MOSFET Battery Switching Circuit for Inrush-Free HV Control
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Solution Overview
Problem
High-voltage battery systems face challenges in safe on/off control due to high voltages and currents, requiring specialized assembly and handling, and conventional systems often necessitate pre-charging circuits to manage electrical current inrush.
Innovation Solution
A circuit design incorporating switches and diodes that allow batteries to be turned on sequentially, reducing energy inrush and enabling safe shutdown by diverting inductive current through diodes, eliminating the need for pre-charging circuits and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional battery systems use solid state or mechanical disconnects to withstand high voltages and currents, then safety is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces mechanical disconnects with electronic MOSFET switches that can be controlled to open or close circuits. This substitution eliminates the need for complex mechanical switching mechanisms while maintaining the ability to safely disconnect high-voltage battery systems. The electronic switches provide more reliable and controllable disconnection compared to mechanical systems.
2Reliability
If pre-charging circuits are added to manage electrical current inrush, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a sequential switching strategy where batteries are turned on one at a time rather than simultaneously. This preliminary action of staged activation prevents sudden current inrush that would occur with simultaneous switching. By controlling the timing of each battery connection, the system manages electrical stress without requiring additional pre-charging circuits.
3Loss of energy
If batteries are turned on sequentially to reduce energy inrush, then loss of energy is reduced, but productivity decreases
Solution Approach 1:
The patent uses dynamically controllable MOSFET switches that can be rapidly activated in sequence. The sequential switching is implemented with fast electronic control that minimizes the total startup time. While batteries are activated one at a time rather than simultaneously, the electronic switching speed ensures that the overall process remains efficient and does not significantly impact system productivity.
4Reliability
If diodes are used to divert inductive current during shutdown, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent utilizes diodes to capture and redirect inductive kickback current that naturally occurs during switch shutdown. Instead of viewing the inductive spike as a harmful effect to be eliminated, the circuit is designed to channel this energy through diodes into safe dissipation paths. This converts the potentially damaging inductive effect into a controlled energy management feature that protects the MOSFET switches.
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
This approach safely controls high-voltage battery systems by gradually increasing power, reducing energy inrush during startup and managing inductive kickback during shutdown, thereby simplifying handling and operation without the need for pre-charging circuits.
Implementation Method 1
managing inductive kickback during shutdown
Implementation Method 2
diverting inductive current through diodes
Implementation Method 3
gradually increasing power
Data Source
AI summary
A circuit includes a first switch and a second switch. The first switch includes a source, a gate, a drain, and a first diode. The source of the first switch is connected to an anode of the first diode. The gate of the first switch is connected to a positive terminal of a first battery. The drain of the first switch is connected to a cathode of the first diode and to the positive terminal of the first battery. The second switch has an opposite polarity to the first switch. The second switch includes a source, a gate, a drain, and a second diode. The source of the second switch is connected to an anode of the second diode and to the source of the first switch. The gate of the second switch is connected to the gate of the first switch.