Microwave Sous Vide IR Sensor Calibration for Accurate Temperature Control
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Solution Overview
Problem
Microwave appliances face challenges in accurately detecting temperature due to microwave radiation distorting sensor readings and uneven heating, particularly affecting delicate cooking operations like sous vide.
Innovation Solution
A microwave appliance with a temperature sensor and controller that uses calibration methods to measure initial and chamber temperatures, adjusting power levels based on conversion models to maintain accurate cooking temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If microwave radiation is used to heat food in the cooking chamber, then heating efficiency is improved, but temperature measurement accuracy deteriorates due to radiation distortion
Solution Approach 1:
The system performs preliminary calibration before actual cooking by measuring temperatures at multiple power levels and establishing conversion models. This preliminary action creates a reference framework that compensates for radiation distortion during subsequent temperature measurements, allowing accurate temperature control despite microwave radiation interference
Solution Approach 2:
The system changes measurement parameters by taking temperature readings at multiple different power levels (not just a single operating point) and using these varied parameters to build conversion models. This multi-parameter approach enables the system to account for non-linear relationships between power level and temperature, improving measurement accuracy under varying microwave radiation conditions
2Productivity
If the magnetron operates at high power to reduce cooking time, then productivity is improved, but temperature control precision deteriorates due to uneven heating and hot spots
Solution Approach 1:
The system uses periodic temperature measurements at multiple power levels during calibration and operation to capture the dynamic thermal behavior of the cooking chamber. By periodically sampling temperatures under different heating conditions, the system builds a comprehensive model that accounts for uneven heating patterns and hot spots, enabling precise temperature control even during high-power cooking
Solution Approach 2:
The system implements feedback control by continuously monitoring temperature measurements and comparing them against target temperatures using the established conversion models. The controller adjusts power levels based on this feedback to compensate for uneven heating and hot spots, maintaining precise temperature control throughout the cooking process while preserving cooking speed
3Loss of energy
If the cooking chamber is made reflective to contain microwave energy, then energy efficiency is improved, but temperature measurement accuracy deteriorates due to reflected infrared radiation
Solution Approach 1:
The system introduces conversion models as an intermediary layer between the raw temperature sensor readings and the actual chamber temperature. These models, built through calibration at multiple power levels, act as a mediator that translates distorted readings (affected by reflected infrared radiation from reflective surfaces) into accurate temperature measurements, allowing the reflective chamber to maintain energy efficiency while enabling precise temperature control
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
Achieves precise temperature control during preheating and cooking, ensuring consistent and accurate sous vide cooking results.
Implementation Method 1
The magnetron may be operable to generate microwave radiation to provide heat to the cooking chamber
Implementation Method 2
The cooking chamber may be reflective and may reflect infrared radiation within the cooking chamber in addition to infrared radiation being emitted into the cooking chamber by the magnetron
Data Source
AI summary
A microwave appliance includes a cabinet defining a cooking chamber, a magnetron, a temperature sensor directed toward the cooking chamber, and a controller. The controller is configured to measure a raw temperature of the cooking chamber, determine a calibrated temperature from the raw temperature and a conversion model, determine a preheat power level for the magnetron, and operate the magnetron at the preheat power level. The controller is further configured to determine a calibrated chamber temperature using a chamber temperature and a preheat conversion model and determine the calibrated chamber temperature has reached a target temperature. The controller is further configured to monitor a calibrated cooking temperature, based on a cooking temperature and a cooking conversion model, and operate the magnetron to a cooking power level to maintain the calibrated cooking temperature at the target temperature. A method of operating a microwave appliance with a temperature sensor is also disclosed.