Current Sensor Malfunction Detection Using Sum and Difference Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting current sensor malfunctions in multi-phase machines require three current sensors, which is costly and inefficient, whereas it is desirable to detect malfunctions using only two current sensors for feedback control.
Innovation Solution
A method that uses two current sensors to obtain current signals and a position signal to determine if a malfunction occurred by calculating a sum signal and a difference signal at specific angular positions of the rotor, and comparing an index value derived from these signals with a predefined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three current sensors are used for malfunction detection, then detection reliability is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts the malfunction detection function from a dedicated third current sensor and implements it instead through mathematical processing of signals from the two existing current sensors. By calculating sum and difference signals and analyzing their characteristics at specific rotor positions, the system achieves malfunction detection without adding extra hardware sensors.
Solution Approach 2:
The two current sensors serve dual purposes: they provide current feedback for motor control and simultaneously enable malfunction detection through signal processing. The same sensors that measure phase currents for control algorithms also generate sum and difference signals that reveal sensor malfunctions, eliminating the need for dedicated detection hardware.
2Measurement precision
If three current sensors are used for malfunction detection, then detection accuracy is improved, but cost increases
Solution Approach 1:
The patent extracts the malfunction detection capability from physical hardware (third sensor) and implements it through mathematical operations on existing sensor signals. The sum and difference signal calculations, combined with threshold comparisons at specific rotor positions, provide accurate malfunction detection without requiring additional sensors.
Solution Approach 2:
The patent transforms the detection approach by changing from direct physical measurement (third sensor) to mathematical parameter analysis (sum and difference signal characteristics). By analyzing the magnitude and zero-crossing points of processed signals at specific rotor positions, the system achieves accurate malfunction detection through parameter transformation rather than additional hardware.
3Device complexity
If two current sensors are used, then cost and simplicity are improved, but malfunction detection capability deteriorates
Solution Approach 1:
The patent introduces mathematical processing (sum and difference signal calculations) as an intermediary between the two current sensors and the malfunction detection function. This intermediary transformation enables the system to extract malfunction information from the limited sensor data, bridging the gap between reduced hardware and maintained detection capability.
Solution Approach 2:
The system continuously monitors the sum and difference signals from the two current sensors and uses feedback from their characteristics (magnitude, zero-crossing points) to detect malfunctions. This feedback mechanism allows the system to adaptively identify sensor failures by comparing processed signal characteristics against expected behavior at specific rotor positions.
Data Source
AI summary
A machine control system and a method of detecting a current sensor malfunction include obtaining a first current signal from a first current sensor corresponding with a first phase of a multi-phase machine, obtaining a second current signal from a second current sensor corresponding with a second phase of the multi-phase machine, and obtaining a position signal indicating an angular position of a rotor of the multi-phase machine corresponding with values of the first current signal and the second current signal. A determination is made of whether the current sensor malfunction occurred in the first current sensor or the second current sensor based only on the values of the first current signal and the second current signal at four of the angular positions of the rotor.