JPH011001A - Servo motor control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a control device for a servo motor that energizes a mixing valve etc. that adjusts the mixing ratio of hot water and water, and in particular, it is capable of preventing hunting of the servo motor. In addition, it is possible to prevent the servo motor from malfunctioning due to variations in the operating dead zone of the servo motor, and to control the servo motor with the minimum operating pulse width. Servo motor control devices using servo motors are widely used for controlling mixing valves, water flow control valves, etc. of mixing parts, positioning devices using potentiometers, and the like. For example, in a servo motor control device that drives a hot water mixing valve of a water heater, the servo motor drive circuit is operated with a constant pulse width until the mixed water temperature, which is the controlled variable, matches the set water temperature, which is the control target value. Alternatively, control is performed to match the mixed hot water temperature to the set hot water temperature by supplying a control pulse having a pulse width that gradually becomes smaller as the controlled amount approaches the control target value.

(Problem to be Solved by the Invention) However, in conventional servo motor control devices that control using pulses of the same width, hunting due to overcontrol occurs when the pulse width is large when the controlled variable approaches the control target value. The disadvantage is that it is easy to occur. With conventional servo motor control devices that control using pulses whose pulse width decreases as the target value approaches, hunting is less likely to occur, but the pulse width becomes too small near the target value and enters the servo motor's dead zone. Showdown? There is a drawback that the servo motor stops operating without the amount of B reaching the target value.

The present invention has been made in consideration of the above circumstances, and
It is an object of the present invention to provide a servo motor control device that can prevent hunting of a servo motor, prevent the servo motor from inoperating due to variations in the operating dead zone of the servo motor, and control the servo motor with the minimum pulse width for operation. purpose.

(Means for Solving the Problems) In order to achieve the above object, the servo motor control device according to the present invention changes the pulse width when the deviation between the controlled variable and the control target value is less than or equal to the set value. The present invention is characterized in that it includes a control pulse output section that supplies gradually increasing control pulses to the drive circuit of the servo motor.

In the present invention, when the deviation between the controlled quantity and the control target value is 1 set value or more, the control pulse has a constant pulse width as in the conventional case, or the pulse gradually increases as the controlled quantity approaches the control target value. Just supply a control pulse whose width becomes smaller to the servo motor drive circuit and perform the same control as before (L).

(Function) According to the present invention, when the deviation between the controlled variable and the control target value becomes equal to or less than the set value, the control pulse output section operates the servo motor in a direction to eliminate the deviation, and the pulse width gradually increases. When the magnitude relationship between the controlled variable and the control target value is reversed, the servo motor is operated in the opposite direction, and a control pulse whose pulse width gradually increases is output. The output of the control pulse is stopped when the controlled variable matches the control target value. By gradually increasing the pulse width of the control pulse in this way, overcontrol and hunting caused by this can be prevented. At the same time, by increasing the pulse width to the minimum required extent, it is possible to escape from the servo motor's operation dead zone, and it is possible to prevent the servo motor from inoperating due to variations in the servo motor's operation dead zone. can be controlled.

(Example) The drawing shows an example of the present invention, and (1) shows a heat exchanger (2).
) and a bypass path (4) parallel to the heat exchanger (2).

(5) is a heating device such as a burner that heats the heat exchanger (2), and (6) is a capacity control device such as a gas proportional valve that controls the amount of heat generated by the heating device (5). (7) is a water temperature detector installed on the inlet side of the hot water supply circuit (1) to detect the temperature of the supplied water, and (8) is a water temperature detector installed on the outlet side of the hot water supply circuit (1) to detect the mixed water temperature. It is a temperature detector. (9) is a heat exchanger (
This is a flow rate detector that detects the flow rate to 2), and is arranged in the heating path (3). QCI is a mixing valve provided in the bypass M(4) to adjust the mixing ratio of hot water and water. συ is a temperature setting device. (The temple is the control circuit section, and the water temperature detector (7)
The heat quantity control unit μs operates the capacity control device (6) based on the signals from the flow rate detector (9) and the temperature setting device aη, and the mixing valve α is activated based on the signals from the temperature setting device and the hot water temperature sensor (8). Control/set the control pulse width of the servo motor that drives the
<Built-in pulse output section a4. a9 is a water governor that limits the maximum flow rate, αQ is a motor drive zc, and Q7) is a servo motor.

The operation of the above configuration will be explained. The supplied water is divided into a heating path (3) and a bypass path (4). Heating path (
In 3), the water temperature detector (7) detects the inlet water temperature (To), the flow rate detector (9) detects the flow ff1 (QH), and sends a signal to the heat amount control section 03. In the heat quantity control unit Q3, the temperature setting device aυ
The amount of gas to be combusted by the heating device (5) is calculated from these data together with the signal, and a signal is sent to the capacity control device (6) to cause the amount of gas to flow. Then, the water flowing through the heating path (3) is heated by the heat exchanger (2), and in anticipation of the cold water mixture, the water is brought to a temperature slightly higher than the set temperature (TS). It is then mixed with cold water, and the water temperature after mixing (TM
) is detected by the hot water temperature detector (3), and the control pulse output unit (141) calculates the control pulse width of the servo motor αη and operates the mixing valve GO. For example, T
When discharging hot water for 51/min at S-40℃, heating path (3)
The hot water is discharged at 50℃, and the water input temperature is T.

When the temperature is −20° C., the heating path (3) requires 3.317 minutes, and the bypass path (4) requires 1.717 minutes. Therefore, the capacity control device (6) flows the amount of gas corresponding to the hot water discharged at 50° C., and the mixing valve aCt throttles the amount of bypass water to 1.777 minutes.

Next, the operation of the control pulse output section will be explained. The control pulse width of the servo motor ση is set in proportion to the square of the deviation (TS-TM) between the mixed hot water temperature and the set hot water temperature. That is, when the deviation is large, the control pulse width is made large, and when the deviation is small, the control pulse width is made small, in order to improve responsiveness and prevent hunting. Then, as shown in the 70-chart of FIG. 3, it is determined whether or not the deviation is less than the set value/(Difference M fft at which hunting becomes a problem with the control pulse width set above due to the deviation) Fl
), in the case of a negative answer, the control pulse width F2), in the case of an affirmative answer, the pulse width is calculated to gradually increase CF3), and the control pulse width is
A control pulse having a pulse width calculated as 0Qf9 is output (F4). That is, when the difference between the mixed hot water temperature and the set hot water temperature is larger than X [region A in Fig. 4 (1)], the driving l0QQ of the servo motor ση has a pulse width proportional to the square of the deviation. Supply a control pulse to reduce the difference between the set hot water temperature and the mixed 4j temperature, and if the difference between the mixed hot water temperature and the set hot water temperature becomes X or less [region B of 4th 1(1)], gradually supplying a control pulse with a pulse width that increases to
Servo motor 0η does not operate.Due to variations in band 11, servo motor σ closes to it+ when the water temperature reaches the set water temperature.
When η is prevented from stopping and the magnitude relationship between the set hot water temperature and the mixed hot water temperature is reversed [region C in Fig. 4 (1)], the servo motor αη is increased.

Drive the servo motor in the reverse direction to the mechanical drive mechanism CaQ, supply control pulses with gradually increasing pulse width to quickly eliminate overshoot, and output control pulses when the mixed hot water temperature matches the set hot water temperature. will be stopped.

(Effects of the Invention) As explained in the above embodiments, according to the present invention, when the difference between the controlled variable and the control target value becomes less than a certain value, the pulse width is gradually increased until the two match. Since this control is adopted, hunting can be prevented, and servo inoperation due to variations in the operation dead zone of the servo motor can be prevented. Furthermore, the servo motor can be controlled even with the minimum operating pulse width.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is a block diagram of the control circuit section, Fig. 3 is a main part 70-char of the control circuit section, and Figs. It is an explanatory view showing the relationship between pulse width and hot water temperature on the side. 04)... Control pulse output section QG... Drive IC (drive circuit) Hit... Surza motor

Claims (1)

[Claims] In a device that outputs a control pulse with a pulse width calculated according to a deviation between a controlled variable and a control target value to a servo motor drive circuit, the deviation is compared with a set value, and if the deviation is less than the set value, the pulse width is determined. A servo motor control circuit comprising a control pulse output section that outputs a control pulse that gradually increases.