Excavator Power Supply Switching for Drive Power and Continuity
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Solution Overview
Problem
Existing electric work machines face challenges in providing sufficient drive power when relying solely on commercial power supplies for high-demand tasks and suffer from operational disruptions when battery abnormalities occur or when the battery's state of charge reaches a critical level.
Innovation Solution
An electric work machine system that includes a power supply converter, a battery, an inverter, and relays to switch between power sources, allowing the electric motor to be driven by either an external power supply, the battery, or both, and enabling charging modes to extend battery life and ensure continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor is driven only with electric power from the commercial power supply, then the system is simple to operate, but sufficient drive power cannot be obtained in cases of work requiring high drive power
Solution Approach 1:
The patent combines multiple power sources (commercial power supply and battery) into a unified power supply system. The power supply switching device merges the electrical circuits from both power sources, allowing the system to access the high drive power of the battery when needed while maintaining the operational simplicity of commercial power supply for normal tasks.
2Power
If the electric motor is driven by the battery only, then sufficient drive power is available, but the work cannot be continued when the state of charge reaches a lower limit value
Solution Approach 1:
The power supply system is designed with multi-functionality to handle different operating conditions. The power supply switching device can switch between battery-only mode for high power demands, commercial power supply mode for extended operation, and combined mode for optimal performance. This universality ensures continuous operation by providing alternative power sources when the battery state of charge reaches lower limits.
3Productivity
If the electric motor is driven while the battery is being charged by the external power supply, then the battery is utilized efficiently, but the work cannot be continued when abnormality occurs to the battery
Solution Approach 1:
The power supply switching device acts as an intermediary between the battery, commercial power supply, and inverter. It monitors the battery status and can switch to commercial power supply when battery abnormalities occur, ensuring operational continuity. The switching device mediates the power flow to maintain efficient battery utilization during normal charging operation while providing a safety net for abnormal conditions.
4Reliability
If multiple power sources and switching mechanisms are added to ensure continuous operation and sufficient power, then reliability and power capability are improved, but the device complexity increases
Solution Approach 1:
The power supply switching device is designed to automatically monitor power source status and perform switching operations based on pre-set conditions. This self-service capability reduces the need for complex manual control systems and minimizes the operational complexity for the user. The system automatically manages the complexity of multiple power sources and switching mechanisms, providing reliable continuous operation while keeping the user interface simple.
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 system allows for efficient power management, reducing battery usage and extending its lifespan, ensuring continuous operation even in abnormal battery states by switching between power sources, thereby addressing the limitations of existing technologies.
Implementation Method 1
a power supply that converts an alternating-current power supply voltage of an external power supply into a direct-current power supply voltage
Implementation Method 2
an inverter that converts the direct-current power supply voltage into the alternating-current power supply voltage
Implementation Method 3
a battery that charges or discharges electric power from the power supply
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An excavator 1 comprising: a power supply 61 that converts AC power supply voltage from a commercial power supply 5 into DC power supply voltage; a battery 62 that charges or discharges power from the power supply 61; an inverter 63 that converts DC power supply voltage to AC power supply voltage; an electric motor 7 that has power supplied thereto, and is controlled, by the inverter 63; a first electrical circuit 6a that supplies power to the inverter 63 from the power supply 61; a second electrical circuit 6b that joins from the battery 62 to the first electrical circuit 6a; an inverter relay 64 arranged between the inverter 63 and a junction point 6c between the first electrical circuit 6a and the second electrical circuit 6b; a battery relay 65 arranged between the junction point 6c and the battery 62; and a power supply relay 66 arranged between the junction point 6c and the power supply 61.