Motor Speed System Fault Detection via Test Signal Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for checking the speed system of motor-driven devices are limited in their ability to distinguish between hardware defects and signal issues, particularly when the device is at a standstill or in a soft-start phase, and do not effectively evaluate motor current signals to diagnose errors.
Innovation Solution
A method that involves switching on the motor-driven device, checking for a speed signal, outputting a test signal if none is detected, processing it through the rotational speed detection device, and detecting errors during the soft start phase, using both hardware and software approaches to differentiate between hardware defects and signal issues, and evaluating motor current signals to determine fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods are used to check the speed system, then the device can be operated, but the ability to distinguish between hardware defects and signal issues is limited
Solution Approach 1:
The method performs preliminary testing actions by outputting test signals through the speed sensing device before actual operation to proactively identify potential faults. The control unit outputs test signals via its output in response to detecting absent speed signals, enabling early fault detection before the device is fully operational.
Solution Approach 2:
The control unit serves as an intermediary by routing test signals through the speed sensing device and evaluating the processed signals. This intermediary approach allows the system to indirectly assess the functionality of the speed sensing device and distinguish between hardware defects and signal issues without directly testing each component separately.
2Reliability
If the device is checked during standstill or soft-start phase, then more fault conditions can be detected, but existing methods do not effectively evaluate motor current signals
Solution Approach 1:
The method merges speed signal evaluation with motor current signal evaluation into a unified diagnostic approach. The control unit simultaneously processes both speed signals from the speed sensing device and motor current signals to comprehensively assess system health during standstill and soft-start phases, enabling more reliable fault detection.
Solution Approach 2:
The system implements feedback by continuously monitoring both speed signals and motor current signals, and using this feedback information to detect faults. When the control unit detects absent or abnormal speed signals, it outputs test signals and evaluates the combined feedback from both signal sources to determine the nature of the fault.
3Measurement precision
If a test signal is output when no speed signal is detected, then the speed sensing device can be verified, but the system requires both hardware and software approaches
Solution Approach 1:
The control unit is designed with multi-functionality, serving both as the primary controller for device operation and as a test signal generator for diagnostic purposes. This universal approach allows the same control unit to perform both operational control and fault detection functions, reducing the need for separate dedicated testing hardware.
Data Source
Figure 1a~2
AI summary
A method for checking the speed control system of a motor-driven device is proposed. According to the first aspect, if a speed signal is missing, a test signal is sent via the speed control system by a control device, with the test signal expected at an input of the control device. If the test signal is not detected, a fault in the speed control system is identified. After a start-up phase, it is checked whether a speed signal is present as expected. If this is not the case, a fault in the speed control system is detected. Similarly, if the motor current does not exceed a certain value indicating stalling, but no speed signal is detected, a fault is also inferred.