System and method for controlling power to a heater
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Solution Overview
Problem
In thermal systems with resistive heating elements, non-uniform heating due to manufacturing differences and position relative to heat sinks leads to thermal stress and potential cracking in ceramic substrates, as the same power is applied to all elements during startup, causing uneven heating and expansion.
Innovation Solution
A control system comprising a power converter, sensor circuit, and controller that adjusts power supply to heating elements based on measured electrical characteristics and temperature data, using state model controls to manage power distribution and reduce thermal stress by dynamically adjusting power to each zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the same power is applied to all resistive heating elements during heater startup, then the heating process is simple and fast, but thermal stress and cracking occur in the ceramic substrate due to non-uniform heating
Solution Approach 1:
The patent applies different power levels to different heating zones based on their individual characteristics. The controller adjusts the power supplied to each heating element independently, creating local quality variations that compensate for non-uniform heating tendencies. This resolves the contradiction by maintaining fast heating overall while preventing thermal stress in specific vulnerable zones through localized power adjustment.
Solution Approach 2:
The patent implements dynamic power adjustment during the heating process. The controller continuously monitors temperature and modifies power distribution in real-time, transitioning from static equal power distribution to dynamic adaptive power distribution. This dynamic approach allows the system to maintain high heating efficiency while preventing thermal stress as conditions change during operation.
2Reliability
If different power levels are applied to different heating zones, then thermal stress and cracking are reduced, but the control system complexity increases
Solution Approach 1:
The patent employs feedback control where temperature sensors monitor each heating zone and the controller adjusts power distribution based on this feedback. This feedback mechanism automates the complex decision-making process, reducing the need for manual intervention while maintaining reliable thermal stress prevention. The feedback loop handles the complexity internally, presenting a simplified interface to the user.
Solution Approach 2:
The control system performs self-adjustment based on temperature measurements and pre-programmed parameters. Once the system is initialized with heating zone characteristics, it autonomously manages power distribution without requiring continuous user input or complex external control. The system serves itself by automatically compensating for thermal variations and preventing stress conditions.
3Ease of operation
If the same ramp rate is used for all heating elements, then the control process is simple, but temperature differences between zones cause thermal stress
Solution Approach 1:
The patent divides the heating control into separate segments or zones, each with its own power adjustment capability. Instead of applying a single ramp rate to the entire heater, the system segments the control into multiple independent heating zones that can be managed separately. This segmentation allows simple individual zone control while preventing thermal stress through coordinated zone management.
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
The control system effectively reduces thermal stress and prevents cracking by ensuring uniform heating across zones, maintaining optimal temperature control and extending the lifespan of the heating elements.
Implementation Method 1
a heating plate that has a ceramic substrate and a plurality of resistive heating elements embedded in the ceramic substrate
Implementation Method 2
the position of the heating zones relative to heat sinks, and differences in the characteristics of the heating zones
Data Source
AI summary
A control system for controlling a heater includes a power converter, a sensor circuit, and a controller. The power converter supplies an adjustable power to the heater, and the sensor circuit is configured to measure an electrical characteristic of the heater. The controller is coupled to the power converter to control the power to the heater, and is configured to select a state model control, as an operation state of the heater, from among a plurality of defined state model controls. The controller controls the power supplied to the heater based on the operation state of the heater and on the electrical characteristics of the heater.