Showing papers by "Jin Hur published in 2016"

Detection of Inter-Turn and Dynamic Eccentricity Faults Using Stator Current Frequency Pattern in IPM-Type BLDC Motors

Abstract: This paper propose a fault detection algorithm for stator inter-turn faults (SITFs), dynamic eccentricity faults (DEFs), and hybrid faults (a combination of SITF and DEF) in a permanent magnet (PM) brushless dc motor. We analyzed specific frequency patterns of the stator input current to diagnosis and distinguish the fault types. First, we developed a two-dimensional (2-D) finite element method (FEM) program using a system matrix, and then we confirmed additional specific frequency patterns of the input current by a fast Fourier transform. Finally, specific frequency patterns for each fault type were verified by experimental results.

New Equivalent Circuit of the IPM-Type BLDC Motor for Calculation of Shaft Voltage by Considering Electric and Magnetic Fields

Abstract: Fast switching and common-mode voltage of the space vector pulse-width modulation inverter output create several parasitic capacitances according to the geometry of the motor. The windings emit the electric and magnetic flux inside of the motor. They create capacitance links and electromotive force (EMF) in the shaft, respectively. Those capacitance links and EMF generate a current through two bearings of the shaft and directly reduces the bearing lifetime. In this study, we propose a new design of equivalent circuit, taking into account all parasitic capacitor components.

A Novel Proposal to Improve Reliability of Spoke-Type BLDC Motor Using Ferrite Permanent Magnet

Abstract: This paper proposes a novel proposal to improve reliability of a spoke-type brushless direct current (BLDC) motor using ferrite permanent magnets (Fe-PMs) through a new design. First, the design process for a neodymium permanent magnet (Nd-PM) free spoke-type BLDC motor without assistant permanent magnets (PMs) is presented. The proposed motor is designed by taking into account the demagnetization phenomenon. Second, the effect of the armature reaction on the PMs is analyzed by using the finite element method (FEM) in order to evaluate the robustness of the proposed motor with Fe-PM. In addition, another proposal to avoid the demagnetization phenomenon is suggested. Finally, a prototype motor is manufactured based on the proposed motor. The output characteristics of prototype motor and the demagnetization phenomenon are verified through an experiment.

Mitigation method of the shaft voltage according to parasitic capacitance of the PMSM

Abstract: In this study, we propose the mitigation method of a shaft voltage according to change in parasitic capacitances of a permanent magnet synchronous motor (PMSM). First, we designed the equivalent circuit taking into account all parasitic capacitances. Then, we deducted that rotor-to-winding and stator-to-rotor capacitances mainly affect the shaft voltage. The stator-to-rotor capacitance depends on the air-gap length, which directly affects output torque characteristics of the motor. In case of the rotor-to-winding capacitance, it depends on the distance from the rotor to winding, which have effects on torque ripple, but it doesn't affect average torque of the motor. Thus, rotor-to-winding capacitance is determined as a variable for mitigation of the shaft voltage. According to change in the rotor-to-winding capacitance, we obtained and compared the results of the shaft voltage, average torque, and torque ripple.

Electrical Characteristic Analysis According to Contact Resistance Between Turns of HTS Coil

Abstract: This paper presents our analysis of the output characteristics of a high-temperature superconductor (HTS) coil depending on the turn-to-turn contact resistance. Important design factors were investigated by taking into account the turn-to-turn contact resistance based on the analysis results. Analyses were performed on five self-fabricated coil models with different turn-to-turn contact resistances. To consider only the turn-to-turn contact resistance, we used a first-generation HTS BSCCO wire with simpler architecture and mechanical properties than the second-generation HTS wire. From this study, it was confirmed by experiment that as the turn-to-turn contact resistance decreases, the electrical stability increases but the output efficiency decreases compared with the input.

Characteristics of irreversible demagnetization in accordance with phase advance angle in IPM-type BLDC motor

Abstract: Advance angle control of phase current is frequently used for high efficiency of machine. However, advance angel control can generate irreversible demagnetization of permanent magnet brushless dc motor. In this paper, irreversible demagnetization characteristics therefore are analyzed in accordance with advance angle of phase current in inner permanent magnet-type brushless dc motor.

Demagnetization Detection for IPM-type BLDCMs According to Irreversible Demagnetization Patterns and Pole-Slot Coefficients

Abstract: This paper proposes a method for detecting irreversible demagnetization using the harmonic analysis of back electromotive force (BEMF) in interior permanent magnet-type brushless DC motors. First, demagnetization patterns, such as equality, inequality, and weighted demagnetizations, are defined and classified by considering the possibility of demagnetization resulting from motor operating characteristics. Second, an available diagnostic model for the harmonic analysis of BEMFs is defined according to pole–slot coefficients because the characteristics of BEMFs under demagnetization conditions are affected by the combination of poles and slots. Third, BEMFs and their harmonic components under normal and demagnetization conditions are analyzed through simulation and experiment to verify the proposed demagnetization detection technique.

Reduction method based on looped slot wedges for end to end shaft voltage in inverter driven IPM motor

Abstract: Common mode voltage of the inverter output create a leakage current in the stator. It creates a net magnetic flux link with the shaft and induces an electromotive force (EMF) in between the two ends of the rotor. This EMF generates a current through two bearings and reduces its lifetime. In this study, we propose a frequency selective low impedance path to dissipate the EMF in the shaft. Finally, end to end shaft voltage can be reduced by dissipate the EMF in the rotor.