Three-phase

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

A novel modeling and control method for three-phase PWM converters

Abstract: The pulse-width modulated (PWM) voltage-source converter (VSC) and current-source converter (CSC) are the building blocks of most of the switch-mode power electronic systems. Irrespective of the converter type, the controller is supposed to fulfill two objectives: (1) real power flow control which leads to the regulation of the DC quantity (DC voltage in VSC and DC current in CSC), and (2) reactive power flow control on the AC-side. The major difficulty in control is caused by the nonlinearities in the converter model. The existing control techniques are based on the design of the PI-controllers without the knowledge of the converter model, linearizing the nonlinear model, or splitting the original system into linear and nonlinear parts and dealing with them separately. In this paper, a power balance equation and nonlinear input transformation are used to derive a linear model from the original nonlinear model. Then, a decoupled state-feedback control method is applied to the new model. The accuracy of the new model and the performance of the applied control method are evaluated using the simulation results obtained from the PSCAD/EMTDC simulation package. It is shown that as a result of using the new model and applying the state-feedback control technique, the dynamics of the system are considerably improved resulting in short response times. It is also shown that the approach taken in modeling and control results in excellent results even at low switching frequencies making the scheme very suitable for high-power applications.

EMI Reduction Methods in Wireless Power Transfer System for Drone Electrical Charger Using Tightly Coupled Three-Phase Resonant Magnetic Field

Abstract: Wireless power transfer (WPT) technology is a promising way for convenient and safe battery charging without any electrical contact, which may cause an unwanted electric spark or deliver dangerous electric current to the users. When transferring power from the source to the battery, strong electromagnetic fields (EMFs) are generated. Moreover, the inverter output contains a wide range of harmonics. Therefore, it is important to reduce the EMFs and electromagnetic interference (EMI) in a WPT system. For the first time, in this paper, we propose a new tightly coupled three-phase resonant magnetic field (TC-TPRMF) charger for a drone operating at 60 kHz, which can completely eliminate the third harmonic and its integer multiples in the output voltage. Furthermore, to reduce the selective EMI, the conduction angle control is proposed for the WPT charging system. Through a series of measurements, we verified that the proposed TC-TPRMF with the conduction angle control can reduce the seventh and 11th harmonics of the Tx current by 6.08 and 11.84 dBμA, respectively. The coil-to-coil power transfer efficiency and total system power transfer efficiency are maintained at 91% and 72%, respectively.

Unified constant-frequency integration control of three-phase standard bridge boost rectifiers with power-factor correction

Abstract: In this paper, a three-phase six-switch standard boost rectifier with unity-power-factor correction is investigated. A general equation is derived that relates the input phase voltages, output DC voltage, and duty ratios of the switches in continuous conduction mode. Based on one of the solutions and using one-cycle control, a unified constant-frequency integration controller for PFC is proposed. For the standard bridge boost rectifier, a unity power factor and low total harmonic distortion can be realized in all three phases with a simple circuit that is composed of one integrator with reset along with several flips-flops, comparators, and some logic and linear components. It does not require multipliers and three-phase voltage sensors, which are required in many other control approaches. In addition, it employs constant-switching-frequency modulation that is desirable for industrial applications. The proposed control approach is simple and reliable. All findings are supported by experiments.

Stability Improvement for Three-Phase Grid-Connected Converters Through Impedance Reshaping in Quadrature-Axis

Abstract: Three-phase AC−DC and DC−AC power converters have been extensively employed as grid-interfaces in various applications, e.g., distributed generation and energy storage systems. In these applications, power converters should always synchronize with the mains grid so that active and/or reactive power can properly be regulated while maintaining desired waveforms of grid currents. Grid synchronization necessitates accurate information of grid voltages, which is normally obtained through phase-locked-loops (PLLs). However, the employment of PLLs may bring in stability concerns. Previous research revealed that the inclusion of PLLs shapes the impedance of power converters into a negative resistance in the quadrature-axis ( q -axis), and this should be responsible for instability. To resolve the instability issue caused by PLLs, this paper proposes an impedance controller for reshaping the q -axis impedance into a positive resistance in the low-frequency band. Without any extra burden on system hardware, the proposed controller can easily be implemented by directly relating the q -axis voltage to the q -axis current reference. As a result, the presented three-phase power conversion system can operate stably even under a severely weak grid condition, which are verified by simulation and experimental results.

Third-harmonic modulated power electronics interface with three-phase utility to provide a regulated DC output and to minimize line-current harmonics

Abstract: A novel approach to achieving nearly sinusoidal line current rectification of three-phase utility voltages is presented. The scheme incorporates two step-up DC-DC power converters to modulate the DC link currents at the third harmonic frequency. The modulated currents are then reinjected on the AC side of the diode bridge rectifier. Simulation results for a three-phase, 208 V (line-to-line), 3 kW system are presented. The sensitivity of the interface to unbalances in various system parameters is included. Results from experimental investigations on a small-scale laboratory model are presented. >