Three-phase

About: Three-phase is a research topic. Over the lifetime, 16801 publications have been published within this topic receiving 159477 citations.

Digital signal processor implementation and performance evaluation of split capacitor, four-leg and three H-bridge-based three-phase four-wire shunt active filters

Abstract: In this paper a comprehensive study on the three-phase four-wire (3P4W) shunt active power filter (APF) is carried out on the basis of three system configurations. These three two-level voltage source inverter topologies are compared for 3P4W shunt APF, namely, split capacitor (2C), four-leg (4L) and three single-phase H-bridges (3HB). The performance of all three topologies, under an unbalanced non-linear load condition, is evaluated with a detailed digital signal processor (DSP)-based experimental investigation. The steady-state as well as dynamic performance of APF is studied to compensate for current harmonics, reactive power, current unbalance and neutral current. The advantages and limitations offered by each of the topologies are also discussed in brief.

A three-phase switched reluctance motor with two-phase excitation

Abstract: A new excitation strategy for a switched reluctance motor (SRM) is described and tested. This scheme excites two phases of an SRM simultaneously, which is similar to the two-phase excitation method of a step motor. In this scheme, the torque is produced by mutual-inductance as well as by self-inductance. The abrupt change of a phase excitation produces mechanical stresses, resulting in torque ripple and noise. The acoustic noise is reduced through a sequential two-phase excitation. Noise reduction occurs because the scheme reduces abrupt changes in excitation levels by distributed, balanced excitation and freewheeling during commutation. The operational principle and a characteristic comparison to that of the conventional SRM show that this novel excitation scheme has some advantages, including torque ripple and noise reduction, as well as simple inverter topology.

Power spectra of a PWM inverter with randomized pulse position

Abstract: Random pulse width modulation in static power converters results in the partial transfer of power from the discrete spectrum of the output voltage to the continuous spectrum, with advantageous effects on the operation of the supplied electromechanical systems. In this paper, a random PWM technique with randomized pulse position for three-phase voltage-controlled inverters is analyzed. Closed-form equations for the discrete and continuous power spectra of the line-to-line and line-to-neutral voltages of the inverter have been derived and confirmed by experiments. Presented theory opens the way to numerical optimization of the voltage spectra of randomly modulated inverters. >

Three phase load flow program

Abstract: The paper describes a general three phase load flow program developed for the steady state analysis of any electric transmission network under all possible imbalance conditions such as untransposed EHV lines, single phase loading, single pole switching, etc. Input data preparation and output data interpretation are made easy for program users by using both phase and symmetrical components quantities; however, the load flow problem formulation and solution are all done in phase quantities (A, B, C). The method of solution is the Newton-Raphson method, using optimally ordered triangular factorization to take advantage of the sparsity of network equations. The program has several new features to simulate real three phase operation of power systems and imbalance conditions. For example, the internal induced voltages of generators are balanced, while generator terminal voltages depend on internal machine impedances and the imbalance in machine currents. Also, the steady state performance of the voltage regulator is simulated to maintain some function of the machine terminal phase voltages constant, depending on the actual design of the voltage measurement. Another feature of the program is that it can handle all common transformer connections having two or three windings that are used in HV transmission networks.

Analysis of High-Efficiency Three-Phase Two- and Three-Level Unidirectional Hybrid Rectifiers

Abstract: This paper presents highly efficient three-phase high-power-factor hybrid rectifiers assembled by the parallel connection of a three-phase diode-bridge rectifier and series dc–dc boost converter with a two- or three-level unidirectional pulse width modulation (PWM) rectifier. The idea is to obtain a rectifier that is robust, highly efficient, and simple as a diode-based rectifier and also able to benefit from the PWM rectifier capability to reduce the line current harmonic content. Exemplary three-phase unidirectional hybrid systems built with a two-level delta-switch rectifier and three-level T-type or VIENNA six-switch rectifiers are suggested. Additionally, control schemes, which are appropriate for safeguarding the high-power-factor operation while improving the power sharing rating of the hybrid paralleled rectifier units and able to handle a phase loss without changing the controller structure, are proposed. In order to evaluate the studied hybrid rectifiers, first, an efficiency comparison between two- and three-level hybrid systems with conventional PWM rectifiers is performed. After that, the loss calculations are extended to a variable chip area to allow a fair comparison between these rectifiers. Interestingly, it is shown that the presented hybrid systems not only can achieve a higher efficiency but also require less silicon area than the single PWM rectifiers they are based on. Finally, experimental results obtained with an assembled unidirectional hybrid delta-switch rectifier prototype are presented in order to demonstrate the performance and advantages of this solution.