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 hysteresis current control for three-phase three-level PWM rectifiers

Abstract: A novel hysteresis current control concept for three-phase three-level PWM rectifiers is presented. The proposed control is based on a virtual connection of the output center point and the mains star point and achieves a decoupling of the three phases. This control technique, besides having the advantages of a classical hysteresis control, provides a more regular switching of the power transistors and an intrinsic stability of the output center point voltage, and allows a full utilization of the modulation range. The novel control concept is discussed and compared to conventional current control techniques. Furthermore, the current control is digitally implemented and experimental results for controlling a Vienna rectifier are presented.

PLL-Less Active Power Filter Based on One-Cycle Control for Compensating Unbalanced Loads in Three-Phase Four-Wire System

Abstract: In this paper, a shunt active power filter (APF) based on unified constant frequency integration or one-cycle control (Smedley et al., 2001) for compensating unbalanced loads in a three-phase four-wire system is explored. The APF provides compensation currents in such a way that the utility supplies only the balanced fundamental current at unity power factor, even if the load draws reactive and harmonic currents. The scheme neither requires the service of a phase-locked loop nor requires to sense the utility voltages. This makes the scheme insensitive to the distortions that are generally present in the utility voltages. First, the one-cycle control technique is applied to a topology involving a four-leg converter for the proof of concept. Then it is utilized to control a conventional three-leg converter having a split-capacitor dc link. The effectiveness and the viability of the schemes are demonstrated through detailed simulation and experimental verification.

Three-phase grid-connected photovoltaic system with SVPWM current controller

Abstract: Effective control strategies for reliable photovoltaic (PV) grid-connected systems are needed to efficiently use solar energy, an abundant and clean renewable energy source. A space vector pulse width modulation (SVPWM) has been widely applied in the current control of three-phase voltage source inverters (VSIs). The control strategy combines a constant voltage tracking method for the variable photovoltaic power with SVPWM-based proptional-intergral (PI) current controller in a single stage three-phase PV grid-connected system. The controller mimics deadbeat control in the synchronous d-q reference frame, and is very simple and robust to implement. With the necessary grid voltage detection in Photovoltaic systems for protection, grid harmonics disturbance is effectively suppressed through feed-forward compensation. The simulation results show that the current controller makes the PV grid-connected VSI output current to be in phase with the grid voltage and has an excellent steady-state response as well as an extremely fast dynamic response.

Multi-speed motor controller

Abstract: Three phase sinusoidal waveforms generated from a DC bus voltage using Space Vector PWM method are used to obtain multi-speeds from a 3 Phase AC Induction motor. A novel algorithm generates the switching signals from a micro controller to drive the power devices of the Inverter Bridge, the output of which is applied to the motor. At different speeds, below the rated voltage of the motor, the output voltage V and the frequency f are maintained to keep V/f constant so that the motor torque is kept constant. At above the rated voltage of the motor, only the frequency is increased to obtain constant output from the motor at increased speeds.

A novel control concept for reliable operation of a three-phase three-switch buck-type unity-power-factor rectifier with integrated boost output stage under heavily unbalanced mains condition

Abstract: In this paper the reliable operation of a three-phase three-switch buck-type pulsewidth-modulation unity-power-factor rectifier with integrated boost output stage under heavily unbalanced mains, i.e., mains voltage unbalance, loss of one phase, short circuit of two phases, or earth fault of one phase is investigated theoretically and experimentally. A brief description of the principle of operation and the most advantageous modulation method are given. The analytical calculation of the relative on-times of the active switching states and of the dc-link current reference value is treated in detail for active and deactivated boost output stage. Based on the theoretical considerations a control scheme which allows for controlling the system for any mains condition without changeover of the control structure is described. Furthermore, digital simulations as well as experimental results are shown which confirm the proposed control concept for different mains failure conditions and for the transition from balanced mains to a failure condition and vice versa. The experimental results are derived from a 5-kW prototype (input voltage range (280...480) V/sub rms/ line-to-line, output voltage 400 V/sub DC/) of the rectifier system, where the control is realized by a 32-bit digital signal processor.