Galvanic Isolation Circuit With AC Short Capacitor for EMI Filtering
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Solution Overview
Problem
Existing galvanic isolation circuits for battery management systems in communication interfaces face challenges with high complexity and component requirements due to electromagnetic interference (EMI), which increases costs and complexity, and demands high voltage tolerance from transceivers, limiting performance and efficiency.
Innovation Solution
A galvanic isolation circuit with an AC short capacitor connected between reference terminals, reducing the need for complex EMI filter circuitry and lowering voltage tolerance requirements by providing a low impedance path for EMI currents, thereby simplifying the design and reducing component counts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex EMI filter circuitry is used to provide sufficient EMI filtering, then electromagnetic interference protection is improved, but device complexity and component requirements increase
Solution Approach 1:
The patent extracts the essential EMI filtering function from complex multi-component filter circuits and implements it through a simplified capacitive coupling approach with a single capacitor and resistors, maintaining EMI protection while reducing circuit complexity
Solution Approach 2:
The patent changes the filtering mechanism from inductive/capacitive LCR circuits to a simplified RC (resistor-capacitor) network, altering the circuit parameters to achieve comparable EMI filtering with fewer components and lower complexity
2Object-affected harmful factors
If high voltage tolerance transceivers are used to handle EMI currents, then EMI immunity is improved, but device cost and complexity increase
Solution Approach 1:
The patent introduces a capacitor and resistor network as intermediary elements between the transceivers and the communication lines, which absorb and shunt EMI currents away from the transceivers, allowing the use of lower voltage tolerance transceivers while maintaining EMI immunity
Solution Approach 2:
The patent converts potentially harmful EMI currents into beneficial filtering action by directing them through the capacitor-resistor network, where they are shunted to ground or dissipated, protecting the transceivers without requiring high voltage tolerance
3Object-affected harmful factors
If multiple capacitors and EMI filter components are used, then EMI filtering performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the core EMI filtering capability from expensive multi-component filter assemblies and implements it using a minimal set of inexpensive capacitor and resistor components, maintaining filtering performance while significantly reducing manufacturing cost
Solution Approach 2:
The patent replaces expensive, complex EMI filter components with inexpensive, readily available capacitor and resistor parts that can be easily manufactured and replaced, achieving comparable EMI filtering performance at lower cost
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 proposed solution effectively reduces the complexity and cost of EMI filter circuitry, lowers voltage tolerance requirements for transceivers, and enhances communication interface performance by providing sufficient EMI filtering without excessive component usage, enabling high-speed communication and improved immunity to electromagnetic disturbances.
Implementation Method 1
an AC short capacitor connected between the first reference terminal and the second reference terminal
Implementation Method 2
a galvanic isolator having a first side and a second side; a first communication link connected to the first side of the galvanic isolator and connectable to a first transceiver; a second communication link connected to the second side of the galvanic isolator and connectable to a second transceiver
Data Source
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AI summary
A galvanic isolation circuit (518) comprising: a galvanic isolator (534) having a first side and a second side; a first communication link (536) connected to the first side of the galvanic isolator and connectable to a first transceiver (514); a second communication link (538) connected to the second side of the galvanic isolator and connectable to a second transceiver (516); a first reference terminal (520-1) connectable to the first transceiver (514); a second reference terminal (520-2) connectable to the second transceiver (516); and an AC short capacitor (566) connected between the first reference terminal (520-1) and the second reference terminal (520-2).