Jin-Hyung Yoo

Irreversible Demagnetization Fault Diagnosis of Permanent Magnet Synchronous Motor for Electric Vehicle

Recently, researchers have an interest on the electric vehicle because it is more eco-friendly and efficient than gas vehicle. Instead of a gas engine, the electric vehicle has a motor for propulsion. The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and torque per weight than other types of motor. When the irreversible demagnetization is occurred, users can be expose to high risk of accident by the fault operation of motor. Because of this, the irreversible demagnetization of permanent magnet should be detected by using any kinds of method to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result of locked rotor test is proposed. Base on short measurement time, the proposed diagnosis method aims to detect the demagnetization fault when the electric vehicle is at a complete standstill. The proposed method is verified by using the finite element analysis.

Design on notch structure of stator tooth to reduce of cogging torque of single-phase BLDC motor

This paper proposes the design method on the notch structure of stator tooth to reduce the cogging torque of the single-phase brushless Direct Current (BLDC) Motor. The single phase BLDC motors generates the dead-point causing a starting failure. This problem is solved by using an asymmetric air-gap structure. However, the asymmetric air-gap structure increases the cogging torque causing a noise and vibration of BLDC motor. Therefore, the reduction of cogging torque is essential to improve the performance of BLDC motor. This study for reducing the cogging torque of BLDC motors applies to notch structure of stator because of ease of application and low cost. In this paper, Availability on reduction of cogging torque of the asymmetric notch is proved by using two-notches. Then, the reduction of cogging torque is proved by using the finite element analysis(FEA).

A study on thermal characteristics analysis model of high frequency switching transformer

Recently, interest has been shown in research on the module-integrated converter (MIC) in small-scale photovoltaic (PV) generation. In an MIC, the voltage boosting high frequency transformer should be designed to be compact in size and have high efficiency. In response to the need to satisfy these requirements, this paper presents a coupled electromagnetic analysis model of a transformer connected with a high frequency switching DC-DC converter circuit while considering thermal characteristics due to the copper and core losses. A design optimization procedure for high efficiency is also presented using this design analysis method, and it is verified by the experimental result.

Design optimization of high frequency transformer with controlled leakage inductance for current fed dual active bridge converter

Current fed dual active bridge converters for photovoltaic generation may typically require a given leakage or extra inductance in order to provide proper control of the currents. Therefore, the many researches have been focused on the leakage inductance control of high frequency transformer to integrate an extra inductor. In this paper, an asymmetric winding arrangement to get the controlled leakage inductance for the high frequency transformer is proposed to improve the efficiency of the current fed dual active bridge converter. In order to accurate analysis, a coupled electromagnetic analysis model of transformer connected with high frequency switching circuit is used. A design optimization procedure for high efficiency is also presented using design analysis model, and it is verified by the experimental result.

Permanent magnet structure optimization for cogging torque reduction of outer rotor type radial flux permanent magnet generator

To improve the efficiency of wind turbines, permanent magnet synchronous generator has been used instead of doubly-fed induction generator. Permanent magnet synchronous generator has higher efficiency than doubly-fed induction generator because it has no winding loss in the rotor, but it has cogging torque which increases the cut-in speed of wind turbines. Cut-in speed is a kind of major design factor of generators for the wind turbines. In previous studies, the cogging torque reduction methods are proposed but these methods have negative effects on performance or efficiency. In this paper, the rounded edge shape of permanent magnet is proposed to reduce cogging torque. The proposed method aims to design the edge of permanent magnet for minimizing the air-gap reluctance variation.

Fault Diagnosis Method of Permanent Magnet Synchronous Motor for Electrical Vehicle

The permanent magnet synchronous motor has high efficiency driving performance and high power density output characteristics compared with other motors. In addition, it has good regenerative operation characteristics during braking and deceleration driving condition. For this reason, permanent magnet synchronous motor is generally applied as a power train motor for electrical vehicle. In permanent magnet synchronous motor, the most probable causes of fault are demagnetization of rotor’s permanent magnet and short of stator winding turn. Therefore, the demagnetization fault of permanent magnet and turn fault of stator winding should be detected quickly to reduce the risk of accident and to prevent the progress of breakdown of power train system. In this paper, the fault diagnosis method using high frequency low voltage injection was suggested to diagnose the demagnetization fault of rotor permanent magnet and the turn fault of stator winding. The proposed fault diagnosis method can be used to check the faults of permanent magnet synchronous motor during system check-up process at vehicle starting and idling stop mode. The feasibility and usefulness of the proposed method were verified by the finite element analysis.

Demagnetization Diagnosis of Permanent Magnet Synchronous Motor Using Frequency Analysis at Standstill Condition

Recently, electric vehicles have got significant attention because it is more eco-friendly and efficient than internal combustion engine vehicles. Instead of an internal combustion engine, the electric vehicle has a motor for propulsion. The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and power density than other types of motor. When the irreversible demagnetization is occurred, drivers are exposed to high risk of accident by the fault operation of motor. Therefore, the irreversible demagnetization of permanent magnet should be detected to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result of locked rotor test is proposed. Based on short measurement time, the proposed diagnosis method aims to detect the demagnetization fault when an electric vehicle is at a complete standstill. The proposed method is verified through the finite element analysis.

Demagnetization diagnosis of permanent magnet synchronous motor by using continuous wavelet transform

The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and torque per weight than other types of motor. When the irreversible demagnetization is occurred, users can be exposed to high risk of accident by the fault operation of motor. Because of this, the irreversible demagnetization of permanent magnet should be detected by using any kinds of method to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result at the rated operating condition simulation is proposed for the permanent magnet synchronous motor. The input current waveforms are analyzed by using the continuous wavelet transform to detect demagnetized poles in the model.

Optimal Design of High Frequency Transformer for 150W Class Module-Integrated Converter

Recently, the module-integrated converter has shown an interest in the photovoltaic generation system. In this system, the high frequency transformer should be compact and efficient. The proposed method is based on the correlation characteristic between the copper and core loss to minimize the loss of transformer. By sizing an effective cross-sectional area and window area of core, the amount of loss is minimized. This paper presents the design and analysis of high frequency transformer by using the 3D finite element model coupled with DC-DC converter circuit for more accurate analysis by considering the nonlinear voltage and current waveforms in converter circuit. The current waveform in each winding is realized by using the ideal DC voltage source and switching component. And, the thermal analysis is performed to satisfy the electrical and thermal design criteria.

A study on design and optimization procedure of high frequency transformer for module-integrated converter

The module-integrated converter (MIC) research is interested in the small-scale photo-voltaic (PV) generation. It is capable of efficient power generation by operating at maximum power point of each PV module. In this system, the high frequency transformer should be compacted and has high efficiency characteristics to attach on the backside of PV module. However, the high frequency transformer is tallest and biggest component in converter circuit. This paper presented the core and winding structure optimization procedure to improve the efficiency of high frequency transformer in compact size. In order to obtain the accurate finite element analysis (FEA) result, the converter circuit is considered in the FEA model. The results are verified by testing the prototypes.