Vehicular Multiplex Bus Backup via DC Powerline Communication
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Solution Overview
Problem
Existing multiplex communication systems in vehicles lack effective redundancy to ensure critical data transmission during faults in the primary communication bus without requiring significant additional circuitry and software enhancements.
Innovation Solution
A bus transceiver system that utilizes a power line for backup communication by converting multiplex messages to single-ended signals when a fault is detected, using a subtractor and balanced signal generator to transmit messages over the DC power line, maintaining the same message frame format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bus redundancy using added physical components and software enhancements is implemented, then reliability of critical data transmission is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The power line communication interface is designed to serve dual purposes: normal power delivery and backup communication channel. The same physical power lines that supply DC power to electronic modules are also used to transmit communication signals during bus faults, eliminating the need for dedicated redundant communication hardware.
Solution Approach 2:
The system uses its own existing power distribution infrastructure to provide backup communication capabilities. Rather than requiring external redundant components, the power lines themselves are repurposed to carry communication signals when the primary CAN bus fails, making the system self-sufficient for redundancy.
2Reliability
If bus redundancy using added physical components and software enhancements is implemented, then reliability of critical data transmission is improved, but manufacturing cost increases
Solution Approach 1:
The power line communication interface is designed to serve dual purposes: normal power delivery and backup communication channel. The same physical power lines that supply DC power to electronic modules are also used to transmit communication signals during bus faults, eliminating the need for dedicated redundant communication hardware.
Solution Approach 2:
The invention uses inexpensive, readily available components such as capacitors, resistors, and standard operational amplifiers to implement the power line communication interface. These are common electronic components that can be easily sourced and integrated without requiring specialized or expensive redundant communication hardware.
3Reliability
If signal conversion circuitry is added to enable power line communication, then backup communication capability is improved, but device complexity increases
Solution Approach 1:
The differential-to-single-ended signal conversion function is extracted from the main CAN transceiver and implemented as a separate, dedicated operational amplifier circuit. This isolation simplifies the overall system architecture by clearly separating power delivery and communication functions, making the backup communication capability independent and easier to manage.
Solution Approach 2:
Capacitors are introduced as intermediary coupling elements between the CAN transceiver output and the power line. These capacitors block DC power while allowing AC communication signals to pass through, effectively mediating between the power delivery system and the communication signal path without requiring complex switching or isolation circuitry.
4Reliability
If fault detection and switch activation is implemented, then automatic failover to backup channel is improved, but device complexity increases
Solution Approach 1:
The fault detection and failover control functions are merged into the existing CAN controller unit. The controller monitors bus health and automatically activates the power line communication interface when a fault is detected, eliminating the need for separate fault detection hardware and reducing overall system complexity.
Solution Approach 2:
The power line communication interface components (capacitors, resistors, operational amplifiers) are pre-configured and physically in place but remain inactive during normal operation. When a bus fault occurs, the controller simply needs to activate these pre-positioned components, enabling rapid failover without requiring complex real-time configuration or reconfiguration of the backup channel.
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
Ensures reliable transmission of critical data by diverting messages via the power line during bus faults without adding extra circuitry or software, preserving existing message protocols and ensuring compatibility with standard CAN transceivers.
Implementation Method 1
A subtractor generates a single-ended difference signal according to a voltage difference between the pair of transceiver output terminals
Implementation Method 2
A balanced signal generator has a single input adapted to receive an alternating component of a voltage at the power input terminal. The balanced signal generator has a pair of balanced outputs providing a differential signal to the transceiver output terminals
Implementation Method 3
A first switch selectably couples the single-ended difference signal from the subtractor to the power input terminal when in a conductive state. A second switch selectably couples the single input of the balanced signal generator to the power input terminal when in a conductive state
Data Source
AI summary
Multiplex communication in a vehicle is provided by a multiplex bus using complementary signals, such as a CAN bus. Bus redundancy for providing a backup communication channel in the event of a fault on the primary multiplex bus is achieved using power line communications (e.g., sending data over the already available DC power line). The need for additional circuitry is minimized by preserving the same message protocols (e.g., framing), because only signal conversion, filtering, and switching functions are required in order to divert messages via the power line.