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In this paper, a sensorless induction motor (IM) drive using speed observer system is presented. The system includes load torque computation for gear fault detection. Nonlinear control method is adopted for controlling the motor over a wide speed range. An LC filter for smoothing current and voltage waveforms is used at the output of the voltage inverter. The use of filter imposes more building of...
The voltage source inverter (VSI) of an uninterruptible power supply (UPS) is a system where the main objective is to obtain a high quality output sinusoidal voltage with independence on the output load. For this reason, it includes an output LC filter. The presence of the filter increases the complexity of the controller design thus it is necessary to evaluate the performance of the control strategy...
This paper presents a control algorithm based on feedback linearization technique for grid-connected three-phase non-dispatchable distributed generation (DG) systems such as a wind or a solar based generator. The power electronic interface is a voltage source inverter (VSI) and the output low-pass filter is an inductance (L) or an inductance-capacitance-inductance (LCL) circuit. The control objectives...
In this paper, authors propose a novel six-band hysteresis technique to control the seven level packed U cells (PUC) converter which was first introduced in. This converter combines advantages of the flying capacitor and the cascaded H-bridge topologies. The study of the novel converter allows the establishment of the switches gates signals equations. In case of rectifier operation, the proposed six-band...
Power electronic converters are commonly used for interfacing distributed generation systems to the electrical power network. This paper deals with a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation. The idea is to integrate the DG unit functions with shunt active power filter capabilities...
In this paper an UPQC (Unified Power Quality Conditioner) with a FLFB (Four-Leg Full-Bridge) inverter used as a Shunt Active Filter is presented. The UPQC works in a three-phase four-wire electrical system in order to compensate for nonlinear and asymmetrical loads, and disturbances in the power supply voltage. For the generation of reference currents for the FLFB the instantaneous power theory in...
A novel proposal of multilevel inverter is presented in this paper. The concept of the proposed topology is based on the association of Buck EIE converters in order to constitute a multilevel inverter and to provide an ac output voltage with low harmonic distortion and low voltage stress over the power semiconductor devices. The output voltage provided by the proposed multilevel is totally controlled...
A three-phase stand-alone PV generation system with unbalanced loads is designed in this paper. The main circuit topology of half-bridge inverter is adopted. Through a LC filter and transformer, local loads are supplied. After analyzing the produce reason of unbalanced voltage, a simple control strategy based voltage single loop is proposed, which makes the three-phase stand-alone PV generation system...
This paper presents a half-bridge-type inverter with hysteresis current control and unipolar modulation. The unipolar modulation strategy is adopted, thus the volume and weight of the output filter can be reduced compared with the conventional half-bridge inverter. In addition, as the voltage change during the switching process is just half of the input voltage, the switching losses can be reduced...
This paper presents an output current control method for grid-connected voltage-source inverter (VSI) with LCL output filter. LCL filter has been shown to provide a high attenuation to high-frequency harmonics with small physical size than other types of filters, like L and LC filters. However, filter oscillation is the major concern in this type of filter. Different passive and active damping methods...
This paper deals with a design method of LCL filter for grid-connected three-phase PWM voltage source inverters (VSI). By analyzing the total harmonic distortion of the current (THDi) in the inverter-side inductor and the ripple attenuation factor of the current (RAF) injected to the grid through the LCL network, the parameter of LCL can be clearly designed. The described LCL filter design method...
A novel digital phase-locked-loop (DPLL) method is proposed for single-phase grid-connected power generation systems in this paper. It consists of a grid voltage feed-forward network and a fictious instantaneous power feedback correction network. The fundamental signal of the grid voltage is extracted by a digital Butterworth filter to generate a unity sine reference signal for the feed-forward network,...
Grid-Connected power conditioning system (PCS) is widely used for distributed generation system. In Grid-Connected PCS, the LC filter is essential to reduce the current harmonics injected to the grid. In this paper adequate inductor core materials are selected to analyze the performance of 10 kW Grid-Connected Photovoltaic (PV) PCS. Core materials can be classified into three groups: power core, sheet...
Nowadays, hybrid cascade multilevel technology has attracted a increasing concern, especially in moderate-voltage and high-power applications. In this paper, a design method about how to design main circuits of active power filters(APF) with hybrid cascade multilevel structure is proposed. Through careful research, the combination of these cascade multilevel H-bridge modules is properly chosen and...
This work analyzes the compensation of harmonic currents through a Hybrid Filter. The Hybrid Filter consists of an active power filter connected in parallel with the inductor of a shunt passive tuned filter, resulting a lower voltage and current stress over the active filter. The paper investigates the behavior of an open loop control strategy, and discusses the dimensioning of the power converter...
In recent years, voltage and current harmonic problems by the remarkable development of static power converters with nonlinear characteristics have been one of the significant subjects. The authors propose the three phase power quality compensator with five leg circuit by indirect power conversion method. This system can compensate the line voltage harmonics by the series inverter and the load current...
In three-phase four-wire systems and unbalanced mode, the four-leg inverters have been considered as one of the adapted topologies of the power converters for the application which require a very strict and precise control of the neutral current, caused by the unbalanced and/or nonlinear load or unbalanced source. In this paper, we present a theoretical study of the control technique for this inverter...
The paper presents considerations how application of high power inverter-based power supply units affects supply conditions of industrial plants as well as how it influences power quality in MV power supply grids. Scope of the paper topics covers the effect of LC resonance that occurs between an output filter of the inverter, active compensating filters and inductances of the power supplying grid...
This paper presents a study about a single-phase shunt active power filter with sliding mode control. The operation mode of the shunt active filter is detailed, introducing a new operating mode for the inverter in order to improve the behavior of the line current during the zero-passings. Regarding sliding mode control, the sliding surface, the existence condition and the equivalent control are analysed...
For improving the dynamic response of the system, most of the pwm voltage source inverters are operating with inner current control loop. The application includes high performance ac drives, active filters and power supplies etc. Recently pwm voltage source inverters are employed in grid connected distributed power generating systems in order to provide secure and reliable power to the utility grid...
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