Induction Cooker Coil Control for Rapid Load Detection
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Solution Overview
Problem
Existing induction heating cookers with multiple coils require a long time to determine the load, especially in a no-load state, due to the need for calculating current ratios across different frequencies, which hinders rapid operation cessation.
Innovation Solution
The induction heating cooker employs a configuration where multiple heating coils are driven by a single driver circuit, allowing the controller to quickly determine the presence of a heating target by distinguishing between conduction and non-conduction states of the coils, thereby rapidly stopping the load determination operation when no target is present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple coils are driven by separate inverter circuits, then each coil can be controlled independently, but the device complexity increases and the load determination time becomes longer
Solution Approach 1:
The patent merges multiple inverter circuits into a single inverter circuit that can drive multiple coils. The controller selectively connects each coil to the inverter circuit through switching elements, enabling independent control of each coil while using a shared inverter circuit. This reduces device complexity while maintaining independent coil control capability.
Solution Approach 2:
The single inverter circuit is designed to serve multiple coils universally. By incorporating switching elements that can connect any coil to the inverter circuit, the system achieves multi-functionality where one inverter circuit can control multiple coils independently, eliminating the need for separate inverter circuits for each coil.
2Measurement precision
If current ratio calculation is performed at multiple frequencies, then load determination accuracy is improved, but the load determination time increases
Solution Approach 1:
The patent implements a two-stage load determination process. First, a preliminary load determination is performed using a single frequency to quickly identify whether a load is present. If a load is detected, then a more accurate multi-frequency current ratio calculation is performed. This partial action approach reduces the time when multi-frequency calculation would otherwise be unnecessarily performed in no-load conditions.
Solution Approach 2:
The system performs a preliminary load detection using a single frequency before initiating the more time-consuming multi-frequency current ratio calculation. This preliminary action allows the system to quickly eliminate no-load cases, ensuring that the accurate but time-consuming multi-frequency analysis is only performed when actually needed, thus reducing overall load determination time.
3Measurement precision
If load determination operation continues in no-load state, then measurement precision is maintained, but energy consumption increases
Solution Approach 1:
The patent implements periodic load determination rather than continuous operation. The controller periodically checks the load state using the inverter circuit and coils, and when no load is detected, the system transitions to a standby state where the coils are disconnected. This periodic action maintains measurement precision by regularly checking for loads while reducing energy consumption by idleing the system between checks.
Solution Approach 2:
The system extracts and removes the coils from the active circuit when no load is detected. By using switching elements to disconnect the coils from the inverter circuit in no-load conditions, the system eliminates unnecessary energy consumption while maintaining the ability to quickly detect loads when they are placed on the cooktop.
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 configuration enables rapid load determination cessation in a no-load state, improving operational efficiency and reducing unnecessary energy consumption by ensuring timely shutdown of the driver circuit.
Implementation Method 1
a driver circuit 50 that supplies a high-frequency current to each of the heating coils 110, 120
Implementation Method 2
a first heating unit 11 that induction-heats a heating target 5 placed thereon
Data Source
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AI summary
An induction heating cooker according to an embodiment of the present disclosure includes a driver circuit configured to supply a high-frequency current to each of a plurality of heating coils including an inner coil and an outer coil, a switcher unit configured to switch each of the plurality of heating coils into one of a conduction state and a non-conduction state, and a controller configured to determine whether a heating target is present above the inner coil while the inner coil is in the conduction state and the outer coil is in the non-conduction state, and when the controller determines that no heating target is present above the inner coil, the controller stopping an operation of the driver circuit.