Elevator Motor Current Monitoring for Stator Short Detection
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Solution Overview
Problem
Elevator motor failures, such as turn-to-turn short circuits in stator coils, can lead to sudden and unpredictable stalls, posing safety hazards, especially when passengers are using the elevator, as existing technologies lack effective real-time monitoring and response mechanisms.
Innovation Solution
A fault monitoring device and method that determines the occurrence of turn-to-turn short circuits in elevator motors by analyzing stator coil current components at specific characteristic frequencies, using a processor and computer program to identify faults and send alerts to control systems to prevent accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time monitoring of stator coil current is implemented to detect turn-to-turn short circuits, then safety and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex hardware monitoring systems with a software-based solution that uses Fast Fourier Transform (FFT) algorithms to analyze current signals. The processor executes monitoring programs to detect fault characteristics, substituting mechanical/electrical monitoring complexity with computational methods that achieve the same safety monitoring function with simpler hardware requirements.
Solution Approach 2:
The monitoring device is designed to perform multiple functions: it monitors stator coil current, performs FFT analysis to extract frequency components, detects turn-to-turn short circuit faults, and can control elevator operation. This multi-functional integration reduces the need for separate dedicated monitoring hardware, thereby reducing overall device complexity while maintaining high reliability.
2Measurement precision
If complex signal analysis is performed to accurately detect faults, then measurement precision is improved, but processing time and computational load increase
Solution Approach 1:
The patent extracts only the relevant frequency components from the stator coil current signal using FFT analysis. Instead of analyzing the entire signal spectrum, it specifically identifies and examines components at characteristic frequencies (such as 2n times the fundamental frequency) that indicate turn-to-turn short circuits. This selective extraction maintains high detection precision while reducing processing time by focusing computational resources on critical frequency bands.
Solution Approach 2:
The monitoring system changes the parameter being analyzed from time-domain current waveforms to frequency-domain components. By transforming the analysis domain through FFT and focusing on specific frequency characteristics, the system achieves precise fault detection with reduced processing requirements compared to analyzing raw time-domain signals for fault indicators.
3Reliability
If continuous monitoring is performed to prevent sudden stalls, then reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic monitoring of stator coil current at characteristic frequencies rather than continuous full-signal analysis. The system periodically executes FFT analysis to extract frequency components and compares them against threshold values, enabling continuous fault detection capability while reducing energy consumption by performing computations at intervals rather than continuously processing all signal data.
Data Source
AI summary
A fault monitoring device and method for elevator motor and computer-readable storage medium on which computer programs for implementing the method are stored. A fault monitoring device for an elevator motor, includes: a memory; a processor coupled with the memory; and a computer program stored on the memory and running on the processor, the running of the computer program causes: A. determining one or more components of a stator coil current at one or more characteristic frequencies from a measurement of the stator coil current of the elevator motor; and B. determining, based on the one or more components, whether a fault of turn-to-turn short circuit occurs in the stator coil.