Battery Pack Charging Circuit With Fused FET High-Current Path
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Solution Overview
Problem
Cordless electrical devices have limited run-time due to battery pack capacity, and existing charging circuitry cannot handle higher charging currents without adverse effects such as excessive heating or damage, limiting fast charging capabilities.
Innovation Solution
A battery pack with a charging circuit that includes a N-Channel FET and a fuse rated for higher currents, coupled with an electronic controller to manage the charging process, allowing for charging currents between 6 A and 20 A, enabling faster charging without component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher charging current is provided to decrease charging time, then charging speed is improved, but components (PCB, fuse, FET) experience excessive heating and may be damaged
Solution Approach 1:
The charging system dynamically adjusts the charging current based on real-time monitoring of temperature and component status. The controller modifies the charging parameters during the charging process to optimize charging speed while preventing excessive heating and component damage, transitioning from static to dynamic current control.
Solution Approach 2:
The system implements feedback control by monitoring charging current, temperature, and component status, then adjusting the charging current accordingly. The controller receives feedback from sensors and modifies the charging parameters to maintain optimal charging speed while preventing harmful effects such as excessive heating and component damage.
2Duration of action of moving object
If battery pack capacity is increased to extend run-time, then duration of action is improved, but charging time increases proportionally
Solution Approach 1:
The system changes the charging current parameter dynamically during the charging process. By adjusting the charging current based on battery state, temperature, and component capacity, the system achieves faster charging times for high-capacity battery packs without causing component damage or excessive heating, thereby reducing the loss of time while maintaining extended run-time.
3Reliability
If charging current is limited to protect components, then reliability is improved, but charging speed deteriorates
Solution Approach 1:
The system transitions from static current limiting to dynamic current control. The charging current is adjusted in real-time based on component status and temperature monitoring, allowing the system to maintain high charging speeds when components are within safe operating parameters while automatically reducing current when protection is needed, thus achieving both reliability and charging speed.
Solution Approach 2:
The system uses feedback control to monitor component status and adjust charging current accordingly. When components are operating within safe parameters, the system allows higher charging currents for faster charging. When components approach unsafe thresholds, the system reduces current to protect reliability. This feedback mechanism resolves the contradiction by making component protection conditional rather than constant.
Data Source
AI summary
One embodiment provides a battery pack including a housing, a plurality of battery cells supported by the housing, and a terminal block. The terminal block is configured to be coupled to a power tool to provide operating power from the plurality of battery cells to the power tool. The terminal block has a positive power terminal, a charging terminal, and a ground terminal. The battery pack also includes a charging circuit provided between the charging terminal and the plurality of battery cells. The charging circuit is configured to receive and transfer charging current above 12 Amperes to the plurality of battery cells during charging. The charging circuit includes a charging switch and a fuse coupled between the charging terminal and the charging switch.