Motor Control System Current Threshold Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control systems face challenges in continuing operation and preventing unexpected excessive torque when diagnostic results indicate abnormalities, while also managing increased production costs due to complex CPU interactions and high-performance requirements.
Innovation Solution
A motor control system incorporating an overcurrent detection circuit that adjusts current thresholds based on diagnostic results, allowing the system to continue operating by limiting torque when abnormalities are detected, and reducing production costs by avoiding the need for multiple high-performance CPUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the monitoring device stops voltage application when diagnostic result indicates abnormality, then unexpected excessive torque is prevented, but system operation cannot continue and productivity is reduced
Solution Approach 1:
The patent changes the current threshold parameter based on diagnostic results. When abnormality is detected, the current threshold is reduced from a first threshold value to a second threshold value, allowing limited continued operation at reduced torque while still preventing dangerous excessive torque conditions
Solution Approach 2:
The system dynamically adjusts the current threshold in response to diagnostic results. The overcurrent detection circuit switches between different threshold values based on the monitoring device's diagnostic output, enabling adaptive operation mode changes without complete shutdown
2Reliability
If multiple high-performance CPUs are used for mutual monitoring, then diagnostic reliability is improved, but device complexity and production cost increase
Solution Approach 1:
The patent introduces a dedicated monitoring device as an intermediary component that specializes in diagnostic functions. This separate monitoring device communicates with the main CPU through defined interfaces, allowing reliable diagnostics without requiring the main CPU to be overly complex or redundant
Solution Approach 2:
The control system is segmented into a main CPU for motor control and a separate monitoring device for diagnostic functions. This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining diagnostic reliability
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3(A)~3(C)
AI summary
Provided is a motor control system that can suppress p roduction costs and suppress the occurrence of unexpected e xcessive torque, and continues system operation as much as possible even when the diagnosis results of a monitoring de vice are abnormal. A computation device (3) computes a volt age command value indicating the voltage to impose on a moto r (2), and, on the basis of the voltage command value, gener ates a control signal (Spwm) that controls a drive device (5). When the diagnosis results (Rd) of the monitoring device (6) are normal, the computation device (3) computes the vol tage command value in a manner so that the absolute value of the detection value of current flowing to the motor (2) is no greater than a second threshold, and when the diagnosis r esults (Rd) of the monitoring device (6) are abnormal, the c omputation device (3) computes the voltage command value in a manner so that the absolute value of the detection value of current flowing to the motor (2) is no greater than a thi rd threshold that is smaller than the second threshold.