BMS ECU Single-Line Relay Control via Modulated Pulse Signals
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Solution Overview
Problem
The existing battery management system (BMS) and electronic control unit (ECU) communication is disrupted when CAN communication fails, leading to loss of control over the relay, causing the battery system to enter a safe state and preventing normal vehicle operation due to blocked power supply.
Innovation Solution
A single-line half-duplex communication method using a modulated pulse signal with varying frequency and duty cycle is established between the BMS and ECU to maintain control over the relay, allowing for relay switching operations even in the absence of CAN communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CAN communication is used for BMS and ECU communication, then communication reliability is improved under normal conditions, but communication fails when CAN communication disruption occurs
Solution Approach 1:
The patent changes the communication parameter from CAN bus protocol to single-line modulated pulse signal protocol. The ECU transmits control instructions by modulating the frequency and duty cycle of pulse signals on a single communication line, allowing the BMS to detect these modulated signals and execute relay control operations even when CAN communication is disrupted
Solution Approach 2:
The patent introduces a single-line modulated pulse signal communication channel as an intermediary backup mechanism. This alternative communication path uses simple voltage level changes (high/low levels representing binary signals) modulated by frequency and duty cycle variations to transmit relay control instructions, serving as a mediator when the primary CAN communication channel fails
2Reliability
If BMS forcibly opens relay when CAN communication fails, then battery system safety is improved, but vehicle power supply is blocked
Solution Approach 1:
The patent implements a feedback mechanism where the BMS monitors the state of the communication line and the relay status. When modulated pulse signals are detected on the single communication line, the BMS understands that the ECU intends to control the relay, and accordingly adjusts the relay state to match the ECU's intent rather than forcibly opening it, thus maintaining both safety and operability
Solution Approach 2:
The patent makes the relay control dynamic by enabling the BMS to switch between different control modes: when CAN communication is available, normal CAN-based control is used; when CAN communication fails but single-line communication is detected, the BMS switches to responding to modulated pulse signals; this dynamic adaptation allows the system to maintain appropriate relay control under varying communication conditions
Data Source
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AI summary
An ECU may transmit a pulse signal with a modulated frequency and duty cycle to a BMS so as to instruct a switching operation of a control target relay from among a plurality of relays. The BMS may control a switching operation of the corresponding relay according to the modulating pulse signal received from the ECU. The BMS may control a first voltage change period to the communication line and may transmit the same to the ECU as feedback so as to instruct a switching result of the corresponding relay according to the modulating pulse signal.