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Showing papers on "Power factor published in 2009"


Book
R. Krishnan1
25 Sep 2009
TL;DR: In this article, the authors present a real-time model of a two-phase PMSM transformation to rotor reference frames, where the PMSMs are used to estimate the position of the rotors.
Abstract: PART I: Introduction to Permanent Magnets and Machines and Converters and Control Chapter 1 Permanent Magnets and Machines Permanent Magnets Arrangement of PMs Magnetization of PMs PM ac Machines Fundamentals of Synchronous Machines Fundamental Synchronous Machine Relationships Core Losses Resistive Losses Initial Machine Design Cogging Torque Basic Types of PMSMs Based on Flux Paths Vibration and Noise Chapter 2 Introduction to Inverters and Their Control Power Device DC Input Source DC to ac Power Conversion Real Power Reactive Power Need for Inverter Control Pulse Width Modulation Hysteresis Current Control Space Vector Modulation Inverter Switching Delay Input Power Factor Correction Circuit Four-Quadrant Operation Converter Requirements PART II: Permanent Magnet Synchronous Machines and Their Control Chapter 3 Dynamic Modeling of Permanent Magnet Synchronous Machines Real-Time Model of a Two-Phase PMSM Transformation to Rotor Reference Frames Three-Phase to Two-Phase Transformation Zero Sequence Inductance Derivation Power Equivalence Electromagnetic Torque Steady-State Torque Characteristics Models in Flux Linkages Equivalent Circuits Per Unit Model Dynamic Simulation Small-Signal Equations of the PMSM Evaluation of Control Characteristics of the PMSM Computation of Time Responses Space Phasor Model Chapter 4 Control Strategies for a Permanent Magnet Synchronous Machine Vector Control Derivation of Vector Control Drive System Schematic Control Strategies Chapter 5 Flux-Weakening Operation Maximum Speed Flux-Weakening Algorithm Direct Flux Weakening Parameter Sensitivity Model-Free (Parameter-Insensitive) Flux-Weakening Method Six-Step Voltage and Constant Back EMF Control Strategies for PMSM Direct Steady-State Evaluation Flux Weakening in SMPM and IPM Synchronous Machines Chapter 6 Design of Current and Speed Controllers Current Controller Speed Controller Chapter 7 Parameter Sensitivity and Compensation Introduction Parameter Compensation through Air Gap Power Feedback Control Parameter Compensation by Reactive Power Feedback Control Chapter 8 Rotor Position Estimation and Position Sensorless Control Current Model Adaptive Scheme Sensing by External Signal Injection Current Model-Based Injection Scheme Position Estimation Using PWM Carrier Components PART III: Permanent Magnet Brushless DC Machines and Their Control Chapter 9 PM Brushless DC Machine Modeling of PM Brushless DC Motor Normalized System Equations The PMBDCM Drive Scheme Dynamic Simulation Chapter 10 Commutation Torque Ripple and Phase Advancing Commutation Torque Ripple Phase Advancing Dynamic Modeling Chapter 11 Half-Wave PMBDCM Drives Split Supply Converter Topology C-Dump Topology Variable DC Link Converter Topology Variable Voltage Converter Topology with Buck-Boost Front-End Chapter 12 Design of Current and Speed Controllers Transfer Function of Machine and Load Inverter Transfer Function Transfer Functions of Current and Speed Controllers Current Feedback Speed Feedback Design of Controllers Chapter 13 Sensorless Control of PMBDCM Drive Current Sensing Position Estimation Chapter 14 Special Issues Torque Smoothing Parameter Sensitivity of the PMBDCM Drive Faults and Their Diagnosis Vibration and Noise

847 citations


Journal ArticleDOI
TL;DR: This paper presents a single-phase cascaded H-bridge converter for a grid-connected photovoltaic (PV) application that offers other advantages such as the operation at lower switching frequency or lower current ripple compared to standard two-level topologies.
Abstract: This paper presents a single-phase cascaded H-bridge converter for a grid-connected photovoltaic (PV) application The multilevel topology consists of several H-bridge cells connected in series, each one connected to a string of PV modules The adopted control scheme permits the independent control of each dc-link voltage, enabling, in this way, the tracking of the maximum power point for each string of PV panels Additionally, low-ripple sinusoidal-current waveforms are generated with almost unity power factor The topology offers other advantages such as the operation at lower switching frequency or lower current ripple compared to standard two-level topologies Simulation and experimental results are presented for different operating conditions

728 citations


Journal ArticleDOI
TL;DR: This paper presents a single-phase five-level photovoltaic inverter topology for grid-connected PV systems with a novel pulsewidth-modulated (PWM) control scheme that offers much less total harmonic distortion and can operate at near-unity power factor.
Abstract: This paper presents a single-phase five-level photovoltaic (PV) inverter topology for grid-connected PV systems with a novel pulsewidth-modulated (PWM) control scheme. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals for the switches. A digital proportional-integral current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with rapidly changing atmospheric conditions. The inverter offers much less total harmonic distortion and can operate at near-unity power factor. The proposed system is verified through simulation and is implemented in a prototype, and the experimental results are compared with that with the conventional single-phase three-level grid-connected PWM inverter.

584 citations



Patent
13 May 2009
TL;DR: In this article, a power subsystem is actively optimized to improve total subsystem efficiency in a way that is responsive to changes in load requirements, power supply variations, and subsystem temperature variations.
Abstract: A power subsystem is actively optimized to improve total subsystem efficiency in a way that is responsive to changes in load requirements, power supply variations, and subsystem temperature variations. Detailed, multidimensional power loss models are developed for constituent devices which are then combined into a power subsystem containing a controller and circuity for measuring device operating parameters such as input and output voltage, output current, and temperature. Operating parameters are continually monitored, and set points are correspondingly changed based on the detailed power loss models to achieve maximum overall efficiency for the instantaneous operating state of the system.

472 citations


Journal ArticleDOI
TL;DR: The guidelines for the proper joint design of the compensation network (which is able to cancel out the PV voltage oscillations) and of the main MPPT parameters are provided in this paper.
Abstract: In double-stage grid-connected photovoltaic (PV) inverters, the dynamic interactions among the DC/DC and DC/AC stages and the maximum power point tracking (MPPT) controller may reduce the system performances. In this paper, the detrimental effects, particularly in terms of system efficiency and MPPT performances, of the oscillations of the PV array voltage, taking place at the second harmonic of the grid frequency are evidenced. The use of a proper compensation network acting on the error signal between a reference signal provided by the MPPT controller and a signal that is proportional to the PV array voltage is proposed. The guidelines for the proper joint design of the compensation network (which is able to cancel out the PV voltage oscillations) and of the main MPPT parameters are provided in this paper. Simulation results and experimental measurements confirm the effectiveness of the proposed approach.

410 citations


Journal ArticleDOI
TL;DR: In this paper, two methods of reducing the storage capacitance in the ac/dc power supplies for light emitting diode (LED) lighting were proposed to achieve a long power suppliespsila lifetime.
Abstract: This paper proposes two methods of reducing the storage capacitance in the ac/dc power supplies for light emitting diode (LED) lighting. In doing so, film capacitors can be adopted instead of electrolytic capacitors to achieve a long power suppliespsila lifetime. The voltage ripple of the storage capacitor is intentionally increased to reduce the storage capacitance. The method of determining the storage capacitance for ensuring that the boost power factor correction converter operates normally in the whole input voltage range is also discussed. For the purpose of further reducing the storage capacitance, a method of injecting the third harmonic current into the input current flow is proposed. While ensuring that the input power factor is always higher than 0.9 to comply with regulation standards such as ENERGY STAR, the storage capacitance can be reduced to 65.6% of that with an input power factor of 1. A 60-W experimental prototype is built to verify the proposed methods.

380 citations


Journal ArticleDOI
TL;DR: In this article, a bridgeless power factor correction (PFC) boost rectifier with low common-mode noise is presented. Butler et al. employed a unique multiple-winding, multicore inductor to increase the utilization of the magnetic material and verified the operation and performance of the circuit on a 750-W, universal line experimental prototype operating at 110 kHz.
Abstract: The implementation of a bridgeless power factor correction (PFC) boost rectifier with low common-mode noise is presented in this paper. The proposed implementation employs a unique multiple-winding, multicore inductor to increase the utilization of the magnetic material. The operation and performance of the circuit were verified on a 750-W, universal-line experimental prototype operating at 110 kHz.

261 citations


Patent
Akiyoshi Uchida1
23 Jul 2009
TL;DR: In this article, a power transmission device includes a power supply unit configured to supply power by a resonance frequency for magnetic resonance; a temperature detector provided in the power transmission resonance coil; and a control unit that can determine whether a detected temperature detected by the temperature detector at an elapsed time is within the allowable temperature range at the elapsed time.
Abstract: A power transmission device includes a power supply unit configured to supply power by a resonance frequency for magnetic resonance; a power transmission resonance coil capable of magnetic resonance with a power reception resonance coil in the resonance frequency, the power transmission resonance coil being configured to supply the power from the power supply unit as magnetic field energy caused by the magnetic resonance; a temperature detector provided in the power transmission resonance coil; and a control unit configured to refer to a table stored in a memory expressing an allowable temperature range, determine whether a detected temperature detected by the temperature detector at an elapsed time is within the allowable temperature range at the elapsed time, and stop an operation of the power supply unit when the detected temperature is not within the allowable temperature range.

246 citations


Journal ArticleDOI
TL;DR: In this paper, a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter is presented.
Abstract: This paper presents a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter. The proposed method indirectly generates the compensation current reference by using an equivalent conductance of the fundamental component using APF's dc-link voltage control. The proposed control can selectively choose harmonic current components by real-time fast Fourier transform to generate the compensation current. The compensation current is represented in a rotating coordinate system with chosen switching states from a switching table implemented in a field-programmable gate array. In addition, a three-phase four-wire APF based on a three-level neutral-point-clamped inverter is also presented. The proposed APF eliminates harmonics in all three phases as well as the neutral current. A three-phase three-wire NPC inverter system can be used as a three-phase four-wire system since the split dc capacitors provide a neutral connection. To regulate and balance the split dc-capacitor voltages, a new control method using a sign cubical hysteresis controller is proposed. The characteristics of the APF system with an LCL-ripple filter are investigated and compared with traditional current control strategies to evaluate the inherent advantages. The simulation and experimental results validated the feasibility of the proposed APF.

240 citations


Journal ArticleDOI
TL;DR: A new bridgeless single-phase AC-DC converter with an automatic power factor correction (PFC) is proposed, based on the single-ended primary inductance converter (SEPIC) topology and it utilizes a bidirectional switch and two fast diodes.
Abstract: In this paper, a new bridgeless single-phase AC-DC converter with an automatic power factor correction (PFC) is proposed. The proposed rectifier is based on the single-ended primary inductance converter (SEPIC) topology and it utilizes a bidirectional switch and two fast diodes. The absence of an input diode bridge and the presence of only one diode in the flowing-current path during each switching cycle result in less conduction loss and improved thermal management compared to existing PFC rectifiers. Other advantages include simple control circuitry, reduced switch voltage stress, and low electromagnetic-interference noise. Performance comparison between the proposed and the conventional SEPIC PFC rectifier is performed. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.

Journal ArticleDOI
29 Sep 2009
TL;DR: In this article, an integral battery charger for an electric scooter with high voltage batteries and interior-permanent-magnet motor traction drive is presented, which is derived from the power hardware of the scooter, with the ac motor drive that operates as three phase boost rectifier with power factor correction capability.
Abstract: This paper presents an integral battery charger for an electric scooter with high voltage batteries and interior-permanent-magnet motor traction drive. The battery charger is derived from the power hardware of the scooter, with the ac motor drive that operates as three-phase boost rectifier with power factor correction capability. The control of the charger is also integrated into the scooter control firmware that is implemented on a fixed-point DSP controller. Current-controlled or voltage-controlled charge modes are actuated according to the requirements of the battery management system, that is embedded into the battery pack. With respect to previous integrated chargers, the ac current is absorbed at unitary power factor with no harmonic distortion. Moreover, no additional filtering is needed since the pulsewidth modulation ripple is minimized by means of phase interleaving. The feasibility of the integral charger with different ac motors (induction motor, surface-mounted phase modulation motor) is also discussed, by means of a general model purposely developed for three-phase ac machines. The effectiveness of the proposed battery charger is experimentally demonstrated on a prototype electric scooter, equipped with two Li-ion battery packs rated 260 V, 20 Ah.

Proceedings ArticleDOI
D. Gacio1, J.M. Alonso1, A.J. Calleja1, Jorge Garcia1, Manuel Rico-Secades1 
21 Mar 2009
TL;DR: In this paper, a streetlight LED application is covered, using the Integrated Buck-Flyback Converter developed in previous works, which performs power factor correction from a universal ac source, as well as a control loop using the LM3524 IC, which allows PWM dimming operation mode.
Abstract: Due to the high rise in luminous efficiency that HB-LEDs have experienced in the last recent years, many new applications have been researched. In this paper, a streetlight LED application will be covered, using the Integrated Buck-Flyback Converter developed in previous works, which performs power factor correction (PFC) from a universal ac source, as well as a control loop using the LM3524 IC, which allows PWM dimming operation mode. Firstly, the LED load will be linearized and modeled in order to calculate the IBFC topology properly. Afterwards, the converter will be calculated, presenting the one built in the lab. Secondly, the converter will be modeled in order to build the closed loop system, modeling the current sensor as well in order to develop an adequate controller. Finally, experimental results obtained from the lab tests will be presented.

Journal ArticleDOI
TL;DR: This paper develops a finite-state model predictive control strategy for FC converters that allows one to increase the number of output voltage levels, even at high power factor load conditions and without having to increaseThe number of capacitors and switches.
Abstract: Multilevel converters and, in particular, flying capacitor (FC) converters are an attractive alternative for medium-voltage applications. FC converters do not need complex transformers to obtain the DC-link voltage and also present good robustness properties, when operating under internal fault conditions. Unfortunately, with standard modulation strategies, to increase the number of output voltage levels of FC converters, it is necessary to increase the number of cells and, hence, the number of capacitors and switches. In this paper, we develop a finite-state model predictive control strategy for FC converters. Our method controls output currents and voltages and also the FC voltage ratios. This allows one to increase the number of output voltage levels, even at high power factor load conditions and without having to increase the number of capacitors and switches. Experimental results illustrate that the proposed algorithm is capable of achieving good performance, despite possible parameter mismatch.

Patent
05 Oct 2009
TL;DR: A power line monitoring device is mounted to a power line as discussed by the authors, and the ground reference point of the circuitry is electrically coupled to the power line, so that there is a substantially equalized or uniform electric field around the device.
Abstract: A power line monitoring device is mounted to a power line. The device includes circuitry for monitoring the power line and communicating information regarding the power line. A ground reference point of the circuitry is electrically coupled to the power line. Therefore, the monitoring device, including its circuitry, has substantially the same voltage potential as the power line. Accordingly, there is a substantially equalized or uniform electric field around the device The substantially equal voltage potential and electric field allow communications with the monitoring device to have reduced noise and interference, as compared to other devices that have different voltage potentials than their corresponding power lines. A pad of semi-conductive material may be disposed between the power line and the electrical conductors to slow a rate of change of the voltage potential of the device circuitry when mounting the device to the power line, minimizing risk of corona discharge.

Journal ArticleDOI
TL;DR: In this paper, a maximum wind power extraction for a wind energy conversion system composed of a wind turbine, a squirrel-cage induction generator, and a matrix converter is presented.
Abstract: This paper focuses on maximum wind power extraction for a wind energy conversion system composed of a wind turbine, a squirrel-cage induction generator, and a matrix converter (MC). At a given wind velocity, the mechanical power available from a wind turbine is a function of its shaft speed. In order to track maximum power, the MC adjusts the induction generator terminal frequency, and thus, the turbine shaft speed. The MC also adjusts the reactive power transfer at the grid interface toward voltage regulation or power factor correction. A maximum power point tracking (MPPT) algorithm is included in the control system. Conclusions about the effectiveness of the proposed scheme are supported by analysis and simulation results.

Journal ArticleDOI
TL;DR: Simulation and experimental results show that the proposed combined configuration can effectively stabilize system voltage, correct power factor, and suppress harmonic currents.
Abstract: In this paper, a combined system of static Var compensator (SVC) and active power filter (APF) was proposed. The system has the function of power factor correction, voltage stability, and harmonic suppression. The SVC, which consists of delta-connected thyristor-controlled reactor (TCR) and Y-connected passive power filter (PPF), is mainly for voltage stability and power factor correction. The small rating APF is used to filter harmonics generated by the nonlinear load and the TCR in the SVC and to suppress possible resonance between the grid and the PPFs. The configuration and principle of the combined system were discussed first, and then, the control method of the combined system was presented. An optimal nonlinear proportional-integral control was proposed to improve the dynamic response and decrease the steady-state error of the SVC. Harmonic detection with precompensation method and improved generalized integrator control were proposed to improve the performance of APF. The new combined system is compared to classical SVC. It is implemented in a 200-kVA prototype in the laboratory. Simulation and experimental results show that the proposed combined configuration can effectively stabilize system voltage, correct power factor, and suppress harmonic currents.

Journal ArticleDOI
TL;DR: This paper provides a comprehensive guideline for the design of a single-phase PFC targeting for minimal volume, as it is highly relevant for ultracompact integrated systems.
Abstract: This paper provides a comprehensive guideline for the design of a single-phase PFC targeting for minimal volume, as it is highly relevant for ultracompact integrated systems. It is shown, how different operation modes (continuous, boundary, and discontinuous conduction mode) may influence the design and consequently the achieved power density. Furthermore, the effect of interleaving of several boost stages is analyzed as a measure for compactness increase. Finally, the selection of the appropriate switching frequency in order to achieve an overall optimized system is discussed. In this way, the design of the crucial components is carried out, namely, the boost inductor, including a volume optimization through a thermal connection to the heat sink; the output capacitor considering the rms current stress; and the input filter, which is designed for compliance with high-frequency electromagnetic compatibility standards, taking into account the quasi-peak detection measurement of the test receiver equipment.

Journal ArticleDOI
TL;DR: This paper deals with the hardware implementation of a shunt active filter (SAF) for compensation of reactive power, unbalanced loading, and harmonic currents and its effectiveness with Adaline-based control for load compensation.
Abstract: This paper deals with the hardware implementation of a shunt active filter (SAF) for compensation of reactive power, unbalanced loading, and harmonic currents. SAF is controlled using an adaptive-linear-element (Adaline)-based current estimator to maintain sinusoidal and unity-power-factor source currents. Three-phase load currents are sensed, and using least mean square (LMS) algorithm-based Adaline, online calculation of weights is performed and these weights are multiplied by the unit vector templates, which give the fundamental-frequency real component of load currents. The dc bus voltage of voltage source converter (VSC) working as a SAF is maintained at constant value using a proportional-integral controller. The switching of VSC is performed using hysteresis-based pulsewidth-modulation indirect-current-control scheme, which controls the source currents to follow the derived reference source currents. The practical implementation of the SAF is realized using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. The MATLAB-based simulation results and implementation results are presented to demonstrate the effectiveness of the SAF with Adaline-based control for load compensation.

Journal ArticleDOI
TL;DR: In this article, the authors proposed new direct power control (DPC) strategies for three-phase DC/AC converters with improved dynamic response and steady-state performance, where the lookup table was optimized to improve power control and reduce current distortion.
Abstract: This paper proposes new direct power control (DPC) strategies for three-phase DC/AC converters with improved dynamic response and steady-state performance. As with an electrical machine, source and converter flux, which equal the integration of the respective source and converter voltage, are used to define active and reactive power flow. Optimization of the lookup table used in conventional DPC is outlined first so as to improve power control and reduce current distortion. Then, constant switching frequency DPC is developed where the required converter voltage vector within a fixed half switching period is calculated directly from the active and reactive power errors. Detailed angle compensation due to the finite sampling frequency and the use of an integral controller to further improve the power control accuracy are described. Both simulation and experimental results are used to compare conventional DPC and vector control, and to demonstrate the effectiveness and robustness of the proposed control strategies during active and reactive power steps, and line inductance variations.

Journal ArticleDOI
TL;DR: This paper proposes a novel and simple direct power control (DPC) scheme of a three-phase pulsewidth-modulated rectifier without the use of a predefined switching table, and proves the validity of the proposed DPC scheme which is much better than the classical DPC.
Abstract: This paper proposes a novel and simple direct power control (DPC) scheme of a three-phase pulsewidth-modulated rectifier without the use of a predefined switching table. The converter switching state selection is based on fuzzy logic rules, using the instantaneous active and reactive power tracking errors as fuzzy logic variables. The basic idea of fuzzy rules synthesis is based on the knowledge of the instantaneous variation of active and reactive power. According to the input fuzzy variables and in a specific moment, the best switching state of the converter is chosen to restrict the instantaneous active and reactive power tracking errors simultaneously, for maintaining the DC-bus voltage close to the reference value and guarantying the unity-power-factor operation. The main advantages of the proposed DPC scheme, compared to the classical one, are that it is not necessary to use hysteresis comparators, and smooth control of active and reactive power is obtained during all sectors. Finally, the developed DPC was tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance, and verify the validity of the proposed DPC scheme which is much better than the classical DPC.

Journal ArticleDOI
TL;DR: In this article, a simple coordinated control method for leveling the fluctuations of combined power output from multiple photovoltaic (PV) systems is proposed, where the conflicting objective of output power leveling and acquisition power increase is achieved by means of the proposed method.
Abstract: A photovoltaic (PV) system's power output is not constant and fluctuates depending on weather conditions. Fluctuating power causes frequency deviations and reduction in reliability of the isolated power utility or microgrid when large output power from several PV systems is penetrated in the utility. In this paper, to overcome these problems, a simple coordinated control method for leveling the fluctuations of combined power output from multiple PV systems is proposed. The conflicting objective of output power leveling and acquisition power increase is achieved by means of the proposed method. Here, output power command is generated in two steps: central and local. Fuzzy reasoning is used to generate the central leveling output power command considering insolation, variance of insolation, and absolute average of frequency deviation. In local step, a simple coordination is maintained between central power command and local power commands by producing a common tuning factor. Power converters are used to achieve the same output power as local command power employing PI control law for each of the PV generation systems. The proposed method is compared with the method where a modified maximum power point tracking control is used for smoothing the short-term change in each of the PV system's output. Simulation results show that the proposed method is effective for leveling output power fluctuations and feasible to reduce the frequency deviations of the isolated power utility to maintain reliability.

Journal ArticleDOI
TL;DR: In this paper, the effect of the discontinuity due to the effective duty cycle derived from the device switching time at the mode change is analyzed, and a technique to compensate the output voltage transient due to this discontinuity is proposed.
Abstract: With the advent of battery-powered portable devices and mandatory adoption of power factor correction, noninverting buck-boost converters are garnering lots of attention. Conventional two-switch or four-switch noninverting buck-boost converters choose their operation modes by measuring input and output voltage magnitude. The criterion for the selection of the operation mode can cause higher output voltage transients in the neighborhood, where input and output are close to each other. For the mode selection, due to the voltage drops raised by the parasitic components, it is not enough just to compare the magnitude of input and output voltages. In addition, the difference in the minimum and maximum effective duty cycles between controller output and switching device yields discontinuity at the instant of mode change. Moreover, the different properties of output voltage versus a given duty cycle of buck and boost operating modes contribute to the output voltage transients. In this paper, the effect of the discontinuity due to the effective duty cycle derived from the device switching time at the mode change is analyzed. A technique to compensate the output voltage transient due to this discontinuity is proposed. In order to attain additional mitigation of output transients and a linear input/output voltage characteristic in buck and boost modes, the linearization of DC gain of the large-signal model in boost operation is analyzed as well. Analytical, simulation, and experimental results are presented to validate the proposed theory.

Journal ArticleDOI
TL;DR: In this paper, a systematic analysis of line-current distortions of the discontinuous-conduction-mode and the continuousconductionmode boundary boost power factor correction converter due to valley switching (VS) and switching-frequency limitation, where VS is either maintained or lost after the onset of switching frequency limitation, is provided.
Abstract: A systematic analysis of line-current distortions of the discontinuous-conduction-mode and the continuous-conduction-mode boundary boost power factor correction converter due to valley switching (VS) and switching-frequency limitation, where VS is either maintained or lost after the onset of switching-frequency limitation, is provided. Closed-form expressions for the line current are derived. It is shown that if the switching frequency is limited and VS is not maintained, the line current is more distorted with voltage-mode control than with current-mode control. The effects of line-current distortions are demonstrated with both simulation and experimental results.

Journal ArticleDOI
TL;DR: An active power filter and static VAr compensator with active power generation capability, has been implemented using a 27-level inverter that can compensate load currents with high harmonic content and low power factor, resulting in sinusoidal currents from the source.
Abstract: An active power filter and static var compensator with active power generation capability has been implemented using a 27-level inverter. Each phase of this inverter is composed of three ldquoHrdquo bridges, all of them connected to the same dc link and their outputs connected through output transformers scaled in the power of three. The filter can compensate load currents with a high harmonic content and a low power factor, resulting in sinusoidal currents from the source. To take advantage of this compensator, the dc link, instead of a capacitor, uses a battery pack, which is charged from a photovoltaic array connected to the batteries through a maximum power point tracker. This combined topology make it possible to produce active power and even to feed the loads during prolonged voltage outages. Simulation results for this application are shown, and some experiments with a 3-kVA device are displayed.

Patent
10 Feb 2009
TL;DR: In this article, a power conversion system includes a controller to provide power control to a converter, and a distortion mitigation circuit, where the controller may selectively disable the power control in response to a sense signal from the power path.
Abstract: In one embodiment, a power conversion system includes a controller to provide power control to a converter, and a distortion mitigation circuit. In another embodiment, a system includes a converter to transfer power between a power source and a load having fluctuating power demand, and a controller to provide power control, where the controller may selectively disable the power control. In another embodiment, a power conversion system includes a controller to generate a drive signal to provide power control to a power path in response to a sense signal from the power path, where the sense signal is taken from other than the input of the power path, or the drive signal is applied to the power path at other than a first power stage.

Journal ArticleDOI
TL;DR: This paper presents a compact battery-powered switched-reluctance motor (SRM) drive for an electric vehicle with voltage-boosting and on-board power-factor-corrected-charging capabilities, and good winding current and speed dynamic responses of the SRM drive are obtained.
Abstract: This paper presents a compact battery-powered switched-reluctance motor (SRM) drive for an electric vehicle with voltage-boosting and on-board power-factor-corrected-charging capabilities. Although the boost-type front-end DC/DC converter is externally equipped, the on-board charger is formed by the embedded components of SRM windings and converter. In the driving mode, the DC/DC boost converter is controlled to establish boostable well-regulated DC-link voltage for the SRM drive from the battery. During demagnetization of each stroke, the winding stored energy is automatically recovered back to the battery. Moreover, the regenerative braking is achieved by properly setting the SRM in the regenerating mode. The controls of two power stages are properly designed and digitally realized using a common digital signal processor. Good winding current and speed dynamic responses of the SRM drive are obtained. In addition, the static operation characteristics are also improved. In the charging mode, the power devices that were embedded in the SRM converter and the three motor-phase windings are used to form a buck-boost switch-mode rectifier to charge the battery from utility with good power quality. All constituted circuit components of the charger are placed on board, and only the insertion of power cords is needed.

Patent
17 Feb 2009
TL;DR: In this article, a power scavenging device attached to an overhead power cable and a support pole is described, which includes a nonconducting outer body and a first capacitor and a second capacitor that are connected in series forming a voltage divider.
Abstract: A power scavenging device attaches to an overhead power cable and a support pole. The power scavenging device includes a non-conducting outer body and a first capacitor and a second capacitor that are connected in series forming a voltage divider. A voltage source converter is electrically connected to the output of the power scavenging device. The voltage source converter outputs a regulated power.

Journal ArticleDOI
TL;DR: This proposal uses the existing capacitor bank to build a hybrid filter in which the complementary compensation is performed by the active filter and shows very good behavior in steady-state and transient conditions.
Abstract: The problem of reactive power and harmonics in the medium voltage level of a power distribution system is considered in this paper. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The alternative of a shunt hybrid active filter connected to the 13.8-kV level to enhance the power quality is analyzed in this paper. This proposal uses the existing capacitor bank to build a hybrid filter in which the complementary compensation is performed by the active filter. The performance of the hybrid filter is evaluated with extensive simulations considering reactive power, harmonics, and unbalance compensation. It shows very good behavior in steady-state and transient conditions.

Patent
Yasushi Amano1, Shinji Ichikawa1
13 Oct 2009
TL;DR: A power supply system that includes a power supply coil and a power receiving coil is described in this paper, where the authors present an adjustment unit that adjusts the relative position of the power supply-side resonance coil with respect to the power receiving-side resonant coil.
Abstract: A power supply system that includes: a power supply coil and a power supply-side resonance coil that are provided at a facility; a power receiving coil and a power receiving-side resonance coil that are provided for a mobile unit; a power supply-side detection unit that detects a position of the power supply-side resonance coil; a power receiving-side detection unit that detects a position of the power receiving-side resonance coil; and an adjustment unit that adjusts a relative position of the power supply coil with respect to the power supply-side resonance coil and a relative position of the power receiving coil with respect to the power receiving-side resonance coil on the basis of the position of the power supply-side resonance coil and the position of the power receiving-side resonance coil.