Vehicle Solid-State Switch Driving Circuit for Inrush and Surge Control
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Solution Overview
Problem
Conventional vehicle power switches face issues with excessive inrush current and surge voltage when turned on or off, leading to potential damage to the relay contacts and peripheral circuits, and a risk of short circuits due to constant voltage application to the coil.
Innovation Solution
A solid-state switch driving circuit employing an oscillation circuit, Field Effect Transistors (FETs), time constant circuits, and reverse voltage protection diodes to control and regulate the application of power to a load, preventing excessive inrush current and surge voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power relay is used to control power application to a load, then the switch can be turned on and off, but excessive inrush current damages the relay contact and surge voltage damages peripheral circuits
Solution Approach 1:
The patent replaces the mechanical relay system with a solid-state power switch (MOSFET or IGBT) controlled by a driving circuit. The solid-state switch uses electronic field control instead of mechanical contact movement, eliminating contact damage from inrush current and surge voltage while maintaining the power switching function.
Solution Approach 2:
The patent introduces a driving circuit as an intermediary between the control signal and the power switch. This driving circuit includes protection components such as diodes and resistors that mediate the power application process, preventing direct inrush current and surge voltage from reaching the switch and peripheral circuits.
2Reliability
If voltage is always applied to the coil of the power relay, then the relay can be driven, but a short circuit may occur between the coil and ground
Solution Approach 1:
The patent applies voltage to the solid-state power switch coil periodically through an oscillation circuit rather than continuously. The oscillation circuit generates square wave signals that periodically energize and de-energize the coil, preventing constant voltage application and reducing the risk of short circuits between the coil and ground.
Solution Approach 2:
The patent changes the voltage application parameter from constant DC voltage to periodic square wave voltage. This parameter change is achieved through the oscillation circuit and time constant circuits that control the timing and duration of voltage application to the coil, improving reliability by avoiding continuous stress on the coil insulation.
3Productivity
If a conventional power relay is used, then power can be switched to a load, but the device size is larger compared to solid-state switches
Solution Approach 1:
The patent replaces the bulky mechanical relay structure with a compact solid-state power switch and integrated driving circuit. The solid-state components occupy significantly less space while providing the same power switching capability, thereby reducing overall device volume.
Solution Approach 2:
The patent integrates the driving circuit components (oscillation circuit, time constant circuits, protection diodes) with the solid-state power switch into a compact unified structure. This merging of functions into a single integrated assembly reduces the overall device size compared to separate relay components.
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 effectively prevents damage to circuits and reduces the risk of short circuits by managing power application, ensuring stable operation and minimizing product size compared to coil-type relays.
Implementation Method 1
a first Field Effect Transistor (FET) (129) connected to an output of the oscillation circuit and configured to have a drain connected to a battery via a resistor (123) and a source grounded and configured to output the square waves in response to output of the oscillation circuit; a second FET (113) configured to have a gate connected to output of the first FET (129) and to be selectively turned on and off by the first FET (129)
Implementation Method 2
a reverse voltage protection diode (101) configured to have an N pole connected in series to the first time constant circuit and a P pole connected to the battery
Implementation Method 3
a first time constant circuit connected to the drain of the second FET (113) and the drain of the third FET (115), and configured to have one side connected to the battery via a diode; a second time constant circuit configured to have one side connected to the first time constant circuit and the reverse voltage protection diode (101), another side connected to a gate of the solid-state power switch (117), and yet another side grounded
Data Source
AI summary
Disclosed herein is a solidstate switch driving circuit for a vehicle. The solidstate switch driving circuit includes an oscillation circuit, a constant voltage circuit, a first Field Effect Transistor (FET), a second FET, a third FET configured, a first time constant circuit, a first time constant circuit, a reverse voltage protection diode, a solidstate power switch, and a second time constant circuit. The first time constant circuit is connected to the drain of the second FET and the drain of the third FET. The reverse voltage protection diode has an N pole and a P pole. The solidstate power switch selectively turns on and off power applied to the load. The second time constant circuit has one side connected to the first time constant circuit and the reverse voltage protection diode, and another side connected to a gate of the solidstate power switch.