DC fan control circuit, gas water heater and wind pressure resistance control method and system thereof

Abstract

The present invention relates to a DC fan control circuit, a gas water heater and a wind pressure resistance control method and system thereof, comprising: a main controller for outputting a first level signal and a second level signal; a speed feedback circuit connected to the fan and the main controller, for obtaining fan speed information and sending it to the main controller; a current sampling circuit connected to the fan, for obtaining the real-time working current of the fan; a constant current control circuit connected to the fan, the current sampling circuit and the main controller, for receiving a second level signal and outputting a speed regulation level to maintain the real-time working current unchanged; an enabling control circuit connected to the constant current control circuit and the main controller, for receiving a first level signal to turn on or off the speed regulation level output. The implementation of the present invention can quickly realize the wind pressure resistance of the gas water heater through a simple circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of gas water heaters, and more specifically to a direct current fan control circuit, a gas water heater, and a wind pressure resistance control method and system thereof. Background Art

[0002] The requirements for flue blockage of gas water heaters are clearly stipulated both domestically and internationally, that is, the wind pressure must meet domestic or international standards to ensure that during the use of household gas water heaters, even when there is backflow of wind from the outside, the smoke generated by gas combustion can be discharged outdoors in time. However, in actual use, due to the increasing popularity of high-rise buildings in cities, the operating environment of most ordinary gas water heaters is not ideal. When there is wind in the operating environment, reverse wind pressure may be generated in the exhaust channel of the gas water heater, resulting in obstruction of the gas water heater exhaust. At this time, the combustion air flow may be reduced, causing the combustion state to deteriorate or even flameout. At the same time, smoke exceeds the standard, posing a safety hazard. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a DC fan control circuit, a gas water heater and a wind pressure resistance control method and system thereof in view of the above-mentioned technical defects of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: construct a DC fan control circuit, including:

[0005] A main controller for outputting a first level signal and a second level signal;

[0006] A speed feedback circuit connected to the fan and the main controller, used to obtain the fan speed information and send it to the main controller;

[0007] A current sampling circuit connected to the fan and used to obtain the real-time working current of the fan;

[0008] A constant current control circuit connected to the fan, the current sampling circuit and the main controller, configured to receive the second level signal and output a speed adjustment level to maintain the real-time working current unchanged when the second level signal remains unchanged;

[0009] An enabling control circuit connected to the constant current control circuit and the main controller, and used for receiving the first level signal to turn on or off the speed regulation level output according to the first level signal.

[0010] Preferably, the constant current control circuit comprises a first comparator and a differential integration unit;

[0011] The same-direction input terminal of the first comparator is connected to the enabling control circuit, the reverse input terminal of the first comparator is connected to the output terminal of the first comparator, and the output terminal of the first comparator is connected to the fan;

[0012] A first end of the differential integration unit is connected to the current sampling circuit, a second end of the differential integration unit is connected to the main controller, and a third end of the differential integration unit is connected to the non-inverting input end of the first comparator.

[0013] Preferably, the differential integration unit includes a second comparator, a first capacitor, a first resistor, a second capacitor, a second resistor, a third resistor and a third capacitor;

[0014] The non-inverting input terminal of the second comparator is connected to the main controller via the second resistor, and the non-inverting input terminal of the second comparator is also grounded via the third resistor and the third capacitor connected in parallel, the reverse input terminal of the second comparator is connected to the current sampling circuit, and the reverse input terminal of the second comparator is also connected to the output terminal of the second comparator via the first capacitor, and the output terminal of the second comparator is grounded via the first resistor and the second capacitor connected in parallel.

[0015] Preferably, the current sampling circuit comprises a fourth resistor, a first end of the fourth resistor is connected to the fan, a second end of the fourth resistor is grounded, and a first end of the fourth resistor is also connected to an inverting input end of the second comparator.

[0016] Preferably, the enabling control circuit comprises a first transistor, a fourth capacitor of a voltage stabilizing diode;

[0017] The positive electrode of the voltage regulator diode is connected to the non-inverting input terminal of the first comparator, the negative electrode of the voltage regulator diode is grounded, the positive electrode of the voltage regulator diode is also connected to the collector of the first transistor, the emitter of the first transistor is grounded, and the base of the first transistor is connected to the main controller; the collector of the first transistor is also grounded via the fourth capacitor.

[0018] Preferably, the speed feedback circuit includes a second transistor, a fifth resistor, a fifth capacitor, a sixth resistor, a seventh resistor and a sixth capacitor;

[0019] The base of the second transistor is connected to the fan, the collector of the second transistor is connected to a power supply via the sixth resistor, the collector of the second transistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to the main controller, the other end of the seventh resistor is also grounded via the sixth capacitor, the collector of the second transistor is also grounded via the fifth resistor and the fifth capacitor connected in parallel, and the emitter of the second transistor is grounded.

[0020] The present invention also constructs a gas water heater, comprising a DC fan control circuit as described in any one of the above items.

[0021] The present invention also provides a method for controlling wind pressure resistance of a gas water heater, which is applied to the gas water heater as described above, and comprises:

[0022] S1. confirming the working state of the internal heating working circuit, and when the working state is a heating state, obtaining the working current of the fan;

[0023] S2. acquiring a preset fan speed corresponding to the working current of the fan according to the working current of the fan;

[0024] S3, obtaining the real-time fan speed of the fan, and comparing the real-time fan speed with the preset fan speed. If the real-time fan speed is greater than the preset fan speed, executing step S4; if the real-time fan speed is less than the preset fan speed, executing step S5; if the real-time fan speed is equal to the preset fan speed, executing step S6;

[0025] S4, increasing the operating current of the fan according to the first preset step, and obtaining the corresponding preset fan speed according to the new operating current of the fan, and executing step S3;

[0026] S5, reducing the operating current of the fan according to a second preset step, and obtaining a corresponding preset fan speed according to the new operating current of the fan, and executing step S3;

[0027] S6. Control the fan to operate at the current operating current.

[0028] Preferably, the method further comprises:

[0029] S51, determining whether the preset fan speed is the minimum fan speed, if so, executing step S6, if not, executing step S5.

[0030] Preferably, the method further comprises:

[0031] S41, determining whether the preset fan speed is the maximum fan speed, if yes, executing step S7, if no, executing step S4;

[0032] S7: Turn off the heating circuit of the water heater and / or generate an excessive wind pressure alarm.

[0033] Preferably, the method further comprises:

[0034] The working level of the fan is acquired according to the working current of the fan, and the corresponding first preset step or second preset step is acquired according to the working level.

[0035] Preferably, the first preset steps are equal or unequal; or the second preset steps are equal or unequal.

[0036] The present invention also constructs a gas water heater wind pressure resistance control system, comprising:

[0037] A first judging unit, used to confirm the working state of the internal heating working circuit;

[0038] A first acquisition unit, used for acquiring the working current of the fan when the working state is a heating state;

[0039] A second acquisition unit, configured to acquire a preset fan speed corresponding to the working current of the fan according to the working current of the fan;

[0040] A third acquisition unit, used to acquire the real-time fan speed of the fan;

[0041] A second judgment unit, used for comparing the relationship between the real-time fan speed and the preset fan speed;

[0042] A first execution unit, configured to increase the operating current of the fan according to a first preset step when the real-time fan speed is greater than the preset fan speed;

[0043] A second execution unit, configured to reduce the operating current of the fan according to a second preset step when the real-time fan speed is less than the preset fan speed;

[0044] The third execution unit is used to control the fan to operate at a current operating current when the real-time fan speed is equal to the preset fan speed.

[0045] The implementation of the DC fan control circuit, gas water heater wind pressure resistance control method and system of the present invention has the following beneficial effects: the wind pressure resistance of the gas water heater can be quickly achieved through a simple circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0047] Figure 1 It is a circuit block diagram of the DC fan control circuit of the present invention;

[0048] Figure 2 is a circuit schematic diagram of a first embodiment of a DC fan control circuit of the present invention;

[0049] Figure 3It is a program flow chart of an embodiment of a method for controlling wind pressure resistance of a gas water heater according to the present invention;

[0050] Figure 4 is a program flow chart of another embodiment of the wind pressure resistance control method of a gas water heater of the present invention;

[0051] Figure 5 is a program flow chart of another embodiment of the wind pressure resistance control method of a gas water heater of the present invention;

[0052] Figure 6 It is a logic block diagram of an embodiment of a gas water heater wind pressure resistance control system of the present invention. DETAILED DESCRIPTION

[0053] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0054] like Figure 1As shown, in the first embodiment of the DC fan control circuit of the present invention, it includes: a main controller 150 for outputting a first level signal and a second level signal; a speed feedback circuit 110 connected to the fan and the main controller 150, for obtaining the fan speed information and sending it to the main controller 150; a current sampling circuit 130 connected to the fan, for obtaining the real-time working current of the fan; a constant current control circuit 140 connected to the fan, the current sampling circuit 130 and the main controller 150, for receiving the second level signal and outputting the speed regulation level to maintain the real-time working current unchanged when the second level signal remains unchanged; an enable control circuit 140 connected to the constant current control circuit 140 and the main controller 150, for receiving the first level signal to turn on or off the speed regulation level output according to the first level signal. In a specific embodiment, the main controller 150 outputs a first level signal and a second level signal, wherein the first level signal is used to drive the enable control circuit 140, and the second level signal is used to drive the constant current control circuit 140, the constant current control circuit 140 connects the fan and the main controller 150, and the second level signal output by the main controller 150 is output through the constant current control circuit 140 to output a stable speed regulation level, so that the real-time working current of the fan is stable and the wind speed is stable. The output of the second level signal by the main controller 150 is determined by its internal control circuit, for example, when setting the fan speed, the second level signal corresponding to the set speed value is input. The enable control circuit 140 is connected to the constant current control circuit and the main controller 150, and turns on or off the speed regulation level output according to the first level signal, that is, when the first level signal drives the enable control circuit 140 to turn off the speed regulation level output, the fan cannot start working, and when the first level signal drives the enable control circuit 140 to turn on the speed regulation level output, the fan will work normally according to the speed corresponding to the speed regulation level, so the first level signal can also be understood as an enable level signal. The current sampling circuit 130 is connected to the fan and is used to obtain the real-time working current of the fan when it is working. When the fan is working internally, it may be affected by the outside world, such as the external wind pressure, and its real-time working current will change to a certain extent. At this time, the constant current control circuit 140 connected to the current sampling circuit 130 adjusts the speed control level according to the change of the real-time working current when the second level signal output by the main controller 150 remains unchanged, so as to adjust the real-time working current of the fan, that is, to keep the real-time working current unchanged. The speed feedback circuit 110 is connected to the fan and the main controller 150, and is used to obtain the speed information of the fan and send it to the main controller 150, so that the main controller 150 performs corresponding processing according to the speed information of the fan.

[0055] like Figure 2As shown, in one embodiment, the constant current control circuit 140 includes a first comparator U2B and a differential integration unit; the same-direction input end of the first comparator U2B is connected to the enable control circuit 140, the reverse input end of the first comparator is connected to the output end of the first comparator U2B, and the output end of the first comparator U2B is connected to the fan; the first end of the differential integration unit is connected to the current sampling circuit 130, the second end of the differential integration unit is connected to the main controller 150, and the third end of the differential integration unit is connected to the same-direction input end of the first comparator U2B. Specifically, the current change and the second level signal of the fan obtained by the current sampling circuit 130 unit are obtained through the differential integration unit, and the difference compensation is performed according to the current change, and the corresponding level signal, i.e., the third level signal, is output. The first comparator U2B forms a voltage follower. When the first level signal output by the main controller 150 is at a high level, the output of the enable control circuit 140 is at a low level. At this time, even if the differential integration unit outputs a third level signal, the output end of the first comparator U2B will output a low level according to the low level output by the enable control circuit 140, that is, the output of the third level signal is turned off. When the first level signal output by the main controller 150 is at a low level, the enable control power supply outputs a high level. At this time, the output end of the first comparator U2B will directly output the corresponding speed regulation level according to the input of the third level signal.

[0056] In one embodiment, the differential integration unit includes a second comparator U2A, a first capacitor C7, a first resistor R11, a second capacitor C6, a second resistor R6, a third resistor R10 and a third capacitor C5; the same-direction input end of the second comparator U2A is connected to the main controller 150 via the second resistor R6, the same-direction input end of the second comparator U2A is also connected to the ground via the third resistor R10 and the third capacitor C5 connected in parallel, the reverse input end of the second comparator U2A is connected to the current sampling circuit 130, the reverse input end of the second comparator U2A is also connected to the output end of the second comparator U2A via the first capacitor C7, and the output end of the second comparator U2A is grounded via the first resistor R11 and the second capacitor C6 connected in parallel. Specifically, the second level signal output by the main controller 150 is divided and filtered by the second resistor R6, the third resistor R10 and the third capacitor C5 to obtain a first voltage level, and the first voltage level is used as the input of the same-direction input end of the second comparator U2A. After the fan is working stably, the current sampling value obtained by its current sampling circuit 130 can be understood to correspond to the second voltage level, and the second voltage level is used as the input of the reverse input terminal of the second comparator U2A. The second comparator U2A compares the difference between the first voltage level and the second voltage level. When the first voltage level remains unchanged, it adjusts the speed control level of its output terminal by integrating and accumulating to adjust the real-time working current of the fan, and finally makes the second voltage level obtained by the current sampling circuit 130 equal to the first voltage level. The second capacitor C6 and the first resistor R11 rectify and filter the output signal of the output terminal of the second comparator U2A. In addition, in one embodiment, a resistor R7 is also set at the output terminal of the second comparator U2A. The resistor R7 is a current limiting resistor, which limits the output signal of the output terminal of the second comparator U2A. In another embodiment, the enable control circuit 140 is connected to the output end of the second comparator U2A. When the enable control circuit 140 outputs a high level, that is, when it conducts the speed regulation level output, when the third level signal output at the output end of the second comparator U2A is lower than 5V, the voltage at the same-direction input end of the first comparator U2A is directly equal to the third level signal. At this time, the voltage of the speed regulation level at the output end of the first comparator U2A is directly equal to the third level signal. When the third level signal output at the output end of the second comparator U2A is higher than or equal to 5V, the voltage at the same-direction input end of the first comparator U2A is equal to 5V. At this time, the voltage of the speed regulation level at the output end of the first comparator U2A is maintained at 5V. The third level signal of the fan interface is limited to within 5V, which is a general limit of fan manufacturers. In other embodiments, the limited voltage of the third level signal can be appropriately adjusted according to the actual design scheme.

[0057] In one embodiment, the current sampling circuit 130 includes a fourth resistor R8, a first end of the fourth resistor R8 is connected to the fan, a second end of the fourth resistor R8 is grounded, and a first end of the fourth resistor R8 is also connected to the reverse input end of the second comparator U2A. Specifically, the change of the working current of the fan is obtained through the fourth resistor R8, that is, when the internal working circuit of the fan changes, the corresponding resistance value inside it will change, and the voltage division generated on the fourth resistor R8 will also change at this time. The change is obtained through the second comparator U2A, and the change is compensated to eliminate the current change generated when the internal working circuit of the fan changes, so as to maintain the stability of the internal working circuit of the fan.

[0058] In one embodiment, the enabling control circuit 140 includes a first transistor Q2, a fourth capacitor C4 of a voltage stabilizing diode DZ1; the positive electrode of the voltage stabilizing diode DZ1 is connected to the same-direction input terminal of the first comparator U2B, the negative electrode of the voltage stabilizing diode DZ1 is grounded, the positive electrode of the voltage stabilizing diode DZ1 is also connected to the collector of the first transistor Q2, the emitter of the first transistor Q2 is grounded, and the base of the first transistor Q2 is connected to the main controller 150; the collector of the first transistor Q2 is also grounded via the fourth capacitor C4. Specifically, in the enabling control circuit 140, the first level signal output by the main controller 150 drives the first transistor Q2 to turn on or off. When the first level signal is at a high level, the high level drives the first transistor Q2 to turn on. At this time, the collector of the first transistor Q2 is grounded via the emitter, and its collector is at a low level. At this time, the same-direction input terminal of the first comparator U2B is at a low level, and the first comparator U2B outputs a low level, that is, the output of the speed regulation level is turned off. When the first level signal output by the main controller 150 is at a low level, the first transistor Q2 is turned off, and the collector voltage of the first transistor Q2 outputs a high level through the action of the voltage regulator diode DZ1. At this time, the same-direction input terminal of the first comparator U2B is at a high level, and the second comparator U2B outputs the speed control level input at its same-direction input terminal, that is, the output of the speed control level is turned on. The function of the voltage regulator diode DZ1 is to stabilize the voltage of the third level signal, and a voltage regulator diode with a voltage regulation value of about 5.1V can be selected.

[0059] In one embodiment, the speed feedback circuit 110 includes a second transistor Q1, a fifth resistor R4, a fifth capacitor C2, a sixth resistor R1, a seventh resistor R2 and a sixth capacitor C3; the base of the second transistor Q1 is connected to the fan, the collector of the second transistor Q1 is connected to a power supply via the sixth resistor R1, the collector of the second transistor Q1 is connected to one end of the seventh resistor R2, the other end of the seventh resistor R2 is connected to the main controller 150, the other end of the seventh resistor R2 is also grounded via the sixth capacitor C3, the collector of the second transistor Q1 is also grounded via the fifth resistor R4 and the fifth capacitor C2 connected in parallel, and the emitter of the second transistor Q1 is grounded. Specifically, the speed feedback of the fan interface will output a high and low level of a certain frequency corresponding to the speed when the fan is working normally, and after voltage division by the resistor R3 and the fifth resistor R4, it is used as a driving signal for the base of the second transistor Q1. When the second transistor Q1 is turned on, the main controller 150 receives a low level, and when the second transistor Q1 is turned off, the main controller 150 receives a high level provided by the power supply. The main controller 150 obtains the frequency information of the high and low levels by detecting the pulse width, and obtains the fan speed according to the frequency information.

[0060] In addition, a gas water heater of the present invention includes the DC fan control circuit described above. The gas water heater includes a DC fan and a DC fan control circuit connected to the DC fan. When the gas water heater is working, the DC fan control circuit controls the DC fan to cooperate with the action of gas combustion, thereby achieving safe use of the gas water heater.

[0061] In addition, Figure 3 As shown, a gas water heater wind pressure resistance control method of the present invention is applied to the gas water heater described above, and its control process includes: S1, confirming the working state of the internal heating working circuit, and when the working state is the heating state, obtaining the working current of the fan; S2, obtaining the preset fan speed corresponding to the working current of the fan according to the working current of the fan; S3, obtaining the real-time fan speed of the fan, and comparing the relationship between the real-time fan speed and the preset fan speed. If the real-time fan speed is greater than the preset fan speed, step S4 is executed; if the real-time fan speed is less than the preset fan speed, step S5 is executed; if the real-time fan speed is equal to the preset fan speed, step S6 is executed; S4, increasing the working current of the fan according to the first preset step, and obtaining the corresponding preset fan speed according to the new working current of the fan, and executing step S3; S5, reducing the working current of the fan according to the second preset step, and obtaining the corresponding preset fan speed according to the new working current of the fan, and executing step S3; S6, controlling the fan to work with the current working current.

[0062] Specifically, when the internal heating working circuit of the gas water heater is working, the corresponding working current is obtained. It can be understood that when the internal heating working circuit of the gas water heater is not working, the fan will not work either, and the internal control circuit can be in a non-working state at this time. Only when the gas water heater is heated, the internal control circuit starts to work. First, the working current of the fan is obtained through the current sampling circuit. The working current of the fan is the real-time working current of the fan, and the corresponding preset fan speed is obtained according to the working current. The preset fan speed corresponds to the preset fan speed corresponding to the working current of the fan under the condition of no wind pressure. The preset fan speed can be a preset range. At the same time, the real-time fan speed of the fan is obtained, and the real-time fan speed is compared with the preset fan speed. When the real-time fan speed is greater than the preset fan speed, the working current of the fan is increased according to the first preset component, and the corresponding preset fan speed is obtained again according to the new fan working current. At the same time, the real-time fan speed of the fan at this time is obtained, and compared to confirm whether the adjusted real-time fan speed meets the preset fan speed, so as to confirm whether further adjustment is needed. When the real-time fan speed is less than the preset fan speed, the fan operating current is reduced according to the second preset step, and the corresponding preset fan speed is obtained according to the new fan operating current. At the same time, the real-time fan speed of the fan at this time is obtained for comparison to confirm whether the adjusted real-time fan speed meets the preset fan speed. When the real-time fan speed meets the preset fan speed, that is, when it is equal to, the fan can be controlled to work according to the current operating current.

[0063] In a specific embodiment, the preset fan speed of the gas water heater is divided into three levels, each of which corresponds to a working current, that is, three working currents correspond to three preset fan speed ranges, and the corresponding relationship here can be understood as being obtained without external resistance or external wind pressure. When the gas water heater starts heating, the real-time working current of the fan is obtained, and the corresponding preset speed range is obtained according to the real-time working current, and the level of the preset speed range is judged. When the real-time fan speed range is less than the preset fan speed range, the working current is reduced to a lower level, the preset fan speed corresponding to the working current corresponding to the level is obtained, and the real-time fan speed of the fan when the working current corresponding to the level is obtained, and a comparison and confirmation is performed again. When the real-time fan speed range is greater than the preset fan speed range, the working current is increased to a higher level, the preset fan speed corresponding to the working current corresponding to the level is obtained, and the real-time fan speed of the fan when the working current corresponding to the level is obtained, and a comparison and confirmation is performed again. In another embodiment, it is specifically mentioned that if the current real-time fan current is 180mA, the corresponding fan speed when there is no external resistance is 200Hz. When the external resistance increases to the point where the real-time fan speed exceeds 220Hz, it is considered that the fan current needs to be increased, and S4 is executed. Then the preset fan speed is calculated based on the new fan current. Assuming that the current increases to 230mA at this time, the calculated preset fan speed without resistance is 270Hz. Because there is resistance at this time, the real-time speed must be between 280 and 300Hz to be considered normal operation. If the real-time speed is less than 280Hz, the fan current will be adjusted back to 180mA. If the real-time speed is greater than 300Hz, the fan current will be adjusted to 380mA.

[0064] like Figure 4 As shown, in one embodiment, a gas water heater wind pressure control method of the present invention further includes: S51, judging whether the preset fan speed is the minimum fan speed, if so, executing step S6, if not, executing step S5. Specifically, when the real-time fan speed is less than the preset fan speed, the preset fan speed can be judged first, if the preset fan speed corresponding to the current fan working current is the minimum fan speed, the fan working current will not be adjusted at this time, and the fan will be directly controlled to work according to the current working current. When the preset fan speed corresponding to the current fan working current is not the minimum fan speed, the fan working current can be reduced according to the second preset component to make the fan working level the level corresponding to the low current, and further confirmation is performed.

[0065] like Figure 5As shown, in one embodiment, a gas water heater wind pressure control method of the present invention also includes: S41, judging whether the preset fan speed is the maximum speed of the fan, if so, executing step S7, if not, executing step S4; S7, closing the heating circuit of the water heater and / or generating an excessive wind pressure alarm. Specifically, when the real-time fan speed is greater than the preset fan speed, the preset fan speed can be judged first. If the preset fan speed corresponding to the current fan working current is the maximum speed of the fan, the fan working current will not be adjusted at this time, because the adjustment at this time will exceed the upper limit of the fan working current, which will bring risks. At this time, the heating circuit of the water heater can be directly closed, and an excessive wind pressure alarm can also be generated for warning prompts. If the preset fan speed is not the maximum speed of the fan, the fan working current can be adjusted according to the first preset step, so that the fan working level is the level corresponding to the increased current, and further confirmation is performed.

[0066] In one embodiment, a method for controlling wind pressure resistance of a gas water heater of the present invention further includes: obtaining the working level of the fan according to the working current of the fan, and obtaining the corresponding first preset step or second preset step according to the working level. Specifically, after obtaining the real-time working current of the fan, the working level of the fan can be confirmed according to the working current, for example, three preset levels are set, and the working current corresponding to each preset level is set with a time limit, and the step with other working levels is set at each working level, for example, when the working current is reduced from the second working level to the first working level, it is reduced according to the second preset step, and when the working current is increased from the second working level to the third working level, it is increased according to the first preset step.

[0067] Further, the first preset step is equal or unequal; or the second preset step is equal or unequal. Specifically, when setting the preset step of current increase, the preset step can be increased according to equal values, it can also be based on the current working current, which can also be understood as related to the current working level. It can set the first preset step according to the current working current. For example, when increasing the working current from the first working level to the second working level, it increases according to the percentage of the working current of the first working level, such as 10%. When increasing the working current from the second working level to the third working level, it increases according to the percentage of the working current of the second working level, such as 10%. Similarly, the second preset step can be set in a similar manner during the process of reducing the working current.

[0068] A wind pressure resistance control system for a gas water heater of the present invention comprises:

[0069] A first determination unit 610 is used to determine the working state of the internal heating working circuit;

[0070] A first acquisition unit 620, used for acquiring the working current of the fan when the working state is a heating state;

[0071] A second acquisition unit 630 is used to acquire a preset fan speed corresponding to the working current of the fan according to the working current of the fan;

[0072] The third acquisition unit 640 is used to acquire the real-time fan speed of the fan;

[0073] The second judgment unit 650 is used to compare the relationship between the real-time fan speed and the preset fan speed;

[0074] The first execution unit 661 is used to increase the working current of the fan according to a first preset step when the real-time fan speed is greater than the preset fan speed;

[0075] The second execution unit 662 is used to reduce the working current of the fan according to a second preset step when the real-time fan speed is less than the preset fan speed;

[0076] The third execution unit 663 is used to control the fan to operate at the current operating current when the real-time fan speed is equal to the preset fan speed.

[0077] Specifically, the specific coordination operation process between the various units of the anti-wind pressure control system of a gas water heater here can refer to the above-mentioned anti-wind pressure control method of a gas water heater, which will not be repeated here.

[0078] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A DC fan control circuit, characterized in that: include: A main controller (150) for outputting a first level signal and a second level signal; A speed feedback circuit (110) connected to the fan and the main controller (150) and used for acquiring speed information of the fan and sending the speed information to the main controller (150); A current sampling circuit (130) connected to the fan and used to obtain the real-time working current of the fan; A constant current control circuit (120) connected to the fan, the current sampling circuit (130) and the main controller (150), configured to receive the second level signal and, when the second level signal remains unchanged, output a speed adjustment level to maintain the real-time working current unchanged; An enabling control circuit (140) connected to the constant current control circuit (120) and the main controller (150) and used for receiving the first level signal to turn on or off the speed regulation level output according to the first level signal; The constant current control circuit (120) comprises a first comparator (U2B) and a differential integration unit; The same-direction input end of the first comparator (U2B) is connected to the enabling control circuit (140), the reverse input end of the first comparator is connected to the output end of the first comparator (U2B), and the output end of the first comparator (U2B) is connected to the fan; A first end of the differential integration unit is connected to the current sampling circuit (130), a second end of the differential integration unit is connected to the main controller (150), and a third end of the differential integration unit is connected to the non-inverting input end of the first comparator (U2B); The speed feedback circuit (110) comprises a second transistor (Q1), a fifth resistor (R4), a fifth capacitor (C2), a sixth resistor (R1), a seventh resistor (R2) and a sixth capacitor (C3); The base of the second transistor (Q1) is connected to the fan, the collector of the second transistor (Q1) is connected to a power supply via the sixth resistor (R1), the collector of the second transistor (Q1) is connected to one end of the seventh resistor (R2), the other end of the seventh resistor (R2) is connected to the main controller (150), the other end of the seventh resistor (R2) is also grounded via the sixth capacitor (C3), the collector of the second transistor (Q1) is also grounded via the fifth resistor (R4) and the fifth capacitor (C2) connected in parallel, and the emitter of the second transistor (Q1) is grounded.

2. The DC fan control circuit according to claim 1, characterized in that: The differential integration unit includes a second comparator (U2A), a first capacitor (C7), a first resistor (R11), a second capacitor (C6), a second resistor (R6), a third resistor (R10) and a third capacitor (C5); The same-direction input end of the second comparator (U2A) is connected to the main controller (150) via the second resistor (R6), the same-direction input end of the second comparator (U2A) is also grounded via the third resistor (R10) and the third capacitor (C5) connected in parallel, the reverse input end of the second comparator (U2A) is connected to the current sampling circuit (130), the reverse input end of the second comparator (U2A) is also connected to the output end of the second comparator (U2A) via the first capacitor (C7), and the output end of the second comparator (U2A) is grounded via the first resistor (R11) and the second capacitor (C6) connected in parallel.

3. The DC fan control circuit according to claim 2, characterized in that: The current sampling circuit (130) comprises a fourth resistor (R8), a first end of the fourth resistor (R8) being connected to the fan, a second end of the fourth resistor (R8) being grounded, and a first end of the fourth resistor (R8) being also connected to a reverse input end of a second comparator (U2A).

4. The DC fan control circuit according to claim 1, characterized in that: The enabling control circuit (140) comprises a first transistor (Q2), a voltage stabilizing diode (DZ1) and a fourth capacitor (C4); The positive electrode of the voltage zener diode (DZ1) is connected to the non-inverting input terminal of the first comparator (U2B), the negative electrode of the voltage zener diode (DZ1) is grounded, the positive electrode of the voltage zener diode (DZ1) is also connected to the collector of the first transistor (Q2), the emitter of the first transistor (Q2) is grounded, and the base of the first transistor (Q2) is connected to the main controller (150); the collector of the first transistor (Q2) is also grounded via the fourth capacitor (C4).

5. A gas water heater, characterized in that: It comprises a DC fan control circuit as described in any one of claims 1 to 4.

6. A method for controlling wind pressure resistance of a gas water heater, characterized in that: The gas water heater as claimed in claim 5 comprises: S1. confirming the working state of the internal heating working circuit, and obtaining the working current of the fan when the working state is a heating state; S2. acquiring a preset fan speed corresponding to the working current of the fan according to the working current of the fan; S3, obtaining the real-time fan speed of the fan, and comparing the real-time fan speed with the preset fan speed. If the real-time fan speed is greater than the preset fan speed, executing step S4; if the real-time fan speed is less than the preset fan speed, executing step S5; if the real-time fan speed is equal to the preset fan speed, executing step S6; S4, increasing the operating current of the fan according to the first preset step, and obtaining the corresponding preset fan speed according to the new operating current of the fan, and executing step S3; S5, reducing the operating current of the fan according to a second preset step, and obtaining a corresponding preset fan speed according to the new operating current of the fan, and executing step S3; S6. Control the fan to operate at the current operating current.

7. The method for controlling wind pressure resistance of a gas water heater according to claim 6, characterized in that: The method further comprises: S51, determining whether the preset fan speed is the minimum fan speed, if so, executing step S6, if not, executing step S5.

8. The method for controlling wind pressure resistance of a gas water heater according to claim 7, characterized in that: The method further comprises: S41, determining whether the preset fan speed is the maximum fan speed, if yes, executing step S7, if no, executing step S4; S7: Turn off the heating circuit of the water heater and / or generate an excessive wind pressure alarm.

9. The method for controlling wind pressure resistance of a gas water heater according to claim 6, characterized in that: The method further comprises: The operating level of the fan is acquired according to the operating current of the fan, and the corresponding first preset step or second preset step is acquired according to the operating level.

10. The method for controlling wind pressure resistance of a gas water heater according to claim 9, characterized in that: The first preset steps are equal or unequal; or the second preset steps are equal or unequal.

11. A gas water heater wind pressure resistance control system, characterized in that: Applied to the gas water heater according to claim 5, the control system comprises: A first judging unit, used to confirm the working state of the internal heating working circuit; A first acquisition unit, used for acquiring the working current of the fan when the working state is a heating state; A second acquisition unit, configured to acquire a preset fan speed corresponding to the working current of the fan according to the working current of the fan; A third acquisition unit, used to acquire the real-time fan speed of the fan; A second judgment unit, used for comparing the relationship between the real-time fan speed and the preset fan speed; A first execution unit, configured to increase the operating current of the fan according to a first preset step when the real-time fan speed is greater than the preset fan speed; A second execution unit, configured to reduce the operating current of the fan according to a second preset step when the real-time fan speed is less than the preset fan speed; The third execution unit is used to control the fan to operate at a current operating current when the real-time fan speed is equal to the preset fan speed.

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