• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.6
• /
• pp.87-95
• /
• 2006

In this study, in order to obtain high qualify of electric power, single phase active filter which is composed of Zig-Zag transformer and three phase bridge rectifier and capacitor at the secondary of its transformer to be able to reduce the components of the zero phase current and the third harmonic current in neutral line and power line respectively. By connecting this filter to the Zig-Zag transformer and nonlinear load, their third harmonic components due to the nonlinear loads were reduced.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.326-328
• /
• 2005

In order to reduce the capital and overall operating cost of a fuel-cell system, a high-efficiency fuel-cell power inverter with a simple framework is required. The high-order two-inductance two-capacitance (LLCC) resonant technique is adopted in this study to implement a low-frequency 60-Hz sine wave voltage inverter utilized in the proton exchange membrane fuel-cell (PEMFC) system. The methodology for inverting dc voltage into low-frequency ac boltage is usually generated by the pulse-width-modulation (PWM) technique. However, the PWM-type inverter output has high-frequency harmonic components. Although an adequately designed filter could be utilized to overcome this problem, there are still some undesirable effects introduced by the high-frequency switching loss, electromagnetic-interference, harmonic current, and load variation. A novel power inverter via the LLCC resonant technique is designed for inverting dc voltage into 60-Hz ac sine wave voltage in the PEMFC system. This circuit scheme has the merits of low harmonic components, soft switching, high efficiency, and simplified implementation. The effectiveness of the proposed resonant inverter used for the PEMFC system is verified by numerical simulations and experimental results.

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1830-1843
• /
• 2018

In this paper, the generation of a reference current and voltage signal based on a Kalman filter is offered for a 3-phase 4wire UPQC (Unified Power Quality Conditioner). The performance of the UPQC is improved with source voltages that are distorted due to harmonic components. Despite harmonic and frequency variations, the Kalman filter is capable enough to determine the amplitude and the phase angle of load currents and source voltages. The calculation of the first state is sufficient to identify the fundamental components of the current, voltage and angle. Therefore, the Kalman state estimator is fast and simple. A Kalman based control strategy is proposed and implemented for a UPQC in a distribution system. The performance of the proposed control strategy is assessed for all possible source conditions with varying nonlinear and linear loads. The functioning of the proposed control algorithm with a UPQC is scrutinized and validated through simulations employing MATLAB/Simulink software. Using a FPGA SPATRAN 3A DSP board, the proposed algorithm is developed and implemented. A small-scale laboratory prototype is built to verify the simulation results. The stated control scheme for the UPQC reduces the following issues, voltage sags, voltage swells, harmonic distortions (voltage and current), unbalanced supply voltage and unbalanced power factor under dynamic and steady-state operating conditions.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.2
• /
• pp.539-544
• /
• 2015

FEA was used to analyze inductance and torque of IPMSM. Torque and inductance are analyzed on the dq-axis. It was shown that Ld and Lq have harmonic components, and magnitude as well as phase of the harmonics varies according to the current values. This paper shows the relationship between these inductance harmonics and the 6th harmonic component of torque.

• Communications of the Korean Mathematical Society
• /
• v.10 no.1
• /
• pp.145-153
• /
• 1995

A Jordan domain D in C is said to be a c-quasidisk if there exists a constant $c \geq 1$ such that each two points $z_1$ and $z_2$ in D can be joined by an arc $\tau$ in D such that $$ \ell(\tau) \leq c$\mid$z_1 - z_2$\mid$ $$ and $$ (1.1) min(\ell(\tau_1),\ell(\tau_2)) \leq c d(z, \partial D) $$ for all $z \in \tau$, where $\tau_1$ and $\tau_2$ are the components of $\tau\{z}$. Quasidisks have been extensively studied and can be characterized in many different ways [1],[2],[3].

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.409-413
• /
• 1988

In this paper a control technique for active power filters is proposed which not only eliminates the harmonic current, but also controls the reactive power at the ac side of PWM inverter-induction motor drive system. Injecting the proposed PWM current enables the harmonic components of orders not greater than the pulse number per half-cycle to be removed completely. It also enables the input power factor to become unity. Theoretical investigations are performed to evaluate the performance of the proposed control technique.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.6
• /
• pp.441-450
• /
• 1989

A control technique for current-fed filters is proposed which not only eliminates the harmonic current, but also controls the reactive power at the ac sides of PWM inverter-induction motor drive system. Injecting the proposed PWM current enables the harmonic components of orders not greater than the number of pulses per half-cycle to be removed completely. Also it enables the input fundamental power factor to become unity and hence total input power factor can be improved greatly. Digital simulation is performed to investigate the theoretical output characteristics of the current-fed filters by the proposed control technique.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.258-259
• /
• 2012

This paper proposes a new control strategy to eliminate the harmonic components of stator current for stand-alone DFIG system feeding non-linear loads. In this method, the LSC operates as an active filter which is controlled by employing a proportional-integral and a resonant controller. And also, the stator current is used as the feedback signal for the compensator instead of the load current, so that the additional current sensor at the load side can be removed. The experiment is verified to validate the effectiveness of the proposed compensating method.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.230-233
• /
• 2004

This paper is proposed that The voltage-dependant power factor model is established as 5th polynomials with convenience data type. This modeling includes the harmonic components by static experiments of individual and composite load. This paper suggested methodology for modeling bus and regional power factor with consideration of harmonics effect by load composition rates and individual load power factor models.

• Steel and Composite Structures
• /
• v.27 no.1
• /
• pp.35-48
• /
• 2018

In this paper, the response of a sandwich cylindrical shell over any sort of boundary conditions and under a general distributed static loading is investigated. The faces and the core are made of some isotropic materials. The faces are modeled as thin cylindrical shells obeying the Kirchhoff-Love assumptions. For the core material it is assumed to be thick and the in-plane stresses are negligible. The governing equations are derived using the principle of the stationary potential energy. Using harmonic differential quadrature method (HDQM) the equations are solved for deformation components. The obtained results primarily are compared against finite element results. Then, the effects of changing different parameters on the stress and displacement components of sandwich cylindrical shells are investigated.