Electric work machine
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Solution Overview
Problem
Existing electric work machines experience uncomfortable battery switching during motor startup due to immediate voltage drops, leading to frequent battery changes, which disrupts user experience.
Innovation Solution
Incorporating a controller with first and second thresholds to manage battery discharge and connection to the motor, ensuring stable battery usage by prioritizing battery selection based on voltage thresholds and user commands, thereby preventing immediate battery changes during motor startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single threshold is used to determine battery discharge status, then the battery switching logic is simple, but the battery may be switched immediately after motor startup causing user discomfort
Solution Approach 1:
The single threshold is segmented into two distinct thresholds: a first threshold for determining whether the battery can be discharged, and a second threshold (lower than the first) for determining whether to stop discharge. This segmentation prevents immediate battery switching after motor startup by requiring the voltage to drop below the second threshold before switching occurs, thereby resolving the contradiction between simple switching logic and user comfort.
2Ease of operation
If the battery switching threshold is set low to prevent frequent switching, then user comfort is improved, but the battery discharge capacity is reduced
Solution Approach 1:
The system dynamically adjusts the threshold based on motor operation state. During motor startup, the first threshold is used for initial discharge determination. Once the motor is running, the second (lower) threshold becomes active for discharge termination, allowing the battery to discharge closer to its capacity limit while preventing frequent switching during critical startup phases.
3Device complexity
If the first threshold is used for both startup and discharge termination, then the control logic is simple, but immediate battery switching occurs during startup reducing reliability
Solution Approach 1:
The system performs preliminary action by establishing the first threshold for initial discharge permission before motor startup. This preliminary threshold setting ensures that batteries with sufficient voltage can start the motor without risk of immediate switching. The second threshold is then applied for discharge termination, creating a buffer zone that prevents reliability issues during startup while maintaining simple control logic through the two-threshold framework.
Data Source
AI summary
An electric work machine includes a motor, a first connector, a second connector, an energizing circuit, a manual switch, and a controller. The controller electrically disconnects the first connector from the motor based on a first voltage value below a first threshold at a start of motor rotation. The controller maintains an electrical connection of the first connector to the motor based on the first voltage value below the first threshold and equal to or greater than a second threshold during discharge of the first battery.