Sinusoidal Supply Research Articles

Comparison of Simple Control Strategies of Space-Vector Modulated Indirect Matrix Converter Under Distorted Supply Voltage

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper concerns the effect of symmetric supply voltage harmonics in a space-vector modulated three-phase indirect matrix converter (IMC). The IMC is modulated using indirect space-vector modulation. The effect of symmetric supply harmonics on load voltages and currents is analyzed using space-vector presentation. The measurement and simulation results with distorted supply voltages are compared to the results with pure sinusoidal supply voltage. Four simple control methods of IMC are tested in simulations and measurements: 1) open-loop control without measurements (Method I); 2) calculation of modulation index using measured supply voltages (Method II); 3) closed-loop control of output currents (Method III); and 4) combination of Methods II and III, i.e., closed-loop output current control with supply voltage measurement (Method IV). All the methods are easy to implement and do not require complicated computing. It is noted that Methods II and IV, where modulation index is calculated using measured supply voltage magnitudes, can produce more sinusoidal load currents than Methods I and III, which suppose ideal supply conditions. </para>

A Unity-Power-Factor Converter Using the Synchronous-Reference-Frame-Based Hysteresis Current Control

In this paper, a high-performance unity-power-factor rectifier-inverter structure is presented. A synchronous-reference-frame-based hysteresis current control as inner loop and dc-link voltage control as outer loop are adopted for the front-end converter. With the proposed control algorithm, the converter draws high-quality sinusoidal supply currents and maintains good dc-link-voltage regulation under wide load variation, and even under unbalanced and nonsinusoidal supply voltage conditions. Theoretical results of its analysis are verified initially through digital simulation. Finally, experimental results of a 1-kVA laboratory prototype system confirm the feasibility of the proposed technique

Modeling and Characterization of Induction Motor Internal Faults Using Finite-Element and Discrete Wavelet Transforms

This paper examines the behavior of a three-phase induction motors with internal fault conditions under sinusoidal and nonsinusoidal supply voltages. This includes two types of faults, rotor broken bar and stator faults. Early detection and diagnosis of these faults are desirable for condition assessment, maintenance schedule, and improved operational efficiency of induction motors. The terminal behavior of the induction motor was investigated by coupling the induction motor transient finite-element (FE) model and external electric circuit. Such a model would allow the efficient representation of the induction machine with internal faults. A discrete wavelet transform (DWT) was then used to extract the different harmonic components of the stator currents. The key advantages of the DWT are its ability to provide a local representation (in both time and frequency) of the current signal for normal and faulty modes, and its applicability to nonstationary signals

Current-source-rectifier topologies for sinusoidal supply current: theoretical studies and analyses

For current-source-rectifier (CSR)-based systems, sinusoidal supply current and unity displacement power factor in the utility are achieved through either a pulsewidth-modulation CSR or a phase-controlled rectifier in conjunction with an active filter. This paper investigates theoretical studies and analyses for the two topologies from the standpoint of converter kilovoltampere rating and switch rating.

Single-phase full-wave rectifier study with experimental measurements

This paper studies experimentally the harmonic absorbed currents by single-phase rectifiers under sinusoidal supply voltage conditions. Laboratory tests have been developed with a rectifier supplied with non-distorted voltages to characterize its absorbed harmonic currents (magnitude and phase angle). From these results, a database that characterizes rectifier harmonic behavior experimentally and allows the rectifier currents to be easily calculated is proposed. The database applicability is experimentally studied in three laboratory tests.

Behavior of three-phase induction motors with variable stator coil winding pitch

A pulse-width modulation (PWM) inverter and sinusoidal output voltage supplies feeding four different chorded three-phase induction motors were tested for low-order odd voltage harmonic components and efficiency at different loads. The total harmonic distortion due to the third, fifth, and ninth harmonics was lowest in a motor with 160° coil pitch energized by both sinusoidal and PWM voltages. The efficiencies of the motor with the short-chorded winding were as much as 5% and 16% higher than that of the full-pitched motor under sinusoidal and PWM excitation, respectively, due to harmonic cancellation.

Finite-element-based nonlinear physical model of iron-core transformers for dynamic simulations

A finite-element (FE)-based transformer physical phase variable model is proposed. In this model, the effects of nonlinear magnetization on inductances are included by considering the inductance variations with the amplitude of the ac flux as well as its phase angle during a complete ac cycle. Such a consideration is represented by 2-D inductance tables. The magnetizing currents at various magnetization levels are used to calculate the inductances then build the table. The magnetizing currents are determined using circuit-coupled FE analysis of the transformer with sinusoidal voltage supplies. The structure of the inductance table is given and the procedure of inductance table lookup during dynamic simulation is provided. Simulink implementation of the FE-based transformer phase variable model is performed. The validity of the presented technique is verified through comparing the magnetizing current waveforms obtained from the FE-based phase variable model and those from an FE model. The significance of the proposed FE-based phase variable model is in its accuracy and its applicability for dynamic simulation of interconnected components in a power system

Instantaneous Reactive Power p-q Theory and Power Properties of Three-Phase Systems

This paper investigates how power phenomena and properties of three-phase systems are described and interpreted by the Instantaneous Reactive Power (IRP) p-q Theory. This paper demonstrates that this theory misinterprets power properties of electrical systems or provides some results that at least defy a common sense or meaning of some notions in electrical engineering. For example, it suggests the presence of an instantaneous reactive current in supply lines of purely resistive loads and the presence of an instantaneous active current in supply lines of purely reactive loads. Moreover, it suggests that line currents of linear loads with sinusoidal supply voltage contain a nonsinusoidal component. This paper shows, moreover, that the IRP p-q Theory is not capable to identify power properties of three-phase loads instantaneously. A pair of instantaneous values of p and q powers does not allow us to conclude whether the load is resistive, reactive, balanced, or unbalanced. It is known that a load imbalance reduces power factor. However, the IRP p-q Theory does not identify the load imbalance as the cause of power factor degradation.

Comparison of Stray Load and Inverter-Induced Harmonic Losses in Induction Motors Using Calorimetric and Harmonic Injection Methods

This paper addresses two types of additional losses in induction motors. One is stray load loss resulting from loss segregation when induction motors operate from a sinusoidal supply voltage and the other is harmonic loss when induction motors operate from inverter-fed supply voltage. Both losses are of concern in machine design and operation but they are difficult to predict accurately without the use of empirical factors. This is due to their complex loss mechanisms and small magnitudes relative to output power for high efficiency machines. Compared to total machine power loss, however, they are a significant source of loss. Investigation into the correlation of the two loss components could enable effective quality control of the manufacturing of machines for use on inverter supplies. With the availability of advanced calorimetric and harmonic injection techniques, it becomes possible for these small loss components to be measured with precision. In this paper, seven induction motors ranging in power through 1.1, 7.5, 15 to 30 kW are tested for experimental comparison. Among these are four 7.5 kW machines. Test results suggest there is a need for induction motors designed specifically for inverter-fed operation.

A SIMPLE FUZZY LOGIC SPEED CONTROLLER FOR A DC MOTOR FED BY SEPIC CONVERTER

This paper presents a closed loop speed controi of a separately excited DC motor. A cascade combination of a diode bridge rectifier and single-ended primary inductor converter (SEPIC) is used to feed the DC motor from an AC supply. This circuit combination offers both step-up and step-down characteristics of the motor terminal voltage as well as an approximately sinusoidal supply current with an improved power factor. A fuzzy logic speed controller is used to overcome any system nonlinearity and parameter changes. Also. a wide range of both speed and load changes with satisfactory response is obtained. Two fuzzy membership functions are used reflecting few and simple control rules. Moreover. a genetic algorithm (GA) is used to optimally tune the fuzzy controller parameters. Simulation results of the system are obtained by solving the differential equations in different modes of operation. The system is laboratory implemented and the controller is investigated using a digital signal processing board (DSPI 104). The experimental and simulation results are verified and a correlation between both has been found. The results confirm the relevance of the proposed configuration a- a useful rectifier that achieves sinusoidal supply current, high power factor and motor speed regulator.

A time domain small transformer model under sinusoidal and non-sinusoidal supply voltage

In this paper a numerical technique for generating the instantaneous magnetization characteristic and the instantaneous core loss characteristic of a single-phase transformer is proposed. The hysteresis loop is described by the instantaneous core loss resistance R(t), and the instantaneous magnetizing inductance L(t). This time domain transformer model is applied to calculate the excitation current under sinusoidal and non-sinusoidal supply voltage. These results are compared to those simulated by ATP obtaining a significant improvement. The excitation current determined by the instantaneous parameters R(t) and L(t) fits the experimental data accurately. Copyright © 2005 John Wiley & Sons, Ltd.

Luminescence of argon in a spatially stabilized mono-filamentary dielectric barrier micro-discharge: spectroscopic and kinetic analysis

The experimental work reported here is devoted to the temporal behaviour of a mono-filamentary dielectric barrier discharge in pure argon, from 100 to 700 Torr. A sinusoidal voltage supply is used, its frequency ranging from 10 to 90 kHz. An anode avalanche followed by a cathode streamer as well as the spatial stability of the micro-discharge is clearly seen in successive 3-ns snapshots in the visible range. Near the cathode, its diameter is about 0.2 mm, at 400 Torr. The electrical characteristics of the discharge are also evaluated, in particular the breakdown voltage and the energy deposited in the micro-discharge. The light output in the vacuum ultraviolet range is essentially due to the second continuum of argon, centred at 130 nm. The kinetic study of this continuum shows that primary excitation of the lowest argon atomic 4s and 4s′ states is practically achieved after 120 ns since beyond that time the luminescence decay of the second continuum is fairly described by only two exponential terms. So collisions between excited states, electronic collisions, and recombination of ionic species do not contribute significantly to this luminescence, after 120 ns. Surprisingly, we do not observe the contribution of the Ar(3P1) resonant state in the production of the argon excimers. The radiative lifetime of the Ar2[1u(3P2)]low v excimer ((3.18 ± 0.03) µs) and the three-body rate constant relative to the decay of the Ar(3P2) metastable state ((13.2 ± 0.9) Torr−2 s−1) leading to the formation of Ar2[1u(3P2)], are estimated. These results are consistent with those found from the literature. A simple kinetic scheme is proposed for times later than 120 ns.

On Some Misinterpretations of the Instantaneous Reactive Power&amp;lt;tex&amp;gt;$phbox-q$&amp;lt;/tex&amp;gt;Theory

The main features of the instantaneous reactive power (IRP) p-q theory, considered as a power theory of three-phase systems, are analyzed in this paper using the theory of the currents' physical components (CPC). This analysis shows that the p and q powers are not associated with separate power phenomena, but with multiple phenomena. Moreover, the results of the IRP p-q theory contradict some common interpretations of power phenomena in three-phase circuits. Namely, according to the IRP p-q Theory the instantaneous reactive current can occur even if a load has zero reactive power, Q. Similarly, the instantaneous active current can occur even if a load has zero active power, P. Moreover, these two currents in circuits with a sinusoidal supply voltage can be nonsinusoidal even if there is no source of current distortion in the load. The analysis shows that a pair of values of instantaneous active and reactive p and q powers does not enable us to draw any conclusion with respect to the power properties of three-phase unbalanced loads even in a sinusoidal situation. Thus, the instantaneous reactive power p-q theory does not identify power properties of such loads instantaneously. This conclusion may have an importance for control algorithms of active power filters. The paper reveals the relationship between the p and q powers and the active, reactive and unbalanced powers, P, Q, and D and specifies the required energy storage capability of active power filters operated under sinusoidal unbalanced conditions.

Non-Linear and Unbalanced Three-Phase Load Static Compensation with Asymmetrical and Non Sinusoidal Supply

Non-Linear and Unbalanced Three-Phase Load Static Compensation with Asymmetrical and Non Sinusoidal Supply

Three-Phase Synchronous PWM for Flyback Converter With Power-Factor Correction Using FPGA ASIC Design

The design and development of a synchronous pulsewidth modulation (PWM) generator suitable for the three-phase flyback converter with transformer isolated and power-factor correction using a field-programmable gate array is proposed. The proposed three-phase synchronous PWM makes it possible for the converter to obtain the sinusoidal supply currents with a near-unity power factor. A high-frequency transformer is considered in the design to provide galvanic isolation and serves the dual role of inductor and transformer. Results are provided to demonstrate the effectiveness of the design.

An introduction to the vector potential

We present a review and discussion of the physical meaning of the vector potential inelectromagnetism by means of a classical experiment in which a long solenoid, connected toa sinusoidal voltage supply, produces an electric field and a vector potential in a circuitexterior to the solenoid itself. Some basic considerations are recalled concerning themeaning of action-at-a-distance and local description, in terms of ‘real fields’ of the inducedelectromotive force on the circuit outside the solenoid. From this viewpoint theroles played by the magnetic field, the electric field and the vector potential toaccount for the physical effects are reviewed. Finally, the connections betweenthese considerations and the magnetic Aharonov–Bohm effect are recalled in thelight of recent theoretical work aimed at explaining the Aharonov–Bohm phaseshift in terms of the magnetic field without resorting to the vector potential.

Additional no-load losses in inverter-fed high-speed cage induction motors

An analysis of additional high-frequency losses in high-speed cage induction motors with closed rotor slots under sinusoidal and inverter supply at no load is presented. Calculated losses are compared with experimental results obtained by measurement on a 270 kW, 16,200/min, prototype motor, at both the delta and star connections of the stator winding. The main additional losses of the prototype motor investigated due to inverter supply are eddy current losses in the stator winding. Both measurement and calculation show that, at the delta connection, the additional losses are higher due to the lower modulation degree of the inverter, causing higher harmonic voltage amplitudes.

Design of a compact hysteresis motor used in a gyroscope

This paper presents the computer-aided design and test results of a compact three-phase hysteresis synchronous motor used as the drive motor of a gyroscope. Hysteresis motor is the best choice for this application because of its compactness and reliability. Also, it has a self-starting capability and it does not require any position sensor and commutation circuits. The design of a three-phase 32-V 400-Hz 6000-r/min hysteresis motor in full is presented. A computer program in MATLAB is created for the design and analysis of the hysteresis motor and used extensively in this work. The test results of the developed motor are fairly matching with the computed values. Results of a detailed study conducted to identify the harmonic torque components reveal that the net torque available with a six-pulse inverter supply is only 92.89% of that with a sinusoidal supply.

Improved controller for power conditioner using high-temperature superconducting magnetic energy storage (HTS-SMES)

One of the most important functions in a superconducting magnetic energy storage (SMES) system when used for power conditioning, is the ability to charge the super-conducting coil as fast as possible to ensure that it is ready when it is next required. This paper describes a novel controller for a high-temperature SMES (HTS-SMES) that can ensure: 1) fast return of energy to the superconducting coil under constant-current mode and 2) a constant and sinusoidal input supply current irrespective of the varying load demand with and without harmonics. In the new HTS-SMES proposed, two hysteresis controllers are used, one to control the magnitude, phase and the waveform of the ac supply current, and the other is to control a dc chopper to regulate the SMES coil current. The first hysteresis controller ensures that as far as the power utility is concerned, the load appears to the utility system as a constant sinusoidal load with unity power factor irrespective whether the load is distorted or varying in nature. The second hysteresis controller has been designed to regulate the energy in and out of the superconducting coil. A special feature of this controller is its ability to smoothly charge the superconducting coil using constant current charging so that it can be ready for the next discharging operation as soon as possible. Analysis of the circuit operation under hysteresis control is presented in details. Simulation and experimental results are presented demonstrating the feasibility of the proposed power conditioning system.

Predicting iron losses in soft magnetic materials with arbitrary voltage supply: an engineering approach

We propose a new approach for predicting iron losses in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with a sinusoidal or pulsewidth modulation supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents, and excess losses with the two supplies. Since any contribution depends on the voltage supply characteristics, it is possible to find a direct mathematical relationship between the iron loss contribution and the voltage supply characteristics. As a consequence, an iron loss prediction can be obtained with any voltage supply if it does not produce a hysteresis minor loop. The energetic model is based on coefficients that depend on the magnetic material characteristic. We performed an accurate analysis of the model on eight magnetic materials used for electrical machine construction, of different thicknesses and alloy compositions. In this way, we found the main coefficients for a large spread of magnetic materials. As a consequence, our approach can be a useful support for electrical machine designers when the energetic performance of a magnetic material has to be predicted for a voltage supply different from the sinusoidal one.