CN113819494A - Low-power-consumption flame ion detection circuit and method with adjustable sensitivity - Google Patents

Abstract

The invention discloses a low-power-consumption flame ion detection circuit with adjustable sensitivity and a method thereof, and the low-power-consumption flame ion detection circuit comprises a CPU (Central processing Unit), a switching tube Q1, a transformer T1, a high-voltage circuit, a switching circuit and an ion current detection circuit, wherein the CPU generates a PWM (pulse-width modulation) signal to the switching tube Q1, the switching tube Q1 is connected with the input end of the transformer T1, one path of the output end of the transformer T1 is connected with a capacitor C1 through a diode D1, one end of the capacitor C1 is connected with the high-voltage circuit, and the other end of the capacitor C1 is connected with the switching circuit; the other output end of the transformer T1 is coupled to a resistor network through a capacitor C2. The flame detection excitation signal is generated without time delay, so that the flame detection time is reduced, the power consumption is reduced, and the service life of a battery is prolonged.

Description

Low-power-consumption flame ion detection circuit and method with adjustable sensitivity

Technical Field

The invention relates to the technical field of cooking utensils, in particular to a low-power-consumption flame ion detection circuit with adjustable sensitivity and a method.

Background

The gas cooker adopts flame ion detection for flameout protection, the gas cooker mostly adopts batteries for power supply, the existing flame ion circuit adopts a transformer for boosting voltage and simultaneously provides an ignition medium voltage and a flame detection excitation signal generation circuit, the voltage of the detection excitation signal is higher, and the voltage of the batteries is two dry batteries, so that the power consumption required by the flame detection excitation signal is larger, generally dozens of milliamperes, and the intermittent detection mode is adopted, although the average current of combustion is reduced, the battery is still larger. Secondly, because the excitation signal is the battery power supply, the voltage of battery reduces along with the live time and leads to excitation signal amplitude diminish to flame detection's sensitivity reduces, leads to easily the false detection under the low battery voltage, easily appears flame-out problem.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a low-power-consumption flame ion detection circuit with adjustable sensitivity and a method thereof.

A low-power-consumption flame ion detection circuit with adjustable sensitivity comprises a CPU (Central processing Unit), a switching tube Q1, a transformer T1, a high-voltage circuit, a switching circuit and an ion current detection circuit, wherein the CPU generates a PWM (pulse-width modulation) signal to the switching tube Q1, the switching tube Q1 is connected with the input end of the transformer T1, one path of the output end of the transformer T1 is connected with a capacitor C1 through a diode D1, one end of the capacitor C1 is connected with the high-voltage circuit, and the other end of the capacitor C1 is connected with the switching circuit; the other output end of the transformer T1 is coupled to a resistor network through a capacitor C2.

Preferably, the CPU, the switching tube Q1, the transformer T1, the diode D1, the capacitor C1, the switching circuit and the high-voltage circuit form a high-voltage ignition circuit, the high-voltage circuit includes a transformer T2 and a switching tube U2, the input end of the transformer T2 is connected to the switching tube U2, and the output end of the transformer T2 is connected to the ignition electrode; the capacitor C1 is boosted, the switch tube U2 is conducted, the capacitor C1 is connected with the input end of the transformer T2, and the output end of the transformer T2 generates high voltage.

Preferably, the switch circuit includes a switch tube U1 and a diode D2, the transformer T1 boosts voltage, a flyback switch boost voltage is generated at an output end of the transformer T2, the switch tube U1 is turned on, and the diode D2 rectifies and charges a capacitor C1.

Preferably, the device further comprises a capacitor C3, wherein one end of the capacitor C3 is connected to the common terminal, and the other end is connected to the resistor network.

Preferably, the ion current detection circuit comprises a capacitor C2, a capacitor C3, a resistor network and a CPU.

Preferably, the resistor network comprises resistors R1, R2 and R3, and the R3 is connected with the flame electrode.

A low-power-consumption flame ion circuit detection method with adjustable sensitivity is applied to an ignition stage and a combustion stage of igniter operation and comprises the following steps:

starting the PWM unit at fixed time, and simultaneously controlling the on-off of a switch tube U1;

judging whether flame is generated;

if no flame is generated, the protection state is entered.

As a preferred mode, when the detection method is applied to the ignition stage, the method specifically comprises the following steps: step 1, starting a PWM unit, starting timing by a timer, and controlling a switching tube U1 to be conducted;

step 2, stopping timing by the timer in the first stage, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, successfully igniting, and entering a combustion stage;

step 3, otherwise, detecting the voltage of the capacitor C1, and controlling the switching tube U2 to ignite;

step 4, if the timing time of the second stage is up, entering step 5, or returning to the first step;

and 5, if the ignition fails again, entering a protection state.

As a preferred mode, when the detection method is applied to a combustion stage, the method specifically includes the following steps: step 1, starting a PWM unit at regular time, and disconnecting a switching tube U1;

step 2, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, judging that flame is generated, and maintaining a combustion state; otherwise, judging that no flame is generated, and entering flameout protection;

and 3, if the combustion is normal, entering a low power consumption mode, and returning to the first step after timing.

Preferably, the pulse width of the PWM is adjusted to a constant excitation signal voltage amplitude as the battery voltage decreases.

Based on the sensitivity-adjustable low-power-consumption flame ion detection circuit and method, a CPU generates a PWM (pulse-width modulation) pulse modulation signal to a control end of a switching tube Q1, a switching signal is generated at a primary end of a transformer T1, the transformer T1 is boosted, a flyback switch is generated at an output end of the transformer T2 and is boosted, a rectifier diode D2 charges a capacitor C1, when a capacitor C1 reaches a preset voltage, the U2 is conducted, the capacitor C1 discharges the primary end of a transformer T2, a secondary end of the transformer T2 generates high voltage, and the high voltage is discharged through an ignition electrode, so that fuel gas is ignited. According to the invention, whether the flame state exists or not is judged by judging the ion current, so that flameout protection is generated.

Drawings

FIG. 1 is a schematic diagram of a flame ion detection circuit according to an embodiment of the invention;

FIG. 2 is a schematic flow chart of the ignition phase of the embodiment of the present invention;

FIG. 3 is a schematic flow diagram of a combustion phase of an embodiment of the present invention;

Detailed Description

The present invention will be described in further detail with reference to the following examples and drawings.

When the flame detection motor is contacted with flame, a weak flame ion current flowing through a grounding loop of the burner is generated, and the signal is amplified and then is converted through a relay output contact to control external equipment. Whether the flame state exists or not is judged through the ion current, and then flameout protection is generated. In this embodiment, the CPU, the switching tube Q1, the transformer T1, the diode D1, the capacitor C1, the switching tube U1, the capacitor C2, the capacitor C3, the resistor R1, the resistor R2, and the resistor R3 constitute an ion current detection circuit, and generate a flame detection excitation signal. Compared with the traditional circuit, the circuit in the embodiment has the advantages that the flame detection excitation signal can be generated without time delay, the flame detection time is shortened, the power consumption is reduced, and the service life of a battery is prolonged.

Referring to fig. 1, the low-power-consumption flame ion detection circuit with adjustable sensitivity comprises a CPU, a switching tube Q1, a transformer T1, a high-voltage circuit, a switching circuit and an ion current detection circuit, wherein the CPU generates a PWM (pulse width modulation) pulse modulation signal to the switching tube Q1, the switching tube Q1 is connected with the input end of the transformer T1, one path of the output end of the transformer T1 is connected with a capacitor C1 through a diode D1, one end of the capacitor C1 is connected with the high-voltage circuit, and the other end of the capacitor C1 is connected with the switching circuit; the other path of the output end of the transformer T1 is coupled to a resistor network through a capacitor C2; the ion current detection circuit comprises a capacitor C2, a capacitor C3, a resistor network and a CPU.

In the first embodiment, referring to fig. 1 to 3, the switching tube Q1, the transformer T1, and the rectifier diode D1 form a flyback switching boost circuit, the switching tube Q1 is turned on, and power flows through the primary side of the transformer T1 to excite the transformer T1; the switching tube Q1 is disconnected, the transformer T1 generates counter electromotive force, and the energy storage C1 is charged through the rectifier diode D1; the switching tube Q1 may be a triode switching tube or a MOS switching tube, and is preferably a MOS tube in this embodiment;

when C1 is close to 100V, detecting the voltage of a capacitor C3 to judge whether ignition occurs or not; if no ignition occurs, the capacitor C1 is continuously charged, when the capacitor C1 reaches 150V, whether the ignition voltage is reached is judged, the ignition voltage is detected through a secondary tap, after the ignition voltage is reached, the PWM pulse modulation signal output is stopped, the switching tube U2 is controlled to be connected, at the moment, the switching tube U1 is automatically turned off due to no current, the diode D2 is connected, the C1 is subjected to primary discharge through the high-voltage transformer T2, air spark discharge is generated at an ignition electrode, and gas is ignited. The switching tube U1 and the switching tube U2 are preferably thyristor switching tubes.

In a second embodiment, referring to fig. 1 to 3, after ignition, a timer sets a timing time, a PWM unit is started at a timing, and the PWM unit sets a pulse width according to the battery voltage to maintain the constant of the excitation voltage, wherein the pulse width of the PWM excitation is smaller than the pulse width at the time of ignition;

the switch tube U1 and the switch tube U2 are closed, and the capacitor C1 is forbidden to be charged. When the energy storage capacitor C1 is charged, the excitation signal is slowly increased in amplitude during the charging process, energy is stored in the capacitor C1, the capacitor C1 leaks during the non-detection process, the power consumption is increased, and the switch tube U1 is closed to enable the excitation signal to reach a preset value immediately.

When the battery voltage is reduced, the amplitude of the excitation signal voltage can be constant by adjusting the PWM pulse width, and the flame detection sensitivity under low battery voltage is ensured.

Referring to fig. 1, the CPU, the switching tube Q1, the transformer T1, the diode D1, the capacitor C1, the switching circuit and the high-voltage circuit form a high-voltage ignition circuit, the high-voltage circuit includes a transformer T2 and a switching tube U2, the input end of the transformer T2 is connected to the switching tube U2, and the output end is connected to the ignition electrode; the capacitor C1 is boosted, the switch tube U2 is conducted, the capacitor C1 is connected with the input end of the transformer T2, and the output end of the transformer T2 generates high voltage; the switching circuit comprises a switching tube U1 and a diode D2, the transformer T1 boosts voltage, a flyback switch is generated at the output end of the transformer T2 to boost voltage, the switching tube U1 is conducted, and the diode D2 charges a capacitor C1 after rectification.

The CPU generates a PWM (pulse-width modulation) signal to a switching tube Q1, generates a switching signal at the primary side of a transformer T1, boosts the voltage through a transformer T1, generates a flyback switching boost at the output end of the transformer T2, rectifies the voltage through a diode D2 and charges C1, and at the moment, U1 is conducted. When the C1 reaches a preset voltage, the U2 is conducted, the C1 discharges to the primary side of the T2, a high voltage of over ten thousand volts is generated on the secondary side of the transformer T2, and the high voltage is discharged through the ignition electrode, so that the fuel gas is ignited.

The capacitor C3 is also included, one end of the capacitor C3 is connected with the common terminal, and the other end is connected with the resistance network. The voltage of the capacitor C3 is proportional to the ion current, and the larger the ion current, the lower the negative voltage of C3. And the higher the amplitude of the excitation signal, the higher the ion current, and the more sensitive the induction circuit.

The resistor network comprises resistors R1, R2 and R3, and the R3 is connected with the flame electrode. The resistor R3 is connected with the flame detection electrode, and comprises three conditions, namely, no flame, and an open circuit is formed between the detection electrode and the ground. No current flows through R3, the voltage at C3 is the charging voltage of R1 and R2, and the voltage at C3 is 0 because the positive and negative energies are equal.

And secondly, a flame exists, and the unidirectional property between the flame electrode and the ground due to the ion current is equivalent to a diode. I.e. the positive half cycle of the excitation signal is shunted through R3 and the negative half cycle is open circuit or low current. Thus the positive and negative charge at C3 results in a negative voltage.

And thirdly, short circuit or leakage exists between the flame electrode and the ground, when the short circuit or the leakage is large, the shunt is large, and the voltage negative pressure on the capacitor C3 is small.

The capacitor C2 is coupled, so that charging and discharging currents are generated on the resistors R1, R2, R3 and the capacitor C3, and when flame occurs, negative pressure is generated on the capacitor C3; the negative pressure can be used as the input of a comparator through a bias circuit, and whether the negative pressure of the amplifying capacitor C3 is lower than a threshold value is judged from the output of the comparator, so that whether flame is generated is judged; or the voltage of the capacitor C3 is amplified by an amplifier, and the A/D acquisition judgment is carried out.

A sensitivity-adjustable low-power consumption flame ionization circuit detection method, referring to fig. 2 and 3, the detection method is applied to an ignition phase and a combustion phase of an igniter operation, and comprises the following steps:

starting the PWM unit at fixed time, and simultaneously controlling the on-off of a switch tube U1; the circuit controls the on-off of the switch tube U1, when a flame detection excitation signal is generated, the voltage of the transformer T1 does not have a charging loop on the energy storage capacitor C1, and the flame excitation signal can reach a preset amplitude without time delay.

Judging whether flame is generated or not, wherein the flame at the moment comprises flame during ignition and a flame state after combustion; if no flame is generated, the protection state is entered.

In an embodiment, when the detection method is applied to the ignition stage, the circuit principle is as described in the first embodiment, and specifically includes the following steps: step 1, starting a PWM unit, starting timing by a timer, and controlling a switching tube U1 to be conducted; when the U1 switch is controlled to be conducted and a flame detection excitation signal is generated, the voltage of the transformer T1 does not have a charging loop on the capacitor C1, and the flame excitation signal can reach a preset amplitude without time delay.

Step 2, stopping timing by the timer in the first stage, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, successfully igniting, and entering a combustion stage; the CPU controls PWM generation, whether flame is generated or not is detected in a time window, namely timing in the first stage, so that the interference of ignition spark discharge on flame detection is avoided, and the reliability of ignition detection is improved.

Step 3, otherwise, detecting the voltage of the capacitor C1, and controlling the switching tube U2 to ignite; at this time, the switching tube U1 is automatically turned off due to no current, the diode D2 is turned on, the capacitor C1 primarily discharges through the high voltage transformer T2, and air spark discharge is generated at the ignition electrode to ignite the gas.

Step 4, if the timing time of the second stage is up, entering step 5, or returning to the first step; and if the step 3 fails to be executed, entering a step 5 to finish flameout protection, or returning to the first step for re-ignition.

And 5, if the ignition fails again, entering a protection state.

In another embodiment, when the detection method is applied to the combustion stage, the circuit principle is as described in the second embodiment above, with reference to fig. 3, and specifically includes the following steps: step 1, starting a PWM unit at regular time, and disconnecting a switching tube U1; the transformer T1 generates boosting, the working current is large, the power consumption is large when the working time is long, the signal generation time is greatly shortened due to the U1, the power consumption is reduced, and the excitation signal reaches a preset value immediately after the switch tube U1 is closed.

Step 2, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, judging that flame is generated, and maintaining a combustion state; otherwise, judging that no flame is generated, and entering flameout protection; the output of the capacitor C3 and the comparator is detected, the comparator circuit can set a threshold value to prevent the comparator from turning over under the conditions of no flame and electric leakage, the comparator turns over under the condition of flame, and whether flame is generated or not is judged according to the output of the comparator. When negative pressure is generated on the capacitor C3 when flame exists, the negative pressure can pass through the bias circuit and is used as the input of the comparator, whether the negative pressure of the capacitor C3 is lower than a threshold value is judged from the output of the comparator, so that whether the flame is generated or not is judged, the voltage of the capacitor C3 can be amplified through the amplifier, and the judgment is carried out through A/D collection.

And 3, if the combustion is normal, entering a low power consumption mode, and returning to the first step after timing. The flame detection excitation signal is generated without time delay, so that the flame detection time is shortened, and the power consumption is reduced.

And when the voltage of the battery is reduced, adjusting the pulse width of the PWM to be the voltage amplitude of the constant excitation signal. The PWM pulse width is obtained by calculating the voltage of the battery so as to generate an excitation signal with constant amplitude, and when the voltage of the battery is reduced, the voltage amplitude of the excitation signal can be constant by adjusting the PWM pulse width, so that the flame detection sensitivity under low battery voltage is ensured. In this embodiment, the operating current of the igniter is set to 5-10mA, and the average current of the excitation signal is reduced by 1.5 mA.

The invention has been described in terms of a sensitivity-adjustable low-power flame ion detection circuit and method for facilitating understanding of the invention, but the embodiments of the invention are not limited to the above-described embodiments, and any changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit of the invention are intended to be equivalent substitutions and are intended to be included within the scope of the invention.

Claims (10)

1. A low-power-consumption flame ion detection circuit with adjustable sensitivity is characterized by comprising a CPU, a switching tube Q1, a transformer T1, a high-voltage circuit, a switching circuit and an ion current detection circuit, wherein the CPU generates a PWM (pulse-width modulation) pulse modulation signal to the switching tube Q1, the switching tube Q1 is connected with the input end of the transformer T1, one path of the output end of the transformer T1 is connected with a capacitor C1 through a diode D1, one end of the capacitor C1 is connected with the high-voltage circuit, and the other end of the capacitor C1 is connected with the switching circuit; the other output end of the transformer T1 is coupled to a resistor network through a capacitor C2.

2. The adjustable sensitivity low-power consumption flame ion detection circuit as claimed in claim 1, wherein the CPU, the switching tube Q1, the transformer T1, the diode D1, the capacitor C1, the switching circuit and the high-voltage circuit form a high-voltage ignition circuit, the high-voltage circuit comprises a transformer T2 and a switching tube U2, the input end of the transformer T2 is connected with the switching tube U2, and the output end of the transformer T2 is connected with an ignition electrode; the capacitor C1 is boosted, the switch tube U2 is conducted, the capacitor C1 is connected with the input end of the transformer T2, and the output end of the transformer T2 generates high voltage.

3. The adjustable sensitivity low-power consumption flame ion detection circuit as claimed in claim 1, wherein the switching circuit comprises a switching tube U1 and a diode D2, a transformer T1 boosts voltage, a flyback switching boost voltage is generated at an output end of the transformer T2, the switching tube U1 is turned on, and the diode D2 charges a capacitor C1 after rectification.

4. The adjustable sensitivity low power consumption flame ion detection circuit of claim 1, further comprising a capacitor C3, wherein one end of the capacitor C3 is connected to the common terminal, and the other end is connected to the resistor network.

5. The adjustable sensitivity low power consumption flame ion detection circuit of claim 1, wherein the ion current detection circuit comprises a capacitor C2, a capacitor C3, a resistor network and a CPU.

6. The adjustable sensitivity low power consumption flame ion detection circuit as claimed in any one of claims 1 to 5, wherein the resistor network comprises resistors R1, R2 and R3, and the R3 is connected with the flame electrode.

7. A low-power-consumption flame ion circuit detection method with adjustable sensitivity is applied to an ignition stage and a combustion stage of igniter operation, and is characterized by comprising the following steps:

starting the PWM unit at fixed time, and simultaneously controlling the on-off of a switch tube U1;

judging whether flame is generated;

if no flame is generated, the protection state is entered.

8. The adjustable sensitivity low power consumption flame ionization circuit detection method according to claim 7, wherein when the detection method is applied to an ignition stage, the detection method specifically comprises the following steps: step 1, starting a PWM unit, starting timing by a timer, and controlling a switching tube U1 to be conducted;

step 2, stopping timing by the timer in the first stage, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, successfully igniting, and entering a combustion stage;

step 3, otherwise, detecting the voltage of the capacitor C1, and controlling the switching tube U2 to ignite;

step 4, if the timing time of the second stage is up, entering step 5, or returning to the first step;

and 5, if the ignition fails again, entering a protection state.

9. The adjustable sensitivity low power consumption flame ionization circuit detection method according to claim 7, wherein when the detection method is applied to a combustion stage, the detection method specifically comprises the following steps: step 1, starting a PWM unit at regular time, and disconnecting a switching tube U1;

step 2, judging whether the voltage of the capacitor C3 is lower than a threshold value, if so, judging that flame is generated, and maintaining a combustion state; otherwise, judging that no flame is generated, and entering flameout protection;

and 3, if the combustion is normal, entering a low power consumption mode, and returning to the first step after timing.

10. The adjustable sensitivity low power consumption flame ionization circuit detection method of claim 7, wherein when the battery voltage decreases, the pulse width of the PWM is adjusted to a constant excitation signal voltage amplitude.

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