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Due to the high frequency nature and constant power load characteristics, stability issue exists widely in contemporary power electronic systems. Impedance-based criteria can be used in stability prediction. Thus, the accurate extraction of impedance becomes significantly important. For AC systems, impulse injection method has been proposed for its short measurement duration, but the accuracy needs...
The two opposite concepts of BE bus (battery-electric bus) which were “Short-range Frequent-charging-type” and “Night-charging-type” low-floor buses, were designed and evaluated. Firstly, the current technical level of battery and charging equipment had taken into account to conduct the vehicle design of both BE buses. In additional, the ideal performances of battery and charging equipment for fully...
The distributed generation (DG) should supply continuous power to local critical load, even in the condition of utility outage. This paper proposes a novel seamless transfer control strategy, which combines indirect current control and droop control. A microgrid structure of multi-masters and multi-slaves is also proposed, which based on the master-slave control and droop control. The master DGs are...
Traction application inverter runs in very low switching frequency to reduce switching losses, whereas in case of PMSM as traction applications, there is not a the whole speed range strategy can not only achieve synchronized SVPWM modulation but also transit to six-step mode. Based on zero-sequence voltage injection SVPWM, synchronized modulation and over-modulation methods, this paper put forward...
Interior permanent magnet synchronous motors often work under flux weakening state in electrical vehicles for higher speed but faults, such as overcurrent and overvoltage, might occur during that process, after which the power transistors are closed immediately and the battery packs are charged through three-phase uncontrolled rectifier composed of six fly-wheel diodes. It is called uncontrolled generation...
Inverters in voltage control mode including droop control and virtual synchronous generator (VSG) are promising for interconnecting the renewable energy to the grid, which are both emulating the frequency and voltage regulating functions of synchronous generators through droop method. However, improper transient impact current and reactive power output are observed for inverters in voltage control...
This paper proposes a reliability and economic evaluation model of distribution network under large scale EV's access. the Monte Carlo method was utilized to evaluate the reliability of distribution network. The cost-benefit model that considering electric vehicle charging load is set up. In order to combine the user experience with the other cost benefits like the power loss cost, sales efficiency...
This paper proposes a controller design to compensate the current harmonics from the nonlinear load when a grid-connected inverter operates as an active power filter. When the LCL filter is installed at the output of inverter, the controller should be designed differently depending on the location of the nonlinear load. As this nonlinear load is connected to the grid before or after the grid side...
With the assessment of single-phase microgrids (MGs), three-phase/single-phase (TP/SP) hybrid multi-microgrids (MMGs) are emerging, provided with more complex architecture. This paper deals with the black-start problem for TP/SP MMGs in islanded mode caused by an unscheduled breakdown from the main grid. The three-phase units, such as energy storage systems (ESSs), photovoltaic (PV) systems, and loads,...
The recently proposed concept virtual synchronous generator (VSG) has been intensively researched. Its core idea is to add a segment in traditional inverter control to simulate synchronous generator's rotor motion characteristic so that the distributed energy resources (DER) can have virtual inertia. VSG control usually contains output current amplitude limiting part to avoid too large current from...
Photovoltaic (PV) power generation has become viable alternative due to the advantages of no fuel cost and abundance of sunlight. In a grid-connected PV inverter system, besides stability and reliability, the efficiency is always an important factor. To generate active power effectively, the grid-side current must be in phase with the grid voltage. Further, the current harmonics must be low enough...
The paper proposes a low ripple high voltage converter applied in plasma field. The structure of the circuit combines conventional symmetric voltage multiplier and a parallel resonant circuit. High-output-voltage low-output-voltage-ripple converter can be achieved by the way of superposition and cancellation of capacitors' alternating signal from the parallel resonant circuit. The problem of high...
This paper proposed a hybrid power system with combined advantageous features of switching power supply and linear power amplifier. The switching power supply would provide the primary output voltage and power to the load, while the linear power amplifier would act as a correcting amplifying device to compensate for power ripple as a way to stabilize voltage output. Combination of these two components...
It's known that single-phase power factor correction (PFC) converter has second-order harmonic currents (SHC), which results in voltage ripple on DC load. The active storage unit (ASU) is employed to absorb SHC with ASU's input current (iasu) following SHC. In order to accurately extract ASU's current reference (iasu*) in a simple way, a real-time calculation method is proposed. At the same time,...
The conventional structure of buck-boost inverter uses IGBTs. IGBTs have features like long tail current, fixed voltage drop and that is why its switching losses are high. In this paper switching cells structured buck-boost inverter is proposed. In switching cell structure, MOSFETs and external diodes with very fast reverse recovery characteristics are used, while the body diodes have no chance of...
The role of electrical wheelchair has been more important in recent aging society. However, currently used electrical wheelchair is not always better solution considering human safety. For example, when the electrical wheelchair contacts a large step, it is dangerous to roll over the step with an ordinary speed. In addition, a human will be exposed to risk when a controller fails during step over...
In this paper, an LLC resonant converter using three metal-oxide-silicon field-effect transistor (MOSFET) switches is proposed for high efficiency with universal input voltage. At high line input, the proposed converter operates same as the conventional half-bridge (HB) LLC converter. At low line input, by changing the operation of three switches, the resonant tank of the proposed converter is divided...
The Hyperloop is a new transportation concept that involves high-speed transportation of passengers and cargo through a tube-enclosed system. Photovoltaic (PV) panels are located on the top of the tube to provide energy for the Hyperloop system. To develop this system, various configurations of PV panels arranged on the tube are studied and evaluated in terms of power and energy performance. This...
This paper presents present a study and implementation of a three-level boost converter. This converter feature includes low devices voltages stress requirement for high voltage application, small inductor size that leads to the reduction of cost and size and can be operated with a wide range input voltage. Unlike conventional method, output capacitor voltage balancing was done by a slight phase shift...
The use of power factor correction (PFC) converters is widely discussed and considered for most off-line power supplies. For low power applications, boost PFC converters operated in discontinuous conduction mode (DCM) or boundary conduction mode (BCM) mode are usually employed. The main advantage of BCM mode is the reduction of reversal recovery loss of diode and simple control, especially at the...
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