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Almost all existing relevant literatures are focused on the multi-inverter system that only contains one type of inverter. Till now, the interactions in multi-inverter system consisting of polytype inverters have been not investigated systematically. To fill this gap, the paper is aimed at the stability study of the generic system containing multiple types of inverters. The mathematic model of interactions...
In cascaded-type microgrid, the synchronization and power sharing of distributed generators (DGs) become two new issues that needs to be addressed urgently. In this paper, a unified droop control is proposed and its stability is analyzed in the islanded mode. The proposed scheme can ensure the system stability and accurate power sharing without communication in four-quadrant operations. Finally, simulation...
In order to improve the efficiency, we should know the loss characteristics of inverter-fed induction motors. We first have to accurately measure the total motor losses, and then obtain each loss component by reasonably separate the total motor losses. In this paper, the total losses of a 5.5 kW, a 22 kW, a 30 kW, a 37 kW, a 45 kW and a 55 kW induction motors under sinusoidal supply and PWM inverter...
Permanent magnet synchronous motor (PMSM) drives include several design and control variables that affect power losses. The improvement in system efficiency through control techniques will reduce the size of inverter and motor cooling system as well as the operating costs of the system. This paper proposes a comprehensive analysis of loss controllability using various control parameters to reduce...
Multiport Converter gets growing applications due to its advantages of flexible control mode, high power density, bidirectional power delivery capability etc. In this paper, a DAB based partial isolated DC-AC multiport power converter, which combines photovoltaic panel, battery storage and grid connection is studied. Modulation method, analysis for power transmission and control design are provided...
Impedance source inverters have attracted much attention in recent years due to their ability to behave as voltage elevators/reducers at their output terminals without the need of an extra dc/dc converter to accomplish this task. Among these inverters, the quasi-impedance source inverter (qZSI) is one of the most known topologies. It considers two basic operating states, the no-shoot-through state...
Anew control strategy to achieve high performance from solar photovoltaic system using single stage inverter interfacing grid without maximum power point tracking (MPPT) techniques is investigated in this paper. Sinusoid-tracking algorithm and adaptive filter is proposed to improve the power quality and to regulate constant AC voltage at the point of common coupling (PCC). Proportional integral controllers...
A novel discrete sinusoidal signal integrator (DSSI) structure is proposed in this paper for single grid-tied inverters. The DSSI provides an adjustable gain and bandwidth at the expected frequency and a highly attenuated gain at other frequencies which make the DSSI based controllers obtain the zero steady-state error tracking performance of arbitrary frequencies. The performance of the conventional...
In an islanded microgrid, harmonic current is controlled (or shared) by modifying the effective impedance in the path of harmonic current. This effective impedance includes line impedance and the internal impedance of the generation unit. Reported works consider the aforementioned impedances as separate entities and their combined effect in harmonic current flow has not been discussed so far. This...
Eco mode UPS will power the load with mains power supply directly when the quality of mains power supply is good. When the quality of mains power supply decreases Eco mode UPS will switch to double conversion mode rapidly to meet the requirement of power quality. Eco mode UPS has the highest efficiency and the highest reliability. Using Eco mode UPS is an important measure of data center energy saving,...
A modular UPS system is generally presented as having a much higher level of availability than a monolithic, double conversion, on-line UPS system. However, there are different types of modular UPS systems available on the market, with varying degrees of reliability and availability. To represent the strengths and weaknesses of each architecture and accurately compare them to one another, a detailed...
Current source inverter (CSI) is a family of power converters which has been recently investigated for photovoltaic power conversion in grid-tied operation, due to the inherent boost capability and ease of control. This paper assess Photovoltaic three-phase Current Source Inverters by two different CSI topologies and space vector modulation commutation strategies. Different CSI solutions are therefore...
This paper presents a cascaded, highly efficient and reliable inverter configuration (HERIC) based multi-level inverter (MLI) to minimise the leakage current in the PV applications. The cascaded HERIC based nine-level MLI proposed in this paper requires less number of power semiconductor devices when compared with the conventional neutral point clamped (NPC), flying capacitor and cascaded H-bridge...
In this paper, the single-stage Maximum Power Point Tracking (MPPT) control strategy for the Aalborg photovoltaic inverter is presented. Aalborg inverter has many advantages, such as high efficiency, wide range of input voltage, minimum voltage drop of the filtering inductors, etc. Nevertheless, it is essentially a “half-bridge” inverter with two input sources, where one source works in MPPT mode,...
Transformerless inverters are being widely used in low power grid-connected photovoltaic (PV) generation systems. Transformer elimination has many advantages; it reduces cost, size, weight and also increases the whole system efficiency. However, once the transformer is removed, there is no galvanic isolation between grid and PV array and, as a consequence, a leakage current may appears due to the...
In DC-biased sinusoidal current vernier reluctance machines (DC-biased-VRMs), the DC exciting winding and AC armature winding are integrated into one single winding. Therefore, the copper loss can be reduced with torque density increasing, and only one set of power electronic converter is demanded. This paper is to propose a DC-biased-VRMs drive with asymmetrical power electronics devices and corresponding...
In this paper, a dual parallel connected brushless direct current (BLDC) motors drive system fed by a single inverter is presented and the control method for stable operation in electric vehicles (EVs) application is proposed. To obtain the stability of such a system, both motors should always be respect the synchronism even if they have different load torque. The proposed control method is based...
The linear vernier permanent-magnet (LVPM) motor incorporates the merits of high efficiency and low cost, which is very suitable for long stroke applications. This paper proposed a new direct thrust force control for dual inverter fed open-end winding LVPM motor to reduce force ripple. First, the topology and structural characteristics of the LVPM motor are briefly presented. Second, the mathematic...
Due to the current constraint of linear induction machine (LIM) and voltage constraint of inverter, the output thrust of LIM is limited. So, in order to make LIM output thrust as large as possible within current and voltage limit, firstly, the maximum thrust per ampere (MTPA) is used to achieve maximum thrust with limited current in low speed. Secondly, with the speed of LIM increasing, the voltage...
This paper proposes a non-symmetrical permanent-magnet linear motor traction system (PMLMTS), in which the primary permanent-magnet linear motor (PMLM) is employed. Four movers are mounted with same phase angles. There are nine legs, including eight independent legs and one common leg. All legs have same normal voltage but different normal currents. The normal current of the common leg is four times...
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