Three-phase

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

Small-signal modeling and control of three-phase PWM converters

Abstract: The paper presents a systematic approach to small-signal modeling, and control design of three-phase PWM converters. The well established design procedures used in DC-DC converter control design, are adapted for the three-phase converter control based on the similarity in the small-signal dynamics of the three-phase converters and their DC-DC counterparts. The approach is especially beneficial in three-phase rectifier control, which is reduced to a single-input single-output system after closing the current loops. The modeling approach is verified on a 10 kW three-phase boost rectifier switching at 15.6 kHz with DSP control. A wide-bandwidth output voltage control loop is then designed based on the verified small-signal transfer functions. >

DC bus voltage balancing and control in multilevel inverters

Abstract: A multilevel inverter system having four or more levels of output voltage on each inverter output line. The voltage across each of three or more series connected DC bus capacitors is provided to an inverter which is formed to have redundant switching states, such as a plurality of controlled switching devices and diodes connected in a diode-clamped multilevel inverter configuration. The switching of the switching devices is controlled to provide a selected output voltage waveform utilizing redundant switching states, when such states are available on each voltage transition, by selecting a one of the available switching states that serves to provide the desired phase-to-phase voltages and to tend to equalize the voltages across the DC bus capacitors. Active or passive rectifiers may be used to provide the DC voltage across the DC bus lines and across the DC bus capacitors. Separate rectifiers may be provided for each capacitor which are supplied from secondaries of transformers connected to the three phase input lines to provide isolation and voltage level adjustment. The multilevel inverter system provides output voltage waveforms with lower total harmonic distortion that conventional two or three level inverters, while maintaining voltage balance across the several DC bus capacitors.

Modulation for Three-Phase Transformerless Z-Source Inverter to Reduce Leakage Currents in Photovoltaic Systems

Abstract: In this paper, a modified Z-source inverter (ZSI) with specific modulation techniques is proposed to reduce leakage currents in three-phase transformerless photovoltaic (PV) systems. The new topology only requires an additional fast-recovery diode when compared with the original structure. On the other hand, the pulsewidth modulation technique is entirely modified in order to reduce the leakage currents through the conduction path. Simulation results for the three-phase transformerless PV system operating in two cases, i.e., connected to a grid and connected to a grounded RL load, are presented. Experimental results of leakage currents in three-phase ZSIs connected to a RL load are obtained to validate the theoretical and simulation models.

Improved Voltage-Vector Sequences on Dead-Beat Predictive Direct Power Control of Reversible Three-Phase Grid-Connected Voltage-Source Converters

Abstract: This paper presents a dead-beat predictive direct power control (DPC) strategy and its improved voltage-vector sequences for reversible three-phase grid-connected voltage-source converters (VSCs). The instantaneous variation rates of active and reactive powers, by applying each converter voltage vector in 12 different sectors, are deduced and analyzed. Based on the power variation rates, it is found that the values of the predicted duration times for the two conventional active converter voltage vectors are less than zero when the grid-connected VSC operates as either a rectifier or an inverter. In order to solve this issue, two new alternative vector sequences are proposed and compared. Experimental results on a 1.5 kW reversible grid-connected VSC system are presented to validate the feasibility of the proposed voltage-vector sequences on the dead-beat predictive DPC strategy.