Power Tool Motor Phase Control Across Battery Pack Capacities
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Solution Overview
Problem
Existing power tools are inefficient when using battery packs with different capacities, as they either underutilize high-capacity packs or draw excessive current from low-capacity packs, leading to inefficiency and potential harm.
Innovation Solution
A system that includes a controller in each power tool to identify the battery pack type and adjust the conduction band and advance angle of the motor to optimize current draw based on the battery pack's impedance, allowing efficient use of packs with varying capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power tool designed for low capacity battery pack uses high capacity battery pack, then power capability is improved, but battery pack is underutilized and efficiency decreases
Solution Approach 1:
The controller dynamically adjusts motor operating parameters (conduction band and advance angle) based on the detected battery pack capacity. When a high-capacity battery pack is detected, the controller increases the conduction band and advance angle to allow the motor to draw more current, fully utilizing the battery's power capability. This dynamic adaptation resolves the contradiction by ensuring the battery pack operates at optimal efficiency while the motor receives appropriate power levels.
Solution Approach 2:
The system changes motor control parameters (conduction band angle and advance angle) based on battery pack capacity detection. The controller identifies battery pack type and adjusts these parameters to optimize the match between battery capability and motor demand, preventing underutilization of high-capacity packs while maintaining efficient operation.
2Adaptability or versatility
If a power tool designed for high capacity battery pack uses low capacity battery pack, then compatibility is improved, but excessive current draw harms the battery pack
Solution Approach 1:
The controller implements feedback by detecting the battery pack type through impedance measurement and continuously monitoring current draw. Based on this feedback, the controller adjusts the conduction band and advance angle to limit current to safe levels for the detected battery capacity. This prevents harmful excessive current draw from low-capacity packs while maintaining compatibility across different battery types.
Solution Approach 2:
The system dynamically adjusts motor control parameters based on real-time detection of battery pack capacity. When a low-capacity battery pack is detected, the controller reduces the conduction band and advance angle to limit current draw to safe levels, preventing battery damage while still allowing the tool to operate with the smaller battery pack.
3Reliability
If controller limits maximum current drawn from battery pack, then battery pack protection is improved, but motor performance may be reduced
Solution Approach 1:
The controller changes motor control parameters (conduction band and advance angle) based on battery pack capacity detection. For high-capacity battery packs, the controller increases these parameters to allow higher current draw and maintain full motor performance. For low-capacity packs, the controller reduces these parameters to limit current to protective levels. This resolves the contradiction by making motor performance adaptive to battery capability rather than uniformly limited.
Solution Approach 2:
The system dynamically adjusts the balance between battery protection and motor performance by varying control parameters based on detected battery capacity. The controller optimizes the conduction band and advance angle to allow maximum safe current draw for each battery type, ensuring both battery protection and appropriate motor performance without unnecessary limitations.
Data Source
AI summary
A system is provided with a set of removable battery packs and a set of power tools each including a motor, a controller, and a battery receiving portion. For each power tool, the controller is configured to identify a type of battery pack coupled to the battery receiving portion and set a conduction band associated with phases of the motor or an advance angle by which phases of the motor are shifted based on the identified type of the battery pack.