Showing papers on "Proportional control published in 1981"

Universal temperature control circuits

Abstract: Various electronic circuits are disclosed for controlling the temperature of an object by means of a resistive heating element. Some of the circuits include a digital display for displaying the actual temperature A plurality of different temperature sensors may be used, such, for example, as a resistive sensor, a thermocouple or a thermistor. The sensor may either have a positive or a negative temperature coefficient. Since most of the sensors are not strictly linear, different means are disclosed for compensating for their nonlinearity. Some of the control circuits feature a proportional control to which may be added an anticipatory control. Less sophisticated and more inexpensive circuits simply provide an on-off control.

Load voltage-current displacement regulator motor control system

Abstract: A three-phase motor control system (FIG. 1) having a current control regulator (CCR) that includes adjustable current ramp time or adjustable current level during starting and acceleration and incorporates a load voltage-current displacement regulator (VCFB) that automatically becomes effective when the motor approaches synchronous speed, thereby to reduce the power input to the motor to what is needed to run the load, thus saving energy. Additionally, a second quadrant detector (SQD) senses overhauling load conditions and operates a gate (NG) to lock out the load voltage-current displacement feedback signal thereby allowing the reference signal to place the motor across the line until the motor operation returns to the motoring quadrant. The system further includes means (24 in FIG. 2h) affording integral control and means (30 in FIG. 2h) affording proportional control of either the current control or the load voltage-current displacement control signal, with the gain of the proportional control being individually adjustable. The integral control is provided with high gain means (FET in FIG. 2h) that is rendered effective by a switch (TR in FIG. 2h) during current control and alternative low gain means (P4 in FIG. 2h) that is substituted during load voltage-current displacement control, the gain of the latter being individually adjustable.

A system for controlling a hydraulic cooling fan for an engine as a _function of ambient and coolant temperatures

Abstract: An automatic actuator system for a cooling fan of an internal combustion engine comprising a first detector for detecting the temperature of the cooling water in a cooling system for the engine and a second detector for detecting the atmospheric temperature. An electrical control circuit generates a first control signal corresponding to the cooling water temperature detected by the first detector and a second control signal corresponding to the maximum number of revolutions of the cooling fan as a function of atmospheric temperature detected by the second detector and generates an electrical output signal corresponding to the difference between the first and second control signals. A proportional control valve is coupled to the control circuit and controlled by the output signal of the control curcuit, and a cooling fan driving device is coupled to the control valve, wherein the rotational speed of the fan driving device is controlled as a function of the flow rate of fluid controlled by the proportional control valve.

Digital approaches to myoelectric state control of prostheses.

Abstract: The design of a new three-state myoelectric control system is presented. This controller determines its operating state from the initial rate of increase of the myoelectric signal, and the concept is realized in great measure through digital logic techniques. Proportional control of both active states (same dynamic range) is a unique feature of the controller. A microcomputer was interfaced in a simple way with myoelectric potentials to simulate the three-state controller described and to simulate various other state-determined control methods (some multifunctional). This was found to be a valuable method of evaluating control schemes without building the actual devices.

Feedback control of a single mass rotor on rigid supports

Abstract: This paper considers a single mass flexible rotor on rigid supports with proportional and derivative feedback control Undamped and damped free vibrations of the rotor-control system are considered as well as unbalance response Results indicate that proportional control alone increases the rotor critical speed, but does not affect the system damping Proportional control alone also decreases the system logarithmic decrement which tends to make the system more susceptible to external vibration excitations Derivative feedback control acts to increase the system damping, to reduce the response sensitivity, and is highly desirable

Controller for engine rotational frequency

Abstract: PURPOSE:To have a quick response to an unexpected fluctuation of load, by setting the lowering of engine rotation if any at the amount of control and then deciding the feedback as the control amount by the sum of the proportional control component, the integral control component and the basic control amount using the water temperature for the variable/constant. CONSTITUTION:When the measured rotational frequency N of an engine becomes less than the target rotation a frequency Nset, the deviation DELTAN is calculated by the subtractor 28. Then the Ipo memory table 29 is provided to the deviation DELTAN to store the 1st control signal Ipo. The proportional part is presumed according to the lowered amount of the frequency N and then stored in the memory table 22, and the 2nd control signal extracted out of the table 22 is reduced down to zero by the comparator 30 and as the time elapses. After a comparison 30, the engine is controlled by the 2nd control signal. Thus the lowered amount of rotation is set at the control amount, and the feedback is decided to the control amount from the sum of the proportional control component, the integral control component and the basic control amount using the temperature as the variable/constant. As a result, a quick response is secured to an unexpected fluctuation of load.

Fluid proportional control valve

Abstract: PURPOSE:To control a fluid proportional control valve surely, by detecting the temperature change of a permanent magnet of a valve material, which has the permanent magnet and an electromagnetic coil and is driven by changing the power supply quantity of the electromagnetic coil, to compensate the current value of the coil. CONSTITUTION:A fluid proportional control valve 21 consists of a fluid inlet 8, a fluid outlet 9, a valve seat 10, and a valve body 11, and a diaphragm 12 is provided in the upper part to keep the pressure in the side of the fluid outlet 9 constant against the pressure change in the side of the fluid inlet 8. Permanent magnets 13, a center pole 14, a top yoke 15, and a bottom yoke 16 constitute a magnetic circuit. An electromagnetic coil 18 is wound around a coil bobbine 17 in the magnetic gap. A temperature sensor 20 is fitted between or near permanent magnets 13 to drive a temperature compensating circuit 22. For example, a signal, which compensates the temperature change of the fluid proportional control valve 21 of a gas water heater, and the output signal of a water temperature detecting element 5, which is provided in the upper stream of a heat exchange 4, are inputted to an electric control circuit 6 to control the fluid proportional control valve 21, thus obtaining always hot water at a desired temperature.

Improvement of the dynamic characteristics in multiple-output dc-dc converter by using the magnetic coupling of the energy-storage reactor

Abstract: The dynamic cross regulation characteristics of the improved forward-type multiple-output converter is examined and compared with that of the conventional one. In the conventional forward-type multiple-output converter, the regulation performance of the cross regulated output voltages is deteriorated by the dynamic change of the load even when the proportional gain of the feedback controller is sufficiently large. On the other hand, in the improved converter, the dynamic cross regulation performance is ameliorated along with the increase in the proportional gain. Further, it can be improved more satisfactorily by using the appropriate P-D control. In this case, the magnetic coupling of the energy-storage reactor plays a key role in the dynamic cross regulation. That mechanism is clarified theoretically through the equivalent circuit models.

Display device for heat control

Abstract: PURPOSE:To enable the control which can be corrected at a glance safely and effectively by displaying the impossible control through the maximum or minimum ability of the heater CONSTITUTION:Gas passes through a proportional control valve 5 from the gas inlet 4, it is burnt in the burner 6 and heats up the heat exchanger 2 The proportional control valve 5 continuously controls the amount of gas in response to the current value flowing to electromagnetic coils The temperature sensor 7 provided at the outlet of the heat exchanger 2 and detecting the water supply temperature feeds the water temperature signal to the controller 8 incorporating the temperature control circuit The controller 8 outputs the driving signal to the proportional control valve 5 in proportion to the value of the temperature set knob 9 and the signal of the temperature sensor 7 The display device 11 displays the state of amount of load of gas to the maximum or minimum ability of the burner 6 With the constitution like this, the control which can be corrected at a glance and is safe and of good efficient, can be made, by displaying the disable control of gas with the maximum or minimum ability

Controller for hottwater supplying heater

Abstract: PURPOSE:To provide a controller for a hot-water supplying heater which has a single temeperature sensor and can set and control the heating temperature and the hot-water temperature independently of each other by enabling the switch for hot- water supply to regulate a proportional control valve under the hot-water supplying condition. CONSTITUTION:When the pilot flame has been lighted with the main fuel supplying valve 6 opened, turning on a heating switch 14, e.g., for heating operation, causes a proportional control circuit 16 to be energized as well as a switching circuit 24 so that a transistor Tr34 is turned on causing a resistor 25 for heating to be connected to a temperature sensor 15 in series. At the same time, a relay 18 actuates a circulating pump 20 to operate. In the control circuit 16, the detection signal obtained by the sensor 15 and resistors R35, 36 and 25 is inputted to an operational amplifier 45, where the deviation between said detection signal and the temperature set by resistors 37 and 38 is obtained and amplified in transistors Tr46 and 47 before being outputted to a proportional control valve 17 to perform temperature control.

Control unit for progressing and guiding continuous body in curved track in particular in continuous casting equipment

Abstract: PURPOSE:To compress the continuous body and prevent its surface cracking by letting the roller group far from the mold of the curved track be speed control reference rollers and the roller group close to the roll be compressive force control rollers at the compression casting CONSTITUTION:The electric motor 71 of a roller group 51 is run at the set speed of a speed reference setter 16 at the initial period of casting and the electric motor 72 of a roller group 52 is also controlled with the actual value of the electric motor 71 as a speed command Next, when the continuous body C reaches a roller group 30 and compression casting is started, the end of the continuous body C is detected by a tracking device 19 and the speed reference setter 16 controls the electric motors 71, 72, 73 Then, the current values of all the motors are input to a command control unit 17 which in turn changes over the proportional and proportional plus integral control action type speed controllers 91, 92 which had thus far made proportional plus integral control action to proportional control action, and transfer power controllers 141, 142 control the motors 71, 72 to let the other roller groups 51, 52 be compression control rollers, thereby acting compressive force upon the continuous body C On the other hand, the proportional plus integral control action type speed controller 93 of the motor 73 as the speed control reference roller of the roller group 30 on the lower stream side of the final curving point is maintained of a constant speed by the command value of the speed reference setter 16

Airrfuel ratio controlling device

Abstract: PURPOSE:To obtain the most suitable air-fuel ratio control at the time acceleration and slowing-down by a method wherein in the control circuit a differential circuit is provided, which differentiates the signals of the throttle valve opening extent of throttle sensor for putting out to a proportional circuit and an integration circuit. CONSTITUTION:Within a control circuit 21 consisting of an adder and the like, which add both output signals of a proportional control circuit 25 and an integration circuit 24, a differential circuit 28, which differentiates the opening extent signals of the throttle valve (not shown) of throttle sensor 20 to put out these to the proportional circuit 25 and the integration circuit 24. In case the throttle valve is operated to accelerate and slow down, the opening extent theta of the slottle valve fluctuates like A. The fluctuation of said opening extent theta is differentiated by putting in the circuit 28 only when it is fluctuated, the output of the circuit 28 makes the fluctuation as shown in B. Said differentiated output is conducted to the circuits 24 and 25 to increase the proportional and integration constants in each circuit 24 and 25. Thereby the convergence of the air-fuel ratio is raised to quickly converge on an logical air-fuel ratio even in the case of big fluctuation of an engine air-fuel ratio.

Driving apparatus of proportional magnetic valve

Abstract: PURPOSE:To eliminate the effect of the magnetic hysteresis onto the attraction force of a magnetic proportional valve due to material by driving the magnetic valve through controlling the ON-time in the same frequency of the pulse wave, in the proportional control valve which proportionally controls the flow rate of the fluid in a gas combustor. CONSTITUTION:The temperature of the flow rate which is detected in the detection part A is compared with the set value in the comparison part B, and the pulse signal having the width proportional to the magnitude of the flow rate which is determined by the difference described above is fed into a magnetic valve D from the pulse generating part E. The frequencies of the pulse waves for the flow rates l, (m), and (n) are equal, and the ON- time is different according to the magnitude of the flow rate. When a pulse wave is fed into a coil 1, the attractive force proportional to the average electric power is generated, and a movable core 2 stops at the position in balance with a spring 4, and the distance between a valve piece 3 and a valve seat 6 is adjusted, and the flow rate is controlled. Therefore, the effect of the magnetic hysteresis onto the attractive force of the proportional magnetic valve due to material can be eliminated.

Proportional control system for gas

Abstract: PURPOSE:To exercise proportional control over a flow rate of gas smoothly by a proportional gas control system which changes ranges of control current according to the kind of gas, by varying the control current for a solenoid from starting current to maximum energizing current while keeping the diameter of a valve constant. CONSTITUTION:To temperature setting part 11, temperature detection part 12, linear amplification part 13, control part 14, drive output part 15, feedback signal circuit 16, and proportional control valve 17, starting current setting part 18 and maximum energizing current setting part 19 are added. Then, setting part 18 applies a DC bias to a signal system as shown in fig. M to prevent the current flowing through valve 17 from decreasing below the starting current even if the signal level reaches ''0''. To setting part 19, a means of cutting the current at the level, equivalent to the maximum energizing current of a control signal level, for example, by a clipping circuit using a Zener diode is applicable. Then, while the diameter of a gas valve is kept constant, the control current for the solenoid is varied from the starting current to the maximum energizing current to exercise the proportional control over a flow rate of gas smoothly without reference to the kind of the gas.

Some new digital control schemes for three-phase zero-voltage switching

Abstract: Simple and economical digital schemes for burst control and direct digital proportional control for three-phase zero-voltage switching using single-phase sensing and CMOS digital ICs are explained. The schemes employ zero-voltage synchronous switching for both steady state operation and starting. The experimental results for a time base of 16 cycles for proportional type control with resistive loads are given, and they agree well with the theoretically predicted results. The circuits are expected to find extensive use in microprocessor-based power controllers.

Design And Implementation Of An Environmental Chamber Digital Control System

Abstract: This paper presents t he design and implementation (using a TI 9900 microcomputer system) of digital control systems for an environmental chamber utilized in the study of plant growth. Two control systems were implemented - one to control dry-bulb temperature and the o ther to control the carbon dioxide content in the chamber atmosphere. In addition, real-time data acquisition, automatic restart following power outages, and an interactive operating system have been achieved. The CO system is a closed-loop modified proportional control system. The closed-loop temperature control system uti1 ized a proportional-plusintegral-plus-de rivative digital controller. The environmental chamber is presently used in research by the USDA at Auburn University. 2

Controlling method for tension of rolled material at tandem rolling work

Abstract: PURPOSE:To prevent the overshoot at the tension control, by lowering the contribution of the integral control until the rolling mill's impact drop due to the feeding of the rolled material is recovered and the tension is settled to the specified value, at performing the titled control for the tension according to the proportional plus integral controlling method. CONSTITUTION:The deviation signal DELTAT, for the deviation of the output signal T of the detector 4 for the tension of the rolled material 3 between the i-th and (i+ 1)-th rolling mills 1, 2, from the reference tension signal T* given by the setter 5, is sent out from the subtracter 8. The contact 14 is inserted into the circuit; when the tip of the rolled material 3 is fed to the rolling mill 1 and next 2, the contacts 9, 13, are closed, and the tension control starts. At this time, since the contact 14 is left open, the tension control is performed by only the proportional controller 10. Next, at the point of time that the impact drop of the rolling mill 2, caused by feeding the rolled material's tip into the rolling mill 2, is recovered and the tension 3 is settled to the suitable value, the contact 14 is closed. Hereafter, the integral controller 11 is actuated for performing the tension control according to the proportional plus integral controlling method.

Gas combustion device

Abstract: PURPOSE:To minimize an ignition sound by throttling a gas proportional control valve with a pseudotemperature signal input to an electronic control part and providing a state of minor combustion at time of ignition. CONSTITUTION:A gas proportional control valve 5 is provided in a gas channel leading to a main burner 7. If a switch is put in ''ON'' position at time of ignition, a timer circuit 16 starts operating, causing a transistor Tr8 to be put in ''ON'' position during a timer setting time. A relay 17 sucks a contact point 17a, moving downward and adding a reference voltage split by resistances 18, 19 to a base for a transistor Tr1, throttling the gas proportional control valve 5. As a result, it is possible to minimize an ignition sound following a stage of minor combustion at time of ignition.

Energy Conservation and Proportional Control with Load Sensing Hydraulic Systems

Abstract: The demanding requirement of today's mobile equipment can be met by using load sensing hydraulic systems. They offer advantages of energy conservation as well as ease of obtaining proportional control. This paper presents the basic load sensing techniques, together with typical system configurations/characteristics. Their application to mobile aerial work platforms is discussed with emphasis on system stability and accuracy.

Compensating method for hydraulic servo system

Abstract: PURPOSE:To extend the frequency band width of a hydraulic cylinder to improve the control performance of the hydraulic servo system, by enhancing the natural frequency of the secondary delay element in the hydraulic servo system. CONSTITUTION:Pressure signal P of hydraulic cylinder 4 is detected by pressure detector 5, and the proportional output of proportional control meter 6 and the differentiation output of differential control meter 7 are added in addition point B3, and the diviation between the addition result and set value signal SV obtained through main control meter 1 is obtained in addition point B2 and is fed back to servo valve 3 connected directly to hydraulic cylinder 4 through servo-amplifier 2. By adjusting the differential constant of differential control meter 7 to an optimum value, the natural frequency of the secondary delay element in the operation characterisic of hydraulic cylinder 4 can be enhanced. By adjusting the porportional constant of proportional control meter 6, the damping coefficient in the operation characteristic of hydraulic cylinder 4 can be adjusted to an optimum value. Consequently, the frequency band of hydraulic cylinder 4 is extended.

Method of controlling electric power demand of indoor harmonic load and device for controlling operation of indoor harmonic load controlled by thermostat

Abstract: A method and apparatus for the control of power consumption in individual space-conditioning loads fed by an electric power network utilizes a commandable, programmable temperature control device which gradually, substantially continually changes the control setpoint in response to an external signal to reduce power consumption such that temperature changes go relatively unnoticed by the occupants. A radio receiver or the like is utilized to receive a signal from the power utility company and, in response to the signal, the setpoint function of the thermostat associated with the load becomes an electronically simulated function in accordance with the invention and the user-control setpoint is removed from the control loop. The effective load shedding is also greatly enhanced by the provision of an integral reset function in addition to the conventional proportional control within the temperature control system. The use of a plurality of such systems enables the power utility to control electric power network peak load with a minimum impact on the comfort of individuals in the conditioned spaces.