Rapid Current Measurement System with Dynamic Gain Adjustment
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Solution Overview
Problem
Current measurement systems face challenges in accurately and rapidly responding to wide-ranging current levels, particularly in automotive battery systems, where sudden increases in current can lead to over-ranging issues with analog-to-digital converters, resulting in delayed and inaccurate measurements.
Innovation Solution
A rapid response measurement system that includes a programmable gain amplifier and an over-range detector with a faster output rate than the analog-to-digital converter, allowing for immediate detection of signal over-ranging and adjustment of gain and conversion rate to bring the signal back within the valid range, thereby reducing measurement latency and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-gain amplifier is used to amplify low-level current signals for accurate ADC conversion, then measurement precision is improved, but the system becomes unable to rapidly respond to sudden large current increases because the amplified signal exceeds the ADC full-scale range
Solution Approach 1:
The patent implements dynamic gain adjustment by switching between multiple gain stages (first gain stage for low currents, second gain stage for high currents) based on real-time current level detection. This dynamic adaptation allows the system to maintain high measurement precision across the full current range while rapidly responding to current changes without signal clipping
Solution Approach 2:
The system changes the amplification parameter (gain) based on the measured current level. When current exceeds a threshold, the gain is reduced to prevent ADC overflow; when current is low, the gain is increased to maximize measurement resolution. This parameter adaptation resolves the contradiction between precision and response speed
2Measurement precision
If the ADC conversion rate is slowed down to minimize noise effects for accurate low-current measurements, then measurement precision is improved, but the system cannot rapidly detect and respond to sudden large current increases
Solution Approach 1:
The patent dynamically adjusts the ADC conversion rate based on current conditions. During normal low-current operation, a slower conversion rate is used to minimize noise and maximize precision. When a current surge is detected, the system switches to a faster conversion rate to rapidly track and measure the changing current, thereby reducing measurement latency during critical events
3Device complexity
If a single fixed gain setting is used in the amplifier, then device complexity is reduced, but the system cannot accurately measure both low-level and high-level currents within the ADC full-scale range
Solution Approach 1:
The patent employs multiple gain stages with switchable configurations rather than a single fixed gain amplifier. The system dynamically selects between a first gain stage (for low currents) and a second gain stage (for high currents) based on the measured signal level, enabling accurate measurement across a wide current range while maintaining manageable system complexity through structured modular design
Data Source
AI summary
A rapid response measurement is accomplished by providing to a programmable gain amplifier an input to be measured, providing to an analog to digital converter having a predetermined output rate, the output from the programmable gain amplifier, determining when the output is greater than full scale input range of the analog to digital converter in an interval shorter than the period of the predetermined output rate of the analog to digital converter and adjusting the gain of the programmable gain amplifier to reduce the output below the full scale of the analog to digital converter at a rate faster than the predetermined output rate of the ADC.