System and method for temperature control of a hot surface igniter based on thermal resistance measurements

Abstract

A temperature control system and method for a hot surface igniter based on thermal resistance measurement includes a power supply module configured to supply power to the hot surface igniter, a control module configured to control the output voltage of the power supply module, a measurement module configured to measure the resistance of the hot surface igniter, a storage module pre-stored with a resistance-temperature table and a set temperature value, a calculation module configured to find a corresponding actual temperature value from the resistance-temperature table pre-stored in the storage module based on the resistance value, and a comparison module configured to compare the actual temperature value with the set temperature value to obtain a temperature difference value. The calculation module is further configured to obtain a voltage control amount based on the temperature difference value, and the control module controls the supplied power output of the power supply module based on the voltage control amount until the calculated actual temperature value matches the set temperature value, thereby achieving more accurate temperature regulation.

Description

[Technical Field]

[0001] The present invention relates to temperature control technology, and more particularly to a system and method for temperature control of a hot surface ignition device based on thermal resistance measurements. [Background technology]

[0002] Electric sparks generated during the high frequency ignition process can easily cause dangerous combustion or explosion conditions. The hot surface ignition technology used by hot surface ignition devices can completely avoid potential problems caused by electric sparks by allowing the flammable gas / fuel to enter the combustion area after the hot surface ignition device has reached a high temperature in advance. Therefore, hot surface ignition devices are gradually replacing traditional high frequency ignition devices.

[0003] Currently, the temperature that a hot surface igniter can reach during use is related to the magnitude of the voltage applied across the hot surface igniter. Therefore, to make the hot surface igniter reach the temperature required by the user, the supply voltage of the hot surface igniter's power must be adjusted. However, in practice, on the one hand, the supply voltage of the hot surface igniter is usually increased to quickly make the hot surface igniter reach the required temperature. On the other hand, to minimize damage to the hot surface igniter, the supply voltage must be reduced and adjusted in a timely manner once the required temperature is reached. On the other hand, because the hot surface igniter needs to reach different temperatures under the operating conditions of different applications, the supply voltage must be adjusted according to the temperature.

[0004] Chinese Patent CN 1640195 B discloses a system and method for regulating the voltage of a resistance igniter. The system and method determine the line voltage of a system and control the voltage applied to the resistance igniter. An initially applied first voltage is maintained for a fixed period of time, after which a second voltage, which is the rated voltage of the igniter, is applied. The system and method determine the line voltage of the system and control the voltage applied to the resistance igniter. An initially applied first voltage is maintained for a fixed period of time, after which a second voltage, which is the rated voltage of the igniter, is applied. The system and method shortens the time required to heat the resistance igniter to a temperature sufficient to ignite the gas and regulates the output voltage supplied to the igniter to prevent damage to the igniter due to overvoltage. The system and method shortens the time required to heat the resistance igniter to a temperature sufficient to ignite the gas and regulates the output voltage supplied to the igniter to prevent damage to the igniter due to overvoltage.

[0005] Although the above invention measures the output voltage, the actual voltage supplied to the hot surface igniter throughout the circuit is not exactly equal to the output voltage, and therefore using the output voltage to characterize the voltage of the hot surface igniter is inaccurate, resulting in an inaccurate voltage being supplied to the hot surface igniter, which in turn results in inaccurate temperature control of the hot surface igniter. Summary of the Invention [Problem to be solved by the invention]

[0006] To solve the problem of inaccurate temperature control of a hot surface igniter in the prior art, the present disclosure provides a temperature control system for a hot surface igniter based on thermal resistance measurement, the system includes: a power supply module configured to supply power to the hot surface igniter; a control module configured to control the output voltage of the power supply module; a measurement module configured to measure and obtain a resistance value of the hot surface igniter; a storage module having a resistance-temperature table and a set temperature value pre-stored therein; a calculation module configured to find a corresponding actual temperature value from the electronic temperature table pre-stored in the storage module based on the resistance value; and a comparison module configured to compare the actual temperature value with the set temperature value to obtain a temperature difference value, wherein the calculation module is further configured to obtain a voltage control amount based on the temperature difference value, and the control module is configured to control the power supply output of the power supply module according to the voltage control amount until the calculated actual temperature value matches the set temperature value. [Means for solving the problem]

[0007] In this solution, the resistance value of the hot surface igniter is measured using a measurement module, and then the calculation module looks up the temperature value in a set resistance value-temperature table. Compared with the prior art, the resistance value obtained in this solution is closer to the resistance value of the hot surface igniter itself, so the obtained temperature value is more accurate. The calculation module obtains the temperature difference between the temperature value and the set temperature value, and then obtains a voltage control variable. Finally, the control module adjusts the power supply output according to the voltage control variable, thereby achieving more accurate temperature control.

[0008] Preferably, the measurement module is configured to measure a terminal voltage and a current of the hot surface igniter, and the calculation module is configured to obtain a resistance value of the hot surface igniter based on the terminal voltage and the current.

[0009] Preferably, the measurement module integrates a current measurement circuit for acquiring a current value of the hot surface ignition device and a terminal voltage measurement circuit for acquiring a voltage value of the hot surface ignition device.

[0010] Preferably, the current measurement circuit includes a first sampling resistor connected to the positive voltage terminal of the power supply module and one electrode of the hot surface igniter, and a first amplifier circuit for amplifying the voltage of the first sampling resistor, with the other electrode of the hot surface igniter electrically connected to the negative voltage terminal of the power supply module. In this solution, when power is supplied to the hot surface igniter, current flows through the positive voltage terminal of the power supply, the first sampling resistor, the one electrode of the hot surface igniter, the hot surface igniter, and the other electrode of the hot surface igniter, and finally returns to the negative voltage terminal of the power supply. The current flowing through the hot surface igniter is converted to a small voltage by the first sampling resistor. After being amplified by the first amplifier circuit, a voltage Vrt is output, which is linearly related to the current flowing through the hot surface igniter. Finally, a processing module calculates the current value of the hot surface igniter based on the proportional relationship between the voltage Vrt and the current of the hot surface igniter. This solution has a simple structure.

[0011] Preferably, the terminal voltage measurement circuit includes a positive voltage terminal of the power supply, a second sampling resistor, a third sampling resistor, and a negative voltage terminal of the power supply, connected in series, and further includes a second amplifier circuit for amplifying the terminal voltage of the third sampling resistor, the second sampling resistor and the third sampling resistor being connected in series with each other and in parallel to the hot surface igniter. In this solution, the second sampling resistor and the third sampling resistor are connected in series, and the hot surface igniter is connected in parallel to the second and third sampling resistors connected in series. Therefore, after obtaining the terminal voltage of the third sampling resistor using the second amplifier circuit, the current voltage value of the hot surface igniter can be calculated based on the proportional relationship between the terminal voltage of the third sampling resistor and the terminal voltage of the hot surface igniter. This has a simple structure.

[0012] Preferably, the calculation module uses PID calculation to calculate the temperature difference value and obtain the voltage control amount, and this solution uses PID calculation to obtain the voltage control amount, which can effectively correct the temperature deviation and make the temperature reach a stable state.

[0013] In a second aspect, the present disclosure provides a temperature control method using the temperature control system for a hot surface ignition device based on thermal resistance measurement described above, the method comprising: a power supply step of supplying power to the hot surface igniter; a control step for controlling the output voltage; a measuring step of measuring a resistance value of the hot surface igniter; a calculating step of finding a corresponding actual temperature value from a pre-stored electronic temperature table according to the resistance value; and a feedback step of comparing the actual temperature value with a set temperature value to obtain a temperature difference value, obtaining a voltage control amount according to the temperature difference value, and feeding back the voltage control amount to the control step; In the control step, the output voltage is controlled in accordance with the voltage control amount fed back until the calculated actual temperature value coincides with the set temperature value. [Effects of the Invention]

[0014] The present disclosure has the following advantageous effects. 1. Compared with the prior art, the present disclosure obtains the current temperature of the thermal surface ignition device by measuring the voltage value and current value of the thermal surface ignition device, and calculates the voltage control amount based on the temperature difference between the current temperature and the set temperature value, and feeds it back to the control module, thereby realizing voltage control of the thermal surface ignition device and making the temperature control more accurate. [Brief explanation of the drawings]

[0015] FIG. 1 is a modular block diagram of one embodiment of the thermal resistance measurement based hot surface ignition temperature control system and method of the present disclosure.

[0016] FIG. 2 is a circuit diagram of an H-bridge drive circuit.

[0017] FIG. 3 is a diagram of the current measurement circuit.

[0018] FIG. 4 is a diagram of the terminal voltage measurement circuit. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in further detail below in conjunction with specific embodiments.

[0020] 1.Definition PID algorithm: It is a very classic control algorithm and is widely used in the industrial control field as a typical closed-loop control algorithm (i.e., negative feedback control). The PID algorithm consists of P (proportional control), I (integral control), and D (derivative control).

[0021] 2. An embodiment is substantially as shown in FIG. 1. The temperature control system for a hot surface igniter based on thermal resistance measurement includes a power supply module configured to supply power to the hot surface igniter, a control module configured to control the output voltage of the power supply module, and a measurement module configured to measure the resistance value of the hot surface igniter. In particular, the resistance value measurement in this embodiment is obtained by measuring the terminal voltage and current of the hot surface igniter. The measurement module integrates a current measurement circuit for acquiring the current value of the hot surface igniter and a terminal voltage measurement circuit for acquiring the voltage value of the hot surface igniter. In particular, the current measurement circuit includes a first sampling resistor connected to the positive voltage terminal of the power supply module and one electrode of the hot surface igniter, and a first amplifier circuit for amplifying the voltage of the first sampling resistor, and the other electrode of the hot surface igniter is electrically connected to the negative voltage terminal of the power supply module. The terminal voltage measurement circuit includes a positive voltage terminal of the power supply, a second sampling resistor, a third sampling resistor, and a negative voltage terminal of the power supply, which are connected in series in this order, and further includes a second amplifier circuit for amplifying the terminal voltage of the third sampling resistor, where the second sampling resistor and the third sampling resistor are connected in series with each other and are further connected in parallel to the hot surface ignition device.

[0022] The system includes a storage module having a resistance-temperature table and a set temperature value preset therein, a calculation module configured to obtain a resistance value of the hot surface ignition device based on a terminal voltage and a current, and after obtaining the resistance value, find a corresponding actual temperature value from an electronic temperature table pre-stored in the storage module, and a comparison module configured to compare the actual temperature value with the set temperature value to obtain a temperature difference value, the calculation module is further configured to calculate the temperature difference value using a PID algorithm to obtain a voltage control variable, and the control module is configured to control the power supply output of the power supply module according to the voltage control variable until the calculated actual temperature value matches the set temperature value.

[0023] This embodiment further discloses a temperature control method for a temperature control system of a hot surface ignition device based on thermal resistance measurement, the method comprising: a power supply step of supplying power to the hot surface igniter; a control step for controlling the output voltage; a measuring step of measuring the resistance of the hot surface igniter, in particular the terminal voltage and current of the hot surface igniter; A calculation step of obtaining a resistance value of the hot surface ignition device based on the terminal voltage and the current, and after obtaining the resistance value, finding a corresponding actual temperature value from a pre-stored electronic temperature table; and a feedback step of comparing the actual temperature value with a set temperature value to obtain a temperature difference value, obtaining a voltage control amount according to the temperature difference value, and feeding back the voltage control amount to a control step; In the control step, the output voltage is controlled based on the voltage control amount fed back until the calculated actual temperature value matches the set temperature value.

[0024] The specific implementation procedure is as follows: In this embodiment, the power supply module supplies power to the hot surface igniter based on a PWM pulse square wave voltage. When power is supplied, the H-bridge driver circuit is driven to reverse the current flowing through the hot surface igniter, as shown in Figure 2. Here, CN1 and CN2 of the H-bridge driver circuit are the connection points of the two electrodes of the hot surface igniter, and the driver circuit includes four MOSFETs Q1, Q4, Q2, and Q3, which are turned on and off in a predetermined sequence to achieve the reversal of the current flowing through the hot surface igniter.

[0025] As shown in Figure 3, when measuring the current of the hot surface igniter, IGT is the hot surface igniter, R1 is the first sampling resistor, OPA is the first amplifier circuit, and V+ and V- are the positive and negative voltage terminals of the power supply to the hot surface igniter, respectively. When power is supplied to the hot surface igniter IGT, the current I flows through V+, R1, CN1, the hot surface igniter IGT, CN2, and finally back to V-. The current I through the hot surface igniter IGT is converted to a small voltage by the first sampling resistor R1. After being amplified by the first amplifier circuit OPA, a voltage Vrt is output, which is linearly related to the current I through the hot surface igniter. This voltage Vrt is sent to a processing module. The processing module calculates the current value of the hot surface igniter IGT based on the proportional relationship between the voltage Vrt and the current through the hot surface igniter IGT.

[0026] The terminal voltage measurement circuit shown in Figure 4 obtains a voltage value Vp representing the magnitude of the terminal voltage when measuring the voltage of the hot surface igniter, and transmits the voltage value Vp to the processing module. The processing module calculates the current terminal voltage of the hot surface igniter based on the proportional relationship between the voltage value Vp and the terminal voltage of the hot surface igniter IGT. Finally, the processing module calculates the current resistance value (i.e., thermal resistance) Rt of the hot surface igniter based on the measured voltage and current of the hot surface igniter. Then, based on the obtained resistance value, the processing module looks up the temperature value corresponding to the resistance value in a preset resistance-temperature table.

[0027] After obtaining the actual temperature value, the comparison module first obtains the temperature difference between the actual temperature value and the set temperature value. The obtained temperature difference value is subjected to PID calculation by the calculation module to obtain a voltage control amount that is fed back to the control module. The control module adjusts the output voltage according to the voltage control amount. Next, the measurement module measures a new current value and a new voltage value. The calculation is repeated. Finally, the temperature of the hot surface ignition device is controlled to the set temperature value.

[0028] The specific process for adjusting the output voltage in the above process uses the control technology described in the patent applications filed by our company. In particular, in an example based on a PWM pulse square wave voltage, when the rising edge of the PWM voltage acting on the hot surface igniter arrives, the measurement module measures the voltage and current of the hot surface igniter. After calculating a voltage control amount, the control module adjusts the voltage control amount accordingly. During the adjustment, the ratio of the Ton period and the Toff period of the PWM pulse square wave voltage is adjusted according to the voltage control amount, thereby ensuring that the appropriate voltage is supplied to the hot surface igniter and that the hot surface igniter operates at the set temperature.

[0029] In another embodiment, the power supply module may supply power in a steady-state DC power supply mode. In this power supply mode, the temperature of the hot surface igniter is regulated by adjusting the power supply time. Specifically, the power supply module applies voltage to the hot surface igniter for a certain period of time, and then stops supplying power. At this time, the measurement module measures the current and voltage of the hot surface igniter, and the control module controls the power supply time of the power supply module according to the voltage control variable. In this mode, the voltage supplied to the hot surface igniter is periodically turned off for a very short period of time, for example, 0.1 ms, during which the voltage control variable is measured and calculated. Thereafter, the power supply module immediately starts supplying power again. Because the hot surface igniter has a certain thermal inertia, this very short off time does not affect the temperature continuity of the hot surface igniter. Therefore, normal temperature rise of the hot surface igniter can be ensured.

[0030] The above content is merely an embodiment of the present disclosure, and common general knowledge, such as well-known specific structures and characteristics of the solutions of the present invention, is not redundantly described in this specification. Those skilled in the art are aware of all common general knowledge in the technical field to which the present invention pertains prior to the filing date or priority date, have access to all prior art in the field, and are capable of applying routine experimental means prior to the said date. Those skilled in the art can improve and implement the solutions of the present invention based on the motivation set forth in this application and in combination with their own abilities. Some typical well-known structures or methods should not pose an obstacle to those skilled in the art in carrying out the present application. Those skilled in the art may make various modifications and improvements without departing from the scope of the present application, and these modifications and improvements are also considered to fall within the scope of protection of the present invention. None of these modifications and improvements affect the practical effects and patent applicability of the present invention. The scope of protection of the present application is limited by the claims, and the disclosure of specific embodiments, etc. in the specification can be used to interpret the claims.

Claims

1. 1. A temperature control system for a hot surface ignition device based on thermal resistance measurements, comprising: a power supply module configured to supply power to the hot surface igniter; a control module configured to control the output voltage of the power supply module; a measurement module configured to measure and obtain a resistance value of the hot surface igniter; a storage module in which a resistance-temperature table and a set temperature value are preset; a calculation module configured to find a corresponding actual temperature value from an electronic temperature table pre-stored in the memory module based on the resistance value; a comparison module configured to compare the actual temperature value with the set temperature value to obtain a temperature difference value; the calculation module is further configured to obtain a voltage control amount based on the temperature difference value, and the control module is configured to control the power supply output of the power supply module based on the voltage control amount until the calculated actual temperature value matches the set temperature value. Temperature control system for hot surface ignition devices based on thermal resistance measurements.

2. 2. The temperature control system of a hot surface igniter based on thermal resistance measurement of claim 1, wherein the measurement module is configured to measure a terminal voltage and a current of the hot surface igniter, and the calculation module is configured to obtain a resistance value of the hot surface igniter based on the terminal voltage and the current.

3. 3. The temperature control system for a hot surface ignition device based on thermal resistance measurement as described in claim 2, wherein the measurement module is integrated with a current measurement circuit for acquiring a current value of the hot surface ignition device and a terminal voltage measurement circuit for acquiring a voltage value of the hot surface ignition device.

4. 4. The temperature control system for a hot surface igniter based on thermal resistance measurement according to claim 3, wherein the current measurement circuit includes a first sampling resistor connected to the positive voltage terminal of the power supply module and one electrode of the hot surface igniter, and a first amplifier circuit for amplifying the voltage of the first sampling resistor, and the other electrode of the hot surface igniter is electrically connected to the negative voltage terminal of the power supply module.

5. 5. The temperature control system for a hot surface ignition device based on thermal resistance measurement according to claim 3 or 4, wherein the terminal voltage measurement circuit is configured such that the positive voltage terminal of the power supply, a second sampling resistor, a third sampling resistor, and the negative voltage terminal of the power supply are connected in series in this order, and further includes a second amplifier circuit for amplifying the terminal voltage of the third sampling resistor, wherein the second sampling resistor and the third sampling resistor are connected in series with each other and are further connected in parallel with the hot surface ignition device.

6. The temperature control system for a hot surface ignition device based on thermal resistance measurement according to claim 5 , wherein the calculation module calculates the temperature difference value using a PID calculation to obtain the voltage control amount.

7. A temperature control method using the temperature control system for a hot surface ignition device based on thermal resistance measurement according to any one of claims 1 to 6, comprising: a power supply step of supplying power to the hot surface igniter; a control step for controlling the output voltage; a measuring step of measuring a resistance value of the hot surface igniter; a calculating step of finding a corresponding actual temperature value from a pre-stored electronic temperature table according to the resistance value; and a feedback for comparing the actual temperature value with a set temperature value to obtain a temperature difference value, obtaining a voltage control amount according to the temperature difference value, and feeding back the voltage control amount to the control step; In the control step, the output voltage is controlled in accordance with the voltage control amount fed back until the calculated actual temperature value matches the set temperature value.

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