Isolation Barrier Power Transfer Dithering
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Solution Overview
Problem
Existing systems for transferring power across an isolation barrier often generate unwanted electrical interference, which can be problematic for nearby electronic components, and there is a need to effectively manage this interference while ensuring reliable power transfer between different voltage domains.
Innovation Solution
The system employs a dithering technique to modify the spectral distribution of the oscillating power signal by varying the oscillator frequency and control cycle, using a dither circuit with pseudo-random number generators to spread noise across a wider frequency range, thereby reducing interference and meeting electromagnetic interference emission standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power is transferred across an isolation barrier using conventional methods, then power transfer is achieved, but unwanted electrical interference is generated
Solution Approach 1:
The patent employs spread spectrum modulation techniques that modulate the power transfer signal with a pseudo-random code, spreading the spectral energy over a wide frequency range. This periodic modulation approach transforms concentrated interference at specific frequencies into distributed low-level interference across broader bands, reducing peak interference levels while maintaining power transfer functionality
Solution Approach 2:
The system dynamically adjusts modulation parameters including spreading code rate, frequency offset, and signal amplitude to optimize the balance between power transfer efficiency and interference reduction. By changing these parameters adaptively, the system can meet EMI Class B standards while ensuring reliable power delivery across the isolation barrier
2Object-affected harmful factors
If frequency spreading is used to suppress electromagnetic interference, then EMI is reduced, but system complexity increases
Solution Approach 1:
The patent introduces a spread spectrum modulator as an intermediary component between the power source and the isolation barrier. This modulator applies pseudo-random coding to the power signal, acting as a mediator that transforms the signal characteristics to reduce EMI. The intermediary approach allows conventional power transfer circuitry to be used while adding EMI mitigation functionality through signal processing
Solution Approach 2:
The system replaces complex hardware-based EMI filtering mechanisms with software-defined spread spectrum modulation techniques. Instead of using multiple passive filters and shields that would increase physical complexity, the patent uses digital signal processing and pseudo-random modulation to achieve EMI Class B compliance, substituting mechanical/electrical filtering with algorithmic signal transformation
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 effectively reduces noise interference for neighboring components, ensuring reliable power transfer and compliance with electromagnetic interference standards, such as EMI Class B for residential use.
Implementation Method 1
a transformer (6) having a primary winding (14) on the first side (10) of the isolation barrier (4) and a secondary winding (16) on the second side (12)
Data Source
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AI summary
It is often desirable to transmit data between circuits or components operating at a relatively high voltage and circuits operating at a relatively low voltage. Such a task can be performed by use of an isolator. Some isolator designs use magnetic coupling to transfer the data as this is more robust against inadvertently transmitting high voltage transients than capacitor based isolators. However it is often desirable to encode the data for exchange across the transformer of the isolator and decode after transmission across the transformer. This requires power for the encoding and decoding circuits. To ensure both sides are powered, power may be transferred by another transformer. The transformer primary is driven by an oscillating signal. The system disclosed in some embodiments herein varies the frequency of the oscillating signal to mitigate the risk of it interfering with other circuits or systems associated with the isolator.