• Journal of Power Electronics
• /
• 제9권3호
• /
• pp.438-446
• /
• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• Journal of Power Electronics
• /
• 제9권3호
• /
• pp.481-490
• /
• 2009

This paper describes a SVPWM overmodulation scheme of NPC type three-level inverter for traction drives which extends the modulation index from MI=0.907 to unity. SVPWM strategy is organized by two operation modes of under-modulation and over-modulation. The switching states under the under-modulation modes are determined by dividing them with two linear regions and one hybrid region the same as the conventional three-level inverter. On the other hand, under the over-modulation mode, they are generated by doing it with two over-modulation regions the same as the conventional over-modulation strategy of a two level inverter. Following the description of over-modulation scheme of a three-level inverter, the system description of a vector controlled induction motor for traction drives has been discussed. Finally, the validity of the proposed modulation algorithm has been verified through simulation and experimental results.

• 연구논문집
• /
• 통권27호
• /
• pp.141-151
• /
• 1997

Recently, the importance of electro-multifunction control valve which is digital control valve is increasing day after day. This is due to the demand of that the current industrial world wants the valve having simpler control circuit and higher operation reliability. It is the PWM controlled high speed electronic valve that satisfies the damands of current industrial world. But, the PWM controlled high speed electronic valve has some non-linearity characteristics like as the delay time of switching and the pressure oscillation phenomenon. These characteristics are an obstacle for the control of high speed & high efficiency in control system. Therefore, in this study, we set the studying purpose on analysis of parameter characteristics in solenoid, and on establishment of optimum design technique in high speed solenoid.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
• /
• pp.51-54
• /
• 2002

As digital systems continue to use components with faster edge rate and clock speeds, transmission of the digital information can take place many troubles. The increasing requirement for controlled impedance PCBs becomes both a critical success factor and a design challenge. Especially, the noise sources in digital system include the noise in power supply, ground and packaging due to simultaneous switching of signal, signal reflections and distortions on single and multiple transmission lines. This paper simulates the tracks controlled impedance with the test coupon. So, it can saves the design time and supports the economical PCB design.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.30-32
• /
• 1995

The SRM has high efficiency, a wide speed range, high speed capability and DC-series Motor characteristics. So the SRM has been studied as adjustable speed machine. The speed of SRM can be adjusted to switching angle and exciting voltage. This paper suggests an constant speed drive method of SRM. In this method, the speed is controlled by voltage regulation using PI control and the torque is controlled by advance angle in accordance with, load torque variation.

• 한국산학기술학회논문지
• /
• 제6권3호
• /
• pp.278-284
• /
• 2005

본 논문에서는 통신 기지국용 전원으로 사용할 수 있는 위상 제어 직렬 공진형 컨버터 시스템을 제안하고 동작 원리 및 특성을 살펴보았다. 위상 제어 직렬 공진형 컨버터 시스템은 POSR(Parallel Output Series Resonant) 형태이기 때문에 부하에 강인하고 MOSFET스위치의 위상을 제어함으로써 입력전압의 변화에도 안정된 출력을 보여준다 먼저 시스템의 분석과 PSIM프로그램을 사용한 시뮬레이션을 하였고, 또한 실제 시스템의 실험을 통하여 시스템의 특성을 확인하였다.

• 한국산학기술학회논문지
• /
• 제4권4호
• /
• pp.323-328
• /
• 2003

본 논문에서는 통신 기지국용 전원으로 사용할 수 있는 직렬 공진형 컨버터 시스템의 새로운 제어방식을 제안하였다. 주파수 제어 직렬 공진형 컨버터 시스템은 병렬 출력 직렬 공진(Parallel Output Series Resonant: POSR)형태이기 때문에 부하변동에 강인하다. 또한 스위칭 주파수를 제어함으로써 입력전압의 변화에도 안정된 출력을 제공한다. 실제 시스템 제작에 앞서 제안된 병렬 출력 직렬 공진형 컨버터 시스템의 분석을 하였고 ACSL(Advanced Continuous Simulation Language)을 이용한 모의실험을 하였다. 또한 실제의 시스템을 제작 및 실험을 통하여 시스템 특성을 확인하였다.

• Journal of Electrical Engineering and Technology
• /
• 제8권2호
• /
• pp.230-237
• /
• 2013

This paper presents a novel nonlinear model of Switched Reluctance Generator (SRG) based on wind Energy Conversion system. Closed loop control with based Proportional Integrator current Chopping Control machine model is used. A Power converter in SRG can be controlled by using PI-CCC proposed model, and can be produced maximum power efficiency and minimize the ripple contents in the output of SRG. A second power converter namely PI based controlled PWM Inverter is used to interface the machine to the Grid. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltage needs less power switching devices and each pair of turbine the generated active power starts increasing smoothly. This proposed control scheme feasibility and validity are simulated on SIMULINK/SIM POWER SYSTEMS only.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2005년도 전력전자학술대회 논문집
• /
• pp.106-108
• /
• 2005

High accuracy and stability digital controlled power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ${\sim}$ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 A step resolution at full range and the stability of +/- 1.5 ppm for short term and +/- 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 A
• /
• pp.111-114
• /
• 1999

This paper deals with the rated output power using grid-connected Doubly-Fed Induction Generator(DFIG) in the supersynchronous speed regions. The rated output power is controlled by both magnitude and frequency of the voltage fed to the rotor. And this rotor voltage is controlled by control of inverter switching frequency and fire angle. A DFIG generating characteristic is analyzed by simulation of steady-state algebraic equation of equivalent circuit using numerical analysis. And it is compared with results of experiment. Consequently, This paper presented to control method for rated output power of DFIG in variable wind speed.