Current Comparison Circuit for Accurate Inductor Current Sensing
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Solution Overview
Problem
Existing power converters face challenges in accurately determining inductor current under different duty cycles, leading to deviations in reconstructed current and affecting output quality due to insufficient time for sampling during short off periods of the main switch transistor.
Innovation Solution
A current comparison circuit that selects between inductor current detection and current reconstruction signals based on DC input and output voltages to determine the appropriate detection signal source, allowing accurate inductor current information acquisition under varying duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the off time of the main switch transistor is shortened to increase switching frequency, then the power conversion efficiency is improved, but the sampling time for inductor current detection becomes insufficient leading to current detection inaccuracies
Solution Approach 1:
The patent performs current detection during the on-time of the main switch transistor before the off-time begins. By preliminarily completing the detection action during the available on-time period, the system ensures accurate current sampling is achieved before the switching cycle progresses to the off-time phase, resolving the contradiction between high switching frequency and sufficient detection time
Solution Approach 2:
The patent dynamically adjusts the detection timing and signal selection based on the actual switching state. The control circuit selectively uses either the inductor current detection signal during on-time or the current reconstruction signal during off-time, creating a dynamic adaptation mechanism that optimizes detection accuracy across varying switching conditions and frequencies
2Power
If the duty cycle is increased to improve power output, then the power conversion capability is enhanced, but the off time becomes insufficient for accurate current sampling
Solution Approach 1:
The system performs current detection during the on-time period before the off-time begins. By completing the detection action preliminarily during the extended on-time associated with high duty cycles, the patent ensures accurate current sampling is achieved before the shortened off-time period begins, resolving the contradiction between high power output and sufficient sampling time
Solution Approach 2:
The patent changes the detection parameter selection based on the duty cycle condition. When duty cycle is high and off-time is short, the system switches to using the current reconstruction signal or adjusts detection timing to occur during on-time, effectively adapting the detection parameters to maintain accuracy across varying power output requirements
3Device complexity
If a single current detection method is used for all duty cycles, then the device complexity is reduced, but the current detection accuracy deteriorates under varying duty cycles
Solution Approach 1:
The patent implements a universal current detection system that can operate in multiple modes. The detection circuit is designed to handle both direct inductor current detection and current reconstruction methods, allowing a single circuit to serve multiple detection functions across different duty cycle conditions, resolving the contradiction between simplicity and accuracy
Solution Approach 2:
The system dynamically selects between different detection methods based on duty cycle conditions. The control circuit automatically switches between using the inductor current detection signal and the current reconstruction signal, creating a dynamic adaptation mechanism that maintains detection accuracy across varying operating conditions without requiring separate fixed circuits for each mode
Data Source
AI summary
The present application provides a power converter and a current comparison circuit, in which a judgment module and a selector are set to select one of the inductor current detection signal or the current reconstruction signal with a predetermined slope of the power converter according to the DC input voltage and DC output voltage of the power converter as a detection signal, and a comparison signal for adjusting the duty cycle of the switching control signal of the power converter is generated by comparing the detection signal with the first reference voltage, so that the inductor current information of the system can be accurately obtained under different duty cycles of the switching control signal, which facilitates accurate control of the system and improves output quality, and is easy to implement and cost-effective.