Hye-Ung Shin

Improved torque ripple reduction method of five-phase induction motor using fuzzy controller

This paper presents a new torque ripple reduction method using the direct torque control (DTC) of five-phase induction motor. The main advantages of DTC are a fast response and a simple control. However, these advantages come with a cost of increased torque ripples. Therefore, it is essential to use the torque ripple reduction method in DTC. The main idea of this proposed algorithm for reduction of the torque ripple is to calculate a constant value using the fuzzy controller. The constant value is used to calculate the non-zero vector inserting time in sampling time. The torque error value is used as input to the fuzzy controller. Therefore, the constant value which is obtained by the output of the fuzzy controller is the optimal value for the torque ripple reduction. The effectiveness of the proposed torque ripple reduction method is verified by the simulation results.

Optimal design of a switched reluctance generator for small wind power system using a genetic algorithm

This paper deals with the optimal design of a 1 kW-switched reluctance generator (SRG) for wind power applications. The optimal design of the SRG uses the design variables based on the basic design model. Latin hypercube sampling (LHS) is used to extract the samples of design variables. Kriging Method is used to approximate the objective and constraints functions, while genetic algorithm (GA) is used to optimize the generator design. The efficiency and the power density of the basic design model and the optimal model are compared.

Design of a Troidal Type Gyro using Repulsive Power of Permanent Magnet and Coriolis Effect

This paper deals with the design of 1-kW troidal type gyro. In general, gyro can be used as magnet bearing or flywheel energy storage device. The proposed troidal type gyro is used as a flywheel energy storage device. The gyro is capable of high-speed rotation in the air. The coriolis effect is taken into account when designing the rotor of the proposed gyro. Also the repulsive power of the permanent magnet is considered while selecting the shape and the thickness of the magnet. The neodymium is used as material of the magnets in this paper. The number of magnets are selected accordingly to reduce these torque ripples because torque ripples is an important factor while designing the gyro. The designed troidal type gyro is verified through the Finite Element Method (FEM).

Basic Control of AC Motor Drives

Abstract The basic principle and control of AC motor drives are introduced in this chapter. AC motors are divided into induction motors and permanent magnet synchronous motors. The principle of each type of AC motor is introduced. In addition, the vector control of AC motor drives is introduced as a basic control. Simulation is performed in an AC motor drive system to verify the basic control of the AC motor drive.

DC-Link Capacitor-Current Ripple Reduction in DPWM-Based Back-to-Back Converters

This paper proposes an improved offset selection method for discontinuous-pulse-width-modulation (DPWM)-based back-to-back converters to reduce dc-link current ripple. DPWM is introduced to power converters to diminish the stress on power transistors and prolong their lifespan. However, when using the DPWM method, the dc-link current ripple is increased in nonswitching regions of the power transistors. Moreover, in DPWM-based back-to-back converters, the dc-link current ripple reaches its maximum when the two transistors of both inverters are clamped in opposite directions. Therefore, the dc-link capacitors endure more stress, resulting in decreased life duration. To overcome this issue, the switching method should consider the clamping periods, when the current ripple increases. This can be achieved by modifying the DPWM offset, so that the clamping states of both converters are matched. The effectiveness of the proposed method is confirmed by both simulation and experimental results.

Fault diagnosis method for power transistors in switched reluctance machine drive system

This paper proposes a new fault diagnosis method for a switched reluctance machine (SRM) drive system. The proposed fault diagnosis method is capable of detecting both open circuit and short circuit faults in the power converter switches. In addition, the position of a short fault in the asymmetric bridge converter can be detected using another proposed method. This fault occurrence can be identified in the affected motor phase. A simulation is performed with a SRM drive system, and the results are presented to verify the validity of the proposed method.

Open Fault Diagnosis Method for Five-Phase Induction Motor Driving System

This paper proposes a fault diagnosis method for an open-fault in inverter driving five-phase induction motor. The five-phase induction motor has a high output torque and small torque ripple in comparison to three-phase. The best advantage of the five-phase induction motor is fault diagnosis and tolerant control using redundancy of phases. This paper uses an inverter as a power converter for driving a five-phase induction motor. If a switch of inverter occurs to the open-fault, this problem is the influence on the output current and output torque. To solve this problem, there is need of an accurate diagnosis and fault switch distinction. Therefore, this paper propose a fault detection method of the open-fault switches for the fault diagnosis. First, analyzing the pattern for the open-circuit fault of one phase. next, analyzing the pattern for the open-circuit fault of each inverter switches. Through the pattern analysis, It defines the scope of each of the failure switch. Thereafter, By using an algorithm that proposes to perform a fault diagnosis method. The proposed algorithm is verified from the experiment with the 1.5 kW five-phase induction motor.

Fault-tolerant switched reluctance machine drives using a current Park's vector

This paper presents a new fault-tolerant technique, on the basis of the current Parks vector, which is applied to switched reluctance machine (SRM) drives. Open- and short-fault occur in the power converter switches. A proposed current Parks vector can diagnose these faults. In addition, A position of the short-fault in the asymmetric bridge converter can be detected using the proposed another method. The fault-tolerant controls are performed after a fault diagnosis. An open-fault tolerant control can perform considering the adjacent phase switches. A short-fault tolerant control can perform using remaining switch of fault phase. These fault occurrences can be identified in the affected motor phase. A simulation is performed with a four-phase SRM drive system, and the results are presented to verify the validity of the proposed method.

Torque Ripple Minimization for Switched Reluctance Motors Using a Fuzzy Logic and Sliding Mode Control

This paper presents a torque ripple reduction algorithm for the switched reluctance motor drives using the fuzzy logic and the sliding mode control. A turn-on angle controller based on the fuzzy logic determines the optimal turn-on angle. In addition, a sliding mode torque control (SMTC) methods reduces torque ripples instantaneously in the commutation region. The proposed algorithm does not require complex system models considering nonlinear magnetizing or demagnetizing periods of the phase current. According to the rotor speed and torque, the proposed controller changes the turn-on angle and reference torque instantaneously until the torque ripples are minimized. The simulation and experimental results verify the validity of minimizing the torque ripple performance.