Push-Pull Induction Heating Circuit for Single-Layer Bowls
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Solution Overview
Problem
Existing induction heating circuits for cookers, such as rice cookers, face challenges in manufacturing cost and efficiency due to the requirement for double-layer metal bowls and complex coil configurations, particularly with the Class-E converter type circuit, which is less efficient and more costly than the push-pull converter type but often necessitates a double-layer bowl for proper operation.
Innovation Solution
Adopting a push-pull converter type circuit with new winding methods for the heating coils, allowing the use of single-layer metal bowls and enabling efficient heating with a transformer configuration, where the first and second heating coils define a circle-like shape with substantial similarity in shape and size to maintain equal inductance, reducing manufacturing costs and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Class-E converter type circuit is used, then manufacturing cost is reduced, but power efficiency deteriorates and the circuit cannot operate properly with low resistance bowls
Solution Approach 1:
The patent changes the circuit topology from Class-E to push-pull converter type, fundamentally altering the operating parameters and switching mechanism to achieve both cost-effectiveness and high efficiency with single-layer bowls
Solution Approach 2:
The heating coil is segmented into two separate coils with identical inductance values, each connected to one side of the push-pull converter, enabling balanced operation and improved power efficiency
2Loss of energy
If push-pull converter type circuit is used, then power efficiency is improved, but device complexity increases due to requiring two heating coils with equal inductance
Solution Approach 1:
While the circuit requires symmetry in inductance values, the winding method allows asymmetric physical placement of coils, providing design flexibility while maintaining electrical symmetry for optimal push-pull operation
Solution Approach 2:
The patent specifies precise inductance matching (substantially equal inductance values) as a key parameter requirement for the two coils, enabling the push-pull converter to operate efficiently while managing the complexity through standardized design criteria
3Reliability
If double layer metal bowl is used, then Class-E converter operation is enabled, but manufacturing cost increases
Solution Approach 1:
The patent changes the bowl structure from double-layer to single-layer construction, fundamentally altering the load characteristics while compensating through push-pull converter topology to maintain reliable operation
Solution Approach 2:
The patent replaces the expensive double-layer bowl structure with a simpler, cheaper single-layer aluminum bowl, reducing material costs while ensuring adequate service life through proper thermal management
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
The push-pull converter type circuit reduces manufacturing costs by enabling the use of single-layer metal bowls and enhances power efficiency, achieving better performance compared to Class-E converter type circuits, with improved power efficiency and reduced switching and conduction losses.
Implementation Method 1
induction heating circuit for cooker, e.g., a rice cooker
Implementation Method 2
The push-pull converter type circuit enables the use of a single layer bowl rather than a traditional double layer bowl
Implementation Method 3
a first heating coil provided between first and second nodes and being configured to heat the conductive bowl; a second heating coil provided between the second node and a third node and being configured to heat the conductive bowl
Data Source
AI summary
A heating circuit for heating a conductive bowl includes a voltage source; a first heating coil provided between first and second nodes and being configured to heat the conductive bowl; a second heating coil provided between the second node and a third node and being configured to heat the conductive bowl; first capacitor and first switch provided in parallel between the first node and a fourth node; and second capacitor and second switch provided in parallel between the third node and the fourth node. The first and second heating coils define a circle-like shape having a center. The first and second heating coils are configured to be aligned to each other if one of the first and second heating coils is moved with respect to a line extending through the center of the circle-like shape.