Electric Tool Motor Stop Circuit for Hardware-Based Reliability
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Solution Overview
Problem
As electric power tools become more sophisticated and complex, existing technologies face challenges in maintaining high reliability due to the increased complexity of internal structures, leading to potential failures and reduced performance.
Innovation Solution
The electric working machine incorporates a motor, information output circuit, control circuit, and drive stop circuit, where the motor stop operation is executed through hardware processing rather than software, ensuring that the motor is stopped even if permitted to be driven, and physical quantities such as voltage and temperature are monitored to prevent motor operation when outside permitted ranges, enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If motor control is implemented through software processing, then flexibility and ease of control are improved, but reliability deteriorates due to potential software failures and delays
Solution Approach 1:
The control system is divided into two independent parts: a software-based control circuit for normal operation and a hardware-based drive stop circuit for safety-critical stop functions. This segmentation allows the software to maintain flexibility while the hardware ensures reliable motor stopping even when software fails.
Solution Approach 2:
The drive stop circuit acts as an intermediary safety mechanism between the software control and the motor driver. It monitors the motor stop permission signal independently and can force the motor to stop by controlling the motor driver directly, serving as a mediator that ensures safety without interfering with normal software control operations.
2Reliability
If hardware processing is used for motor stop operation, then reliability is improved, but device complexity increases
Solution Approach 1:
The drive stop circuit is merged with the existing control circuit to share common components such as the microcontroller unit, signal processing circuits, and power supply. This integration reduces the overall complexity increase while maintaining the independent hardware-based stop functionality.
Solution Approach 2:
The control circuit is designed to serve multiple functions: normal motor control through software and emergency stop control through hardware. The drive stop circuit utilizes existing signal lines and components for its monitoring functions, making the added hardware serve multiple purposes rather than requiring dedicated separate systems.
3Reliability
If dual monitoring system is implemented, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The same detection circuit is used by both the control circuit and drive stop circuit to monitor physical quantities such as temperature and voltage. This shared hardware approach eliminates the need for duplicate sensors and signal conditioning circuits, reducing manufacturing costs while maintaining dual-monitoring reliability.
Solution Approach 2:
The detection circuit is designed with multi-functionality to serve both software-based control decisions and hardware-based stop decisions. The circuit outputs signals that can be processed independently by both control systems, allowing one physical component to fulfill multiple monitoring roles without requiring additional hardware.
Data Source
AI summary
An electric working machine in one aspect of the present disclosure includes a motor, an information output circuit, a control circuit, and a drive stop circuit. The information output circuit outputs state information that indicates a state of the electric working machine. The control circuit executes a motor control process in accordance with a computer program. The drive stop circuit executes a motor stop operation. The motor stop operation includes disabling a permission to drive the motor by the control circuit to stop the motor in response to the state information indicating that the motor should be stopped. The motor stop operation is implemented by hardware.