Half-Bridge Power Switch Control for Induction Cooker Current Extinction
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Solution Overview
Problem
Conventional induction cooking appliances require simultaneous blocking of both power elements in a half-bridge circuit to extinguish the alternating current, which complicates the control process and may lead to unnecessary complexity and potential risks like short-circuits.
Innovation Solution
A method and device that control two power elements in a half-bridge by maintaining one element in an on state and the other in an off state using a single frequency control signal, allowing for the extinction of the alternating current without needing additional control signals, and ensuring safety by maintaining both elements in a blocked state post-extinction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both power elements are simultaneously blocked to extinguish the alternating current, then the current extinction is achieved, but the control process becomes complicated and additional control signals are required
Solution Approach 1:
The patent extracts the unnecessary requirement of simultaneously blocking both power elements. By maintaining only one power element in the on-state and the other in the off-state during current extinction, the solution removes the complexity of coordinated dual-blocking control while achieving reliable current extinction through the natural decay of inductive current when the circuit is opened at one point.
Solution Approach 2:
The control process is segmented into distinct phases: during normal operation both power elements alternate on/off to generate AC, and during extinction one power element is held on while the other is held off. This segmentation allows independent control of each power element state, simplifying the control logic from coordinated dual-blocking to independent state maintenance.
2Ease of operation
If a single frequency control signal is used to drive both power elements, then the control process is simplified, but additional signals are traditionally needed to block both elements simultaneously
Solution Approach 1:
The patent merges the control functions into a single frequency control signal that simultaneously drives both power elements. By using complementary switching where one element is on when the other is off, the single control signal achieves both the AC generation during operation and the current extinction during shutdown, eliminating the need for separate blocking signals.
Solution Approach 2:
Instead of the conventional approach of actively blocking both elements to extinguish current, the patent inverts the approach by maintaining one element in the on-state and the other in the off-state. This inversion achieves current extinction through the natural circuit behavior rather than active dual-blocking, simplifying the control signal requirements.
3Device complexity
If one power element is maintained in on-state and the other in off-state during current extinction, then the control process is simplified, but safety concerns may arise compared to simultaneous blocking
Solution Approach 1:
The patent introduces a freewheeling diode as an intermediary element that provides a safe current path during the extinction phase. When one power element is turned off while the other remains on, the diode ensures that inductive current has a controlled path to decay, preventing voltage spikes and ensuring system safety without requiring simultaneous blocking of both elements.
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
Simplifies the control of power elements, reduces the need for additional control signals, and ensures safe operation by using a single frequency signal for both generating and extinguishing the alternating current, while preventing short-circuits by securing the power elements in a blocked state.
Implementation Method 1
generate an alternating electric current in an inductor
Implementation Method 2
alternately position the two power elements respectively in a conducting state and a blocked state
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A control device for two power elements (T1, T2) mounted in a half-bridge configuration to generate an alternating electric current in an inductor (L) includes means (30) for controlling the two power elements (T1, T2) by means of a frequency control signal adapted to alternately position the two power elements (T1, T2) in a conducting state and a blocking state, respectively. During a step of switching off the alternating electric current generated in the inductor (L), one of the two power elements (T1; T2) is held in a conducting state and the other of the two power elements (T2; T1) is held in a blocking state. This device is used, in particular, in an induction cooking appliance.