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We have proposed a novel transformer model using magnetic circuit. Numerical simulations using PSCAD/EMTDC has been performed, and the performance have been examined.
This paper proposes the simple and seamless operation technique for bi-directional LLC resonant converter. Generally, bi-directional operation of LLC resonant converter is complicated and difficult to control. Because, the switching frequency has to be changed across fsr (series resonant frequency) and the switching sequences (the switching timing between high voltage side and low voltage side) has...
The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal models, only the electrical loadings are focused and treated as design variables, while the device rating is normally pre-defined by experience with poor design flexibility. Consequently a more complete loss and thermal model...
This paper introduces concept of discrete control method of class E amplifier which keeps nominal operation for varying load resistance. In the proposed method, shunt capacitance and output resonant capacitance are varied electronically by setting status of switches which are connected to capacitances. Proposed method can keep nominal operation, i.e., ZVS and ZDS, both when load resistance is higher...
Spread spectrum time domain reflectometry (SSTDR) has been applied to a live PV inverter circuit to measure impedance variations caused by natural degradation in switching devices (MOSFET), and this method was applied without altering the normal operation of the circuit. Therefore, the proposed technique is able to perform condition monitoring - the state of health of the inverter. The experimental...
The harmonic currents generated by the line-side converter of high speed trains may cause the time-varying resonances when the harmonic frequency is close to the resonance frequency of the power supply line. It may destroy the facilities in the power supply range and affect the operation of trains. To avoid the affection, the characteristic of resonance impedance is calculated and simulated with a...
In recent years, renewable energy system such as Photovoltaic generation system (PV) is widely introduced in distribution system. On the other hand, voltage deviation due to voltage fluctuation and unbalanced voltage caused by PV becomes serious problem. In order to mitigate those problems, the Combined type Dynamic Voltage Regulator (C-DVR) which consists of a step voltage regulator and AC chopper...
This paper presents an impedance-based analysis of active frequency drift (AFD) islanding detection method for grid-tied inverter systems. To study the AFD islanding detection method, output impedance of grid-tied inverter is modeled. Islanding detection is analyzed using the interaction between inverter output impedance and load impedance. The analysis further shows that the AFD islanding detection...
In islanding microgrid, the impact of line impedance on the proportional power sharing cannot be neglected if multi-inverters are operated to form a microgrid. In this paper, an improved droop controller is proposed to reduce the unexpected dynamic and steady power sharing errors caused by the mismatching of line impedance. With this proposed combined compensation, the power quality, the dynamic and...
The disturbance voltage of air conditioners may be degraded, depending on the combination of the outdoor and indoor units. This paper describes a technique to simulate the disturbance voltage of an air conditioner and examines the propagation path of conductive noise when two or more indoor units are connected to the outdoor unit.
This paper proposes an integrated common and differential mode filter with passive damping for single-phase grid-connected transformerless photovoltaic (PV) microinverters, employing the full-bridge voltage source inverter (VSI) topology with continuous unipolar modulation. This strategy achieves low current distortion, low leakage current and high efficiency. A design procedure for the proposed filter...
When the stability issues of multi-module distributed DC power system are analyzed, the physical understandings of terminal characteristics of each module should be focused. According to the proposed analysis method, all the sub-modules are divided into two groups based on the different terminal property types: impedance (Z) type and admittance (Y) type. Equivalent circuits of total system are established...
This paper summarizes the research progress in the field of Wireless Power Transmission (WPT) using Magnetic Resonance Coupling. To make the technique of WPT feasible for industrial and commercial applications it is vital to achieve a stable operation of power transmission from the source to the load under different conditions such as load and distance variations and antennas misalignment. To achieve...
For the problem that paralleled inverters cannot share reactive power proportional to their power capacity in islanding microgrid. Originally, the effect of inverter output impedance and line impedance to reactive power sharing with conventional droop control is analyzed. Following, a method adjusting the output reactive power by paralleling capacitor at the inverter output is proposed, and the relationship...
Impedance is an important parameter to analysis the stability of microgrid. Stability criteria have been developed in terms of source and load impedances for both dc and ac systems, and it is often helpful to have techniques for impedance measurement. First, the theoretical impedance of microgrid is calculated in this paper. Second, a new method of impedance measurement for microgrid is introduced...
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