Induction Cooktop Control via Zero-Crossing Signal Sampling
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Solution Overview
Problem
Conventional induction cooking appliances face inefficiencies due to non-uniform heating and inaccurate temperature control, particularly because current transformers yield inconsistent outputs and have large, expensive packages.
Innovation Solution
A method and system for controlling an induction cooking appliance by supplying a high-frequency signal, detecting the power signal frequency, initiating a timer at zero magnitude, sampling a signal through a shunt resistor, and calculating status factors to accurately control the cooking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current transformer is used for frequency detection and control, then the induction cooking appliance can control the cooking temperature, but the output becomes inconsistent and inaccurate over a frequency range due to transformer loss principles
Solution Approach 1:
The patent extracts the frequency detection function from the current transformer and implements it separately using a zero-crossing detector and timer circuit. This separation allows the frequency detection to be performed independently without the losses and inaccuracies inherent in transformer-based current sensing, thereby improving both measurement precision and output consistency.
Solution Approach 2:
The patent replaces the electromagnetic transformer-based detection system with an electronic timing-based system. By using zero-crossing detection to trigger a timer that counts cycles of the control signal, the system substitutes mechanical/electromagnetic transformation with electronic timing and counting, eliminating transformer losses and improving reliability.
2Loss of information
If a current transformer is used for control signal sampling, then the induction cooking appliance can monitor the cooking process, but the package size and footprint increase
Solution Approach 1:
The patent extracts the control signal sampling function from the current transformer package and implements it using discrete electronic components (zero-crossing detector, timer, and counter). This extraction eliminates the need for a large transformer package while maintaining the ability to monitor and feedback control signal information.
Solution Approach 2:
The patent changes the approach from electromagnetic transformation to electronic timing parameters. By using time-based measurement (counting control signal cycles within a predetermined time interval) rather than current transformation, the system achieves the same monitoring function with much smaller component footprint.
3Power
If a current transformer is used for frequency detection, then the induction cooking appliance can regulate power output, but the system cost increases
Solution Approach 1:
The patent replaces the expensive current transformer with inexpensive electronic components such as zero-crossing detectors, timers, and digital counters. These cheaper components perform the same frequency detection and power regulation functions, significantly reducing system cost while maintaining power regulation capability.
Solution Approach 2:
The patent substitutes the costly electromagnetic transformer system with a digital electronic timing system. By using microcontroller-based or discrete electronic timing circuits to count control signal cycles, the system achieves power regulation at a fraction of the cost of transformer-based solutions.
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 approach enables precise control of induction cooking, improving temperature uniformity and reducing costs by using a shunt resistor for feedback sampling, leading to more efficient and reliable cooking performance.
Implementation Method 1
A power supply provides a signal having a frequency to the induction coil. When the coil is activated a magnetic field is produced which induces a current on the bottom surface of the cookware. The induced current on the bottom surface then induces even smaller currents (Eddy currents) within the cookware thereby providing heat throughout the cookware.
Implementation Method 2
The induced current on the bottom surface then induces even smaller currents (Eddy currents) within the cookware thereby providing heat throughout the cookware.
Implementation Method 3
sampling a signal through a shunt resistor after the time interval, and calculating at least one of a plurality of status factors based on the shunt resistor signal sample.
Data Source
AI summary
A system and method of controlling an induction cooking appliance based on a feedback signal. A feedback signal sampling time interval may be triggered when a power control signal has a magnitude of zero. The feedback signal sample may be used to calculate a status factor and the appliance may be controlled based on the calculated status factor.