Heater Control via Current Slope for Sensorless Temperature Regulation
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Solution Overview
Problem
Heater control systems without temperature sensors face challenges in accurately controlling temperature, especially in systems with high resistance tolerance ranges, leading to inefficiencies and increased complexity and cost.
Innovation Solution
A heater control system that uses a current sensor, slope calculator, and mode selector to estimate surface temperature by monitoring the slope of current supplied to the heater, eliminating the need for temperature sensors and reference resistances, and adjusts the duty cycle of the heater driver based on the slope to maintain accurate temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to control heater temperature, then temperature control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature sensing function from a dedicated temperature sensor and implements it through electrical measurement of heater element properties. By measuring resistance or current slope of the heater element itself, the system obtains temperature information without adding separate sensing components, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The heater element serves dual functions: heating and temperature sensing. The same component that generates heat also provides the electrical properties (resistance, current slope) used for temperature measurement. This multi-functionality eliminates the need for separate temperature sensors, reducing device complexity while maintaining control accuracy
2Measurement precision
If reference resistance is used to determine heater wire temperature in systems with high resistance tolerance, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The system uses the heater element's own electrical characteristics (resistance or current slope) to determine its temperature. This self-service approach eliminates the need for separate reference resistance components or complex calibration systems, achieving accurate temperature measurement without increasing device complexity
Solution Approach 2:
The patent replaces physical reference resistance components with electrical measurement methods. By measuring the current slope or resistance of the heater element itself, the system substitutes complex physical reference systems with simpler electrical measurements, reducing device complexity while maintaining accuracy
3Device complexity
If current slope is used to estimate surface temperature without temperature sensors, then device complexity and cost are reduced, but temperature control accuracy may deteriorate
Solution Approach 1:
The system continuously monitors the current slope or resistance of the heater element and uses this feedback to adjust the heating power. This closed-loop control ensures accurate temperature regulation despite the simplified sensing method, resolving the contradiction between reduced device complexity and maintained control accuracy
Solution Approach 2:
The patent changes the measurement parameter from direct temperature sensing to electrical parameter measurement (current slope or resistance). By monitoring how these electrical parameters change with temperature, the system achieves accurate temperature control through indirect measurement, reducing device complexity while maintaining precision
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 solution allows for accurate temperature control of heated surfaces without temperature sensors, reducing costs and increasing reliability, while maintaining comfort by adjusting the heating rate to prevent overheating.
Implementation Method 1
A current sensor is arranged between the heater driver and the heater to sense current supplied to the heater
Implementation Method 2
Heaters are used to heat some of the exposed interior surfaces of the vehicle that are in contact with the occupants of the vehicle
Data Source
AI summary
A heater control system includes a heater driver, a current sensor, a slope calculator, and a mode selector. The heater driver is configured to control current to a heater. The current sensor is configured to sense current supplied to the heater. The slope calculator is configured to calculate a slope of the current supplied to the heater. The mode selector is configured to adjust current supplied to the heater by the heated driver based on the slope of the current.