Current Sampling Integrator Circuit for Energy Storage Aliasing Error Reduction
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Solution Overview
Problem
Current methods for state of charge estimation in energy storage devices are hindered by aliasing errors, which require frequent corrections and are not easily adaptable to varying applications due to the need for application-specific anti-aliasing filter designs.
Innovation Solution
A current sampling system that integrates the current signal to produce a charge signal, which is then sampled and differentiated to generate an anti-aliased current signal, eliminating the need for additional digital anti-aliasing filters and allowing for adaptable sampling across different applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an application-specific anti-aliasing filter is designed and implemented, then aliasing errors are minimized, but the system becomes expensive and time-consuming to adapt to varying applications
Solution Approach 1:
The patent implements a universal sampling system that can be applied across multiple energy storage applications without requiring application-specific customization. The system uses a fixed analog anti-aliasing filter combined with a digital resampling stage that adapts to different applications through software configuration rather than hardware changes, making the same hardware platform suitable for various energy storage applications.
Solution Approach 2:
The patent introduces a digital resampling stage as an intermediary between the fixed analog anti-aliasing filter and the final sampling. This digital intermediary allows the system to maintain a fixed analog filter design while adapting to different applications through digital signal processing, eliminating the need for expensive and time-consuming hardware reconfiguration.
2Measurement precision
If a fixed analog anti-aliasing filter is used with high sampling rate, then aliasing is avoided, but hardware reconfiguration for different applications is not feasible
Solution Approach 1:
The patent replaces the mechanical/analog approach of reconfiguring hardware filters with a digital signal processing approach. Instead of physically changing the analog filter characteristics for different applications, the system uses a fixed analog filter combined with digital resampling that can be software-configured to adapt to different applications, making the system easier to manufacture and deploy.
3Measurement precision
If current measurement is performed with integration, then state of charge can be estimated, but bias errors accumulate resulting in large estimation errors
Solution Approach 1:
The patent applies preliminary anti-aliasing filtering before sampling to prevent aliasing errors from contaminating the current measurements. By removing high-frequency components that could alias into the measurement band before the integration process begins, the system prevents a major source of bias errors from accumulating over time, improving the long-term reliability of state of charge estimates.
Data Source
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AI summary
Systems and methods to sample current measurements in energy storage assets while reducing bias errors such as aliasing are provided. One example current sampling system includes an integrator circuit that receives the current signal as an input and integrates the current signal to output a charge signal. The current signal is indicative of a current at an energy storage asset of an energy storage system. The current sampling system includes a charge signal sampler circuit that samples the charge signal at a charge signal sampling rate. The current sampling system includes a differentiator circuit that receives the samples of the charge signal from the charge signal sampler circuit and differentiates the samples of the charge signal to output an anti-aliased current signal.