Power Tool Battery Identification via Voltage Change Detection
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Solution Overview
Problem
Conventional power tools cannot identify the type of battery pack connected, leading to potential degradation or damage of battery cells during high-load operations, especially in 1-parallel configurations, and existing solutions that add a special terminal for identification increase costs and reduce efficiency.
Innovation Solution
A power tool with a motor, connecting unit, voltage detection unit, and controller that detects voltage changes to determine the type of secondary battery and restrict motor operation based on the battery type, internal resistance, and cumulative charge, without the need for a special terminal, thereby preventing prolonged high-load usage that could damage battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a special terminal is added to the power tool for referencing the identification resistor in the battery pack, then the power tool can identify the type of battery, but the cost increases due to the extra terminal
Solution Approach 1:
The existing connection terminals are made multi-functional by using them not only for power connection but also for battery type identification through impedance measurement. The same terminals that connect the battery to the power tool are utilized to detect the identification resistor, eliminating the need for dedicated identification terminals.
Solution Approach 2:
The battery pack's identification resistor is referenced through the existing connection terminals that are already part of the power connection system. The system uses its own existing infrastructure (connection terminals) to perform the identification function, rather than requiring separate dedicated components.
2Reliability
If 1-parallel battery packs are mechanically prevented from connecting to power tools, then battery cell degradation is avoided, but operating efficiency is reduced since these batteries cannot be used even for short-period or low-load operations
Solution Approach 1:
The power tool dynamically adjusts its operation mode based on the detected battery type. For 1-parallel battery packs, the system automatically switches to intermittent operation with forced cooling periods, while allowing 2-parallel and higher configurations to operate continuously. This dynamic adaptation protects vulnerable battery types while maximizing the utility of all battery configurations.
Solution Approach 2:
The operating parameters (duty cycle, continuous operation time) are changed based on the detected battery configuration. The controller modifies operational characteristics such as interrupting motor operation after a predetermined time for 1-parallel batteries, thereby protecting them from overheating while still permitting useful work during allowed periods.
3Productivity
If the power tool allows continuous high-load operation with 1-parallel battery packs, then productivity is maintained, but battery cells become degraded or damaged due to generated heat
Solution Approach 1:
The power tool implements periodic interruption of motor operation when using 1-parallel battery packs. The motor operates for a predetermined time and then is forcibly stopped for cooling, creating a periodic on-off cycle. This prevents continuous heat accumulation in the battery cells while still allowing productive work to be performed during the active periods.
Solution Approach 2:
The controller proactively interrupts motor operation before critical heat damage can occur to the battery cells. By detecting the battery configuration and preemptively implementing duty cycle limitations, the system prevents the harmful thermal effects from developing to damaging levels.
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 power tool effectively determines the type of secondary battery and restricts its operation to prevent battery degradation, enhancing battery life and reducing the risk of damage without adding a dedicated terminal, thus maintaining efficiency and reducing costs.
Implementation Method 1
a voltage detection unit configured to detect a voltage of the secondary battery connected to the connecting unit
Data Source
AI summary
A power tool includes a motor, a connecting unit, and a controller. The connecting unit is configured to be connected to a secondary battery. A voltage detection unit is configured to detect a voltage of the secondary battery connected to the connecting unit. The controller is configured to acquire change of the detected voltage. The controller restricts the operation of the motor when the change of the voltage is a first value.