Load Resistance Controller Calibration for Offset Compensation
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Solution Overview
Problem
Existing controllers face challenges in obtaining accurate resistance measurements due to offset errors and gain errors, particularly at lower power levels, which affect temperature determination in loads such as resistive heating elements.
Innovation Solution
A method and system for enhancing resistance measurements by determining an offset correction value based on resistance differences, using voltage and current measurements, and applying correction values to improve accuracy, including voltage and current offset corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage and current measurements are used to calculate resistance for temperature determination, then temperature control capability is improved, but measurement accuracy deteriorates due to offset errors and gain errors of the controller
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements at multiple known temperature points before actual operation. The controller stores calibration data obtained from resistance measurements at predetermined temperatures, which are then used to correct subsequent resistance measurements. This preliminary calibration establishes a reference framework that compensates for controller errors during normal operation.
Solution Approach 2:
The patent utilizes parameter changes by measuring resistance at multiple different temperature setpoints during calibration. By varying the temperature parameter and recording the corresponding resistance values, the system creates a calibration curve that accounts for non-linear relationships and controller drift. This multi-point approach transforms the single-parameter measurement into a multi-parameter calibration process.
2Measurement precision
If calibration is performed at multiple temperature setpoints to improve accuracy, then measurement precision is improved, but calibration time and complexity increase
Solution Approach 1:
The patent applies partial action by selecting a limited number of critical temperature setpoints for calibration rather than attempting to calibrate at every possible temperature. The system identifies key calibration points that provide sufficient accuracy for the application, performing measurements only at these essential points. This reduces calibration time while maintaining adequate measurement precision across the full temperature range.
3Measurement precision
If offset correction values are applied to compensate for controller errors, then measurement accuracy is improved, but device complexity increases due to additional correction calculations
Solution Approach 1:
The patent implements feedback by using the calibrated relationship between temperature and resistance to continuously correct measurements. The controller compares measured resistance values against the calibration data stored in memory, automatically applying correction factors based on the deviation from expected values. This closed-loop feedback mechanism maintains accuracy without requiring complex real-time calculations.
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
Improves the accuracy of resistance and temperature measurements by compensating for offset errors, ensuring precise control of loads like resistive heating elements.
Implementation Method 1
the controller calculates resistance based on voltage and/or current measurements
Implementation Method 2
a heater having one or more resistive heating elements and a controller for controlling power to the heater to generate heat
Data Source
AI summary
A method for enhancing resistance measurements of a load includes determining a resistance difference based on an average resistance value associated with the load and a nominal resistance value associated with the load, and measuring a resistance of the load based on an offset correction value of a controller and one or more electrical characteristics of the load, where the offset correction value is based on the resistance difference, and the offset correction value includes a voltage offset correction value, a current offset correction value, or a combination thereof.