Showing papers on "Total harmonic distortion published in 1995"
Book•
01 Oct 1995
TL;DR: In this paper, the authors present a power quality evaluation procedure for the purpose of measuring the power quality of a power supply. But, they do not define the specific classes of power quality problems.
Abstract: CHAPTER 1: INTRODUCTION What is Power Quality? Power Quality -- Voltage Quality Why Are We Concerned About Power Quality? The Power Quality Evaluation Procedure Who Should Use This Book Overview of the Contents CHAPTER 2: TERMS AND DEFINITIONS Need for a Consistent Vocabulary General Classes of Power Quality Problems Transients Long-Duration Voltage Variations Short-Duration Voltage Variations Voltage Imbalance Waveform Distortion Voltage Fluctuation Power Frequency Variations Power Quality Terms Ambiguous Terms CBEMA and ITI Curves References CHAPTER 3: VOLTAGE SAGS AND INTERRUPTIONS Sources of Sags and Interruptions Estimating Voltage Sag Performance Fundamental Principles of Protection Solutions at the End-User Level Evaluating the Economics of Different Ride-Through Alternatives Motor-Starting Sags Utility System Fault-Clearing Issues References CHAPTER 4: TRANSIENT OVERVOLTAGES Sources of Transient Overvoltages Principles of Overvoltage Protection Devices for Overvoltage Protection Utility Capacitor-Switching Transients Utility System Lightning Protection Managing Ferroresonance Switching Transient Problems with Loads Computer Tools for Transients Analysis References CHAPTER 5: FUNDAMENTALS OF HARMONICS Harmonic Distortion Voltage versus Current Distortion Harmonics versus Transients Harmonic Indexes Harmonic Sources from Commercial Loads Harmonic Sources from Industrial Loads Locating Harmonic Sources System Response Characteristics Effects of Harmonic Distortion Interharmonics References Bibliography CHAPTER 6: APPLIED HARMONICS Harmonic Distortion Evaluations Principles for Controlling Harmonics Where to Control Harmonics Harmonic Studies Devices for Controlling Harmonic Distortion Harmonic Filter Design: A Case Study Case Studies Standards of Harmonics References Bibliography CHAPTER 7: LONG-DURATION VOLTAGE VARIATIONS Principles of Regulating the Voltage Devices for Voltage Regulation Utility Voltage Regulator Application Capacitors for Voltage Regulation End-User Capacitor Application Regulating Utility Voltage with Distributed Resources Flicker References Bibliography CHAPTER 8: POWER QUALITY BENCHMARKING Introduction Benchmarking Process RMS Voltage Variation Indices Harmonics Indices Power Quality Contracts Power Quality Insurance Power Quality State Estimation Including Power Quality in Distribution Planning References Bibliography CHAPTER 9: DISTRIBUTED GENERATION AND POWER QUALITY Resurgence of DG DG Technologies Interface to the Utility System Power Quality Issues Operating Conflicts DG on Distribution Networks Siting DGDistributed Generation Interconnection Standards Summary References Bibliography CHAPTER 10: WIRING AND GROUNDING Resources Definitions Reasons for Grounding Typical Wiring and Grounding Problems Solutions to Wiring and Grounding Problems Bibliography CHAPTER 11: POWER QUALITY MONITORING Monitoring Considerations Historical Perspective of Power Quality Measuring Instruments Power Quality Measurement Equipment Assessment of Power Quality Measurement Data Application of Intelligent Systems Power Quality Monitoring Standards References Index INDEX
1,991 citations
TL;DR: In this paper, a power line conditioner consisting of two small rating series active filters and a shunt passive filter is proposed to reduce voltage distortion at the connection point, and eliminate harmonic currents escaping into the system upstream of the connection points.
Abstract: This paper proposes a new power line conditioner consisting of two small rating series active filters and a shunt passive filter. The power line conditioner aims at a general filtering system which will be installed at the point of common coupling in a power system feeding harmonic-sensitive loads and unidentified harmonic-producing loads. One of the two active filters is connected in series with the supply, while another is in series with the shunt passive filter. The purpose of the power line conditioner is to reduce voltage distortion at the connection point, and is to eliminate harmonic currents escaping into the system upstream of the connection point. A control scheme of the two series active filters which play an important role is described in this paper. Its filtering characteristics are discussed with the focus on voltage and current distortion. A prototype model of 20 kVA is constructed to verify the functionality and performance of the power line conditioner. >
209 citations
18 Jun 1995
TL;DR: In this paper, a polyphase transformer arrangement with reduced kVA capacities is presented for harmonic current reduction in high power rectifier utility interface systems, where rectifier diodes each conduct for 120 degrees per cycle and the fifth and seventh harmonics are absent from the utility input line current.
Abstract: In this paper, polyphase transformer arrangements with reduced kVA capacities are presented for harmonic current reduction in high power rectifier utility interface systems. Based on the concept of an autotransformer, a proposed twelve-pulse rectifier system is realized with a resultant kVA rating of 0.18P/sub 0/ (pu). In this arrangement, the rectifier diodes each conduct for 120 degrees per cycle and the fifth and seventh harmonics are absent from the utility input line current. In the second scheme, an eighteen-pulse rectifier is realized with a kVA rating of 0.16P/sub 0/ (pu), rectifier diode conduction of 120 degrees per cycle and fifth, seventh, eleventh and thirteenth harmonic cancellation in the utility line currents. Additional applications for the proposed polyphase transformer arrangements include twelve and eighteen-pulse systems feeding multiple six-pulse nonlinear loads, such as AC motor drives, with an appropriate phase shift, and this arrangement substantially reduces the utility line current harmonics. For example, it is shown that the fifth and seventh harmonics generated by two separate six-pulse nonlinear loads are subtracted and this contributes to reduced harmonic distortion. Simulation results verifying the proposed concept are presented. >
209 citations
TL;DR: This method is useful for shunt active power filters and is capable to eliminate harmonics, compensate power factor, and correct unbalance problems simultaneously, and has the ability to slow-down sudden transient changes in the load.
Abstract: The effectiveness of an active power filter depends basically on three characteristics: (a) the modulation method used; (b) the design characteristics of the PWM modulator; and (c) the method implemented to generate the reference template. For the last characteristic there are many methods, most of them complicated and hence difficult to implement and adjust. In this paper, a new method, which has simplicity at its main characteristic, is presented. The method is based on "sample and hold" circuits, synchronized with the peak value of the phase-to-neutral mains voltage. This method is useful for shunt active power filters and is capable to eliminate harmonics, compensate power factor, and correct unbalance problems simultaneously. It also has the ability to slow-down sudden transient changes in the load. Experimental results, with the reference template obtained with the method, are presented in the paper.
197 citations
TL;DR: In this paper, a simple fiber-optic link with a representative set of link parameters and a variety of electrooptic modulators: simple Mach-Zehnder, linearized dual and triple MZHnder, simple directional coupler (two operating points), and linearized directional coupling with one and two dc electrodes are compared.
Abstract: Intermodulation and harmonic distortion are calculated for a simple fiber-optic link with a representative set of link parameters and a variety of electrooptic modulators: simple Mach-Zehnder, linearized dual and triple Mach-Zehnder, simple directional coupler (two operating points), and linearized directional coupler with one and two dc electrodes. The resulting dynamic ranges, gains, and noise figures are compared for these modulators. A new definition of dynamic range is proposed to accommodate the more complicated variation of intermodulation with input power exhibited by linearized modulators. The effects of noise bandwidth, preamplifier distortion, and errors in modulator operating conditions are described. >
170 citations
TL;DR: In this paper, the results of simulations were used to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building.
Abstract: In this paper we use the results of simulations to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building. We take into account attenuation due to system impedance and voltage distortion, as well as diversity in harmonic current phase angles due to variations in power and circuit parameters. Using experimental and published data we establish ranges of circuit parameters for an equivalent 120 V, 100 W "base computer unit" and branch circuit, update our computer modeling code (described in previous papers) to iteratively handle the interaction between current and voltage harmonics, and use the code to predict the net harmonic injection currents at the point of common coupling (PCC) represented by a shared transformer connected to a stiff power system. The key contributions of this paper are: providing estimates of the net harmonic current injection due to distributed single-phase computer loads in Amps/kW, as well as in percent of fundamental current, for a wide range of system loading and voltage distortion conditions; and illustrating that the reduction in harmonic currents due to phase angle diversity (expressed in Amps/kW) is relatively independent of system loading, whereas the reduction due to attenuation increases significantly with system loading. >
163 citations
TL;DR: In this paper, the interactions between the incremental changes of current harmonic phasors injected by a power system NL (nonlinear load) and the resulting variations of harmonic voltages and powers are analyzed.
Abstract: This paper analyses the interactions between the incremental changes of current harmonic phasors injected by a power system NL (nonlinear load) and the resulting variations of harmonic voltages and powers. It proves that it is not always possible, following simple measurements of individual harmonic powers, to decide if a certain harmonic current is harmful or useful. It is suggested that the NL "distortion" be evaluated with the help of a quantity called non60 Hz (nonfundamental) apparent power. >
161 citations
Proceedings Article•
01 Sep 1995TL;DR: In this article, the authors describe the principle and design of a CMOS variable-gain amplifier for high-frequency applications, which is based on a linear voltage-to-current conversion by means of a digitally controlled conversion impedance.
Abstract: This paper describes the principle and design of a CMOS variable-gain amplifier for high-frequency applications. The operation of the differential circuit is based on a linear voltage-to-current conversion by means of a digitally controlled conversion impedance. Experimental results of the circuit show total harmonic distortion figures better than ?60 dB and a gain accuracy of 0.05 dB over the ?2 to + 12 dB gain range.
153 citations
TL;DR: In this paper, the effect of supply voltage harmonics on the response of single-phase capacitor-filtered diode bridge rectifier loads was investigated, and a complete analytical model for calculating the current harmonics of these loads, when energized by nonsinusoidal supply voltages, was presented.
Abstract: This paper describes the effect of supply voltage harmonics on the response of single-phase capacitor-filtered diode bridge rectifier loads. A complete analytical model for calculating the current harmonics of these loads, when energized by nonsinusoidal supply voltages, is presented. The model is then used to investigate the effect of supply voltage harmonics on current harmonics. The key findings of the paper are as follows: (1) the phase angles of supply voltage harmonics determine whether or not these harmonics increase or decrease current distortion. In general, a peaked voltage wave increases input current distortion, whereas a flattened wave has the opposite effect. Because of this complex relationship, voltage crest factor is a much better predictor of total harmonic current distortion than is total harmonic voltage distortion. (2) The current harmonics created by these loads produce voltage harmonics that tend to have a partial self-compensating effect on the current harmonics. >
148 citations
05 Mar 1995
TL;DR: A survey of PWM boost rectifier circuit topologies for controlling a nonisolated DC-rail voltage whilst drawing supply currents at a unity fundamental power factor and with a low total harmonic distortion is provided in this paper.
Abstract: This paper provides a survey of PWM boost rectifier circuit topologies for controlling a nonisolated DC-rail voltage whilst drawing supply currents at a unity fundamental power factor and with a low total harmonic distortion. Rectifier-leg topologies are classified by the number of switches and by the PWM waveforms generated. Complete rectifier circuit topologies are described for operation off 1-phase and 3-phase AC supplies. Circuit analogies are made between rectifiers for 1 and 3 phases, rectifiers using either a single or a split DC-rail and between rectifiers using either AC or DC side inductors. The performances of the various circuits are assessed with reference to factors such as conduction losses, efficiency, switch count, semiconductor voltage stresses, 3-level and 2-level PWM voltage waveforms and, finally, bi-directional power conversion. >
144 citations
08 Oct 1995
TL;DR: A simple, self adjusting analog prediction of the hysteresis band is added to the phase-locked-loop control to ensure constant switching frequency even at high rate of output voltage change, such as required in active filters, fast drives and in other high demanding applications.
Abstract: An improved implementation of the constant-frequency hysteresis current control of three-phase voltage-source inverters is presented A simple, self-adjusting analog prediction of the hysteresis band is added to the phase-locked-loop control to ensure constant switching frequency, even at a high rate of output voltage change, such as required in active filters, fast drives and other highly demanding applications This provision also improves the relative position of phase modulation pulses, thus reducing the current ripple The prediction method is robust and uses a small number of inexpensive components It does not require trimming or tuning, giving the whole system the capability to adjust itself to different load conditions Thus, the control becomes suitable for hybrid or monolithic integration In this paper, the basic principles are described, and a detailed stability analysis is carried out The control performance is illustrated, both by simulated and experimental results
TL;DR: In this article, a method of robust (insensitive to system parameter variations and load current changes) and fast digital control for an uninterruptible power supply (UPS) with a three-phase PWM inverter is described.
Abstract: This paper describes a novel method of robust (insensitive to system parameter variations and load current changes) and fast digital control for an uninterruptible power supply (UPS) with a three-phase PWM inverter. The purpose of this paper is to propose a method by which characteristics better than those by conventional methods are obtained using an algorithm simpler than that of conventional methods. The experiments show that the purpose is achieved and the proposed method offers a total harmonic distortion of 0.6% of the output voltage waveform at a full nonlinear load. The analysis shows that the stability of the method is sufficient. Three features of the method are: (a) a capacitor current observer for stabilization and a disturbance observer for robustness are used to compensate the time lag by the computation and the disturbances, in a minor loop of the capacitor current through an inductor-capacitor filter of the inverter; (b) new models of the inverter and the disturbances are established to simplify these observers; and (c) the output voltage control loop can be designed easily and exactly because the minor loop realizes a rapid and robust control of the current. >
18 Jun 1995
TL;DR: In this article, the output voltage control is structured around an inner filter capacitor current loop where capacitor current is sensed via a single, small current transformer, which avoids the expense of multiple, active current sensors.
Abstract: This paper presents a state space approach to the problem of controlling a single phase PWM inverter with an LC output filter. These types of inverter are often used in uninterruptable power supplies (UPS) where a sine wave output voltage is to be maintained. Output voltage control is structured around an inner filter capacitor current loop where capacitor current is sensed via a single, small current transformer. This avoids the expense of multiple, active current sensors found in alternative designs. Performance of the capacitor current loop is enhanced with active decoupling of both the DC bus and the equivalent "back-EMF" of the output voltage. The output dynamic stiffness of the system is analyzed and plotted. Experimental results yield less than 0.5% total harmonic distortion (THD) at full load (8 kW), with transient response times of less than 200 /spl mu/s. >
Patent•
16 May 1995TL;DR: In this article, a photovoltaic (PV) power system having distributed square wave current DC to AC inverters integral with strings of PV cells in a PV array is arranged into four quadrants and phase-shifted and summed AC voltages from each quadrant are further summed in a 12-phase to 3-phase transformer to produce a sinusoidal 3phase AC voltage with a total harmonic distortion of less than 5 percent.
Abstract: A photovoltaic (PV) power system having distributed square wave current DC to AC inverters integral with strings of PV cells in a PV array. The PV array is arranged into four quadrants and phase-shifted and summed AC voltages from each quadrant are further summed in a 12-phase to 3-phase transformer to produce a sinusoidal 3-phase AC voltage with a total harmonic distortion of less than 5 percent.
TL;DR: In this article, a second-order sigma-delta modulator with a 3-b internal quantizer employing the individual level averaging technique has been designed and implemented in a 1.2 /spl mu/m CMOS technology.
Abstract: A second-order sigma-delta modulator with a 3-b internal quantizer employing the individual level averaging technique has been designed and implemented in a 1.2 /spl mu/m CMOS technology. Testing results show no observable harmonic distortion components above the noise floor. Peak S/(N+D) ratio of 91 dB and dynamic range of 96 dB have been achieved at a clock rate of 2.56 MHz for a 20 kHz baseband. No tone is observed in the baseband as the amplitude of a 10 kHz input sine wave is reduced from -0.5 dB to -107 dB below the voltage reference. The active area of the prototype chip is 3.1 mm/sup 2/ and it dissipates 67.5 mW of power from a 5 V supply. >
TL;DR: Carrier subtraction from a weakly modulated optical signal is proposed, analyzed, and demonstrated in this paper to improve fiber-optic system efficiency, achieving an improvement of 9-13 dB in link loss from 1 to 25 GHz.
Abstract: Carrier subtraction from a weakly modulated optical signal is proposed, analyzed, and demonstrated to improve fiber-optic system efficiency. For constant photodetector current, an amount of carrier suppression results in an equal amount of RF gain. Improvement of 9-13 dB in link loss from 1 to 25 GHz is measured using a Fabry-Perot filter operating in the reflection mode. Measured induced harmonic distortion agrees with predicted values. >
01 Jun 1995
TL;DR: In this paper, the authors proposed a method based on the evaluation of the harmonic powers to identify whether the source producing harmonic distortion in the line currents and voltages of a three-phase system is a polluting load connected after the metering section or is the distortion of the line voltages.
Abstract: The number and power of loads that pollute, from an electric point of view, the electric network are constantly increasing. Their connection to the electric network causes a significant distortion in the line current and, when their overall power is no longer negligible with respect to the network power, also some distortion in the line voltage, thus deteriorating the electric supply quality. The paper proposes a method, based on the evaluation of the harmonic powers, to identify whether the source producing harmonic distortion in the line currents and voltages of a three-phase system is a polluting load connected after the metering section or is the distortion of the line voltages. Some parameters are also defined in order to quantify the effects of the polluting load on the power quality. A Virtual Instrument is also described, realized to implement the proposed method and to verify it experimentally. The instrument accuracy is discussed. >
TL;DR: In this paper, the authors proposed a new method of harmonic power detection based on the instantaneous active power in three-phase circuits, and its applications to search for dominant harmonic sources in power systems.
Abstract: This paper presents a new method of harmonic power detection based on the instantaneous active power in three-phase circuits, and its applications to search for dominant harmonic sources in power systems. The proposed method requires only band elimination filters and a three-phase active power meter to detect the harmonic active power, and it is able to deal with harmonic power flow more easily and precisely than a conventional meter which is based on Fourier series of single-phase circuits. In addition, measurement errors of the harmonic power are discussed theoretically. The validity of the proposed method is demonstrated by digital simulation. >
TL;DR: In this paper, the authors used a combination of EMTP simulations and conventional harmonic analysis simulations to predict the distribution system distortion levels as a function of system characteristics, the CFL characteristics, and the CFL penetration level.
Abstract: Compact fluorescent lamps (CFLs) have the potential to increase the overall harmonic distortion levels on distribution systems. Measurements of the harmonic characteristics of different types of CFLs are presented and the possible impacts on a distribution system are analyzed. The analysis uses a combination of EMTP simulations and conventional harmonic analysis simulations to predict the distribution system distortion levels as a function of system characteristics, the CFL characteristics, and the CFL penetration level.
TL;DR: In this article, a three-phase, single-stage, isolated PWM rectifier is proposed, which is capable of achieving unity power factor and low harmonic distortion of input currents, and at the same time realizing zero-voltage switching for all power semiconductor devices.
Abstract: A novel three-phase, single-stage, isolated PWM rectifier is proposed, which is capable of achieving unity power factor, and low harmonic distortion of input currents, and at the same time realizing zero-voltage switching for all power semiconductor devices. Operation of the proposed circuit is thoroughly analyzed. Design equations and trade-offs are provided. The performance of the proposed circuit is demonstrated through a 2 kW, 100 kHz, digital signal processor controlled prototype. The conversion efficiency is around 93%. >
TL;DR: In this article, generalized techniques for realizing PWM patterns which provide selective harmonic elimination and current magnitude modulation (SHEM) for current source inverters/power converters (CSI/C).
Abstract: This paper presents generalized techniques for realizing PWM patterns which provide selective harmonic elimination and current magnitude modulation (SHEM) for current source inverters/power converters (CSI/C). A combination of chops and short circuit pulses are positioned in such a way that lower order harmonics are eliminated selectively besides current magnitude modulation with minimum switching frequency. Generalized equations and tables which show the relationship of various PWM-SHEM parameters to the position of short circuit pulses and the number of chops per 30/spl deg/ are provided and discussed in detail. >
08 Oct 1995
TL;DR: In this article, an active damping function can be realized by feedback control of an LC filter connected to the AC side of the rectifier, which does not require any additional components in the main circuits, permitting a simple circuit configuration.
Abstract: A new control method for current-type pulse-width modulation (PWM) rectifiers which can provide active damping function is presented. This damping function is effective only on the harmonic components of AC input current selectively. Thus steady-state waveform distortion and transient oscillation of the input current are reduced by the active damping effects. The active damping function can be realized by feedback control of an LC filter connected to the AC side of the rectifier, and it does not require any additional components in the main circuits, permitting a simple circuit configuration. The control system of the proposed PWM rectifier is analyzed by using a simple block diagram developed in the present paper. From the analytical results, the influence of the circuit parameters and control delay on the active damping effects and the stability of the operation are clarified to establish the design method. To confirm the effectiveness of the active damping function, some results of basic experiments are included. As an example of application of the active damping function, the proposed rectifier is applied to reduce the harmonic currents generated by conventional rectifiers operating in parallel with the proposed rectifier. Some experimental results in this application are also included.
18 Jun 1995
TL;DR: In this article, an improved control strategy of standard power factor preregulators (PFPs) is proposed which allows fast output voltage response while maintaining a high power factor, which is obtained by compensating for the intrinsic low-frequency output voltage ripple, thus allowing a higher bandwidth of the output voltage control loop.
Abstract: An improved control strategy of standard power factor preregulators (PFPs) is proposed which allows fast output voltage response while maintaining a high power factor. This is obtained by compensating for the intrinsic low-frequency output voltage ripple, thus allowing a higher bandwidth of the output voltage control loop. This method does not require additional sensing, but only a multiplier and simple analog circuitry, and works well with a universal input voltage range. Experimental tests on a boost power converter with average current control confirm the validity of the approach.
TL;DR: In this article, a second-order low-pass continuous-time filter operating at a 3 V power supply is presented, where the output common mode voltage is controlled at the filter level using lossy integrators.
Abstract: The reduction of the supply voltage forces one to develop system and circuit solutions able to achieve the same performance previously obtained with higher supply voltage. In this paper, a second-order low-pass continuous-time filter operating at a 3 V power supply is presented. The prototype filter is implemented using a highly linear pseudo-differential transconductor. The input common-mode signal is canceled at the transconductor level using a feed-forward path. The output common mode voltage is controlled at the filter level using lossy integrators. A prototype cell has been realized in 1.2 /spl mu/m BiCMOS technology. The pole frequency can be tuned in the range 12-55 MHz. A THD of -40 dB is achieved for signals up to 1 V/sub pp/ at 10 MHz. The dynamic range is approximately 60 dB.
06 Nov 1995
TL;DR: In this paper, a static power convertor active power filter based on a DSP controller with enhanced performance of current control is presented, where a novel predictive current control method is introduced to compensate the phase error of harmonic components due to discrete sampling.
Abstract: This paper presents a static power convertor active power filter based on a DSP controller with enhanced performance of current control. A novel predictive current control method is introduced to compensate the phase error of harmonic components due to discrete sampling. With a close coordination between the reference current prediction, PWM pattern generation, and control timing, high performance control is achieved. Experimental results show that the developed system gives satisfactory performances in its harmonic/reactive power compensation.
TL;DR: A new approach using fuzzy dynamic programming to decide the optimal location and size of compensation shunt capacitors for distribution systems with harmonic distortion and it is found that the system loss and harmonic distortion can be reduced very effectively by this proposed algorithm.
01 Feb 1995
TL;DR: In this article, a multiphase sinusoidal oscillator using the parasitic poles of current feedback operational amplifiers (CFOAs) is presented, which can generate n signals which are equal in amplitude and equally spaced in phase.
Abstract: A multiphase sinusoidal oscillator using the parasitic poles of current feedback operational amplifiers (CFOAs) is presented. The oscillator can generate n signals which are equal in amplitude and equally spaced in phase. The oscillator using the parasitic poles of CFOAs is suitable for high frequency applications and monolithic IC fabrication. The effects caused by the nonlinearity of the CFOA on the oscillation frequency and condition have been analysed. Experimental results show that a three-phase sinusoidal oscillator has a wide operating range from 10 kHz to 10 MHz and a large output voltage swing up to 7 V peak to peak while using +or-5 V power supply. The total harmonic distortion (THD) of each oscillation frequency is dominated by its third harmonic component which is at least 33 dB down from its fundamental.
06 Nov 1995
TL;DR: In this article, the authors propose a state variable control technique that introduces more flexibility in the control of the rectifier and a more straightforward approach to controller design, which consists in linearizing the state variable model of the system in the dq frame, decoupling and independently controlling the two components of the line current (active and reactive), eliminating the input damping resistors, and rejecting the effect of supply voltage variations.
Abstract: Current source PWM rectifiers among others are gradually replacing thyristor line commutated rectifiers as a source of variable DC power. Advantages include reduced line current harmonic distortion and complete power factor control, including unity power factor operation. However, due to intrinsic nonlinearities and stability problems, the control of the rectifier has usually been achieved using off-line patterns or direct line current control in the abc frame. This paper proposes a state variable control technique that introduces more flexibility in the control of the rectifier and a more straightforward approach to controller design. The proposed technique consists in linearizing the state variable model of the system in the dq frame, decoupling and independently controlling the two components of the line current (active and reactive), eliminating the input damping resistors, and rejecting the effect of supply voltage variations. Also, a space vector modulation technique is used to maximize the current gain and switch utilization of the rectifier. The paper includes a complete formulation of the equations of the decoupled system and a controller design procedure. Experimental results on a 2 kVA DSP based prototype confirm the theoretical considerations.
TL;DR: This paper presents the first rigorous and quantitative theoretical analysis of the conversion error introduced by an important type of D/A converter with dynamic element matching and provides an expression for the power of the white noise in terms of thePower of the input sequence and the component matching errors.
Abstract: A known approach to reducing harmonic distortion in D/A converters involves a technique called dynamic element matching, The idea is not to reduce the power of the overall conversion error but rather to give it a random, noise-like structure. By reducing the correlation among successive samples of the conversion error, harmonic distortion is reduced. This paper presents the first rigorous and quantitative theoretical analysis of the conversion error introduced by an important type of D/A converter with dynamic element matching, In addition to supporting previously published experimental results that indicate the conversion error consists of white noise instead of harmonic distortion, the analysis provides an expression for the power of the white noise in terms of the power of the input sequence and the component matching errors. A yield estimation technique based on the expression is presented that can be used to estimate how the power of the white noise varies across different copies of the same D/A converter circuit for any given component matching error statistics.
TL;DR: In this article, the bias dependence of the power output spectrum and the generation of intermodulation products from different HEMT's and MESFET's at large signal excitation is studied and compared with simulated values.
Abstract: The bias dependence of the power output spectrum and the generation of intermodulation products from different HEMT's and MESFET's at large signal excitation is studied and compared with simulated values. An extended HEMT/FET model suitable for small and and negative V/sub ds/ (with a drain voltage dependence of the peak transconductance in the unsaturated drain current region, and at negative drain voltage), is also proposed. Good agreement between simulated and measured power spectrum up to at least the fourth harmonic is demonstrated for HEMT and MESFET devices from different manufacturers. Measured and simulated intermodulation products are also in good agreement, which confirm the validity of the model. >