JPH09261988A - Dc motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and quickly realize the control utilizing a drive current and the number of rotations by providing a differential means which differentiates a detection output from a drive current detecting means and then outputs a result to a motor control means and then feeding back a variation rate on the time axis of a drive current of the DC motor to the drive voltage of the DC motor. SOLUTION: A differential, means 24 differentiates a detected output from a drive current detecting means 16 and outputs a result to a motor control means 20 to feed back a variation rate on the time axis of the drive current of a DC motor 5 to a drive voltage of the DC motor 5. Thereby, if a coil current, namely a drive current changes due to change of a drive voltage depending on change of the power supply voltage, its variation rate is immediately fed back to the drive voltage to suppress variation of drive current to a small value. Therefore, the control utilizing drive current and the number of rotations can be realized accurately and quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detecting means for detecting the rotation speed of a DC motor, a drive current detecting means for detecting information about a drive current of the DC motor, and a detection output from the rotation speed detecting means. The present invention relates to a DC motor control device including a motor control unit that controls a drive voltage of a DC motor based on information including a detection output from the drive current detection unit.

[0002]

2. Description of the Related Art Conventional DC motor control devices generally
The rotation speed of the DC motor is detected, the motor control voltage is changed based on the rotation speed, and the drive voltage of the DC motor is controlled according to the motor control voltage.

By the way, the state equation in the operating state of the DC motor is represented by the following equations 1 and 2, and a block diagram is drawn by obtaining a transfer function from these equations, as shown in FIG. Here, L is the inductance of the winding, R is the resistance of the winding, J is the inertia coefficient of the rotor, B is the viscosity coefficient of the rotor and shaft, K _T is the torque constant, K _e is the back electromotive force constant, and T _L is Disturbance torque, V is a drive voltage, I is a current flowing through the winding, that is, a drive current, and N is a rotation speed.

[0004]

[Equation 1]

[0005]

[Equation 2]

As can be seen from the equations (1) and (2) and FIG. 15, the driving voltage V is changed by the fluctuation of the power source voltage.
Change, the drive current I changes at a predetermined response speed, the change in the drive current I changes the rotation speed N at a predetermined response speed, and the change in the rotation speed N is fed back to the drive voltage V. Thus, it acts so as to prevent changes in the drive current I and the rotation speed N due to changes in the drive voltage V.

Therefore, the change in the drive current I and the rotation speed N due to the change in the drive voltage V is large, and the time required for them to return from the transient state to the steady state is long.

Therefore, as a control method of such a DC motor, the rotation speed N is detected, the motor control voltage V _S is changed based on the detected speed N, and the motor is driven according to the motor control voltage V _S , as in the prior art. When a control method such as controlling the voltage V is adopted, for example, as shown in FIG. 16, a change in the drive voltage V causes a large change in the drive current I and the rotational speed N, and moreover, the time until the steady state is restored. Is also long. Further, even in the steady state, the driving voltage V always fluctuates slightly, but the fluctuation of the driving current I due to the fluctuation is relatively large.

[0009]

From the above, in the conventional DC motor control device described above, the drive current I and the rotation speed N are set.
However, there is a problem that the control using cannot be performed accurately. For example, a DC motor is used to drive the fan of the combustor, the flow resistance of the blast flow passage is calculated from the drive current I and the rotation speed N, and the optimum rotation according to the flow resistance and the combustion amount is calculated. When the fan is rotated by a certain number, it is necessary to calculate the flow path resistance by a numerical value in the steady state of the driving current I and the number of rotations N. Therefore, the driving voltage V fluctuates due to fluctuations in the power supply voltage, etc. When I and the rotational speed N are in a transient state, the flow path resistance cannot be accurately calculated. Moreover, if the changes in the drive current I and the rotation speed N are large, the calculation result of the flow path resistance may deviate greatly from the actual value, and the amount of air blown may become inadequate, which may adversely affect combustion.

Further, since the driving current I constantly fluctuates due to a small fluctuation of the driving voltage V, it is necessary to increase the time constant of the circuit after the detection circuit in order to detect the driving current I.
For this reason, there is also a problem that the detection time delay is large.

The present invention has been proposed in view of the above points, and an object thereof is to provide a DC motor control device that can accurately and quickly perform control using a drive current and a rotation speed.

[0012]

Means for Solving the Problems To solve the above problems, the present invention takes the following technical means.

That is, the invention described in claim 1 of the present application comprises a rotation speed detecting means for detecting the rotation speed of the DC motor,
Motor control for controlling the drive voltage of the DC motor on the basis of information including drive current detection means for detecting information on the drive current of the DC motor, and detection output from the rotation speed detection means and detection output from the drive current detection means A DC motor control device comprising: means for driving the DC motor to change the temporal change rate of the drive current of the DC motor by differentiating the detection output from the drive current detecting means and outputting the differentiated output to the motor control means. It is characterized in that a differentiating means for feeding back the voltage is provided.

According to this DC motor control device, the differentiating means differentiates the detection output from the drive current detecting means and outputs the differentiated output to the motor control means, so that the temporal change rate of the drive current of the DC motor is controlled by the direct current. Since it is fed back to the drive voltage of the motor, if the drive voltage changes due to fluctuations in the power supply voltage and the winding current, that is, the drive current changes, the rate of change is immediately returned to the drive voltage. It can be kept small. Therefore, the control using the drive current and the rotation speed can be accurately and quickly performed. further,
Since it is possible to almost eliminate fluctuations in the drive current due to slight fluctuations in the power supply voltage, it is not necessary to increase the time constant of the circuits after the detection circuit to detect the drive current. The delay can be reduced.

The DC motor may be any motor that can be driven by DC power, such as a three-phase brushless motor.
The type does not matter. The rotation speed detecting means can be configured by, for example, a hall element incorporated in the DC motor, but is not limited to this, and for example, a rotary encoder or the like may be used. The drive current detection means can be configured by, for example, a non-contact type galvanometer, but is not limited to this. The motor control means can be constituted by, for example, a variable voltage type switching regulator or the like, but is not limited to this, and may be one which varies the drive voltage by the PWM method. As the differentiating means, for example, a differentiating circuit using an operational amplifier can be used. The output of the differentiating means may be combined with the motor control voltage for controlling the drive voltage or may be directly combined with the drive voltage.

The invention described in claim 2 of the present application is
A DC motor control device for rotating a DC motor by supplying power to a DC motor for rotating a blower fan arranged in a blower flow path of a combustor. Optimal air flow rate determination means for determining, rotation speed detection means for detecting the rotation speed of the DC motor, drive current detection means for detecting information about the drive current of the DC motor, detection output from the drive current detection means and rotation speed A flow path resistance determination unit that determines the flow path resistance of the air flow path based on the detection output from the detection unit, and the optimum air flow rate determined by the optimum air flow rate determination unit and the flow rate determined by the flow path resistance determination unit. Optimum rotation speed discriminating means for discriminating the optimum rotation speed of the DC motor based on the road resistance, and driving of the DC motor based on the discrimination result by the optimum rotation speed discriminating means and the detection output from the rotation speed detecting means. The detection output from the motor control means for controlling the pressure and the drive current detection means is differentiated and output to the motor control means to feed back the temporal change rate of the drive current of the DC motor to the drive voltage of the DC motor. Differentiating means is provided.

According to this DC motor control device, in addition to the effect of the DC motor control device according to the first aspect, the optimum rotation speed discriminating means causes the optimum air flow rate according to the combustion amount and the flow path resistance of the air flow path. The optimum rotation speed of the DC motor is determined based on the above, and the DC motor is driven by the motor control unit so that the rotation speed becomes the optimum rotation speed. Can be maintained. Therefore, even if the flow path resistance changes, optimum combustion can always be maintained.

The invention described in claim 3 of the present application is
A DC motor control device for rotating a DC motor by supplying power to a DC motor for rotating a blower fan arranged in a blower flow path of a combustor. Optimal air flow rate determination means for determining, rotation speed detection means for detecting the rotation speed of the DC motor, drive current detection means for detecting information about the drive current of the DC motor, detection output from the drive current detection means and rotation speed The flow path resistance determining means for determining the flow path resistance of the air flow path based on the detection output from the detecting means, and the flow path resistance determined by the flow path resistance determining means and the detection output from the rotation speed detecting means. Based on the deviation between the optimum air flow rate estimation means for estimating the actual air flow rate based on the actual air flow rate based on the deviation between the optimum air flow rate determined by the optimum air flow rate determination means and the actual air flow rate estimated by the air flow rate estimation means. Optimum rotation speed determination means for determining the rotation speed, motor control means for controlling the drive voltage of the DC motor based on the determination result by the optimum rotation speed determination means and the detection output from the rotation speed detection means, and drive current detection means Differentiating means is provided for feeding back the temporal change rate of the drive current of the DC motor to the drive voltage of the DC motor by differentiating the detected output from the motor control means.

According to this DC motor control device, in addition to the effect of the DC motor control device according to the first aspect, the actual rotation amount estimated to be the optimum ventilation amount according to the combustion amount by the optimum rotation speed determination means. Since the optimum rotation speed of the DC motor is determined based on the deviation between and, and the DC motor is driven by the motor control means so that the optimum rotation speed is achieved, install an air volume detection means such as a wind speed sensor in the air flow passage. Instead, the DC motor can be appropriately controlled by estimating the actual air flow rate.
Therefore, even if the flow path resistance or the like changes, optimum combustion can always be maintained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a hot water supply apparatus including a DC motor control device according to the present invention. A burner 2 and a heat exchanger 3 are arranged inside a casing 1 of the hot water supply apparatus. . A sirocco fan 6 driven by a DC motor 5 is installed inside a fan case 4 continuous with the casing 1, and an exhaust port 7 is formed in the upper portion of the casing 1. A fuel supply pipe 8 for supplying fuel such as gas or oil is connected to the burner 2, and a water supply pipe 1 for supplying water to the heat exchanger 3.
0 is connected. Valves 11 and 12 are provided in the fuel supply pipe 8 and the water supply pipe 10, respectively.
1, 12 are controlled by the hot water supply controller 13.

The DC motor control device includes a rotation speed detection means 15 for detecting the rotation speed of the DC motor 5 based on the rotation pulse from the DC motor 5, and a drive current detection means for detecting information about the drive current of the DC motor 5. 16, and the flow path resistance determination for determining the flow path resistance of the air flow path in the casing 1 and the fan case 4 based on the detection value from the drive current detection means 16 and the rotation speed detected by the rotation speed detection means 15. The optimum air flow rate determination means 18 for determining the optimum air flow rate based on the signal corresponding to the combustion amount of the burner 2, that is, the fuel supply amount from the hot water supply control unit 13, and the optimum air flow rate determination means 18 are used for the determination. Optimal rotation speed determination means 19 for determining the optimum rotation speed of the DC motor 5 based on the optimum air flow rate and the flow path resistance determined by the flow path resistance determination means 17.
And a motor control unit 20 that drives the DC motor 5 so that the optimum rotation speed determined by the optimum rotation speed determination unit 19 and the flow path resistance determined by the flow path resistance determination unit 17 are detected. Abnormality determining means 21 for determining
And an abnormality processing unit 22 that outputs a stop signal to the hot water supply control unit 13 to stop the combustion of the burner 2 when the abnormality determination unit 21 determines that the combustion is abnormal, and a detection output from the drive current detection unit 16. Differentiating means 24 is provided for feeding back the temporal change rate of the drive current of the DC motor 5 to the drive voltage of the DC motor 5 by differentiating and outputting to the motor control means 20. The flow path resistance discriminating means 17, the optimum air flow rate discriminating means 18, the optimum rotational speed discriminating means 19, the abnormality discriminating means 21 and the abnormality processing means 22 are realized by a microcomputer 23.

FIG. 2 is a circuit diagram of the DC motor 5. The DC motor 5 includes a plurality of Hall elements 25, switching control means 26, terminals 27a to 27e, drive coils U, V and W, and transistors. Q1 to Q16, diodes D1 to D6, resistors R1 to R29, and a capacitor C
1 is provided. The switching control means 26 including an IC turns on / off the transistors Q1 to Q6 based on the detection signal from the hall element 25 to perform switching control. The DC voltage VCC is input to the terminal 27a,
It is supplied to the switching control means 26 and the like. Terminal 27
b is grounded. From the terminal 27c, a rotation pulse VFG corresponding to the rotation speed of the DC motor 5 is output from the switching control means 26 via the transistor Q16. A drive voltage VDC is applied to the terminal 27d and supplied to the drive coils U, V, W. The rotation speed of the DC motor 5 is determined by the drive voltage VDC applied to the terminal 27d. A drive current flowing through the drive coils U, V, W is output from the terminal 27e. Since the circuit configuration of the DC motor 5 is well known, a detailed description of the connection state will be omitted.

FIG. 3 is a circuit diagram of the driving current detecting means 16. The driving current detecting means 16 is built in the DC motor 5, and has an input terminal 29, an output terminal 30, a current transformer CT1. Operational amplifiers OP1 and OP2,
Variable resistors VR1 and VR2, and resistors R30 to R35
And capacitors C2 and C3. Input terminal 2
9 is grounded via the current transformer CT1 and is also connected to the terminal 27e of the DC motor 5.
That is, the drive current flowing through the drive coils U, V, W of the DC motor 5 returns to the power source through the current transformer CT1. A resistor R3 is provided at the output terminal of the current transformer CT1.
0 is connected, and one end of this resistor R30 is grounded. The other end of the resistor R30 is connected to the non-inverting input terminal of the operational amplifier OP1. The inverting input terminal of the operational amplifier OP1 is grounded via the resistor R31, and the resistor R3 is provided between the output terminal and the inverting input terminal of the operational amplifier OP1.
2 and the capacitor C2 are connected in parallel. The output terminal of the operational amplifier OP1 is connected to the inverting input terminal of the operational amplifier OP2 via the resistor R34, and the DC voltage V
A resistor R33 and a variable resistor VR1 are provided between CC and ground.
A series circuit with is interposed. The slider of the variable resistor VR1 is connected to the non-inverting input terminal of the operational amplifier OP2, and the output terminal of the operational amplifier OP2 is connected to the output terminal 30 and one end of the variable resistor VR2. Variable resistor VR
The other end of 2 is connected to the inverting input end of the operational amplifier OP2 through the parallel circuit of the resistor R35 and the capacitor C3.

FIG. 4 is a circuit diagram of the differentiating means 24. One end of the resistor R36 is the output terminal 3 of the drive current detecting means 16.
0, and the other end of the resistor R36 is connected to one end of the capacitor C4. The other end of the capacitor C4 is connected to the inverting input end of the operational amplifier OP3 and one end of the resistor R37. The other end of the resistor R37 has an output terminal 3
1 and the output terminal of the operational amplifier OP3.
The non-inverting input terminal of the operational amplifier OP is grounded. Since this differentiating circuit is well known, detailed description of its operation is omitted.

FIG. 5 is a circuit block diagram of the motor control means 20. This motor control means 20 is a rectifier circuit 3
2, switching regulator 33, control voltage generator 3
4 and a capacitor C5. Rectifier circuit 32
Full-wave rectifies the electric power of the commercial power supply 35. The switching regulator 33 switches the DC power smoothed by the capacitor C5 and outputs a DC voltage corresponding to the motor control voltage from the control voltage generator 34 as the drive voltage VDC by the PAM method. Control voltage generator 34
Generates a control voltage based on the optimum rotation speed from the optimum rotation speed determination means 19 and the rotation speed from the rotation speed detection means 15, and further subtracts the output of the differentiating means 24 from the control voltage to obtain the motor control voltage. Switching regulator 3
It outputs to the voltage control terminal of 3.

The output of the control voltage generator 34 is a resistor R.
38 to R42 and an operational amplifier OP4. A control voltage corresponding to the deviation between the optimum rotation speed from the optimum rotation speed determination means 19 and the rotation speed from the rotation speed detection means 15 is input to one end of the resistor R38. The other end of the resistor R38 is connected to one end of the resistors R39 and R40 and the non-inverting input end of the operational amplifier OP4, and the other end of the resistor R39 is connected to the output terminal 31 of the differentiating means 24. The inverting input terminal of the operational amplifier OP is connected to one end of the resistors R41 and 42, and the other ends of the resistors R40 and R41 are grounded. The other end of the resistor R42 is connected to the output end of the operational amplifier OP4 and the voltage control end of the switching regulator 33. Therefore, the motor control voltage obtained by subtracting the output of the differentiating means 24 from the control voltage is output from the operational amplifier OP4 to the voltage control terminal of the switching regulator 33.

Next, the operation of the water heater will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG. When an operation command is input to the controller from a remote controller (not shown), the hot water supply control unit 13 controls the valves 11 and 12 and an igniter (not shown) to start the ignition operation, and to the optimum blown air amount determination means 18. A signal corresponding to the combustion amount of the burner 2, that is, the valve opening amount of the valve 11 is output. As a result, the optimum air flow rate determination unit 18 calculates the optimum air flow rate according to the combustion amount of the burner 2 based on the signal from the hot water supply control unit 13 (S1).

At this time, the DC motor 5 is not rotating, and the determination result by the flow path resistance determining means 17 is not supplied to the optimum rotation speed determining means 19, so the optimum rotation speed determining means 19 is set in advance, for example. A signal corresponding to the initial rotation speed of about 3000 rpm is output to the motor control means 20 (S2). As a result, the motor control means 20 causes the DC motor 5 to drive the drive voltage VDC so as to rotate at the initial rotation speed.
Is supplied to drive the DC motor 5.

Next, the abnormality determining means 21 activates the built-in timer (S3). Specifically, a register built in the CPU of the microcomputer 23 is used as a down counter, a predetermined value is set in the down counter by a program, and the contents of the down counter are decremented by 1 by a clock signal of a predetermined cycle. To go.

Next, the drive current detecting means 16 detects the drive current of the DC motor 5 (S4). That is, the drive current flowing through the drive coils U, V, W of the DC motor 5 flows from the terminal 27e of the DC motor 5 into the input terminal 29 of the drive current detecting means 16 as shown in FIG. Return to power through. Therefore, a voltage corresponding to the drive current of the DC motor 5 is induced in the current transformer CT1, which is applied to the resistor R30 and input to the non-inverting input terminal of the operational amplifier OP1. Operational amplifier OP
1 is a resistor R31, which converts the voltage input to the non-inverting input terminal,
It is amplified by the amplification factor determined by R32 and supplied to the inverting input terminal of the operational amplifier OP2 via the resistor R34. As a result, the operational amplifier OP2 amplifies the difference voltage between the voltage input to the non-inverting input terminal of the operational amplifier OP2 and the output voltage of the operational amplifier OP1 with an amplification factor determined by the variable resistor VR2 and the resistors R34 and R35. Then, the detected voltage E is output to the output terminal 30. This detection voltage E is supplied to the flow path resistance determining means 17.

Here, the voltage input to the non-inverting input terminal of the operational amplifier OP2 is changed by moving the slider of the variable resistor VR1. That is, the variable resistor VR
When the slider 1 is moved, the difference voltage between the operational amplifier OP2 and the output voltage of the operational amplifier OP1 changes, so that the drive current flowing through the current transformer CT1 and the detection voltage E appearing at the output terminal 14 are changed. Relationship changes. Therefore, as shown in FIG. 7, the relationship between the rotation speed N of the DC motor 5 and the detection voltage E appearing at the output terminal 30 is as follows.
By moving the slider of the variable resistor VR1, for example, the level is shifted from the solid line state to the broken line state. As a result, if there are variations in the characteristic levels of the rotation speed and drive current of each DC motor 5 during manufacturing, the detection characteristics can be adjusted in advance by adjusting them with the variable resistor VR1.

Further, when the slider of the variable resistor VR2 is moved, the resistance value of the variable resistor VR2 changes, so that the feedback factor changes and the amplification factor of the operational amplifier OP2 also changes. The relationship between the drive current flowing through CT1 and the detection voltage E appearing at the output terminal 30 changes. Therefore, as shown in FIG.
The relationship between the detected voltage E appearing at the output terminal 30 and the detection voltage E appearing at the output terminal 30 changes from the solid line state to the broken line state by moving the slider of the variable resistor VR2. As a result, when there is a variation in the slope of the characteristics of the rotation speed and drive current of each DC motor 5 during manufacturing, the variable resistor VR2 can be used to adjust the detection characteristics in advance.

Next, the rotation speed detecting means 15 detects the rotation speed of the DC motor 5 based on the rotation pulse from the hall element 25 of the DC motor 5 (S5).

Next, the flow path resistance discriminating means 17 causes the inside of the fan case 4 and the casing 1 based on the detected voltage E from the drive current detecting means 16 and the signal corresponding to the rotational speed from the rotational speed detecting means 15. The flow path resistance Φ of the air flow path is determined (S6). That is, since the relationship between the rotation speed N of the DC motor 5 and the drive current I changes according to the flow path resistance Φ, as shown in FIG. 9, the rotation speed N, the drive current I, and the flow path resistance Φ. By storing the related data in a memory or the like in advance, the flow path resistance Φ can be determined from the rotation speed N and the drive current I. For example, when the rotation speed N is N1, the drive current I
Becomes I0 or the drive current I becomes I1 when the rotation speed N is N2, it can be determined that the flow path resistance Φ is Φ1, and the drive current I becomes I0 when the rotation speed N is N0. Therefore, it can be determined that the flow path resistance Φ is Φ0. Φ0
Is smaller than Φ1. Further, the flow path resistance Φ can be experimentally obtained by the following mathematical formula 3, where N is the number of rotations of the DC motor 5 and I is the drive current. However, g
(N) and f (N) are functions of the rotation speed N. Or,
As another empirical formula, it is determined by the following formula 4.

[0036]

(Equation 3)

[0037]

(Equation 4)

Next, the abnormality determining means 21 determines whether the flow path resistance Φ determined by the flow path resistance determining means 17 is between a predetermined lower limit value ΦL and upper limit value ΦH. Yes (S7). That is, the flow path resistance Φ is the lower limit value ΦL.
The area deviating from between the upper limit value ΦH and the upper limit value ΦH is shown by diagonal lines in FIG. 10. When the flow path resistance Φ reaches such a value,
Even if the rotation speed N of the DC motor 5 is controlled, an appropriate air flow cannot be secured, so it is necessary to judge that it is in an abnormal state, and if the flow path resistance Φ is between the lower limit value ΦL and the upper limit value ΦH. By controlling the number of rotations of the DC motor 5, it is possible to secure an appropriate air flow rate, and thus it can be determined that the state is normal. The first quadrant of FIG. 10 is the rotation speed N of the DC motor 5.
Represents the relationship between the drive current I and the flow path resistance Φ.
The quadrant is the rotation speed N of the DC motor 5, the air flow rate Q, and the flow path resistance Φ.
Represents the relationship with

The abnormality determining means 21 determines that the flow path resistance Φ is between the lower limit value ΦL and the upper limit value ΦH (S7: YE).
S), it is determined to be normal, and the built-in timer is cleared (S8). As soon as this timer is cleared, it restarts and resumes timing operation.

Next, the optimum rotational speed discriminating means 19 determines the optimum rotational speed based on the flow path resistance Φ discriminated by the flow channel resistance discriminating means 17 and the optimum air flow rate discriminated by the optimum air flow rate discriminating means 18. Is calculated (S9). That is, as shown in FIG. 9, the relationship between the rotation speed N of the DC motor 5 and the air flow rate Q changes depending on the flow path resistance Φ, so that the optimum rotation speed is obtained according to the flow path resistance Φ so as to obtain the optimum air flow rate. Determine the number. The optimum rotation speed Ns is obtained by, for example, an empirical formula of the following Expression 5, assuming that the optimum air blowing amount is Q0 and the reference rotation speed determined based on the reference flow path resistance Φ0 and the combustion amount is Ng. Alternatively, as another empirical formula, it can also be obtained by the following mathematical formula 6.

[0041]

(Equation 5)

[0042]

(Equation 6)

Further, the optimum rotation speed discrimination means 19 outputs the calculated optimum rotation speed to the motor control means 20 (S1).
0).

As a result, the motor control means 20 causes the DC motor 5 to reach the optimum rotation speed based on the optimum rotation speed from the optimum rotation speed determination means 19 and the actual rotation speed from the rotation speed detection means 15. Then, the DC motor 5 is driven.

Next, the optimum air flow rate determination means 18 determines whether or not the combustion amount is changed based on the signal from the hot water supply controller 13 (S11), and if there is no change (S11: N).
O), the microcomputer 23 determines whether or not an operation end instruction is input from the remote controller (S12), and if not input (S12: NO),
Return to S5. If it has been input (S12: YES), the routine ends.

In S11, the optimum air flow rate determination means 18
Determines that the combustion amount has changed (S11: YE
S), returning to S1.

In S7, if the abnormality determining means 21 determines that the flow path resistance Φ is not between the predetermined lower limit value ΦL and the upper limit value ΦH (S7: NO), the abnormality determining means further proceeds. 21 determines whether or not the built-in timer is up (S13), and if not (S13: NO), the process proceeds to S9. If the time is up (S13: YES), the fact that there is an abnormality is output to the abnormality processing means 22. That is, since the flow path resistance Φ may constantly change due to the influence of wind, etc., the flow path resistance Φ
Only when the value becomes an abnormal value over a predetermined time, it is judged as an abnormal state.

Next, when the abnormality processing means 22 receives the signal indicating the abnormality from the abnormality determining means 21, it outputs an abnormality signal to the hot water supply control section 13 to stop the combustion of the burner 2 and the like. The abnormality process is performed (S14), and the routine ends.

When the drive voltage VDC of the DC motor 5 changes due to the voltage fluctuation of the commercial power supply 35, the winding current of the DC motor 5, that is, the drive current I changes. The drive current I is converted into a voltage by the drive current detecting means 16 and differentiated by the differentiating means 24, and the motor control means 2
0 is supplied. That is, the temporal change rate of the drive current I is input to the motor control means 20, and the control voltage generator 3 is supplied.
4, the optimum rotation speed N from the optimum rotation speed determination means 19
is subtracted from the control voltage generated based on s and the rotation speed N from the rotation speed detection means 15, and the subtracted voltage is used as the motor control voltage V _S in the switching regulator 3
3 is output to the voltage control terminal. Therefore, the output voltage of the switching regulator 33, that is, the drive voltage VDC of the DC motor 5 is immediately corrected by feeding back the rate of change of the drive current I of the DC motor 5, and the drive current I of the DC motor 5 and the rotational speed N are corrected. Changes are quickly suppressed.

That is, the block diagram of the DC motor 5 and the differentiating means 24 is equivalently as shown in FIG.
When the rectified / smoothed voltage V input to the switching regulator 33 of the motor control means 20 fluctuates, the motor control voltage V _S , the drive current I, and the rotation speed N change as shown in FIG. As is clear from FIG. 12, FIG.
Compared with the conventional case shown in FIG. 6, changes in the drive current I and the rotation speed N due to fluctuations in the rectification / smoothing voltage V are very small. Moreover, the drive current I hardly changes with a steady slight fluctuation of the rectification / smoothing voltage V. This is because when the rectified / smoothed voltage V falls, the drive voltage VDC
There was lowered, the drive current I also begins to decrease, but because the differential value is subtracted from the motor control voltage V _S, the motor control voltage V _S rises sharply, and as a result, the driving voltage VDC
Is increased, so that the change in the drive current I is suppressed. Conversely, when the rectified and smoothed voltage V rises, the drive voltage VDC is increased, the driving current I also begins to increase, but since the differential value is subtracted from the motor control voltage V _S, rapid motor control voltage V _S is , And as a result, the drive voltage VDC decreases, so that the change of the drive current I is suppressed. In FIG. 11, β is a constant that determines the feedback gain of the differential value of the drive current I.

FIG. 13 is a schematic configuration diagram of a hot water supply device including a DC motor control device according to another embodiment.
The difference from the water heater shown in FIG.
As a component realized by 3, the air flow rate estimation unit 41 that estimates the actual air flow rate based on the flow channel resistance determined by the flow channel resistance determination unit 17 and the rotation speed detected by the rotation speed detection unit 15. And a target rotation speed discriminating means 42 for discriminating the target rotation speed of the DC motor 5 based on the combustion amount of the burner 2. Therefore, the optimum rotation speed determination means 19 determines by the target rotation speed determination means 42 the deviation between the optimum air flow rate determined by the optimum air flow rate determination means 18 and the actual air flow rate estimated by the air flow rate estimation means 41. The optimum rotation speed of the DC motor 5 is determined based on the determined target rotation speed. Further, the abnormality determining means 21 determines the combustion abnormality based on the actual air flow rate estimated by the air flow rate estimating means 41. Other configurations are similar to those of the hot water supply device according to the first embodiment shown in FIG.

Next, the operation of the water heater will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG. When an operation command is input to the controller from a remote controller (not shown), the hot water supply control unit 13 controls the valves 11 and 12 and an igniter (not shown) to start the ignition operation, and to the optimum blown air amount determination means 18. A signal corresponding to the combustion amount of the burner 2, that is, the valve opening amount of the valve 11 is output. As a result, the optimum air flow rate determination means 18 calculates the optimum air flow rate according to the combustion amount of the burner 2 based on the signal from the hot water supply controller 13 (S21).

Next, the target rotation speed discriminating means 42 calculates the target rotation speed for obtaining the optimum air blowing amount according to the combustion amount of the burner 2 based on the signal from the hot water supply control unit 13 (S22). .

At this time, the DC motor 5 is not rotating and the determination result by the flow path resistance determining means 17 is not supplied to the optimum rotation speed determining means 19, so the optimum rotation speed determining means 19 is set in advance, for example. A signal corresponding to the initial rotation speed of about 3000 rpm is output to the motor control means 20 (S23). As a result, the motor control means 20 causes the DC motor 5 to drive the drive voltage VD so that the motor control means 20 rotates at the initial rotation speed.
C is supplied to drive the DC motor 5.

Next, the abnormality determining means 21 activates the built-in timer (S24).

Next, the drive current detecting means 16 detects the drive current of the DC motor 5 (S25).

Next, the rotation speed detecting means 15 detects the rotation speed of the DC motor 5 based on the rotation pulse from the hall element 25 of the DC motor 5 (S26).

Next, the flow path resistance judging means 17 determines the fan case 4 and the casing 1 based on the detected voltage E from the drive current detecting means 16 and the signal corresponding to the rotation speed N from the rotation speed detecting means 15. The flow path resistance Φ of the internal air flow path is determined (S27).

Next, the blown air amount estimation means 41 actually determines based on the flow path resistance Φ determined by the flow path resistance determination means 17 and the rotation speed N of the DC motor 5 detected by the rotation speed detection means 15. The air flow rate Q is calculated (S28). That is, as shown in FIG. 9, the actual rotation speed N of the DC motor 5
The relationship between the air flow rate Q and the actual air flow rate Q changes depending on the change in the flow path resistance Φ of the air flow path, but once the flow path resistance Φ is determined, it is uniquely determined accordingly, so the rotational speed N and the flow path resistance Φ By obtaining the relationship with the air flow rate Q and storing it in the memory in advance, the actual air flow rate Q can be calculated from the rotation speed N of the DC motor 5 and the flow path resistance Φ.

Next, the abnormality determining means 21 determines whether or not the air flow rate Q estimated by the air flow rate estimating means 41 is between a predetermined lower limit value QL and upper limit value QH ( S29).

The abnormality determining means 21 determines that the air flow rate Q is the lower limit value Q.
If it is between L and the upper limit value QH (S29: YE
S), it is determined to be normal, and the built-in timer is cleared (S30). As soon as this timer is cleared, it restarts and resumes timing operation.

Next, the optimum rotational speed discriminating means 19 determines, based on the deviation between the actual air blowing amount Q1 estimated by the air blowing amount estimating means 41 and the optimum air blowing amount Q0 discriminated by the optimum air blowing amount discriminating means 18. The optimum rotation speed N1 is calculated by the following formula 7 (S31). That is, the sum of the proportional component and the integral component of the deviation between the optimum air flow rate Q0 and the estimated actual air flow rate Q1 is added to the target rotational speed N0 as a feedback component. Accordingly, if the deviation between the optimum air flow rate Q0 and the estimated actual air flow rate Q1 is stable in the state of zero,
The target rotation speed N0 becomes the optimum rotation speed N1. In the following mathematical formula 7, Kp and Ki are predetermined constants.

[0063]

(Equation 7)

Further, the optimum rotation speed discrimination means 19 outputs the calculated optimum rotation speed to the motor control means 20 (S3).
2).

As a result, the motor control means 20 causes the DC motor 5 to reach the optimum rotation speed based on the optimum rotation speed from the optimum rotation speed determination means 19 and the actual rotation speed from the rotation speed detection means 15. Then, the DC motor 5 is driven.

Next, the optimum blown air amount judging means 18 judges based on the signal from the hot water supply controller 13 whether or not the combustion amount has changed (S33), and if there is no change (S33: N).
O), the microcomputer 23 determines whether or not an operation end instruction is input from the remote controller (S34), and if not input (S34: NO),
Return to S25. If it has been input (S34: YES),
End the routine.

In S33, the optimum air flow rate determination means 18
Determines that the combustion amount has changed (S33: YE
S) and returns to S21.

In S29, if the abnormality determining means 21 determines that the blown air amount Q is not between the predetermined lower limit value QL and the upper limit value QH (S29: NO), the abnormality determining means 21 It is determined whether or not the built-in timer has timed out (S35), and if not (S35: NO), the process proceeds to S31. If the time is up (S35: YES), the fact that there is an abnormality is output to the abnormality processing means 22. That is, since the blown air amount Q may constantly change due to the influence of wind or the like, the air blown amount Q is determined to be in an abnormal state only when the blown air amount Q becomes an abnormal value for a predetermined time or longer.

Next, the abnormality processing means 22 is used as the abnormality determining means 2
By inputting the signal from 1 that there is an abnormality,
An abnormality signal is output to the hot water supply control unit 13 to perform abnormality processing such as stopping the combustion of the burner 2 (S36), and the routine ends.

As a matter of course, the variation suppressing operation of the drive current I and the rotation speed N of the DC motor 5 by the differentiating means 24 is as shown in FIG.
This is similar to the case of the hot water supply device shown in.

[0071]

As described above, according to the first aspect of the invention, the differentiating means differentiates the detection output from the drive current detecting means and outputs the differentiated output to the motor control means. Since the rate of change over time is fed back to the drive voltage of the DC motor, if the drive voltage changes due to fluctuations in the power supply voltage and the winding current, that is, the drive current changes, that rate of change is immediately fed back to the drive voltage. Therefore, the change in drive current can be suppressed to a small level. Therefore, the control using the drive current and the rotation speed can be accurately and quickly performed. Furthermore, since it is possible to almost eliminate fluctuations in the drive current due to slight fluctuations in the power supply voltage, it is not necessary to increase the time constant of the circuits after the detection circuit to detect the drive current. The time delay can be reduced.

According to the invention of claim 2, claim 1
In addition to the effect of the DC motor control device described, the optimum rotation speed determination means determines the optimum rotation speed of the DC motor based on the optimum air flow rate according to the combustion amount and the flow path resistance of the air flow path. Since the DC motor is driven by the control means so as to attain the optimum rotation speed, it is possible to always maintain an appropriate motor rotation speed according to the flow resistance of the air flow passage. Therefore, even if the flow path resistance changes, optimum combustion can always be maintained.

According to the invention of claim 3, claim 1
In addition to the effect of the DC motor control device described, the optimum rotation speed determination means determines the optimum rotation speed of the DC motor based on the deviation between the optimum air flow rate according to the combustion amount and the estimated actual air flow rate. Since the motor control means drives the DC motor so as to achieve the optimum rotation speed, it is possible to properly estimate the DC air volume by estimating the actual air flow volume without installing air volume detection means such as an air velocity sensor in the air flow passage. You can control. Therefore, even if the flow path resistance or the like changes, optimum combustion can always be maintained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hot water supply device including a DC motor control device according to the present invention.

FIG. 2 is a circuit diagram of a DC motor controlled by a DC motor control device according to the present invention.

FIG. 3 is a circuit diagram of drive current detection means provided in the DC motor control device according to the present invention.

FIG. 4 is a circuit diagram of a differentiating means provided in the DC motor control device according to the present invention.

FIG. 5 is a circuit block diagram of motor control means provided in the DC motor control device according to the present invention.

FIG. 6 is a flowchart illustrating an operation of the DC motor control device according to the present invention.

FIG. 7 is an explanatory diagram of the relationship between the detected voltage by the drive current detection means provided in the DC motor control device according to the present invention and the rotation speed of the DC motor.

FIG. 8 is an explanatory diagram of the relationship between the detected voltage by the drive current detection means provided in the DC motor control device according to the present invention and the rotation speed of the DC motor.

FIG. 9 is an explanatory diagram of the relationship between the drive current, the rotation speed, and the air flow rate of the DC motor controlled by the DC motor control device according to the present invention.

FIG. 10 is an explanatory diagram of an abnormality determination area by abnormality determination means provided in the DC motor control device according to the present invention.

FIG. 11 is an equivalent block diagram of a differentiating means and a DC motor provided in the DC motor control device according to the present invention.

FIG. 12 is a signal waveform diagram of each part of the DC motor control device according to the present invention.

FIG. 13 is a schematic configuration diagram of a hot water supply device including a DC motor control device according to another embodiment.

FIG. 14 is a flowchart illustrating an operation of a DC motor control device according to another embodiment.

FIG. 15 is an equivalent block diagram of a DC motor.

FIG. 16 is a signal waveform diagram of each part of the conventional DC motor control device.

[Explanation of symbols]

 2 burner 5 DC motor 6 sirocco fan 15 rotation speed detection means 16 drive current detection means 17 flow path resistance determination means 18 optimum air flow rate determination means 19 optimum rotation speed determination means 20 motor control means 21 abnormality determination means 22 abnormality processing means 24 differential Means 32 Blower amount estimating means 33 Target rotation speed judging means

Claims (3)

[Claims] 1. A rotation speed detecting means for detecting a rotation speed of a DC motor, a drive current detecting means for detecting information about a drive current of the DC motor, a detection output from the rotation speed detecting means and the drive current detection. A DC motor control device comprising a motor control means for controlling a drive voltage of the DC motor based on information including a detection output from the means, wherein the detection output from the drive current detection means is differentiated to A DC motor control device comprising: a differentiating unit that outputs the time change rate of the drive current of the DC motor to the drive voltage of the DC motor by outputting to the motor control unit. 2. A direct-current motor control device for rotating a direct-current motor by supplying power to a direct-current motor for rotating a fan for ventilation arranged in an air-flow passage of a combustor, wherein: Optimum air flow rate determination means for determining the optimal air flow rate based on the rotation speed, rotation speed detection means for detecting the rotation speed of the DC motor, drive current detection means for detecting information about the drive current of the DC motor, the drive current A flow path resistance determination unit that determines the flow path resistance of the air flow channel based on the detection output from the detection unit and the detection output from the rotation speed detection unit, and the optimum air flow determined by the optimum air flow rate determination unit. An optimum rotation speed judging means for judging an optimum rotation speed of the DC motor based on the air flow rate and the flow path resistance judged by the flow path resistance judging means; and a judgment result by the optimum rotation speed judging means. Motor control means for controlling the drive voltage of the DC motor based on the detection output from the rotation speed detection means, and by differentiating the detection output from the drive current detection means and outputting to the motor control means, A DC motor control device comprising: a differentiating unit that feeds back a temporal change rate of a drive current of the DC motor to a drive voltage of the DC motor. 3. A direct-current motor control device for rotating a direct-current motor by supplying power to a direct-current motor for rotating a fan for ventilation arranged in an air-flow passage of a combustor, wherein: Optimum air flow rate determination means for determining the optimal air flow rate based on the rotation speed, rotation speed detection means for detecting the rotation speed of the DC motor, drive current detection means for detecting information about the drive current of the DC motor, the drive current A flow passage resistance determination unit that determines the flow passage resistance of the air flow passage based on the detection output from the detection unit and the detection output from the rotation speed detection unit, and the flow passage determined by the flow passage resistance determination unit An air flow rate estimation unit that estimates the actual air flow rate based on the resistance and the detection output from the rotation speed detection unit, an optimum air flow rate determined by the optimum air flow rate determination unit, and the air flow rate estimation unit. The optimum rotation speed discriminating means for discriminating the optimum rotation speed of the DC motor based on the deviation from the estimated actual air flow rate, the discrimination result by the optimum rotation speed discriminating means, and the detection output from the rotation speed detecting means. And a motor control means for controlling the drive voltage of the DC motor based on the above, and the detection output from the drive current detection means is differentiated and output to the motor control means, thereby temporally changing the drive current of the DC motor. And a differentiating means for feeding back such a change rate to the drive voltage of the DC motor, the DC motor control device.