Power Transistor Avalanche Switch-Off Without Clamping Circuits
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Solution Overview
Problem
Power transistor circuits face voltage increases due to stored energy in parasitic inductances when switching off, leading to potential damage and requiring additional clamping circuits for energy dissipation, which increase cost and complexity.
Innovation Solution
Operating power transistors in an Avalanche mode during switching off to dissipate stored energy within the transistors, eliminating the need for external clamping circuits by clamping voltage to the Avalanche breakdown level until energy is dissipated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamping circuit is connected in parallel with the power transistor circuit to clamp voltage and dissipate stored energy, then the voltage across the power transistor is limited to a safe level, but the cost and complexity of the overall circuit increases
Solution Approach 1:
The power transistor circuit dissipates its own stored energy through Avalanche mode operation, eliminating the need for external clamping circuits. The transistor's intrinsic Avalanche capability allows it to handle the voltage spike and dissipate energy internally, making the circuit self-protecting and reducing overall system complexity
Solution Approach 2:
The invention extracts and utilizes the Avalanche breakdown capability that is already present in the power transistor structure. By deliberately allowing the transistor to operate in Avalanche mode, the harmful voltage spike is converted into a controlled energy dissipation mechanism within the transistor itself, removing the need for separate protective components
2Productivity
If the power transistor circuit is switched off, then the circuit interruption function is achieved, but the stored energy in parasitic inductances causes voltage increase that may damage the transistor
Solution Approach 1:
The invention converts the harmful voltage spike caused by parasitic inductance into a beneficial controlled Avalanche breakdown event. The energy that would otherwise damage the transistor is instead dissipated in a controlled manner through the transistor's Avalanche mode, transforming a potential failure mechanism into a protective feature that enables fast switching without compromising reliability
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
Effectively manages energy dissipation within the power transistors, reducing the risk of damage and eliminating the need for costly clamping circuits, thereby simplifying the circuit design and operation.
Implementation Method 1
operating at least one power transistor included in the power transistor circuit in an Avalanche mode so that at least a portion of energy stored in the electronic circuit before switching off the power transistor circuit is dissipated in the at least one power transistor
Data Source
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AI summary
A method is disclosed. The method include switching off a power transistor circuit (1) in an electronic circuit. The electronic circuit includes a power source (2), a load circuit (3), and the power transistor circuit (1) connected between the power source (2) and the load circuit (3). Switching off the power transistor circuit (1) includes operating at least one power transistor (10; 101, 10n) included in the power transistor circuit (1) in an Avalanche mode so that at least a portion of energy stored in the electronic circuit before switching off the power transistor circuit (1) is dissipated in the at least one power transistor.