Zirconia-based high temperature sensor control compensation circuit and method

Abstract

The application discloses a zirconia-based high-temperature sensor control compensation circuit and method, and belongs to the field of automobile electronic sensing and detection. The circuit comprises an internal resistance measuring unit, a microcontroller and a heating driving unit. The internal resistance measuring unit and the microcontroller work cooperatively to measure and calculate the internal resistance of the zirconia-based high-temperature sensor. The microcontroller adjusts a target temperature value according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and performs fuzzy PID control according to the deviation value of the internal resistance relative to a reference resistance, so as to output a heating control signal. The heating driving unit drives a sensor heater according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value. The compensation correction of the influence of the sensor internal resistance attenuation temperature control is realized, and the temperature control precision and the detection precision of the sensor are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of automobile electronic sensing detection, and more particularly relates to a zirconia-based high-temperature sensor control compensation circuit and method. BACKGROUND

[0002] Automobile exhaust and industrial flue gas mainly contain harmful gases and substances such as NOx, SO2 and PM2.5, and have the characteristics of complex atmosphere composition and large temperature fluctuation range. Conventional electrochemical and electronic atmosphere concentration sensors are not suitable for this application environment. Zirconia-based high-temperature gas sensors use zirconia as a solid electrolyte and have high temperature resistance, and can be widely used in automobile exhaust detection, industrial flue gas detection, carbon emission detection and many other fields. In these application environments, the efficiency, performance and reliability of the system depend on the accuracy and durability of the zirconia-based high-temperature sensor. In the application process of the zirconia-based high-temperature gas sensor, the temperature and the zirconia solid electrolyte unit are mainly controlled. The difficulty of temperature control lies in the measurement of temperature, and on the other hand, the accuracy of temperature control affects the measurement performance of the sensor.

[0003] The existing temperature control method of the zirconia-based high-temperature gas sensor mainly focuses on dew point protection and heating drive. Usually, the temperature measurement is realized based on the temperature resistance characteristics of the platinum heater, for example, the temperature measurement is realized based on the temperature resistance characteristics of the three-wire platinum heating wire. The temperature control method and accuracy of the three-wire heater are different from those of the two-wire heater, and at the same time, the platinum heater will also produce aging attenuation after long-term work, and the temperature resistance coefficient will drift. In addition, the temperature control based on the temperature resistance characteristics of the heater cannot accurately reflect the actual working temperature of the solid electrolyte unit. Although Bosch has developed a special chip for five-wire wide-range oxygen sensors, which integrates an internal resistance measurement function, but it is based on the direct current pulse method, and the special chip is not universal. Therefore, how to reduce the influence of the internal resistance attenuation of the zirconia-based solid electrolyte unit on the temperature control and measurement performance of the sensor has important research significance. SUMMARY

[0004] In view of the defects and improvement needs of the prior art, the present application provides a zirconia-based high-temperature sensor control compensation circuit and method, which aims to compensate and correct the influence of the internal resistance attenuation of the zirconia-based solid electrolyte unit on the temperature control and measurement performance of the sensor.

[0005] To achieve the above object, according to one aspect of the present application, a zirconia-based high-temperature sensor control compensation circuit is provided, characterized in that it comprises: an internal resistance measuring unit, a microcontroller and a heating driving unit; the internal resistance measuring unit and the microcontroller work together to measure and calculate the internal resistance of the zirconia-based high-temperature sensor; the microcontroller adjusts the target temperature value according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and performs fuzzy PID control according to the deviation value of the internal resistance relative to the reference resistance, thereby outputting a heating control signal; the heating driving unit drives the sensor heater according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value.

[0006] Further, the microcontroller is further configured to calculate the internal resistance decay coefficient of the zirconia-based high-temperature sensor, and compensate the induced voltage measured by the zirconia-based high-temperature sensor according to the internal resistance decay coefficient.

[0007] Further, the microcontroller controls the sensor heater to work at a first power, measures a first internal resistance of the zirconia-based high-temperature sensor at a first temperature; after a set time, the microcontroller controls the sensor heater to work at the first power, measures a second internal resistance of the zirconia-based high-temperature sensor at the first temperature; the internal resistance decay coefficient is equal to the ratio of the second internal resistance to the first internal resistance.

[0008] Further, the microcontroller stores a corresponding relationship between the internal resistance decay coefficient and the induced voltage compensation amount.

[0009] Further, the internal resistance measuring unit comprises: an alternating current signal generating circuit, an internal resistance measuring reference circuit and a high-pass filter circuit; the alternating current signal generating circuit applies an alternating current voltage signal u to the zirconia-based high-temperature sensor, obtains an internal resistance measuring signal, and outputs the signal to the microcontroller after filtering by the high-pass filter circuit; the alternating current signal generating circuit outputs the alternating current voltage signal u, which is divided by the internal resistance measuring reference circuit to obtain an internal resistance measuring reference signal, and outputs the signal to the microcontroller after filtering by the high-pass filter circuit; the microcontroller calculates the internal resistance according to the two received signals.

[0010] Further, the internal resistance is:

[0011]

[0012] Wherein, r is the internal resistance, u1 is the filtered internal resistance measuring reference signal, u2 is the filtered internal resistance measuring signal, and R3 is the reference resistance.

[0013] Further, the AC signal generating circuit outputs an AC voltage signal u to the microcontroller after filtering by the high-pass filter circuit; the microcontroller is further configured to determine whether the AC signal generating circuit reaches an expected stability criterion according to the filtered internal resistance measurement reference signal and the filtered AC voltage signal u, and calculate the internal resistance when the criterion is reached.

[0014] Further, the microcontroller stores a plurality of non-linear characteristic curves between internal resistance and temperature under different working time periods; the microcontroller determines the target temperature value according to the corresponding non-linear characteristic curve and the internal resistance.

[0015] According to another aspect of the present application, a zirconia-based high-temperature sensor control compensation method is provided, comprising: measuring and calculating an internal resistance of the zirconia-based high-temperature sensor; adjusting a target temperature value according to a working time of the zirconia-based high-temperature sensor and the internal resistance, and performing fuzzy PID control according to a deviation value of the internal resistance relative to a reference resistance, thereby outputting a heating control signal; driving a sensor heater according to the heating control signal, so that a temperature of the zirconia-based high-temperature sensor reaches the target temperature value.

[0016] Further, the method further comprises: calculating an internal resistance decay coefficient of the zirconia-based high-temperature sensor, and compensating a sensed voltage of the zirconia-based high-temperature sensor according to the internal resistance decay coefficient.

[0017] Overall, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0018] (1) A zirconia-based high-temperature sensor control compensation circuit is provided, which considers the influence of sensor internal resistance decay temperature control, compensates and corrects the target temperature of temperature control based on the real-time measured internal resistance, improves the accuracy of temperature control, and thus improves the detection accuracy of the sensor;

[0019] (2) The influence of sensor internal resistance decay on sensor detection accuracy is further considered, the sensed voltage of the sensor is compensated and corrected based on the real-time internal resistance decay coefficient, and the detection accuracy of the sensor is further improved;

[0020] (3) The internal resistance measurement adopts a sinusoidal AC signal, realizing synchronous measurement of internal resistance and sensed signal, having universality and being applicable to all zirconia-based solid states, and having a wider application range. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A structure block diagram of a zirconia-based high-temperature sensor control compensation circuit according to an embodiment of the present application is provided;

[0022] Figure 2A circuit diagram of the zirconia-based high-temperature sensor control compensation circuit provided by the embodiment of the present application is shown in the figure.

[0023] Figure 3 A temperature-resistance characteristic relationship curve diagram provided by the embodiment of the present application is shown in the figure.

[0024] In all the figures, the same reference signs are used to indicate the same elements or structures, wherein:

[0025] 1 is an internal resistance measurement unit, 11 is an alternating current signal generation circuit, 12 is an internal resistance measurement reference circuit, 13 is a high-pass filter circuit, 14 is a low-pass filter circuit, 15 is a bias circuit, 2 is a microcontroller, and 3 is a heating drive unit. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] In the present application, the terms "first", "second", etc. (if any) in the present application and the accompanying drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0028] Figure 1 A structure block diagram of the zirconia-based high-temperature sensor control compensation circuit provided by the embodiment of the present application is shown in the figure. Figure 1 , in combination with Figures 2-3 , the zirconia-based high-temperature sensor control compensation circuit in the embodiment is described in detail.

[0029] The zirconia-based high-temperature sensor control compensation circuit includes an internal resistance measurement unit 1, a microcontroller 2 and a heating drive unit 3. The internal resistance measurement unit 1 and the microcontroller 2 work together to measure and calculate the internal resistance of the zirconia-based high-temperature sensor. The microcontroller 2 adjusts the target temperature value according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and performs fuzzy PID control according to the deviation value of the internal resistance relative to the reference resistance, thereby outputting a heating control signal. The heating drive unit 3 drives the sensor heater according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value.

[0030] The zirconia-based high-temperature sensor control compensation circuit in the embodiment, after measuring the internal resistance of the zirconia-based high-temperature sensor in real time, calculates the heater temperature control duty ratio through the fuzzy PID control algorithm, thereby generating a corresponding heating control signal to control the heater.

[0031] According to an embodiment of the present application, the microcontroller 2 stores a plurality of nonlinear characteristic curves of the internal resistance and the temperature under different working time periods, and determines the target temperature value according to the corresponding nonlinear characteristic curve and the internal resistance. That is, the microcontroller 2 selects the corresponding nonlinear characteristic curve according to the working time of the zirconia-based high-temperature sensor, and determines the target temperature value based on the real-time measured internal resistance and the selected nonlinear characteristic curve.

[0032] According to an embodiment of the present application, the microcontroller 2 is further configured to calculate the internal resistance decay coefficient of the zirconia-based high-temperature sensor, and compensate the induced voltage output by the solid electrolyte cell according to the internal resistance decay coefficient.

[0033] The microcontroller 2 calculates the internal resistance decay coefficient of the zirconia-based high-temperature sensor in the following manner: the microcontroller 2 controls the sensor heater to work at the first power P0, and measures the first internal resistance r0 of the zirconia-based high-temperature sensor at the first temperature T0; after working for a set time t1, the microcontroller 2 controls the sensor heater to work at the first power P0, and measures the second internal resistance r1 of the zirconia-based high-temperature sensor at the first temperature T0; the internal resistance decay coefficient a is equal to the ratio of the second internal resistance to the first internal resistance, i.e. r1 / r0.

[0034] The microcontroller 2 stores a corresponding relationship between the internal resistance decay coefficient and the induced voltage compensation amount. The corresponding relationship can be established according to a large amount of experimental data, and the microcontroller 2 compensates the induced voltage output by the zirconia-based high-temperature sensor based on the calculated internal resistance decay coefficient according to the corresponding relationship.

[0035] In the embodiment of the present application, the initial internal resistance-temperature characteristic curve, the internal resistance-temperature characteristic curve after aging, the initial internal resistance-induced voltage characteristic curve, and the internal resistance-induced voltage characteristic curve after aging are established according to the batch characteristics of the zirconia-based high-temperature sensor, as shown in FIG. 1. Figure 3

[0036] V0=f(Re0)

[0037] V1=f(Re1)

[0038] In the initial state of the sensor, the sensor is heated at a specific power P0, and the internal resistance r0 of the solid electrolyte cell is measured. After working for a period of time t1, the sensor is heated at the same power P0, and the internal resistance r1 of the solid electrolyte cell is measured, and the internal resistance decay coefficient a is calculated as a=r1 / r0. According to the temperature resistance and decay characteristic curves shown in FIG. 1, the target temperature value based on the internal resistance is corrected according to the internal resistance decay coefficient a, and the induced voltage output by the solid electrolyte cell is compensated. Figure 3

[0039] ​​The embodiment of the present application also provides a preferred internal resistance measuring unit structure, as shown in Figure 1 and Figure 2 Preferably, the internal resistance measuring unit 1 comprises an alternating current signal generating circuit 11, an internal resistance measuring reference circuit 12 and a high-pass filter circuit 13.

[0040] The alternating current signal generating circuit 11 applies an alternating voltage signal u to the zirconia-based high-temperature sensor to obtain an internal resistance measuring signal and output the signal to the microcontroller 2 after filtering by the high-pass filter circuit 13. The alternating current signal generating circuit 11 outputs the alternating voltage signal u to the microcontroller 2 after voltage division by the internal resistance measuring reference circuit 12, filtering by the high-pass filter circuit 13 and obtaining an internal resistance measuring reference signal. The microcontroller 2 calculates the internal resistance according to the two received signals.

[0041] According to the embodiment of the present application, the measured internal resistance of the zirconia-based high-temperature sensor is:

[0042]

[0043] Wherein, r is the internal resistance, u1 is the filtered internal resistance measuring reference signal, u2 is the filtered internal resistance measuring signal, and R3 is the reference resistance.

[0044] Further preferably, the alternating current signal generating circuit 11 outputs the alternating voltage signal u to the microcontroller 2 after filtering by the high-pass filter circuit 13. The microcontroller 2 is also used to determine whether the alternating current signal generating circuit 11 reaches the expected stability standard according to the filtered internal resistance measuring reference signal and the filtered alternating voltage signal u, and calculate the internal resistance when the expected stability standard is reached. In this way, the accuracy and precision of the calculated internal resistance are ensured.

[0045] Referring to the structure block diagram of the zirconia-based high-temperature sensor control compensation circuit shown in Figure 1 The alternating current signal generating circuit 11 is connected to the electrode of the solid-state electrolyte unit of the zirconia-based high-temperature sensor through a signal line, and loads the alternating voltage signal u through the electrode to measure the internal resistance of the solid-state electrolyte unit, thereby outputting the corresponding internal resistance measuring voltage signal (i.e. the internal resistance measuring signal). The internal resistance measuring voltage signal is divided into two paths and reaches the microcontroller 2 after filtering by the high-pass filter circuit 13 and the low-pass filter circuit 14. All signals are superimposed with a bias voltage by the bias circuit 15 to meet the signal acquisition requirements of the microcontroller 2. The alternating current signal generating circuit 11 is also connected to the internal resistance measuring reference circuit 12. The alternating voltage signal u output by the alternating current signal generating circuit 11 reaches the microcontroller 2 after being filtered by the internal resistance measuring reference circuit and the high-pass filter circuit 13. The microcontroller 2 collects the signals reaching its port through the ADC collection port, calculates the real-time internal resistance, and outputs the real-time heating control signal to the heating driving module after fuzzy PID operation, thereby realizing the temperature control of the sensor.

[0046] As shown in Figure 2 The alternating current signal generating circuit 11 can be designed as a sinusoidal alternating current signal generating circuit, for example, the frequency thereof is set to f = 1 / (2π*R 11 *C1) = 1061 Hz, and the amplitude is set to be less than 5 V, and the setting of the amplitude needs to be matched with the voltage sampling range of the ADC of the microcontroller. The internal resistance measurement reference circuit is composed of, for example, a resistor R2 and a resistor R3, the resistor R3 is connected to the output network VR1 of the bias circuit 15, and the output voltage of the bias circuit is set to, for example, 2.5 V. At the same time, the bias circuit output is connected to the lower electrode of the solid-state electrolyte unit. The sinusoidal alternating current signal passes through the voltage dividing resistor R9 and is connected to the upper electrode of the solid-state electrolyte unit through the output network TEST.

[0047] The high-pass filter circuit 13 has three inputs connected to the output network TEMREF1 of the internal resistance measurement reference circuit, the output network TEST of the internal resistance measurement, and the output network SINE of the alternating current signal generating circuit, respectively, and the real-time peak voltage of the corresponding signal is obtained through data processing and output to three ADC sampling ports of the microcontroller. The input of the low-pass filter circuit is connected to the output network TEST of the internal resistance measurement, and the output is connected to the ADC4 sampling port of the microcontroller. The Nernst induced voltage signal of the solid-state electrolyte unit in the normal working state is obtained through the low-pass filter.

[0048] The filter cutoff frequency needs to be adapted to the frequency of the sinusoidal alternating current signal. In the present embodiment, the cutoff frequency of the high-pass filter circuit is set to, for example, 800 Hz, and the cutoff frequency of the low-pass filter circuit is set to, for example, 31 Hz.

[0049] The zirconia-based high-temperature sensor control compensation circuit provided by the embodiment of the present application realizes the synchronous measurement of the internal resistance and the induced signal by using a sinusoidal alternating current signal, has universality, and can be applied to all zirconia-based solid-state electrolyte units; and the compensation correction of the influence of the sensor internal resistance decay temperature control is realized by using an intelligent method, thereby improving the accuracy of the internal resistance measurement and the temperature control of the sensor and improving the detection accuracy of the sensor.

[0050] The embodiment of the present application also provides a zirconia-based high-temperature sensor control compensation method, which comprises operations S1-S3.

[0051] In operation S1, the internal resistance of the zirconia-based high-temperature sensor is measured and calculated.

[0052] In operation S2, the target temperature value is adjusted according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and the fuzzy PID control is performed according to the deviation value of the internal resistance relative to the reference resistance, so as to output a heating control signal.

[0053] Operation S3, driving the sensor heater according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value.

[0054] According to the embodiment of the present application, the method further comprises: calculating the internal resistance attenuation coefficient of the zirconia-based high-temperature sensor, and compensating the induced voltage measured by the zirconia-based high-temperature sensor according to the internal resistance attenuation coefficient.

[0055] The zirconia-based high-temperature sensor control compensation method in the embodiment is the same as the working principle of the zirconia-based high-temperature sensor control compensation circuit in the embodiment shown in Figures 1-3 The details of the embodiment not covered can be referred to the embodiment shown in Figures 1-3 The zirconia-based high-temperature sensor control compensation circuit in the embodiment.

[0056] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A zirconia-based high temperature sensor control compensation circuit, characterized by, The application relates to a zirconia-based high-temperature sensor, which comprises an internal resistance measuring unit (1), a microcontroller (2) and a heating driving unit (3). The microcontroller (2) adjusts a target temperature value according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and performs fuzzy PID control according to the deviation value of the internal resistance relative to a reference resistance, so as to output a heating control signal; the microcontroller (2) stores a nonlinear characteristic curve between the internal resistance and the temperature in different working time periods; the microcontroller (2) determines the target temperature value according to the corresponding nonlinear characteristic curve and the internal resistance; the microcontroller (2) stores a corresponding relationship between an internal resistance attenuation coefficient and an induced voltage compensation amount, and the microcontroller (2) is further used for calculating the internal resistance attenuation coefficient of the zirconia-based high-temperature sensor and compensating the induced voltage measured by the zirconia-based high-temperature sensor according to the internal resistance attenuation coefficient; wherein the process of calculating the internal resistance attenuation coefficient of the zirconia-based high-temperature sensor comprises the following steps: the microcontroller (2) controls a sensor heater to work at a first power, and measures a first internal resistance of the zirconia-based high-temperature sensor at a first temperature; after a working setting time, the microcontroller (2) controls the sensor heater to work at the first power, and measures a second internal resistance of the zirconia-based high-temperature sensor at the first temperature; the internal resistance attenuation coefficient is equal to the ratio of the second internal resistance to the first internal resistance; The internal resistance measuring unit (1) and the microcontroller (2) work together to measure and calculate the internal resistance of the zirconia-based high-temperature sensor; the internal resistance measuring unit (1) comprises an alternating current signal generating circuit (11), an internal resistance measuring reference circuit (12) and a high-pass filter circuit (13); the alternating current signal generating circuit (11) applies an alternating current voltage signal to the zirconia-based high-temperature sensor, obtains an internal resistance measuring signal, and outputs the signal to the microcontroller (2) after filtering by the high-pass filter circuit (13); the alternating current signal generating circuit (11) outputs an alternating current voltage signal divided by the internal resistance measuring reference circuit (12), obtains an internal resistance measuring reference signal, and outputs the signal to the microcontroller (2) after filtering by the high-pass filter circuit (13); the microcontroller (2) calculates the internal resistance according to the two received signals; the internal resistance measurement adopts a sinusoidal alternating current signal, realizing synchronous measurement of the internal resistance and the induced signal; The heating driving unit (3) drives the sensor heater according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value. The internal resistance is:

2. The zirconia-based high temperature sensor control compensation circuit of claim 1, wherein, The application relates to a zirconia-based high-temperature sensor, which comprises an internal resistance measuring unit (1), a microcontroller (2) and a heating driving unit (3). wherein, is the internal resistance, is the filtered internal resistance measurement reference signal, is the filtered internal resistance measurement signal, is the reference resistance.

3. The zirconia-based high temperature sensor control compensation circuit according to claim 1 or 2, characterized in that The alternating current signal generating circuit (11) outputs an alternating voltage signal After filtering by the high-pass filter circuit (13), output to the microcontroller (2) The microcontroller (2) is further configured to determine whether the AC signal generation circuit (11) has reached an expected stability criterion and, when it has, to calculate the internal resistance from the filtered internal resistance measurement reference signal and the filtered AC voltage signal determine whether the AC signal generation circuit (11) has reached an expected stability criterion and, when it has, to calculate the internal resistance.

4. A zirconia-based high temperature sensor control compensation method for controlling a compensation circuit of a zirconia-based high temperature sensor based on any one of claims 1 to 3, characterized by, The internal resistance of the zirconia-based high-temperature sensor is measured and calculated; The target temperature value is adjusted according to the working time of the zirconia-based high-temperature sensor and the internal resistance, and fuzzy PID control is performed according to the deviation value of the internal resistance relative to a reference resistance, so as to output a heating control signal; The sensor heater is driven according to the heating control signal, so that the temperature of the zirconia-based high-temperature sensor reaches the target temperature value; The internal resistance attenuation coefficient of the zirconia-based high-temperature sensor is calculated, and the induced voltage measured by the zirconia-based high-temperature sensor is compensated according to the internal resistance attenuation coefficient. ​

Images