Electric Chainsaw Motor Control for Torque and Power Balance
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Solution Overview
Problem
Users of electric hand-held tools, such as chain saws, face challenges in safely and efficiently approaching and maintaining a suitable working area due to the high power consumption and torque output at low speeds, making it difficult to control the feed force and achieve efficient cutting performance.
Innovation Solution
The electric drive motor is designed with a control characteristic that reduces input power and increases torque as speed decreases, creating a working range where the user can easily operate the tool with optimal efficiency and adequate cooling, ensuring a wide, easily approachable area with high electrical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor operates with high current consumption at low speeds to provide high torque output, then the cutting performance increases, but the power consumption increases and makes it difficult to control and maintain a suitable working area
Solution Approach 1:
The patent applies dynamics by making the motor control characteristic adjustable and adaptive. The control characteristic can be dynamically changed between different modes (first and second characteristics) depending on operating conditions, allowing the system to optimize the relationship between torque and power consumption in real-time based on the working requirements and battery state.
Solution Approach 2:
The patent changes the control parameters of the electric motor by implementing different control characteristics. The first control characteristic limits current consumption more strictly, while the second characteristic allows higher current consumption. By switching between these parameter sets, the system optimizes the balance between torque output and power consumption for different operating scenarios.
2Productivity
If the user applies increasing feed force to achieve higher cutting performance, then the torque output increases, but it becomes difficult to safely approach and maintain a suitable working area with good efficiency
Solution Approach 1:
The patent implements feedback by continuously monitoring the operating state of the electric motor and automatically adjusting the control characteristic accordingly. The control unit receives information about the current operating conditions and switches between different control characteristics to maintain optimal cutting performance while preventing excessive feed force application, thus making the tool easier to control.
Solution Approach 2:
The system performs self-service by automatically regulating its own operation through the control unit that monitors and adjusts the motor characteristics without requiring manual intervention from the user. The control system independently manages the balance between cutting performance and ease of operation by switching between different control modes based on real-time conditions.
3Power
If the electric motor operates at high power consumption to deliver high torque, then the cutting capacity increases, but the thermal load on the motor increases risking thermal damage
Solution Approach 1:
The patent applies preliminary anti-action by preemptively limiting the current consumption and power output of the electric motor through the control characteristics. By designing the control system to prevent excessive power consumption before it occurs, the system avoids generating excessive thermal load that would lead to thermal damage, thus protecting the motor in advance.
Solution Approach 2:
The patent applies partial action by not always operating the motor at maximum power capacity. Instead, the control characteristics are designed to limit power consumption to appropriate levels based on operating conditions, using only the necessary amount of power required for the task, thereby reducing unnecessary thermal generation while maintaining sufficient cutting performance.
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
This design allows for optimal cutting performance and thermal balance, preventing thermal damage while maintaining high electrical efficiency, with the electric motor operating above 78% of its maximum efficiency and torque increasing by up to 15% as speed falls, ensuring a stable and efficient cutting experience.
Implementation Method 1
an electric drive motor (2), in particular an electric motor chain saw, with a motor-specific characteristic curve (3) of the motor current (I) consumed above the speed (n)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a handheld electric chainsaw whose electric drive motor (2) has a motor-specific characteristic curve (3) of the current drawn as a function of the rotational speed (n) of the motor (2). A control unit (4) controls the current (I) flowing through the electric drive motor (2) below an engagement speed (nE) to values that lie below the motor-specific characteristic curve (3).To establish a user-perceived operating point within a working range (A) of the chainsaw in a predetermined speed range (Δn), a control characteristic (10) of the electrical input power (P) of the electric drive motor (2) is defined above the engagement speed (nE). This control characteristic reduces the input power (P) in the predetermined speed range (Δn) to an approximately constant average power (PR) such that the torque (M) of the drive motor (2) increases as the speed (n) decreases within the predetermined speed range (Δn). The predetermined speed range (Δn) lies above a motor speed (n) of approximately 50% of the maximum no-load speed (nmax) of the motor-specific characteristic curve (3) of the drive motor (2).