Current Limiter Circuit With Feedback for Fast Switch-Off
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Solution Overview
Problem
Conventional current limiter circuits face a trade-off between suppressing inrush currents and achieving quick switch-off speeds, as they slow down the gate voltage change, hindering rapid switch-off operations.
Innovation Solution
A current limiter circuit with a controller and negative feedback circuit that includes a capacitor and a gate controller, allowing for independent control of the switch-on and switch-off processes by combining signals from different paths, enabling both current suppression and swift switch-off without compromising speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a low-pass filter formed by a resistor and capacitor is connected to the gate of the FET to suppress inrush current, then the gate voltage changes gradually and inrush current is suppressed, but the switch-off speed becomes slow
Solution Approach 1:
The patent segments the control signal paths by introducing separate first and second signal paths that combine at the controller input. The first path carries the original control signal while the second path carries the negative feedback signal from the output. This segmentation allows independent optimization of turn-on and turn-off characteristics without mutual interference, resolving the contradiction between inrush current suppression and switch-off speed.
Solution Approach 2:
The patent implements negative feedback by routing the output signal back to the controller through the second signal path. The controller combines this feedback signal with the original control signal, automatically adjusting the gate voltage based on actual output conditions. This feedback mechanism suppresses inrush current during turn-on while maintaining fast switch-off capability, as the feedback only activates when output voltage rises.
2Object-generated harmful factors
If the gate voltage is controlled gradually to suppress inrush current, then current suppression is achieved, but the overall response time increases
Solution Approach 1:
The patent makes the control characteristics dynamic by using negative feedback that adapts to different operating states. During turn-on, the feedback gradually adjusts the gate voltage to suppress inrush current. During turn-off, the feedback mechanism automatically changes behavior to allow rapid voltage collapse. This dynamic adaptation eliminates the need for slow gradual control in all situations, reducing overall response time while maintaining current suppression where needed.
Solution Approach 2:
The patent changes the effective control parameters based on operating conditions. The negative feedback signal modifies the gate voltage waveform characteristics - producing gradual changes during turn-on for current suppression, but enabling sharp transitions during turn-off for fast response. This parameter change approach allows the system to optimize both current suppression and response time without compromise.
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 limits inrush currents while maintaining fast switch-off speeds, eliminating the trade-off between current suppression and switch-off speed, and allows for a high degree of freedom in circuit design.
Implementation Method 1
The negative feedback circuit includes an input port coupled to a first node via a capacitor if the capacitor is connected between thereof and the first node
Data Source
AI summary
A current limiter circuit limits a current in a path connecting an input terminal and an output terminal through a switch including a control port, the switch controlling the current to a predetermined value or less. The current limiter circuit includes a gate controller and a negative feedback circuit. The gate controller includes an input port which is connected to a connection point between a first path through which a first signal is transmitted and a second path through which a second signal is transmitted, and receiving the first signal and an output port supplying a control signal to the control port of the switch. The negative feedback circuit includes an input port coupled to a node via a capacitor if the capacitor is connected between thereof and the node provided between the switch and the output terminal and an output port connected to the input port.