Power supply control system for heater used in gas sensor
AssigneeDenso Corporation
InventorsSatoshi Hada, Eiichi Kurokawa
Life of this patent
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Abstract
A heater power supply control system is provided for controlling the temperature of a heater used to heat a solid electrolyte-made sensor element of a gas concentration sensor up to a desired activation temperature. The heater power supply control system measures a resistance value of the sensor element and controls an electric power supply to the heater using a PI control function. The heater power supply control system works to limit the value of an integral term of the PI control function in the course of activation of the sensor element, thereby avoiding overshoot of the resistance value of the sensor element, which avoids thermal damage of the sensor element.
Claims18
A heater control apparatus comprising:
- a control circuit working to control a power supply to a heater used to heat a solid electrolyte-made sensor element of a gas concentration sensor up to a temperature at which the sensor element is activated to provide a desired gas concentration output;
- a sensor element resistance determining circuit working to determine a resistance value of the sensor element of the gas concentration sensor;
- and
- a heater control variable determining circuit determining a heater control variable for controlling the power supply to the heater in said control circuit based on a value of an integral term in a control function which is determined as a function of a difference between the resistance value determined by said sensor element resistance determining circuit and a target value, said heater control variable determining circuit putting a limitation on increasing of the value of the integral term until the resistance value of the sensor element reaches a preselected value in the course of activation of the sensor element.
A heater control apparatus comprising:
- a control circuit working to control a power supply to a heater used to heat a solid electrolyte-made sensor element of a gas concentration sensor up to a temperature at which the sensor element is activated to provide a desired gas concentration output;
- a sensor element resistance determining circuit working to determine a resistance value of the sensor element of the gas concentration sensor;
- and
- a heater control variable determining circuit determining a heater control variable for controlling the power supply to the heater in said control circuit based on values of an integral and a proportional term of a control function used in proportional plug integral control which are each determined as a function of a difference between the resistance value determined by said sensor element resistance determining circuit and a target value, said heater control variable determining circuit increasing at least one of gains of the integral and proportional terms when the resistance value of the sensor element is shifted to a side on which temperature of the sensor element is increased out of a controlled range defined across the target value.
A heater control apparatus comprising:
- a control circuit working to control a power supply to a heater used to heat a solid electrolyte-made sensor element of a gas concentration sensor up to a temperature at which the sensor element is activated to provide a desired gas concentration output;
- a sensor element resistance determining circuit working to determine a resistance value of the sensor element of the gas concentration sensor;
- and
- a heater control variable determining circuit determining a heater control variable for controlling the power supply to the heater in said control circuit as a function of a difference between the resistance value determined by said sensor element resistance determining circuit and a target value so as to bring the difference into agreement with the target value, said heater control variable determining circuit switching the target value between an initial value and a final value lower than the initial value during activation of the sensor element.
Dependencies are inferred from the claim text.