Sensor control apparatus, sensor control system, and sensor control method

A sensor control method which is performed in a sensor control apparatus for controlling a gas sensor including a first measurement chamber into which an object gas is introduced, a first oxygen pump cell having a first solid electrolyte layer and paired first electrodes provided on an inside and outside, respectively, of the first measurement chamber, a second measurement chamber in communication with the first measurement chamber, and a second oxygen pump cell having a second solid electrolyte layer and paired second electrodes provided on an inside and outside, respectively, of the second measurement chamber, the sensor control method comprising:

• a drive control step of performing drive control for adjusting an oxygen concentration of the object gas introduced into the first measurement chamber by supplying electric current to the first oxygen pump cell and for applying an operating voltage to the second oxygen pump cell;
• a preliminary control step of performing, before start of the drive control, preliminary control which supplies a constant current to the second oxygen pump cell over a constant period of time, to thereby control to a constant level an amount of oxygen pumped out from the second measurement chamber to the outside of the second measurement chamber;
• a calculation step of calculating a concentration correspondence value which represents a concentration of a specific gas contained in the object gas, on the basis of the magnitude of current flowing through the second oxygen pump cell to which the operating voltage is applied after the start of the drive control;
• a determination step of determining a timing for applying correction data, such that a pattern of a time course change exhibited by the concentration correspondence value after the start of the drive control approximately coincides with a pattern of a time course change represented by the correction data, the correction data being pattern data which is stored in storage means of the sensor control apparatus commonly among a plurality of the gas sensors and which represents a pattern of a time course change in the concentration correspondence value after the drive control is started after the preliminary control which has been set in advance is executed, which pattern data is obtained under a combination where both the preliminary control and the drive control are performed in the presence of the reference gas;
• and
• a correction step of correcting the concentration correspondence value by applying the correction data to the concentration correspondence value on the basis of the timing determined by the determination step.