JPH0594648U - Water heater controller - Google Patents

Abstract

(57) [Summary] [Purpose] To control the hot water temperature of the water heater by fuzzy reasoning. [Configuration] The deviation calculation unit 18 calculates the deviation based on the detected temperature of the hot water discharged from the water heater and the set temperature, and the change rate calculation unit 19 calculates the temporal change rate of the deviation. The deviation grade calculator 22 calculates the deviation grade gE from the deviation E, and the change rate grade calculator 23 calculates the change rate grade gΔE from the change rate ΔE. The variate grade calculating unit 25 calculates the variate gΔV from the deviation grade gE and the change rate grade gΔE using a control rule, and the operation variate calculating unit 27 obtains each operation variate from each of the variate grades gΔV. Then, the union operation of the respective operation variables is performed, the center of gravity position thereof is calculated, and the operation variable of the valve opening amount of the proportional valve functioning as an actuator is obtained by fuzzy reasoning.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a water heater control device for controlling a controlled object such as hot water temperature by fuzzy control.

[0002]

[Prior Art]

 The combustion operation of a water heater installed at home is usually performed by PID calculation. This PID calculation detects the temperature of the water supplied to the water heater, the amount of hot water supplied, the temperature at which hot water comes out of the water heater, and the like. It is intended to stably supply hot water at the set temperature by controlling the valve opening amount).

[0003]

[Problems to be solved by the device]

However, when performing combustion operation water heater by the PID calculation, in particular, during the initial pouring of the water heater, when you try tapping a large amount of water, as shown by the curve A in FIG. 6, hot water water temperature is the set temperature T _S There is a problem that the hot water temperature does not rise easily and it takes a long time for the hot water temperature to stabilize. Also, if the hot water discharge amount is too small, the hot water discharge temperature will be higher than the set temperature T _{S as} shown by curve B in the figure. There is a problem that the hot water temperature fluctuates and it takes time to stabilize, such as an overshoot that rises and then an undershoot whose hot water temperature is lower than the set temperature T _S.

In order to suppress such fluctuations in the hot water temperature as much as possible and stabilize the hot water temperature in a short time, it has been proposed to perform a combustion operation by feedforward control at the initial hot water discharge of the water heater. However, we have not yet been fully satisfied, and improvements are desired.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to enable early stabilization of the hot water temperature at the time of initial hot water discharge of the water heater and when the amount of hot water changes. It is to provide the control device of.

[0006]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, the device of the first invention comprises a deviation / change rate calculation unit that obtains a deviation between a detected value of a control target and a preset value and a temporal change rate thereof, and this deviation / change rate calculation unit. It is characterized by having a fuzzy logic operation unit that calculates the operating variable of the actuator that variably controls the controlled object by the fuzzy logic operation based on a predetermined control rule from the deviation obtained by In addition to the device of the first invention, the device of the second invention further includes a PID calculator for PID control of the controlled object and a stable area where the controlled object satisfies a predetermined condition. It is characterized by having a switching means for switching the control of the controlled object from fuzzy control to PID control at times.

[0007]

[Action]

 In the present invention having the above configuration, for example, when the hot water temperature of the water heater is controlled and the hot water temperature is controlled, the hot water temperature of the hot water heater is detected by the detection means, and the detected temperature and the preset temperature ( The deviation E from the set value) and the temporal change rate ΔE of the deviation E are obtained by the deviation / change rate calculation unit. The fuzzy logic operation unit performs a fuzzy logic operation based on the previously obtained deviation E and its temporal change rate ΔE based on a predetermined control rule, and calculates an operation variable to be applied to an actuator such as a proportional valve. As a result of applying the control signal in consideration of the operation variable to the proportional valve, the gas supply amount of fuel is controlled based on the fuzzy logic operation value, and the fuzzy control combustion operation is performed.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 10 shows the system configuration of a water heater incorporating the control device of this embodiment. In the figure, a burner 2 is arranged on the lower side of the combustion chamber 1, a gas supply passage 3 is connected to the burner 2, and the gas supply passage 3 is provided with a gas supply amount to the burner 2 by the valve opening amount. A proportional valve 4 as an actuator for controlling and a hot wire anemometer 5 for detecting the gas amount are provided. A fan 6 for supplying and exhausting air is provided on the lower side of the burner 2, and a rotation detection sensor 7 for detecting the rotation of the fan 6 and a hot-wire anemometer 8 for detecting the air volume are arranged on the fan 6, respectively. Has been done.

A heat exchanger 10 is arranged on the upper side of the combustion chamber 1, and a water supply pipe 11 is connected to the inlet side of the heat exchanger 10, and a water supply temperature sensor for detecting the water supply temperature is supplied to the water supply pipe 11. 12 and a flow rate sensor 13 that detects the amount of water input (hot water supply amount). A hot water supply pipe 14 is connected to the outlet side of the heat exchanger 10, and a hot water supply amount control valve 15 for controlling the hot water discharge amount by rotation of a gear motor and a hot water discharge temperature sensor 16 for detecting the hot water discharge temperature are connected to the hot water supply pipe 14. It is provided. The detection signals of these sensors 5, 7, 8, 12, 13, 16 are applied to the control device 17, and the control device 17 applies control signals to the actuators 4, 6, 15.

A characteristic of this embodiment is that the control device 17 has a fuzzy control means incorporated therein. FIG. 1 shows a block configuration of the first embodiment of the characteristic control device in a mode which also serves as a flow chart. In the figure, the control device 17 has a deviation / change rate calculation unit 35 and a fuzzy logic calculation unit 36. Given set temperature T_SAnd the tapping temperature T detected by the tapping temperature sensor 16 of the detecting means at every predetermined sampling time._CIs added, and the deviation calculating unit 18 uses the information to calculate the deviation E (E = T_S-T_C) Is calculated, and the result is added to the deviation grade calculation unit 22. The deviation grade calculation unit 22 obtains the grade g E from the value of the deviation E and the membership function of the fuzzy variable shown in FIG. For example, if the deviation calculated by the deviation calculator 18 is E₁When it was, this E₁The vertical line of and the intersection of NB and NS of the membership function, grade gE₁ And gE₂In this embodiment, the smaller gE ₁ Deviation E₁Determined as the grade.

On the other hand, the value of the deviation E obtained by the deviation calculation unit 18 is also added to the change rate calculation unit 19, and this change rate calculation unit 19 is provided to the memory 20 at the time of the previous sampling. The temporal change rate ΔE of the deviation E is calculated from the value of the deviation at the current time and the current deviation, and the calculated value is added to the change rate grade calculation unit 23. The rate-of-change grade calculation unit 23 obtains the fuzzy variable grade gΔE by referring to the fuzzy variable membership function shown in FIG. For example, when the rate of change of the deviation E added from the rate of change calculation unit 19 is ΔE ₁ , gΔE ₁ and gΔE ₂ are obtained from the intersection of the vertical line of this rate of change ΔE ₁ and NS and ZO of the membership function. Be done. Since the smaller grade of gΔE ₁ and gΔE _{2 is used} for the minimum calculation, the value of gΔE ₂ is determined as the grade value for the rate of change ΔE ₁ .

The variate grade calculation unit 25 calculates the deviation grade gE added from the deviation grade calculation unit 22 and the change rate grade gΔE added from the change rate grade calculation unit 23, and a control rule previously given to the memory 26. Based on the above, the minimum value of the variable grade gΔV is calculated. That is, the memory 26 stores the control rules shown in Table 1.

[0013]

[Table 1]

These control rules a to k respectively correspond to points a to k on the temporal change curve of the hot water discharge detection temperature T _C shown in FIG. Specifically, these control rules are collectively stored as a fuzzy table as shown in Table 2.

[0015]

[Table 2]

In Table 1 and Table 2, Z0 is zero, NB is large in the negative direction, NS is small in the negative direction, PS is small in the positive direction, and PB is large in the positive direction. is doing.

In the case of the above example, when the minimum value of the variable grade gΔV is obtained using the membership function of the fuzzy variables shown in FIGS. 2 and 3 which is previously given to the control rule and the memory 28, the following is obtained. . First, when the deviation is E ₁ , the line of E ₁ intersects NS and NB as shown in FIG. 2. Therefore, the deviation E applies to NS and NB according to the control rule of Table 1 above. If d is selected, then the case of d, e, and i is obtained. Similarly, when the rate of change with time is ΔE ₁ , as shown in FIG. 3, the line of ΔE ₁ intersects NS and Z0. In the control rule of Table 1, when the deviation temporal change ΔE is NS and Z0, e, g, i are obtained, and both the deviation E and the temporal change ΔE are applicable. Those that are present are the control rules e and i, and using this control rule e and i, the random grade gΔV is obtained by the minimum operation of the grade obtained using the membership functions of FIGS. 2 and 3.

That is, as shown in FIG. 4, a region ABCD surrounded by a horizontal line of grade gE ₁ and a triangle line of NS according to the control rule (ΔV = N S) is obtained, and then a horizontal line of grade gΔE ₂ and NS The area AEFD surrounded by the triangle and is obtained. Then, each value (area) of the obtained operation variable is added to the union operation unit 29. The union operation unit 29 obtains the union of the ABCD area and the AEFD area. Since the area AEF D is included in the area ABCD, in this case, the area ABCD is obtained as the value (area) of the union operation result. Based on the result of this union calculation, the center of gravity calculating section 30 finds the center of gravity of the area ABCD, finds the value ΔV ₁ of this center of gravity position as the operation variable for setting the tapping temperature to the set temperature, and this operation variable ΔV (ΔV = ΔV ₁ ) is added to the control output calculator 37.

The control output calculation unit 37 drives the drive current V of the valve opening amount to be added to the proportional valve 4 as an actuator according to whether the tapping temperature T _C is higher or lower than the set temperature T _{S. 2} is increased or decreased by ΔV (ΔV ₁ ) to the drive current value V ₁ at the time of the previous sampling to calculate V ₂ = V ₁ + ΔV ₁ , and the calculation result V ₂ is added to the actuator drive circuit 31. The calculation of the proportional valve drive current is performed every sampling cycle of the tap water temperature.

The actuator drive circuit 31 adds the drive current of the value calculated by the control output calculation unit 37 to the proportional valve 4 as an actuator, and controls the gas supply amount by changing the valve opening amount of the proportional valve 4. , Stabilize the hot water temperature.

The graph shown by the solid line in FIG. 6 shows the temperature characteristics when the hot water temperature of the hot water supply device is controlled by the fuzzy control of this embodiment. By performing fuzzy control, during the initial hot water discharge of the water heater, the hot water temperature rises rapidly with the passage of time and reaches the set temperature T _S in a short time, and the overshoot and Stable hot water temperature control without undershoot is possible. Also, in the stable region of the hot water temperature after the hot water temperature reaches the set temperature, relatively good temperature characteristics are obtained.

FIG. 7 shows a second embodiment of the present invention. In this embodiment, a PID calculator 32 and a switching means 34 are provided in addition to the fuzzy control components of the first embodiment, and when the hot water temperature enters a stable state after the initial hot water discharge of the water heater. , The control of the hot water temperature from fuzzy control to PID control (in this specification, the term of PID control is used in a broad concept including both the case of pure PID control and the case of using it in combination with feedforward control). The configuration is the same as that of the first embodiment described above.

The switching means in this embodiment is configured to have a control switching determination unit 33 and a switching switch 34, and the control switching determination unit 33 has a control rule and a variation grade calculation unit 25 given to the memory 26. When the condition of the rule k shown in Table 1 is satisfied based on the result of the calculation of the variable grade, the variable grade gΔV calculated by the variable grade calculator 25 is close to 1, that is, FIG. With the membership function shown in, when gΔV is near the top P of the triangle of Z0 and the operation variable ΔV is close to zero, it is determined that the hot water temperature of the hot water supply has entered a stable state, A switch changeover signal is applied to the changeover switch 34. The changeover switch 34 changes the signal applied to the actuator drive circuit 31 from the fuzzy control side to the PID calculation section 32 side when the changeover signal is applied from the control changeover determination section 33, and after the hot water temperature stabilizes. Combustion control is performed by PID calculation control.

At the time of initial hot water discharge of the water heater, by controlling the hot water temperature of the hot water by fuzzy control, as shown in FIG. 6, the responsiveness is fast and the overshoot and It is possible to achieve good hot water temperature control without undershoot, but if fuzzy control is continued after the hot water temperature enters the stabilization area, the change in hot water temperature in the hot water temperature stabilization area When the state is enlarged, there is some change in the hot water temperature as shown by the dotted line in FIG. Of course, it is possible to prevent such fluctuations in the bath temperature by increasing the number of labels in the membership function and performing fine fuzzy inference. A large-capacity memory for storage is required, and the device configuration becomes complicated, resulting in a high device cost. After the hot water temperature enters the stabilization region, it is preferable to control the hot water temperature by PID calculation, because the hot water temperature can be controlled more stably with a simple device configuration. In this embodiment, when it is determined that the hot water temperature has entered the stabilization region, the fuzzy control is switched to the PID control, so that the fluctuation of the hot water temperature is suppressed as shown by the solid line in FIG. More stable control of the hot water temperature is possible.

FIG. 8 shows a third embodiment of the present invention. In this embodiment, as in the case of the second embodiment, the hot water temperature is controlled by fuzzy control during the initial hot water discharge of the water heater, and after the hot water temperature stabilizes, the fuzzy control is switched to the PID control. It is composed. Similar to the second embodiment, this embodiment is provided with a control switching determination unit 33 and a changeover switch 34, but determines that the hot water temperature has entered the stable region from the initial hot water supply of the water heater. The control switching determination unit 33 is configured to perform determination based on the control rule of the memory 26, the deviation grade gE calculated by the deviation grade calculation unit 22, and the change rate grade gΔE calculated by the change rate grade calculation unit 23. The other structure is the same as that of the second embodiment.

The control switching determination unit 33 satisfies the condition of the control rule k given in advance in the memory 26, the grade gE becomes a value close to 1, and the grade gΔE becomes a value close to 1. When it is determined that the hot water temperature has reached a stable state by fuzzy control, a changeover signal is added to the changeover switch 34. In response to this changeover signal, the changeover switch 34 changes over the signal applied to the actuator drive circuit 31 from the signal from the center of gravity calculating section 30 to the signal from the PID calculating section 32. Then, the hot water temperature of the hot water supply device is controlled.

Also in the case of the third embodiment, as shown by the solid line in FIG. 9, it is possible to perform fine control with almost no fluctuation in the hot water temperature in the stable region of the hot water temperature.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in each of the above-described embodiments, the sum of the operation variables calculated by the operation variable calculator 27 is calculated, and the operation variable ΔV is calculated from the position of the center of gravity of the sum, but it is calculated by the operation variable calculator 27. The product set may be obtained based on the operation variable, and the operation variable ΔV may be obtained from the barycentric position of this product set.

Further, in each of the above embodiments, the shape of the fuzzy variable (membership function) is a triangular shape, but the fuzzy variable may have a bell shape as shown in FIG. It is possible to perform fuzzy inference using fuzzy variables of various shapes other than.

Further, in each of the above-described embodiments, the controlled hot water temperature is set as the hot water discharge temperature, and the relative valve 4 is controlled as an actuator. However, as shown in Table 3, the controlled hot water flow amount, fan rotation speed, burner The gas flow rate added to 2 and the air flow rate of the fan may be controlled. In this case, for example, when controlling the amount of hot water to be discharged, the amount of hot water discharged is detected by the flow rate sensor 13, the deviation and the temporal change rate of the deviation are obtained from the detected amount of hot water discharged and the set amount of hot water discharged, and the gear motor as an actuator When controlling the rotation speed of the fan 6, the rotation detection sensor 7 detects the rotation speed of the fan 6, and the deviation between the detected rotation speed and the set rotation speed and its temporal change rate. The fan 6 may be used as an actuator to control the fan rotation speed. Alternatively, when controlling the gas flow rate as a control target, the hot wire anemometer 5 detects the gas flow rate supplied to the burner 2, From the values of the detected gas flow rate and the set gas flow rate, the deviation and the rate of change over time are obtained to control the opening amount of the proportional valve 4 as an actuator. Further, when the air amount of the fan 6 is to be controlled, the air amount of the fan 6 is detected by the hot wire anemometer 8 and the deviation and the difference are similarly detected from the detected air amount and the set air amount. The rotation rate of the fan 6 as an actuator may be controlled by obtaining the rate of change with time, and various control targets of the water heater can be controlled by applying the control device of the present invention.

[0031]

[Table 3]

Further, in the present embodiment, the difference (operational variable ΔV) is calculated, and this is added to the control output calculation unit 37, and the drive output of the actuator is calculated by this control output calculation unit 37. The absolute value) may be directly obtained by fuzzy inference to drive and control the actuator. In this case, the zero point on the horizontal axis in FIGS. 2, 3 and 4 is at the left end.

[0033]

[Effect of the device]

 The present invention is configured to obtain the deviation and its temporal change rate from the detected value and the set value of the controlled object and to control the controlled object by fuzzy logic operation. In the case of control, the hot water temperature at the initial hot water discharge of the water heater can be stabilized at the set temperature quickly without causing a large change in hot water temperature due to overshoot or undershoot. The temperature characteristics can be greatly improved.

Further, when the control target is switched from the fuzzy control to the PID control when the control target enters the stable region, a wide range from the initial operation of the water heater to the stable operation state is provided. The controlled object can be controlled more accurately and stably in the area, and the control performance of the water heater can be significantly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a controller of a water heater according to the present invention.

FIG. 2 shows the grade g by the fuzzy reasoning of the same embodiment.
It is explanatory drawing of the membership function which calculates | requires E.

FIG. 3 shows a grade g according to the fuzzy reasoning of the embodiment.
It is explanatory drawing of the membership function which calculates | requires (DELTA) E.

FIG. 4 shows a grade g based on the fuzzy reasoning of the embodiment.
It is explanatory drawing of the membership function which calculates | requires (DELTA) V.

FIG. 5 is a graph showing a temporal change of a detected temperature value in the example.

FIG. 6 is an explanatory diagram showing a hot water outlet temperature characteristic of the water heater in the same example in a comparative state with a conventional example.

FIG. 7 is a block diagram showing a second embodiment of the present invention.

FIG. 8 is a block diagram showing a third embodiment of the present invention.

FIG. 9 is a graph showing the temperature characteristics of the second and third embodiments in comparison with the case of fuzzy control in the hot water temperature stable region.

FIG. 10 is a system diagram of the water heater according to the present embodiment.

FIG. 11 is an explanatory diagram of another shape of a membership function that performs fuzzy inference.

[Explanation of symbols]

 4 Proportional valve 16 Hot water temperature sensor 18 Deviation calculator 19 Change rate calculator 20, 21, 24, 26, 28 Memory 22 Deviation grade calculator 23 Change rate grade calculator 25 Variable grade calculator 27 Operation variable calculator 29 Union set Calculation unit 30 Center of gravity calculation unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Naoki Obayashi 3-4, Fukamidai, Yamato-shi, Kanagawa Inside Gaster Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A deviation / change rate calculation unit for obtaining a deviation between a detected value of a controlled object and a preset value and a temporal change rate thereof, and a deviation obtained by the deviation / change rate calculation unit and its deviation A controller of a water heater having a fuzzy logic operation unit that calculates an operation variable of an actuator that variably controls a control target from a temporal change rate by a fuzzy logic operation based on a predetermined control rule. 2. A deviation / change rate calculation unit for obtaining a deviation between a detected value of a controlled object and a preset value and a temporal change rate thereof, and a deviation obtained by this deviation / change rate calculation unit and its deviation A fuzzy logic operation unit that calculates an operating variable of an actuator that variably controls a control target by a fuzzy logic operation based on a predetermined control rule based on a temporal change rate, a PID calculation unit that PID-controls the control target, and a predetermined control target And a switching means for switching the control of the controlled object from the fuzzy control to the PID control when entering the stable region satisfying the condition of.