MOSFET Switching Board Layout for Bidirectional Current Shut-Off
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Solution Overview
Problem
Conventional switching boards for automotive vehicles, which use mechanical relays, are complex and prone to noise due to parasitic diodes in MOSFETs, making them unsuitable for efficient current shut-off and miniaturization.
Innovation Solution
A simply configured switching board with a circuit comprising an insulating plate, control circuit, busbars, and semiconductor switching elements, where the connection busbar includes a reinforcing portion and heat radiation plate, allowing efficient current handling and heat dissipation without enlarging the board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical relays are used in the switching board, then the board can handle large currents, but the structure becomes complex and noise increases
Solution Approach 1:
The patent replaces mechanical relays with semiconductor switching elements (MOSFETs) to eliminate mechanical moving parts, reducing structural complexity and noise while maintaining current handling capability through proper circuit configuration with multiple MOSFETs connected in parallel
2Device complexity
If semiconductor switching elements are used to replace mechanical relays, then miniaturization and noise reduction are achieved, but current shut-off in both directions becomes difficult due to parasitic diodes
Solution Approach 1:
The patent divides the current path into multiple segments by connecting multiple MOSFETs in series, with each MOSFET's parasitic diode oriented in opposite directions. This segmentation allows complete bidirectional current shut-off while maintaining a relatively simple overall structure
Solution Approach 2:
The patent uses asymmetric arrangement of MOSFETs with opposite polarities, where the parasitic diodes of adjacent MOSFETs are oriented in opposite directions. This asymmetric configuration enables the circuit to block currents flowing in both directions simultaneously
3Device complexity
If MOSFETs are used with parasitic diodes, then the switching board can be simplified, but current cannot be completely shut off in both directions
Solution Approach 1:
The patent converts the harmful effect of parasitic diodes into a beneficial feature by deliberately arranging MOSFETs with opposite polarities in series. The parasitic diodes that would normally cause unwanted current flow are instead configured to block currents in both directions, transforming a potential defect into a functional advantage for bidirectional current control
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 solution provides a compact, efficient, and noise-reduced switching board capable of handling large currents and preventing current flow in both directions, enhancing fuel economy and reducing battery deterioration by efficiently managing power between the main and auxiliary power supplies.
Implementation Method 1
a gate terminal connected to a control circuit; wherein some semiconductor switching elements are first semiconductor switching elements arranged inside the first mounting windows and having drain terminals connected to parts of the input busbar, source terminals connected to parts of the connection busbar and gate terminals connected to the control circuit
Implementation Method 2
a parasitic diode by a p-n junction is generated between a source and a drain. Accordingly, even if a gate is turned off, a current flows from a source side to a drain side through this parasitic diode
Implementation Method 3
the connection busbar includes a reinforcing portion and heat radiation plate
Data Source
AI summary
A switching board is provided with a control circuit board including a control circuit, first mounting windows and second mounting windows, a circuit constituent including an input busbar, an output busbar and a connection busbar arranged on one surface of the control circuit board, and first and second semiconductor switching elements. The first semiconductor switching elements are arranged inside the first mounting windows and have drain terminals connected to the input busbar, source terminals connected to the connection busbar and gate terminals connected to the control circuit. The second semiconductor switching elements are arranged inside the second mounting windows and have drain terminals connected to the output busbar, source terminals connected to the connection busbar and gate terminals connected to the control circuit.