Electric Mowing Vehicle Adaptive Power Map for High-Load Mowing
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Solution Overview
Problem
In mowing vehicles with multiple electric motors, uneven mowing loads due to varying plant species and densities can cause some motors to suddenly stall, leading to unmown grass areas, which are difficult to detect due to low operating noise.
Innovation Solution
Implement a high-load-adaptive control system that adjusts the torque and rotation speed of mowing motors using a power map to balance loads, allowing early detection of high loads and preventing sudden stops, ensuring efficient mowing by adjusting vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mowing motor operates at high rotation speed to maintain productivity, then the mowing efficiency is improved, but the motor is more prone to sudden stoppage under high load conditions
Solution Approach 1:
The patent applies dynamics by making the power map adaptive rather than fixed. The controller dynamically switches between normal power map and high-load-adaptive power map based on detected motor load conditions. This allows the motor to operate at high rotation speeds during normal conditions for productivity, while automatically adjusting to prevent stall under high load, thus resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent changes the operational parameters (rotation speed and torque limits) based on load conditions. By defining a high-load-adaptive power map with modified boundary rotation speeds and torque limits, the system adjusts motor parameters to extend the time before stall occurs during high load, while maintaining high-speed operation during normal conditions, thereby balancing productivity and reliability.
2Device complexity
If the motor operates without load balancing control, then the device complexity is reduced, but the motor may suddenly stall under excessive load
Solution Approach 1:
The patent implements feedback control by continuously monitoring the load on each mowing motor and using this information to determine when to switch to the high-load-adaptive power map. This feedback mechanism enables the system to automatically respond to high load conditions and prevent stall, improving reliability without requiring complex predictive or adaptive algorithms, thus maintaining reasonable device complexity.
3Reliability
If the boundary rotation speed in the high-load-adaptive power map is set lower, then the motor is protected from sudden stoppage, but the mowing speed and productivity are reduced
Solution Approach 1:
The system dynamically adjusts the boundary rotation speed based on load conditions. During normal operation, the motor operates at high rotation speeds for productivity. When high load is detected, the system switches to the adaptive power map with lower boundary rotation speeds to prevent stall. This dynamic adjustment resolves the contradiction by allowing high speed when safe and reducing speed only when necessary for protection.
Data Source
AI summary
[Problem] To provide a mowing vehicle capable of efficiently carrying out mowing work by suppressing the grass from being left unmown in an early stage even when a high load acts on a mowing motor. [Solution] The mowing vehicle includes a mowing machine. The mowing machine includes mowing blades driven by a mowing motor. When detected that a load of the mowing motor is high, the controller controls to operate the mowing motor with high load according to the high-load-adaptive power map. The high-load-adaptive power map is defined such that a boundary rotation speed, when switching from an upper-limit torque constant region to an upper-limit torque decrease region, is lower than the upper-limit rotation speed of the upper-limit torque constant region in a power characteristic of the mowing motor determined by the mowing motor and the maximum voltage applied on the mowing motor.