Drive Device Bypass Circuits Mitigate Induced Electromotive Forces
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Solution Overview
Problem
Existing drive devices for semiconductor elements face malfunctions due to induced electromotive forces caused by parasitic inductance during switching operations, particularly when multiple semiconductor elements are coupled via a main electrode unit and driven by a common control signal, as existing solutions do not effectively mitigate these forces.
Innovation Solution
A drive device comprising an input buffer, bypass circuits, and drive circuits with specific impedance matching and filtering configurations to attenuate high-frequency signals, ensuring that the induced electromotive force does not affect the switching operation of semiconductor elements, and an AC power supply device incorporating these components to manage the common drive control signal across multiple semiconductor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple semiconductor elements are coupled in parallel via a main electrode unit and driven by a common control signal, then the productivity and power output are improved, but the induced electromotive force from parasitic inductance increases causing malfunctions and destruction
Solution Approach 1:
The patent divides the common control signal path into separate control signal paths for each semiconductor element. Each path includes its own control signal line and level shift circuit, isolating the control signals from each other and from the high-voltage main electrodes. This segmentation prevents the induced electromotive force from affecting all elements simultaneously and allows independent control of each element's switching timing
Solution Approach 2:
The patent introduces level shift circuits as intermediary components between the control signal source and the semiconductor element control electrodes. These level shift circuits translate the low-voltage control signals to the appropriate voltage levels for each semiconductor element while providing electrical isolation. The main electrode unit also serves as an intermediary that couples reference potentials while allowing the bypass circuit to mitigate induced voltages
2Device complexity
If a common drive control signal is used for multiple semiconductor elements, then the device complexity is reduced, but the induced electromotive force causes synchronized malfunctions across all elements
Solution Approach 1:
The patent segments the common control signal into separate control signal paths, with each path having its own level shift circuit and control signal line. This segmentation maintains the simplicity of using a common control source while preventing synchronized malfunctions by isolating each element's control path from induced electromotive forces
Solution Approach 2:
The level shift circuits perform preliminary voltage level translation and isolation before the control signals reach the semiconductor element control electrodes. This preliminary action prepares the control signals to be immune to subsequent induced electromotive forces during switching operations
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 proposed solution effectively reduces the influence of induced electromotive forces on semiconductor elements, preventing malfunctions and allowing for synchronized switching operations across multiple elements, thereby enhancing the reliability and flexibility of the drive device.
Implementation Method 1
when the semiconductor element performs a switching operation to supply intermittently an output current, an induced electromotive force occurs in a parasitic inductance
Data Source
AI summary
A first bypass circuit has first and second nodes. The first load circuit is connected between the first node and a signal input terminal of the second drive circuit. The second load circuit has substantially the same impedance as the first load circuit, and is connected between the second node and the reference potential terminal of the second drive circuit. The first drive circuit has the same reference potential as the input buffer. The second bypass circuit passes a signal of a predetermined frequency or higher between a current path formed between the first load circuit and the signal input terminal of the second drive circuit and a current path formed between the second load circuit and the reference potential terminal of the second drive circuit. The first bypass circuit passes a signal of a predetermined frequency or higher between the first and second nodes.