Working Vehicle DC Power Circuit with BMS-Gated Main Supply

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Solution Overview

Problem

In existing battery management systems (BMS) for working vehicles, direct current power is supplied only by a main power source, leading to safety risks when the main power source is in an abnormal state, as the BMS may not be activated, and there is a risk of fire due to unmonitored power supply.

Innovation Solution

A direct current power supply circuit is implemented with a secondary power source and relays controlled by the BMS to ensure safe activation and monitoring of the main power source before use, allowing the BMS to determine the main power source's readiness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If direct current power is supplied to the BMS only by the main power source, then the power supply structure is simple, but the safety is reduced when the main power source is in an abnormal state

Engineering Contradiction:
Improvepower supply structureVSAvoidsafety
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The power supply system is segmented into two independent power sources: a main power source for driving the drive unit and a sub power source for activating the BMS. This segmentation allows the BMS to be powered independently from the main power source, enabling safety monitoring even when the main power source is abnormal.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sub power source is activated in advance to power the BMS before the main power source is fully operational. This preliminary action ensures that the BMS can perform safety checks and monitoring functions immediately upon system startup, before any potential abnormalities in the main power source could cause harm.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If the main power source supplies direct current power to both the drive unit and the BMS, then the power supply structure is simple, but the BMS cannot be activated when the main power source is abnormal

Engineering Contradiction:
Improvepower supply configurationVSAvoidBMS activation
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The power supply configuration is segmented to provide separate power paths: the main power source connects to the drive unit, while the sub power source independently connects to the BMS. This ensures that BMS activation is not dependent on the main power source's operational status.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sub power source acts as an intermediary power supply that bridges the gap between system startup and main power source operational verification. It provides the necessary power to activate the BMS during the transition period when the main power source status is undetermined.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of time

If the main power source is used without BMS determination, then the system starts quickly, but the risk of fire increases due to unmonitored power supply

Engineering Contradiction:
Improvesystem startup timeVSAvoidfire risk
Core Design Contradiction:
Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The BMS is activated in advance by the sub power source to perform preliminary safety checks on the main power source before it begins supplying power to the drive unit. This preliminary action includes monitoring voltage, current, and temperature parameters to detect potential fire hazards.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The BMS continuously monitors the main power source's operational parameters and provides feedback control. When abnormalities are detected that could lead to fire risks, the BMS sends feedback signals to adjust or shut down the power supply, preventing harmful effects before they occur.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3708404B1Direct current power supply circuit mounted in working vehicle
Publication Date: 2025.11.12 TAKEUCHI MFG CO LTD
  • EP3708404B1 patent drawingFigure 1
  • EP3708404B1 patent drawingFigure 2
  • EP3708404B1 patent drawingFigure 3

AI summary

There is provided a direct current power supply circuit mounted in a working vehicle with increased safety as compared with related art by a configuration where a main power source is used after a battery management system (BMS) determines that the main power source can be used. A direct current power supply circuit (10) includes a first power source (11), a switch (13), a second power source (12) and a first relay (17), in which the first power source (11) is connected to a battery management system (4) through the first relay (17) so as to supply direct current power, the battery management system (4) is activated by supply of direct current power from the second power source (12) when the switch (13) is turned on, and the first relay (17) is on-controlled when determined that the first power source (11) can be used.