Cordless BLDC Power Tool Current Control for High Torque
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Solution Overview
Problem
Brushless-type motors have not been widely used in power tools due to high cost and design challenges, particularly in hand-held cordless tools, which require balancing performance, size, weight, and cost considerations while harmonizing motor control electronics, power source requirements, and motor capabilities.
Innovation Solution
A cordless hand-held power tool incorporating a brushless direct current (BLDC) motor, a removable battery pack, and advanced electronics to achieve high-power and high-torque operation with balanced current delivery for both short-duration and long-duration tasks, using a switching array and motor controller to optimize power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If brushless-type motors are used in power tools, then performance and efficiency are improved, but cost and design complexity increase
Solution Approach 1:
The patent replaces the mechanical brush-commutator system with an electronic control system using MOSFETs and microcontrollers to achieve brushless motor operation. This substitution eliminates mechanical wear components while enabling precise electronic control of motor phases, resolving the contradiction between improved performance and increased complexity through modern electronic replacement of mechanical systems.
Solution Approach 2:
The motor control electronics are designed to universally control different motor configurations and power tool applications through a single integrated controller architecture. The system can adapt to various battery voltages (18V, 36V, 54V) and motor types, reducing design complexity by creating a multi-functional control platform that serves multiple purposes across different power tool applications.
2Weight of moving object
If hand-held power tool size is reduced, then portability is improved, but power delivery capability deteriorates
Solution Approach 1:
The patent employs parameter changes in the motor design including optimized winding configurations, advanced magnetic materials, and precision-tolerant rotor-stator geometries to achieve higher power density. These parameter optimizations allow the motor to deliver high power output from a reduced size, resolving the contradiction between weight reduction and power delivery capability.
Solution Approach 2:
The motor utilizes composite materials including high-energy-density permanent magnets, advanced magnetic alloys, and lightweight structural materials to achieve superior power-to-weight ratio. These composite materials enable the motor to maintain high power output while reducing overall mass, directly addressing the contradiction between portability and power delivery.
3Duration of action of moving object
If battery capacity is increased to improve runtime, then power availability is improved, but weight and size increase
Solution Approach 1:
The power management system incorporates feedback mechanisms including battery state-of-charge monitoring, current sensing, and thermal management to optimize power delivery in real-time. This feedback control allows the system to maximize runtime from available battery capacity without requiring excessive battery size, resolving the contradiction between runtime extension and weight/size increase through intelligent power management.
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
The BLDC motor system enables high instantaneous and continuous power output in a compact, lightweight design, overcoming thermal and operational limitations of traditional hand-held power tools, ensuring reliable performance across various applications.
Implementation Method 1
a brushless direct current (BLDC) motor
Data Source
AI summary
A cordless, hand-held power tool, such as a hammer drill/driver, a drill/driver, an impact driver, an impact wrench, etc., that includes a brushless direct current (“BLDC”) motor. Each of the hand-held power tool includes a removable and rechargeable battery pack, electronics, and a BLDC motor that have been designed and balanced to produce a high-performance-capable (e.g., high-power, high-current, high-torque) hand-held power tool. The hand-held power tool is capable of delivering high instantaneous (i.e., short duration) current to the BLDC motor for short-duration high power operation and high continuous (i.e., long duration) current to the BLDC motor for long duration high power operation. Additionally, the short and long duration power is capable of being provided in a smaller (in size) and lighter (in weight).