JP2526737B2 - Combustor fan motor control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor fan motor control method.

[0002]

2. Description of the Related Art Conventionally, in a combustor such as a gas water heater, feed-forward control for determining an operation amount based on a relationship between a target rotation speed and a plurality of constants and feedback for changing the operation amount based on an actual rotation speed. In combination with the control, the rotation speed of the fan, that is, the rotation speed of the DC fan motor is controlled. In this control method, constants were found experimentally for each model and stored as fixed data in the control device of each combustor, and the constants were not changed.

[0003]

However, in the conventional fan motor control method, the feed forward is caused by the fan motor itself, the DC power source of the fan motor, the variation of the exhaust resistance, or the secular change for each combustor. The control constant sometimes deviated significantly from the proper value. In this case, the target rotation speed is finally controlled by the feedback control, but it takes time for the fan rotation speed to reach the predetermined rotation speed at the time of pre-purging or when the combustion capacity is changed, resulting in ignition. There was a problem that it would be delayed or, in the worst case, it would start safe operation as an abnormality of the fan.

Therefore, the present invention solves the above-mentioned conventional drawbacks,
An object of the present invention is to provide a fan motor control method for a combustor, which prevents a constant in feedforward control from deviating from an appropriate value due to secular change or the like, and can always perform feedforward control in a nearly optimum state.

[0005]

To achieve the above object, the present invention provides a feedforward control for determining an operation amount based on a relationship between a target rotation speed and a plurality of constants, and the operation amount based on an actual rotation speed. In the fan motor control method of the combustor for controlling the rotation speed of the fan in combination with the feedback control for changing, when the time until the rotation speed of the fan reaches the ignition rotation speed during ignition becomes a certain time or more, The first feature is that the constant of the feedforward control is updated again. Further, the present invention controls the rotation speed of a fan by combining feedforward control that determines the operation amount based on the relationship between the target rotation speed and a plurality of constants, and feedback control that changes the operation amount based on the actual rotation speed. In the method of controlling a fan motor of a combustor, the second feature is that the constant of the feedforward control is updated again when the integrated value of the feedback control portion becomes a certain value or more during combustion operation.

[0006]

According to the first feature of the present invention described above, it takes a long time for the number of rotations of the fan to reach the number of rotations required for ignition at the start of combustion operation, and the required ignition rotation is performed even after a certain time has elapsed. When the number is not reached, the feedforward control constant is revised. As a result, the constant is updated to a value according to the current situation, so that the fan rotation speed can be promptly feedforward-controlled again to the specified ignition rotation speed. In addition, the pre-purge time by the fan becomes very long at the start of combustion, which makes it difficult to ignite, and the time until ignition becomes too long, resulting in the device being judged to be abnormal and performing a safe operation. Is eliminated.

Further, according to the second aspect of the present invention, the constant of the feedforward control is revised when the feedback amount to the fan target rotation according to the combustion ability becomes a certain value or more during the combustion operation. As a result, the constant is updated to a value according to the current situation, and thus it becomes possible to perform again the time required for the rotation speed adjustment again in a short time. Further, as a result that the large difference between the target value and the actual value is not easily resolved, the inconvenience that the device determines a fan abnormality and performs a safe operation is resolved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a control device adopting a fan motor control method for a combustor in one embodiment of the present invention, in which a control signal output end 1a of a microcomputer 1 is
It is connected to the input terminal of a conversion circuit 2 that converts an input pulse into a DC voltage corresponding to the pulse width. This conversion circuit 2
Is composed of an inverting amplifier 2a having a hysteresis characteristic, resistors 2b and 2c, capacitors 2d and 2e, and an operational amplifier 2f. The output end of the conversion circuit 2 is connected to the control voltage input end of the power supply circuit 3, and the output end of the power supply circuit 3 is connected to the power supply input end of the fan motor 4 that drives a fan (not shown). Microcomputer 1
The rotation speed signal input end 1b is connected to the output end of a rotation speed sensor 5 which detects the rotation speed of the fan driven by the fan motor 4 and outputs a pulse signal corresponding to the detected rotation speed.

Next, the operation will be described. A pulse signal as shown in FIG. 2 is output from the control signal output terminal 1a of the microcomputer 1. This pulse signal has a constant period T, and the pulse width WPLS changes according to the target rotation speed and the actual rotation speed of the fan. The pulse signal output from the control signal output terminal 1a of the microcomputer 1 is converted into the conversion circuit 2
By this, it is converted into a DC voltage of 0 to 5 V according to the pulse width WPLS and is supplied to the control voltage input terminal of the power supply circuit 3. As a result, the power supply circuit 3 supplies a DC voltage of 0 to 40 V to the fan motor 4 according to the input voltage from the conversion circuit 2. Then, the fan motor 4 rotates at a rotation speed according to the voltage and load supplied by the power supply circuit 3 to drive the fan. The rotation speed of the fan is detected by the rotation speed sensor 5, and is supplied to the rotation speed signal input end 1b of the microcomputer 1 as a pulse signal.

The pulse width WPLS of the pulse signal output from the control signal output end 1a of the microcomputer 1 is
It is calculated by the following formula 1.

[0011]

[Equation 1]

[0012]

That is, in the equation 1, the term determined by the target rotation speed WS and the constants FFA, FFB, FFC is the portion by the feedforward control, and the constants FFA, FF.
The values of B and FFC experimentally obtained for each model are stored in the memory built in the microcomputer 1. Further, the integral term WI is a part under feedback control, and when a difference occurs between the target rotation speed WS and the actual rotation speed NW detected by the rotation speed sensor 5, the microcomputer 1 time-divisions the difference and integrates it. It is accumulated in WI and is controlled so that the actual rotation speed NW matches the target rotation speed WS.
Therefore, if the constants FFA, FFB, FFC deviate significantly from the proper values, the integral term WI becomes large, and it takes too much time for the actual rotation speed NW to match the target rotation speed WS, causing the above-mentioned inconvenience.

Next, the constants FFA and FF which are the subject of the present invention
Regarding the updating of B and FFC, the operation of the microcomputer 1 will be described with reference to FIGS. First of all,
When the operation is started, the time from the start of pre-purge by the fan motor 4 until the fan reaches the ignition rotation speed is measured, and it is determined whether the time is a fixed time, for example, 20 seconds (much longer than the suitability time) or more. Yes (Step 1
1). Then, if the time is equal to or longer than the predetermined time, a constant update request of the feedforward control is requested (step 15). The update request can be made by, for example, turning on the update request flag and storing it in the RAM or the like with a backup power supply built in the microcomputer 1.

If the answer in step 11 is NO, the integral value WI of the feedback control portion is further increased during the combustion operation.
Is greater than or equal to a certain value (step 12), and if greater than or equal to a certain value, it is further determined whether or not it continues for more than a certain time (step 13). Is performed (step 15). If the determinations in steps 11, 12, and 13 are NO, the update request is not issued.

How to actually update the constants of the feedforward control can be carried out, for example, by the constant update routine of FIG. In the routine of FIG.
If there is an update request (step 21), the process proceeds to step 22 and it is determined whether or not there is a combustion request. The process is performed in a state other than the combustion sequence. If there is no combustion request in step 22, the process proceeds to step 23, the target rotation speed WS is set to the prepurge rotation speed, and the fan motor 4 is driven. At this time, feedback control is not performed, the integral term WI is always set to 0, and the rotation speed sensor 5
The control signal output terminal 1a of the microcomputer 1 according to the difference between the actual rotation speed NW and the target rotation speed WS detected by
The pulse width WPLS of the pulse signal output from is appropriately changed.

This is because, if feedback control is performed, if the constants FFA, FFB, FFC are largely deviated from the proper values, it takes too long for the actual rotation speed NW to match the target rotation speed WS, and the above-mentioned This is because such an inconvenience occurs. The initial pulse width WPLS at this time is
It is determined using the constants FFA, FFB, FFC changed at the time of the previous update. If this time is the first update, the initial value set before delivery is used. Next, the routine proceeds to step 24, where it is judged whether or not the actual rotation speed NW is consistent with the target rotation speed WS and is stable, and if it is stable, it proceeds to step 25 where the current target rotation speed WS1 and pulse width are set. The WPLS1 and the WPLS1 are stored in a memory built in the microcomputer 1. Next, the routine proceeds to step 26, where the target rotation speed WS is set near the maximum rotation speed and the fan motor 4 is driven. At this time, similarly to step 23, the feedback control is not performed, the integral term WI is always set to 0, and the rotation speed sensor 5
The control signal output terminal 1a of the microcomputer 1 according to the difference between the actual rotation speed NW and the target rotation speed WS detected by
The pulse width WPLS of the pulse signal output from is appropriately changed. The initial pulse width WPLS at this time is determined using the constants FFA, FFB, FFC changed at the time of the previous update.

If this time is the first update, the initial value set before the delivery is used. Next, the routine proceeds to step 27, where it is judged whether or not the actual rotation speed NW is consistent with the target rotation speed WS and is stable. If it is stable, the routine proceeds to step 28 where the current target rotation speed WS2 and the pulse width are set. The WPLS 2 and the WPLS 2 are stored in a memory built in the microcomputer 1. Next, the routine proceeds to step 29, where the target rotational speeds WS1 and WS2 and the pulse width WPLS stored at steps 25 and 28 are stored.
1, WPLS2 and the optimum values of the constants FFA, FFB, FFC are calculated and stored in the memory built in the microcomputer 1. That is, the target rotation speed WS and the pulse width WPLS have a relationship as shown in FIG. 5, and the constant FFB is 1
If fixed to 00, from the above equation 1, the following equation 2 and equation 3
From this, the constant FFA is obtained from the following equation 4, and the constant FFC is obtained from the following equation 5.

[0019]

[Equation 2]

[0020]

(Equation 3)

[0021]

[Equation 4]

[0022]

(Equation 5)

By executing step 29, the update routine is terminated and the normal routine is returned to. In addition, step 2
If there is no update request in 1, the update routine is terminated and the normal routine is returned to. If there is a combustion request in step 22, the update routine is terminated and the combustion control routine is executed. At this time, the constant FF updated last time
Control is performed using A, FFB, and FFC. If this time is the first update, the initial value set before delivery is used. In the above embodiment, the target rotation speed WS is set to the prepurge rotation speed and near the maximum rotation speed for learning.
This is for more accurately obtaining the optimum values of the constants FFA, FFB, FFC, and it is not always necessary to do so. In addition, the control may be performed based on a calculation formula other than the formula such as Formula 1 above.

[0024]

According to the present invention, there is provided the above construction.
According to the method of controlling the fan motor of the combustor described in (4), when the time until the rotation speed of the fan reaches the ignition rotation speed during ignition becomes a certain time or more, the constant of the feedforward control is updated again. Therefore, even if the constant of the feedforward control does not meet the actual situation, this can be immediately corrected, and the feedforward control of the fan rotation speed to the specified ignition rotation speed can be promptly performed again. In addition, the pre-purge time by the fan becomes very long at the start of combustion, which makes it difficult to ignite, and the time until ignition becomes too long, resulting in the device being judged to be abnormal and performing a safe operation. Is eliminated.

According to the method of controlling a fan motor of a combustor according to a second aspect of the present invention, during the combustion operation, if the feedback amount to the fan target rotation according to the combustion capacity becomes a certain value or more, the constant of the feedforward control is revised. To be As a result, the constant is updated to a value according to the current situation, and thus it becomes possible to perform again the time required for the rotation speed adjustment again in a short time. Further, as a result that the large difference between the target value and the actual value is not easily resolved, the inconvenience that the device determines a fan abnormality and performs a safe operation is resolved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a control device that employs a combustor fan motor control method according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a pulse signal output from a control signal output terminal of a microcomputer.

FIG. 3 is a flowchart illustrating a constant update determination operation by a microcomputer.

FIG. 4 is a flowchart illustrating a constant update operation by a microcomputer.

FIG. 5 is an explanatory diagram of a relationship between a target rotation speed WS of a fan and a pulse width WPLS of a pulse signal output from a control signal output end of a microcomputer.

[Explanation of symbols]

 1 Microcomputer 2 Conversion circuit 3 Power supply circuit 4 Fan motor 5 Rotation speed sensor

Claims (2)

(57) [Claims] 1. A fan rotation speed is controlled by combining a feedforward control that determines an operation amount based on a relationship between a target rotation speed and a plurality of constants and a feedback control that changes the operation amount based on an actual rotation speed. In the method of controlling a fan motor of a combustor, the constant of the feedforward control is updated again when the time until the rotation speed of the fan reaches the ignition rotation speed during ignition becomes a certain time or more. Combustor fan motor control method. 2. A fan rotation speed is controlled by combining a feedforward control that determines an operation amount based on a relationship between a target rotation speed and a plurality of constants and a feedback control that changes the operation amount based on an actual rotation speed. In the method for controlling a fan motor of a combustor, the constant of the feedforward control is updated again when the integrated value of the feedback control portion becomes a certain value or more during combustion operation. Method.