BLDC Power Tool Inverter for High Power Without Heavy Batteries
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Solution Overview
Problem
Power tools face limitations in versatility and efficiency due to the need for specific AC or DC power supplies, with cordless tools lacking in power and runtime for heavy-duty applications and being hindered by weight, while corded tools require constant AC power access.
Innovation Solution
A power tool system featuring a convertible battery pack that can operate across multiple voltage configurations, allowing it to be used with both AC and DC power supplies, including a charger that adapts to different battery pack voltages, enabling operation with various power tools and AC mains power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cordless power tools use higher voltage and capacity batteries to achieve heavy-duty applications, then power and runtime are improved, but weight increases creating ergonomic disadvantage
Solution Approach 1:
The power tool is designed with a universal motor and control system that can operate with multiple power supply types (battery packs of various voltages and AC power supply). This allows the tool to achieve heavy-duty power when connected to AC power without requiring heavy high-capacity batteries, while still maintaining cordless operation capability with lighter batteries for portability-critical applications.
2Duration of action of moving object
If cordless power tools use higher voltage and capacity batteries to achieve heavy-duty applications, then runtime is improved, but weight increases creating ergonomic disadvantage
Solution Approach 1:
The dual power supply capability allows the tool to achieve unlimited runtime when connected to AC power for stationary heavy-duty work, while accepting lighter battery packs for mobile applications where extended runtime is less critical than portability. The control system automatically adapts to the available power source.
3Power
If corded power tools are used for heavy-duty applications requiring higher power, then power and runtime are improved, but the tool requires connection to AC power supply which is not practical in many applications
Solution Approach 1:
The power tool incorporates a universal motor design with control circuitry that accepts both AC power input and DC battery pack input. The system includes voltage detection and switching mechanisms that automatically configure the motor operation based on the connected power source, enabling the tool to function as either corded or cordless depending on application requirements.
4Power
If power tools are designed to operate with specific AC or DC power supplies, then motor performance is optimized, but versatility across different power supply types is reduced
Solution Approach 1:
The motor is designed as a universal motor capable of operating on both AC and DC power sources. The control system includes detection circuitry that identifies the power source type and adjusts operating parameters accordingly, maintaining optimal motor performance whether powered by AC mains or DC battery packs of various voltages.
Solution Approach 2:
The control system dynamically adjusts motor operating parameters such as voltage, current, and switching frequency based on the detected power source. When AC power is detected, the system configures for higher power operation; when battery packs are detected, the system adjusts parameters based on the specific battery voltage and capacity to optimize performance within available power constraints.
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 system enhances the versatility and efficiency of power tools by allowing them to operate across different voltage configurations, improving runtime and power capabilities without the need for constant AC power access, and reducing weight constraints in cordless tools.
Implementation Method 1
a brushless direct current (BLDC) motor including a rotor and a stator
Data Source
AI summary
A power tool is provided including a power supply interface receiving a medium-voltage-rated removable battery pack having a maximum rated voltage in the range of 40 to 80 volts, and a brushless direct current (BLDC) motor. The motor includes a rotor and a stator having at least three stator windings corresponding to at least three phases of the motor, the rotor being moveable by the stator when the stator windings are appropriately energized within the corresponding phases. A multi-phase inverter bridge circuit is disposed between the power supply interface and the motor, and a controller is configured to output drive signals to the inverter bridge circuit to control flow of current from the battery pack to the motor such that the motor produces a maximum power output of at least approximately 1750 watts at a torque of approximately 1.5 to 2 Newton-meters.