Shunt Current Measurement with Dynamic Oversampling
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Solution Overview
Problem
Existing current measurement devices struggle with achieving a good signal-to-noise ratio (SNR) for very small input signals, leading to long conversion times and noise-induced varying digital values, which are not effectively addressed by prior art such as DE 10 2011 078 698 B3.
Innovation Solution
A device with dynamic adjustment of averaging and oversampling rate (OSR) based on input signal magnitude, using an evaluation electronics that includes an analog-to-digital converter (ADC) and a timing unit to adapt sampling rates and filter characteristics for optimal noise suppression and conversion speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling by averaging over several cycles is used to reduce noise, then signal-to-noise ratio is improved, but conversion time increases
Solution Approach 1:
The patent applies dynamics by making the oversampling rate adjustable rather than fixed. The evaluation electronics dynamically adapt the number of averaging cycles based on the input signal amplitude: using higher oversampling rates for small signals to achieve good SNR, and lower oversampling rates for large signals to reduce conversion time. This resolves the contradiction by optimizing both SNR and conversion time according to actual measurement conditions.
2Measurement precision
If a high number of measurements are averaged for small input signals to achieve good SNR, then measurement accuracy is improved, but conversion time becomes very long
Solution Approach 1:
The patent changes the parameter of oversampling rate dynamically based on input signal amplitude. For small input signals, a high oversampling rate is applied to achieve good SNR and measurement accuracy. For large input signals, the oversampling rate is reduced to minimize conversion time. This parameter adaptation resolves the contradiction between measurement accuracy and conversion time.
3Measurement precision
If the sampling rate is increased for small input signals to suppress noise, then signal-to-noise ratio is improved, but the speed of the device decreases
Solution Approach 1:
The patent makes the sampling rate dynamic rather than fixed. The evaluation electronics adjust the sampling rate according to the input signal amplitude: using higher sampling rates for small signals to suppress noise and improve SNR, and lower sampling rates for large signals to maintain device speed. This dynamic adjustment resolves the contradiction between SNR and device speed.
Data Source
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AI summary
The invention relates to a device and an associated method for detecting an electrical current (ILTG) in a line. The device comprises a shunt resistor (113), a prefilter (120), an amplifier (130) an analog-digital converter (200) and an oversampling- and decimation-filter (300). The electrical current (ILTG) flows through the shunt resistor (113) such that a shunt resistor voltage (Us) drops. The prefilter (120) prefilters the shunt resistor voltage (Us) to form an amplifier input voltage (Ue). The amplifier (130) detects the amplifier input voltage (Ue)) and amplifies same to form an amplifier output signal (133). The analog-digital converter (200) samples the amplifier output signal (133) with a sampling rate and converts it into a decimation filter input signal (301). The oversampling- and decimation-filter (300) filters the decimation filter input signal (301) to form a decimation filter output signal (302). The device provides the decimation filter output signal (302) as a measurement value signal for at least one value of the electrical current (ILTG) in the line. The oversampling- and decimation-filter (300) filters the shunt resistor voltage (Us) to form an amplifier input voltage (Ue) according to a value of the amplifier output signal (133) as a timer input value.