Oxygen Sensor Digital Compensator Balancing Current
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Solution Overview
Problem
Diagnostic routines in oxygen sensors disrupt the closed-loop control, causing the sensor to deviate from its desired operating point due to the opening of the pump control loop and open circuit diagnostics, leading to errors and a disturbance in the control loop upon resumption of normal operation.
Innovation Solution
A compensator circuit with a digital compensator is used to pump a balancing current into or out of the pump cell for a balancing time interval, dependent on the current pumped prior to the disruption, to quickly restore the sensor's equilibrium after diagnostic procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diagnostic routines are implemented to test sensor connections, then reliability of sensor operation is improved, but the closed-loop control is disrupted causing measurement precision to deteriorate
Solution Approach 1:
The patent applies preliminary action by performing charge compensation at the beginning of diagnostic routines. The system calculates the charge removed during upcoming diagnostic events and compensates for it in advance by adjusting pump cell current, ensuring the sensor returns to its proper operating point quickly after diagnostics complete.
Solution Approach 2:
The patent implements feedback by continuously monitoring the reference cell voltage and pump current, and using this information to dynamically adjust the compensation strategy. The control loop measures the actual charge removed during diagnostics and applies corrective pump current to restore the sensor to its desired operating state.
2Ease of operation
If the pump control loop is opened during diagnostic periods, then ease of operation for diagnostics is improved, but the sensor deviates from its desired operating point causing productivity to deteriorate
Solution Approach 1:
The system performs preliminary charge compensation before diagnostic routines begin, calculating the expected charge removal and applying compensating pump current in advance. This minimizes the time the sensor spends away from its operating point and reduces the recovery time needed after diagnostics.
Solution Approach 2:
The patent implements a focused compensation strategy that concentrates the necessary charge restoration into a brief period immediately following diagnostics, rather than allowing a prolonged recovery phase. This rushes through the transition back to normal operation, minimizing productivity loss.
3Reliability
If open circuit diagnostic mechanism is implemented, then reliability of connection testing is improved, but charge is pulled out of the cells causing measurement precision to deteriorate
Solution Approach 1:
The system calculates the charge that will be removed during open circuit diagnostics based on the expected diagnostic duration and circuit characteristics, and applies compensating pump current before the diagnostics begin. This preliminary compensation ensures the sensor starts from a known state and recovers quickly.
Solution Approach 2:
The patent introduces an intermediary compensation mechanism that acts as a buffer between the diagnostic routine and the sensor cells. The compensator circuitry mediates the charge transfer, applying corrective current through the pump cell to offset the charge removal caused by the open circuit diagnostic mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes the disruption and error accumulation during diagnostics, allowing the sensor to return to its operating point quickly, reducing disturbances in the control loop and maintaining accurate oxygen level measurements.
Implementation Method 1
a pump cell, adapted to pump oxygen into or out of the measurement chamber by means of an electric current
Implementation Method 2
A lambda sensor is based on a solid-state electrochemical fuel cell. Its electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere
Data Source
AI summary
An oxygen sensor is in a system including compensator circuitry connected to the oxygen sensor. The oxygen sensor includes a pump cell and the compensator circuitry includes a feedback control loop which includes a digital compensator which determines and outputs a compensation current to the pump cell or adjusts a pump cell voltage. A method of controlling the oxygen sensor includes, subsequent to a period of time when the feedback control loop is disrupted, pumping a balancing current into or out the pump cell for a balancing time interval, the balancing current and/or the balancing time interval is dependent on a current pumped into or out of the pump cell prior to the feedback control loop being disrupted.