Electric Motor Control for Power-Assisted Grass Cutter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric work machines with electric motors struggle to maintain extended operation periods due to high electric power consumption, making it difficult to integrate large batteries in compact designs, such as walk-behind grass cutters.
Innovation Solution
Implementing a control mechanism that eliminates abrupt current increases during clutch engagement by stopping electric motor energization for a short period before engaging the clutch, allowing for reduced power consumption and extended operation without large batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a large battery is mounted to extend operation period, then operation duration increases, but machine size and weight increase making it unsuitable for walk-behind design
Solution Approach 1:
The electric motor is controlled to operate intermittently rather than continuously. The motor starts rotation before clutch engagement, maintains rotation during engagement, and stops after engagement. This periodic operation pattern reduces average power consumption and eliminates the need for large battery capacity to sustain continuous operation.
Solution Approach 2:
The control strategy changes the operational parameters of the electric motor by adjusting its rotation state (starting, maintaining, stopping) relative to clutch engagement timing. This parameter optimization reduces peak current demands and average power consumption, enabling extended operation with smaller battery capacity.
2Speed
If clutch is engaged immediately to transmit power to cutting blade, then operational responsiveness improves, but abrupt current increase occurs causing high power consumption
Solution Approach 1:
The electric motor is started to rotate before the clutch is engaged. This preliminary action ensures the motor is already running when the clutch engages, preventing abrupt current increases and reducing peak power consumption while maintaining operational responsiveness.
Solution Approach 2:
The control system cushions the power transmission shock by having the motor already rotating before clutch engagement. This beforehand preparation absorbs the mechanical shock and electrical current surge that would otherwise occur during sudden engagement, reducing overall power consumption.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention includes: a cutting blade; an electric motor (5) that rotationally drives the cutting blade; a clutch that engages and disengages transmission of motive power between the electric motor (5) and the cutting blade; operation means for operating the clutch; and controller (30) for controlling operation of the electric motor (5). By means of the operation means, it is possible to switch between a state in which the clutch is disengaged in which motive power of the electric motor (5) is not transmitted to the cutting blade and a state in which the clutch is engaged and motive power of the electric motor (5) is transmitted to the cutting blade. By stopping energization of the electric motor (5) after a state in which the clutch is disengaged is released, and restarting the electric motor (5) after a prescribed time period elapses from the time of stopping rotation of the electric motor (5), the controller (30) stops rotation of the electric motor (5) during a period that includes a moment at which the clutch is engaged.