Parallel Switching Transistors in Quasi-Resonant Inverter Power Supply
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Solution Overview
Problem
Induction cooking appliances are limited in the power they can deliver due to the maximum allowable voltage of switching transistors, which restricts the power that can be induced in cooking vessels, leading to overheating and potential thermal destruction of the transistors when trying to generate higher powers.
Innovation Solution
The use of two switching transistors connected in parallel within a quasi-resonant inverter power supply device, allowing for the distribution of current across both transistors and reducing the risk of overheating, while maintaining a quasi-resonant topology, enabling higher power delivery without exceeding the maximum voltage limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single switching transistor is used in the inverter power supply device, then the device complexity is reduced, but the maximum power that can be induced in the cooking vessel is limited due to voltage constraints
Solution Approach 1:
The patent divides the single switching transistor into multiple parallel switching transistors (first switching transistor and second switching transistor). Each transistor handles a portion of the total current, allowing the system to achieve higher power output while keeping individual transistor voltage ratings manageable. This segmentation resolves the contradiction by enabling higher power without requiring each component to operate at extreme voltage levels.
2Power
If the maximum allowable voltage of the switching transistor is increased to generate higher power, then the power output increases, but the transistor overheats and may be thermally destroyed
Solution Approach 1:
By segmenting the current path into multiple parallel transistors, each transistor operates at lower current density, reducing heat generation and improving thermal stability while maintaining high overall power output capability.
Solution Approach 2:
The patent combines multiple switching transistors in parallel configuration, merging their current-carrying capabilities while distributing the thermal load. This allows the system to achieve high power output equivalent to using a single high-voltage transistor without the thermal destruction risks.
3Power
If the current through the switching transistor is increased to generate higher power, then the power output increases, but the voltage across the transistor terminals exceeds the maximum allowable voltage
Solution Approach 1:
The patent segments the total current into multiple parallel paths through multiple transistors. This allows the system to achieve high total current (and thus high power) while each individual transistor experiences only a fraction of the total current, keeping voltage drops within safe operating limits.
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 allows for increased power generation in cooking vessels while minimizing thermal losses and preventing transistor destruction, enabling the production of induction cooking appliances with higher power outputs without the need for transistors with higher maximum voltage ratings.
Implementation Method 1
inductor means integrated into a resonant circuit
Implementation Method 2
switching transistors connected in parallel, the switching transistors being connected in series with the inducing means
Data Source
Figure 1
Figure 2~3B
AI summary
An inverter power supply device with inductors (L1) integrated into a resonant circuit, with a quasi-resonant topology, comprises at least two switching transistors (T1, T2) connected in parallel, the switching transistors (T1, T2) being connected in series with the inductors (L1). Used particularly in induction cooking appliances.