Electric Excavator Battery Segmentation for Charging Availability
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Solution Overview
Problem
Electrically-operated hydraulic excavators face difficulties in charging due to the simultaneous exhaustion of all batteries, making it challenging to travel to a charging site or continue operation without knowledge of the operator.
Innovation Solution
The implementation of a battery management system that allows for the parallel connection of multiple battery systems, with automatic or manual switching to ensure only one system supplies power at a time, including remaining battery power monitoring and motor stop control to prevent complete discharge, enabling continued operation and awareness of battery exhaustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If all batteries are series-connected to supply electrical power to the electric motor, then the power output is sufficient for operation, but all batteries are simultaneously exhausted making it difficult to achieve charging
Solution Approach 1:
The battery device is divided into multiple independent battery systems (first battery system and second battery system), each capable of independently supplying power to the electric motor. This segmentation allows one system to be used while the other is charged, preventing complete exhaustion and ensuring charging availability.
2Reliability
If multiple battery systems are parallel-connected to allow switching, then charging availability is improved, but the device complexity increases
Solution Approach 1:
The battery system employs dynamic switching capability where the connection configuration can change based on operational needs. The switching mechanism allows transition between series-connection mode (for high power) and parallel-connection mode (for charging availability), optimizing performance while managing complexity through controlled adaptability.
3Productivity
If automatic switching between battery systems is implemented, then operational continuity is maintained, but the control system complexity increases
Solution Approach 1:
The control system incorporates feedback mechanisms that monitor the state of charge and operational status of each battery system. Based on this feedback, the system automatically determines when switching between battery systems is necessary, maintaining operational continuity without requiring complex manual intervention or overly sophisticated control algorithms.
Data Source
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AI summary
Provided is an electric construction machine capable of avoiding a situation where charging is difficult to achieve due to the exhaustion of a battery device. An electrically-operated hydraulic excavator includes an electric motor 31, a hydraulic pump 33 that is driven by the electric motor 31, hydraulic actuators 13A, 13B, 19 to 21 that are driven by hydraulic fluid discharged from the hydraulic pump 33, and a battery device 7 that serves as an electrical power source for the electric motor 31. The battery device 7 includes battery systems 56A, 56B that each have a plurality of batteries 55. A selector switch 28 makes it possible to select either one of the battery systems 56A, 56B. An arithmetic control section 53 of an inverter device 32 controls connection change switches 58A, 58B through battery controllers 54A, 54B to change the connections of the battery systems 56A, 56B so that electrical power is supplied to the electric motor 31 from either the battery system 56A or the battery system 56B, whichever is selected by the selector switch 28.