Three-phase

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

Space vector pulse-width modulation algorithm and DC-side voltage control strategy of three-phase four-switch active power filters

Abstract: A space vector pulse-width modulation (SVPWM) algorithm and a DC-side voltage control strategy for three-phase four-switch shunt active power filters are proposed. The basic principle of three-phase four-switch inverters to output three-phase balanced voltages is investigated in detail. Based on an advanced coordinate transformation, the proposed algorithm ensures basic voltage vectors to be right on the coordinate axes of αβ-coordinate system, which has the advantages of less computation and higher accuracy than the traditional. It synthesises zero vectors by equalising the duration time of two basic voltage vectors, which are equivalent in amplitude and opposite in phase, to simplify control logic and decrease harmonics of output voltages. To stabilise the DC bus voltage and balance the DC-side capacitor voltages, a DC-side voltage control strategy is presented. The former objective is obtained by controlling the active partition of the output currents, and the latter one by adapting the direct partition of phase C output current. An overall control method combining the proposed SVPWM algorithm with the DC-side voltage control strategy is presented. Experimental results have shown the validity and feasibility of the proposed algorithm and strategy.

Transistor bridge inverter motor drive having reduced harmonics

Abstract: A harmonic reduced pulse width modulation, variable speed transistor bridge inverter drive controls frequency and magnitude of stator voltage applied to an induction motor so as to maintain constant flux in the motor and permit maximum driving torque to be realized from the motor over a wide speed range. An oscillator generates a train of clock pulses whose frequency is proportional to an analog speed signal, and a three phase generator derives three phase reference waves having periods which include a predetermined number of clock pulses. A resettable volt/hertz integrator derives a train of ramp pulses which are synchronized to the clock pulses and vary in magnitude as a function of the integral of the output voltage from the bridge inverter with respect to time. The constant volt/hertz ramp signals are compared to first and second reference voltages to derive phase-displaced first and second control pulses. The fundamental output voltages of individual phases of the bridge are regulated in accordance with respective three phase reference waves, and pulse width modulating means switch the transistors in the phases of the bridge by two different width pulses whose leading edges are established by the clock pulses and whose trailing edges are respectively at the first and at the second control pulses and in such a manner that the bridge inverter applies twelve-step voltages to the motor stator windings in which the fifth and seventh harmonics are substantially eliminated and in which the voltage-to-frequency ratio is controlled to maintain constant flux in the motor.

Straight forward vector control of the Modular Multilevel Converter for feeding three-phase machines over their complete frequency range

Abstract: The paper presents a control strategy for the Modular Multilevel Converter (MMC), which allows feeding a three-phase machine over its complete frequency range. The machine is controlled by a standard field oriented control in the outer closed loop. The inner control has to met the challenge of balancing the energy stored in the capacitance of the converter arms. In this approach two operation modes are used: a low frequency mode for start-up and low speed operation plus a high frequency mode for higher speed. A special control scheme for the low frequency mode has to be applied to achieve low energy pulsation in the arm capacitances. It uses the common mode voltage of the three-phase machine together with inner circulating currents to ensure a symmetrical energy distribution in the arms of the MMC and to avoid any AC-currents in the DC-source.

Control of a Stand-Alone Variable Speed Wind Energy Supply System †

Abstract: This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG). The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and DC-link voltage, is used to maintain the DC-link voltage at a constant value. It is also used to make the batteries bank stores the surplus of wind energy and supplies this energy to the load during a wind power shortage. The load side voltage source inverter uses a relatively complex vector control scheme to control the output load voltage in terms of amplitude and frequency. The control strategy works under wind speed variation as well as with variable load. Extensive simulation results have been performed using MATLAB/SIMULINK.

A 50-kW Three-Phase Wireless Power Transfer System Using Bipolar Windings and Series Resonant Networks for Rotating Magnetic Fields

Abstract: The mass and volume of wireless power transfer (WPT) systems for charging electric vehicles are directly related to the rated power of the system. The difficulties of high-power wireless charging are exacerbated by the need to meet the same practical constraints associated with vehicle integration as lower power systems. Therefore, more advanced techniques are necessary to improve power density and specific power of wireless charging systems for high-power applications. This article presents theory and analysis of three-phase inductive WPT systems with bipolar phase windings. Magnetic coupler topologies and the theoretical and practical aspects of series three-phase resonant compensation networks are discussed. The systems under consideration are designed to utilize rotating magnetic fields to achieve a power transfer characteristic that is temporally smoother than single-phase systems. Other benefits associated with rotating magnetic field based WPT, including reduced ferrite mass, filter component requirements, and electromagnetic field emissions, are discussed. Experimental results of a prototype system are presented in both aligned and misaligned configurations. The system is demonstrated transferring 50 kW with 95% dc-to-dc efficiency over a 150-mm airgap in the aligned case. Onaper-pad basis, the magnetic couplers achieve a power density of 195 kW/m 2 and a specific power of 3.65 kW/kg. This article is accompanied by a video of the rotating magnetic field produced by a simulated three-phase WPT system.