• Journal of Electrical Engineering and Technology
• /
• v.5 no.4
• /
• pp.614-622
• /
• 2010

This paper presents a control method, which reduces the pulsating torque and DC voltage problems of a doubly fed induction generator (DFIG)-based wind turbine system. To reduce the torque and power ripple, a current control scheme consisting of a proportional integral (PI) controller is presented in a positive synchronously rotating reference frame, which is capable of providing precise current control for a rotor-side converter with separated positive and negative components. The power theory can reduce the oscillation of the DC-link voltage in the grid-side converter. In this paper, the generator model is examined, and simulation results are obtained with a 3 kW DFIG-based wind turbine system to verify the proposed control strategy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.6
• /
• pp.42-48
• /
• 2011

Generally, the structure without the stator core Axial Field Permanent Magnet (AFPM) generator was simple and there was nearly no cogging toque. And because it had the wide driving rate area, it had been being mainly used in the small wind power generation system. However, AFPM generator with non-slotted stator can't generate high voltage at low wind speed due to long air-gap. It is the reason of output efficiency drop. Therefore, in this paper, the AFPM synchronous generator with internal rotor and dual slotted stators for the small wind turbine is studied, and deal with a cogging torque minimization through the determination of optimum pole-arc ratio.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.11
• /
• pp.755-760
• /
• 2016

The demand for independent generators using renewable energy has been increasing. Among those independent generators, small wind turbine generators have been actively developed. Permanent magnets are generally used for small wind turbine generators to realize a simple structure and small volume. On the other hand, cogging torque is included due to the structure of the permanent magnet synchronous machine, which can be the source of noise and vibration. The cogging torque can be varied by the shape of the permanent magnet and core, and it can be reduced using the appropriate design techniques. This paper proposes a design technique that can reduce the cogging torque by changing the shape of the permanent magnets for SPMSM (Surface Permanent Magnet Synchronous Motor), which is used widely for small wind turbine generators. Evolution Strategy, which is one of non-deterministic optimization techniques, was adopted to find the optimal shape of the permanent magnets that can reduce the cogging torque. The angle and outer diameter of permanent magnet were set as the design variable. A 300W class wind turbine generator, whose pole/slot combination was 8 poles/18 slots, was designed with the proposed design technique. The properties of the generator, including the cogging torque and output voltage, were calculated. The calculation results showed that the cogging torque of the optimized model was reduced compared to that of the initial model. The design technique proposed by this paper can be an effective measure to reduce the cogging torque.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.10
• /
• pp.1147-1154
• /
• 2012

In this study, a method for designing blade pitch and generator torque controllers for a wind turbine generator is presented. This method consists of two steps. First, the Lyapunov stability theory is used to obtain nonlinear control laws that can regulate the rotor speed and the power output at all operating ranges. The blade pitch controller is chosen such that it always decreases a positive definite function that represents the error in rotor speed control. Similarly, the generator torque controller always decreases a positive definite function that reflects the error in power output control. Then, the simulation-based optimization technique is used to tune the design parameters. The controller design procedure and simulation results are presented using the widely adopted two-mass model of the wind turbine.

• Journal of Magnetics
• /
• v.22 no.2
• /
• pp.257-265
• /
• 2017

This paper presents a 2-D analytical method to calculate the back EMF of the axial flux permanent magnet synchronous generator (AFPMSG) with coreless stator and dual rotor having magnets mounted on both sides of rotor yoke. Furthermore, in order to reduce the no load voltage total harmonics distortion (VTHD), the initial model of the coreless AFPMSG is optimized by using a developed analytical method. Optimization using the 2-D analytical method reduces the optimization time to less than a minute. The back EMF obtained by using the 2-D analytical method is verified by a time stepped 3-D finite element analysis (FEA) for both the initial and optimized model. Finally, the VTHD, output torque and torque ripples of both the initial and optimized models are compared with 3D-FEA. The result shows that the optimized model reduces the VTHD and torque ripples as compared to the initial model. Furthermore, the result also shows that output torque increases as the result of the optimization.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.5
• /
• pp.503-510
• /
• 2011

This paper presents a method of optimizing the blade pitch and generator torque controllers which have been already designed for an existing wind turbine generator system. Since the highly nonlinear and uncertain characteristics of the wind turbine generator can not be fully considered in the controller design phase, some parameters such as control gains must be tuned during the field implementation phase. In this paper, nonlinear simulation software, which is based high fidelity wind turbine model, and optimization technique are effectively combined and used to tune a set of gains for the blade pitch and the generator torque controllers. Simulation results show that the baseline controllers can be effectively optimized to reduce the errors in wind turbine rotor speed and generator power output controls as well as twisting of the high and low speed shafts.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.8
• /
• pp.467-474
• /
• 2002

In this paper, a wind power simulator is designed and implemented. To realize the torque of wind blade, a DC motor is used as a variable torque input device. An induction machine is used as a generator of which speed is controlled to maintain the optimal tip speed ratio during wind speed change. Input torque of system is controlled by armature current of DC motor and speed is controlled by generator control unit using field oriented control algorithm. Various control algorithms such as MPPT, soft start up, the simulator reactive power control, can be developed and tested using the simulator.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.4
• /
• pp.930-937
• /
• 2013

In this paper, a motor control algorithm for performing a mode change without an integrated starter generator (ISG) is suggested for the automatic transmission-based hybrid electric vehicle (HEV). Dynamic models of the HEV powertrains such as engine, motor, and mode clutch are derived for the transient state during the mode change, and the HEV performance simulator is developed. Using the HEV performance bench tester, the characteristics of the mode clutch torque are measured and the motor torque required for the mode clutch synchronization is determined. Based on the dynamic models and the mode clutch torque, a motor torque control algorithm is presented for mode changes, and motor control without the ISG is investigated and compared with the existing ISG control.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.1298-1303
• /
• 2015

Diesel engine generators are widely used in the world, especially in remote site power systems as distributed generators. A weak distribution feeder with a small diesel engine may suffer from voltage and power fluctuations due to misfiring of the engine cylinder. In this study, new generator model with example engine torque was developed for the electromagnetic transient analysis program for power systems named XTAP. The configuration and verification results of the developed model are presented in the paper. The model is considered to be useful for analyses of small power systems with those diesel engines.

• Progress in Superconductivity and Cryogenics
• /
• v.2 no.2
• /
• pp.26-31
• /
• 2000

This paper deals with finite element analysis of 2GVA superconducting generator which has slitted electrothermal shield in d-axis (SES). Three phase fault is considered torque of the S.C.G. Using the result, generator parameters are calculated by F.E.M. The results are compared with superconducting generator having conventional electrothermal shield (CES). The result shows that quick response excitation could be applied to superconducting generator with slitted electrothermal shield.