Motor Control Circuit With Limit-Switch Power Cutoff
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Solution Overview
Problem
Existing direct current motor control systems in medical devices face issues with electromagnetic interference and sparks due to inductive loads, unreliable position feedback, and software delays in cutting off power supply, compromising reliability and security.
Innovation Solution
A motor control circuit with a switch triode and limit switch system that directly receives feedback signals to control power supply cutoff, eliminating reliance on relays and software, thereby reducing electromagnetic interference and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relay or contact is used to cut off the motor's power supply when arriving at a limit switch, then the motor motion is stopped, but electric sparks occur due to the inductive load, weakening the circuit's reliability
Solution Approach 1:
The patent extracts the power cutoff function from the relay/contactor and relocates it to the limit switch itself. The limit switch directly opens the main power circuit without involving relays or contactors, eliminating the source of electric sparks while maintaining the motor stopping function.
Solution Approach 2:
The patent introduces an intermediary circuit configuration where the limit switch directly controls the power supply to the motor through a switch triode, bypassing the need for relays or contactors. This intermediary structure eliminates the harmful sparking effect while maintaining reliable power cutoff.
2Reliability
If software or programs are used to control the relay or contactor to cut off the power supply, then the control is flexible, but there is a delay in control, weakening the real-time performance
Solution Approach 1:
The patent extracts the control function from the software/program and implements it directly in the hardware circuit through the limit switch. The limit switch directly controls the switch triode to cutoff power supply without software processing delay, achieving immediate real-time response.
Solution Approach 2:
The patent replaces the software-based control system with a direct hardware circuit control system. The limit switch directly controls the power cutoff through the switch triode, eliminating software processing delays and achieving immediate real-time response.
3Speed
If the limit switch directly cuts off the main power supply, then the motor stops immediately, but the feedback signal cannot be provided to the controller
Solution Approach 1:
The patent segments the power cutoff function and feedback signal function into separate circuits. The limit switch controls power cutoff through the switch triode while simultaneously providing position feedback signals to the controller through dedicated feedback circuitry, allowing both functions to operate independently without interference.
Solution Approach 2:
The patent introduces an intermediary feedback circuit that allows the limit switch to simultaneously control power cutoff and provide position feedback. The feedback signal is extracted from the limit switch circuit and transmitted to the controller through a separate path, enabling both power cutoff and feedback without conflict.
4Reliability
If a relay or contactor is used to control the motor, then the power cutoff is reliable, but EMC interference occurs due to electric sparks during switching
Solution Approach 1:
The patent extracts the power cutoff function from the relay/contactor and implements it directly through the limit switch controlling the switch triode. This eliminates the electromagnetic interference source while maintaining reliable power cutoff functionality.
Solution Approach 2:
The patent replaces the relay/contactor-based electromagnetic switching system with a solid-state switch triode controlled directly by the limit switch. This substitution eliminates electric sparks and EMC interference while maintaining reliable power cutoff.
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 system ensures reliable and secure motor control by directly cutting off power supply based on feedback signals, preventing sparks and electromagnetic interference, and avoiding software delays.
Implementation Method 1
a switch circuit section, including at least one switch triode and configured such that a power supply supplies power to a motor by a power supply through the conductive switch triode to drive the motor to output a motion
Implementation Method 2
a limit switch section, including at least one limit switch, configured to be associated with at least one limit position of the motion outputted by the motor, so that the motor generates a feedback signal when outputting the motion to the limit position
Data Source
AI summary
A motor control circuit includes a switch circuit powered by a power supply to drive a motor to output a motion. A switch drive circuit sends a valid drive signal to the switch circuit to drive the motor to output the motion. A limit switch is associated with a position of the motor's motion output, enabling the motor to generate a feedback signal when the motor outputs the motion to the position in a direction. The switch drive circuit receives the feedback signal to cut off power from the power supply to the switch circuit, and the motor stops outputting motion. The motor control circuit feeds from the limit switch back to a controller. When the direction of the motion output by the motor is switched, the power from the power supply to the switch circuit is turned off using the feedback signal.