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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...
A coupled system simulator, based on analytical circuit equations and a finite element method (FEM) model of the motor, is used to analyze a direct-torque-controlled (DTC) frequency-converter-fed industrial 200 kW squirrel-cage induction motor. The measured stator voltage waveforms are used as inputs to the FEM motor model, and the results are compared with the measured ones. Comparison is also made...
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,...
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...
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...
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...
It has been reported that the fundamental space vector PWM (SVPWM) waveforms of both a DC link voltage source inverter (VSI) and a matrix converter (MC) can be used as excitation signals for position estimation of a permanent magnet synchronous motor (PMSM). This paper evaluates the quality of the position estimates as well as the influence when the sensorless algorithm is implemented on a VSI and...
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...
Hybrid buses are currently enjoying a very high level of interest worldwide. For this market an inverter family was developed using the latest IGBT technology. The tough operating conditions, and especially the mission profile in hybrid drives, represent a big challenge for IGBT modules. Electrical, thermal and lifetime limitations reduce the level to which they can be exploited. New IGBT developments...
This paper presents a review of some techniques for islanding detection, especially by using inverter based DG applications and it also focuses on several islanding detection methods for a single-phase current-control voltage inverter working with a PV system connected into the grid. It is deliberated a single-phase inverter with maximum power of 5 kW. Islanding detection methods are investigated,...
The drive system of a variable speed pump-storage power station consisting of a doubly-fed induction machine with a 3-level voltage source inverter feeding the rotor is presented. The advantages of variable speed pump-storage power stations are outlined. After a short comparison with the classical cyclo-converter solution the voltage source inverter solution is described in detail covering various...
In the design of induction motor adjustable-speed drives, the same efficiency and performance requirements can be achieved with different choices as far as the motor and the inverter individual size is concerned. Depending on the specific functions that relate motor and inverter size to their respective cost, each choice is expected to result in a different overall drive cost. This paper presents...
This paper deals with the control of a medium voltage 3 level inverter supplying a high speed induction machine via a Sinus filter. The sinus filter dynamic impacts the global model, and induce a resonance frequency, that has to be managed to ensure the global stability. Two control methods are presented with site experimental results of 6 MW 10000 rpm application.
Distributed power generation is expected to deliver power into the grid without interruption during voltage dips. To improve system ride-through capabilities, a generalized active power control strategy is proposed for grid-interfacing inverters. Specifically, a current reference generation strategy based on symmetric-sequence components of unbalanced three-phase three-wire or four-wire systems is...
This document describes the implementation of the model predictive direct torque control (MPDTC) algorithm for the control of three-phase induction motor drives comprising a three-level dc-link inverter with an output LC filter. As the filter introduces delays in the system, the motor torque and flux are no longer directly controllable. Therefore the inverter torque and flux are introduced and the...
This paper investigates the problem of single-phase induction motor (SPIM) sensorless speed control. A discrete time PI controller and a sensorless technique are implemented on a PC-based platform using a standard three-phase inverter drive and vector control. An indirect rotor flux oriented control technique is developed based on a sensorless technique. A MRAS with a Kalman filter algorithm is developed...
Predictive control is becoming an alternative to standard vector control or direct torque control in electrical drives due to its fast torque response and design flexibility. In multiphase drives, where the complexity of the modulation techniques and control schemes is higher, the predictive control has proved to be a promising alternative. The main shortcoming of the standard predictive control (SPC)...
Microgrids (MGs) are one of the most promising electrical systems for the next years. Since the definition of the MG paradigm by the first time, the investigation in this area is growing continuously and there are numerous research projects in this moment over the world. This paper makes a survey focused on two important features of MGs: unplanned islanding detection algorithms and inverter control...
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