hardware and a discussion of the software programming technique. A listing of the PL/M software program is given.

Control circuit for combustion equipment

Abstract: PURPOSE:To realize the slow ignition operation by a method wherein a capacitor with large capacity is connected in series with the temperature sensing element of a proportional control circuit to control the temperature so as to operate a proportioning valve by integral action with the elapse of a certain time after the ignition of minimum gas flow for pilow flame. CONSTITUTION:When an ignition switch 32 is closed, the resistance of the temperature sensing element 30 is initially shorted due to the capacitor 31 connected in series with the element 30, resulting in bringing the base voltage of a transistor 11 to zero and in turning a transistor 6 OFF to keep the proportioning valve 5 in the closed state. Meanwhile, with the charging of the capacitor 31, the transistor 11 is turned OFF and the transistor 6 is turned ON, resulting in opening the proportioning valve to ignite a main burner by the polot flame kept burning with the minimum gas flow.

Modeling and analysis of AC/DC converter system with digital PI controller

Abstract: A digitally controlled AC/DC converter system with a current control loop, based on a single-phase half-controlled thyristor bridge is presented. Three type proportional plus integral (PI) controller is described. When a digital PI controller is employed, in which the integral term is replaced by the summation one, the control system becomes a multirate sampled-data system having two different sampling rate. This paper gives the modeling and analysis procedures on the digitally controlled system including a multirate sampled-data system. For this control scheme, a microprocessor is used to implement the feed-back control and calculates the firing angle in real-time.

Flow rate controller

Abstract: PURPOSE:To attain a proper control of flow rate to an input by giving a numerical control to the actions of an object to be controlled to an input signal which varies by the environment of application, the proper characteristics of the object to be controlled itself and other conditions. CONSTITUTION:For instance, the signal supplied from a detector S for an air cooling load is received by a controller C1 to set an opening amount of the 1st control valve V1. The signal of the detector S is received by a controller C2 incorporating a voltage type balancing relay 2, etc. via the valve V1. Then the opening amount of the 2nd control valve V2 is set for example opposite to the room cooling load. The relay 2 incorporates an unbalance detecting element A. A bridge circuit B is constituted with the element A, an input side potentiometer 1, an output feedback potentiometer 3 and an auxiliary potentiometer 4. As shown in a chart 1, the opening amount of the valve V2 is controlled properly so as to prevent the excessive burning during a partial load in comparison with a conventional proportional control valve.