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Showing papers on "Inverter published in 2001"


Journal ArticleDOI
09 Nov 2001-Science
TL;DR: This work demonstrates logic circuits with field-effect transistors based on single carbon nanotubes that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
Abstract: We demonstrate logic circuits with field-effect transistors based on single carbon nanotubes. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p-doping to n-doping and the study of the nonconventional long-range screening of charge along the one-dimensional nanotubes. The transistors show favorable device characteristics such as high gain (>10), a large on-off ratio (>10(5)), and room-temperature operation. Importantly, the local-gate layout allows for integration of multiple devices on a single chip. Indeed, we demonstrate one-, two-, and three-transistor circuits that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.

2,642 citations


Journal ArticleDOI
TL;DR: If simplified by the proposed method, all the remaining procedures necessary for the three-level SVPWM are done like conventional two-level inverter and the execution time is greatly reduced and the DC-link neutral-point potential control algorithms are implemented more easily.
Abstract: In this paper, a new simplified space-vector pulse width modulation (SVPWM) method for a three-level inverter is proposed. This method is based on the simplification of the space-vector diagram of a three-level inverter into that of a two-level inverter. If simplified by the proposed method, all the remaining procedures necessary for the three-level SVPWM are done like conventional two-level inverter and the execution time is greatly reduced. The DC-link neutral-point potential control algorithms are implemented more easily. The proposed method can be applied to the multi-level inverters above three-level. The validity of the new SVPWM method is verified by experiment with a 1000 kVA three-level insulated gate bipolar transistor (IGBT) inverter.

525 citations


Journal ArticleDOI
30 Sep 2001
TL;DR: In this paper, a pure integrator is employed for stator flux estimation, which permits high estimation bandwidth and compensates the offset and drift components in the acquired feedback signals, voltage distortions caused by the nonlinear behavior of the switching converter and increased sensitivity against model parameter mismatch.
Abstract: The performance of vector-controlled induction motor drives without a speed sensor is generally poor at very low speed. The reasons are offset and drift components in the acquired feedback signals, voltage distortions caused by the nonlinear behavior of the switching converter, and the increased sensitivity against model parameter mismatch. New modeling and identification techniques are proposed to overcome these problems. A pure integrator is employed for stator flux estimation which permits high-estimation bandwidth. Compensation of the drift components is done by offset identification. The nonlinear voltage distortions are corrected by a self-adjusting inverter model. A further improvement is a novel method for online adaptation of the stator resistance. Experiments demonstrate smooth steady-state operation and high dynamic performance at extremely low speed.

399 citations


Journal ArticleDOI
TL;DR: In this paper, a new approach to the direct torque control (DTC) of induction motor drives is presented, where the inverter switching frequency is constant and dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency dither signal.
Abstract: In this paper, a new approach to the direct torque control (DTC) of induction motor drives is presented. In comparison with the conventional DTC methods, the inverter switching frequency is constant and is dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency dither signal. The well-developed space vector modulation technique is applied to inverter control in the proposed DTC-based induction motor drive system, thereby dramatically reducing the torque ripple and speed ripple. As compared to the existing DTC approach with constant inverter switching frequency, the presented new approach does not invoke any concept of deadbeat control, thereby dramatically reducing the computations. Experimental results are illustrated in this paper confirming that the proposed DTC method has the above-mentioned features even at the low speed range down to /spl plusmn/1 r/min.

381 citations


Proceedings ArticleDOI
17 Jun 2001
TL;DR: In this paper, the use of active neutral point clamp switches in a three-level NPC voltage source inverter is investigated to balance the losses among the semiconductors, which enable a substantially increased output power of the inverter and an improved performance at zero speed.
Abstract: This paper investigates the use of active neutral point clamp switches in a three-level NPC voltage source inverter to balance the losses among the semiconductors. Both a control structure and algorithm are proposed which enable a substantially increased output power of the inverter and an improved performance at zero speed.

250 citations


Journal ArticleDOI
TL;DR: In this paper, a p-type metal-oxide-semiconductor (PMOS) and complementary CMOS (CMOS) inverters based on single-walled carbon nanotube field effect transistors are presented.
Abstract: This letter presents p-type metal–oxide–semiconductor (PMOS) and complementary metal–oxide–semiconductor (CMOS) inverters based on single-walled carbon nanotube field-effect transistors. The device structures consist of carbon nanotubes grown via a chemical-vapor deposition method and contacted by two metallic source/drain electrodes. Electrical properties of both p-type (without doping) and n-type nanotube transistors with potassium doping have been measured. By utilizing a resistor as the load for a p-type nanotube field-effect transistor, a PMOS inverter is demonstrated. Furthermore, by connecting a p-type nanotube transistor and an n-type nanotube transistor, a CMOS inverter is demonstrated. Both types of inverters exhibit nice transfer characteristics at room temperature. Our work represents one step forward toward integrated circuits based on nanoelectronic devices.

233 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the threshold voltage instabilities of all-organic thin-film transistors as a function of stress time and stress bias and found that the dominant effect is a positive threshold shift for negative gate bias stress which is explained by mobile ions drifting in the insulator when a gate field is applied.
Abstract: Threshold voltage instabilities of all-organic thin-film transistors are investigated as a function of stress time and stress bias. The dominant effect is a positive threshold shift for negative gate bias stress which is explained by mobile ions drifting in the insulator when a gate field is applied. Trapping of charge carriers at the semiconductor–insulator interface plays only a minor role. Furthermore, we investigate the stress behavior of a basic logic element, an inverter. In comparison to a single transistor, we observe improved stability which arises from partial compensation of the parametric shifts during operation.

212 citations


Journal ArticleDOI
TL;DR: A plug-in digital repetitive leaning control scheme is proposed for three-phase constant-voltage constant-frequency (CVCF) pulsewidth modulation inverters to achieve high-quality sinusoidal output voltages.
Abstract: In this paper, a plug-in digital repetitive leaning control scheme is proposed for three-phase constant-voltage constant-frequency (CVCF) pulsewidth modulation inverters to achieve high-quality sinusoidal output voltages. In the proposed control scheme, the repetitive controller (RC) is plugged into the stable one-sampling-ahead-preview-controlled three-phase CVCF inverter system using only two voltage sensors. The RC is designed to eliminate periodic disturbance and/or track periodic reference signal with zero tracking error, The design theory of plug-in repetitive learning controller is described systematically and the stability analysis or overall system is discussed. The merits of the controlled systems include features of minimized total harmonic distortion, robustness to parameter uncertainties, fast response, and fewer sensors. Simulation and experimental results are provided to illustrate the effectiveness of the proposed scheme.

204 citations


Journal ArticleDOI
30 Sep 2001
TL;DR: A neural network based implementation of space vector modulation (SVM) of a three-level voltage-fed inverter of a DSP based modulator has been proposed in this paper that fully covers the linear undermodulation region.
Abstract: A neural-network-based implementation of space-vector modulation (SVM) of a three-level voltage-fed inverter is proposed in this paper that fully covers the linear undermodulation region. A neural network has the advantage of very fast implementation of an SVM algorithm, particularly when a dedicated application-specific IC chip is used instead of a digital signal processor (DSP). A three-level inverter has a large number of switching states compared to a two-level inverter and, therefore, the SVM algorithm to be implemented in a neural network is considerably more complex. In the proposed scheme, a three-layer feedforward neural network receives the command voltage and angle information at the input and generates symmetrical pulsewidth modulation waves for the three phases with the help of a single timer and simple logic circuits. The artificial-neural-network (ANN)-based modulator distributes switching states such that neutral-point voltage is balanced in an open-loop manner. The frequency and voltage can be varied from zero to full value in the whole undermodulation range. A simulated DSP-based modulator generates the data which are used to train the network by a backpropagation algorithm in the MATLAB Neural Network Toolbox. The performance of an open-loop volts/Hz speed-controlled induction motor drive has been evaluated with the ANN-based modulator and compared with that of a conventional DSP-based modulator, and shows excellent performance. The modulator can be easily applied to a vector-controlled drive, and its performance can be extended to the overmodulation region.

201 citations


Journal ArticleDOI
TL;DR: In this paper, a digital control technique for the inverter stage of uninterruptible power supplies (UPSs) is described, which is based on voltage and current predictive regulators.
Abstract: A digital control technique for the inverter stage of uninterruptible power supplies (UPSs) is described, which is based on voltage and current predictive regulators. Its aim is to achieve a deadbeat dynamic response for the controlled variables (output voltage and inverter current). The controller maintains the advantageous conventional multiloop structure and is capable of guaranteeing a high-quality dynamic performance. Moreover, its design is extremely simple and requires only a reasonably accurate knowledge of the output filter parameters. Finally, the only sensed variables are the output voltage and the converter output current. The validity of the proposed strategy is demonstrated by means of simulation and experimental results referring to a single-phase UPS laboratory prototype (1 kVA).

191 citations


Journal ArticleDOI
TL;DR: The authors obtain the power dynamics for both converter and inverter systems, and control the converter power so that it matches the required inverter power exactly, which helps them to circumvent a complex control method in regulating the DC-link voltage.
Abstract: The authors propose a new power converter control scheme for a converter-inverter system. The strategy is to fully utilize the inverter dynamics in controlling the converter dynamics. The authors obtain the power dynamics for both converter and inverter systems, and control the converter power so that it matches the required inverter power exactly. Then, in the ideal case, no power flows through the DC-link capacitors and, thus, the DC-link voltage does not fluctuate even though a very small amount of the DC-link capacitance is used. In forcing the converter power to match the inverter power, the authors utilize the master-slave control concept. They control the DC-link voltage level indirectly through the stored capacitor energy in order to exploit the advantage of the linear dynamic behavior of the capacitor energy. This helps them to circumvent a complex control method in regulating the DC-link voltage. Through simulation and experimental results, the superiority of the proposed converter control scheme is demonstrated.

Proceedings ArticleDOI
17 Jun 2001
TL;DR: In this article, different multicarrier PWM methods for a single phase five level cascaded inverter are investigated and analyzed with respect to resulting switching frequencies, complexity of implementation, spectrum of the output waveform, and the use of inverter state redundancies to perform additional application specific control tasks.
Abstract: This paper investigates and analyses different multicarrier PWM methods for a single phase five level cascaded inverter. Carrier disposition methods, phase shifted and a hybrid method are discussed with respect to resulting switching frequencies, complexity of implementation, spectrum of the output waveform, and the use of inverter state redundancies to perform additional application specific control tasks, such as power flow control from each DC source. A concept of separating the waveshaping function from the switch selection is explored and selected experimental results are presented.

Proceedings ArticleDOI
04 Mar 2001
TL;DR: A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point).
Abstract: A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point). A total of 64 voltage space vector combinations are available for PWM voltage control of the inverter fed machine with open-end winding. A space phasor based PWM scheme is proposed with minimum number of switching in a cycle per inverter coupled with equal number of switching for each inverter.

Journal ArticleDOI
TL;DR: In this article, a general ring oscillator topology for multiphase outputs is presented and analyzed, which uses the interpolating inverter stages to construct fast subfeedback loops for long chain rings to obtain both multi-phase outputs and higher speed operation.
Abstract: A general ring oscillator topology for multiphase outputs is presented and analyzed. The topology uses the interpolating inverter stages to construct fast subfeedback loops for long chain rings to obtain both multiphase outputs and higher speed operation. There exists an optimum number of inverter stages inside a subfeedback loop which gives the highest oscillation frequency. A fully integrated 1.25-GHz 0.35-/spl mu/m CMOS phase-locked-loop clock generator that incorporates the proposed voltage-controlled oscillator topology was designed and implemented for a data transceiver. It provides eight-phase outputs and achieves RMS tracking jitter of 11 ps from a 3.3-V power supply.

Journal ArticleDOI
TL;DR: A functional simulation model for the voltage-source inverter (VSI) using the switching function concept is studied and the actual implementation of the model is proposed with the help of Matlab Simulink.
Abstract: In this paper, a functional simulation model for the voltage-source inverter (VSI) using the switching function concept is studied and the actual implementation of the model is proposed with the help of Matlab Simulink. Also, this concept is extended to the voltage-doubler-type pulse width-modulated (PWM) AC-DC rectifier and the PWM AC-DC-AC converter. With the developed functional model, the simplification of the static power circuits can be achieved so that the convergence and long run-time problems can be solved. Also, in the functional model, the design parameters, such as voltage and current ratings of the power semiconductor switches and load current, can be easily calculated. The general switching function concept is reviewed in brief and the proposed functional models for the VSI, voltage-doubler rectifier, and PWM AC-DC-AC converter and their implementations using Matlab Simulink are explained in detail. Also, several informative simulation results verify the validity of the proposed models.

Journal ArticleDOI
TL;DR: In this article, a real-time space-vector-based control strategy for three-phase uninterruptible power supply systems powering nonlinear and unbalanced loads is presented.
Abstract: In this paper, a new real-time space-vector-based control strategy is presented for three-phase uninterruptible power supply systems powering nonlinear and unbalanced loads The proposed control strategy generates the inverter reference and gating signals in closed loop and guarantees high-quality output voltages at the load terminals The approach, which is implemented on a digital signal processor, adapts to a wide variation of nonlinear and unbalanced load conditions without specific knowledge of the output filter (L-C) component values Analysis and experimental results on a 10-kVA prototype are presented The results show that the output voltage is restored at heavy nonlinear and unbalanced load

Patent
09 Apr 2001
Abstract: A power control system for a turbogenerator which provides electrical power to one or more pump-jack oil wells. When the induction motor of a pump-jack oil well is powered by three-phase utility power, the speed of the pump-jack shaft varies only slightly over the pumping cycle but the utility power requirements can vary by four times the average pumping power. This power variation makes it impractical to power a pump-jack oil well with a stand-alone turbogenerator controlled by a conventional power control system. This power control system comprises a turbogenerator inverter, a load inverter, and a central processing unit which controls the frequency and voltage/current of each inverter. Throughout the oil well's pumping cycle, the central processing unit increases or decreases the frequency of the load inverter in order to axially accelerate and decelerate the masses of the down hole steel pump rods and oil, and to rotationally accelerate and decelerate the masses of the motor rotors and counter balance weights. This allows kinetic energy to be alternately stored in and extracted from the moving masses of the oil well and allows the oil pumping power to be precisely controlled. Historical data on the load inverter's frequency versus time profile throughout previous pumping cycles, which resulted in nearly constant turbogenerator power requirements, is utilized to further reduce variations in power.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a new scheme to attenuate the common mode noise and hence reduce shaft voltage in adjustable speed drive (ASD) driven motors, which is the most common modulation strategy adopted for motor control in ASDs.
Abstract: The most common modulation strategy adopted for motor control in adjustable speed drives (ASDs) is pulse width modulation (PWM). In general, the output is modulated at a carrier frequency ranging from 1.0 kHz to 20.0 kHz. Experiences with PWM drives have shown that there exist two important concerns: (1) common mode current; and (2) over-voltage at the motor when the distance between motor and the inverter is larger than the critical distance. The high carrier frequency along with fast rise and fall time of the insulated gate bipolar transistors (IGBTs) employed results in nontrivial common-mode or ground currents. The high dv/dt causes shaft voltage, which leads to bearing currents. This phenomenon has been identified as one of the reasons for premature bearing failure in PWM driven motors. A new scheme to attenuate the common mode noise and hence reduce shaft voltage is proposed. Experimental results showing the effectiveness of the proposed solution is also presented.

Patent
10 Aug 2001
TL;DR: In this paper, a unified constant-frequency integration (UCI) control method based on one-cycle control employs an integrator with reset as its core component along with a few logic and linear components to control the pulse width of a three-phase recitifier, active power filter, or grid-connected inverter.
Abstract: An unified constant-frequency integration (UCI) control method based on one-cycle control employs an integrator with reset as its core component along with a few logic and linear components to control the pulse width of a three-phase recitifier, active power filter, or grid-connected inverter so that the all three phase current draw from or the current output to the utility line is sinusoidal. No multipliers and reference calculation circuitry are needed for controlling active power filters. The UCI control employs constant switching frequency and operates in continuous conduction mode (CCM). If in some cases a DSP is desired for some other purposes, the Unified Constant-frequency Control function can be realized by a low cost DSP with a high reliability, because no high speed calcutation, high speed A/D converter, and mutipliers are required.

Journal ArticleDOI
TL;DR: The inverter switching frequency is predicted according to torque and flux hysteresis bands based on induction machine parameters and control sampling period, and the effect of hysteResis bands to line current harmonics is investigated.
Abstract: In this paper, the influences of the hysteresis bands on the direct torque control (DTC) of an induction motor are analytically investigated, and the switching frequency of the inverter is predicted based on the analysis. The flux and torque hysteresis bands are the only gains to be adjusted in DTC, and the inverter switching frequency and the current waveform are greatly influenced by them. Therefore, the magnitude of the hysteresis band should be determined based on reasonable guidelines which can avoid excessive inverter switching frequency and current harmonics in the whole operating region. This paper predicts the inverter switching frequency according to torque and flux hysteresis bands based on induction machine parameters and control sampling period, and investigates the effect of hysteresis bands to line current harmonics. The simulated and experimental results prove the usefulness and feasibility of the proposed method.

Patent
28 Mar 2001
TL;DR: In this article, the authors proposed a ground fault detection method for ground faults of a solar battery, where DC power input from the battery is converted into AC power and supplied to a system.
Abstract: The object is to reliably detect a ground fault of a solar battery. To detect a ground fault position to take an efficient measure against the ground fault, DC power input from a solar battery is converted into AC power and supplied to a system. In a system interconnection inverter (utility connected inverter) having non-insulated input and output, the input voltage of a converter circuit and/or the intermediate voltage between the converter circuit and an inverter circuit are varied to control the potential to ground at each portion of the solar battery to a value other than a value close to zero.

Journal ArticleDOI
TL;DR: A sensorless vector control system for general-purpose induction motors, which is based on the observer theory and the adaptive control theories, and an algorithm for compensating for the deadtime of the inverter and correcting the nonideal features of an insulated gate bipolar transistor was developed.
Abstract: This paper presents a sensorless vector control system for general-purpose induction motors, which is based on the observer theory and the adaptive control theories. The proposed system includes a rotor speed estimator using a q-axis flux and stator resistance identifier using the d-axis flux. The advantages of the proposed system are simplicity and avoidance of problems caused by using only a voltage model. Since the mathematical model of this system is constructed in a synchronously rotating reference frame, a linear model is easily derived for analyzing the system stability, including the influence of the observer gain, motor operating state, and parameter variations. In order to obtain stable low-speed operation and speed control accuracy, an algorithm for compensating for the deadtime of the inverter and correcting the nonideal features of an insulated gate bipolar transistor was developed. The effectiveness of the proposed system has been verified by digital simulation and experimentation.

Proceedings ArticleDOI
17 Jun 2001
TL;DR: In this paper, a simple and accurate method of computing conduction and switching loss is proposed for multi-level inverter system, which is proven for 3-level and 4-level diode clamped inverter systems.
Abstract: The multi-level inverter system is very promising in AC drives, when both reduced harmonic content and high power are required. But, as the output voltage level increase, the number of using the semiconductor device is increased. In case of multi-level inverter system, the loss of semiconductor devices cannot be analyzed by conventional methods. The reason is that the loss of each the semiconductor device is different from one another unlike 2-level and the diode clamped inverter system needs extra clamping diode. In this paper, a simple and accurate method of computing conduction and switching loss is proposed for multi-level inverter system. The validity of the proposed method is proven for 3-level and 4-level diode clamped inverter system.

Journal ArticleDOI
TL;DR: In this paper, a 4/spl times/4 decoupling transformation matrix is used that enables direct transformation between the four degree-of-freedom (DOF) leg-modulation space of the inverter and its corresponding 3-DOF output-voltage space.
Abstract: Four-leg (3-phase 4-wire) inverters are developed to power unbalanced/nonlinear three-phase loads. A unique 4/spl times/4 decoupling transformation matrix is used that enables direct transformation between the four degree-of-freedom (DOF) leg-modulation space of the inverter and its corresponding 3-DOF output-voltage space. This is analogous to the well-known 3/spl times/3 "abc-qd" transformation developed for the three-leg inverter. Details of this new 4/spl times/4 "Quad" transform are provided, along with a depiction of the voltage-vectors produced. Advanced synchronous-frame control techniques are applied with this 4-to-3 "abcn-qdo" transform to create a UPS-style inverter with sinewave output. Experimental results for an 8.6 kVA prototype inverter are presented.

Journal ArticleDOI
TL;DR: A direct torque control algorithm for three-level inverter-fed induction motors is presented and an adaptive observer is employed to bring better responses at the low-speed operation, by estimating some state variables and motor parameters which take a deep effect on the performance of theLow speed operation.
Abstract: A direct torque control algorithm for three-level inverter-fed induction motors is presented. Basic voltage selection methods similar to a two-level inverter provoke some problems such as stator-flux drooping phenomenon and undesirable torque control deterioration appeared, especially at low-speed operation. To overcome these problems, an algorithm with the basic switching sectors subdivided and intermediate voltage vectors applied is proposed in this paper. This algorithm basically considers applications in which direct torque-controlled induction motors are fed by three-level inverters with maximum switching frequency lowered around 1 kHz. An adaptive observer is also employed to bring better responses at the low-speed operation, by estimating some state variables and motor parameters which take a deep effect on the performance of the low-speed operation. Simulation and experiment results verify effectiveness of the proposed algorithm.

Journal ArticleDOI
01 Sep 2001
TL;DR: In this article, the performance of a self-excited induction generator (SEIG) under unbalanced and/or nonlinear loading conditions using a current-controlled voltage source inverter (CC-VSI) is analyzed.
Abstract: The analysed results of both voltage regulation and current-harmonic suppression of a self-excited induction generator (SEIG), under unbalanced and/or nonlinear loading conditions using a current-controlled voltage source inverter (CC-VSI) are presented. A hybrid induction-machine model based on the three-phase a-b-c and the d-q frames of reference is employed to describe the dynamic performance of the studied system. The three-phase a-b-c induction-machine model is employed to derive dynamic equations of the SEIG under nonlinear loading conditions. The synchronously rotating reference frame based on a d-q axis model is used to decompose three-phase load currents into active and reactive power currents. The three-phase a-b-c stator voltages of the SEIG and the DC bus voltage of the inverter are simultaneously controlled by a proportional-integral (PI) voltage controller and a harmonic compensator. The simulated results show that the performance of the SEIG under unbalanced and/or nonlinear loading conditions has been effectively improved by the proposed compensating scheme.

Patent
06 Apr 2001
TL;DR: In this article, a method and apparatus for providing a welding current is described, where the power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal.
Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.

Patent
05 Dec 2001
TL;DR: An electronic ballast for driving at least one gas discharge lamp from a source of AC power which has a substantially sinusoidal line voltage at a given line frequency is presented in this paper.
Abstract: An electronic ballast for driving at least one gas discharge lamp from a source of AC power which has a substantially sinusoidal line voltage at a given line frequency. The ballast includes a rectifying circuit having AC input terminals and DC output terminals, the AC input terminals connectable to the source of AC power, the rectifying circuit producing a rectified output voltage at its the DC output terminals when the AC input terminals are energized by the source of AC power; a valley fill circuit having input and output terminals; the input terminals of the valley fill circuit connected to the DC output terminals of the rectifying circuit; an inverter circuit having input terminals and output terminals; the input terminals of the inverter circuit connected to the output terminals of the valley fill circuit and the output terminals of the inverter circuit connectable to the at least one gas discharge lamp and producing a high frequency drive voltage for driving a lamp current through the at least one gas discharge lamp when the AC input terminals are energized by the source of AC power. The inverter circuit has a single controllably conductive device and an inductor; the inductor connectable to the at least one gas discharge lamp; the inverter circuit being adapted to draw current from the source of AC power whereby the total current drawn from the source of AC power has a total harmonic distortion below about 33.3%; and whereby the lamp current has a current crest factor below about 2.1.

01 Jan 2001
TL;DR: In this article, a unique 4 4 de- coupling transformation matrix is used that enables direct trans-formation between the four degree-of-freedom (DOF) leg-modu- lation space of the inverter and its corresponding 3-DOF output voltage space.
Abstract: Four-Leg (3-phase 4-wire) inverters are developed to power unbalanced/nonlinear three-phase loads. A unique 4 4 de- coupling transformation matrix is used that enables direct trans- formation between the four degree-of-freedom (DOF) leg-modu- lation space of the inverter and its corresponding 3-DOF output- voltage space. This is analogous to the well-known 3 3" - " transformation developed for the three-leg inverter. Details of this new 4 4 "Quad" transform are provided, along with a de- piction of the voltage-vectors produced. Advanced synchronous- frame control techniques are applied with this 4-to-3 " - " transform to create a UPS-style inverter with sinewave output. Ex- perimental results for an 8.6 kVA prototype inverter are presented.

Journal ArticleDOI
01 Sep 2001
TL;DR: In this paper, the authors discuss the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high quality power.
Abstract: The paper discusses the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid. A variable-speed wind power conversion system is used for illustration, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high-quality power. The power control principles of VSI are described. Various system configurations and switching strategies are examined by analysis, simulation and experimental methods. It is shown that better utilisation of semiconductors and more flexible control may be achieved by using a separately controlled DC link, rather than a directly connected VSI that has to operate at a lower modulation ratio at higher power. In some cases, multipulse inverter structures may be preferred, despite higher component count, because of reduced switching losses, fault tolerance and the absence of filters. The solutions developed in the study could be applied at a different scale to other renewable energy sources, such as wave or solar photovoltaic devices.