Input Control Circuit With Sense Capacitor For Inrush Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converter designs face challenges in efficiently managing inrush current, under voltage, and over voltage conditions, particularly with large input capacitors, leading to inefficiencies, increased costs, and complex circuitry due to the need for direct current sensing and electrical isolation.
Innovation Solution
An input control circuit that uses a series switch, sense capacitor, current sense mirror, and clamp circuit to adjust input current based on a signal proportional to the input current, allowing for inrush current limiting, under voltage lockout, over voltage protection, and remote enable functionality without direct current sensing, thereby reducing power loss and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct current sensing is employed to control inrush current, then inrush current can be accurately controlled, but power loss increases and circuit complexity increases
Solution Approach 1:
The patent introduces an intermediary capacitor connected in parallel with the input capacitor to sense voltage changes. This capacitor acts as a mediator that translates voltage changes into current information without requiring direct current sensing, thereby reducing power loss while maintaining control accuracy.
Solution Approach 2:
The patent replaces the traditional electrical current sensing mechanism with a voltage-based sensing approach using a capacitor. This substitution eliminates the need for high-power current sensors and their associated power losses, achieving the same control function through a different physical mechanism.
2Reliability
If direct current sensing is employed to control inrush current, then inrush current can be accurately controlled, but circuit complexity increases
Solution Approach 1:
The patent introduces an intermediary capacitor connected in parallel with the input capacitor to sense voltage changes. This capacitor acts as a mediator that translates voltage changes into current information without requiring direct current sensing, thereby reducing power loss while maintaining control accuracy.
Solution Approach 2:
The patent replaces the traditional electrical current sensing mechanism with a voltage-based sensing approach using a capacitor. This substitution eliminates the need for high-power current sensors and their associated power losses, achieving the same control function through a different physical mechanism.
3Reliability
If electrical isolation requirements are addressed, then safety is improved, but cost increases
Solution Approach 1:
The patent introduces an intermediary capacitor connected in parallel with the input capacitor to sense voltage changes. This capacitor acts as a mediator that translates voltage changes into current information without requiring direct current sensing, thereby reducing power loss while maintaining control accuracy.
4Object-generated harmful factors
If large input capacitors are used, then noise filtering is improved, but inrush current increases
Solution Approach 1:
The patent employs a feedback mechanism where the voltage across the intermediary capacitor is continuously monitored and fed back to the series switch control circuit. This feedback enables real-time adjustment of the series switch to limit inrush current while allowing the large input capacitor to provide effective noise filtering.
Solution Approach 2:
The patent implements preliminary action by using the intermediary capacitor to detect voltage changes before they result in excessive inrush current. The control circuit anticipates the inrush current condition and adjusts the series switch in advance to prevent excessive current flow, while still allowing the large input capacitor to perform its noise filtering function.
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 solution enables efficient inrush current limiting, improved transient response, reduced circuit complexity, and lower costs by using shared circuitry for multiple functions, ensuring reliable operation with high-capacitance-density devices and minimizing electrical stresses.
Implementation Method 1
a sense capacitor electrically coupled in parallel with an input filter capacitor between the input line and a ground reference to develop a signal that is proportional to the input current
Implementation Method 2
a current sense mirror electrically coupled to the sense capacitor to receive the signal that is proportional to the input current
Data Source
AI summary
Control circuitry handles inrush current, and may provide under voltage and/or over voltage monitoring and handling, as well as remote enable handling. The circuitry may advantageously employ a sense capacitor in parallel with an input capacitor (e.g., bulk input filter capacitor), and a current mirror to produce a signal proportional to input current. A clamp circuit may control a series pass device to regulate current in response to the proportional signal, or to interrupt current flow in response to an under voltage or over voltage condition or receipt of a signal indicative of a disable state. An enable signal may be summed into a comparator that handles under voltage condition determination.