• Smart Structures and Systems
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• v.29 no.6
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• pp.799-805
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• 2022

Permanent magnet synchronous motors (PMSMs) are widely used in systems requiring high control precision, efficiency, and reliability. Predicting the remaining useful life (RUL) with health monitoring of PMSMs prevents catastrophic failure and ensures reliable operation of system. In this study, a model-based method for predicting the RUL of PMSMs using phase current and vibration signals is proposed. The proposed method includes feature selection and RUL prediction based on a particle filter with a degradation model. The Paris-Erdogan model describing micro fatigue crack propagation is used as the degradation model. An experimental set-up to conduct accelerated life test, capable of monitoring various signals was designed in this study. Phase current and vibration data obtained from an accelerated life test of the PMSMs were used to verify the proposed approach. Features extracted from the data were clustered based on monotonicity and correlation clustering, respectively. The results identify the effectiveness of using the current data in predicting the RUL of PMSMs.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1614-1622
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• 2018

The research related to fault diagnosis in permanent magnet synchronous motors (PMSMs) has attracted considerable attention in recent years because various faults such as permanent magnet demagnetization and short-circuited turns can occur and result in unexpected failure of motor related system. Several conventional current and back electromotive force (BEMF) analysis techniques were proposed to detect certain faults in PMSMs; however, they generally deal with a single fault only. On the contrary, cases of multiple faults are common in PMSMs. We propose a fault diagnosis method for PMSMs with single and multiple combined faults. Our method uses three phase BEMF voltages based on the fast Fourier transform (FFT), support vector machine(SVM), and visualization tools for identifying fault types and severities in PMSMs. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) are used to visualize the high-dimensional data into two-dimensional space. Experimental results show good visualization performance and high classification accuracy to identify fault types and severities for single and multiple faults in PMSMs.

• The Journal of the Korean dental association
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• v.50 no.4
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• pp.203-210
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• 2012

Objective: The aim of this study was to investigate the incidence of the C-shaped canal of permanent mandibular second molar (PMSM) in Korean sub-population using Cone-Beam CT (CBCT) data and analyze the types of C-shaped canal. Materials & Methods: The protocol for this study was approved by the Institutional Review Board at the Pusan National University Hospital (E-2011039). Among the CBCT images taken of patients who visited the St. Bennedict Dental Hospital (Busan, Korea) from May 2008 to April 2011 for implant surgery and surgical removal of impacted teeth, high-quality CBCTs from 705 patients (361 male and 342 female) were screened and 607 PMSMs of 383 patients were evaluated retrospectively. All PMSMs were anatomically analyzed in detail by using image viewer software (EasyDent; Vatech). PMSMs were evaluated in the axial plane to investigate the shape of root and canals. The C-shaped canals were classified into five types. The total incidence, gender ratio, bilateral and unilateral appearance. and the correlation between right-side and left-side occurrences of C-shaped PMSMs were computed and compared statistically using the chi-square test. Results: Among the 607 PMSMs of 383 CBCTs of 187 females and 196 males, 198 PMSMs(32.6%) had C-shaped root and 158 PMSMs(26.0%) had C-shaped canals. The shape of C-shaped root canals at the furcalion level did not have significant change at the level of mid root (P<0.0001). Female had more prevalence of C-shaped root canals than male (P<0.0001). The prevalence of bilateral occurrence of C-shaped root canals was higher than unilateral occurrence. Conclusions: The occurrence of C-shaped PMSMs among a Korean population was 32.6% and was higher than other countries and ethnicities. Understanding the prevalence of PMSMs with a C-shaped root and/or canal in a Korean population may be useful for successful endodontic treatments.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.403-408
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• 2014

If it were possible to control four sets of PMSMs in place of induction motors by using one inverter, we could attain efficient driving trains. In this paper, a method for controlling three sets of PMSMs with one inverter is shown. Additionally, this shows the method to control four sets of PMSMs with one inverter and the results of a simulation with the proposed method.

• ETRI Journal
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• v.37 no.6
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• pp.1176-1187
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• 2015

This work proposes a highly efficient sensorless motor driver chip for various permanent-magnet synchronous motors (PMSMs) in a wide power range. The motor driver chip is composed of two important parts. The digital part is a sensorless controller consisting mainly of an angle estimation block and a speed control block. The analog part consists of a gate driver, which is able to sense the phase current of a motor. The sensorless algorithms adapted in this paper include a sliding mode observer (SMO) method that has high robust characteristics regarding parameter variations of PMSMs. Fabricated SMO chips detect back electromotive force signals. Furthermore, motor current-sensing blocks are included with a 10-bit successive approximation analog-to-digital converter and various gain current amplifiers for proper sensorless operations. Through a fabricated SMO chip, we were able to demonstrate rated powers of 32 W, 200 W, and 1,500 W.

• Smart Structures and Systems
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• v.29 no.6
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• pp.785-790
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• 2022

Condition monitoring of permanent magnet synchronous motors (PMSMs) and detecting faults such as eccentricity and demagnetization are essential for ensuring system reliability. Motor current signal analysis is the most commonly used precursor for detecting faults in the PMSM drive system. However, the current signature responds sensitively to the load and temperature of the motor, thereby making it difficult to monitor faults in real- applications. Therefore, in this study, a condition monitoring methodology that detects motor faults, including their classification with standstill conditions, is proposed. The objective is to detect and classify faults of PMSMs by using programmable inverter without additional sensors and systems for detection. Both DC and AC were applied through the d-axis of a three-phase motor, and the change in incremental inductance was investigated to detect and classify faults. Simulation with finite element analysis and experiments were performed on PMSMs in healthy conditions as well as with eccentricity and demagnetization faults. Based on the results obtained from experiments, the proposed method was confirmed to detect and classify types of faults, including their severity.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.240-246
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• 2018

In this paper, a sensorless V/f control based on maximum torque per ampere (MTPA) operation for PMSMs is proposed. Given that the MTPA operation is not considered in the conventional sensorless V/f control, efficient PMSM drives cannot be achieved. Therefore, this paper proposes an improved technique based on the d-axis current control to enable the MTPA operation in the V/f control for PMSMs. A stabilization technique is also proposed to improve the dynamic characteristics and stability against load variation. The effectiveness of the proposed technique is verified by conducting experiments with a 250 W SPMSM for driving a blower.

• Journal of Industrial Technology
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• v.34
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• pp.15-20
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• 2014

Recently, PMSMs(Permanent Magnet Synchronous Motors) have become increasingly popular in various high-performance motor drive applications. However, the high-performance drive of PMSMs needs a position sensor such as a resolver, which increases not only the price of the system but also reduces the system reliability. This paper is on the implementation of sensorless control of a SPMSM, which drives a fan for cooling in appliances. In this paper, the rotor position for high-performance drive of a SPMSM is derived from back electromotive force (EMF) information proportional to the rotor speed. Also, the initial rotor position information for start-up is estimated from a saturation phenomenon of inductance. The validity of the proposed sensorless drives was confirmed by the experiment on the SPMSM drive systems for cooling fans of refrigerators and laptop computers.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.125-132
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• 2002

PMSMS (permanent magnet synchronous motors) are widely used in industrial applications and home appliances because of their high torque to inertia ratio, superior power density, and high efficiency. For high performance control, accurate informations about the rotor position is essential. Sensorless algorithms have lately been studied extensively due to the high cost of position sensors and their low reliability in harsh environments. A novel position sensorless speed control for PMSMs uses indirect flux estimation and is presented in this paper. Rotor position and angular velocity are estimated by the proposed indirect flux estimation. Linkage flux and magnetic field flux are calculated by the voltage equations and the measured phase current without any integration. Instead of linkage flux calculation with integral operation, indirect flux and differential magnetic field are used for the estimation of rotor position. A proper rejection technique fur current noise effect in the calculation of differential linkage flux is introduced. The proposed indirect flux detecting method is free from the integral rounding error and linkage flux drift problem, because differential linkage flux can be calculated without any integral operation. Furthermore, electrical parameters of the PMSM can be measured by the proposed TCM (time compression method) for soft starting and precise estimation of rotor position. The position estimator uses accurate electrical parameters that are obtained from the proposed TCM at starting strategy. In the operating region, a proper compensation method fur temperature effect can compensate fir the estimation error from the variation of electrical parameters. The proposed novel position sensorless speed control scheme is verified by the experimental results.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2173-2181
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• 2016

Permanent magnet synchronous motors (PMSMs) have higher torque and superior output power per volume than other types of AC motors. They are commonly used for applications that require a large output power and a wide range of speed. For precise control of PMSMs, knowing the accurate position of the rotor is essential, and normally position sensors such as a resolver or an encoder are employed. On the other hand, the position sensors make the driving system expensive and unstable if the attached sensor malfunctions. Therefore, sensorless algorithms are widely researched nowadays, to reduce the cost and cope with sensor failure. This paper proposes a sensorless algorithm that can be applied to a wide range of speed. The proposed method features a robust operation at low-speed as well as high-speed ranges by employing a gain adjustment scheme and intermittent voltage pulse injection method. In the proposed scheme the position estimation gain is tuned by a closed loop manner to have stable operation in tough driving environment. The proposed algorithm is fully verified by various experiments done with a 1 kW outer rotor-type PMSM.