Dual-Battery Power Tool Control Circuit for Residual Voltage Isolation
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Solution Overview
Problem
Existing power tools with dual or multiple battery packs face issues with residual voltage on the socket after unplugging, leading to a risk of electrification due to the use of relays that occupy large space and are costly.
Innovation Solution
A power supply control circuit with a main control chip module, voltage detection circuit, and a switching mechanism using a field effect transistor and discharge resistor to automatically switch between battery packs, ensuring no residual voltage on the socket by discharging the energy storage capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relay is added at the output end of the power supply control circuit for isolation, then the connection between the external socket and the internal energy storage capacitor can be effectively cut off, but the relay occupies large space and increases cost
Solution Approach 1:
The patent extracts the isolation function from the traditional relay component and implements it using a combination of switching elements (MOSFETs or transistors) and control circuits integrated on the PCB. This removes the need for a separate relay component, significantly reducing PCB area while maintaining effective isolation between the external socket and internal energy storage capacitor.
Solution Approach 2:
The patent replaces the mechanical relay system with an electronic switching system using MOSFETs or transistors controlled by control circuits. This substitution eliminates the mechanical moving parts and large physical structure of relays, achieving the same isolation function with much smaller footprint and lower cost.
2Reliability
If a relay is added at the output end of the power supply control circuit for isolation, then the connection between the external socket and the internal energy storage capacitor can be effectively cut off, but the relay increases cost
Solution Approach 1:
The patent extracts the isolation function from the expensive relay component and implements it using standard electronic switching elements and control circuits that are more cost-effective. This reduces component costs while maintaining the essential safety function of isolating the external socket from the internal energy storage capacitor.
Solution Approach 2:
The patent replaces the costly mechanical relay with an electronic switching system using MOSFETs or transistors, which are generally less expensive and have no mechanical wear. This substitution reduces both component cost and long-term maintenance costs while achieving the same isolation reliability.
3Productivity
If the power supply control circuit automatically switches between different battery packs, then the productivity is improved, but the device complexity increases
Solution Approach 1:
The patent implements a universal control circuit that can manage multiple battery packs using the same switching mechanism and control logic. The control circuit is designed to handle any number of battery packs by selecting appropriate switches, reducing the need for separate control circuits for each battery and thereby limiting the increase in complexity while maintaining high switching efficiency.
Solution Approach 2:
The patent employs dynamic switching control where the control circuit actively monitors battery status and automatically selects the appropriate battery pack based on real-time conditions. This dynamic operation enables efficient automatic switching between multiple battery packs without requiring complex manual intervention, achieving high productivity with manageable circuit complexity.
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 solution reduces PCB area and cost by minimizing residual voltage on the socket, eliminating the risk of electrification, and enabling efficient battery pack switching.
Implementation Method 1
a switching mechanism using a field effect transistor and discharge resistor to automatically switch between battery packs
Implementation Method 2
ensuring no residual voltage on the socket by discharging the energy storage capacitor
Data Source
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AI summary
The present application provides power supply control circuits, power tools, and power tool systems. The power supply control circuit includes: a main control chip module connected to battery packs; control circuits connected in parallel and connected to the main control chip module and provided on a power supply path from the battery pack to a power tool to control connection and disconnection of the battery packs; and a voltage detection circuit connected to the power supply path and the main control chip module. The main control chip module controls the connection and disconnection of the battery packs through the control circuit based on feedback from the voltage detection circuit, and when the voltage detection circuit detects that the voltage of a currently connected battery pack is less than a predetermined value, controls the currently connected battery pack to be disconnected and select the other battery pack to be connected.