PMSM Stator Fault Monitoring With Sequence-Component Compensation
Solution Overview
Problem
Existing methods for detecting and characterizing inter-turn short circuit faults in permanent magnet synchronous machines (PMSMs) are unreliable, fail to distinguish faults from other issues, and are computationally expensive, leading to inadequate monitoring and potential system stalls.
Innovation Solution
A method using phase voltages and currents to calculate sequence components, determining a fault ratio, and employing an unscented Kalman filter to estimate fault characteristics such as fault current, percentage of shorted turns, and fault loop resistance, while compensating for faults by adjusting current commands based on calculated compensation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If model-based methods are used to detect ISF, then fault detection capability is improved, but reliability deteriorates because resistance in short circuit path and short circuit current are not adequately considered
Solution Approach 1:
The patent transforms the fault detection problem from direct current measurement to sequence component analysis. By changing the parameter representation from time-domain current signals to frequency-domain sequence components (positive, negative, zero sequence), the method achieves reliable fault detection while properly accounting for resistance and current effects that were neglected in previous model-based approaches.
Solution Approach 2:
The patent replaces complex model-based fault detection mechanisms with a signal processing-based approach using sequence component transformation. This substitution eliminates the need for complex state observers and model parameters, providing more reliable detection by directly analyzing the electrical signature of the fault without being affected by model inaccuracies.
2Ease of operation
If signal analysis methods are used to detect ISF, then ease of operation is improved because the method is non-invasive and cost-effective, but measurement precision deteriorates because the method cannot reliably distinguish ISF from other faults
Solution Approach 1:
The patent segments the fault detection problem into distinct sequence component analyses. By separating the analysis into positive sequence, negative sequence, and zero sequence components, the method can precisely identify ISF characteristics that are distinct from other fault types, thereby improving measurement precision while maintaining the simplicity of signal-based approaches.
Solution Approach 2:
The patent introduces sequence components as an intermediary between raw current signals and fault diagnosis. This intermediary transformation layer extracts meaningful fault characteristics from the current spectra, enabling precise distinction between ISF and other faults while keeping the method non-invasive and computationally simple.
3Measurement precision
If AI-based techniques are used to detect and estimate fault severity, then measurement precision is improved, but device complexity worsens because the methods are computationally expensive and difficult to implement
Solution Approach 1:
The patent replaces expensive and complex AI-based fault estimation with a simple, computationally efficient analytical method based on sequence components. This approach provides sufficient precision for fault severity estimation without requiring heavy computational resources, making it suitable for real-time implementation in cost-effective hardware.
Solution Approach 2:
The patent extracts only the essential fault characteristics needed for diagnosis by focusing on specific sequence component relationships. This extraction approach eliminates the need for complex AI algorithms while maintaining measurement precision, as the sequence component analysis directly reveals fault severity information without requiring comprehensive pattern recognition.
Data Source
AI summary
A method and system for online monitoring and compensation of inter-turn short circuit faults (ISF) in windings of electric machines, such as permanent magnet synchronous motors is provided. A method for characterizing an ISF in a winding of an electric machine comprises: measuring phase voltages and currents; calculating sequence components of the electric machine based on the phase voltages and currents; determining a ratio between a percentage of shorted turns in the winding and a fault loop resistance based on the sequence components of the electric machine; and estimating characteristics of the inter-turn short circuit fault using an unscented Kalman filter. The characteristics include at least one of: a fault current, the percentage of shorted turns, or the fault loop resistance. A method for compensation an ISF in a winding of an electric machine comprises compensating the fault current based on the compensation current estimated from an unscented Kalman filter.