Wide-range oxygen sensor controller

Abstract

The utility model relates to the technical field of sensors, in particular to a wide-range oxygen sensor controller. The wide-range oxygen sensor controller comprises a micro-control unit, a heating drive circuit, a Nernst voltage detection circuit, a pump voltage acquisition circuit, a constant current source circuit, an internal resistance measurement circuit, a CAN communication circuit, a power supply circuit and a DAC module, the device is characterized in that a pin 8 of the micro-control unit is connected with a pump voltage acquisition circuit, a pin 9 of the micro-control unit is connected with a Nernst voltage detection circuit, a pin 10 of the micro-control unit is connected with a heating drive circuit, a pin 15 of the micro-control unit is connected with a CAN communication circuit, a pin 18 of the micro-control unit is connected with a DAC module, a pin 11 and a pin 12 of the micro-control unit are connected with an internal resistance measuring circuit, and the internal resistance measuring circuit and a constant current source circuit are connected to a wide-range oxygen sensor. And the CAN communication circuit is connected to upper computer software. And real-time data can be sent to demanders, so that the practicability and the reliability are improved.

Description

Technical Field

[0001] The utility model relates to a controller, in particular to a wide-range oxygen sensor controller. Background Art

[0002] With the rapid development of the global economy, cars have become an indispensable means of transportation in daily life, but existing exhaust gas treatment technologies still have some shortcomings.

[0003] To effectively reduce emissions of these pollutants, governments and international organizations around the world have enacted strict emissions regulations, driving the development of automotive emission control technologies. Wideband oxygen sensors, which continuously measure exhaust oxygen concentration, are widely used in engine air-fuel ratio control systems. They adjust fuel injection or air supply to maintain an ideal air-fuel ratio, optimize combustion efficiency, and reduce harmful emissions. Furthermore, as exhaust emission standards continue to improve, the performance requirements for controllers are also increasing. For example, increasingly lower NOx emission limits require controllers to perform more precise adjustments, resulting in increasingly higher controller purchase costs. Therefore, developing a low-cost, high-efficiency wideband oxygen sensor controller to improve vehicle exhaust treatment efficiency is of great significance for improving environmental quality, promoting human health, and promoting the sustainable development of the automotive industry. Utility Model Content

[0004] The utility model aims to solve the above-mentioned defects and provides a wide-range oxygen sensor controller.

[0005] In order to overcome the defects existing in the background technology, the technical solution adopted by the present invention to solve its technical problems is: this wide-range oxygen sensor controller includes a microcontroller unit, a heating drive circuit, a Nernst voltage detection circuit, a pump voltage acquisition circuit, a constant current source circuit, an internal resistance measurement circuit, a CAN communication circuit, a power supply circuit and a DAC module, characterized in that: pin 8 of the microcontroller unit is connected to the pump voltage acquisition circuit, pin 9 is connected to the Nernst voltage detection circuit, pin 10 is connected to the heating drive circuit, pin 15 is connected to the CAN communication circuit, and pin 18 is connected to the DAC module, pins 11 and 12 of the microcontroller unit are connected to the internal resistance measurement circuit, the internal resistance measurement circuit and the constant current source circuit are connected to the wide-range oxygen sensor, and the CAN communication circuit is connected to the host computer software.

[0006] According to another embodiment of the present invention, the wide-range oxygen sensor further includes an oxygen concentration detection unit, a pump unit and a diffusion barrier layer composited on the upper surface of the pump unit, the oxygen concentration detection unit is provided with a heating element and a reference chamber, the pump unit is provided with a diffusion chamber, diffusion holes are provided from the diffusion chamber to the diffusion barrier layer, an external electrode is provided on the diffusion barrier layer, a reference electrode is provided in the reference chamber, and an internal electrode is provided at the lower end of the diffusion chamber.

[0007] According to another embodiment of the present utility model, the constant current source circuit further includes dual operation U1.1, dual operation U1.2, resistors R1, R2, R3, R4, and R5 forming a feedback loop, end 1 of the dual operation U1.1 is connected to one end of the resistor R1 and the resistor R3, end 2 of the dual operation U1.1 is connected to one end of the resistor R2 and the resistor R5, the other end of the resistor R3 is connected to end 3 of the dual operation U1.1 and one end of the resistor R4, the other end of the resistor R5 is connected to end 1 and end 3 of the dual operation U1.2, and the other end of the resistor R4 is connected to end 2 of the dual operation U1.2.

[0008] According to another embodiment of the present invention, the heating drive circuit further includes an NPN transistor Q1, a PNP transistor Q2, an NMOS transistor Q3 and resistors R6, R7 and R8, the bases of the NPN transistor Q1 and the PNP transistor Q2 are connected to the resistor R6, the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected and connected to one end of the resistor R7, the other end of the resistor R7 is connected to one end of the resistor R8 and one end of the NMOS transistor Q3, the three ends of the NMOS transistor Q3 are connected to the heating element, and the two ends of the NMOS transistor Q3 are grounded.

[0009] According to another embodiment of the present utility model, the pump voltage acquisition circuit further includes an operational amplifier U1.3, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, and a resistor R14. End 2 of the operational amplifier U1.3 is connected to the resistor R9, the resistor R11, and one end of the capacitor C1. End 3 of the operational amplifier U1.3 is connected to the resistor R10, the resistor R13, and one end of the capacitor C2. The other end of the resistor R9 is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the other end of the resistor R10. The other ends of the resistor R11 and the capacitor C1 are connected to the resistor R12 and end 1 of the operational amplifier U1.3.

[0010] The present invention provides the following beneficial effects: The pump voltage acquisition circuit of this wide-band oxygen sensor controller utilizes a differential operational amplifier. The addition of a capacitor effectively suppresses common-mode noise at the input, reduces interference, and improves signal stability. A reference bias voltage is added to enhance the acquisition accuracy of the microcontroller's ADC. A PID algorithm calculates the actual Nernst voltage Es against its ideal value. The microcontroller's DAC adjusts the pump voltage Vp output based on the signal output from the PID calculation, thereby changing the pump current Ip. After amplification by the differential operational amplifier circuit, the signal is processed within the microcontroller, and the output pump voltage Vp is applied to the electrodes within the wide-band oxygen sensor. This entire control process forms a complete feedback system. Pump current Ip is an important indicator for evaluating the air-fuel ratio λ and is determined by pump voltage Vp. Accurately controlling pump voltage Vp through the feedback system indirectly improves controller performance and accuracy, enabling a more accurate air-fuel ratio λ. The controller integrates a CAN communication circuit for communication with a host computer, enabling real-time data transmission to those requesting it, enhancing practicality and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0012] Figure 1 A schematic block diagram of the hardware structure of a wide-band oxygen sensor controller provided by an embodiment of the present invention;

[0013] Figure 2 A schematic diagram of the internal structure of a wide-band oxygen sensor provided by an embodiment of the present invention;

[0014] Figure 3 A schematic diagram of a constant current source driving circuit according to an embodiment of the present invention;

[0015] Figure 4 A schematic diagram of a heating drive circuit provided in an embodiment of the present invention;

[0016] Figure 5 Schematic diagram of the pump voltage acquisition circuit provided by an embodiment of the present invention;

[0017] Figure 6 A schematic diagram of the timing of measuring internal resistance with positive and negative pulses provided in an embodiment of the present invention;

[0018] Figure 7 This is a diagram of the host computer communication system interface provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, but not all of them. The embodiments of the basic utility model and all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present utility model.

[0020] A wide-range oxygen sensor controller, such as Figure 1 As shown, it includes a microcontroller unit, a heating drive circuit, a Nernst voltage detection circuit, a pump voltage acquisition circuit, a constant current source circuit, an internal resistance measurement circuit, a CAN communication circuit, a power supply circuit and a DAC module. Pin 8 of the microcontroller unit is connected to the pump voltage acquisition circuit, pin 9 is connected to the Nernst voltage detection circuit, pin 10 is connected to the heating drive circuit, pin 15 is connected to the CAN communication circuit, and pin 18 is connected to the DAC module. Pins 11 and 12 of the microcontroller unit are connected to the internal resistance measurement circuit. The internal resistance measurement circuit and the constant current source circuit are connected to the wide-range oxygen sensor, and the CAN communication circuit is connected to the host computer software.

[0021] Wide-band oxygen sensors such as Figure 2 As shown, the system includes an oxygen concentration detection unit 10, a pump unit 5, and a diffusion barrier layer 1 composited onto the upper surface of the pump unit 5. The oxygen concentration detection unit 10 is equipped with a heating element 6 and a reference chamber 8. The pump unit 5 is provided with a diffusion chamber 4. Diffusion holes 3 are provided between the diffusion chamber 4 and the diffusion barrier layer 1. The diffusion barrier layer 1 is provided with an external electrode 2. The reference chamber 8 is provided with a reference electrode 7. The lower end of the diffusion chamber 4 is provided with an internal electrode 9. When oxygen is pumped into or out of the diffusion chamber, the diffusion chamber side serves as the cathode of the pump cell, while the exhaust side serves as the anode of the pump cell. As the oxygen pump element pumps oxygen ions into or out of the diffusion chamber, a saturated pump current Ip is generated in the circuit. The pump voltage Vp is detected by the pump voltage acquisition circuit, and the pump current Ip of the pump unit control circuit is calculated based on the sense resistor. The direction and magnitude of the Ip current accurately reflect the richness or leanness of the mixture and the specific air-fuel ratio λ.

[0022] The microcontroller unit is used to generate PWM pulse width modulation signals to control the heating drive circuit, collect ADC voltage signals and DAC voltage control signals, and communicate with the host computer.

[0023] Heating drive circuit, according to the internal resistance R h Adjust the output control signal of the microcontroller unit and output the control signal to the heating control circuit port. By heating the internal heating element of the wide-range oxygen sensor, the oxygen ion activity is maximized and the wide-range oxygen sensor works best. After that, the temperature control of the internal heating element enters the closed-loop control stage.

[0024] The internal resistance measurement circuit uses a microcontroller to control the pulse level state of its IO port I_Test, generating positive and negative pulse currents I+ and I-, which are passed into the oxygen sensor. The microcontroller collects the voltage values ​​V+ and V- through the ADC port, stores them in internal registers, and calculates the internal resistance of the wide-band oxygen sensor based on the positive and negative pulse current values ​​I+ and I-. Because the wide-band oxygen sensor's oxygen concentration detection unit has an oxygen pumping characteristic, applying an external signal to measure the internal resistance produces an oxygen pumping effect, i.e., oxygen ions are pumped in and out, changing the oxygen concentration within the diffusion chamber and affecting detection accuracy. To counteract this oxygen pumping effect, a method of passing positive and negative pulse currents, namely the AC voltage drop method, is used. This method maintains the oxygen concentration within the diffusion chamber as unaffected as possible, improving measurement accuracy. The moment positive and negative pulse currents I+ and I- are applied, oxygen pumping occurs—that is, oxygen ions are pumped in and out. This affects the magnitude of the detection current. To obtain relatively accurate detection currents, the pulse currents I+ and I- should be calculated very quickly after the positive and negative pulse currents are applied. Furthermore, the wide-band oxygen sensor should avoid prolonged continuous oxygen pumping. Continuous oxygen ion pumping can increase the voltage difference between the inner electrode and the reference electrode, potentially leading to electrode plate breakdown. To address this issue, a 5kHz pulse measurement level with a 200µs period is output from the microcontroller's IO pin I_Test. The high and low levels each last 100µs, generating positive and negative pulse currents. A high-precision resistor is connected in series to form a current path, facilitating pulse current measurement. When the microcontroller's IO pin I_Test outputs a high level, a 100µs positive pulse current I+ is generated and passed into the wide-band oxygen sensor. When the microcontroller's IO pin I_Test outputs a low level, a 100µs negative pulse current I- is generated and passed out of the wide-band oxygen sensor. When positive and negative pulse currents I+ and I- are applied, the voltage values ​​V+ and V- are collected by the ADC of the microcontroller unit and stored in the register. The pulse current value is calculated based on the value of the series high-precision resistor. The ratio of the sum of the absolute values ​​of the voltage to the absolute value of the current is the internal resistance value.

[0025] The constant current source circuit, using a precision op amp to form a feedback loop, generates a 22μA constant current Ir that acts on the anode of the wide-band oxygen sensor's internal oxygen concentration detection unit, ensuring a constant oxygen concentration within the reference chamber. Due to the harsh and volatile ambient conditions of wide-band oxygen sensors in automotive exhaust treatment systems, this circuit utilizes two op amps and multiple resistors of varying resistance to form a closed-loop feedback control circuit. This circuit controls the state of the microcontroller's IO pin, I_Ref, to achieve a constant current Ir output, ensuring a stable oxygen concentration within the sensor's internal reference chamber.

[0026] The pump voltage acquisition circuit uses a differential operational amplifier to generate voltages Vin0+ and Vin0- across the wide-range oxygen sensor controller output port after passing through a high-precision sense resistor. To improve pump voltage acquisition accuracy, a bias voltage is added to prevent the voltage signal from being too small, which could affect the ADC acquisition accuracy. The microcontroller collects voltage signal Uo through the ADC port. The microcontroller makes judgments based on the collected voltage signals and ultimately controls the DAC module to output a pump voltage Vp, which is applied to the wide-range oxygen sensor's external electrodes for control. The pump voltage acquisition circuit uses a differential operational amplifier to generate voltages Vin0+ and Vin0- across the wide-range oxygen sensor controller output port after passing through a high-precision sense resistor. These voltages are then connected to the non-inverting and inverting inputs of the operational amplifier for differential amplification. To improve pump voltage acquisition accuracy, a reference bias voltage V_M is added to the non-inverting input of the operational amplifier. The amplified voltage Uo is finally acquired by the microcontroller's ADC. The microcontroller then calculates the actual pump voltage Vp based on the differential amplifier circuit multiplier A and the bias voltage V_M. And according to other voltage signals collected by the ADC of the microcontroller unit, judgment is made, and finally the microcontroller unit controls the DAC module to output the pump voltage Vp to act on the outer electrode of the wide-range oxygen sensor.

[0027] In order to realize the communication between the wide-range oxygen sensor controller and the host computer and improve the reliability of data transmission, the CAN communication circuit is integrated on the control board.

[0028] The microcontroller's ADC collects other voltage signals: The difference in oxygen concentration between the diffusion chamber within the wide-band oxygen sensor and the air in the reference chamber generates an electromotive force (Vref) between the inner and outer electrodes. The microcontroller's ADC collects this voltage signal and subtracts it from the reference bias voltage (V_M) to obtain the Nernst voltage Es. The Nernst voltage reflects the real-time oxygen concentration within the wide-band oxygen sensor's chamber. Es indicates the richness or leanness of the combustible gas mixture. Due to the unique internal structure of the wide-band oxygen sensor, the Nernst voltage Es must be carefully considered when setting its reference value. If the reference value is too large, the amount of oxygen pumped into the diffusion chamber increases, raising the oxygen ion concentration. The voltage difference between the inner and reference electrodes is excessive, potentially causing breakdown of the electrodes. If the reference value is too small, the oxygen ion concentration within the diffusion chamber is low, resulting in a low pump current (Ip), affecting detection accuracy. Based on these considerations and analysis of multiple experimental results, the Nernst reference Es was set to 450mV for control purposes. When Es>450mV, the mixture is rich. At this time, after the PID calculation link inside the microcontroller, the microcontroller controls the DAC module to output the pump voltage Vp to the outer electrode of the wide-range oxygen sensor, and the external oxygen is pumped into the diffusion chamber to form a reverse pump current signal Ip; when Es<450mV, the mixture is lean. At this time, after the PID calculation link inside the microcontroller, the microcontroller controls the DAC module to output the pump voltage Vp to the outer electrode of the wide-range oxygen sensor, and the oxygen in the diffusion chamber is pumped out to form a forward pump current signal Ip, until Es=450mV.

[0029] The microcontroller unit's ADC data acquisition and PID calculations are performed 50µs after the positive and negative pulses for internal resistance measurement are applied. Since the wide-band oxygen sensor experiences oxygen pumping after the positive and negative pulses are applied, a 50µs wait is required for the diffusion chamber to stabilize before proceeding, ensuring maximum data acquisition and control accuracy. After 50µs, data acquisition and control are performed over 10 cycles (2000µs). Multiple ADC acquisitions ensure accurate results, and internal resistance measurement is repeated 2000µs later to achieve repeatable, precise control.

[0030] like Figure 1As shown, by configuring the microcontroller unit IO port 12 to output a 5KHZ pulse measurement level, the period of which is 200us. The duration of the high and low levels is 100us respectively, generating positive and negative pulse currents I+ and I-, and a high-precision resistor is connected in series to form a current path. When the microcontroller unit 12 outputs a pulse high level to the internal resistance measurement circuit, a positive pulse current path is formed with the 4-pin of the wide-range oxygen sensor. The voltage value V+ at the internal resistance end of the wide-range oxygen sensor is collected through the ADC port 9 of the microcontroller unit and stored in the register of the microcontroller unit. When the microcontroller unit 12 outputs a pulse low level to the internal resistance measurement circuit, the current flows from the wide-range oxygen sensor to the 12-end of the microcontroller unit, forming a negative pulse current path. The voltage value V- at the internal resistance end of the wide-range oxygen sensor is collected through the ADC port 9 of the microcontroller unit and stored in the register of the microcontroller unit. At this time, an internal resistance measurement is completed. The timing diagram of the positive and negative pulse measurement of internal resistance is shown as follows. Figure 6 As shown, when a high level pulse is input, Figure 6 At the current curve 1 shown, the voltage value V+ is collected at the highest current point. At this time, the oxygen ion concentration inside the sensor changes little and the measurement result is relatively accurate. Figure 6 At the current curve 2 shown, the voltage value V- is collected at the lowest point of the current. At this time, the oxygen ion concentration inside the sensor changes little, and the measurement result is relatively accurate. The pulse current value is calculated according to the series resistance value of the internal resistance measurement circuit. The ratio of the sum of the absolute values ​​of the voltage collected twice to the calculated absolute value of the current is the internal resistance value R. h .

[0031] According to the internal resistance R on both sides of the zirconia inside the wide-range oxygen sensor h The microcontroller controls the PWM port 10 to drive the heating drive circuit, such as Figure 4 As shown, the heating drive circuit consists of an NPN transistor Q1, a PNP transistor Q2, an NMOS transistor Q3, and resistors R6, R7, and R8. R6 and R7 are current limiting resistors. The bases of the NPN transistors Q1 and PNP transistors Q2 are connected to resistor R6. The emitters of the NPN transistors Q1 and PNP transistors Q2 are connected and connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R8 and terminal 1 of the NMOS transistor Q3. Terminal 3 of the NMOS transistor Q3 is connected to the heating element, and terminal 2 of the NMOS transistor Q3 is grounded. R8 provides a fast energy discharge circuit when the NMOS transistor Q3 is turned off. The microcontroller unit adjusts the internal resistance value R h The PWM output duty cycle is adjusted by the microcontroller unit. When the heating drive circuit receives the PWM signal, the high-level state NPN transistor Q1 is turned on. At this time, VCC2 (5V) outputs voltage to the gate of the NMOS tube Q3 through the resistor R7. At this time, the NMOS tube is turned on, and the heating element is connected to Figure 1As shown, the wide-band oxygen sensor port 5 and the wide-band oxygen sensor port 6 are connected to VCC1 (24V) to form a complete heating circuit. When the PWM signal is low, the PNP transistor Q2 is turned on. At this time, the gate of the NMOS transistor Q3 passes through the resistor R7 and Q2 to the ground, forming an energy discharge circuit, so that the NMOS transistor Q3 is quickly turned off to reduce energy loss. In order to avoid the following during the heating process Figure 2 The 5-pin heating element shown is damaged. Multi-stage heating is used. Due to the internal resistance R h The internal resistance value R h The higher the value, the lower the temperature. h When the duty cycle of the PWM pulse width modulation signal output by the microcontroller port 10 is relatively low, the internal resistance value R is detected at regular intervals. h Changes, adjust the PWM output duty cycle. h As the PWM signal's duty cycle approaches the ideal value, it gradually stabilizes and maintains its current duty cycle, thereby stabilizing the zirconium oxide temperature. This heating method prevents damage to the wide-band oxygen sensor and extends its service life. The microcontroller uses a KBI module to detect the falling edge of the PWM output. When this is detected, an interrupt request (IRQ) is triggered, executing other command requests and improving the microcontroller's operating efficiency.

[0032] Constant current source circuit such as Figure 3 As shown, a feedback loop is precisely formed by dual operation U1.1, U1.2, resistors R1, R2, R3, R4, and R5. Terminal 1 of dual operation U1.1 is connected to one end of resistor R1 and resistor R3, terminal 2 of dual operation U1.1 is connected to one end of resistor R2 and resistor R5, the other end of resistor R3 is connected to terminal 3 of dual operation U1.1 and one end of resistor R4, the other end of resistor R5 is connected to terminal 1 and terminal 3 of dual operation U1.2, and the other end of resistor R4 is connected to terminal 2 of dual operation U1.2. Figure 1 The microcontroller pin 7 outputs a 5V constant voltage I_Ref, which generates a 22μA constant current Ir. Figure 2 The 7-pin wideband oxygen sensor shown in the figure has an internal reference electrode to ensure a constant oxygen concentration in the reference chamber, which helps improve the accuracy of oxygen concentration measurement. Operational amplifiers U1.1 and U1.2 are powered by VCC2 (5V). The current Ir is calculated using the formula based on the basic principle of op amps:

[0033]

[0034] Pump voltage acquisition circuit, such as Figure 5As shown, it is composed of an operational amplifier U1.3, resistors R9, R10, R11, R12, R13, and R14. The two ends of the operational amplifier U1.3 are connected to the resistor R9, the resistor R11, and one end of the capacitor C1. The three ends of the operational amplifier U1.3 are connected to the resistor R10, the resistor R13, and one end of the capacitor C2. The other end of the resistor R9 is connected to one end of the resistor R14, and the other end of the resistor R14 is connected to the other end of the resistor R10. The other ends of the resistor R11 and the capacitor C1 are connected to the resistor R12 and the one end of the operational amplifier U1.3. Figure 1 The pump current signal output from pins 1 and 2 of the wideband oxygen sensor shown in the figure flows through Figure 5 After the high-precision resistor R14, the differential amplification is performed by the operational amplifier to obtain the output voltage Uo. Figure 6 As shown in the figure, after the internal resistance measurement is completed for 50us, the subsequent control is carried out after the oxygen ion concentration inside the sensor is relatively balanced, which is carried out within 10 cycles of 2000us. Figure 1 The ADC port 8 of the microcontroller unit shown collects the amplified voltage Uo. The microcontroller unit calculates the actual pump voltage Vp based on the differential amplifier circuit multiple A and the bias voltage V_M value. The expression of Uo is:

[0035]

[0036] like Figure 2 The oxygen concentration in the diffusion chamber of the wide-band oxygen sensor shown is different from the oxygen concentration in the air in the reference chamber. The outer electrode and the inner electrode will generate an electromotive force Vref. Figure 1 The wide-range oxygen sensor 4-pin output, the microcontroller ADC collects this voltage signal and Figure 1 The Nernst voltage Es is obtained by taking the difference between the reference bias voltage V_M and the voltage signal collected at the 3rd pin of the wide-band oxygen sensor. The Nernst voltage reflects the real-time oxygen concentration of the internal chamber of the wide-band oxygen sensor. The rich or lean state of the combustible gas mixture can be known according to Es. The control is carried out according to the set Nernst voltage reference value of 450mV. If Es>450mV, it is a rich state. At this time, after the PID operation link inside the microcontroller, the microcontroller controls the DAC module to output the pump voltage Vp and applies it to Figure 2 The wide-band oxygen sensor outer electrode shown in the figure, the external oxygen is pumped into the diffusion chamber, forming a reverse pump current Ip; when Es<450mV, it is a lean state, at this time the microcontroller unit controls the DAC module to output the pump voltage Vp after the PID operation link, and applies it to Figure 2 The outer electrode of the wide-band oxygen sensor shown in the figure pumps out the oxygen in the diffusion chamber, forming a forward pump current Ip until Es = 450mV.

[0037] During the entire control process, the microcontroller ADC collects the Vref and V_M voltage signals in real time, calculates the Nernst voltage signal Es, and uses the PID algorithm to control the DAC module to output the pump voltage Vp, which is then passed through the detection resistor to generate the pump current Ip, thus forming an effective feedback control system. Figure 5 As shown, capacitor C1 is connected in parallel with the op amp's inverting input and output terminals to form a low-pass filter, effectively filtering out high-frequency noise and preventing interference with subsequent circuits. Bias resistor R13, connected in parallel with capacitor C2, stabilizes the voltage signal, ensures accurate ADC acquisition, and improves signal stability. The addition of a reference bias voltage, V_M, prevents the differential amplification voltage, Uo, from being too small after the pump current, Ip, passes through the sense resistor, leading to inaccurate ADC acquisition by the microcontroller unit.

[0038] The microcontroller controls the DAC module to output the pump voltage Vp and applies it to the Figure 2 The outer electrode shown controls the pumping of oxygen into and out of the diffusion chamber. The diffusion chamber side serves as the pump cell's cathode, while the exhaust side serves as the pump cell's anode. As the pump cell pumps oxygen ions into and out of the diffusion chamber, a saturated pump current Ip is generated in the circuit. The pump voltage Vp is detected by the pump voltage acquisition circuit, and the pump current Ip in the pump cell control circuit is calculated based on the sense resistor. The direction and magnitude of the Ip current accurately reflect the richness or leanness of the mixture and the specific air-fuel ratio.

[0039] Pump current Ip is an important indicator for judging the air-fuel ratio λ. Pump current Ip is determined by pump voltage Vp. Accurately controlling pump voltage Vp through the feedback system indirectly improves the performance and accuracy of the controller, and can obtain a more accurate air-fuel ratio λ. The controller integrates CAN communication circuit through Figure 1 As shown in Figure 16 and 17, the host computer communicates with the host computer. The host computer interface is as follows Figure 7 As shown in the figure, we can see the voltage signal Uo after the pump current Ip is amplified, and the pump voltage Vp, pump current Ip, Nernst voltage Es, and internal resistance R on both sides of the zirconia are obtained through conversion. h , oxygen concentration value O2(%), PWM duty cycle value, and heating phase can be provided for real-time reference and analysis by demand personnel, increasing practicality and reliability.

[0040] The above embodiments are preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the above embodiments. Any modifications and partial replacements made within the knowledge of ordinary technicians in this field without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A wide-band oxygen sensor controller, comprising a microcontroller unit, a heating drive circuit, a Nernst voltage detection circuit, a pump voltage acquisition circuit, a constant current source circuit, an internal resistance measurement circuit, a CAN communication circuit, a power supply circuit, and a DAC module, characterized in that: Pin 8 of the microcontroller unit is connected to the pump voltage acquisition circuit, pin 9 is connected to the Nernst voltage detection circuit, pin 10 is connected to the heating drive circuit, pin 15 is connected to the CAN communication circuit, and pin 18 is connected to the DAC module. Pins 11 and 12 of the microcontroller unit are connected to the internal resistance measurement circuit, the internal resistance measurement circuit and the constant current source circuit are connected to the wide-range oxygen sensor, and the CAN communication circuit is connected to the host computer software.

2. The wide-band oxygen sensor controller according to claim 1, characterized in that: The wide-range oxygen sensor comprises an oxygen concentration detection unit (10), a pump unit (5), and a diffusion barrier layer (1) composited on the upper surface of the pump unit (5); a heating element (6) and a reference chamber (8) are provided in the oxygen concentration detection unit (10); a diffusion chamber (4) is provided at the pump unit (5); a diffusion pore (3) is provided from the diffusion chamber (4) to the diffusion barrier layer (1); an external electrode (2) is provided on the diffusion barrier layer (1); a reference electrode (7) is provided in the reference chamber (8); and an internal electrode (9) is provided at the lower end of the diffusion chamber (4).

3. The wide-band oxygen sensor controller according to claim 1, wherein: The constant current source circuit includes dual operation U1.1 and dual operation U1.2, and resistors R1, R2, R3, R4, and R5 form a feedback loop. End 1 of the dual operation U1.1 is connected to one end of the resistor R1 and the resistor R3, end 2 of the dual operation U1.1 is connected to one end of the resistor R2 and the resistor R5, the other end of the resistor R3 is connected to end 3 of the dual operation U1.1 and one end of the resistor R4, the other end of the resistor R5 is connected to end 1 and end 3 of the dual operation U1.2, and the other end of the resistor R4 is connected to end 2 of the dual operation U1.

2.

4. The wide-band oxygen sensor controller according to claim 1, wherein: The heating drive circuit includes an NPN transistor Q1, a PNP transistor Q2, an NMOS transistor Q3 and resistors R6, R7 and R8. The bases of the NPN transistor Q1 and the PNP transistor Q2 are connected to the resistor R6, the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected and connected to one end of the resistor R7, the other end of the resistor R7 is connected to one end of the resistor R8 and one end of the NMOS transistor Q3, the three ends of the NMOS transistor Q3 are connected to the heating element, and the two ends of the NMOS transistor Q3 are grounded.

5. The wide-band oxygen sensor controller according to claim 1, wherein: The pump voltage acquisition circuit includes an operational amplifier U1.3, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, and a resistor R14. End 2 of the operational amplifier U1.3 is connected to the resistor R9, the resistor R11, and one end of the capacitor C1. End 3 of the operational amplifier U1.3 is connected to the resistor R10, the resistor R13, and one end of the capacitor C2. The other end of the resistor R9 is connected to one end of the resistor R14, the other end of the resistor R14 is connected to the other end of the resistor R10, and the other end of the resistor R11 and the capacitor C1 is connected to the resistor R12 and end 1 of the operational amplifier U1.3.

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