High frequency injection-based oxygen sensor internal resistor detection circuit

A technology of oxygen sensor and high-frequency injection, which is applied in the direction of measuring electrical variables, measuring resistance/reactance/impedance, instruments, etc., can solve problems such as inability to measure in real time, and achieve real-time detection and optimize the effect of output voltage

Pending Publication Date: 2017-07-07

凯晟动力技术(嘉兴)有限公司

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Problems solved by technology

Because it will change the output signal amplitude of the oxygen sensor, the original measurement method can on...

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Abstract

The present invention proposes a detection circuit for the internal resistance of an oxygen sensor based on high-frequency injection, including a high-frequency signal shaping circuit, a frequency-voltage conversion circuit, and a power supply module that supplies power to the detection circuit, wherein the high-frequency signal input is high A high-frequency signal shaping circuit, the output end of the high-frequency signal shaping circuit is electrically connected to the input end of the frequency-voltage conversion circuit, and the output end of the frequency-voltage conversion circuit outputs a voltage signal amplitude corresponding to the internal resistance Ri of the oxygen sensor; The frequency-to-voltage conversion circuit is electrically connected to the internal resistance Ri of the oxygen sensor. The detection circuit of the internal resistance of the oxygen sensor based on high-frequency injection provided by the present invention can accurately determine the internal resistance of the oxygen sensor by detecting the internal resistance of the oxygen sensor in real time, optimize the output voltage of the oxygen sensor, and then accurately calculate the air-fuel ratio .

Application Domain

Resistance/reactance/impedence

Technology Topic

Air–fuel ratioEngineering +6

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Examples

Experimental program(1)

Example Embodiment

[0025] Example

[0026] Such as Figure 1-2 As shown, a detection circuit for the internal resistance of an oxygen sensor based on high-frequency injection includes a high-frequency signal shaping circuit 10, a frequency-voltage conversion circuit 20, a feedback loop 30, an internal resistance of the oxygen sensor Ri50, and a power supply for the detection circuit Module VDD40, the high-frequency signal is input to the high-frequency signal shaping circuit 10, the output end of the high-frequency signal shaping circuit 10 is electrically connected to the input end of the frequency-voltage conversion circuit 20, and the frequency-voltage conversion circuit 20 is connected to the oxygen sensor The resistor Ri50 is electrically connected, and the output end of the frequency-voltage conversion circuit 20 is electrically connected to the input end of the feedback loop 30.

[0027] In the above circuit:

[0028] High-frequency signal shaping circuit 10: for receiving high-frequency signals and shaping the high-frequency signals, and then forming a standard high-frequency injection signal;

[0029] Frequency-to-volt conversion circuit 20: used to convert the injected high-frequency signal into a voltage signal, and the magnitude of the voltage signal changes with the change in the internal resistance Ri of the oxygen sensor; the frequency-to-volt conversion circuit converts the injected high-frequency test signal into a The measured voltage signal, the size of this voltage signal is determined by the internal resistance of the oxygen sensor.

[0030] Feedback loop 30: The feedback loop is used to amplify the power of the voltage signal. Since the amplitude of the voltage signal generated by the frequency-to-volt conversion circuit is too small, the feedback amplifier circuit needs to reshape and amplify this signal by dozens of times to obtain a voltage value in the range of 0-5V, which is further convenient for sampling.

[0031] The above-mentioned high-frequency signal shaping circuit 10 includes a first-order filter circuit module 11, a voltage divider circuit module 12, and a common mode disturbance module 13 for suppressing high frequency. The high-frequency signal is input to the first-order filter circuit module 11, and the first-order filter circuit The output end of the module 11 is connected to the input end of the voltage divider circuit module 12, and the output end of the voltage divider circuit module 12 is connected to the input end of the high frequency suppression common mode disturbance module 13, which suppresses high frequency common mode disturbance The output terminal of the module 13 is connected to the input terminal of the frequency-voltage conversion circuit 20.

[0032] The aforementioned first-order filter circuit module 11 includes a sixth resistor R6, a seventh resistor R7, a voltage regulator tube Z, and a fourth capacitor C4. One end of the fourth capacitor C4 is connected to the sixth resistor R6 and the seventh resistor R7, and the other end Grounding; one end of the voltage regulator tube Z is connected to the sixth resistor R6 and the seventh resistor R7, and the other end is grounded.

[0033] The voltage divider circuit module 12 includes a fourth resistor R4 and a fifth resistor R5. The negative input terminal of the first operational amplifier U1 is connected to the fourth resistor R4 and the fifth resistor R5, respectively. The input negative terminal of the first operational amplifier U1 is The terminal is grounded through the fifth resistor R5.

[0034] The above-mentioned common mode disturbance module 13 for suppressing high frequency includes a third capacitor C3 and a first operational amplifier U1. The third capacitor C3 is connected across the input positive terminal and the input negative terminal of the first operational amplifier U1.

[0035] The frequency-voltage conversion circuit 20 includes a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. One end of the first capacitor C1 is connected to the output port of the internal resistance Ri of the oxygen sensor, and the other end is respectively connected The first resistor R1, the second resistor R2; the first capacitor C1 is connected to the output terminal of the first operational amplifier U1 through the first resistor R1; one end of the second capacitor C2 is connected to the second resistor R2, and the other end is grounded .

[0036] The feedback loop 30 includes a third resistor R3, a ninth resistor R9, and a second operational amplifier U2. The positive input terminal of the second operational amplifier U2 is sequentially connected to the third resistor R3 and the second capacitor C2, and passes through the third resistor. R3, the second capacitor C2 is grounded, the input negative terminal of the second operational amplifier U2 is connected to its output terminal, the input negative terminal of the second operational amplifier U2 is connected to the ninth resistor R9, and the second operational amplifier U2 The output terminal is connected with the ninth resistor R9.

[0037] The foregoing detection circuit for the internal resistance of an oxygen sensor based on high-frequency injection further includes an eighth resistor R8, one end of the eighth resistor is connected to the power supply module VDD, and the other end of the eighth resistor R8 is connected to The seventh resistor R7 is connected to the high-frequency signal input port; one end of the fourth resistor R4 is connected to the power supply module VDD, and the other end is connected to the negative input terminal of the first operational amplifier U1.

[0038] The present invention provides a detection circuit for the internal resistance of an oxygen sensor based on high-frequency injection. A high-frequency signal is input from the injection signal port. The high-frequency signal passes through the first operational amplifier U1, the fourth resistor R4, the fifth resistor R5, and the A shaping circuit composed of six resistors R6, seventh resistor R7, third capacitor C3, fourth capacitor C4 and Zener Z1 performs waveform shaping. This signal passes through the oxygen sensor internal resistance Ri, the first resistor R1, and the second The resistor R2, the first capacitor C1 and the second capacitor C2 form a frequency-to-volt conversion circuit to generate a voltage signal. The amplitude of the voltage signal is related to the value of the internal resistance Ri of the oxygen sensor. By sampling the amplitude of the voltage, you can get The value of the internal resistance Ri of the oxygen sensor.

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Classification and recommendation of technical efficacy words

Real-time detection

High frequency injection-based oxygen sensor internal resistor detection circuit

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

PUM

Description & Claims & Application Information

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