Bidirectional Bus Switch Segmentation for Harsh Automotive Noise
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Solution Overview
Problem
Existing communication buses, such as the CAN bus, face challenges in harsh environments like automotive systems due to high costs, complex protocols, and poor performance in conditions like temperature, humidity, and vibration, necessitating a more robust and cost-effective solution.
Innovation Solution
A bidirectional bus system with switches and charge pumps that allow for selective coupling and decoupling of bus segments, using differential voltage signaling and optoisolators for galvanic isolation, enabling efficient communication over a two-wire interface while maintaining low impedance and noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing communication buses like CAN bus are used, then communication functionality is provided, but cost increases and protocol complexity increases
Solution Approach 1:
The bus system is segmented into multiple segments separated by switches. Each segment can be independently controlled and coupled to the main bus through switch elements, allowing modular expansion and simplified protocol implementation while maintaining reliable communication.
Solution Approach 2:
The bus configuration is made dynamic through switches that can be opened or closed based on communication needs. This allows the system to adapt the number of active segments and their connections in real-time, simplifying the protocol by enabling only necessary communications rather than requiring complex predefined protocols for all possible configurations.
2Reliability
If existing communication buses like CAN bus are used, then communication functionality is provided, but cost increases
Solution Approach 1:
The patent uses simple, inexpensive switch elements and basic transceiver circuits instead of expensive dedicated CAN bus controllers. The switches can be standard automotive switches or even simpler semiconductor switches, dramatically reducing component cost while maintaining communication reliability through the modular segment architecture.
Solution Approach 2:
The bus system uses universal components like standard switches, resistors, and basic transceivers that can be manufactured at low cost. The same simple hardware architecture supports multiple communication scenarios (single segment, multiple segments, master-slave configurations) without requiring expensive specialized components for each mode.
3Reliability
If existing communication buses are used, then communication is provided, but performance deteriorates in harsh environments
Solution Approach 1:
Dividing the bus into isolated segments with switches between them reduces the impact of environmental interference on the entire system. If one segment experiences electromagnetic interference or voltage spikes due to harsh conditions, only that segment is affected, while other segments continue to communicate reliably through the isolated switch connections.
Solution Approach 2:
The switch elements act as intermediaries between segments and the main bus, providing galvanic isolation and protecting the communication system from environmental harmful factors like voltage spikes, electromagnetic interference, and ground loops that commonly affect automotive communication buses in harsh environments.
4Adaptability or versatility
If switches are opened to decouple segments, then bus segmentation is achieved, but communication path is interrupted
Solution Approach 1:
The switches provide dynamic reconfigurability, allowing the bus to transition between different topologies (single segment, multiple segments, various connection configurations) based on communication needs. The system can quickly close switches to restore communication paths when segments need to be connected, maintaining reliability while providing versatility.
Solution Approach 2:
The system can pre-establish switch configurations before communication begins, ensuring that necessary communication paths are already in place. Switches can be closed in advance to connect segments that need to communicate, avoiding interruptions during actual data transmission while still allowing flexible reconfiguration when needed.
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
The solution provides a low-cost, reliable, and noise-immune bidirectional communication system capable of operating in harsh conditions, supporting high-frequency communication and maintaining stability with multiple bus slaves, even under varying voltage conditions.
Implementation Method 1
a charge pump configured to couple to the bidirectional bus and to provide electrical power to the switch control
Implementation Method 2
using differential voltage signaling and optoisolators for galvanic isolation
Implementation Method 3
using differential voltage signaling and optoisolators for galvanic isolation, enabling efficient communication over a two-wire interface while maintaining low impedance and noise immunity
Data Source
AI summary
A bidirectional bus system is provided. The bidirectional bus system includes a plurality of bus slaves configured to couple to a bidirectional bus. Each bus slave of the plurality of bus slaves has a switch operated by a switch control to selectably couple and decouple an upstream portion and a downstream portion of the bidirectional bus relative to the bus slave, with the switch control being powered by activity on the bidirectional bus. A method of operating a bus is also provided.