Motorized Cart Power Cutoff Circuit for Unintended Drive Prevention
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Solution Overview
Problem
Existing carts may inadvertently drive the motor due to malfunction of the motor control device when it should not be driven, leading to potential safety and operational issues.
Innovation Solution
Incorporating a switching element on the electric power supply path to the motor drive circuit, controlled by a separate switch circuit, which can switch between conduction and non-conduction states to prevent motor operation during malfunctions, ensuring the motor is only driven when intended.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor control device is used to control the motor, then the motor can be controlled to operate in manual mode and automatic mode, but the motor may inadvertently be driven due to malfunction of the motor control device when it should not be driven
Solution Approach 1:
A switching element is introduced as an intermediary component between the power supply and the motor drive circuit. This switching element acts as a mediator that physically disconnects the power supply path when activated, preventing any unintended motor operation regardless of the motor control device's state. The switching element is controlled by a separate switch circuit that monitors system conditions independently of the motor control device.
Solution Approach 2:
The control system is segmented into two independent parts: the motor control device for normal operation control, and a separate switch circuit with switching element for safety control. This segmentation allows the safety function to operate independently from the motor control function, so that a malfunction in the motor control device does not compromise the safety mechanism.
2Reliability
If a switching element and switch circuit are added to prevent unintended motor operation, then motor operation safety is improved, but device complexity increases
Solution Approach 1:
The safety control function is extracted as a separate, dedicated circuit (switch circuit with switching element) that is physically and functionally separated from the main motor control device. This extraction allows the safety mechanism to be implemented with minimal additional complexity - essentially just a switch and its control circuit - rather than trying to integrate safety features into the existing complex motor control device.
Data Source
AI summary
A cart may include: a driving wheel; a motor configured to rotate the driving wheel; a motor drive circuit configured to control electric power supply to the motor; a motor control device configured to control the motor via the motor drive circuit; a switching element arranged on an electric power supply path to the motor drive circuit; a switch circuit arranged separately from the motor control device and configured to switch the switching element between a conduction state and a non-conduction state; and an operation member arranged on the cart and configured to be operated by a user. The cart may operate in a manual mode in which the motor is driven when the operation member is on and the motor is stopped when the operation member is off, and in an automatic mode in which the motor is driven regardless of whether the operation member is on or off.