Induction Trolley Heating Control for Partial Fill Levels
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Solution Overview
Problem
Existing devices for inductively heating crockery elements in a box-shaped structure often result in excessive heating when the trolley is partially filled, as the electromagnetic behavior changes, leading to uneven heating without the use of a core temperature sensor.
Innovation Solution
A device that stores calibration values for current supply to the induction coils in a computing module, allowing for measurement of current intensity and adjustment of the duty cycle or power correction factor to ensure consistent heating regardless of the number of crockery items, using a series and parallel electrical connection of induction coils, and a piecewise linear interpolation of temperature and current measurements to determine a reduction factor for the duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the box-shaped trolley is partially filled with crockery items, then the electromagnetic behavior changes, but this leads to excessive heating of the food
Solution Approach 1:
The patent implements dynamic adjustment of the duty cycle based on the measured current strength. The control module continuously monitors the current and adjusts the duty cycle in real-time to compensate for changes in electromagnetic behavior caused by different fill levels, ensuring consistent heating performance whether the trolley is fully or partially filled.
Solution Approach 2:
The patent employs a feedback mechanism where the measuring module continuously monitors the current strength supplied to the induction coils, and this measured value is fed back to the control module. The control module uses this feedback information to dynamically adjust the duty cycle, creating a closed-loop control system that maintains optimal heating conditions regardless of fill level variations.
2Measurement precision
If calibration values are stored and duty cycle is adjusted based on measured current strength, then precise temperature control is achieved, but device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically determining correction factors based on measured current strengths at different fill levels. The control module stores these calibration values and uses them to automatically adjust the duty cycle without requiring manual intervention or complex external calibration equipment, thereby achieving precise control while limiting complexity growth.
Solution Approach 2:
The patent changes the operational parameters of the heating system by adjusting the duty cycle based on measured current strength and stored calibration values. This parameter adjustment approach allows precise temperature control to be achieved through software-based modifications rather than hardware complexity, maintaining system simplicity while improving measurement 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
Enables precise heating of food to a desired temperature without overheating, regardless of the number of crockery elements, by adjusting the current intensity and duty cycle based on measured current strength, ensuring consistent performance across varying fill levels.
Implementation Method 1
An electromagnetic effect between the induction coils and the conductive layer of the crockery elements results in a transfer of energy between the induction coils and the conductive layers of the crockery elements and thus the crockery elements and the food arranged in the crockery elements are heated
Implementation Method 2
Induction coils are attached to the bases, through which a current can flow by means of a generator. An electromagnetic effect between the induction coils and the conductive layer of the crockery elements results in a transfer of energy
Data Source
Figure 1
AI summary
A metallic housing (100) has multiple shelves (10- 12) having induction coils (20-22) connected in series to a waveform generator (4) and having conductive sheets (30-32) holding plates of food. A measuring system (1) determines the total value of the induction current and a computer (2) controls the output.