Brushless Power Tool Motor Control for Rapid Speed Switching
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Solution Overview
Problem
Existing power tools require a gradual adjustment process to change gear settings, leading to delayed responses and inability to achieve target rotational speeds, especially when switching between maximum and normal modes, which affects user satisfaction and tool efficiency.
Innovation Solution
A power tool with a multi-phase winding motor, a driver circuit, and a controller that adjusts the strength of the magnetic field through a controller-controlled conduction manner of power elements in the driver circuit, allowing rapid transitions between operating states to achieve desired rotational speeds and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gradual adjustment of operating gear is used, then the motor can maintain stable operation, but the response time is delayed and cannot meet urgent speed change requirements
Solution Approach 1:
The patent applies dynamics by making the magnetic field strength adjustable and variable during operation. The controller dynamically changes the conduction manner of power elements to adjust magnetic field strength according to different operating states, enabling the motor to adapt its performance characteristics in real-time rather than being fixed. This resolves the contradiction by allowing stable operation at normal gears while enabling rapid maximum speed when needed.
Solution Approach 2:
The patent changes the magnetic field strength parameter of the motor by controlling different conduction manners of power elements. By adjusting this physical parameter, the motor can operate in different modes (normal operation mode with higher magnetic field strength for stability, and maximum speed mode with lower magnetic field strength for rapid response). This parameter change enables the system to resolve the contradiction between response speed and operational stability.
2Productivity
If operating gear is adjusted gradually from maximum to normal, then the motor operates smoothly, but the adjustment process takes time and reduces productivity
Solution Approach 1:
The dynamic adjustment of magnetic field strength allows the motor to transition rapidly between operating states without requiring gradual gear changes. The controller can switch conduction manners of power elements to change magnetic field strength instantaneously, enabling the motor to go from maximum speed to normal operation immediately, thus eliminating adjustment time loss and improving tool usage efficiency.
Solution Approach 2:
The patent prepares multiple conduction manners of power elements in advance, each corresponding to different magnetic field strengths and operating states. When a speed change is needed, the controller simply switches between pre-configured conduction manners rather than adjusting gradually, enabling immediate response and eliminating adjustment time, thereby improving productivity.
3Speed
If the motor operates at maximum gear continuously, then high speed is achieved, but overheating occurs and reduces tool lifespan
Solution Approach 1:
The patent implements periodic action by automatically switching between different conduction manners of power elements based on operating state. When maximum speed is needed, the controller uses conduction manners that produce lower magnetic field strength, reducing motor temperature. This periodic switching between operating modes allows the motor to maintain high speed when needed while preventing continuous overheating, thus protecting tool lifespan.
Solution Approach 2:
The controller monitors the operating state of the motor and provides feedback to adjust the conduction manner of power elements accordingly. When the motor approaches maximum temperature during high-speed operation, the feedback mechanism triggers a switch to conduction manners that reduce magnetic field strength and consequently reduce temperature, preventing overheating and extending tool lifespan while maintaining high speed capability when needed.
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
Enables quick adjustment of rotational states, reduces overheating risks, and extends tool usage time by automatically switching between operating states based on detected parameters, enhancing user experience and tool efficiency.
Implementation Method 1
The operating element has a first operating state and a second operating state, where a strength of an effective magnetic field of the winding when the operating element is in the first operating state is less than a strength of an effective magnetic field of the winding when the operating element is in the second operating state. The controller is configured to control conduction manners of the plurality of power elements in the driver circuit according to an operating state of the operating element, so as to adjust the strength of the effective magnetic field of the winding and change the rotational state of the motor.
Data Source
AI summary
A power tool includes a motor, a switch, a driver circuit, an operating element, and a controller. The motor includes a multi-phase winding. The driver circuit has multiple power elements and is configured to change a rotational state of the motor. The operating element has a first operating state and a second operating state, where a strength of an effective magnetic field of the multi-phase winding when the operating element is in the first operating state is less than a strength of an effective magnetic field of the multi-phase winding when the operating element is in the second operating state. The controller is configured to control conduction manners of the multiple power elements in the driver circuit according to an operating state of the operating element, so as to adjust the strength of the effective magnetic field of the multi-phase winding and change the rotational state of the motor.