Galvanic Isolation Circuit Using Modulated Carrier Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrical circuits face challenges in communicating measurements across galvanically isolated power domains within electronic devices, such as power supplies or inverters, where different voltage supplies prevent direct current flow and require isolated measurement solutions.
Innovation Solution
An electrical circuit design featuring a transmitter in one power domain generating a modulated carrier signal using an oscillator and analog modulator, and a receiver in another power domain with a demodulator, utilizing galvanically isolated couplers like transformers or capacitors for inductive or capacitive coupling to transmit the signal across domains, allowing for accurate measurement transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is used between power domains, then safety and electrical isolation are improved, but current flow and signal transmission are blocked
Solution Approach 1:
The patent uses a capacitor as an intermediary element to couple signals between galvanically isolated power domains. The capacitor allows AC signal transmission while blocking DC current flow, thus maintaining galvanic isolation while enabling measurement signal transfer between domains with different voltage references
Solution Approach 2:
The patent replaces direct electrical connection (conductive coupling) with capacitive coupling to achieve signal transmission across galvanically isolated boundaries. This substitution allows measurement signals to be transferred without establishing a direct current path between power domains
2Device complexity
If direct connection between power domains is used, then signal transmission is simplified, but voltage reference differences cause measurement errors
Solution Approach 1:
The capacitor acts as a mediator that couples the measurement signal from the first power domain to the second power domain without requiring voltage reference alignment. This allows accurate measurement transfer even when power domains operate at different voltage levels and references
Solution Approach 2:
The patent segments the measurement system into isolated power domains with independent voltage references, connected through capacitive coupling. This segmentation allows each domain to operate independently while still enabling measurement signal transfer through the capacitor interface
3Reliability
If galvanic isolation is implemented, then safety is improved, but no return path exists for current flow
Solution Approach 1:
The capacitor provides a return path for AC measurement currents between galvanically isolated power domains without creating a direct DC current path. This allows measurement signals to complete their circuit while maintaining galvanic isolation and safety
Solution Approach 2:
The patent changes the operating parameters of the coupling element to allow AC signal passage while blocking DC current. The capacitor's frequency-dependent impedance allows measurement signals at specific frequencies to pass while blocking DC, thus enabling current flow for measurements while maintaining safety isolation
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
Enables reliable and accurate communication of sensor measurements across isolated power domains, reducing distortion and improving measurement resolution by using modulated carrier signals and appropriate coupling methods, facilitating control and monitoring within electronic devices.
Implementation Method 1
The pair of galvanically isolated elements may be inductively coupled together
Implementation Method 2
Alternatively, the pair of galvanically isolated elements may be capacitively coupled together
Data Source
AI summary
An electrical circuit and method includes a transmitter in a first power domain with a first supply voltage referenced to a first voltage reference. The transmitter has an oscillator generating a first carrier signal, and an analog modulator receiving an input sensor signal and the first carrier signal and generating a modulated carrier signal. A receiver is in a second power domain with a second supply voltage referenced to a second voltage reference. The second voltage reference is different from the first voltage reference. The receiver includes a demodulator that receives and demodulates the modulated carrier signal and generates an output sensor signal. At least one coupler includes a pair of galvanically isolated elements with one galvanically isolated element in each of the first and second power domains. The modulated carrier signal couples from the first power domain to the second power domain through the at least one coupler.