Electric Work Vehicle Power-Limit Control for Return Travel
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Solution Overview
Problem
Electric work vehicles risk depleting their power supply during movement, necessitating cumbersome towing or charging arrangements, unlike internal combustion engine vehicles which can refuel on the spot.
Innovation Solution
An electric work vehicle with a controller that switches between first and second control modes based on power remaining, reducing power consumption in the second mode to ensure the vehicle reaches a charging location without depleting the power storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the driver forcibly continues work after being informed of the end time, then the work can be completed, but the power storage device may be depleted during movement requiring towing or charging arrangements
Solution Approach 1:
The controller performs preliminary action by detecting the remaining power amount before depletion occurs and proactively switching from first control to second control. This advance detection and control switching prevents power depletion during movement, ensuring the vehicle can reach charging location without towing arrangements.
Solution Approach 2:
The controller dynamically switches between first control and second control based on real-time power remaining detection. When power remaining exceeds the threshold, first control enables full work functionality; when power remaining falls to or below the threshold, second control reduces power consumption to preserve mobility. This dynamic adaptation resolves the contradiction between maintaining productivity and ensuring power reliability.
2Duration of action of moving object
If the controller switches to second control to reduce power consumption, then the vehicle can reach charging location, but the work output is reduced
Solution Approach 1:
The controller dynamically adjusts control mode based on power remaining levels. During adequate power conditions, first control maximizes work output. When power remaining approaches the threshold, the controller transitions to second control, dynamically reducing power consumption to prioritize travel capability. This dynamic switching resolves the contradiction between work output and travel duration.
Solution Approach 2:
The controller changes operational parameters by switching control modes. First control allows full motor power for work operations; second control reduces motor power parameters to conserve energy for travel. This parameter change enables the vehicle to extend travel distance to charging location when power becomes limited.
3Productivity
If the threshold is set low to allow more work, then productivity increases, but the risk of power depletion during movement increases
Solution Approach 1:
The controller implements feedback by continuously detecting power remaining and comparing it against the threshold. This feedback mechanism allows the controller to switch from first control to second control when power remaining reaches the threshold, preventing power depletion during movement while maximizing work duration within safe limits.
Solution Approach 2:
The threshold serves as a critical parameter that balances productivity and reliability. By setting the threshold at an appropriate level, the system changes control parameters (from first to second control) when power remaining reaches this value, ensuring work can be completed while maintaining sufficient power for safe return to charging location.
4Reliability
If the threshold is set high to ensure power for travel, then power reliability improves, but the available work time is reduced
Solution Approach 1:
The threshold parameter is optimized to balance work time and power reliability. When power remaining exceeds the threshold, first control enables full productivity. When power remaining reaches the threshold, the controller switches to second control, preserving power for travel. This parameter setting ensures both adequate work time and reliable power for movement.
Data Source
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AI summary
An electric work vehicle is provided with: a power storage device configured to store power; a motor configured to drive at least either a travel device or a work device by consuming the power stored in the power storage device; a remaining amount detector configured to detect a remaining amount of power suppliable by the power storage device; and a controller switchable between a first control for controlling driving of the motor in response to a remaining amount value indicative of the remaining amount being greater than a preset threshold, and a second control for controlling driving of the motor so that power consumption of the motor is smaller than in the first control in response to the remaining amount value being less than or equal to the threshold.