Power Tool Dual-Controller Circuit for Safe Power-Off
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Solution Overview
Problem
Existing power tools face challenges in achieving high safety and operability in power on-off control due to the use of large-volume high-current switches, which are difficult to operate and prone to contact damage from continuous high currents.
Innovation Solution
A power tool design incorporating a dual-controller system with a signal detection circuit, power-on control switch, and driver circuit using semiconductor switch elements, where the first controller controls the power-on control switch and the second controller manages the motor's energized state, ensuring safe and efficient power on-off operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-current mechanical switch is used to control power on/off, then control safety is improved, but operability deteriorates due to large volume and difficulty of operation
Solution Approach 1:
The patent replaces the traditional mechanical high-current switch with an electronic control system consisting of controllers, driver circuits, and semiconductor switch elements. This substitution eliminates the need for manual operation of large mechanical switches while maintaining safety through electronic control mechanisms, directly resolving the contradiction between safety and ease of operation.
Solution Approach 2:
The patent introduces intermediate control components (controllers and driver circuits) that mediate between the user interface and the motor power supply. These intermediaries enable safe power control without requiring direct manual operation of high-current switches, improving operability while maintaining control safety through layered control architecture.
2Reliability
If a high-current mechanical switch is used for power control, then power-off control capability is improved, but the switch contacts are damaged by continuous high current
Solution Approach 1:
The patent replaces the mechanical high-current switch with solid-state semiconductor switch elements controlled by driver circuits. This eliminates physical contacts that are susceptible to damage from continuous high current, while maintaining the power-off control capability through electronic switching mechanisms that have no wear-prone contact points.
Solution Approach 2:
The patent changes the operating parameters of the switching system by transitioning from mechanical contacts to semiconductor devices. Semiconductor switch elements can handle high currents without contact damage because they use solid-state conduction rather than physical contact, fundamentally changing how high current is managed while preserving power control functionality.
3Device complexity
If a single-chip microcomputer is used for control, then device complexity is reduced, but safety deteriorates in case of microcomputer failure
Solution Approach 1:
The patent segments the control system into multiple independent controllers (first controller and second controller) with distinct functions. The first controller manages power supply control and the second controller manages motor control, creating functional redundancy. This segmentation ensures that if one controller fails, the other can still maintain basic safety functions, resolving the contradiction between simplicity and safety.
Solution Approach 2:
The patent implements beforehand cushioning by designing a control system where the first controller can independently cut off power supply in case of failure of the second controller or other critical failures. This pre-planned safety mechanism ensures that even if the main control fails, the system can still achieve safe power-off, cushioning against the risks of single-chip failure while maintaining reasonable complexity.
Data Source
AI summary
A power tool includes a motor, a signal switch, a signal detection circuit, a power-on control switch, a first controller, and a second controller. The signal switch is used to switch a power on/off state of the power tool. The signal detection circuit is configured to output a detection signal according to a connection state of the signal switch. The power-on control switch is connected to the second controller. The first controller is configured to control an on/off state of the power-on control switch. When the signal detection circuit outputs a power-off signal, the first controller controls the power-on control switch to be turned off so that the second controller is de-energized and the motor stops rotating. When the power-on control switch still remains on, the second controller controls the switch elements in the driver circuit to be turned off so that the motor stops rotating.