Switch Trigger Precharge Circuit for Inrush Current Suppression
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Solution Overview
Problem
Conventional switch control methods suffer from increased heat losses, switch damage, and inability to turn off immediately due to prolonged switching durations, which affect efficiency and protection capabilities.
Innovation Solution
A switch trigger that reduces voltage variation by precharge, suppressing inrush current and enabling zero-voltage switching with short-circuit protection, utilizing components like MOSFETs and BJTs to control switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If soft start of switches is used to suppress inrush current, then inrush current is suppressed, but the duration for turning on the switch increases causing more heat losses and reduced efficiency
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor through a charging circuit before the main switch is turned on. This pre-charging process gradually raises the voltage across the capacitor to match the input voltage, so when the main switch closes, there is no voltage difference and thus no inrush current. The charging circuit is disconnected after pre-charging, allowing the main switch to turn on instantly without prolonged conduction time, thereby avoiding heat losses while still suppressing inrush current.
2Object-affected harmful factors
If soft start of switches is used to suppress inrush current, then inrush current is suppressed, but the switch becomes more susceptible to damage due to prolonged exposure
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor through a charging circuit before the main switch is turned on. This pre-charging process gradually raises the voltage across the capacitor to match the input voltage, so when the main switch closes, there is no voltage difference and thus no inrush current. The charging circuit is disconnected after pre-charging, allowing the main switch to turn on instantly without prolonged conduction time, thereby avoiding heat losses while still suppressing inrush current.
3Object-affected harmful factors
If the duration for turning on the switch is increased, then inrush current is suppressed, but the duration for turning off the switch also increases causing inability to turn off immediately for protection
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor through a charging circuit before the main switch is turned on. This pre-charging process gradually raises the voltage across the capacitor to match the input voltage, so when the main switch closes, there is no voltage difference and thus no inrush current. The charging circuit is disconnected after pre-charging, allowing the main switch to turn on instantly without prolonged conduction time, thereby avoiding heat losses while still suppressing inrush current.
4Device complexity
If conventional switch control is used, then switching is simple, but efficiency is reduced due to heat losses
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor through a charging circuit before the main switch is turned on. This pre-charging process gradually raises the voltage across the capacitor to match the input voltage, so when the main switch closes, there is no voltage difference and thus no inrush current. The charging circuit is disconnected after pre-charging, allowing the main switch to turn on instantly without prolonged conduction time, thereby avoiding heat losses while still suppressing inrush current.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A switch trigger (1) is provided. The switch trigger (1) includes input and output terminals (11, 12), first and second switches (Q1, Q2), a bypass resistor (R1), an output capacitor (Co), a diode (D), a discharging resistor (R2), and first and second divider resistors (R3, R4). The first switch (Q1) has two terminals respectively and electrically connected to the input and output terminals (11, 12). The bypass resistor (R1) is electrically connected to the input and output terminals (11, 12). The diode (D) has an anode electrically connected to the input terminal (11). The second switch (Q2) has two terminals respectively and electrically connected to a cathode of the diode (D) and a third terminal of the first switch (Q1). The discharging resistor (R2) is electrically connected to the third terminal of the first switch (Q1) and the ground terminal. The first and second divider resistors (R3, R4) are electrically connected in series between the output and ground terminals, and a connection node therebetween is electrically connected to a third terminal of the second switch (Q2).