Galvanic Isolated Circuit Using Inductive Coupling for Signal Integrity
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Solution Overview
Problem
Galvanic isolated communication is necessary for charge balancing systems in electric and hybrid vehicles to ensure accurate charge balancing across battery packs, but existing technologies lack efficient methods for transmitting digital signals across voltage isolation barriers while being immune to current surges and stray magnetic fields.
Innovation Solution
An electric circuit arrangement using a transformer for inductive coupling between a transmitter and receiver circuit, employing pulse width modulation and differential coil structures to transmit digital signals, providing immunity to current surges and stray magnetic fields through current-based coding and magnetic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolated communication is implemented using traditional transformers, then voltage isolation is achieved, but the system becomes vulnerable to current surges and stray magnetic fields
Solution Approach 1:
The patent introduces an optical intermediary (light) between the transmitter and receiver circuits. The transmitter converts electrical signals to optical signals via an LED, which then couple magnetically to a transformer, and the receiver converts the transformed optical signals back to electrical signals. This optical intermediary isolates the circuits from direct electrical coupling, protecting them from current surges and stray magnetic fields while maintaining communication reliability.
Solution Approach 2:
The patent replaces the traditional direct electrical/transformer coupling with an optical-based transmission system. By substituting electrical signal transmission with optical signal transmission through an LED, the system eliminates the direct electrical pathway that would be susceptible to current surges and magnetic field interference, thereby improving reliability without the harmful vulnerabilities.
2Adaptability or versatility
If digital signals are transmitted across voltage isolation barriers, then communication between different voltage domains is enabled, but signal integrity is compromised by noise and interference
Solution Approach 1:
The patent uses light as an intermediary carrier to transmit digital signals across the voltage isolation barrier. The LED converts electrical digital signals to optical signals, which then couple to the transformer and are converted back to electrical signals on the other side. This optical mediation preserves signal integrity by eliminating direct electrical coupling that would introduce noise and interference, while enabling communication between different voltage domains.
Solution Approach 2:
The patent employs periodic pulse width modulation (PWM) signals for digital communication. The detection circuit generates PWM signals with specific duty cycles that correspond to digital logic levels. This periodic action provides robust noise immunity because the timing-based PWM encoding can tolerate signal amplitude variations and interference, maintaining signal integrity across the voltage isolation barrier.
3Productivity
If charge balancing control is implemented with full communication capability, then battery pack performance is optimized, but device complexity increases
Solution Approach 1:
The patent implements a multi-functional communication system where a single integrated circuit performs multiple functions: detection of battery cell charge conditions, generation of PWM control signals, and galvanic isolated communication with the charging circuit. The transmitter circuit is coupled to multiple battery packs and can communicate with a single receiver, enabling one communication channel to serve multiple charge balancing functions, thereby optimizing battery pack performance without proportionally increasing complexity.
Solution Approach 2:
The patent combines the detection circuit, PWM generation circuit, and communication transmitter into an integrated transmitter device. Similarly, the receiver circuit integrates signal reception, decoding, and control signal generation. This merging of functions into integrated circuits reduces the overall system complexity while maintaining full charge balancing capability, as the integrated devices can manage multiple battery packs through a single communication interface.
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 efficient transmission of digital signals across voltage isolation barriers, ensuring accurate charge balancing and extended battery life by immune to current surges and stray magnetic fields, thus enhancing the communication and control of battery packs in electric and hybrid vehicles.
Implementation Method 1
a transformer for inductive coupling the output side of the transmitter circuit to the input side of the receiver circuit
Data Source
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AI summary
An electric circuit arrangement for galvanic isolated communication comprises a transmitter circuit (120) having an input side (E120) for applying a digital signal (PWM) and an output side (A120) for generating an output signal (AS) in dependence on the digital signal (PWM). The circuit arrangement further comprises a receiver circuit (220) having an input side (E220) for receiving an input signal (ES) and having an output side (A220) for generating a reconstructed digital signal (PWM') in dependence on the input signal (ES), and a transformer (210) for inductive coupling the output side (A120) of the transmitter circuit (120) to the input side (E220) of the receiver circuit (220).