JPS62217051A - Controller of hot water supplier - Google Patents

Abstract

PURPOSE:To stabilize the temperature of hot water supply by multiplying the rate of feed-forward elements before and after the variation of respective input values to a feed-forward operating part by integral components of a feedback operating part, and resetting the multiplied values as integral components immediately after the variation of the multiplied values. CONSTITUTION:When a supply hot water temperature Ts, an incoming water temperature Tc, and a supply hot water quantity Q have varies, a feed-forward operating portion 10 immediately calculates a feed-forward element Gff. The value of the element Gff is given to integrated value correcting means 16, and a division operator 16a calculates the rate of feed-forward elements before and after the variation. Successively, this ratio is multiplied by an integral component Gi. This multiplied value is reset as an integral component G'i immediately, after the variation. Accordingly, in accordance with the varied components of respective inputs Ts, Tc and Q, the integral component Gi of the feedback operating portion 14 are corrected to appropriate values, and hence no time lag is produced in the outputs of the respective operation results of the operating portions 10 and 14. Therefore, overchuting is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for water heaters and the like that eliminates variations in hot water output characteristics due to differences in the efficiency of appliances for each product.

<Conventional technology> Conventional control devices for water heaters, etc.
Feedforward elements calculated from hot water m etc., and P
In order to perform the ID operation, there is a system in which the heat amount of the burner is controlled by a combined output with a feedback element calculated based on the amount of hot water discharged and the deviation between the set temperature and the hot water temperature.

Now, the incoming water temperature is Tc, the hot water setting temperature is Ts, the hot water output is Q1, the hot water temperature is Th, and the feedforward element is Gfr.
, the feedback element is G fb, and the composite value of both elements is G
Assuming that the integral component forming the feedback element Gfb is Gi, the proportional component is Gp, and the differential component is Gd, the following relational expression holds between them.

G=Off'+Gfb (1)
Gff=Kff'・(Ts-Tc:l Q
(2) Gfb= G p+ G i+ G d
(3) Gp=Kp(Ts-Th)・Q
(4) Gt=Ki (Ts-'I'h)・
Q-dt (5) Gd=Kd-d(Ts-Th
)・Q/dt (6) However, Kff, K
p, KiXKd are proportionality constants.

By the way, in a steady state, the difference between the hot water outlet temperature Ts and the outlet a temperature Th is minimum, and therefore, in the feedback element Gfb, only the integral component Gi becomes an effective value. Therefore, the control value G in the steady state can be considered as G = G rr + G i .

When at least one of the set hot water temperature Ts, the inlet water temperature Tc, and the hot water output Q changes from this state, the change can be detected immediately, so the feedforward element Gl'f
is followed and changed to an appropriate value within a short time, but it takes time for the tap water temperature Th to show that change.

therefore. In the conventional control device, a time lag occurs in the control operation between the output of the feedback element Gfb and the output of the feedforward element Gff, and as a result, for example, when the feedforward element Gf'r changes significantly in the decreasing direction, Feedback element Gr for this
b, especially the ratio of the integral component Gi may become so large that appropriate temperature control may not be possible. As a result, as shown in FIG. 2, there was a problem in which the temperature of the hot water greatly overshot.

In order to prevent this, the feedforward element Gf
A threshold value is set for r, and when the hot water output amount 01, the hot water set temperature Ts, the incoming water temperature Tc, etc. change greatly and the feedforward element GCf exceeds the threshold value, a portion of the integral component Gi of the feedback element Gfb is set. Alternatively, a device has been proposed in which the output value G is controlled so as not to cause a sudden change by temporarily canceling all of them (see, for example, Japanese Patent Application Laid-open No. 159553/1983). In such a device, the threshold value is uniquely set, so if, for example, there is a difference in thermal efficiency, etc. of each water heater, the hot water output characteristics will differ greatly for each water heater. Therefore, in order to control each water heater to an appropriate hot water output temperature, the hot water output characteristics of each water heater must be readjusted.

<Objective of the Invention> The present invention solves the above-mentioned problems, eliminates variations in hot water output characteristics due to differences in thermal efficiency, etc. of each water heater, and enables stable control of hot water output temperature in each water heater. The purpose is to

<Configuration of the Invention> In order to achieve the above-mentioned object, the present invention includes a feedforward calculation unit that calculates a feedforward element based on incoming water temperature, outgoing hot water temperature, outgoing hot water amount, etc., and a deviation between set temperature and outgoing hot water temperature. In a combustion control device such as a water heater, which has a feedback calculation unit that calculates a feedback element by performing PID calculation and calculation on An integral value correcting means is provided which multiplies the integral component of the feedback calculation section by the ratio and resets the multiplied value as the integral component immediately after the change.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of a combustion control device for a water heater or the like according to an embodiment of the present invention. In the figure, the symbol l indicates the entire combustion control device, and 2 indicates the preset hot water temperature Ts.
A hot water temperature setting device that outputs a set temperature signal corresponding to 4.
6 is an incoming water temperature detector that detects the incoming water temperature Tc and outputs a signal corresponding to the incoming water temperature Tc; 6 is an outgoing hot water amount detector that detects the outgoing hot water amount Q and outputs a corresponding outgoing water amount signal; and 8 is an incoming water temperature detector that detects the outgoing water temperature Th. This is a hot water temperature detector that detects and outputs a corresponding hot water temperature signal.

IO is a feedforward calculation unit that calculates a feedforward element Gf by inputting signals of set temperature Ts, water inlet temperature Tc, and hot water output amount Q; 14 is a deviation Δ(=Ts−) between set temperature Ts and outlet temperature Th; This is a feedback calculation unit that calculates the feedforward element Gfb based on the values of the hot water supply amount Q and the set temperature Ts.The feedback calculation unit 14 calculates the deviation Δ(=Ts−Th ), a subtracter 14S1 that calculates the integral component Gi of this deviation Δ(=Ts-Th), a proportional calculator 14p that calculates the proportional component Gp of the deviation Δ, a differential component Gd of the deviation Δ Each calculation output Gi of the differential calculator 14d to be calculated, the integral value correction means 16, the proportional calculator 14p, and the differential calculator 14d, which will be described later.
′, Gp, and Gd to form the feedforward element Gf
and a first adder 14a that calculates b.

Further, 16 is an integral value correcting means, and this integral value correcting means 16 is configured to adjust the ratio Gff2 of the feedforward elements before and after the change when the human power values Ts, Tc, and Q to the feedforward calculation unit IO change. /G ff1(ko, :: +, :, Gfflha change, G plane f2t*each feedforward element after change) and the above-mentioned ratio G obtained by this division calculator 16a. ff2/G ff, feedback calculation unit 1
and a multiplier 16b that multiplies the integral component Gi calculated by the four integral calculators 14i and outputs the multiplied value.

18 is a feedforward element Off which is the calculation result output of the feedforward calculation unit 10 and a feedback element Gr which is the calculation result output of the feedback calculation unit 14.
The control value G (= G ff + G fb
) is a proportional control valve that adjusts the opening degree of the burner based on the control value G obtained by the second adder 18.

Therefore, in the control device l for a water heater, etc. of the present invention, the hot water temperature setting device 2, the inlet water temperature detector 4, and the hot water amount detector 6
From the hot water setting temperature Ts.

Signals corresponding to the incoming water temperature Tc and the outgoing water amount Q are input to the feedforward calculation section 10. Then, the value of the feedback element Gff, which is the calculation result output of the feedforward calculation unit IO, is sequentially given to the 2 adder 18 and the integral value correction means 16. On the other hand, the hot water setting temperature Ts is determined from the hot water temperature setting device 2, the hot water amount detector 6, and the hot water temperature detector 8, respectively.

Out? Jh Signals corresponding to insect Q and hot water temperature Th are input to the feedback calculation unit 14. The subtracter 14s of the feedback calculation unit 14 calculates the deviation Δ (=Ts - Th) between the set hot water temperature Ts and the hot water temperature Th, and provides this deviation Δ to each calculation unit 14i, 14p, 14d, so that each calculation The integral component Gi, the proportional component Gp1, and the differential component Gd are calculated by the devices 14i, 14p, and 14d from the deviation Δ and the value of the hot water output Q based on the equations (4), (5), and (6), respectively. Then, the value of the integral component Gi is determined by the multiplier 16
b, the proportional component Gp and the differential component Gd are added to the first adder 14a.
will be added to each.

Now, when at least one of the hot water supply temperature Ts, the water input temperature Tc, and the hot water output amount Q changes, the signals corresponding to these are immediately input to the feedforward calculation unit 10, so the feedforward calculation unit 10 A feedforward element Gff is calculated based on equation (2). Then, the calculated value of the feedforward element Off is given to the integral value correction means 16. The division calculator 16a of the integral value correction means 16 calculates the ratio of the feedforward elements before and after the change Gff2/Off, (here, G
ff is before the change, Off is each feedforward element after the change), and then the integral component Gi is multiplied by the ratio G f'f,/G ff in the next stage multiplier 16b.

'L, rih<tte, G t-G frz/ G ff+
The value of G is reset as the integral component Gi° immediately after the change.

Then, the reset integral component Gi'' is added to the first adder 14.
d, and is added to the proportional component Gp and the differential component Gd to calculate the feedback element Gfb. The feedback element Gfb and feedforward element Off thus calculated are added to the second adder 18.
It is added to the proportional control valve 20 as a control value G (=G fl'+G fb), and the opening degree of the proportional control valve 20 is controlled.

In this way, when each human power TsSTcSQ to the feedforward calculation unit 10 changes, the integral component Gi of the feedback calculation unit 14 is immediately adjusted to an appropriate value according to the change, so that the feedforward calculation Part 10
There is no time lag between the output of each calculation result from the feedback calculation unit 14 and the feedback calculation unit 14. Therefore, overshoot as in the conventional example can be significantly reduced.

<Effects of the Invention> In the combustion control device for a water heater or the like of the present invention, when each input to the feedforward calculation section changes, the integral component of the feedback calculation section is multiplied by the ratio of the feedforward elements before and after the change. , an integral value correction means is provided to reset the multiplied value as the integral component immediately after the change, so when each input to the feedforward calculation section changes, the integral component of the feedback calculation section is changed according to the change. is immediately corrected to the appropriate value without any time lag. Therefore, overshoot and undershoot from a steady state can be reduced, and easy-to-use hot water tapping characteristics can be obtained. Furthermore, since the temperature can be controlled according to the hot water supply characteristics of each appliance, there will be no variation in the hot water supply characteristics of each appliance due to differences in the thermal efficiency of each appliance.

Moreover, since the integral value correcting means only performs multiplication and division, it is simple in terms of software even when controlled by a microcomputer, and provides excellent effects such as being easy and inexpensive to implement.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a combustion control device according to the present invention, and FIG. 2 is a characteristic diagram of combustion control. I...Control device for water heater, etc., 1. Q: Feedback λ-word calculation unit, 14: Feedback calculation unit, 141: Integral calculation unit, 16: Integral value correction means.

Claims (1)

[Claims] (1) A feedforward calculation unit that calculates a feedforward element based on incoming water temperature, hot water exit temperature, hot water output amount, etc., and a feedback calculation unit that calculates a feedback element by performing PID calculation on the deviation between the set temperature and the hot water exit temperature. In a control device for a water heater, etc., which has: when each input value to the feedforward calculation section changes, the ratio of the feedforward elements before and after the change is multiplied by the integral component of the feedback calculation section, and the multiplied value is calculated. A control device for a water heater, etc., characterized in that it is provided with an integral value correction means for resetting an integral component immediately after a change.