Electric Tool Battery Pack Identification and Motor Control
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Solution Overview
Problem
Conventional electric tools with removable battery packs face limitations in using higher voltage packs, leading to safety concerns and motor breakdowns due to temperature rises, especially when users need to switch to higher voltage packs for short periods.
Innovation Solution
An electric tool with a control circuit that identifies the connected battery pack type and adjusts motor output through PWM control, limiting high-voltage packs' usage to prevent excessive temperature and ensure safety, by switching between different motor drive methods like 120° conduction and overlapping conduction, and controlling advance angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric tool is configured to use only proper battery packs with matching voltage, then motor safety and reliability are ensured, but user convenience is reduced when higher voltage packs are needed for short periods
Solution Approach 1:
The control circuit dynamically adjusts motor output based on real-time temperature feedback. When a higher voltage battery pack is connected, the system initially operates at full power but automatically reduces output when temperature thresholds are exceeded, allowing flexible battery selection while preventing motor damage through adaptive control
Solution Approach 2:
A temperature detection device continuously monitors motor temperature and provides feedback to the control circuit. The control circuit uses this feedback to automatically adjust or limit motor output when temperature exceeds predetermined thresholds, enabling safe use of higher voltage battery packs without compromising motor reliability
2Adaptability or versatility
If the electric tool allows use of higher voltage battery packs without restrictions, then user convenience and versatility improve, but motor temperature rises causing breakdowns and user discomfort
Solution Approach 1:
The system preemptively limits motor output based on predicted temperature rise when higher voltage battery packs are detected. By anticipating the thermal problem before it occurs, the control circuit proactively adjusts power delivery to prevent excessive temperature rise while still allowing the use of versatile battery packs
Solution Approach 2:
The control system dynamically modifies motor operating parameters in real-time based on battery pack voltage and temperature conditions. When higher voltage packs are used, the system automatically adjusts current, duty cycle, and power delivery to maintain optimal temperature levels, enabling broad battery compatibility without thermal damage
3Temperature
If the control circuit limits motor output when high-voltage battery packs are connected, then motor temperature control improves, but power and productivity are reduced
Solution Approach 1:
The control circuit implements periodic temperature monitoring and pulsed power delivery adjustments. Rather than continuously limiting power, the system periodically checks temperature and applies brief power reduction cycles when thresholds are approached, maintaining average power levels while preventing thermal accumulation through intermittent control actions
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
This solution enhances convenience by allowing the use of multiple battery pack types while maintaining safety and endurance, preventing motor overheating and reducing the risk of user injury, even when higher voltage packs are used temporarily.
Implementation Method 1
An electric tool with a control circuit that identifies the connected battery pack type and adjusts motor output through PWM control
Implementation Method 2
switching between different motor drive methods like 120° conduction and overlapping conduction
Implementation Method 3
switching between different motor drive methods like 120° conduction and overlapping conduction
Implementation Method 4
controlling advance angles
Data Source
AI summary
An electric tool comprises a removable battery pack 2 as a power supply, a motor M as a power source, a drive unit being driven by said motor, a switch SW as an operation input unit, and a control circuit CPU controlling the driving of said motor according to the operation of said switch. The electric tool further comprises a power supply connection unit that enables a plurality of battery pack types, which have different rated output voltages, to be selectively connected, and an identification means that identifies the type of said battery pack that has been connected. Said control circuit is configured to control an output of said motor based on identification information for the type of said battery pack that has been connected, provided by said identification means.