JPH08251986A - Fan motor controller for burner - Google Patents

Abstract

PURPOSE: To obtain a power saving fan motor controller having simple circuitry which is applicable to a fan motor in a forced draft burner being driven through a switching power supply. CONSTITUTION: A variable switching power supply comprises a transformer 28 having secondary winding producing an output voltage corresponding to the conduction rate of the primary winding, an element 29 for rectifying the output from the secondary winding, and a smoothing circuits L1, C1. Output from the smoothing circuit is applied to a fan motor 51. An error detection circuit 40 detects the error between the driving voltage being applied actually to the fan motor 51 and a set voltage designated by a microcomputer 45 constituting a burner. A control circuit 30 varies the conduction rate of a switching power supply 20 in the direction for eliminating the error upon receiving an output from the error detection circuit 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a fan motor used in a combustor such as a gas water heater for forced air supply to a combustion section, and more particularly to a fan motor controller using a switching power supply as a fan motor driving power supply. Regarding the improvement of.

[0002]

2. Description of the Related Art For example, when a combustion device is a gas water heater, when a user opens a faucet or the like to cause water flow, a water flow sensor or the like detects the water flow, and an ignition device ignites the burner. If it is a heater, the ignition device is activated by turning on the electric switch of the user or by opening the circulation valve in the hot water circulation type, and the burner is ignited.
In either case, of course, the burner, which is the combustion section, is supplied with gas as fuel through a fuel flow rate adjusting valve such as a gas proportional valve, but after the start of combustion, for example, the hot water temperature set by the user or indoor heating. A combustion control circuit, which can be configured by a microcomputer (hereinafter abbreviated as "microcomputer"), is nowadays generally equipped with a fuel flow rate adjusting valve so that the amount of supply gas is commensurate with the required amount of combustion depending on the required data such as set temperature. By controlling the valve opening of the water, the water supplied from the tap water through the heat exchanger heated appropriately, the circulating water for heating, or the heated medium such as indoor air is heated, The desired temperature is output. Feedback control is generally adopted for the control of the hot water supply temperature and room temperature, but this is not the object of improvement by the present invention, and therefore, illustration and detailed description thereof are omitted.

However, in such a combustion device,
In order to stably feed an appropriate amount of air to the burner at the time of combustion in the burner, a fan motor control device of which a typical example is shown in FIG. 5 has been used. To explain, in the case of using the commercial AC power supply 11, this is rectified by a rectifying bridge 12 or the like into a direct current, and a DC-DC converter (which is also generally a step-down type) is used to form a switching power supply 60. DC drive power of a voltage suitable for driving the fan motor 51 is obtained, and under this supply power, the rotation speed control circuit 70 controls the fan motor 51.
Is controlled so as to become an optimum value at each time, that is, a set rotation speed instructed by the microcomputer 45 as the combustion control circuit at each time.

Looking at the internal configurations of the switching power supply 60 and the rotation speed control circuit 70 individually, first, the switching power supply 60
Has a fixed frequency oscillator circuit 62, which is directly or more generally a driver transistor
The power switching transistor 27 is turned on and off via 63, whereby the primary current flowing in the primary winding of the transformer 28 inserted at both ends of the DC power source (the output of the rectifying circuit including the rectifying bridge 12 etc.) is fixed at the fixed frequency. Chopper with. As a result, the pulsating voltage obtained across the secondary winding of the transformer 28 is rectified by the rectifying diode 29,
A DC power supply with a small amount of ripples to be supplied to the fan motor 51 is obtained through a smoothing circuit including the choke coil L1 and the smoothing capacitor C1. The oscillation frequency of the fixed frequency oscillation circuit 62 is fixedly set according to the magnitude of the output voltage to be finally obtained at the output of the smoothing circuit. In other words, the conventionally used switching power supply 60 has a fixed output voltage. Generally, such switching power supply 60
In a sense, as a part of the smoothing circuit, a reverse current absorption diode D1 is provided in parallel with the secondary winding of the transformer 28, or the fixed frequency oscillation circuit 62 or the switching circuit is provided on the primary side of the transformer 28. In order to stabilize the operation of the transistors 27 and 63, a constant voltage circuit 21 that stabilizes the power supply voltage of them is also provided.

Next, the rotation speed control circuit 70 will be described. The combustion control circuit 45, which can be configured as the microcomputer 45, causes the fan motor 51 to have a predetermined rotation speed according to the amount of combustion in the combustion portion at that time. In order to supply a drive voltage of a magnitude that will be obtained, the comparator in the rotation speed control circuit 70 outputs the rotation speed control signal Sv, which is a voltage value signal of a magnitude (generally proportional) corresponding to the drive voltage. It is supplied to one input of 42 (a positive phase input in the case shown). On the other hand, the drive voltage value actually applied to the fan motor 51 is detected and divided by the resistance voltage dividing circuits 43 and 44 and applied to the other input of the comparator 42 (in this case, the negative phase input). . Here, for example, the drive voltage setting voltage value output from the microcomputer 45 is the drive voltage value (setting value) that should be actually applied to the fan motor 51.
If 1 / N is selected, the resistance voltage divider circuit 43,44
The partial pressure ratio of is also N (that is, the partial pressure ratio is 1 / N).

Therefore, when the actual driving voltage value divided by the resistance voltage dividing circuits 43 and 44 becomes lower than the value of the driving voltage setting voltage which is the rotation speed control signal Sv generated by the microcomputer 45, The output of the comparator 42 becomes high level, the driver transistor 48 is turned on, the power switching transistor 49 is also turned on, and the output current from the switching power supply 60 is the choke coil L2, the capacitor C2, and the reverse current absorption diode. The capacitor in the second smoothing circuit, which is given to the second smoothing circuit including D2.
C2 starts to be charged and its potential starts to rise, and this rising voltage is applied to the fan motor 51 to
The number of rotations of is on the rise.

As a result, when the comparator negative-phase input voltage via the resistance voltage dividing circuits 43 and 44 becomes higher than that on the positive-phase input side, the output of the comparator 42 is inverted to a low level. As the driver transistor 48 turns off, the power switching transistor 49 also turns off, the current supply from the switching power supply 60 is cut off, and the potential of the capacitor C2 in the second smoothing circuit begins to drop with a predetermined time constant, and the fan motor 51 Also starts to slow down. Then, when the actual applied voltage to the fan motor 51 becomes lower than the set voltage value instructed by the microcomputer 45 again, the output voltage of the comparator 42 becomes high level again through the driver transistor 48 by the mechanism described above. The power switching transistor 49 is turned on. By repeating such operations, the rotation speed control circuit 70 performs feedback control so as to keep the set value of the fan motor drive voltage instructed by the microcomputer 45 on average.

In addition to this, the actual rotation speed of the fan motor at each time is detected by the rotation speed sensor 47, and the rotation speed detection circuit 46 can understand the electric quantity by the microcomputer 45, for example, the actual rotation speed at a voltage value. The signal is converted to a signal and sent to the microcomputer 45, and the microcomputer 45 that receives this compares the set rotation speed at that time with the actual rotation speed, and if a difference of a predetermined value or more occurs in that value, In order to correct this, changes the magnitude (voltage value) itself of the rotation speed control signal Sv as a voltage value signal applied to the comparator 42 in the rotation speed control circuit 70. Thus, the fan motor 51 is also feedback-controlled with respect to its rotation speed, and is controlled so as to always maintain the set rotation speed.

[0009]

As described above, the conventional fan motor control device originally uses the switching power supply, as represented by the circuit configuration shown in FIG.
In addition, the magnitude of the drive voltage applied to the fan motor is also switching-controlled. Therefore, a total of two sets of smoothing circuits are required, one for each of the output of the switching power supply 60 and the output of the drive voltage controlling switching transistor 49, and even one of them cannot be omitted. In the case of switching control, the output voltage waveform generated as a result of switching is, in principle, a unipolar pulsating current voltage waveform that includes a large amount of high-frequency noise components, so noise components ( This is because such a smoothing circuit is indispensable for producing a DC voltage output with suppressed ripple component). But as you can see, switching power supply 60
When installing the rotation speed control circuit 70 on the circuit board, the most space-consuming and expensive thing is that the choke coils L1 and L2 and the smoothing capacitor C1, which are required for the first and second smoothing circuits, Large parts such as C2. Of course, as the smoothing circuit, a π type or the like may be adopted instead of the illustrated L type, but the situation does not change even with such a type. Rather, it often requires more large parts.

Further, the fixed output voltage value generated by the switching power supply 60 must be selected to be a size capable of maximally rotating the fan motor 51, but in the conventional configuration, the switching power supply 60 is always the maximum. The output voltage had to be reduced and used by the rotation speed control circuit 70 in the subsequent stage. Therefore, even from the viewpoint of power saving, it was not always in a desirable state.

The present invention has been basically made in view of the above-mentioned drawbacks of the conventional example, and is simpler even when a fan motor is driven by using a switching power supply and the number of revolutions thereof is controlled. It is an object of the present invention to provide a fan motor control device in which a smoothing circuit that requires at least a large-sized component is sufficient for one set and a switching power supply does not always need to operate at the maximum capacity.

[0012]

In order to achieve the above object, the present invention (a) rectifies an output voltage generated in a secondary winding of a transformer in a size corresponding to a duty ratio of a primary winding of a transformer, The switching power supply smoothed and applied to the fan motor, (b) The fan motor drive voltage value actually applied to the fan motor is monitored, and the actual drive voltage value is compared with the set voltage value instructed by the combustion control circuit. When an error is detected, the error detection circuit that detects the error, (c) When the error detection output of the error detection circuit is received, the duty ratio that changes the duty ratio of the transformer primary winding of the switching power supply in the direction of eliminating the error. Provided is a fan motor control device for a combustion device, which has a variable control circuit.

The inventor of the present invention, however, replaces the conventional feedback control relating to the fan motor drive voltage, and hence the feedback control for always keeping the fan motor rotation speed itself at the set rotation speed, with the drive actually flowing through the fan motor. By paying attention to the current and controlling it so as to maintain it at the set current value from time to time, it is possible to effectively avoid the risk of incomplete combustion even if there is load fluctuation of the fan motor (for example, exhaust system clogging). Proposal of possible control method (November 28, 1994)
Date submission: Japanese Patent Application No. 6-316090: Refer to the name "combustion control device"). Therefore, instead of the error detection circuit of the above configuration requirement (b), (d) the fan motor drive current value actually flowing in the fan motor is monitored, and the actually flowing drive current value is indicated by the combustion control circuit. By using an error detection circuit for detecting an error with respect to the set current value, the fan motor control device of the present invention is suitable for a feedback control mode focusing on such a drive current. Will be.

Further, as a subordinate aspect of the present invention, the duty ratio variable control circuit according to the above configuration requirement (c) includes (c1) a fixed frequency and fixed amplitude triangular wave oscillation circuit, and (c2) the triangular wave oscillation circuit. (C3) a comparator that inverts the output when the potential of one input exceeds the reference voltage of the other input by receiving the oscillation output in one of the two inputs and receiving the reference voltage in the other input. When the switching element that selectively turns on and off according to the reversal of the output of the transformer switches the primary current flowing in the transformer primary winding and the error detection output of the (c4) error detection circuit, it is input to the other input of the comparator. Also proposed is a fan motor control device including a reference voltage changing circuit for changing the applied reference voltage.

In this case, the reference voltage changing circuit of the configuration requirement (c4) divides the power supply voltage (c4-1) by a pair of voltage dividing resistors and applies the divided voltage to the other input of the comparator. A voltage dividing circuit, (c4-2) a light detecting element that selectively emits light depending on the presence or absence of an error detection output from the error detecting circuit, and a (c4-3) light detecting element that conducts when it receives the light emission. It is also possible to propose a fan motor control device in which one of a pair of voltage dividing resistors of a resistance voltage dividing circuit is connected in parallel with a resistor, and the light emitting element and the light detecting element are, for example, light emitting diodes. The phototransistor and the phototransistor are enclosed in a common housing, and the light-emitting diode and the phototransistor of a so-called photocoupler can be used.

According to the present invention, in addition to the above configuration requirement (a), the above configuration requirement (b), (c) or (d) may be replaced by
(e) A detection circuit that detects the actual rotation speed of the fan motor (or the drive voltage value that is actually applied or the drive current value that is actually flowing); and (f) The actual detection circuit that the detection circuit detects. When the rotation speed and the set rotation speed (or the drive voltage value and the set voltage value that are actually applied, or the drive current value and the set current value that are actually flowing) are compared and an error occurs between them In order to change the duty factor in the direction to eliminate the error, the combustion control circuit that changes the duty factor setting voltage and (g) the configuration requirements described above according to the change of the duty factor setting voltage of the combustion control circuit ( We also propose a fan motor controller for combustion equipment, which has a duty ratio variable control circuit that changes the duty ratio of the transformer primary winding of the switching power supply of a).

Also in this case, as a subordinate structure of the duty ratio variable control circuit of the constituent requirement (g), the duty ratio variable control circuit is (g1) a triangular wave oscillation circuit of fixed frequency and fixed amplitude,
2) The potential of one input exceeds the duty ratio setting voltage by receiving the oscillation output of the triangular wave oscillation circuit in one of the two inputs and receiving the duty ratio setting voltage generated by the combustion control circuit in the other input. A fan motor comprising a comparator that sometimes reverses the output and (g3) a switching element that selectively turns on and off according to the reversal of the output of the comparator to switch the primary current flowing in the transformer primary winding. A control device can also be proposed.

Further, in the present invention, in addition to the switching power supply of the above constituent requirement (a) and the rotation speed detection circuit of the constituent requirement (e), (h) the actual fan motor rotation speed and the set rotation speed ( Or, if the drive voltage value actually applied to the fan motor and the set voltage value, or the drive current value actually set to the fan motor and the set current value) are compared and an error occurs between them. We also propose a fan motor controller for combustion equipment, which has a combustion control circuit that varies the duty ratio of the transformer primary winding of the switching power supply in the direction of eliminating this error. In this case, more specifically, a switching element is provided in series with the transformer primary winding, and this switching element is turned on / off time determined based on the duty ratio control signal issued by the combustion control circuit of the above constituent requirement (h). The ratio (duty ratio) can be uniquely and directly turned on / off. The unique and direct is that
As can be seen from the above configuration requirements (c2) and (g2), for example, when a comparator is used, the time rate at which the output of the comparator is inverted changes depending on the voltage values of both inputs (for example, In addition to changing the reference voltage, the timing at which the output of the comparator inverts changes even if the waveform of the triangular wave oscillated by the triangular wave oscillator circuit changes), but it depends on the duty ratio control signal issued by the combustion control circuit. It is only that the on / off time ratio of the switching elements inserted in series in the transformer primary winding is determined. The above configuration requirements
The optional configuration requirements in parentheses in (e), (f), and (h) are:
In the summary structure of the present application, each claim is a separate claim.

[0019]

FIG. 1 shows a fan motor control device as a first embodiment of the present invention. The device of the present embodiment described here is the conventional example described with reference to FIG. It is a modification device for. Therefore, the components denoted by the same reference numerals as in FIG. 5 may be the same as or similar to those in the conventional device shown in FIG. 5, and the above description is referred to for each of them. To do.
Throughout the embodiments of the present invention shown in FIGS. 1 to 4, which will be described below, constituent elements having the same reference numerals indicate constituent elements that may correspond to or the same as each other. It should be noted that, if it is stated in advance, the present invention can be applied to any combustion device of the type that forcibly supplies the air amount corresponding to the combustion amount to the combustion part, and the type of fuel etc. is there.

Also in the fan motor control device of the present invention, the power for driving the fan motor 51 is the switching power supply.
Obtained by 20. However, unlike the conventional device shown in FIG. 5, in the present invention, the output voltage itself of the switching power supply 20 is variably controlled to control the fan motor rotation speed. That is, the switching power supply 20 is configured as a variable switching power supply capable of varying the output voltage.

First, the variable switching power supply 20 has a duty ratio variable control circuit 30, in which there is a triangular wave oscillating circuit 22 for outputting a triangular wave waveform having a fixed frequency and a fixed amplitude. Is applied to one input, in this case the positive phase input. On the other hand, a divided voltage obtained by dividing the power supply voltage generated by the constant voltage circuit 21 by the pair of resistors 23 and 24 is applied as a reference voltage to the negative phase input of the comparator 26. Constant voltage circuit
The 21 power inputs are commercial AC power supplies as the power supply for this controller.
When 11 is used, the DC power is rectified by a rectification circuit such as a rectification bridge 12 and appropriately smoothed by passing it through a smoothing capacitor.

Of the pair of voltage dividing resistors of the resistor voltage dividing circuits 23 and 24, the resistor 25 located in the upper side in this case is the resistor 25.
And a series circuit of a phototransistor PT as an example of the photodetector are connected in parallel. Therefore, when the phototransistor PT is not conducting (when light is not detected), the reference voltage applied to the negative phase input of the comparator 26 is the output voltage of the constant voltage circuit 21 (power supply voltage), which is a pair of resistors. 23, 24
Relatively low voltage value V1 divided by the resistance voltage divider circuit
However, when the phototransistor PT detects light and becomes conductive, the resistor 25 is further connected in parallel with the upper resistor 23, so that the reference voltage applied to the negative phase input of the comparator 26 has a relatively high voltage value. Become V2.

However, the triangular wave oscillating waveform from the triangular wave oscillating circuit 22 applied to the positive phase input of the comparator 26 can be designed to be fixed for each model in terms of its frequency and amplitude (maximum amplitude). When the voltage value V1 is applied as the reference voltage to the comparator 26, as shown in the lower left of the diagram schematically showing the relationship between the triangular wave oscillation waveform and the reference voltages V1 and V2, The oscillation output voltage is higher for a longer period of time, and the Ton1
During this period, the comparator output becomes high level in this case as the first state, and conversely, when the reference voltage V2 is applied to the input, the time when the oscillation output voltage from the triangular wave oscillation circuit 22 is higher. Becomes shorter, the comparator output is in the first state for a relatively short time Ton2. The first state output of the comparator 26, ie the high level output in this case, causes the switching element 27 (in this case a bipolar power transistor 27) which is in series with the primary winding of the transformer 28 of the variable switching power supply 20 to conduct. Therefore, the DC current from the DC power supply (the output of the rectifying circuit including the rectifying bridge 12) is supplied to the primary winding of the transformer 28 only during the time Ton1 or Ton2. Therefore, changing the reference voltages V1 and V2 controls the duty ratio of the primary winding of the transformer 28 through changing the on / off time ratio of the switching element 27, and eventually controls the secondary output voltage of the transformer 28. It will be. Of course, the longer the primary duty ratio, the higher the secondary output voltage.

Since the output voltage appearing on the secondary side of the transformer 28 has a unipolar pulsating current waveform containing a large amount of high frequency components, it is rectified by the rectifying diode 29 and then smoothed by the choke coil L1 and the smoothing capacitor C1. And then applied to both ends of the fan motor 51. A diode D1 in parallel with the secondary winding of transformer 28 is desirable, as it is for reverse current absorption, as in the prior art.

The value of the drive voltage applied to the fan motor 51 from time to time, that is, the value of the output voltage of the variable switching power supply 20, is determined by the combustion control circuit 45 configured by the microcomputer 45 according to the recent trend in this embodiment. Be instructed.
For example, when combustion occurs in a combustion unit or burner (not shown), the combustion control circuit or the microcomputer 45 responds to the combustion amount at each time, based on fan rotation speed data stored in advance in a memory means (not shown), A rotation speed setting signal Sv is issued to the fan motor to instruct the rotation speed to be realized at each time. In this embodiment, the rotation speed setting signal Sv is a voltage signal indicating the set voltage value to be applied to the fan motor, and is selected to be 1 / N of the set voltage value. Comparator 42 which is a component
Is applied to one input (in this embodiment, the positive phase input). On the other hand, the drive voltage value actually applied to the fan motor 51 is detected and divided by the resistance voltage dividing circuits 43 and 44 having the voltage division ratio 1 / N, that is, the voltage division ratio N, and then the other comparator 42. The input, and thus the negative phase input in this embodiment, is applied.

As a result, the actual fan motor drive voltage value divided by the resistance voltage dividing circuits 43 and 44 is the microcomputer 45.
When an error that is higher than the value of the drive voltage setting voltage, which is the rotation speed control signal Sv, is generated by the comparator 42
Becomes a low level, and in this case, the light emitting diode DL as a light emitting element that operates by the low level output of the comparator 42 emits light, and this light emission is captured by the phototransistor PT described above and the phototransistor concerned. PT turns on. Then, the reference voltage applied to the input of the comparator 26 in the duty ratio variable control circuit 30 changes from the previous value V1 to the higher value V2 by the mechanism already described, and as a result, the on / off duty ratio of the switching element 27 is changed. Becomes smaller (ON time becomes shorter as shown by Ton2 in the figure), the primary winding duty ratio of the transformer 28 is reduced, the secondary output voltage is reduced, and the drive voltage value actually applied to the fan motor 51 is reduced. In the direction of approaching the set value indicated by the microcomputer 45 (that is, in the direction of eliminating the error)
Change occurs.

On the contrary, when the drive voltage value actually applied to the fan motor 51 becomes lower than the set value instructed by the microcomputer 45, the output of the comparator 42 in the error detection circuit 40 is output. Becomes a high level and the cathode of the light emitting diode DL is pulled up to a high level, so that the light emission ends, and as a result, the phototransistor PT also becomes non-conductive, and the comparator 26 in the duty ratio variable control circuit 30 Since the reference voltage applied to the negative phase input changes to a relatively low value V1 by the resistance voltage divider circuit including only the pair of resistors 23 and 24, the ON / OFF duty ratio of the switching element 27 becomes large (the ON time is shown as Ton1 in the figure. The primary winding duty ratio of the transformer 28 increases and the secondary output voltage rises. This allows
The drive voltage actually applied to the fan motor 51 also tends to increase, and changes to a direction in which there is no error with the set voltage value instructed by the microcomputer 45.

By repeating such operations,
The value of the drive voltage actually applied to the fan motor 51 is feedback-controlled so as to keep the set voltage value instructed by the microcomputer 45 on average. Of course, the magnitude of the rotation speed setting signal Sv generated by the microcomputer 45 at each time, that is, the voltage value as the drive voltage setting voltage in this case, is the feed air corresponding to the combustion amount at each time as described above. The fan motor rotation speed that satisfies the amount is set to a value that can be obtained, but in general, feedback control can also be adopted for this rotation speed itself. This point is not particularly different from the case of the conventional example,
The actual speed of the fan motor at that time
Is detected by the rotation speed detection circuit 46, and converted by the rotation speed detection circuit 46 into an actual rotation speed signal with an electric quantity that can be understood by the microcomputer 45, for example, a voltage value, and read by the microcomputer 45. Then, in the microcomputer 45, the set rotational speed at that time is compared with this actual rotational speed, and if there is a difference of a predetermined value or more, in order to correct this difference, the comparison in the error detection circuit 40 is performed. The magnitude (voltage value) of the rotation speed control signal Sv as a voltage value signal applied to the device 42 is changed.

When the output of the comparator 42 in the error detection circuit 40, that is, the error detection output is sent to the duty ratio variable control circuit 30, a light emitting element such as a light emitting diode DL and a phototransistor PT, etc., as shown in the figure. The optical transmission using the photodetector element is used for electrical insulation between the primary side and the secondary side of the transformer 28. Further, as also shown in the figure, the combination of such a light emitting element and a light detecting element is
It is relatively inexpensive to obtain a so-called photocoupler 41 in which those elements are housed in a common housing, and the use of such a photocoupler 41 is effective for downsizing the device. Further, in the case shown, the microcomputer 45
The light emitting element DL is configured to emit light when the drive voltage value actually applied to the fan motor 51 is higher than the set voltage value instructed by, but the direction of the light emitting element DL is reversed. Alternatively, if the positive-phase and negative-phase input relations of the comparator 42 are reversed, light is emitted when the drive voltage value actually applied to the fan motor 51 is lower than the set voltage value instructed by the microcomputer 45. It can be changed so that the element DL emits light. In such a case, the photodetector PT and the resistor
The series circuit of 25 may be inserted in parallel with the lower resistor 24 of the pair of voltage dividing resistors 23 and 24 forming the resistance voltage dividing circuit in the duty ratio variable control circuit 30.

The above-mentioned embodiment shown in FIG. 1 is a feedback control in consideration of the fan motor drive voltage. However, as described above, the applicant has already considered the fan motor drive current value. The feedback control method of is also proposed. Therefore, when the present invention is applied to provide a fan motor control device suitable for this, the circuit configuration as shown in FIG. 2 can be adopted. Descriptions of parts common to those of the apparatus of the embodiment shown in FIG. 1 will be omitted, but what is changed is that
In the error detection circuit 40, the resistance voltage dividing circuits 43 and 44 in the previous embodiment are eliminated, and instead the drive current value actually flowing in the fan motor 51 is supplied to the negative phase input of the comparator 42 as a voltage. The voltage across the current detection resistor 48 that is converted to a value and detected is applied, and the rotation speed setting signal Sv given from the microcomputer 45 to the positive phase input of the comparator 42 becomes the drive current setting voltage value. It is that.

The feedback control mechanism itself of the apparatus shown in FIG. 2 is the same as that of the apparatus shown in FIG. 1 described above. When the magnitude of the drive current actually flowing in 51 causes an error, the reference voltage in the duty ratio variable control circuit 30 is the same as in FIG. 1 according to the output of the comparator 42 in the error detection circuit 40. The voltage values V1 and V2 (FIG. 1) are selectively changed, whereby the secondary output voltage of the transformer 28 is finally selectively changed and the driving current value actually flowing in the fan motor 51 is changed by the microcomputer 45. Is variably controlled to eliminate an error with respect to the set value instructed by. In addition, the value of such fan motor drive current can be changed from time to time by the microcomputer.
When a control method for keeping the set current value indicated by 45 as constant as possible is adopted, a rotation speed sensor for detecting the actual rotation speed of the fan motor 51 as shown by a virtual line in FIG. In many cases, the rotation speed detection circuit 46 for inputting the detection output 47 to the microcomputer 45 is unnecessary. It is not a control mode that always keeps the fan motor at the set speed, but it is insufficient when the fan motor load is light (even if the exhaust system is clogged) even if the combustion amount is the same, depending on how the exhaust system is clogged. To increase the amount of air that tends to occur,
This is because by maintaining the drive current at the set value, the drive voltage is allowed to increase and the fan motor rotation speed is intentionally increased.

It can be seen that the apparatus of the embodiment shown in FIGS. 1 and 2 can be much smaller and cheaper than the conventional apparatus shown in FIG. First, since the output voltage of the switching power supply itself is changed to change and control the driving voltage value or the driving current value applied to the fan motor 51 at each time, the switching power supply that was conventionally required
The rotation speed control circuit 70 that selectively throttles the output of 60 is omitted,
Of course, the second smoothing circuit L2, C2, D2 included in it
The large-sized power switching element 49 becomes unnecessary. Further, unlike the conventional fixed output voltage type switching power supply 60, the switching power supply 20 does not always need to operate at the maximum capacity, which is advantageous in terms of energy consumption.

However, the apparatus of the embodiment of the present invention shown in FIG. 3 is an example of a configuration in which such characteristics of the present invention are more prominently shown as a fan motor control apparatus suitable for feedback control of the fan motor rotation speed. Is shown.

To explain, as in the embodiment shown in FIGS. 1 and 2, a variable duty factor control circuit 30 is provided on the primary side of the variable switching power source 20, and one input of the comparator 26 In this case, the output of the triangular wave oscillation circuit 22 of fixed frequency and fixed amplitude is applied to the positive phase input, but the difference is that
The rotational speed setting signal Sv from the microcomputer 45 is directly applied to the negative phase input of the comparator 26. Following the operation, the actual rotation speed of the fan motor 51 at each time is given from the rotation speed sensor 47 to the microcomputer 45 via the rotation speed detection circuit 46. In the microcomputer 45, the fan motor set rotational speed determined to be appropriate for the combustion amount at each time is compared with this actual rotational speed, and if there is an error between them,
The duty ratio setting voltage for varying the duty ratio of the switching element 27 that controls the switching of the primary current of the transformer 28 in the direction to eliminate this error is changed and applied to the negative phase input of the comparator 26. That is, in this embodiment, the rotation speed setting signal Sv
Is a duty ratio setting voltage.For example, when the actual rotation speed of the fan motor 51 is higher than the setting rotation speed set by the microcomputer itself, the microcomputer 45 outputs the duty ratio setting voltage applied to the comparator negative phase input. By increasing the value, the ON time of the switching element 27 is shortened as shown by Ton2 in relation to the oscillation output waveform of the triangular wave oscillation circuit 22 as schematically shown in FIG. 1, and the output voltage of the switching power supply 20 is reduced. The driving voltage applied to the fan motor is lowered to lower the rotation speed. Conversely, when the actual rotation speed of the fan motor 51 is lower than the set rotation speed set by the microcomputer itself, the microcomputer 45 lowers the value of the duty ratio setting voltage applied to the comparator negative phase input, and As schematically shown in FIG. 1, the ON time of the switching element 27 is lengthened as shown by Ton1 in relation to the oscillation output waveform of the triangular wave oscillation circuit 22, and the output voltage of the switching power supply 20 is increased to increase the fan motor. The applied drive voltage is increased to increase the rotation speed. Therefore, the duty ratio setting voltage generated by the microcomputer 45 is also the drive voltage setting voltage.

Obviously, in the embodiment apparatus of FIG.
The secondary side circuit of the variable switching power supply 20 is extremely simplified, and substantially only the output of the smoothing circuit attached to the switching power supply 20 is directly applied to the fan motor 51. It should be noted that, in comparison with the embodiment apparatus shown in FIGS. 1 and 2, in addition to the combustion control circuit, the microcomputer 45 also constitutes the error detection circuit 40 including the rotation speed detection circuit 46. become.

The device of the fourth embodiment of the present invention shown in FIG. 4 is an example of a configuration in which the device of the third embodiment shown in FIG. 3 is further simplified. That is, the combustion control circuit microcomputer 45
Not only serves as the error detection circuit 40, but also constitutes the duty ratio variable control circuit 30, and the actual fan motor rotation speed detected at that time from the rotation speed sensor 47 through the rotation speed detection circuit 46. On the other hand, if the number of revolutions set by the microcomputer itself is higher, for example, in order to increase the duty ratio of the primary current of the variable switching power supply transformer 28 or the ON time of the switching element 27 in the direction of eliminating the error, in the figure As shown schematically in the lower left, the duty ratio control is a pulse train signal with a long time Ton for which the rotation speed control signal Sv is on (a large duty ratio Ton / (Ton + Toff)). Emits a signal, variable switching power supply 20
Increase the output voltage of. On the contrary, when the actual fan motor speed becomes higher than the set speed, the microcomputer 45 shortens the ON time of the switching element 27 and lowers the output voltage of the variable switching power supply 20. To reduce the fan motor drive voltage, the duty ratio
The duty ratio control signal, which is a small pulse train signal of Ton / (Ton + Toff), is issued.

With such a device configuration, not only the circuit is ultimately simplified, but also the variable switching power source is provided.
The duty factor of 20 (on / off time ratio of switching element) is
The control can be performed uniquely and directly only by the duty ratio control signal generated by the microcomputer 45 regardless of other signal factors.

The embodiment apparatus shown in FIG. 4 and the embodiment apparatus previously described with reference to FIG. 3 also have a feedback control system in consideration of the fan motor drive voltage value as shown in FIG. Alternatively, it can be modified to be suitable for the control method in consideration of the fan motor drive current as shown in FIG. For example, the voltage across the fan motor is divided by the resistance voltage divider circuit 4 as shown in FIG.
If there is an error between the set value related to the drive voltage set by the microcomputer itself and the actual drive voltage value, the variable switching power supply is used to eliminate it. The microcomputer 45 can be configured to generate a rotation speed control signal Sv for changing the output voltage of the fan motor 51, and the voltage across the current detection resistor 48 (see FIG. 2) inserted in series with the fan motor 51 can be supplied to the microcomputer 45. If an error occurs between the set value related to the drive current set by the microcomputer itself and the actual drive current value by inputting and detecting it, change the output voltage of the variable switching power supply to eliminate this error. The rotation speed control signal Sv can be generated from the microcomputer 45.

[0039]

According to the present invention, as a fan motor control device for various combustion equipment, one set of smoothing circuits for fan motor drive current, which requires large and expensive parts, can be used.
It is released from the constraint that at least two sets were required as in the past. Naturally, this leads to downsizing and cost reduction of the device. Further, it is possible to escape from the situation where the switching power supply must always be operated at the maximum capacity, and it is possible to use the output power required for driving the fan motor at any time, so that it is possible to provide a power-saving fan motor control device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a fan motor control device of the present invention.

FIG. 2 is a schematic configuration diagram of a second embodiment of the fan motor control device of the present invention.

FIG. 3 is a schematic configuration diagram of a third embodiment of the fan motor control device of the present invention.

FIG. 4 is a schematic configuration diagram of a fourth embodiment of a fan motor control device of the present invention.

FIG. 5 is a schematic configuration diagram of a typical circuit of a conventional fan motor controller for a combustion device.

[Explanation of symbols]

 20 variable switching power supply, 21 constant voltage circuit, 22 triangular wave oscillation circuit, 23, 24 resistance voltage divider circuit, 25 resistance, 26 comparator, 27 switching element, 28 transformer, 29 rectifier diode, 30 duty ratio control circuit, 40 error Detection circuit, 41 photo coupler, 42 comparator, 43, 44 resistance voltage divider circuit, 45 combustion control circuit or microcomputer, 46 rotation speed detection circuit, 47 rotation speed detection sensor, 51 fan motor, L1, C1 smoothing circuit, DL light emission Element or light emitting diode, PT light detection element or phototransistor.

Claims (12)

[Claims] 1. A controller for a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A switching power supply having a smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the smoothed output to the fan motor; monitoring the fan motor drive voltage value actually applied to the fan motor, An error detection circuit for detecting the error when the drive voltage value has an error with respect to the set voltage value instructed by the combustion control circuit; and a direction for eliminating the error when the error detection output of the error detection circuit is received. A fan motor controller for a combustion device, comprising: a duty ratio variable control circuit for varying a duty ratio of the transformer primary winding of a switching power supply. 2. A controller of a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the smoothed output to the fan motor; and monitoring the fan motor drive current value actually flowing in the fan motor, An error detection circuit that detects the error when the flowing drive current value has an error with respect to the set current value instructed by the combustion control circuit; and eliminates the error when the error detection output of the error detection circuit is received. Direction control circuit for varying the duty ratio of the primary winding of the transformer of the switching power supply in a direction. 3. A device according to claim 1 or 2;
The duty ratio variable control circuit receives a fixed frequency and fixed amplitude triangular wave oscillation circuit and an oscillation output of the triangular wave oscillation circuit at one of two inputs, and receives a reference voltage at the other input, thereby A comparator that inverts the output when the potential exceeds the reference voltage of the other input,
Selectively turning on and off in response to the inversion of the output of the comparator,
A switching element for switching the primary current flowing through the primary winding of the transformer and a reference voltage changing circuit for changing the reference voltage given to the other input of the comparator when receiving the error detection output of the error detection circuit. A fan motor control device for a combustion device, comprising: 4. The device according to claim 3, wherein the reference voltage changing circuit divides the power supply voltage by a pair of voltage dividing resistors and applies the divided voltage to the other input of the comparator. A circuit, a photodetector that selectively emits light depending on the presence or absence of the error detection output from the error detector, a photodetector that conducts when it receives the light, and a resistor voltage divider circuit that is in series with the photodetector. And a resistor that is connected in parallel with one of the pair of voltage dividing resistors. 5. A control device for a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A switching power supply having a smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the same to the fan motor; a rotation speed detection circuit for detecting an actual rotation speed of the fan motor; The actual rotation speed detected by the circuit is compared with the set rotation speed, and if there is an error between them, the duty ratio setting voltage is changed in order to change the duty ratio in the direction of eliminating the error. Combustion control circuit; and a duty ratio variable control circuit for varying the duty ratio of the primary winding of the transformer of the switching power supply according to the change of the duty ratio setting voltage of the combustion control circuit; Fan motor controller for equipment. 6. A controller of a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A smoothing circuit that rectifies and smoothes the output of the secondary winding and applies the smoothed output to the fan motor; and a drive voltage detection circuit that detects a drive voltage value that is actually applied to the fan motor. For comparing the actual drive voltage value detected by the drive voltage detection circuit and the set voltage value, and if an error occurs between them, the duty ratio is changed to eliminate the error. A combustion control circuit that changes the voltage;
And a duty ratio variable control circuit for varying the duty ratio of the transformer primary winding of the switching power supply according to the change of the duty ratio setting voltage of the combustion control circuit. apparatus. 7. A controller for a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A switching power supply having a smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the same to the fan motor; and a drive current detection circuit for detecting a drive current value actually flowing in the fan motor. The actual drive current value detected by the drive current detection circuit is compared with the set current value, and when an error occurs between them, the duty ratio is changed to eliminate the error. And a duty ratio variable control circuit for varying the duty ratio of the transformer primary winding of the switching power supply according to the change of the duty ratio setting voltage of the combustion control circuit. Combustion device fan motor controller . 8. The device according to claim 5, 6 or 7, wherein the duty ratio variable control circuit has a triangular wave oscillation circuit having a fixed frequency and a fixed amplitude, and an oscillation output of the triangular wave oscillation circuit having one of two inputs. And a comparator for inverting the output when the potential of the one input exceeds the duty ratio setting voltage by receiving the duty ratio setting voltage generated by the combustion control circuit at the other input, And a switching element that selectively turns on and off according to the inversion of the output of the comparator and switches the primary current flowing through the transformer primary winding. . 9. A controller of a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A switching power supply having a smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the same to the fan motor; a rotation speed detection circuit for detecting an actual rotation speed of the fan motor; Combustion that compares the actual rotational speed detected by the circuit with the set rotational speed and, if an error occurs between them, changes the duty factor of the transformer primary winding of the switching power supply in the direction of eliminating the error. A fan motor control device for a combustion device, comprising: a control circuit; 10. A controller of a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A smoothing circuit that rectifies and smoothes the output of the secondary winding and applies the smoothed output to the fan motor; and a drive voltage detection circuit that detects a drive voltage value that is actually applied to the fan motor. Comparing the actual drive voltage value detected by the drive voltage detection circuit with a set voltage value, and when an error occurs between them, in the direction of eliminating the error, the transformer primary winding of the switching power supply A combustion motor fan motor control device comprising: a combustion control circuit for varying a duty ratio; 11. A controller of a fan motor for forced air supply to a combustion section; a transformer for producing an output voltage in a secondary winding, the output voltage having a magnitude corresponding to a duty ratio of a primary winding, and the transformer. A switching power supply having a smoothing circuit for rectifying and smoothing the output of the secondary winding and applying the same to the fan motor; and a drive current detection circuit for detecting a drive current value actually flowing in the fan motor. The actual drive current value detected by the drive current detection circuit is compared with the set current value, and when an error occurs between them, energization of the transformer primary winding of the switching power supply in the direction of eliminating the error. A combustion control circuit for varying the rate, and a fan motor control device for combustion equipment. 12. The apparatus according to claim 9, 10 or 11, wherein the primary winding of the transformer is uniquely and directly determined on the basis of a duty ratio control signal generated by the combustion control circuit. A switching element to be used in series is inserted in series;