Digital ignition and flame detection integrated circuit

Abstract

The application provides a digital ignition and flame detection integrated circuit, comprising: an ignition request input end, a driving control module, a voltage boosting module, an ignition circuit, a trigger discharge module, a flame detection circuit and a flame condition output end; the driving control module is connected with the ignition request input end and the flame condition output end respectively; the output end of the driving control module is electrically connected with the input end of the voltage boosting module, the ignition circuit and the flame detection circuit respectively; the output end of the voltage boosting module is electrically connected with the ignition circuit and the flame detection circuit respectively; the ignition circuit feeds back the change of a first voltage signal caused by charging of the voltage boosting module and discharge of the trigger discharge module to the driving control module; and the flame detection circuit feeds back the change of a second voltage signal caused by charging of the voltage boosting module and load discharge to the driving control module. The ignition and flame detection effect of the application is good, and the safety and reliability are high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame detection, and in particular to a digital ignition and flame detection integrated circuit. BACKGROUND

[0002] Currently, there are three main flame detection technologies. One is the light sensing technology based on ultraviolet light or infrared light recognition commonly used in industrial boilers. Two is the heat sensing technology based on thermocouples commonly used in household gas stoves. Three is the ion flame detection technology based on ion current recognition commonly used in household gas water heaters. Generally speaking, ultraviolet light recognition requires sensors with high cost and short life, and is easily affected by ambient light, such as the ultraviolet light emitted by the electric arc used to ignite flammable gas, so it is generally not used in household products. The heat sensing technology has a reaction time of more than 10 seconds due to residual heat, and can only be used in products with low safety requirements. In recent years, many integrated cookers and gas stove brands have launched products based on ion flame detection technology, which shows the importance of this technology in household gas appliances.

[0003] The existing household ion flame detection circuit basically adopts an analog circuit scheme. Its core is to generate an alternating current output with a frequency of 20 kHz or more, a positive half wave as an approximate sine wave and a negative half wave as a square wave, for flame detection, through a boost transformer with a feedback winding in a self-oscillating manner. However, the above household ion flame detection circuit can only output a fire or no fire signal, is easily affected by the precision of analog circuit components, has low flame detection sensitivity consistency, and when combined with a household pulse ignition circuit, the inconsistent requirements of the flame detection and ignition circuits for circuit parameters can also cause the flame detection function to fail, with low reliability and poor safety.

[0004] The existing industrial ion flame detection circuit generally uses a switching type voltage stabilizing chip (such as MC32063A) to construct a Boost type boost conversion circuit to achieve stable voltage output of high voltage, and then generates a 50 Hz or 60 Hz alternating square wave output through a coupling capacitor and a square wave generation circuit for flame detection. Since the alternating square wave generated by the industrial ion flame detection circuit is very stable, there is no problem of low flame detection sensitivity consistency in household ion flame detection circuits, and the flame signal can also be converted into an analog signal of 0 to 5 V for fire indication or adaptive control. However, the above industrial flame detection circuit has many components, a complex circuit, high cost, low reliability, and a low frequency of alternating square wave, which requires a coupling capacitor and a filter capacitor with large capacity, high cost, and large PCB space. SUMMARY

[0005] In view of the above related technical problems, the present application provides a digital ignition and flame detection integrated circuit with good ignition and flame detection effect, low cost, high safety and reliability.

[0006] To solve the above technical problems, the embodiment of the present application provides a digital ignition and flame detection integrated circuit, comprising: an ignition request input end, a driving control module, a voltage boosting module, a trigger discharge module, an ignition circuit, a flame detection circuit and a flame condition output end, wherein the driving control module is connected to the ignition request input end and the flame condition output end respectively;

[0007] The output end of the driving control module is electrically connected to the input end of the voltage boosting module, the input end of the trigger discharge module and the flame detection circuit respectively; the output end of the trigger discharge module is connected to the input end of the ignition circuit, the output end of the voltage boosting module is electrically connected to the ignition circuit and the flame detection circuit respectively, the driving control module outputs a first pulse signal to the input end of the voltage boosting module, the driving control module outputs a trigger signal according to the ignition request and outputs the trigger signal to the input end of the ignition circuit through the trigger discharge module, the ignition circuit feeds back the change of a first voltage signal caused by charging of the voltage boosting module and discharging of the trigger discharge module to the driving control module, the flame detection circuit feeds back the change of a second voltage signal caused by charging of the voltage boosting module and discharging of the load to the driving control module, the driving control module outputs a second pulse signal to the input end of the flame detection circuit, the flame detection circuit feeds back the change of a flame signal voltage caused by an external flame to the driving control module, and the driving control module outputs a result of having flame or no flame from the flame condition output end after logical judgment according to the size of the flame signal voltage, the current system state and the result of fault self-checking.

[0008] Preferably, the flame detection circuit comprises: a high-voltage stabilizing module, a second voltage collecting module, an alternating square wave module and a signal rectifying module; the input end of the high-voltage stabilizing module is connected to the output end of the voltage boosting module, the first output end of the high-voltage stabilizing module is connected to the input end of the second voltage collecting module, the output end of the second voltage collecting module is connected to the driving control module, for outputting the second voltage signal collected by the second voltage collecting module to the driving control module; the second output end of the high-voltage stabilizing module is connected to the input end of the alternating square wave module, the input end of the alternating square wave module is connected to the driving control module, for receiving the second pulse signal output by the driving control module, the output end of the alternating square wave module is connected to the input end of the signal rectifying module, and the output end of the signal rectifying module is connected to the driving control module, for feeding back the flame signal output by the signal rectifying module to the driving control module.

[0009] Preferably, the drive control module is provided with a first algorithm unit, a second algorithm unit, an ignition signal detection unit, a fault self-checking unit and a flame signal processing unit, the first algorithm unit is used to adjust the duty cycle of the pulse signal in real time according to the first voltage signal, the second algorithm unit is used to adjust the duty cycle of the pulse signal in real time according to the second voltage signal; the ignition signal detection unit is used to detect the ignition signal, the fault self-checking unit is used to realize the boost self-checking, the period self-checking and the flame induction line grounding self-checking; the flame signal processing unit is used to process the flame signal.

[0010] Preferably, the working frequency of the second algorithm unit is 1 / 4 times of the working frequency of the first algorithm unit.

[0011] Preferably, the digital ignition and flame detection integrated circuit further comprises a power supply control module, the power supply control module is electrically connected with the drive control module and the boost module respectively, and the power supply control module is used to receive the driving signal output by the drive control module and supply power for the boost module.

[0012] Preferably, the digital ignition and flame detection integrated circuit further comprises an overcurrent detection module and an automatic power-off module, the output end of the overcurrent detection module is connected with the input end of the power supply control module, the input end of the automatic power-off module and the input end of the drive control module respectively, and the overcurrent detection module is used to output a test signal to the drive control module; the automatic power-off module is electrically connected with the power supply control module, and is used to realize automatic power-off through the test signal output by the overcurrent detection module.

[0013] Preferably, the digital ignition and flame detection integrated circuit further comprises a step-down voltage stabilizing module, the input end of the step-down voltage stabilizing module is electrically connected with a power supply, the output end of the step-down voltage stabilizing module is electrically connected with the power supply input end of the drive control module, and the step-down voltage stabilizing module is used to supply power for the drive control module after reducing the voltage of the power supply.

[0014] Preferably, the drive control module is a microcontroller MCU, and the microcontroller is an 8-bit MCU with an 8MHz or 16MHz internal clock.

[0015] Compared with the related art, the application connects the driving control module to the ignition request input end and the flame condition output end respectively, so as to conveniently connect external devices to realize the ignition and flame detection functions with good effect; the application can also be embedded into the existing control system as a functional module; the output end of the driving control module is electrically connected to the input end of the voltage boosting module, the input end of the trigger discharge module and the fire detection circuit; the output end of the trigger discharge module is connected to the input end of the ignition circuit; the driving control module outputs a first pulse signal to the input end of the voltage boosting module; the ignition circuit feeds back the change of the first voltage signal caused by the charging of the voltage boosting module and the discharge of the trigger discharge module to the driving control module; the fire detection circuit feeds back the change of the second voltage signal caused by the charging of the voltage boosting module and the discharge of the load to the driving control module; the driving control module outputs a second pulse signal to the input end of the fire detection circuit; the fire detection circuit feeds back the change of the flame signal voltage caused by the external flame to the driving control module; the driving control module outputs the result of having fire or no fire from the flame condition output end after logical judgment according to the size of the flame signal voltage, the current system state and the result of the fault self-check. The consistency of the ignition and fire detection performance is ensured by using the digital chip control technology, and the wide application of the high-performance ignition and fire detection configuration makes the application more adaptable, and the manufacturer does not need to debug on site; meanwhile, the application realizes the sharing of the voltage boosting module and the high frequency of the alternating square wave, effectively reduces the component cost and improves the reliability of the circuit; and the digital chip control technology realizes the software and hardware fault self-check, further improving the reliability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application will be understood more clearly and more easily understood by the following detailed description in combination with the accompanying drawings. In the drawings:

[0017] Figure 1 The module diagram of the digital ignition and fire detection integrated circuit of the application;

[0018] Figure 2 The module diagram of the driving control module of the application;

[0019] Figure 3 The module diagram of the fault self-check unit of the application;

[0020] Figure 4 The control timing when the ignition request is detected.

[0021] In the figure, 1, drive control module, 11, first algorithm unit, 12, second algorithm unit, 13, ignition signal detection unit, 14, fault self-checking unit, 141, boost self-checking, 142, period self-checking, 143, flame sensing wire ground self-checking, 15, flame signal processing unit; 2, boost module, 3, ignition circuit, 31, ignition module, 32, first voltage acquisition module, 4, fire detection circuit, 41, high-voltage stabilizing module, 42, second voltage acquisition module, 43, alternating square wave module, 44, signal rectifier module, 5, power supply control module, 6, automatic power-off module, 7, voltage reduction stabilizing module, 8, overcurrent detection module, 9, trigger discharge module. DETAILED DESCRIPTION

[0022] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0023] The specific embodiments / examples described herein are specific embodiments of the present application, used to illustrate the concept of the present application, and are explanatory and exemplary, and should not be interpreted as limiting the embodiments of the present application and the scope of the present application. In addition to the examples described herein, those skilled in the art can also employ other technical solutions based on the content disclosed in the claims and the specification of the present application, which include technical solutions that make any obvious substitutions and modifications to the examples described herein, and these technical solutions are within the protection scope of the present application.

[0024] As shown in Figures 1-4 The present application provides a digital ignition and flame detection integrated circuit, which comprises an ignition request input end Igni, a drive control module 1, a boost module 2, an ignition circuit 3, a trigger discharge module 9, a fire detection circuit 4, and a flame condition output end FSout, wherein the drive control module 1 is connected to the ignition request input end and the flame condition output end FSout respectively.

[0025] The output end of the drive control module 1 is electrically connected with the input end of the voltage boosting module 2, the trigger discharge module 9 and the flame detection circuit respectively; the output end of the trigger discharge module 9 is connected with the input end of the ignition circuit 3, the output end of the voltage boosting module 2 is electrically connected with the ignition circuit 3 and the flame detection circuit 4 respectively, the drive control module 1 outputs the first pulse signal PWM1 to the input end of the voltage boosting module 2, the drive control module 1 outputs the trigger signal according to the ignition request and outputs to the input end of the ignition circuit 3 through the trigger discharge module 9, the ignition circuit 3 feeds back the change of the first voltage signal caused by the voltage boosting module 2 to the drive control module 1; the flame detection circuit 4 feeds back the change of the second voltage signal caused by the voltage boosting module 2 to the drive control module 1, the drive control module 1 outputs the second pulse signal to the input end of the flame detection circuit 4, the flame detection circuit 4 feeds back the change of the flame signal voltage caused by the external flame to the drive control module 1, the drive control module 1 outputs the result of having flame or not having flame from the flame condition output end after the logical judgment according to the size of the flame signal voltage, the current system state and the result of the fault self-checking.

[0026] In the embodiment, the drive control module 1 is provided with a first algorithm unit 11, a second algorithm unit 12, an ignition signal detection unit 13, a fault self-checking unit 14 and a flame signal processing unit 15, the first algorithm unit 11 is used for adjusting the duty cycle of the pulse signal according to the first voltage signal in real time, the second algorithm unit 12 is used for adjusting the duty cycle of the pulse signal according to the second voltage signal; the ignition signal detection unit 13 is used for detecting the ignition signal, the fault self-checking unit 14 is used for realizing the voltage boosting self-checking, the period self-checking and the flame induction line grounding self-checking; the flame signal processing unit 15 is used for obtaining the result of whether the flame exists according to the flame signal voltage value, the current system state and the output of the fault self-checking.

[0027] Specifically, the first algorithm unit 11 uses high duty cycle to perform fast charging on the CBB capacitor during the system power-on period and after discharging, the second algorithm unit 12 uses low duty cycle to maintain the stability of the high-voltage electrolytic capacitor voltage. The two algorithms will have a switching process, because the fast charging time is very short and the capacity of the high-voltage electrolytic capacitor is large, so the algorithm switching will not affect the voltage stabilization, note that the voltage stable AC square wave is stable, and the flame detection is stable.

[0028] Specifically, during the ignition request invalid period, the fault self-checking unit 14 will perform a periodic self-check to ensure the reliability of the flame detection system, and also identify whether the induction line is grounded. When the upper system issues an ignition request to the drive control module 1 through the ignition request input end Igni and the ignition signal detection unit 13 identifies a valid ignition request, the drive control module 1 implements a single discharge by outputting a Trig signal to the trigger discharge module 9. Then, the first algorithm unit 11 adjusts the duty cycle of the PWM1 signal in real time according to the Volt1 signal fed back by the first voltage collection module 32 and outputs it to the boost module 2 to quickly charge the CBB capacitor of the ignition module 31 until the CBB capacitor is charged to a first preset voltage value. Then, the second algorithm unit 12 adjusts the duty cycle of the PWM1 signal in real time according to the Volt2 signal fed back by the second voltage collection module 42 and outputs it to the boost module 2 to stabilize the voltage of the electrolytic capacitor of the high-voltage stabilizing module 41 to a second preset voltage value. During the ignition request valid period, the process of discharge, fast charging, and voltage stabilization is repeated in each ignition cycle, and the fault self-checking unit 14 performs a boost self-check in each ignition cycle to ensure the reliability of the ignition system. During both the ignition request valid and invalid periods, the drive control module 1 outputs a PWM2 signal to the alternating square wave module 43 to generate an alternating square wave signal for flame detection. The flame signal processing unit 15 generates a result of having fire or no fire according to the FSin signal fed back by the signal rectification module 44, the current system state, and the output of the fault self-checking unit 14, and feeds back the result to the upper system through the flame condition output end FSout. Therefore, the upper system only needs two communication lines to complete the ignition and flame detection tasks. In addition, the drive control module 1 can upload the current system state, fault code, and other information to the upper system in a digital communication manner through the flame condition output end FSout. In this way, the use of digital chip control technology ensures the consistency of the ignition and flame detection performance, and the high-performance ignition and flame detection configuration makes the application more widely, and when applied to a full-premixed gas wall-hanging stove product, the adaptability is basically achieved, and the manufacturer does not need to debug on site. At the same time, the invention realizes the sharing of the boost module 2 and the high frequency of the alternating square wave, effectively reduces the component cost and improves the reliability of the circuit; and the digital chip control technology realizes the software and hardware fault self-checking, which further improves the reliability of the product.

[0029] The drive control module 1 also has the automatic voltage stabilizing function of the boost type DC-DC power supply control chip circuit scheme. This makes the drive control module 1 and the boost module 2 can form a digital pulse ignition circuit with the ignition circuit 3, and can form a digital flame detection circuit with the flame detection circuit 4.

[0030] Optionally, the digital ignition and flame detection integrated circuit can be a functional unit of the upper system, or can be a separate flame sensor. Through the driving control module 1, the flame signal voltage value fed back by the flame detection circuit 4, the current system state and the result of the fault self-check are comprehensively logically judged to generate a result FSout of the presence or absence of flame, and then output to the upper system to realize the function of flame detection.

[0031] In this embodiment, the fault self-check unit 14 includes three sub-modules, namely, boost self-check 141, cycle self-check 142 and flame sensing line ground self-check 143. Among them, the boost self-check 141 is used to cooperate with the ignition function to monitor whether the boost module 2, the ignition circuit 3 and the flame detection circuit 4 have circuit abnormalities such as component failure and component parameter abnormalities in real time. Once a circuit abnormality occurs and the fault persists, the boost self-check 141 will generate a fault code and make the driving control module 1 exit the ignition mode. The cycle self-check 142 is used to cooperate with the flame detection function to periodically monitor whether the flame detection circuit 4 has a circuit abnormality such as component failure. Once a circuit abnormality occurs, the cycle self-check 142 will generate a fault code and output a result of no flame through the flame condition output end. Specifically, the cycle self-check 142 will execute different self-check strategies according to the flame signal voltage value FSin. When FSin is greater than a certain value, the self-check strategy will temporarily adjust the duty ratio of PWM2 to 100%, which is equivalent to stopping the vibration and making the coupling capacitor of the alternating square wave module 43 discharge quickly. The self-check strategy will track the change of FSin in real time after stopping the vibration. With the discharge of the coupling capacitor, FSin should decrease quickly. When FSin decreases to a certain value, the self-check strategy will restore the duty ratio of PWM2, which is equivalent to restarting the vibration. If FSin does not decrease quickly during the stopping of the vibration, the flame detection circuit 4 must have a circuit abnormality. Conversely, when FSin is less than a certain value, the self-check strategy will temporarily adjust the duty ratio of PWM2 to 0%, which is equivalent to stopping the vibration and making the coupling capacitor of the alternating square wave module 43 charge quickly. The self-check strategy will track the change of FSin in real time after stopping the vibration. With the charging of the coupling capacitor, FSin should increase quickly. When FSin increases to a certain value, the self-check strategy will restore the duty ratio of PWM2, which is equivalent to restarting the vibration. If FSin does not increase quickly during the stopping of the vibration, the flame detection circuit 4 must have a circuit abnormality. If the flame detection circuit 4 is normal and the flame signal voltage value FSin is greater than a certain value, the flame sensing line ground self-check 143 will be put into operation. During the execution of the cycle self-check 142, the FSin data will be collected and counted within a certain time after the restoration of the duty ratio of PWM2. If the flame sensing line is not connected to the flame sensing needle due to various reasons such as disconnection and the exposed end of the connecting line touches the shell, the flame sensing line ground self-check 143 will collect abnormal data greater than the normal value. When the abnormal data is greater than a certain value, the flame sensing line ground self-check 143 will generate a fault code and output a result of no flame through the flame condition output end.

[0032] In the embodiment, the ignition circuit 3 comprises an ignition module 31 and a first voltage acquisition module 32, a first input end of the ignition module 31 is connected with an output end of the boost module 2, a second input end of the ignition module 31 is connected with an output end of the trigger discharge module 9, an input end of the trigger discharge module 9 is connected with an output end of the drive control module 1, for receiving a trigger signal Trig outputted by the drive control module 1, an output end of the ignition module 31 is connected with an input end of the first voltage acquisition module 32, and an output end of the first voltage acquisition module 32 is connected with the drive control module 1, for outputting a first voltage signal Volt1 acquired by the first voltage acquisition module 32 to the drive control module 1.

[0033] In the embodiment, the ignition circuit 3 comprises an ignition module 31 and a first voltage acquisition module 32, a first input end of the ignition module 31 is connected with an output end of the boost module 2, a second input end of the ignition module 31 is connected with an output end of the trigger discharge module 9, an input end of the trigger discharge module 9 is connected with an output end of the drive control module 1, for receiving a trigger signal Trig outputted by the drive control module 1, an output end of the ignition module 31 is connected with an input end of the first voltage acquisition module 32, and an output end of the first voltage acquisition module 32 is connected with the drive control module 1, for outputting a first voltage signal Volt1 acquired by the first voltage acquisition module 32 to the drive control module 1.

[0034] Specifically, the trigger signal outputted by the drive control module 1 controls the ignition module 31 to discharge. During the power-on of the upper system, the drive control module 1 outputs a PWM1 signal to the boost module 2, and the boost module 2 charges the ignition module 31 and the high-voltage stabilizing module 41, the drive control module 1 outputs a PWM2 signal to the alternating square wave module 43, the alternating square wave module 43 generates an alternating square wave signal for flame detection, the signal rectification module 44 feeds back a flame signal FSin to the flame signal processing unit 15 of the drive control module 1, the flame signal processing unit 15 comprehensively generates a result of having flame or not having flame according to the current system state and the output of the fault self-checking unit 14, and feeds back the result to the upper system through a flame condition output end FSout, so as to realize the control of ignition and flame detection together.

[0035] Specifically, the AC square wave module 43 is powered by the high-voltage stabilizing module 41 and converts the PWM2 signal output by the driving control module 1 into a high-voltage AC square wave signal, which is output through a flame sensing wire and a sensing needle for detecting a flame, and at the same time, the high-voltage AC square wave signal is also output to the signal rectifying module 44, thereby forming a flame signal FSin signal that can be detected by the driving control module 1.

[0036] In this embodiment, the working frequency of the second algorithm unit 12 is 1 / 4 of the working frequency of the first algorithm unit 11.

[0037] In this embodiment, the digital ignition and flame detection integrated circuit further comprises a power supply control module 5, which is electrically connected with the driving control module 1 and the voltage boosting module 2 respectively, and is used for receiving the driving signal output by the driving control module 1 and supplying power to the voltage boosting module 2.

[0038] In this embodiment, the digital ignition and flame detection integrated circuit further comprises an overcurrent detection module 8 and an automatic power-off module 6, the output end of the overcurrent detection module 8 is connected with the input end of the power supply control module 5, the input end of the automatic power-off module 6 and the input end of the driving control module 1 respectively, and the overcurrent detection module 8 is used for outputting a test signal to the driving control module 1. The overcurrent detection module 8 detects the current signal passing through the input power supply and sends the current signal to the automatic power-off module 6, and when the current signal exceeds the set current size, the automatic power-off module 6 sends a control signal to the power supply control module 5 to realize automatic power-off, and the power supply module 5 has good control effect and the overall circuit has high safety. At the same time, in order to improve the conversion efficiency of the voltage boosting module 2, the higher the voltage of the input power supply of the overcurrent detection module 8 is, the better.

[0039] In this embodiment, the digital ignition and flame detection integrated circuit further comprises a voltage reducing and stabilizing module 7, the input end of the voltage reducing and stabilizing module 7 is electrically connected with a power supply, the output end of the voltage reducing and stabilizing module 7 is electrically connected with the power supply input end of the driving control module 1, and the voltage reducing and stabilizing module 7 is used for reducing the voltage of the power supply and supplying power to the driving control module 1. The present application can support common 12V and 24V input, and can also support common 30V input of gas appliances, and only needs to fine-tune the algorithm unit one inside the driving control module 1 when the input is different. When the system does not have a separate 5V power supply to supply power to the driving control module 1, 5V power supply can be obtained through the voltage reducing and stabilizing module 7.

[0040] In this embodiment, the driving control module 1 is a microcontroller MCU, and the microcontroller is an 8-bit MCU with an internal clock of 8MHz or 16MHz.

[0041] The working principle of the present application is as follows:

[0042] After power-on, the drive control module 1 first allows the system to enter the self-checking stage, and through the internal ADC peripheral, the drive control module 1 performs real-time sampling conversion on the Volt1 signal output by the first voltage collection module 32 at a conversion rate of 31.25 kHz or above. The Volt1 signal reflects the voltage of the CBB capacitor in the ignition module 31. If the Volt1 signal is higher than a certain value, it means that the power supply control module 5 may have an abnormality, such as a short circuit of the field effect transistor controlling the power supply, and the starting process will be interrupted. Conversely, the drive control module 1 will output an effective Power signal to control the power supply control module 5 to turn on the power input. After turning on the power input, the drive control module 1 will continue to check the Volt1 signal. If the Volt1 signal voltage is too low, it means that the power supply control module 5 may have an abnormality, such as an open circuit of the field effect transistor controlling the power supply. If the Volt1 signal voltage is too high, it means that the voltage of the power input is too high, and when the Volt1 signal voltage is unreasonable, the starting process will be interrupted. Conversely, the drive control module 1 will allow the system to enter the fast charging stage, and through the self-contained PWM peripheral, the drive control module 1 outputs a PWM1 signal at a working frequency of 31.25 kHz or above. The PWM1 signal will control the boost module 2 to supply power to the ignition module 31 and the high-voltage stabilizing module 41. Among them, supplying power to the ignition module 31 will increase the voltage of its CBB capacitor, and supplying power to the high-voltage stabilizing module 41 will increase the voltage of its high-voltage electrolytic capacitor. Since the boost module 2 is a high-frequency switching circuit and is controlled by the drive control module 1, the charging current provided by the boost module 2 in each working period is controlled, and the increase in capacitor voltage in each working period is also controlled. During the fast charging process, the voltage of the CBB capacitor will be consistent with the voltage of the high-voltage electrolytic capacitor.

[0043] After entering the fast charging stage, the first algorithm unit 11 in the drive control module 1 adjusts the duty cycle of the PWM1 signal in real time according to the Volt1 signal, ensuring that the peak current flowing through the inductor during energy storage does not exceed the rated use condition, and the boost module 2 charges the CBB capacitor to the first target voltage value at the fastest speed. Because the shorter the charging time, the higher the ignition frequency can be. However, in order to prevent the high-voltage electrolytic capacitor in the high-voltage stabilizing module 41 from being overcharged, when the voltage of the CBB capacitor approaches the first target voltage value, the first algorithm unit 11 gradually reduces the duty cycle of the PWM1 signal, so that the voltage of the CBB capacitor reaches the first target voltage value smoothly.

[0044] After entering the fast charging stage, the drive control module 1 will also monitor the charging speed of the CBB capacitor. Since the total capacitance of the capacitive load of the ignition module 31 and the high-voltage stabilizing module 41 is known, and the charging current is controlled, the time required to charge the CBB capacitor to the first target voltage value is predictable. When the charging speed is abnormal, such as when the CBB capacitor capacity decreases due to aging, the charging speed will increase, and when the input voltage is too low, the charging speed will slow down. At this time, the drive control module 1 will give a system prompt, such as through a digital screen display or through a communication protocol to inform the upper system. In addition, if the CBB capacitor voltage does not increase for a long time, it means that the boost module 2 is abnormal, such as the control energy storage switch tube is open circuit, the start process will be interrupted, otherwise, when the CBB capacitor is charged to the first target voltage value, the drive control module 1 will make the system enter the stabilizing stage.

[0045] After entering the stabilizing stage, the ADC peripheral inside the drive control module 1 will change its input channel and instead sample and convert the Volt2 signal output by the second voltage sampling module 42 in real time. Volt2 reflects the voltage of the high-voltage electrolytic capacitor inside the high-voltage stabilizing module 41. The second algorithm unit 12 inside the drive control module 1 will adjust the duty cycle of the PWM1 signal in real time according to the Volt2 signal to control the boost module 2 to slowly charge the CBB capacitor and the high-voltage electrolytic capacitor, so as to ensure that the voltage of the high-voltage electrolytic capacitor is stabilized at the second target voltage value. The second target voltage value of the present application is slightly higher than the first target voltage value, which can prevent the high-voltage electrolytic capacitor from being overcharged at the end of the fast charging stage. The stabilizing precision of the digital ignition flame detection circuit 4 is mainly affected by the precision of the second voltage sampling module 42, the conversion precision of the ADC inside the drive control module 1, and the complexity and execution speed of the second algorithm unit 12. In practice, it can reach ±0.5%. In theory, the higher the working frequency of the second algorithm unit 12, the better the stabilizing precision. However, because a low-cost 8-bit MCU can only sample one analog input channel at the same time, and at least two analog channels need to be monitored simultaneously during the stabilizing stage, such as the high-voltage electrolytic capacitor and the flame signal, plus the possibility of interference caused by switching analog channels, it is not appropriate to use the first conversion result after switching channels for algorithm processing. Therefore, the system will first continuously sample the flame signal twice, then continuously sample the second voltage signal twice, and so on, and the system only uses the second sampling of the second voltage signal for stabilizing, so the working frequency of the second algorithm unit is set to 1 / 4 of the first algorithm unit.

[0046] When the voltage of the high-voltage electrolytic capacitor is stabilized to the second target voltage value, the drive control module 1 starts to monitor the heating request from the outside, which can be based on the boiled water signal of the water flow sensor, or the key signal, etc. Here, the Igni signal is used to replace it. When the Igni signal is valid, the drive control module 1 makes the system enter the discharge phase. First, the drive control module 1 stops outputting the PWM1 signal, so that the boost module 2 does not work. Then, the drive control module 1 controls the power supply control module 5 to cut off the power input by outputting the invalid Power signal. Finally, the drive control module 1 controls the trigger discharge module 9 to discharge the CBB capacitor of the ignition module 31 by outputting the Trig signal for a certain time, so as to form an arc discharge. Due to the existence of the primary winding of the high-voltage package, the CBB capacitor will be repeatedly charged and discharged during the discharge process, and its voltage will have a process of oscillating decay until zero volts. After the drive control module 1 stops outputting the Trig signal, the ADC peripheral inside the drive control module 1 will change the input channel again, and change to real-time sampling and conversion of the Volt1 signal output by the first voltage collection module 32. When it is detected that the voltage of the CBB capacitor is continuously lower than a certain value, the drive control module 1 will make the system enter the self-checking phase. When the self-checking is passed, the drive control module 1 will make the system enter the fast charging phase as described above, and then enter the voltage stabilizing phase. When the next ignition cycle comes, for example, 5ms, and the Igni signal is still valid, the system will enter the discharge phase again, and the cycle will continue. Preferably, a trigger voltage of 200V and an ignition frequency of 200Hz can meet the ignition needs of most gas wall-mounted boilers. At the same time, during the discharge period, the power supply control module 5 will cut off the power input, thereby cutting off the charging current. At this time, the greater the capacitance of the high-voltage electrolytic capacitor, the longer the voltage stabilization time will be. Of course, shortening the discharge time is also conducive to the stabilization of the voltage, so after the trigger is completed, the drive control module 1 will enter the self-checking phase as soon as possible according to the Volt1 signal. In addition, unlike the boost module 2 needing to supply power to the ignition module 31 and the high-voltage stabilizing module 41 at the same time during the first fast charging after power-on, when entering the fast charging after voltage stabilization, the boost module 2 only needs to charge the CBB capacitor, and the charging speed will be much faster. The related self-checking criteria need to be adjusted. If the CBB capacitor voltage does not return to the first target voltage value before the next ignition cycle due to various abnormalities, the drive control module 1 will make the system maintain in the fast charging phase, so as to avoid affecting the discharge high voltage, although this will reduce the ignition frequency.

[0047] When the voltage of the high-voltage electrolytic capacitor is stabilized to the second target voltage value, the drive control module 1 also monitors the FSin signal output by the signal rectification module 44, that is, the flame signal. The present application supports a 25M ohm fire detection sensitivity, which is approximately equivalent to the recognition of 4uA level ion current. Of course, the drive control module 1 can output the fire or no fire result to the external unit through the FSout signal. The higher the supply voltage of the high-voltage stabilizing module 41, the higher the resistance value of the pull-up resistor in the signal rectification module 44, and the higher the fire detection sensitivity. However, unnecessarily improving the fire detection sensitivity may not be worth the cost. Moreover, the higher the fire detection sensitivity is not necessarily better. If adaptive is to be done, the fire detection sensitivity needs to be specially configured to make the FSin signal fall into the monitorable area under the commonly used combustion load interval. Preferably, the 25M ohm fire detection sensitivity is to meet the fire detection needs of most gas wall-mounted boiler combustion systems, and to reduce component cost.

[0048] In order to reduce component cost and shorten the time required for self-checking, the working frequency of the alternating square wave module 43 is greatly accelerated to 2kHz, which is controlled by the PWM2 output by the drive control module 1. However, there is a significant delay when the cheap high-voltage triode used by the alternating square wave module 43 is switched from the off state to the on state. Therefore, the duty cycle of the PWM2 signal cannot be 50%, and the present application uses a duty cycle of 47%, that is, the high level time is shortened by 15us compared to the normal value, to compensate for the conduction delay of the high-voltage triode. The benefits of high frequency are that lower-capacity coupling capacitors and rectification filter capacitors can be used, and the periodic self-checking process can be greatly accelerated. The drive control module 1 uses a certain value as a dividing line, such as 2.5V. When the voltage of the FSin signal is higher than this value, the system enters periodic self-checking and the duty cycle of the PWM2 is changed to 100%, which is equivalent to stopping vibration. This can make the coupling capacitor discharge quickly, and then the system will track the FSin signal with a period of 32us. When it is found that the voltage of the FSin signal drops to a certain value, such as 1.25V, the system will restore the duty cycle of the PWM2 to 47%, which is equivalent to restarting vibration. At this time, the FSin signal will also drop and then rise due to inertia, and the system will track the rising curve of the FSin signal to determine whether there is a flame sensing line ground fault. If the FSin signal does not drop during the stop vibration, there is an abnormality in the circuit or the ADC unit of the drive control module 1, and the system will output a no fire result.

[0049] When the voltage of the FSin signal is lower than the boundary line, the system enters the periodic self-checking, and the duty cycle of the PWM2 becomes 0%, which is equivalent to stopping vibration, so that the coupling capacitor can be quickly charged, and then the system tracks the FSin signal. If the FSin signal rises by a certain value, such as 0.3V, within a certain time, the fire detection circuit 4 is normal, and the system restores the duty cycle of the PWM2 to 47%. Otherwise, the circuit or the ADC unit of the drive control module 1 is abnormal, and the system outputs the result of no fire. When the periodic self-checking fails, the drive control module 1 prompts the system, such as displaying on the digital screen or informing the upper system through the communication protocol. Through reasonable timing flow and 2kHz AC square wave frequency, the stopping vibration time of the present application can be shortened to less than 10ms, and the recovery time of the FSin signal is less than 100ms. Although the stopping vibration can cause the FSin signal to rise in a certain time after starting vibration, the program can relax the fire criterion during the oscillation period, so that the periodic self-checking strategy adopted by the present application will not have much impact on the normal fire detection. In contrast, the traditional digital fire detection circuit 4 uses larger capacity values of the coupling capacitor and the rectifier filter capacitor, and in order to effectively distinguish, the required stopping vibration time must be longer, and the power frequency AC square wave frequency will also slow down the recovery time of the flame signal, and the time occupied by the periodic self-checking will be longer.

[0050] In combination with the ignition and fire detection configuration adopted by the present application, the ignition and fire detection integrated circuit has certain adaptability. The manufacturer only needs to adjust the smoke index during production, and does not need to worry about the inability to ignite the fire and detect the fire when delivered to the user's home, thereby reducing a large amount of on-site debugging work. In addition, the integrated scheme saves the DC-DC power supply control chip through the second algorithm unit of the drive control module, improves the performance by increasing the AC square wave frequency, and effectively controls the cost, which is not much higher than the traditional analog fire detection scheme, and is conducive to the promotion of the present application.

[0051] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A digital ignition and flame detection integrated circuit, characterized by comprising: The ignition request input end, the drive control module, the voltage boosting module, the ignition circuit, the trigger discharge module, the fire detection circuit and the flame condition output end are connected respectively. The output end of the drive control module is connected with the input end of the voltage boosting module, the input end of the trigger discharge module and the fire detection circuit respectively; the output end of the trigger discharge module is connected with the input end of the ignition circuit; the output end of the voltage boosting module is connected with the ignition circuit and the fire detection circuit respectively; the drive control module outputs the first pulse signal to the input end of the voltage boosting module; the drive control module outputs the trigger signal according to the ignition request and outputs it to the input end of the ignition circuit through the trigger discharge module; the ignition circuit feeds back the change of the first voltage signal caused by the charging of the voltage boosting module and the discharge of the trigger discharge module to the drive control module; the fire detection circuit feeds back the change of the second voltage signal caused by the charging of the voltage boosting module and the discharge of the load to the drive control module; the drive control module outputs the second pulse signal to the input end of the fire detection circuit; the fire detection circuit feeds back the change of the flame signal voltage caused by the external flame to the drive control module; the drive control module outputs the result of having flame or not having flame from the flame condition output end after logical judgment according to the size of the flame signal voltage, the current system state and the result of the fault self-checking. The fire detection circuit comprises a high-voltage stabilizing module, a second voltage collecting module, an alternating square wave module and a signal rectifying module; the input end of the high-voltage stabilizing module is connected with the output end of the voltage boosting module; the first output end of the high-voltage stabilizing module is connected with the input end of the second voltage collecting module; the output end of the second voltage collecting module is connected with the drive control module, for outputting the second voltage signal collected by the second voltage collecting module to the drive control module; the second output end of the high-voltage stabilizing module is connected with the input end of the alternating square wave module; the input end of the alternating square wave module is connected with the drive control module, for receiving the second pulse signal outputted by the drive control module; the output end of the alternating square wave module is connected with the input end of the signal rectifying module; the output end of the signal rectifying module is connected with the drive control module, for feeding back the flame signal outputted by the signal rectifying module to the drive control module. The drive control module is provided with a first algorithm unit, a second algorithm unit, a ignition signal detection unit, a fault self-checking unit and a flame signal processing unit; the first algorithm unit is used for adjusting the duty cycle of the pulse signal according to the first voltage signal in real time; the second algorithm unit is used for adjusting the duty cycle of the pulse signal according to the second voltage signal in real time; the ignition signal detection unit is used for detecting the ignition signal; the fault self-checking unit is used for realizing the voltage boosting self-checking, the period self-checking and the flame induction line grounding self-checking; the flame signal processing unit is used for processing the flame signal. ​ 2. The digital ignition and flame detection integrated circuit of claim 1, wherein, The working frequency of the second algorithm unit is 1 / 4 of the working frequency of the first algorithm unit.

3. The digital ignition and flame detection integrated circuit of claim 1, wherein, The digital ignition and flame detection integrated circuit further comprises a power supply control module, which is electrically connected with the drive control module and the voltage boosting module respectively, and is used for receiving the drive signal output by the drive control module and supplying power for the voltage boosting module.

4. The digital ignition and flame detection integrated circuit of claim 3, wherein, The digital ignition and flame detection integrated circuit further comprises an overcurrent detection module and an automatic power-off module, the output end of the overcurrent detection module is connected with the input end of the power supply control module, the input end of the automatic power-off module and the input end of the drive control module respectively, the overcurrent detection module is used for outputting a test signal to the drive control module; the automatic power-off module is electrically connected with the power supply control module, and is used for realizing automatic power-off through the test signal output by the overcurrent detection module.

5. The digital ignition and flame detection integrated circuit of claim 4, wherein, The digital ignition and flame detection integrated circuit further comprises a voltage reduction and stabilization module, the input end of the voltage reduction and stabilization module is electrically connected with a power supply, the output end of the voltage reduction and stabilization module is electrically connected with the power supply input end of the drive control module, and the voltage reduction and stabilization module is used for reducing the voltage of the power supply and supplying power for the drive control module.

6. The digital ignition and flame detection integrated circuit of claim 1, wherein, The drive control module is a microcontroller MCU, and the microcontroller is an 8-bit MCU with an 8MHz or 16MHz internal clock.

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