MOSFET Electronic Off-Switch With Intermittent Charge Pump Control
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Solution Overview
Problem
Conventional pyrotechnically or electromagnetically actuated switches in vehicle electrical systems have limitations such as limited switching cycles, high wear, and unfavorable temporal switching behavior, leading to inefficiencies and potential safety issues, particularly when switching high currents.
Innovation Solution
An electronic isolating switch using a MOSFET as the semiconductor switch, with a control circuit that intermittently operates a charge pump based on gate-source voltage, time, and temperature to minimize power consumption and ensure reliable operation, reducing wear and improving switching precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnically operated switches are used to disconnect the battery, then the disconnect function is achieved, but the switch can only be activated once and reactivation is not possible
Solution Approach 1:
The patent replaces pyrotechnically operated mechanical switches with an electronically operated MOSFET switch. The MOSFET is controlled by electronic signals through a control unit, enabling multiple switching cycles and reactivation capability while maintaining reliable disconnect function. The electronic control system allows the switch to be opened and closed repeatedly based on crash detection signals.
2Adaptability or versatility
If electromagnetically operated switches are used, then the switch can be activated multiple times, but the number of possible switching cycles is limited and wear occurs
Solution Approach 1:
The patent replaces electromagnetically operated mechanical switches with an electronically operated MOSFET switch. The MOSFET has no mechanical moving parts or contacts that wear out, eliminating the limitation on switching cycles. The solid-state electronic component can be switched indefinitely without degradation, significantly extending service life while maintaining multiple activation capability.
3Ease of operation
If electromagnetically actuated switches are used, then the switch can be controlled, but contact bounce occurs and timing is poorly defined
Solution Approach 1:
The patent replaces electromagnetically actuated mechanical switches with an electronically operated MOSFET switch. The MOSFET switching is controlled by electronic signals with precise timing, eliminating contact bounce entirely. The solid-state switch transitions instantly and predictably between states, providing well-defined switching timing controlled by the control unit based on crash detection.
4Reliability
If semiconductor switches are used to replace mechanical switches, then unlimited switching cycles are possible, but the default ON state must be maintained with very low drive power
Solution Approach 1:
The patent implements a charge pump circuit that operates periodically rather than continuously to maintain the MOSFET gate voltage. The control unit monitors system conditions and activates the charge pump only when needed to replenish gate charge, significantly reducing average power consumption while maintaining the MOSFET in its default ON state for unlimited switching cycles.
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 reliable, low-power consumption electronic isolating switch that can handle high currents with improved switching precision and extended service life, enhancing the safety and efficiency of vehicle electrical systems by minimizing power loss and preventing overheating.
Implementation Method 1
The semiconductor switch (110) is an n-channel MOSFET... current flows from source to drain... the gate-source voltage UGS exceeds the threshold voltage Uth
Implementation Method 2
In the OFF state, current can flow through the body diode (111) from source to drain... the source voltage US exceeds the drain voltage UD
Implementation Method 3
a charge pump (130) which has a function of generating a positive voltage... the control circuit (120) connects the gate terminal (G) of the semiconductor switch (110) to the charge pump (130)
Data Source
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AI summary
The switch i.e. electronic off-switch (100), has a charge pump (130) for producing a direct current voltage for controlling a semiconductor switch (110) i.e. MOSFET. A control circuit (120) controls intermittent operation of the pump by alternate activation and deactivation of the pump. The circuit activates or deactivates the pump based on gate-source voltage level of the semiconductor switch. The circuit monitors a gate voltage (UGS) of the semiconductor switch. The circuit activates the pump, when the gate voltage falls below a preset minimal value. Independent claims are also included for the following: (1) a power supply unit for a motor vehicle (2) a method for reversible disconnection of a power supply unit for a motor vehicle at two regions.