Digital Integration Circuit Breaker Current Measurement
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Solution Overview
Problem
Analog integration circuits in low-voltage circuit breakers suffer from temperature drift and phase errors, leading to inaccurate measurement of current and active power due to their frequency-dependent phase shift and signal waveform distortion.
Innovation Solution
Implementing digital integration with an upstream filter in circuit breakers, specifically using a two-stage digital integrator with filters such as low-pass, high-pass, or infinite impulse response filters, to replace analog integration, thereby avoiding temperature drift and phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog integration circuits are used in circuit breakers, then the measurement of current and active power can be performed, but temperature drift and phase errors occur leading to measurement inaccuracy
Solution Approach 1:
The patent replaces the analog integration circuit (electrical/mechanical system) with a digital integration system. The Rogowski transducer output is fed into a digital signal processor that performs digital integration and filtering operations, eliminating the temperature-dependent analog components while maintaining the integration function necessary for accurate current and active power measurement.
2Measurement precision
If analog integration circuits are used, then current measurement is possible, but frequency-dependent phase shift distorts the signal waveform
Solution Approach 1:
The patent substitutes the analog integration circuit with a digital signal processing system that performs integration and filtering operations in the digital domain. This allows for precise control of the filtering characteristics and eliminates the frequency-dependent phase shift inherent in analog RC circuits, thereby preserving signal waveform accuracy while maintaining current measurement capability.
3Measurement precision
If calibration with tight tolerance components is used to reduce temperature drift, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent eliminates the need for precision analog integration circuits and their associated calibration requirements by transitioning to a digital integration system. The digital signal processor implements the integration function through software algorithms, removing the temperature-sensitive analog components and their tight tolerance requirements, thereby simplifying the device while maintaining or improving measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate determination of current and correct calculation of active power, enhancing power management applications by eliminating temperature dependences and phase errors.
Implementation Method 1
Rogowski transducers (air coil without an iron core) have the advantage of a very large current and frequency measurement range
Implementation Method 2
digital integration with an upstream filter is carried out in a circuit breaker
Data Source
AI summary
A circuit breaker for a low-voltage circuit is disclosed. In an embodiment, the circuit breaker includes a current conductor, assigned a measuring transducer for measuring the electrical current of the current conductor; a first filter connected to the measuring transducer; an analog/digital converter connected to the first filter; a second, high-pass filter connected to the analog/digital converter; and a digital integrator, connected to the high-pass filter and configured to determine the electrical current of the current conductor.