Hyeyun Jeong

Demagnetization Fault Diagnosis of a PMSM Based on Structure Analysis of Motor Inductance

A demagnetization fault in a permanent-magnet synchronous machine (PMSM) degrades performance and energy efficiency. The demagnetization fault causes flux-density difference and changes the PMSM inductances. Such varying parameters make it difficult to detect and diagnose the exact severity of a demagnetization fault. In this paper, we suggest a use of structural analysis of the PMSMs to diagnose the demagnetization fault. We can calculate varying inductances and consider the magnetic saturation effect with varying flux linkages of the machine. Combination of the proposed technique with the least-square (LS) method shows better results than the conventional methods in the estimation of flux linkages in the PMSMs with the demagnetization fault. Experimental results demonstrate that the proposed method works well both in the tracking of varying inductances and the diagnosis of the demagnetization fault.

Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation

This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq) of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties.

An Early Stage Interturn Fault Diagnosis of PMSMs by Using Negative-Sequence Components

This paper proposes an early stage interturn short-circuit fault (ISCF) diagnosis method for permanent magnet synchronous machines. A fault indicator is suggested based on a new theoretical analysis of the relationship between the fault current and the rotor speed. The fault indicator is shown to be robust to the rotor speed changes in slight ISCFs. It is calculated by introducing negative-sequence components (NSCs). It is shown that the fault indicator using NSCs can diagnose slighter ISCFs than that using zero-sequence components. Experimental results demonstrate the effectiveness of the proposed method for diagnosing early stage ISCFs with a small number of short-circuited turns and low fault current.

Interturn short fault diagnosis of a PMSM using voltage residual components

This paper proposes a fault diagnosis method for a permanent magnet synchronous machine (PMSM) with an interturn short fault. The Interturn short fault degrades motors performance and may lead to additional faults such as a demagnetization fault. In this paper, we suggest a diagnosis of the interturn short fault in PMSM using a Least Square method with voltage residual components. A rearranged fault model is based on a conventional interturn short fault model and focused on a faulty winding. We also propose a fault index based on the rearranged model. Simulation results from a Maxwell, which is a finite element analysis (FEA) tool, demonstrate that the proposed method works well in various fault conditions.

Interturn Short Fault Diagnosis in a PMSM by Voltage and Current Residual Analysis With the Faulty Winding Model

As interturn short fault (ISF) in a permanent-magnet synchronous machine (PMSM) degrades its energy efficiency and may cause other problems, accurate fault diagnosis for the PMSMs is necessary. In this paper, we present a method that uses voltage and current residual components to diagnose the phase and the severity of the ISF in PMSMs. A faulty-winding model (FWM) is introduced to analyze the fault; the model describes a relationship between the voltage decrease of the faulty winding to the characteristics of the fault such as a fault resistance and a fault turn ratio. Based on the model, we suggest a fault index (FI) that shows the severity of the ISF. As the ISF induces residual components to both voltage and current, the proposed method utilized those components with the FWM. A least squares (LS) method is used to estimate the FI and to diagnose the ISF of PMSMs. Experimental results demonstrate that the proposed method diagnose the ISF effectively.

Demagnetization Fault Diagnosis in IPMSM Using Linear Interpolation

This paper proposes a demagnetization fault diagnosis method for interior permanent magnet synchronous motors(IPMSMs). In particular, a demagnetization fault is one of the most frequent electrical faults in IPMSMs. This paper proposes an estimation method for permanent magnet flux. The method is based on linear interpolation. The effectiveness of the proposed method for diagnose demagnetization faults is verified through various operating conditions by finite element simulation.

Interturn Fault Diagnosis in Interior Permanent Magnet Synchronous Motors Using Negative-Sequence Impedance

Fault diagnosis is important due to the increasing demand of using interior permanent magnet synchronous machines (IPMSMs). In particular, an interturn fault is one of the most frequent electrical faults in IPMSMs. This paper proposes a fault indicator for diagnosis of interturn faults in IPMSMs. The fault indicator is developed by negative-sequence impedance. The effectiveness of the fault indicator to diagnose interturn faults was verified through various fault conditions.

Interturn short circuit fault detection of permanent magnet synchronous motors based on positive- and negative-sequence signatures

This paper proposes a novel fault diagnosis method based on positive- and negative-sequence signatures in permanent magnet synchronous motors (PMSMs) with an interturn short circuit fault (ISCF). The proposed method diagnoses the ISCF severity and slight ISCFs only by the voltage and the current signals without the rotational angle and the model parameters such as the stator resistance and the inductances. The proposed fault indicator to diagnose ISCFs is developed by using the phase difference between positive-sequence current and positive-sequence voltage, and the magnitude of negative-sequence voltage over negative-sequence current. Experimental results demonstrate the effectiveness of the proposed fault indicator for diagnosing the ISCF severity and slight ISCFs.

Inter-turn short fault diagnosis of permanent magnet synchronous machines using negative sequence components

Recently, fault diagnosis is becoming more important due to the increasing demand of using permanent magnet synchronous machines (PMSMs). In particular, inter-turn short fault (ISF) is one of the most frequent electrical faults in PMSMs. In this paper, we propose a method using negative sequence components (NSC). The NSC method not only calculates a fault indicator that is not easily affected by the changes of the rotor speed, but also diagnoses the degree of failure for PMSMs with the ISF more accurately. In addition, the method can be applied to PMSMs with weak ISF or low rotational speed. The effectiveness of the NSC method to diagnose the ISF was verified through various operating conditions.