Heater Power Control Using State Models to Reduce Thermal Stress
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Solution Overview
Problem
Heaters with resistive heating elements experience uneven heating due to manufacturing differences and position relative to heat sinks, leading to thermal stress and potential ceramic substrate cracks.
Innovation Solution
A control system that measures electrical characteristics and reference temperatures to adjust power distribution dynamically, using state model controls and correlation data to minimize thermal stress and ensure uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same power is applied to all resistive heating elements during heater startup, then the heater structure is simple and easy to control, but uneven heating occurs due to manufacturing differences and position relative to heat sinks, causing thermal stress and potential ceramic substrate cracks
Solution Approach 1:
The patent applies local quality by assigning different ramp rates to different heating zones based on their specific thermal characteristics. Each heating zone is monitored individually with temperature sensors, and the control system adjusts the power ramp rate locally for each zone rather than applying a uniform ramp rate to all zones. This resolves the contradiction by improving reliability through customized local control while managing complexity through a structured zoned approach.
Solution Approach 2:
The patent implements dynamics by making the power ramp rate adjustable and adaptive for each heating zone. The control system dynamically modifies the ramp rate based on real-time temperature feedback from sensors in each zone, allowing the system to respond to actual thermal conditions rather than following a fixed uniform ramp schedule. This dynamic adaptation improves reliability while the automated feedback control manages system complexity.
2Stability of the object's composition
If different ramp rates are applied to different heating zones to compensate for manufacturing variations, then heating uniformity improves and thermal stress reduces, but the control system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the heater into multiple independent heating zones, each with its own temperature sensor and control parameters. This allows each zone to be controlled independently with customized ramp rates based on its specific thermal characteristics and position relative to heat sinks. The segmentation resolves the contradiction by improving temperature uniformity through localized control while managing complexity through a modular zoned structure.
Solution Approach 2:
The patent implements feedback by using temperature sensors in each heating zone to monitor actual temperature and feed this information back to the control system. The control system uses this feedback to dynamically adjust the power ramp rate for each zone, ensuring temperature uniformity across all zones. The feedback mechanism improves stability while the automated closed-loop control manages system complexity.
3Reliability
If real-time temperature monitoring and dynamic power adjustment are implemented for each heating zone, then thermal stress and substrate cracks are prevented, but the system complexity and cost increase
Solution Approach 1:
The patent applies local quality by implementing individual temperature monitoring and control for each heating zone rather than uniform control. Temperature sensors are placed in critical zones to monitor local thermal conditions, and the control system adjusts power delivery locally to prevent thermal stress and substrate cracks. This localized approach improves substrate integrity while managing complexity by focusing monitoring and control resources where they are most needed.
Solution Approach 2:
The patent implements feedback through temperature sensors that continuously monitor heating zone temperatures and feed this information back to the control system. The control system uses this real-time feedback to dynamically adjust power ramp rates and prevent conditions that would cause thermal stress or substrate damage. The automated feedback control improves reliability while reducing the need for complex manual intervention.
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
Reduces thermal stress and prevents substrate cracks by optimizing power delivery based on real-time electrical and thermal feedback, ensuring consistent temperature across heating zones.
Implementation Method 1
a heating plate that has a ceramic substrate and a plurality of resistive heating elements embedded in the ceramic substrate
Data Source
AI summary
A method includes selecting a state model control, as an operational state of the heater, from among a plurality of state model controls, measuring an electrical characteristic of the heater, where the electrical characteristic includes at least one of an electric current and a voltage, and controlling power to the heater based on the selected operational state and based on the measured electrical characteristic.