BLDC Power Tool Inverter Control for High Torque Without Heavier Batteries
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Solution Overview
Problem
Existing power tools are limited by their power and runtime capabilities, with corded tools requiring an AC power source and cordless tools being inadequate for heavy-duty applications due to weight and voltage constraints, leading to ergonomic disadvantages and limited acceptance in the industry.
Innovation Solution
A power tool system featuring a convertible battery pack that can operate in multiple configurations to match the voltage requirements of different power tools, allowing for operation with both AC and DC power sources, and a motor control circuit that seamlessly switches between AC and DC power without conversion, enabling consistent performance across various voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher voltage and capacity batteries are used to increase power and runtime for heavy-duty applications, then power and runtime are improved, but battery weight increases creating ergonomic disadvantages
Solution Approach 1:
The power tool is designed with a universal power system that can accept both AC power input and DC battery power input through a common motor and control circuitry. This multi-functionality allows the same tool to operate in corded mode for maximum power output or cordless mode with reduced weight, eliminating the need to choose between power and portability
Solution Approach 2:
The power tool incorporates a dynamic power source selection capability where the user can switch between AC and DC power sources based on the application requirements. The control system dynamically adjusts operating parameters based on the detected power source type, optimizing performance for each mode while managing the weight-power tradeoff
2Duration of action of moving object
If higher voltage and capacity batteries are used to increase runtime for heavy-duty applications, then runtime is improved, but battery weight increases creating ergonomic disadvantages
Solution Approach 1:
The dual-power capability allows the tool to achieve extended runtime through AC power connection when working in fixed locations, eliminating the runtime-weight compromise. The same tool provides both unlimited AC-powered runtime and portable battery-powered operation, giving users flexibility to optimize for either duration or mobility based on the work environment
3Power
If separate AC and DC power tools are manufactured for different applications, then performance for specific applications is optimized, but device complexity and variety increases
Solution Approach 1:
The invention merges the previously separate AC-powered and DC-powered tool designs into a single unified platform. The tool integrates both AC and DC power input interfaces, a universal motor design that handles both power types, and integrated control systems that manage both power sources, thereby consolidating what were previously two separate tool categories into one versatile device
Solution Approach 2:
By designing the tool with universal power acceptance capability, the invention eliminates the need for users to maintain separate tool inventories for AC and DC applications. The same motor housing, tool mechanism, and control system can operate with either power source, providing true versatility across all power tool applications
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 provides a versatile power tool that can handle heavy-duty tasks with consistent performance, eliminating the need for separate AC and DC power tools and reducing ergonomic burdens by optimizing battery weight and power delivery.
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 removable battery pack, a brushless direct current (BLDC) motor including a rotor and a stator, and a multi-phase inverter bridge circuit. A controller is provided to output drive signals to the inverter bridge circuit to control flow of current from to the motor, where each drive signal is activated within each corresponding phase of the motor within a conduction band. The controller is configured to control a length of the conduction band at a variable value within a first torque range below a torque threshold and at a substantially constant value within a second torque range above the torque threshold. The torque threshold is greater than approximately 1 Newton-meters and the motor produces a maximum power output of at least approximately 1250 watts at the torque of approximately 1 Newton-meters.