Magnetic Gap Estimation From No-Load Line Voltage Harmonics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for estimating eccentricity in rotating electric machines require current sensors or current loads, leading to device upsizing and are not suitable for systems without current sensors, and measuring voltage at a connection-wire neutral point is difficult during manufacturing processes.
Innovation Solution
A magnetic gap length estimating device that acquires no-load-induced line-to-line voltage and uses spectrum and frequency analysis to estimate magnetic gap length without needing current sensors or measuring connection-wire neutral point voltage, utilizing a voltage acquiring unit, spectrum analysis unit, frequency analysis unit, and estimating-and-calculating unit to determine magnetic gap length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods using current sensors or current loads are employed to estimate eccentricity, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the essential measurement information (line-to-line voltage) from the complex measurement systems, eliminating the need for current sensors and current loads. By focusing on voltage measurement alone, the system achieves eccentricity detection without the bulky hardware required by conventional methods.
Solution Approach 2:
The patent replaces mechanical/electrical measurement systems (current sensors, current loads) with an electrical measurement system (voltage measurement). This substitution eliminates the need for physical current sensing hardware while maintaining measurement capability through voltage-based indirect measurement.
2Measurement precision
If voltage at connection-wire neutral point is measured to estimate eccentricity, then measurement precision is improved, but ease of operation deteriorates due to difficulty in accessing neutral point during manufacturing
Solution Approach 1:
The patent uses line-to-line voltage as an intermediary measurement that provides indirect access to the magnetic gap information. Instead of directly measuring at the neutral point (which is inaccessible), the line-to-line voltage serves as a mediator that can be easily measured while still conveying the required diagnostic information.
3Measurement precision
If current sensors are used for eccentricity detection in driving systems, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent enables the driving system to perform self-diagnosis using existing voltage measurement infrastructure. The system uses line-to-line voltage measurements that are already available in the driving system to detect eccentricity, eliminating the need for additional current sensing hardware and enabling the system to monitor its own health.
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
Enables accurate estimation of magnetic gap length without current sensors or neutral point voltage measurement, reducing device size and complexity, and allowing for eccentricity detection during manufacturing.
Implementation Method 1
a no-load-induced line-to-line voltage induced between the connection wires
Data Source
AI summary
Provided is a magnetic gap length estimating device in which neither a current sensor nor a current load is necessary, and a voltage at a connection-wire neutral point does not need to be measured. A magnetic gap length estimating device for estimating a magnetic gap length in an M-group N-phase rotating electric machine to be driven by an inverter includes: a voltage acquiring unit which acquires a no-load-induced line-to-line voltage induced under no load; and a magnetic gap estimating unit. The magnetic gap estimating unit includes: a spectrum analysis unit which converts the no-load-induced line-to-line voltage acquired by the voltage acquiring unit into amplitudes and phases for respective frequencies; a frequency analysis unit which extracts amplitudes and phases of a fundamental wave component and an Nth-order harmonic component of the no-load-induced line-to-line voltage; and an estimating-and-calculating unit which estimates the magnetic gap length.