Isolated Communication Bus for High-Voltage Ground Potential Differences
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Solution Overview
Problem
High-voltage ground potentials in systems with daisy-chained modules, such as photovoltaic farms and battery charging systems, pose a challenge for communication between a controller at 0V ground potential and modules at varying reference potentials, making effective communication difficult.
Innovation Solution
An isolated communication bus system with bus interfaces that include a primary interface unit, a secondary interface unit, and an isolator, allowing the primary unit to communicate with the master device at a common ground potential while the secondary unit is referenced to different ground potentials, using electrical isolation techniques like transformers to facilitate communication across varying voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If daisy-chained modules are used with series-coupled batteries to achieve high voltage output, then power output capability is improved, but ground potential difference between modules and controller increases making communication difficult
Solution Approach 1:
The patent introduces an isolated communication bus as an intermediary communication channel between the controller and daisy-chained modules. This bus includes separate signal lines for data transmission and reception that are electrically isolated from the high-voltage power lines, allowing communication without direct galvanic connection. The isolation barrier acts as a mediator that enables information exchange while preventing harmful voltage differences and electrical interference from affecting the communication process.
2Power
If modules are connected in series to increase voltage, then system voltage capability is improved, but electrical isolation between different ground potentials deteriorates
Solution Approach 1:
The communication system is segmented into electrically isolated domains. Each module has its own ground reference, and the isolated communication bus creates separate communication channels that do not share common ground paths. This segmentation prevents ground loops and electrical interference from propagating between modules with different ground potentials, maintaining electrical isolation reliability while allowing high-voltage series connection.
Solution Approach 2:
The isolated communication bus serves as an intermediary that bridges modules at different ground potentials without requiring a common reference. The bus includes transmission and reception lines that are galvanically isolated, allowing each module to communicate its status and receive control commands independently of the high-voltage power distribution network's ground references.
3Speed
If direct communication lines are used between controller and modules, then communication speed is improved, but electrical interference and noise from high voltage increases
Solution Approach 1:
The isolated communication bus introduces an electrical isolation barrier as a mediator between the low-voltage controller domain and high-voltage module domains. This isolation prevents high-voltage transients, noise, and electrical interference from coupling into the communication signal paths, while still allowing fast digital communication through dedicated isolated transmission and reception lines.
Solution Approach 2:
The patent replaces direct galvanic connection (mechanical electrical contact) with electromagnetic coupling through isolation barriers. Instead of using shared ground references and direct wire connections that are susceptible to interference, the system uses isolated communication channels that transmit signals through electromagnetic fields separated by electrical insulation, substituting the direct mechanical electrical connection with a non-contact electromagnetic 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 timely and effective communication between the master device and slave devices with different ground reference potentials, allowing for the collection and provision of information, and can be used with various communication protocols like SPI, I2C, and LIN.
Implementation Method 1
an isolator 114 electrically isolates the primary interface unit 110 from the secondary interface unit 112
Data Source
AI summary
A system includes a master device and multiple slave devices. The system also includes multiple bus interfaces forming a communication bus that couples the master and slave devices. Each bus interface includes a primary interface unit configured to communicate over first and second buses, where the first and second buses form a portion of the communication bus. Each bus interface also includes a secondary interface unit configured to communicate with the primary interface unit and to communicate with one of the slave devices over a third bus. Each bus interface further includes an isolator configured to electrically isolate the primary interface unit and the secondary interface unit. The primary interface unit is configured to receive multiple commands over the first bus, execute a first subset of commands, transmit a second subset of commands over the second bus, and transmit a third subset of commands over the third bus.