Polyphase Energy Meter ADC Segmentation
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Solution Overview
Problem
Existing polyphase electric energy meters face challenges in achieving high accuracy with large die space requirements and high costs, particularly when using separate ADCs for each phase, and in efficiently processing voltage signals with complex multiplexing and demultiplexing.
Innovation Solution
A polyphase electric energy meter design that uses separate high-resolution ADCs for current input signals and a single moderate-resolution ADC for voltage input signals, with a multiplexer and demultiplexer for voltage sampling, allowing for parallel processing of current signals and sequential processing of voltage signals, thereby optimizing die space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate high-resolution ADCs are used for each current and voltage input signal, then measurement precision is improved, but die area and cost increase significantly
Solution Approach 1:
The patent segments the ADC resources by function: separate high-resolution ADCs are allocated exclusively for current signal conversion, while a shared moderate-resolution ADC handles voltage signal conversion. This segmentation allows each ADC type to be optimized for its specific measurement requirements, maintaining high measurement precision for current while reducing overall die area through sharing the voltage ADC across multiple phases.
Solution Approach 2:
The patent implements a universal ADC architecture where a single ADC is shared across multiple voltage input channels through time-multiplexing. The same ADC resource serves multiple functions (converting voltage signals from different phases), reducing the total number of ADCs required while maintaining measurement accuracy through proper sampling and correction techniques.
2Area of stationary object
If a single ADC with multiplexer is used for all input signals, then die area is reduced, but device complexity increases due to phase correction requirements
Solution Approach 1:
The patent segments the conversion architecture into dedicated current ADC paths and shared voltage ADC paths. Current signals use separate ADCs without requiring complex phase correction, while voltage signals use a shared ADC with simpler correction requirements. This segmentation reduces overall device complexity compared to a fully sequential approach while maintaining area efficiency.
3Measurement precision
If high-resolution ADCs are used for voltage signals with small dynamic range, then measurement precision is improved, but resource allocation becomes inefficient
Solution Approach 1:
The patent applies local quality by matching ADC resolution to the specific requirements of each signal type: high-resolution ADCs are used where needed (current signals with large dynamic range), while moderate-resolution ADCs suffice for voltage signals with small dynamic range. This localized optimization improves resource allocation efficiency without compromising measurement precision where it is most critical.
Data Source
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AI summary
A polyphase electric energy meter comprises a microcontroller with a front end that converts analog current input signals and analog voltage input signals to digital current and voltagesamples for processing by the microcontroller. The front end includes separate input channels, each for one of the current input signals with a sigma-delta modulator followed by a decimation filter. The front end further includes a common input channel for all voltage input signals with a multiplexer, an analog-to-digital converter and a demultiplexer. The separate input channels and the common input channel provide the digital current and voltage samples for processing by the microcontroller.