Construction Machine Charging Modes for Battery Life Control
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Solution Overview
Problem
Construction machines with built-in lithium-ion batteries face accelerated deterioration due to insufficient control of charging during work when using both external and battery power sources.
Innovation Solution
A construction machine with a power supply device, battery, and electric motor, controlled by a control device that operates in multiple modes to manage battery charging and discharging, setting upper limits on the state of charge to prevent overcharging and undercharging, including a battery drive mode, drive chargeable mode, and charge-only mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery is charged using external power source during work, then the machine can operate continuously with combined power sources, but the battery may be deteriorated due to insufficient control of charging
Solution Approach 1:
The control device dynamically adjusts the upper limit value of state of charge based on the operating mode. In charge-only mode, the upper limit is set to a higher value (e.g., 90-100%) to maximize battery charging when external power is available and machine is not operating. In drive chargeable mode, the upper limit is set to a lower value (e.g., 70-85%) to prevent battery deterioration during combined operation, thus resolving the contradiction between continuous operation capability and battery durability.
2Reliability
If the upper limit of state of charge is set high, then the battery can be fully charged and stored optimally, but the battery deteriorates when charged during work operation
Solution Approach 1:
The system transitions from a static charge limit approach to a dynamic one where the upper limit of state of charge is not fixed but changes according to the operating mode. The control device switches between different upper limit values based on whether the machine is in battery drive mode, drive chargeable mode, or charge-only mode, thereby adapting the charging strategy to current operational requirements and preventing battery deterioration during work while maintaining optimal storage conditions when applicable.
3Use of energy by moving object
If the battery is charged to high state of charge during work, then more energy is available for subsequent operation, but the charging control is insufficient and accelerates battery deterioration
Solution Approach 1:
The control device modifies the state of charge upper limit parameter based on operating conditions. During drive chargeable mode, it sets a conservative upper limit (70-85%) that provides sufficient energy for operation while preventing the harmful effects of overcharging. This dynamic parameter adjustment ensures adequate energy availability during work without accelerating battery deterioration, resolving the contradiction between energy availability and battery life.
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 effectively suppresses battery deterioration by maintaining optimal charge levels, extending the battery's lifespan while ensuring continuous power supply to the electric motor.
Implementation Method 1
a battery that is so provided as to be capable of charging the first power
Implementation Method 2
an electric motor that is driven by at least one of the first power and second power which is discharged by the battery
Data Source
AI summary
An exemplary construction machine comprises a power supply device that is connected to an external power source and outputs first power, a battery provided to be chargeable with the first power, and an electric motor that is driven by the first power and/or second power discharged by the battery. The construction machine further comprises a control device that controls the construction machine in any of a plurality of modes including a drive chargeable mode in which the first power can be used for charging the battery while being used for driving the electric motor, and a charge-only mode in which the first power can be used only for charging the battery. In the case of the drive chargeable mode, the control device sets the upper limit value of the amount of charge of the battery lower than in the case of the charge-only mode.