Showing papers on "Total harmonic distortion published in 1989"

Update of harmonic standard IEEE-519: IEEE Recommended Practices and Requirements for Harmonic Control in Electric Power Systems

Abstract: The authors present the changes in IEEE STD 519-1981, titled IEEE Guide for Harmonic Control and Reactive Compensation of Static Power Converters, that are to be made in 1988 as the result of a two-year review. The voltage distortion criteria in the 1981 edition could not be used to distribute among users, the ability of the utility system to absorb harmonic currents. This problem is addressed in the revision. There are now two criteria that are used to evaluate harmonic distortion. The first is a limitation in the harmonic current that a user can transmit into the utility system. The second criterion is the quality of the voltage that the utility must furnish the user. Examples of the application of the revised standard, which has been upgraded to a Recommended Practice, are given. >

A noise-shaping coder topology for 15+ bit converters

Abstract: A topology for high-precision noise-shaping converters that can be integrated on a standard digital IC process is presented. This topology uses a multibit noise-shaping coder and a novel form of dynamic element matching to achieve high accuracy and long-term stability without requiring precision matching of components. A fourth-order noise-shaping D/A (digital-to-analog) conversion system using a 3-b quantizer and a dynamic element-matching internal D/A converter, fabricated in a standard double-metal 3- mu m CMOS process, achieved 16-bit dynamic range and a harmonic distortion below -90 dB. This multibit noise-shaping D/A conversion system achieved performance comparable to that of a 1-bit noise-shaping D/A conversion system that operated at nearly four times its clock rate. >

A self-calibration technique for monolithic high-resolution D/A converters

Abstract: A self-calibration technique based upon charge storage on the gate-source capacitance of CMOS transistors is presented. The technique can produce multiple copies of a reference current. Therefore, it is suitable for the calibration of high-resolution D/A (digital/analog) converters which are based upon equal current sources. As the storage capacitor is internal, no external components are required. A calibrated spare current source is used to allow continuous converter operation. This implies that no special calibration cycles are required. To show the capabilities of the calibration technique, it was implemented in a 16-b D/A converter. Measurement results show a total harmonic distortion of 0.0025% at a power consumption of 20 mW and a minimum supply voltage of 3 V. The design was fabricated in a 1.6- mu m double-metal CMOS process without special options. >

A 14-bit 80-kHz sigma-delta A/D converter: modeling, design and performance evaluation

Abstract: The development is described of a sigma-delta A/D (analog-to-digital) converter Included is a brief overview of sigma-delta conversion The A/D converter achieves an 885-dB dynamic range and a maximum signal-to-noise ratio of 815 dB The harmonic distortion is negligible This level of performance is about 10 dB higher than previously reported results for oversampled A/D converters in this frequency range The analog modulator uses a double-integration switched-capacitor architecture with an oversampling rate of 1024 MHz Transconductance amplifiers having a 160-MHz f/sub t/ were developed for the integrators The circuit is implemented in a 175- mu m 5-V CMOS process The analog circuitry occupies 2 mm/sup 2/ of silicon area and consumes 75 mW of power Some of the difficult problems associated with evaluating the performance of sigma-delta converters are described The design of a sigma-delta development and performance evaluation system is presented This system includes a custom interface board linking the chip to a Sun workstation, and extensive digital signal processing and analysis software >

A 17 bit oversampling D-A conversion technology using multistage noise shaping

Abstract: A description is given of a highly stable, triple-integration two-stage noise-shaping technique and a precise differential pulse-width modulation (PWM) output method which permits greater accuracy in monolithic audio digital-to-analog (D-to-A) converters (DACs) without trimming. Based on these techniques and using 1.5 mu m CMOS technology, a 17 bit 20 kHz bandwidth DAC LSI chip with digital filters was developed. A signal-to-noise ratio (S/(N+THD)) of 101 dB and a total harmonic distortion (THD) of 0.0007% at full-scale input were obtained. >

A line voltage regulator/conditioner for harmonic-sensitive load isolation

Abstract: A technique is presented for the isolation of harmonic-sensitive loads from harmonic-producing loads, such as rectifiers and power converters. The solution, referred to as a line voltage regulator/conditioner (LVRC), utilizes a combination of a series and a parallel active power filter. The series filter isolates the sensitive loads on the output side of the LVRC from the nonlinear, distortion-producing loads on the input side by correcting for the harmonic voltage distortion present at the input. In addition, the series filter is utilized to regulate the output voltage. The parallel filter acts to generate the harmonic current required by the loads connected on the output side, therefore reflecting a linear load to the source. >

AC to DC power conversion circuit with low harmonic distortion

Abstract: In an AC to DC power conversion circuit including a boost inductor connected in series between a full-wave rectifier and a DC load, a switch is connected to selectively shunt boost inductor current from the load. Switch conduction is controlled by a pulse width modulator generating switching pulses at a high fixed frequency. The pulse widths are automatically varied as a function of boost inductor current, load voltage, and an ideal sinusoidal waveform derived from the AC input voltage to force the boost inductor current to closely conform to the ideal sinusoidal waveform and thus minimize harmonic distortion, while achieving load voltage regulation and near unity power factor.

Optimal power control strategies for neutral point clamped (NPC) inverter topology

Abstract: A programmed pulsewidth modulation (PWM) technique for selectively eliminating several lower-order harmonics at the output of a neutral point clamped (NPC) inverter topology is investigated. The switching function approach is utilized to derive relevant analytical expressions for input/output variables. A thorough evaluation of the NPC inverter topology based on the switching function approach is described. Optimal power control strategies for an NPC inverter employing programmed PWM patterns are proposed. For a constant-frequency variable-voltage NPC inverter power supply, the proposed strategy is to maintain a minimum specified total harmonic distortion employing a low-output impedance filter. In the case of an NPC inverter powering an AC motor drive, the proposed strategy is to maintain a minimum specified harmonic current factor. The proposed power control strategies are achieved without substantial increase in inverter switching frequency and are therefore suitable for high-power applications employing gate-turn-off-thyristor (GTO) type devices. >

Survey of harmonic levels on the American Electric Power distribution system

Abstract: The authors results of a research project involving the investigation of power-system harmonic levels on selected distribution circuits of differing load composition on the American Electric Power system (AEP). Over a four-year period, beginning in 1984, the harmonic levels on seven selected distribution circuits were recorded and analyzed providing valuable information on the characteristics of specific loads as well as typical harmonic levels on the three classes of distribution circuits: residential, commercial, and industrial. Analysis of the data obtained through these field measurements indicates typical harmonic distortion levels present during operation of the distribution system. Based on monitored information from the selected circuits, the voltage distortion on the AEP 12.47/7.2 kV distribution system is near 1% at minimum and can be expected to exceed 5% in a small percentage of measurements. In the voltage distortion measurements which exceeded 5% voltage distortion, the fifth harmonic is the major component. >

Novel voltage-controlled grounded resistor

Abstract: The letter presents a new tunable grounded resistor in which a single MOS transistor, operating in the triode region, is linearised via feedback of the drain/source potentials to the gate terminal. Preliminary simulation results show that a biquadratic section realised using the proposed resistor would exhibit less than 0.4% total harmonic distortion (THD) for input signals of 1 Vpp, increasing to 1% for 4 Vpp inputs.

A family of high-swing CMOS operational amplifiers

Abstract: A family of high-swing CMOS operational amplifiers has been developed to maximize the available dynamic range with low supply voltages. Complementary differential pairs are used to achieve an almost rail-to-rail input common-mode voltage range. High linearity is obtained by summing currents so that the small-signal differential-mode voltage gain is constant over the entire input common-mode range. With a 5.0-V power supply, the total harmonic distortion is typically only 1% in a unity-gain configuration with a 4.5-V/sub p-p/ signal. The measured DC offset voltages versus input common-mode range track between the conventional and high-swing versions. These measurements suggest that the commonly feared crossover distortion may not be a problem when the current summation high-swing topology is used. The measured step response characteristics were excellent and exhibited no signs of phase mismatch crossover distortion for high-frequency signals. >

A 20 kHz hybrid resonant power source for the space station

Abstract: A hybrid resonant inverter system is presented that satisfies the steady-state operating requirements of a power source for the proposed International Space Station mobile servicing system. The steady-state behavior of the inverter was analyzed and a method is described for optimizing the design of the resonant network. The performance characteristics such as the total harmonic distortion of the output voltage, RMS output voltage, and the inverter efficiency are presented. The hybrid resonant inverter system maintains an excellent efficiency over varying output-load demand. >

A micropower CMOS continuous-time low-pass filter

Abstract: A continuous-time third-order Butterworth low-pass filter with a nominal cutoff frequency of 945 Hz implemented in a standard 2.4- mu m CMOS process is discussed. The filter is built from fully balanced linearized transconductors and capacitors. The power consumption of the filter, including bias and automatic-tuning circuits, is 12.6 mu W from a single 3-V power supply. It achieves a dynamic range of 63 dB with a total harmonic distortion of less than 0.5%. The total chip area is 1 mm/sup 2/. >

Instantaneous feedback control of a single-phase PWM inverter with nonlinear loads by sine wave tracking

Abstract: The authors propose a novel method for the instantaneous digital control of a PWM (pulse-width modulated) inverter used in an uninterruptible power supply. The output voltage is compared to a sinusoidal reference at each sampling instant to compute in real time through a digital controller the pulse width of the same interval. The closed-loop digital feedback eliminates the steady-state error of the output voltage with a very short computation time. This strategy is verified through computer simulations and provides a very fast compensation of disturbances caused by nonlinear loads, such as rectifiers and triac loads, with low total harmonic distortion and fundamental control. >

An accurate solution to line harmonic distortion produced by AC/DC converters with overlap and DC ripple

Abstract: The author presents a direct method for determining steady-state voltage and current waveforms of an AC/DC converter circuit with overlap and DC ripple. The exact values of individual harmonic magnitudes are calculated easily from waveform discontinuity points by using algebraic additions instead of integrations. The total harmonic distortion of the line voltage at the coupling point is expressed in closed form. The expressions derived can be used with confidence to investigate accurate harmonic levels produced by converter-fed DC drives. >

Harmonics and technical barriers in adjustable speed drives

Abstract: The author reviews the characteristics of harmonics produced by an adjustable-speed drive system as well as methods of reducing them, and presents installation examples. He analyzes the presence of harmonics in both six-pulse and twelve-pulse converter systems and highlights the differences between three-phase and six-phase machines in suppressing these harmonics. The effect of using harmonic filters and a special transformer winding arrangement to reduce harmonics is discussed. Harmonics measurements for two actual installations are presented and analyzed. It is concluded that the order and magnitude of the harmonics generated greatly depend on the drive configuration and system impedance. A three-phase machine connected to a six-pulse system will generate more harmonics than a six-phase machine connected to a twelve-pulse system. Harmonic losses in the stator and rotor must carefully be taken into account during design to keep motor temperature rise within acceptable limits. Harmonics fed back to the power system are reduced by filters connected to the incoming power supply. These filters are relatively large and occupy substantial space in the substation yard. >

General frame of reference for analysis of harmonic distortion in systems with multiple transformer nonlinearities

Abstract: Although the magnetising nonlinearity of power transformers is recognised as a source of harmonic distortion, its effect is often considered negligible, and the analytical models used to assess such effect are extremely simple. A new and more general power system frame of reference which models the coupling between phases and between hamonics is presented in the paper. The model is applied to a practical system wth several transformers to show that when one or more of these elements operate in the saturation region the voltage harmonic levels can be higher than those permitted by legislation.

Basic mechanisms of generation and flow of harmonic signals in balanced and unbalanced three-phase power systems

Abstract: In this paper, the basic mechanisms of generation and flow of harmonic signals in electric power networks are discussed. With regard to generation, the unbalanced operating condition of a sixpulse converter is studied. Guidelines which are applicable in the general case are obtained. With regard to flow of harmonic signals, a new relationship between distortion voltamperes (D) and total harmonic distortion (THD) is derived. This relationship is very similar to the P/? and Q/|V| relations which are well know in electric power flow studies.

On the relationship between the CMRR or PSRR and the second harmonic distortion of differential input amplifiers

Abstract: The results of a harmonic distortion analysis for a differential pair are presented, including the effects of mismatches and of the finite nonlinear common-mode rejection ratio (CMRR) or power-supply rejection ratio (PSRR). Due to mismatches, a differential pair produces second-harmonic distortion. The presence of a finite common-mode gain limits the amount of feedback which can be usefully applied to suppress the harmonic distortion. When the common-mode gain is nonlinear, additional distortion is generated which is not suppressed by the feedback. When the amplifier has to drive a large load and when the supply line impedance is large, the finite PSRR causes similar effects. >

Power factor and harmonic distortion characteristics of energy efficient lamps

Abstract: An evaluation is made of the performance of a class of lamps that are generally classified as energy-saving lamps. It is shown that, when compared with incandescent lamps, these lamps indeed consume less real power and have higher relative illumination. However, the energy-saving lamps operate at a low power factor and produce current distortion which is much higher than the distortion produced by the traditional incandescent lamps. >

10 MHz CMOS OTA-C voltage-controlled quadrature oscillator

Abstract: A quadrature-type voltage-controlled oscillator with operational transconductance amplifiers and capacitors (OTA-C) is presented. A monolithic integrated CMOS test circuit is introduced to verify theoretical results. The attainable frequency range of oscillation of the chip test circuit is 3-10.34 MHz. The total harmonic distortion (THD) is 0.20-1.87% for corresponding peak-to-peak amplitude voltages between 100 mV and 1 V. This amplitude can be controlled either by using a diode connection of two MOS transistors or a proposed nonlinear resistor. >

Current and voltage harmonic measurements and modeling at the Gardner photovoltaic project

Abstract: Measurements on harmonics taken at the Gardner photovoltaic (PV) project during the summer of 1987 are reported. The project includes 28 PV homes, each with a roof-mounted 2 kW PV system, connected to one phase of a 13.8 kV three-phase feeder. The measurements discussed pertain to voltage and current distortion and power flow. Theoretical calculations were carried out in order to study the effects of PV inverters other than the type installed for this study. Computer modeling of the feeder in Gardner indicates, and measurements confirm, that small increases (0.2%) in voltage total harmonic distortion will occur on this feeder with the indicated penetration of PV systems using high-quality, forced-commutation inverters. >

Voltage inverter control applying real-time angle pattern determination

Abstract: A PWM inverter takes into account the harmonic distortion produced by a d.c. link which is not constant. The controller determines switching angles in real time eliminating the need for storing PWM patterns in ROM. This is made possible by a "quick" Fourier transform which allows the determination of switching events in a PWM inverter in real time. The inverter controller develops pattern sets for rejecting selected harmonics and accounts for known fixed harmonic distortion on the d.c. link by determining the set of switching angles for each controlled selected harmonic.

Third Harmonic Distortion of Dielectric Resonator Materials

Abstract: Microwave dielectric materials must have a low third harmonic distortion when they are used for high-power applications. This is because the third harmonic distortion produces a third-order intermodulation distortion which generates interference between signals. In this paper, the measurement results of the third harmonic distortion levels for three types of dielectric resonator materials, (Zr, Sn)TiO4, MgTiO3-CaTiO3 and BaO-PbO-Nd2O3-TiO2, are reported and the equations derived to combine the distortion level and the fourth anharmonic term in the crystal's Hamiltonian. The measured distortion levels have a strong correlation with dielectric loss tangents of the materials. This relationship is also explained in connection with the anharmonic terms in the crystal's Hamiltonian.

New CMOS ota for fully integrated continuous-time circuit applications

Abstract: A new CMOS circuit is proposed for implementing an operational transconductance amplifier (OTA) based on the square-law characteristic of MOS transistors biased in saturation. Simulation results show that a total harmonic distortion of the output current smaller than 1% for differential input signals up to 3.8 Vpp and supply voltages of ± 5 V can be obtained.

Distortion in microwave and RF switches by reverse biased PIN diodes

Abstract: An analytical and experimental study of distortion generated by reverse-biased PIN diodes is presented. The fundamental analytical conclusion is that the magnitude of the reverse bias distortion is inversely proportional to the slope of the C-V characteristic (for second-order distortion) and frequency. This is in contrast to the forward-bias PIN diode switch distortion case where the distortion improves with increasing frequency. The analysis shows that thick PIN diodes tend to exhibit less distortion than thin diodes. Experimental distortion data taken at 1000 MHz on diodes of different thicknesses confirm this result. >

Intermodulation and harmonic distortion in GaInAsP distributed feedback lasers

Abstract: Measurements and calculations of intermodulation and harmonic distortion in 1.3 mu m high-speed distributed feedback lasers at multi GHz modulation frequencies are presented. The observed frequency and power dependence of the distortion levels are well explained by a perturbation analysis of the laser rate equations using parameters derived from the measured small-signal optical response of the laser.

Testing the performance of three-phase induction watthour meters in the presence of harmonic distortion

Abstract: The authors deal with computer-based testing of a three-phase induction watthour meter in the presence of harmonic distortion. Two three-phase harmonic generators produce the distorted current and voltage waveforms. Each waveform has a prespecified harmonic magnitude and phase. Therefore, balanced or unbalanced conditions can be simulated in the testing. A fiber-optic sensor is designed to convert the rotation of the disk of the meter into digital signals to be stored in an IBM PC/AT. A data acquisition system transfers the samples of current and voltage waveforms so that the power and energy can be computed for comparison. Induction watthour meters are shown to be affected by harmonic distortion. The error increases at light loading conditions. For a three-element watthour meter, the maximum negative error was observed when the harmonic current was in phase with the harmonic voltage. This applies to all harmonic orders. The maximum positive error was observed when the harmonic current was shifted by 180 degrees . >

Analysis of distorted unbalanced waveforms in inverter drives

Abstract: A new method is proposed for the analysis of waveforms in a three-phase system when both distortion and unbalance are present. The method makes it possible to obtain the positive and negative-sequence components of each harmonic system present in the three phases. This method provides a way to get information both on the degree of unbalance and on the distortion factors of the waveforms generated by pulsewidth-modulated inverters supplying induction motors. >