Overcurrent Protection Device Using Leading Edge Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing overcurrent protection devices in power supplies suffer from propagation delays, resulting in varying protection voltages for different input voltages, which can lead to distinct output powers and increased risk of damage during overcurrent conditions.
Innovation Solution
The implementation of a compensating current unit and a comparator that generates a current sense compensation signal, allowing for earlier detection of overcurrent conditions and uniform overcurrent protection across varying input voltages by comparing the compensated signal with a reference voltage, thereby controlling the power switch effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional overcurrent protection scheme is used with a comparator and pulse width modulation control unit, then the current can be kept within a proper range by comparing the current sensing signal with a reference voltage, but the protection voltage varies for different input voltages due to propagation delay time
Solution Approach 1:
The patent applies preliminary action by generating a leading edge compensation signal that anticipates the propagation delay. The compensation signal is generated in advance and added to the current sensing signal before comparison, so that the overcurrent protection activates at the correct voltage level despite the inherent delay in the control circuit. This ensures consistent protection voltage across different input voltages.
Solution Approach 2:
The patent uses feedback by continuously monitoring the current sensing signal and comparing it with the reference voltage through the comparator. The pulse width modulation control unit adjusts the power switch duty cycle based on the comparison result, creating a closed-loop feedback system that maintains stable overcurrent protection. The feedback mechanism ensures that any variations in input voltage are compensated to maintain consistent protection characteristics.
2Adaptability or versatility
If the power supply operates over a wide range of input voltages, then the adaptability is improved, but the protection voltage varies obviously leading to distinct output powers
Solution Approach 1:
The leading edge compensation signal is generated in advance to counteract the propagation delay effect. By adding this compensation signal to the current sensing signal before the comparison operation, the system achieves uniform protection voltage across the entire input voltage range from 90 Vac to 264 Vac, eliminating the variation that would otherwise occur with wide voltage adaptability.
Solution Approach 2:
The patent changes the parameter of the current sensing signal by adding the leading edge compensation signal to it. This parameter modification ensures that the compensated current sensing signal reaches the reference voltage threshold at the correct moment, maintaining consistent protection voltage levels regardless of input voltage variations, thus enabling wide adaptability without sacrificing precision.
3Ease of operation
If there is propagation delay time in the control circuit, then the power switch can be controlled to turn off, but the current exceeds the predetermined value during the delay period causing power loss
Solution Approach 1:
The patent applies preliminary action by generating the leading edge compensation signal in advance to offset the propagation delay. This compensation signal is added to the current sensing signal before comparison, causing the comparator to trigger earlier. As a result, the power switch turns off before the current can exceed the predetermined value during the delay period, eliminating energy loss while maintaining ease of power switch control.
Solution Approach 2:
The leading edge compensation signal serves as a preliminary anti-action against the harmful effect of propagation delay. By anticipating and counteracting the delay effect through signal compensation, the system prevents the current from rising to dangerous levels during the control response time, thereby preventing energy loss without complicating the power switch control mechanism.
Data Source
AI summary
An overcurrent protection device for a power supply device includes a receiving end for receiving a current sensing signal, a compensating current unit coupled to the receiving end for compensating the current sensing signal in order to generate a current sense compensation signal, a first reference voltage generator for generating a first reference voltage, a comparator coupled between the compensating current unit and the first reference voltage generator for comparing the current sense compensation signal with the first reference voltage in order to generate a comparison result, a control unit coupled to the comparator for controlling a power switch of the power supply device according to the comparison result.