Broadband Isolation Coupling Using Split-Frequency Transformer Paths
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Solution Overview
Problem
Current methods for coupling broadband signals galvanically, such as using optocouplers and transformers, are limited by low bandwidth, high offset errors, and low signal-to-noise ratios, and require synchronous modulation and demodulation, which are prone to time delays and phase errors.
Innovation Solution
The solution involves using two isolated transformers to separate and transform high and low frequency signal parts, where the low frequency signal is modulated with a rectangle or sinusoidal signal at a frequency lower than the transformer bandwidth, and employing a sample-hold device and low pass filters to compensate for time delays and improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocouplers and transformers are used for galvanic separation, then signal isolation is achieved, but bandwidth is limited and signal-to-noise ratio is low
Solution Approach 1:
The patent divides the broadband signal into multiple frequency bands (e.g., low frequency band below 500 kHz and high frequency band above 500 kHz) that are then transmitted through separate coupling channels (optocoupler and transformer respectively). This segmentation allows each component to operate within its optimal bandwidth range, achieving complete broadband signal transmission with high signal-to-noise ratio while maintaining galvanic isolation.
2Reliability
If signal is modulated with double the highest frequency component, then complete signal transformation through single transformer is achieved, but bandwidth utilization is wasted
Solution Approach 1:
Instead of modulating the entire signal and transmitting through a single transformer, the patent segments the signal into frequency bands and transmits them through different coupling mechanisms. The low frequency band is transmitted directly through an optocoupler while the high frequency band is modulated and transmitted through a transformer, optimizing bandwidth utilization for each channel.
Solution Approach 2:
The patent changes the transmission parameters by using different modulation strategies for different frequency bands. The low frequency band uses direct transmission through optocoupler without modulation, while the high frequency band uses modulation suitable for transformer coupling, thereby optimizing the use of available bandwidth in each channel.
3Reliability
If high frequency components are transformed through single transformer, then signal isolation is achieved, but transformation factor varies and ripple increases
Solution Approach 1:
The patent segments the frequency spectrum into bands that are transmitted through different coupling channels. By separating low frequency and high frequency components into different transmission paths (optocoupler and transformer), the system avoids the transformation factor variations and ripple issues that occur when all frequencies are transmitted through a single transformer.
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
This approach achieves a high signal-to-noise ratio and maximizes bandwidth while reducing the impact of time delays and phase errors, resulting in an efficient and accurate galvanic isolation coupling method.
Implementation Method 1
transforming a signal derived from the high frequency partial signal using a first isolating transformer
Implementation Method 2
modulating the low frequency partial signal with a modulation signal resulting in a modulated low frequency partial signal
Implementation Method 3
transforming a signal derived from the modulated low frequency partial signal using a second isolating transformer
Implementation Method 4
The input signal may be filtered using a low pass
Data Source
AI summary
An isolation coupler comprises a frequency splitter (36) for splitting an input signal (1) into a low frequency partial signal (2) and a high frequency partial signal (4) and a first isolating transformer (33) for transforming a signal derived from the high frequency partial signal (4) in a transformed high frequency partial signal (5). Moreover it may include a modulator (21) for modulating the low frequency partial signal (2) with a modulation signal (6) resulting in a modulated low frequency partial signal (7) and a second isolating transformer (34) for transforming a signal derived from the modulated low frequency partial signal (7) in a transformed low frequency partial signal (8).