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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...
The predictive direct power control (P-DPC) strategy computes the application times of several voltage-vectors included in a predefined sequence. Until now only approximate solutions of the P-DPC have been presented. This contribution proposes two improvements to the P-DPC: the exact solution of the control problem and the fastest possible transient.
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...
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 article presents the study and implementation of a new asymmetric hybrid voltage inverter, for high voltage applications. The proposed inverter employs two types of modulation in low and high frequency (sinusoidal PWM). Simulations and experiment results are provided showing the validity of the analyses. These were obtained using a low-voltage single-phase prototype that demonstrated its operation.
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...
This paper presents a laboratory setup for teaching basics of power electronics. The setup consists of a 3 phase transformer, a rectifier and four half-bridges. The latter can be configured as DC-DC converters (buck and full-bridge converter) or as AC-DC converters (one and three phase voltage-source inverters). Different PWM control schemes as well as on-off current control are implemented. It allows...
Investigation of conducted electromagnetic interference (EMI) in AC motor drives fed by a pulse width modulated (PWM) voltage converters requires that converters', motor windings' and feeding cables' parasitic capacitances have to be taken into account. Motor voltage transients and related EMI emission are substantially correlated with resonance effects occurring in load circuits. Frequency impedance...
This paper investigates the interactions which arise between grid connected photovoltaic inverter systems and the electrical grid. In particular, it considers the effect of grid voltage harmonics and grid impedance on the current control performance of grid connected inverter systems. In these photovoltaic inverter systems it is usual to control unity power factor, sinusoidal, current into the grid...
Undesired low-frequency self-sustained speed oscillations are encountered in fan, compressor and pump drives utilizing open-loop frequency-controlled induction motor drives. Discontinuous rectifier current at light loads and the dead-time of the inverter switches are the main sources of such oscillations. This paper proposes a concise analytical method to predict the risk of self-sustained oscillations...
In the paper a new three-level converter is presented. The proposed topology was named 3L-ASNPC (Active-Stacked-NPC) and its main advantage is the reducing of the average switching frequency for all power devices. In the same time, the apparent switching frequency of the output voltage is naturally doubled. Experimental results are shown in the paper in order to validate the proposed topology and...
A new switching scheme for ZVS of inductive decoupled high voltage IGBTs is proposed. Each half bridge, consisting of two IGBT and two diodes, is split into two parallel half-bridges. The outputs of these half-bridges are decoupled by an inductance. An alternating switching scheme leads to hard switching turn-off and zero voltage switching turn-on. The IGBT turn-on losses can be reduced to less than...
The three-level neutral point clamped converter is one of the most important multilevel converters. Two important features of the neutral point clamped converter are the neutral point balance and the output voltage characteristics. Carrier and space vector Pulse-Width Modulation control methods efficiently manage the two issues. This paper analyses the voltage balancing problem and shows that a simple...
The cross connected intermediate level (CCIL) voltage source inverter topology was first introduced in the work of Chaudhuri et. al (2007). The idea behind this novel multilevel topology is to explore the area of reduced number of component topologies producing large number of voltage levels. Mathematical modeling of the electrical circuit for the understanding and the control of the capacitor voltage...
Pumps are widely used in industrial applications, and they account for nearly a quarter of the electric energy consumption in the European industry. Pumps are often overdimensioned or they may be driven inefficiently, which causes unnecessary energy costs. If the pump drive is not equipped with appropriate measurements, inefficient pump operation may remain undetected for years and lead to a premature...
A multilevel multistage inverter design and its corresponding control strategy are presented. The hybrid inverter has a high voltage stage composed of the six-switch conventional three phase inverter with its outputs connected in series to the outputs of three-level H-bridge medium and low voltage stages. The voltage ratio has been selected to form 18-level provide maximum number of uniform steps...
This paper presents a new hybrid current control scheme for dead-time compensations and power density optimization of grid-connected dc/ac inverter. A sliding mode controller is designed for compensating the dead-time nonlinear operations, and a PI controller operates in the linear areas. According to the SMC controller output, the unnecessary gate drive signals are removed and the counter side switch...
This paper presents an alternating magnetic-field generator at 20 kHz for biological research using a single phase inverter and a series LC resonant circuit. Both single coil and multiple coil magnetic-field generators are designed and their effectiveness is confirmed by analytical and experimental results. These results demonstrate that the magnetic-field generator can produce 8 mT at a frequency...
This paper presents a model predictive current control strategy for a multilevel cascaded inverter. A simple discrete model is used to predict the behavior of the system for each possible voltage vector generated by the inverter. The voltage vector that minimizes a cost function is selected and applied during a whole sampling interval. The cost function measures the load current error. Due to the...
In this paper a precise and simple methodology will be introduced for modeling and calculating the voltage source inverter (VSI) losses in hybrid electric vehicles (HEV) application. The noteworthy traction inverter losses, consisting switching and conduction losses of diodes and IGBTs, are important for evaluating the overall efficiency and obtaining the optimized value of its dc-link voltage as...
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