Switchable Isolation Circuit for Bus Signal Attenuation
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Solution Overview
Problem
Transformer attenuation and efficiency constraints in 'passive' daisy chain bus configurations for battery management systems, particularly in automotive applications, lead to challenges in signal propagation and node count limitations.
Innovation Solution
A data communication circuit with switchable isolation transformers and logic circuitry that mitigates signal propagation by presenting high series impedance until each node is initialized, using differential bus communication and switchable isolation circuits to block signals until identification is assigned, then allowing propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transformers are used in passive daisy chain bus configurations for signal isolation, then electrical isolation and noise immunity are improved, but signal attenuation increases and bus length is limited
Solution Approach 1:
The patent applies dynamics by making the transformer coupling switchable rather than fixed. The isolation circuit includes a switch that can dynamically change the transformer from a decoupled state (high impedance, blocking signals) to a coupled state (low impedance, allowing signals). This dynamic switching resolves the contradiction by allowing the system to have electrical isolation when needed while permitting signal transmission when communication is required.
Solution Approach 2:
The patent changes the impedance parameter of the transformer coupling dynamically. By switching the transformer between coupled and decoupled states, the impedance presented to the bus line changes from low to high. This parameter change allows the system to control both signal attenuation and electrical isolation, resolving the technical contradiction between these two opposing requirements.
2Length of stationary object
If signal repeaters are used in active daisy chain configurations, then signal propagation over long distances is improved, but current consumption increases causing battery charge misbalance
Solution Approach 1:
The patent replaces static signal repeaters with dynamic switchable isolation circuits. Instead of continuously active repeaters that consume power, the system uses switches controlled by a master node that dynamically enable or disable transformer coupling based on communication needs. This eliminates continuous current consumption while still allowing long-distance signal propagation when required.
Solution Approach 2:
The master node performs addressing and identification of slave nodes without requiring continuous power consumption from repeaters. The system uses the switchable isolation circuits to enable the master node to address specific slaves, and the slaves respond only when addressed. This self-service approach eliminates the need for continuously powered repeaters, resolving the contradiction between bus length and current consumption.
3Measurement precision
If bus switches are used to physically cut the bus for node initialization, then node identification is improved, but signal propagation is blocked until initialization completes
Solution Approach 1:
The patent uses dynamic switching control to manage signal propagation during node initialization. The master node dynamically controls the switchable isolation circuits to block signals during the addressing phase (improving identification precision) and then enables signal propagation when communication is required (restoring productivity). This temporal separation resolves the contradiction between accurate node identification and continuous signal propagation.
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 controls signal propagation and identification in a 'passive' daisy chain, reducing attenuation and extending bus length and node count, enhancing the efficiency of battery management systems.
Implementation Method 1
a switchable isolation circuit (133) including a transformer (135) mitigating passage of signals on the bus line by preventing current circulation in a second winding (141) of the transformer
Data Source
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AI summary
Aspects of the present disclosure are directed to facilitating communications to respective circuit nodes in a manner that may also be useful for mitigating undesirable signal attenuation. As may be implemented in accordance with one or more embodiments, switchable isolation circuits, presented by at least one transformer and switch, are utilized to isolate adjacent data processing nodes on a bus in which each data processing node includes logic circuitry and processes signal therein. For each of the switchable isolation circuits, switching circuitry operates to mitigate communication propagation over the differential bus between adjacent data processing nodes, by switching the switchable isolation circuit for providing isolation. This approach may be utilized, for example, to assign sequential identification to daisy-chained circuit nodes upon start-up or reset, for use in addressing each node directly for further communication therewith.