Three-phase

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

Comparison of standards for determining efficiency of three phase induction motors

Abstract: The paper describes a set of experiments and discusses their results for determining the efficiency of low voltage, three phase squirrel cage induction motors. The measured efficiency of an induction motor directly connected to the grid, strongly depends on the method used to evaluate the results and the standard according to which the measurements are performed. Different standards as IEEE 112 and IEC 32 are mentioned and their similarities and differences are discussed. The main discrepancies between the various standards is the way in which the values for the stray load losses are obtained at different load levels. A short description of the measurement setup is given and measurement results for motors of several manufacturers accounting for different standards are proposed. The results clearly demonstrate the necessity to handle the efficiency data given by the manufacturer with a lot of care.

Analysis and design of three-phase AC-to-DC converters with high power factor and near-optimum feedforward

Abstract: This paper presents a three-phase pulsewidth modulated AC-to-DC power converter with unity power factor and near-optimum dynamic regulation. A general mathematical model of the converter has been established to lead to a comprehensive analysis. The averaged small-signal technique is used to obtain the near-optimum feedforward compensator, thus resulting in the output impedance, and the audio susceptibility become zero, that is, the output voltage of the converter presented in this paper is independent of variations of the DC load current and the utility voltage. The proposed procedure of analysis is simple and effective, and it is also easy to implement. Finally, the theoretical formulations are verified both by simulated and experimental results in a 5 kW laboratory prototype system.

Harmonic reduction in a single-switch, three-phase boost rectifier with high order harmonic injected PWM

Abstract: A single-switch three-phase boost rectifier cannot be pushed to high power levels due to high total harmonic distortion (THD) An approach employing high order harmonic injected PWM is proposed to reduce the harmonic content to meet the IEC 555-2 (A) standard for a 5-10 kW power application without significantly increasing the output The results are verified by a prototype converter operating at 800 V/6 kW with a 3/spl times/220 V input

An arrangement for exchanging power

Abstract: An arrangement for exchanging power, in shunt connection, with a three-phase electric power network (1) comprises a Voltage Source Converter (5) having at least three phase legs (6-11) with each a series connection of switching cells (15). Each switching cell has at least two semiconductor assemblies (16, 17) connected in series and having each a semiconductor device (18) of turn-off- type and a rectifying element (19) connected in anti-parallel therewith and at least one energy storing capacitor (20). A control unit (41) is configured to control the semiconductor devices of each switching cell and to deliver a voltage across the terminals thereof being zero or U, in which U is the voltage across the capacitor. The control unit is also configured to calculate a value for amplitude and phase position for a second negative sequence-current or a zero-sequence voltage or a value of a dc current for which, when added to said three phase legs upon generation of a negative-sequence current, the resulting energy stored in the energy storing capacitors in each said phase leg will be constant and to control the semiconductor devices of said switching cells of the phase legs to add such a current or voltage to the currents and voltages, respectively, of each phase leg of the converter.

A Novel Three-Phase Diode Boost Rectifier Using Hybrid Half-DC-Bus-Voltage Rated Boost Converter

Abstract: A novel three-phase diode boost rectifier is proposed in this paper. The core of the proposed topology is a power conversion device [the loss-free transformer (LFT)] with two terminals; one input and one output. The input is parallel-connected with the dc bus capacitor, while the output is connected between the rectifier plus rail and the dc bus plus rail. The LFT is controlled in such a way to control the rectifier current and boost the dc bus voltage. In contrast to the ordinary boost rectifiers, the switches of the new boost rectifier are rated on a fraction of the dc bus voltage and a fraction of the input current. It makes this topology very compact and efficient. Power rating, size, and losses depend strongly on the ratio of the dc bus voltage to rectifier voltage (boosting factor). For example, if the boosting factor is low, below 1.5, the power converter efficiency could be 98-99%. The proposed boost rectifier has been analyzed and experimentally verified on a 5.5-kW prototype. The results are presented and discussed.