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This paper highlights the role of power electronics and digital control in the performance improvements of RFX (Reverse Field eXperiment), a toroidal device for plasma physics studies related to nuclear fusion research. Designed and built in the `80s, it started operation in early `90s, with the mission to explore the physics of Reverse Field Pinch (RFP) configuration at high plasma current, up to...
The aim of this article is to describe how closely PV grid-connected inverters operate at the actual maximum power point. To carry this study out six 50 Hz single-phase inverters were selected from European market. Each one of them was put into an outdoor grid-connected system installed in Leganes (Madrid) Spain (by using flat and concentrating PV modules). Different electrical signals with respect...
The current characteristics of two types of parallel three-phase voltage source inverter configurations are analyzed, and the suitability of different pulse width modulation methods in the control of parallel inverters is discussed. The analysis and discussion are based on state-space models derived in this paper and presented for the parallel connection of n units. For the sake of repeatability,...
In this paper, a 600 KW electrical balance of plant (EBOP) for a molten carbonate fuel cell (MCFC) power plant is introduced. The requirements for EBOP are categorized into as follows : demands on grid interconnection and operational interface with a fuel cell. EBOP has three modes of operation, i.e. grid-connected (GC) mode, grid-independent (GI) mode, and grid-synchronization (GS) mode, to control...
Actually, AC 16.7-Hz railway grids are fed via back-to-back converters from the public grid. A flux-based multivariable control for the three-phase-side converter is presented, which takes the resonant circuit of the single-phase-side converter into account, leading to excellent stationary and dynamic behaviour.
Cable reflection phenomenon in inverter-fed electric drives and typical solutions to the problem are presented in brief. Application of a new active du/dt filtering method based on a low-loss LC circuit and active control to eliminate the motor overvoltages is discussed in this paper. Active du/dt basic principles are presented along with experimental results to verify the potential of the concept...
An LVDC (low voltage DC) distribution system is a promising technology to be used in future smart distribution system having high level cost-efficiency and reliability. Protection of an LVDC distribution system differs from the traditional 20/0.4 kV AC distribution network; direct current and IT network complicates the customer-end protection. This paper describes practical protection solutions for...
In the area of natural gas industry, there is a large interest in converters for driving high speed, medium voltage induction motors. High-speed drive systems are capable of directly driving turbo-compressors at speeds of up to 20,000 rpm / 8 MW. In high speed motor drive applications, the motor fundamental frequency can vary from 100 Hz to 300 Hz, which requires a high switching frequency. However,...
This paper presents a dual-bridge inverter approach to eliminate the motor common-mode voltage. This inverter which consists of two inverters to be connected in parallel does not generate the common-mode voltage, and can drive standard three-phase three-wire induction motors. Additionally, because one inverter does not output active power, the capacity of the inverter is very small. The effectiveness...
In this paper, a direct control of a flying capacitor inverter is proposed. This control allows to limit the number of commutations in a switching period with the use of a pre-calculated output voltage profile. A predictive control is made for the 3 phases 4 levels inverter in a active filtering operation. The advantages of this direct control is to reduce the switching frequency of the IGBTs, to...
The multi-string photovoltaic (PV) inverter is of interest for building grid-connected PV systems because it offers a number of advantages compared to conventional centralized or single-stage inverters. Optimal operation of the system can be achieved since the maximum power point (MPP) of each string is controlled by a local dc-dc converter input stage. The input dc-dc converter also provides voltage...
Dynamic performances of a wind turbine generating system consisting of series connected wind generator/rectifiers and a current source thyristor inverter are discussed. A simulation model for the whole system including the wind turbines is presented to demonstrate the feasibility of the system for the case of two wind turbine/generators. It is shown that the tip speed ratios of the individual turbines...
Influence of hydrogen fuel cell stack output current ripple caused by a one phase voltage-fed inverter system on efficiency of the fuel cell stack is investigated experimentally. The system includes hydrogen canister, 1.2 kW hydrogen fuel cell module, DC/DC step-up converter and PWM inverter. The system has two DC voltage stages: relatively low and variable voltage on the fuel cell output and stabilized...
A control algorithm is proposed for a three-phase hybrid power filter constituted by a series active filter and a shunt passive filter. The control strategy is based on the dual formulation of the vectorial theory of electrical power, so that the voltage waveform injected by the active filter is able to compensate the reactive power, to eliminate harmonics of the load current and to balance asymmetrical...
This paper reports on inverter nonlinearity effects on sensorless control methods based on high-frequency signal injection (HF-injection). Inverter output voltage distortions and their influence on position detection are described analytically and their compensation is discussed. Furthermore it is pointed out that the effects of inverter nonlinearities on sensorless control depend on whether the rotating...
This paper presents a comparison study between the operation of a back-to-back and a matrix converter induction motor drive under the presence of faults in the power switches of these converters. These two topologies are functionally equivalent in terms of input power quality and energy regeneration capabilities but need to be compared in terms of performance under faulty conditions as well due to...
In this paper a test bench will be detailed in order to verify the reliability of new inverter prototypes for future EV and HEV electric motors. Cycling tests must be carried out in order to test the reliability of new components for inverters in the same conditions as in real vehicle. A test bench using 20-30 kW induction motor or brushless DC machines has been used. These machines are coupled with...
The paper deals with the automatic generation of global model of static converters without the description of their environment. The considered models are average and exact models (i.e. with ideal switches). These models are obtained by using a software tool named AMG (for Average Model Generator) with a priori on the control mode and behaviour of the static converter. In this paper, an extension...
Linear quadratic Gaussian (LQG) based phase voltage control is implemented. The regulation performance, estimation accuracy and interference sensitivity of different LQG control schemes is evaluated and compared. Paper reveals that it is possible to make the control system more insensitive to EMI when compared to dual-loop PI control and that the synchronous co-ordinate control scheme's all-around...
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