Power Tool Relay Control Circuit for Battery Safety
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Solution Overview
Problem
Garden power tools with multiple battery packs connected in series or parallel face risks of electrical shock and mutual charging due to exposed terminals and voltage differences, compromising safety and endurance.
Innovation Solution
A power tool with a relay control circuit that switches between battery packs, using a controller and relay switch circuits to ensure only one pack is active at a time, preventing electrical shock and mutual charging by detecting energy and user states of battery packs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple battery packs are connected in parallel to achieve high power and long-time endurance, then the power and endurance of the power tool are improved, but the risk of electrical shock and mutual charging between battery packs increases due to exposed terminals and voltage differences
Solution Approach 1:
The patent divides the battery pack system into independent units, each with its own relay switch circuit. The controller segments the control of multiple battery packs by generating individual battery pack selection signals for each relay switch circuit, allowing independent control and isolation of each battery pack to prevent electrical shock and mutual charging while maintaining high power capability through selective parallel connection.
Solution Approach 2:
The relay switch circuit acts as an intermediary between the controller and the battery packs. It mediates the electrical connection by using relay switches that can be opened or closed based on controller signals, thereby controlling the connection state of each battery pack. This intermediary mechanism prevents direct exposure of terminals and eliminates the risk of electrical shock and mutual charging.
2Duration of action of moving object
If multiple battery packs are connected in parallel to achieve long-time endurance, then the operational duration is improved, but the complexity of the control system increases due to the need for relay control circuits and switching mechanisms
Solution Approach 1:
The patent merges the control functions into a centralized controller that manages multiple relay switch circuits. The controller integrates the detection of battery pack states and the generation of selection signals, while the relay switch circuits are standardized and can be replicated for each battery pack. This merging approach simplifies the overall control architecture and makes the system more manageable despite handling multiple battery packs.
Solution Approach 2:
The relay switch circuits are pre-configured with relay switches that can be rapidly opened or closed based on controller signals. The controller detects battery pack states in advance and generates selection signals before switching is needed, allowing the system to quickly transition between battery packs without complex real-time decision-making during operation, thereby maintaining simplicity while achieving long endurance through seamless switching.
3Reliability
If relay switch circuits are used to control switching between battery packs, then the safety is improved by preventing electrical shock and mutual charging, but the device complexity increases due to additional relay switches and control circuits
Solution Approach 1:
The patent applies local quality by implementing relay switch circuits with specific protective functions at each battery pack connection point. Each relay switch circuit is designed with localized control capabilities, where the relay switch is positioned to isolate individual battery packs from the output terminals. This localized approach ensures safety at each connection point without requiring a completely complex system-wide redesign, as each relay switch circuit operates independently to prevent electrical shock and mutual charging.
Data Source
AI summary
The invention provides a power tool, which comprises a motor, at least two battery packs supplying power to the motor and arranged in parallel. The power tool also comprises a relay control circuit used for connecting the motor and the battery packs, and the relay control circuit is provided with a controller, and a plurality of relay switch circuits connected with the controller. The controller is used for detecting the electric energy and/or an user state of battery packs and generates battery pack selection signals, the relay switch circuits and the battery packs are arranged one-to-one, the relay switch circuits receive the battery pack selection signals and control turning on/turning off of relays switches therein, and further switch the battery packs in the on state, to make only one battery pack in the on state at the same time.