JP3282169B2 - Combustion device fan motor control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a fan motor for supplying air to a combustion device.

[0002]

2. Description of the Related Art In a combustion device such as a gas water heater,
A general control method of the fan motor includes a feedforward term determined in advance based on the target rotation speed and a feedback term which is a result of a proportional integral calculation of a deviation between the target rotation speed and the actual rotation speed of the fan. The fan speed is controlled based on the added value. Here, the feed-forward term serves to quickly increase the fan speed, which is important for igniting the prepurge early in the combustion device to accelerate ignition.

In this control method, the feedforward term needs to be set to an optimum value in order to start the fan rotation speed in the shortest time. Conventionally, as a method for setting the feedforward term to the optimum value,
For example, there is one disclosed in JP-A-4-225717. In this conventional method, at the time of pre-purge, the fan is sequentially rotated at a plurality of different rotation speeds, the above-mentioned optimum value is calculated from the operation amount at each rotation speed, and this is stored as a new feedforward term.

[0004]

In the conventional method, in addition to the normal control sequence, it is necessary to perform the above-described special sequence for learning the optimum value of the feedforward term at the time of prepurge. Therefore, there is a problem that the control sequence is complicated as a whole, and there is a problem that a pre-purge time is lengthened to execute the above-described special sequence and an ignition timing is delayed.

Accordingly, it is a main object of the present invention to optimize the feed forward term in the fan motor control of the combustion apparatus without complicating the control sequence at the time of prepurge and without delaying the ignition timing. The purpose is to be able to learn values.

Another object of the present invention is to enable the entire processing of the fan motor control including the above learning to be performed with an algorithm as simple as possible.

Another object of the present invention is to ensure that the optimum value can be learned in the above learning, that is, to prevent learning by passing a value that is not optimal.

[0008]

A fan motor control system for a combustion apparatus according to the present invention is applied to control of a fan motor for supplying air to the combustion apparatus. Integral calculating means for integrating a value related to a deviation from the rotational speed and corresponding to the ratio of the rotational speed deviation to the target rotational speed, and proportional calculating means for performing a proportional operation of the ratio equivalent value And the integral value of the ratio equivalent value from the integral operation means and the proportional operation value from the proportional operation means and the numerical value 1 to calculate a feedforward coefficient. Is multiplied by a value corresponding to the rotation speed of the fan motor based on the multiplied value. Motor control means for determining whether or not the fan motor rotation speed is in a stable state at a predetermined fan motor control opportunity, and storing an integral value of the ratio equivalent value in a stable state as an optimum integral value. The integrated value storage means, and the stored optimal integrated value, as it is, as the initial value of the integrated value to be used at another fan motor control opportunity other than the predetermined opportunity, And an integration initial value setting means for setting the integration calculation means at the start of the operation.

[0009]

In the above arrangement, setting the integral initial value at the start of the fan motor control opportunity is equivalent to determining the feedforward term at the control opportunity. As the integration initial value, the optimal integration value learned at another control opportunity performed in the past is used as it is, so that there is no need to perform learning at the control opportunity. That is, in the combustion device, it is necessary to appropriately set the initial integration value at the start of the prepurge,
Since the optimum integration value learned in the past is used as it is as the integration initial value, a learning sequence is unnecessary at the time of prepurge. Therefore, the pre-purge can be completed in a short time and the ignition can be promptly performed.

[0010] When determining an initial integration value at a control opportunity from an optimal integration value learned at a past control opportunity,
The difference in the target speed between the past control opportunity and the control opportunity has to be taken into account. If the target rotational speeds are different, the optimum integral value of the rotational speed deviation at the past control opportunity cannot be used as it is as the integral initial value of the rotational speed deviation at the control opportunity. In order to solve the problem caused by the difference in the target rotation speed, in the present invention, the integration operation is not performed directly on the rotation speed deviation but on the ratio between the rotation speed deviation and the target rotation speed. Is multiplied by the target rotational speed to obtain the manipulated variable. In this way, even if there is a difference in the target rotational speed between the past control opportunity and the control opportunity, the optimal integration value learned at the past control opportunity can be used as it is as the integration initial value at the control opportunity. There is an advantage that an algorithm for processing is simplified.

Normally, fan motor control is performed by a combination of feedforward control that is effective for quickly starting the rotation speed and feedback control that is effective for highly accurate control of the rotation speed. The feedback control is P
I control is common. Also in the present invention, the feedforward control and the PI control are combined. As a specific calculation method, a PI calculation is performed on the above-described ratio, and a value obtained by adding a numerical value 1 to the PI calculation result is a target rotation speed. A method of obtaining an operation amount by multiplying a number is adopted. This calculation method realizes a combination of feedback control and PI control with a simple algorithm while solving the above-mentioned problem caused by the difference in the target rotation speed.

The control opportunity at which the optimum integral value can be learned should be a control opportunity other than the prepurge to avoid learning at the prepurge. That is, it should be learned during combustion or post-purge. Among them,
The post-purge is most suitable as a learning opportunity because the target rotation speed is stable and constant, and good responsiveness and quickness of the fan control are not strictly required.

The learning of the optimum integral value is performed by storing the integral value when the fan motor speed is in a stable state. In this case, if there is an offset even in a stable state, the integrated value keeps changing, and it is not appropriate to learn this. Therefore, in order to avoid learning when there is such an offset and to ensure that only the optimum value is learned, the determination of a stable state is made based on whether or not the integrated value is substantially continuously constant. It is desirable.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a fan motor control system in which the present invention is applied to a gas water heater.

The gas hot water supply apparatus includes a hot water supply system 100 having hot water supply pipes and a burner for supplying hot water, and a control system 200 for controlling a burner combustion amount, a fan rotation speed, and the like of the hot water supply system 100. .

The hot water supply system 100 includes a burner 101, an intake fan 103, a gas supply pipe 105 to the hot water supply burner, a heat exchanger 107, a water supply pipe 109, a hot water supply pipe 110, and the like.

Here, the intake fan 103 is connected to the burner 10
1 for sending air to the fan motor 111.
Driven by In addition, the gas supply pipe 105 has a proportional valve 113 for adjusting the gas flow rate and a gas supply start / stop.
An on-off valve 115 and the like for stopping are provided.

The water supply pipe 109 is provided with a flow rate sensor 117 for measuring the flow rate Q of the water supply and an incoming water temperature sensor 119 for measuring the temperature TC of the water supply. Also, hot water supply pipe 110
Is provided with a tapping temperature sensor 121 for measuring a hot water supply temperature TH. Further, the fan motor 111 is provided with a rotation speed sensor 123 for measuring the fan rotation speed N.

The control system 200 controls the fan motor 111, the proportional valve 113, the on-off valve 115, and the like, and includes the functional elements as shown in the figure. Hereinafter, each functional element will be described.

The calorie computing unit 201 has a target tapping temperature TS set by the user from the temperature setting unit 247, a tapping temperature TC from the tapping temperature sensor 119, a feedwater flow rate Q from the flow rate sensor 117, and a tapping temperature from the tapping temperature sensor 121. In response to TH, the required amount of combustion heat F is calculated. The calculated required heat amount F is calculated by the target rotation speed calculation unit 203 and the proportional valve control unit 2.
05.

The proportional valve control unit 205 controls the proportional valve driving circuit 243 to adjust the opening of the proportional valve 113 so as to supply the burner 101 with gas in an amount corresponding to the required heat amount F.

The combustion necessity judging section 207 receives the water supply flow rate Q from the water supply flow rate sensor 117, and judges the necessity of combustion (whether or not hot water is used) based on whether or not it is larger than a predetermined minimum water supply flow rate Qmin. The post-purge control unit 221, the pre-purge control unit 222, the integral amount control unit 227, and the on-off valve control unit 239 are notified.

The pre-purge control section 222 detects the start of hot water supply based on the notification from the combustion necessity determination section 207, starts a built-in pre-purge timer, and at the same time, notifies the target rotation speed calculation section 203 and the fan. Notify the motor control unit 213. Thereafter, when a predetermined time required for the prepurge elapses, the prepurge timer counts up. Then, the prepurge control unit 222 notifies the target rotation speed calculation unit 203 and the on-off valve control unit 239 that the prepurge timer is up (end of the prepurge).

The post-purge control unit 221 detects the end of hot water supply (combustion end) based on the notification from the combustion necessity determination unit 207, starts a built-in post-purge timer, and simultaneously notifies the target rotation speed. The calculation unit 203 and the integration control unit 227 are notified. Thereafter, when a predetermined time required for post-purging has elapsed, the post-purge timer counts up. Then, the post-purge control unit 221
Notifies the fan motor control unit 213 of the post-purge timer up (post-purge end).

The target rotation speed calculation unit 203 determines the number of intake fans at the time of pre-purge, combustion, and post-purge.
First, when a notification of the start of the prepurge timer (start of prepurge) is received from the prepurge control unit 222, the target revolution number for prepurge stored in advance is output. Further, upon receiving the notification of the end of the prepurge (combustion start) from the prepurge control unit 222, thereafter, the target rotation number corresponding to the intake air amount required for combustion calculated based on the required heat amount F from the heat amount calculation unit 201 is output. . After that, when a post-purge timer start (combustion end and post-purge start) notification is received from the post-purge control unit 221, the post-purge target rotational speed stored in advance is output. Output target speed NS
Is supplied to the set pulse width calculator 209 and the subtractor 219.

The set pulse width calculation unit 209 receives the target rotation speed NS from the target rotation speed calculation unit 203, calculates a set pulse width ts proportional to the target rotation speed NS, and outputs this to the multiplier 211 and the correction ratio calculation unit 215. I do.

The actual rotational speed detecting section 237 is provided with the rotational speed sensor 1.
23 (for example, a rotary encoder) to calculate the rotation speed N of the fan motor 111,
Give to 19.

The subtractor 219 has a target rotation speed calculating section 203.
The deviation NS-N between the target rotational speed NS and the actual rotational speed N of the actual rotational speed detector 237 is determined, and this rotational speed deviation is given to the correction pulse width calculator 217. The correction pulse width calculation unit 217 calculates a correction pulse width Δt proportional to the rotational speed deviation NS−N from the subtractor 219, and outputs this to the correction ratio calculation unit 215.

The correction ratio calculation section 215 divides the correction pulse width Δt from the correction pulse width calculation section 217 by the set pulse width t S from the set pulse width calculation section 209 to obtain a correction pulse width corresponding to the set pulse width t S. Δt
The correction ratio Δt / ts is calculated, and the correction ratio Δt / ts is given to the proportional calculation unit 223 and the integration calculation unit 225.

The proportional operation unit 223 includes the correction ratio operation unit 21
A proportional operation is performed on the correction ratio Δt / ts from 5 using a predetermined proportional coefficient, and the calculated value is added to an adder 231.
Output to

The integral operation unit 225 calculates the correction ratio Δt /
An integration operation is performed on tS using a predetermined integration coefficient, and the calculated integration value is output to the adder 231.

The adder 231 adds the proportional operation value from the proportional operation unit 223 and the integral operation value from the integration operation unit 225 to obtain a PI operation value r. Output to the number stability determination unit 235.

The adder 233 adds the numerical value 1 to the PI operation value r output from the adder 231 and adds the value (r +
1) is output to the multiplier 211 as a feedforward coefficient K (K = r + 1). The multiplier 211 calculates the set pulse width ts from the set pulse width calculator 209 and the adder 233.
Is multiplied by the feedforward coefficient K from the controller, and the multiplied value ts * K is given to the fan motor control unit 213.

Although the coefficient K (= r + 1) is called a feedforward coefficient, its substance includes a feedforward operation component and a feedback operation component. That is, the feedforward operation component is a portion related to the integration constant in the PI operation value r and the numerical value 1, and the feedback operation component is the remaining portion (the proportional operation result and the integration operation result in the PI operation value r). In the section relating to definite integration). One feature of this embodiment lies in an improvement in how to learn a part related to an integration constant in a feedforward operation component.

When the fan motor control unit 213 receives the notification of the start of the pre-purge from the pre-purge control unit 222, it instructs the fan motor drive circuit 245 to output the fan motor 11
1 is started and control of the fan rotation speed N is started. In this rotation speed control, the fan motor control unit 213 controls the multiplier 211
Is controlled based on the multiplied value ts * K from Thereafter, when the post-purge control unit 221 receives a notification of the end of the post-purge, the fan motor control unit 213 instructs the fan motor drive circuit 245 to output the fan motor 1
11 is stopped.

The rotation speed stability determination unit 235 includes an adder 231
Then, it is determined whether or not the fan rotation speed N has reached the target rotation speed NS and is in a stable state, based on the PI calculation value r from. For example, it is determined that the PI calculation value r has become constant and stable over a predetermined time. This determination result is notified to the integration amount control unit 227.

The integral control unit 227 includes a combustion necessity determining unit 2
When a notification of the necessity of combustion is received from 07 (start of hot water supply), the optimal integral value is read from the optimal integral value storage unit 229, and is given to the integral operation unit 227 as an initial value (integration constant). If the optimum integration value has not been stored in the optimum integration value storage unit 229, the default value of the integration constant previously stored in the integration amount control unit 227 is stored in the integration calculation unit 22.
7 given.

When the integration amount control unit 227 receives the notification of the start of the post-purge from the post-purge control unit 221,
The monitoring of the notification from the rotation speed stability determination unit 235 is started, and when the notification that the fan rotation speed is in a stable state is input, the integration value is read from the integration calculation unit 225 at that time, and this is set as the optimum integration value. The data is written into the optimum integration value storage unit 229. In other words, each time the post-purge is performed, the integrated value at that time is learned and stored as the optimal integrated value when the fan rotation speed is stabilized. Used as a value.

It should be noted that even when the fan rotation speed is in a stable state, if there is an offset from the target rotation speed NS, the integrated value will not be constant but will continue to change. That is not appropriate. In such a case, since the PI calculation value r does not become constant, the rotation speed stability determination unit 235 does not determine that the rotation speed is stable, so that new learning is avoided and the previously integrated optimum integration value remains effectively unchanged. It is.

Upon receipt of the notification of the end of the prepurge from the prepurge control unit 222, the on / off valve control unit 239 controls the on / off valve drive circuit 241 to start combustion, and
15 is opened, and when the notification of combustion unnecessary (end of use of hot water supply) is received from the combustion necessity determination unit 207, the on-off valve 115 is closed to end the combustion.

Next, the operation flow of the fan control performed by the control system 200 under the above configuration will be described with reference to the flowchart of FIG.

The feed water flow Q from the water flow sensor 117 is periodically taken into the combustion necessity judging section 207 and compared with a minimum feed water flow Q min which is a threshold level for judging whether or not hot water is used (step). 301).

The result of this comparison is Q <Qmin to Q> Qmin
This means that the use of hot water is started. Then
Prepurge is started as follows.

First, the optimal integral value stored in the optimal integral value storage section 229 is set as an initial value of the integral amount in the integral operation section 225 (step 303). Further, the set pulse width tS is calculated by the set pulse width calculation unit 209 based on the target rotation speed NS (in this case, a predetermined prepurge rotation speed) from the target rotation speed calculation unit 203 (step 305), and The correction pulse width Δt is calculated by the correction pulse width calculator 217 based on the deviation between the target rotation speed NS and the actual rotation speed N (step 307). Then, the correction ratio Δt / ts is calculated by the correction ratio calculation unit 215, and based on this, the proportional calculation unit 223 and the integration calculation unit 2 are calculated.
At 25, a PI calculation is performed to obtain a PI calculation value r,
The numerical value 1 is added to this, and the feedforward coefficient K is calculated (step 309). Subsequently, the control of the rotation speed of the fan motor is started based on the product of the feedforward coefficient K and the set pulse width ts (step 311).

When the prepurge is started in this way, the processing from step 305 to step 311 is repeatedly executed thereafter, whereby the fan speed is controlled to the target speed NS for prepurge.

When the prepurge is completed, although not shown in the flowchart, the on / off valve 115 is opened by the on / off valve control section 239 to start combustion. During the combustion, the opening of the proportional valve 113 is adjusted by the proportional valve control unit 205 to control the amount of combustion heat to the required amount of heat F.

Simultaneously with the start of combustion, the target rotation speed NS is changed from a value for pre-purge to a value calculated based on the required heat quantity F. Thereafter, the processing from step 305 to step 311 is repeated based on the new target rotational speed NS, whereby the fan rotational speed during combustion is controlled to the target rotational speed NS suitable for the required heat quantity F.

During the combustion, if the set temperature TS or the feedwater flow rate Q changes, the required heat quantity F changes.
S is also changed. Even if the target rotation speed NS changes, the fan rotation speed favorably follows the new target rotation speed NS by repeating the processing from step 305 to step 311.

During the above processing, the comparison between the water supply flow rate Q and the minimum water supply amount Qmin is periodically performed (step 31).
3). As a result, when Q <Qmin, this means the end of hot water supply, so the on-off valve 115 is closed to stop combustion, and the fan control proceeds to step 315 to start post-purge.

At the same time as the start of the post-purge, the post-purge timer is started (step 315), and the target rotation speed N is set.
A predetermined post-purge rotation speed NP is output as S (step 317). Based on this target rotational speed NP,
The processing from step 305 to step 311 is repeatedly executed (step 319), whereby the fan rotation speed in post-purge is controlled to the rotation speed NP.

During the post-purge, the rotation speed stability determination section 23 determines whether or not the PI operation value r output from the adder 231 has been in a constant state (stable state) for a predetermined time.
5 is checked (step 321). As a result, when a stable state is detected, the integral operation unit 22 at that time is detected.
The integrated value of the correction ratio Δt / ts calculated in step 5 is stored in the optimum integrated value storage unit 229 as the optimum integrated value (step 323). This optimum integral value is set in the integral operation unit 225 as an initial value of the integral value at the start of the next hot water tapping.

When the time of the post-purge timer expires (step 325), the fan is stopped and the post-purge ends (step 327).

In the control operation described above, one point to be noted is that the optimum integral value of PI control is learned at the time of post-purge and is used as an integral initial value at the start of the next pre-purge. That is the point. Thereby,
In the prepurge that is required to raise the fan speed to the target speed as quickly as possible, the control processing for learning as in the conventional example described above is prevented from becoming complicated,
Therefore, it becomes possible to finish the prepurge and start the combustion in a minimum time. On the other hand, post-purge is longer in time than pre-purge and does not require strict start-up of the number of revolutions, so that there is substantially no problem even if the control processing is somewhat complicated. By comparison, the learning process of this embodiment is simple.

By the way, in this embodiment, one contrivance is made so that the optimum integral value learned in the post-purge can be used in the pre-purge. That is, the object to be stored as the optimum integral value is not the integral value of the correction pulse width Δt (corresponding to the rotational speed deviation NS−N) itself, but the correction pulse width Δt and the set pulse width ts (corresponding to the target rotational speed NS). ) And the integral value of the ratio Δt / tS (corresponding to the deviation / target value ratio). Thus, when the optimal integral value learned in the post-purge is used in the next prepurge, even if the target rotational speed of the prepurge is different from that of the post-purge, the optimal integral value is multiplied by the target rotational speed of the prepurge. That is, in the embodiment, this multiplication is performed by the multiplier 21
1 is performed), it is possible to obtain an integral initial value suitable for the target rotation speed of the prepurge. If the correction pulse width Δ
If the integration result of t itself is to be learned, a conversion process corresponding to the difference in the target rotation speed is separately required to apply the learning result to a different target rotation speed.

According to the above-described device, since the learned optimum integral value can be used in a case where the target value is different, the time for learning the optimum integral value does not necessarily need to be post-purge, and even when combustion is in progress. I do not care. However, during combustion, the sensor output fluctuates and the target rotational speed NS fluctuates in many cases. On the other hand, during the post-purge, there is no such problem and the target rotational speed NS is constant. Is more desirable.

Further, the present embodiment is also useful for smoothly starting hot water supply after lockout due to the control offset. That is, if an offset occurs between the actual rotational speed N and the target rotational speed NS for some reason, the integrated value continues to increase or decrease forever, and eventually reaches a predetermined abnormal value. The hot water supply operation is completely stopped for safety (lockout). In this locked state, the abnormal integral value immediately before the lockout remains in the integral calculating section 225. However, when the hot water supply is performed again thereafter, the abnormal integral value is cleared by step 303 in FIG. Since the integral value is reset, the hot water supply operation can be smoothly restarted.

The contents described above relate to one embodiment of the present invention, and the present invention is not limited to the above contents, but may be modified in various other forms without departing from the gist thereof. It is possible to implement.

For example, in the above embodiment, since the fan motor drive circuit 245 receives a pulse signal and adjusts the motor rotation speed in accordance with the pulse width, the target rotation speed NS and the rotation speed deviation NS-N Is converted to a pulse width, and PI calculation is performed on the pulse width ratio Δt / ts to calculate a coefficient K. On the other hand, as another embodiment, the ratio (N
S−N) / N is directly subjected to a PI operation to obtain a coefficient K, the coefficient K is multiplied by the target rotational speed NS, and the multiplied value NS * K is converted into a pulse width to obtain a fan motor control unit. 2
13 may be input.

In still another embodiment, the correction pulse width Δt (or the rotational speed deviation NS−N) is set to the set pulse width tS.
(Or the target pulse number NS) without dividing by the correction pulse width Δ
PI calculation is directly performed on t, the calculation result is added to the set pulse width ts, and the fan motor control unit 213
When the optimum integral value is learned by post-purge, the optimum integral value is divided by the set pulse width NS and stored in the optimal integral value storage unit 229. Good. Alternatively, at the time of learning in the post-purge, the optimal integral value of the correction pulse width Δt is stored in the optimal integral value storage unit 229 as it is, and when the optimal integral value is used in the pre-purge, the optimal integral value is stored. The target rotation speed ratio NS / NP of the pre-purge and the post-purge may be multiplied.

[0061]

As described above, according to the present invention, the optimum integral value is learned at the time of fan control other than the prepurge, and is used as the integral initial value in the subsequent prepurge. However, the problem that the control sequence of the prepurge is complicated due to the learning by the prepurge as in the related art is solved, and therefore, the effect that the prepurge is completed in a short time and the ignition is quickly achieved is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a combustion device according to one embodiment of the present invention.

FIG. 2 is a flowchart showing a fan control operation of the control system shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Hot water supply burner 103 Intake fan 111 Fan motor 123 Rotation speed sensor 203 Target rotation speed calculation unit 211 Multiplier 213 Fan motor control unit 223 Proportional calculation unit 225 Integral calculation unit 231, 233 Adder

Continuation of the front page (56) References JP-A-1-39281 (JP, A) JP-A-6-2844 (JP, A) JP-A-2-211086 (JP, A) JP-A-4-6346 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F23N 5/20 101 F23N 5/02 350

Claims (4)

(57) [Claims] 1. A control method of a fan motor for supplying air to a combustion device, wherein the value is a value related to a deviation between a target rotation speed and an actual rotation speed of the fan motor, and the rotation speed relative to the target rotation speed. Integral computing means for performing an integral operation on a value corresponding to the ratio of number deviations; proportional computing means for performing a proportional operation on the ratio equivalent value; and an integral value of the ratio equivalent value from the integral computing means and the proportional computing means The feedforward coefficient is calculated by adding the proportionally calculated value from the above and the numerical value 1, and the feedforward coefficient is multiplied by a value corresponding to the target rotational speed, whereby the feedforward control is performed based on the multiplied value. Motor control means for controlling the number of revolutions of the fan motor, which combines the feedback PI control with the fan motor; An optimal integral value storage means for judging whether or not the fan motor rotation speed is in a stable state, and storing an integral value of the ratio equivalent value in the stable state as an optimal integral value; and storing the stored optimal integral value as it is. In the state, as the initial value of the integral value to be used at another fan motor control opportunity different from the predetermined opportunity, an integral initial value setting means to be set in the integral calculating means at the start of the another opportunity. A fan motor control method for a combustion device, comprising: 2. The system according to claim 1, wherein said optimum integral value storage means monitors an integral value of said ratio equivalent value from said integral operation means, and said integral value is substantially continuously constant. A fan motor control method for a combustion device, characterized in that a stable state is determined only at a certain time. 3. The system according to claim 1, wherein the predetermined opportunity is an opportunity for controlling a fan motor other than a pre-purge, and the other opportunity is the prepurge. Fan motor control method. 4. The system according to claim 3, wherein the predetermined opportunity is a post-purge.