Galvanic Isolation Coupling Device with Variable Capacitance
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Solution Overview
Problem
Existing galvanic isolation coupling devices face limitations such as compromises between signal coupling, insulation, and parasitic capacitance, with magnetic transformers, capacitors, and opto-couplers having specific drawbacks like non-bidirectionality and low insulation, and piezoelectric transformers being expensive and offering low voltage withstand.
Innovation Solution
A galvanic isolation coupling device using a variable capacitance capacitor with four electrodes, where the capacitance is adjusted via electrostatic, electromagnetic, or piezoelectric actuation, allowing for bidirectional signal transmission while maintaining insulation between circuits, utilizing a four-electrode capacitor with insulating regions and control electrodes to vary capacitance in response to control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic transformers are used for galvanic isolation, then signal coupling is achieved, but parasitic capacitances between windings and compromise between isolation ratio and coupling coefficient must be made
Solution Approach 1:
The patent extracts the problematic parasitic capacitances by using a capacitor with electrodes electrically isolated from the main signal path. The variable capacitance element is connected to the signal but electrically isolated from direct galvanic connection, removing the harmful parasitic effects while maintaining the useful coupling function.
Solution Approach 2:
The patent introduces an intermediary variable capacitance element that couples the input and output circuits without direct galvanic connection. This intermediary capacitor, controlled by isolated control electrodes, mediates the signal transmission while maintaining electrical isolation and eliminating parasitic capacitance issues.
2Reliability
If coupling capacitors are used for galvanic isolation, then isolation is achieved, but compromise between signal transmission speed and common-mode immunity must be found
Solution Approach 1:
The patent employs a dynamic variable capacitance that can be adjusted in real-time. The capacitance value changes in response to the input signal, allowing the system to optimize between isolation and transmission speed dynamically. This dynamic adjustment eliminates the need for fixed compromises.
Solution Approach 2:
The patent changes the capacitance parameter dynamically using control signals applied to the variable capacitance element. By varying the capacitance value based on signal conditions, the system adapts to maintain both isolation integrity and transmission speed without compromise.
3Reliability
If optocouplers are used for galvanic isolation, then parasitic capacitances are eliminated, but bidirectional transmission capability is lost
Solution Approach 1:
The patent creates a universal coupling device that can transmit signals bidirectionally while maintaining galvanic isolation. The variable capacitance element responds to control signals regardless of direction, enabling the same structure to handle both input-to-output and output-to-input transmission effectively.
Solution Approach 2:
The patent inverts the traditional unidirectional optocoupler approach by using a bidirectional variable capacitance element. Instead of light-based unidirectional coupling, the system uses electrical field-based coupling that naturally supports bidirectional signal flow while maintaining isolation.
4Reliability
If piezoelectric transformers are used for galvanic isolation, then isolation is achieved, but cost increases and voltage withstand capacity is limited
Solution Approach 1:
The patent replaces expensive piezoelectric materials with standard capacitor structures that can achieve the same isolation function. The variable capacitance element uses conventional electrical components rather than costly piezoelectric ceramics, reducing cost while maintaining isolation performance.
Solution Approach 2:
The patent changes the isolation mechanism from piezoelectric voltage transformation to capacitive coupling with electrical field isolation. This parameter change allows for higher voltage withstand capacity by using insulating materials and结构设计 that are not limited by piezoelectric material breakdown voltages.
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 solution provides effective bidirectional galvanic isolation with improved insulation and reduced parasitic capacitance, enabling efficient signal transmission between circuits with different voltage levels, and is adaptable to various actuation mechanisms.
Implementation Method 1
a variable capacitance capacitor having first and second electrodes movable relative to each other, separated by an insulating region, and third and fourth electrodes electrically isolated from the first and second electrodes, adapted to receive a control signal to vary, by an electrostatic, electromagnetic or piezoelectric actuation mechanism, the relative position of the first and second electrodes, so as to vary the capacitance between the first and second electrodes
Implementation Method 2
a variable capacitance capacitor having first and second electrodes movable relative to each other, separated by an insulating region, and third and fourth electrodes electrically isolated from the first and second electrodes, adapted to receive a control signal to vary, by an electrostatic, electromagnetic or piezoelectric actuation mechanism, the relative position of the first and second electrodes, so as to vary the capacitance between the first and second electrodes
Implementation Method 3
a variable capacitance capacitor having first and second electrodes movable relative to each other, separated by an insulating region, and third and fourth electrodes electrically isolated from the first and second electrodes, adapted to receive a control signal to vary, by an electrostatic, electromagnetic or piezoelectric actuation mechanism, the relative position of the first and second electrodes, so as to vary the capacitance between the first and second electrodes
Data Source
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AI summary
The invention relates to a system comprising first and second electrical or electronic circuits galvanically isolated from each other, and a coupling device (400) connecting the first circuit to the second circuit, the coupling device comprising a variable capacitance capacitor (C) comprising first (S) and second (D) electrodes movable relative to each other, separated by an insulating region, and third (G) and fourth (R) electrodes electrically isolated from the first and second electrodes, adapted to receive a control signal (Ve) to vary, by an electrostatic, electromagnetic or piezoelectric actuation mechanism, the relative position of the first (S) and second (D) electrodes, so as to vary the capacitance (CSD) between the first (S) and second (D) electrodes.