Phase-Modulated Input Circuit for Galvanically Isolated Multi-Voltage Signals
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Solution Overview
Problem
Existing industrial controllers and measurement apparatuses face challenges in achieving electromagnetic compatibility, adapting to various voltage ranges, and integrating digital and analog inputs with galvanic isolation efficiently, while avoiding high costs and component diversity.
Innovation Solution
A phase modulation converter system with an amplitude modulator, adder, limiter, and demodulation facility, utilizing coupling capacitors for galvanic isolation and suppressing noise amplitude modulation, allowing for universal integration across different voltage ranges and channel configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocouplers are used for electrical isolation, then information transmission across isolation is achieved, but power loss increases and component complexity increases due to over-dimensioned current requirements
Solution Approach 1:
The patent replaces the optical transmission mechanism of optocouplers with a capacitive coupling mechanism. Instead of using LED-based optical transmission that requires over-dimensioned currents, the invention uses electrical capacitive coupling to transmit signals across the isolation barrier, thereby eliminating the excessive power consumption associated with optocoupler operation.
Solution Approach 2:
The patent changes the transmission parameter from current-based (optocoupler CTR dependent on LED current) to voltage-based capacitive coupling. By using voltage dividers and capacitive coupling, the system achieves reliable signal transmission without requiring the high currents that cause power loss in optocoupler systems.
2Adaptability or versatility
If different circuits are realized for various input voltage classes, then compatibility with different voltage ranges is achieved, but device complexity and component diversity increase
Solution Approach 1:
The patent implements a universal input circuit design that can handle multiple voltage classes (24VDC, 48VDC, 110VDC, 110/120/230VAC) through a single standardized circuit topology. The capacitive coupling and voltage divider network automatically adapt to different voltage levels without requiring separate dedicated circuits for each voltage class, thereby reducing component diversity while maintaining broad voltage compatibility.
3Object-affected harmful factors
If strong filtering is applied to achieve EM resistance, then electromagnetic compatibility is improved, but device complexity and cost increase due to additional capacitors
Solution Approach 1:
The patent converts the potentially harmful high-frequency noise into a beneficial filtering mechanism by using the inherent capacitance of the coupling capacitors. These capacitors naturally attenuate high-frequency common-mode noise without requiring additional filtering components, thereby achieving EM resistance while avoiding increased device complexity.
4Reliability
If capacitive or inductive data couplers are used for electrical isolation, then information transmission is achieved, but additional supply voltage requirements and component cost increase
Solution Approach 1:
The patent extracts and eliminates the need for separate supply voltage circuits by using the process signal itself to power the isolation barrier. The capacitive coupling allows the signal to be transmitted without requiring additional power rails or supply voltage generation circuits, thereby simplifying the overall system architecture while maintaining reliable information transmission across the isolation barrier.
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
The system provides efficient electromagnetic interference resistance, reduces component complexity and cost, and enables synchronized multi-channel input operations with diagnostic capabilities, enhancing integration and performance in industrial controllers and measurement apparatuses.
Implementation Method 1
The signal is coupled across the galvanic isolation barrier using coupling capacitors
Implementation Method 2
an amplitude modulator for modulating an amplitude of the input signal on a carrier
Implementation Method 3
a limiter for suppressing a noise amplitude modulation in the phase-modulated signal
Data Source
AI summary
An input facility for a controller or measurement apparatus includes at least one input circuit for providing at least one digital or at least one analog input for a controller or measurement apparatus, wherein the at least one input circuit includes at least one phase modulation converter that has an amplitude modulator with carrier suppression to which an input signal can be supplied on the input side in order to obtain a carrierless amplitude-modulated signal, an adder for adding a carrier signal shifted by 90° to the carrierless amplitude-modulated signal and for obtaining a phase-modulated signal, a limiter to which the phase-modulated signal is supplied and with which a noise amplitude modulation in the phase-modulated signal can be suppressed, and a demodulation facility to which the signal output from the limiter is supplied and that can be sampled therein with at least one sampling clock signal.