Industrial Control System EMI Correction via Switching Prediction
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Solution Overview
Problem
Electromagnetic disturbances caused by switching components in power electronics distort measured values in industrial control systems, particularly affecting programmable logic controllers due to proximity and wiring, leading to measurement errors.
Innovation Solution
A method involving prediction of switching on and off processes and operating states, combined with a neural network learning process, is used to correct measured values by determining and compensating for electromagnetic interference. This includes a digital filter to stabilize measurements and optimize filter time for minimal interference and maximum data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching components (converters, motors) are activated to perform industrial operations, then productivity and functional capability are improved, but electromagnetic interference is generated that corrupts analog input measurements
Solution Approach 1:
The system predicts switching events from the sequence program before they occur, allowing pre-computation of correction values. The prediction device analyzes the sequence program to determine when switching components will be activated, and the correction device prepares compensation values in advance to counteract the expected electromagnetic interference on analog inputs.
Solution Approach 2:
The system takes the harmful electromagnetic interference generated by switching components and converts it into a predictable, correctable phenomenon. By analyzing the relationship between switching events and interference patterns, the system computes correction values that transform the harmful interference into a manageable parameter that can be compensated for mathematically.
2Reliability
If digital filters are applied to stabilize measured values against interference, then measurement reliability is improved, but response time and data rate decrease
Solution Approach 1:
The system dynamically adjusts filter parameters based on the predicted switching events. Instead of using fixed heavy filtering that always reduces data rate, the filter strength and characteristics are modified according to the timing and nature of upcoming switching operations, maintaining reliability when needed while preserving response speed during normal operation.
Solution Approach 2:
The filtering approach transitions from static to dynamic by adapting filter characteristics in real-time based on the sequence program analysis. The system switches between different filtering modes or adjusts filter coefficients according to the operational state and predicted interference levels, optimizing the balance between stability and response time.
3Measurement precision
If correction values are computed and applied to measured values, then measurement accuracy is improved, but system complexity and computational load increase
Solution Approach 1:
The prediction device serves multiple functions: it analyzes the sequence program, predicts switching events, determines interference characteristics, and generates correction values. By consolidating these functions into a single multi-functional module, the system reduces overall complexity compared to having separate dedicated components for each function.
Solution Approach 2:
The system uses its own sequence program as the source for predicting interference events, making the correction mechanism self-contained and autonomous. The prediction device extracts information from the existing control logic without requiring external sensors or additional measurement infrastructure, reducing system complexity.
Data Source
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AI summary
The invention relates to a method for operating an industrial control system (1) comprising an automation controller (CPU) with a sequence program (OB1), a control means (2) configured for controlling a switching component (SR) of the power electronics and an input assembly (EA), wherein electromagnetic interference (EMI) occurs due to switching on and off processes (EV,AV) of the switching component (SR), which distorts a measured value (MW) acquired via the input assembly (EA), wherein a temporal occurrence of the switching on and off processes (EV,AV) and/or an operating state (BZ) is predicted for the switching component (SR), wherein the prediction is used to perform a correction of the measured value (MW) at a prediction time or during a prediction time range (VZB) with respect to the distortion caused by the electromagnetic interference (EMI).