Synchronous Machine Rotor Magnet Detection via Voltage Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting the presence of a permanent magnet in synchronous machines are not generic and require specific algorithm modifications and parameter tuning, often necessitating the use of rotor position feedback devices, which can be costly or unreliable, and are not suitable for standstill operations or machines with varying saliency ratios.
Innovation Solution
A method involving the injection of a voltage waveform into the stator windings of a synchronous machine, transforming phase currents into a rotor reference frame, and analyzing harmonic distortions in periodic waveforms to determine the presence and orientation of a permanent magnet, without prior knowledge of the machine type or the need for feedback devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency signal injection methods are used to improve measurement precision of rotor position and magnet polarity, then measurement precision is improved, but device complexity increases due to additional signal processing techniques and waveform analysis requirements
Solution Approach 1:
The patent extracts and analyzes only the essential features of the current response waveform - specifically the polarity of current samples taken at fixed points during voltage pulse application. By focusing only on these critical samples rather than performing comprehensive waveform analysis, the method achieves accurate rotor position and magnet polarity detection while significantly reducing signal processing complexity.
Solution Approach 2:
The patent uses simple, disposable voltage pulses applied to stator windings to excite the machine, rather than requiring complex continuous high-frequency signal injection systems. These simple excitation pulses are sufficient to generate measurable current responses that contain all necessary information for rotor position and magnet polarity identification.
2Measurement precision
If literature-specific identification algorithms are applied to particular electrical machines to achieve accurate rotor position identification, then measurement precision is improved, but adaptability decreases when applied to different electrical machine types
Solution Approach 1:
The patent develops a universal identification algorithm based on fundamental electromagnetic principles that works across different electrical machine types (synchronous machines, induction machines, permanent magnet machines). The method uses basic voltage pulse application and current sampling that can be applied to any machine with stator windings, eliminating the need for machine-specific algorithm modifications while maintaining accurate rotor position identification.
3Reliability
If rotor position feedback devices are used to improve reliability of drive operation, then reliability is improved, but cost increases and the devices may negatively influence drive reliability
Solution Approach 1:
The patent enables the electrical machine to identify its own rotor position and magnet polarity information through self-excitation using applied voltage pulses and analysis of resulting current responses. This self-identification capability eliminates the need for external rotor position feedback devices (encoders, resolvers, Hall sensors), reducing system complexity and cost while maintaining reliable operation through accurate initial rotor position determination.
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 robust initial electrical rotor position identification and permanent magnet detection in various synchronous machines, including those with nonlinear characteristics, without requiring regulation or rotor movement, and is independent of machine type, facilitating standstill operations.
Implementation Method 1
providing an injection of a voltage waveform to stator windings of the synchronous machine, obtaining a measurement of two phase currents in the stator winding due to the injection of the voltage waveform
Implementation Method 2
performing a frequency analysis of a first spectrum of a first periodic waveform and a second spectrum of a second periodic waveform, and determining whether a permanent magnet is present in the synchronous machine based on the first spectrum and on the second spectrum
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present disclosure relates to a method of detecting the presence of a permanent magnet of a rotor of a synchronous machine, wherein the method comprises: providing (S2) an injection of a voltage waveform to the stator windings of the synchronous machine, obtaining (S3) a measurement of two phase currents in the stator winding generated due to the injection of the voltage waveform, transforming (S4) the two phase currents to a rotor reference frame to obtain a current waveform in the rotor reference frame, sampling (S5) the positive portion of a cycle of the current waveform to obtain sampled positive portion values and the negative portion of a cycle of the current waveform to obtain sampled negative portion values, constructing (S6) a first periodic waveform by using the sampled positive portion values and a second periodic waveform by using the sampled negative portion values, performing (S7) a frequency analysis of a first spectrum of the first periodic waveform and of a second spectrum of the second periodic waveform, and determining (S8) whether a permanent magnet is present in the synchronous machine based on the first spectrum and on the second spectrum.