Induction Heating Device Location Detection via Phase Difference
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Solution Overview
Problem
Conventional induction cooking stoves face challenges in accurately detecting the location of a foodstuff container due to high-frequency current calculations, leading to increased costs and errors, and a risk of device burnout from improper positioning.
Innovation Solution
A heating device with an induction coil, inverter circuit, first current-detecting circuit, signal processing circuit, and controlling unit that determines the container's location by analyzing the duration or phase difference between control and current phase signals, allowing for adjustments in the inverter circuit operation to prevent burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional method using MCU to calculate RMS values is used, then the location detection function is achieved, but the calculating amount and speed requirements increase and fabricating cost increases
Solution Approach 1:
The patent replaces the conventional method of calculating RMS values through complex mathematical computations with a simplified approach using rectified voltage signals. Instead of computing RMS of high-frequency currents, the system uses the relationship between rectified voltage and current to derive location information, substituting complex mechanical calculation with a more straightforward electrical measurement approach.
Solution Approach 2:
The patent changes the measurement parameter from RMS current values to rectified voltage values. By measuring the rectified voltage across the induction coil and using its relationship with the driving voltage, the system achieves location detection without needing to compute RMS values, thereby reducing computational complexity while maintaining detection accuracy.
2Measurement precision
If current transformer or sense resistor is used to reduce circuit magnitudes, then the current magnitude can be measured, but the impedance matching tolerances and noise interference cause large errors
Solution Approach 1:
The patent introduces the rectified voltage signal as an intermediary measurement. Instead of directly measuring current through transformers or resistors that are susceptible to noise and tolerance errors, the system measures the rectified voltage across the induction coil, which serves as a reliable intermediary that correlates with current magnitude without the same susceptibility to interference.
Solution Approach 2:
The patent substitutes the physical current sensing components (current transformers or sense resistors) with a voltage-based measurement system. By measuring rectified voltage and using its relationship with the driving voltage, the system eliminates the need for current-sensing hardware that introduces tolerance errors and noise susceptibility.
3Temperature
If the foodstuff container is largely deviated from the induction coil, then the heat quantity becomes very low, but the reactive power and current magnitude increase causing possible burnout
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the rectified voltage signal and comparing it with the driving voltage signal. When the foodstuff container is deviated or absent, the rectified voltage changes, providing feedback to the control system. This feedback allows the system to detect improper positioning and adjust or shut off power to prevent burnout, while maintaining high heating efficiency when properly positioned.
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 enables accurate detection of the foodstuff container's location with reduced computational complexity and error, while preventing device burnout by adjusting the inverter circuit's operation based on signal differences, thus enhancing the device's reliability and cost-effectiveness.
Implementation Method 1
When a current flows through the induction coil of the induction cooking stove, electromagnetic induction is performed to produce eddy current, thereby heating a foodstuff container
Implementation Method 2
electromagnetic induction is performed to produce eddy current, thereby heating a foodstuff container
Data Source
AI summary
A heating device having a function of detecting a location of a foodstuff container is provided. The heating device includes an induction coil, an inverter circuit, a first current-detecting circuit, a signal processing circuit and a controlling unit. The first current-detecting circuit is used for detecting a first current flowing through the induction coil and generating a first current-detecting signal. The signal processing circuit is used for generating a current phase signal according to the first current-detecting signal. The controlling unit is used for generating at least a first control signal according to a cooking option. According to a duration difference or a phase difference between the first control signal and the current phase signal, the controlling unit determines an area of the foodstuff container overlying the induction coil with respect to an area of the induction coil or a location of the foodstuff container relative to the induction coil.