Current Sense Circuit Precharge for Faster Settling
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Solution Overview
Problem
Current sensing in power converters, particularly in switched-mode power converters, is hindered by ringing phenomena that lead to increased settling times, negatively affecting the accuracy and efficiency of current regulation.
Innovation Solution
A current measurement circuit that adjusts its start measurement value based on a measurement value obtained in a preceding measurement cycle, reducing settling time by ensuring a more accurate representation of the load current at the beginning of each measurement window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the current sense circuit is activated during predefined time periods to avoid ringing, then the harmful effect of ringing is reduced, but the settling time increases and measurement precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-charging the holding capacitor to the measurement value from the previous measurement cycle before the new measurement begins. This preliminary setup eliminates the need for the capacitor to charge from zero during the measurement window, thereby reducing settling time and allowing accurate measurement even during periods when ringing is present.
2Object-affected harmful factors
If the current sense circuit is activated during predefined time periods to avoid ringing, then the harmful effect of ringing is reduced, but the settling time increases and productivity decreases
Solution Approach 1:
The holding capacitor is pre-charged to the previous measurement value before the new measurement cycle starts, so that the measurement can begin immediately without waiting for the capacitor to charge from zero. This preliminary action significantly reduces settling time and improves measurement speed.
Solution Approach 2:
The patent maintains continuous measurement capability by using the previous measurement value to pre-charge the holding capacitor, ensuring that each measurement cycle can start immediately without idle settling time. This creates a continuous measurement process that improves productivity.
3Loss of time
If the start measurement value is adjusted based on preceding measurement cycle, then settling time is reduced, but device complexity increases
Solution Approach 1:
The patent uses feedback by taking the measurement value from the previous measurement cycle and using it to pre-charge the holding capacitor for the next measurement. This feedback mechanism allows the circuit to adapt to changing current conditions and reduces settling time without requiring complex additional hardware.
Solution Approach 2:
The holding capacitor copies the previous measurement value and uses it as the starting point for the new measurement cycle. This copying approach simplifies the circuit by reusing existing measurement data rather than requiring complex initialization logic.
Data Source
AI summary
A method for measuring current in a conductor, a current measurement circuit, and a power converter with a current measurement circuit are disclosed. The method includes measuring a current (IL) in a conductor in successive measurement cycles using a current measurement circuit (2). Measuring the current (IL), in each measurement cycle, comprises adjusting a start measurement value of the measurement circuit (2) based on a measurement value obtained in a preceding measurement cycle.