Sinusoidal Current Source Research Articles

Application of shunt active power filter for harmonic reduction and reactive power compensation in three‐phase four‐wire systems

This study deals with the analysis and implementation of compensation algorithms applied to a shunt active power filter, which uses three single-phase full-bridge converters sharing the same dc-bus voltage. The shunt filter is applied to three-phase four-wire systems, performing harmonic current suppression, reactive power compensation and power factor improvement. In addition, load unbalances compensation is also carried out. Two different control strategies are presented. In the first strategy, which is called independent current control, the currents of the three-phase power source are independently compensated performing harmonic suppression and load reactive power compensation, that is, the three-phase four-wire system is treated as three independent single-phase systems. In the second strategy, in addition to harmonic suppression and load reactive power compensation, the shunt filter also performs load unbalance compensation, resulting in sinusoidal and balanced source currents. The compensating algorithms are evaluated by means of several experimental test conditions, in order to validate the theoretical development and analyse the performance of the shunt filter.

Fuzzy Logic Controlled Shunt Active Power Filter for Harmonic Compensation and Power Quality Improvement

In this paper, a shunt active power filter based on fuzzy logic controller is modeled, simulated, and tested. The fundament of Instantaneous Reactive Power Algorithm is used for extracting compensated reference harmonic current. A fuzzy logic controlled shunt Active Power Filter (SAPF) Using Hysteresis Band Current (HBC) is applied to regulate the DC capacitor voltage of (SAPF) in order to improve the active filter dynamic, to ensure sinusoidal source currents and to produce a high power quality. The main goal of the proposed active filtering system is to maintain the THD well within IEEE-519 on harmonics levels. Simulation results through MATLAB/Simulink are presented and interpreted. It is demonstrated that the fuzzy logic controller improves the performance of the active power filter. The implementation of a shunt active power filter has high performance characteristics by using dSPACE system.

Series–Parallel Autoregulated Charge-Balancing Rectifier for Multioutput Light-Emitting Diode Driver

A series-parallel autoregulated rectifying circuit is proposed for a multioutput dc/dc light-emitting diode (LED) driver. The series-parallel autoregulated characteristics balance the charge in the secondary blocking capacitors automatically. Hence, with the proposed rectifier and secondary-side multiwinding transformer, a multioutput LED driver with precise current-sharing capability is achieved even for multiple LED strings with different voltages. The operating principle of the rectifier is analyzed with a sinusoidal current source and is verified with a four-output LLC dc/dc LED driver. This proposed rectifier can be applied to other converters featuring a high-frequency current source link at the primary side.

A Capacitance-to-Digital Converter with Sinusoidal Excitation Suitable for Series RC Sensors

Abstract A new Capacitance-to-Digital Converter (CDC) applicable for series RC sensors that requires/prefers sinusoidal excitation is proposed in this paper. The CDC presented works based on a dual-slope technique and it gives a digital output as a function of unknown capacitance of a series RC sensor, i.e., a capacitive sensor with a capacitor and a resistor in series in its electrical equivalent circuit. Output of the CDC is not sensitive to the series resistor. The CDC is useful for grounded as well as floating capacitive sensors, which needs to be excited with a sine wave for best performance. Applications of such capacitive sensors include ice detection, sterility testing of packed food products, etc. A sinusoidal Howland current source can be used to excite a grounded capacitive sensor while a simple current source with a special stabilization scheme that suppresses the effect due to static errors of opamp has been developed for floating capacitive sensor and presented in this paper. A prototype of the proposed CDC for a floating capacitive sensor has been built and tested in the laboratory. Measurement results for the sensor capacitance showed a worst case error of 0.13% for a range of 100 pF, proving the efficacy of the proposed scheme.

Performance Analysis and Technical Feasibility of an iUPQC in Industrial Grids

The iUPQC is a Unified Power Quality Conditioner in which the series converter emulates a sinusoidal current source and the shunt converter emulates a sinusoidal voltage source. This approach provides indirect power quality compensation of the load voltage and the source current. Recent studies have suggested that the iUPQC has technical advantages in comparison with the conventional UPQC due to its reduced switching frequency characteristic. In this paper, these technical advantages are investigated. Thus, the iUPQC performance is verified through a 150 kVA industrial equipment and technical design specifications are discussed: the iUPQC power circuit design, the converters arrangement and the driver configuration. Experimental results are provided to validate the technical feasibility and power quality compensation performance.

A novel active power quality compensator topology with DC voltage balancer for electrified railways

AbstractThis paper proposes a novel active power quality compensator (APQC) topology with a DC voltage balancer for electrified railways. The APQC is composed of a three‐leg structure with two common DC capacitors. Two legs perform as two half‐bridge inverters, which compensate the unbalanced active, reactive, and harmonic currents on the source side in the traction substation. The third leg controls two common DC capacitor voltages with a small amount of the output currents. Therefore, the current rating of the third leg can be reduced as compared to that of the already proposed three‐leg structured APQC. In the control algorithm of the two half‐bridge inverters, a strategy based on constant DC capacitor voltage control is used, which does not need any calculation blocks of the unbalanced active, reactive, and harmonic components of the load current to perform the APQC operation. Thus we offer the simplest algorithm for the proposed APQC. The basic principle of the proposed APQC topology with the DC voltage balancer is discussed in detail, and then confirmed by digital computer simulation using the PSIM software. A prototype experimental model is constructed and tested. Experimental results demonstrate that the proposed APQC can achieve balanced and sinusoidal source currents on the primary side of the Scott transformer in traction substations for electrified railways. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Designing and implementing bioimpedance spectroscopy device by measuring impedance in a mouse tissue

Studies show that any complications including hemorrhage, lack of blood supply, lack of oxygen supply and death of cells in a tissue, will have a clear effect on electrical properties of that tissue. Thus, by measuring impedance of a set of tissues, potential problems of the damaged tissue may be found. Since electrical impedance is closely related to the measuring frequency, obviously, every tissue exhibits its own specific impedance according to its electrical properties at each frequency. This research project investigates design and manufacture method of a device for measuring tissue impedance at different frequencies. To this end, design of a multi frequency sinusoidal current source is required. This current source is built using a single harmonic Generator sample (Direct Digital Synthesizer AD9835) with working frequency (design-point frequency) between 1 Hz and 10 MHz and accuracy of 1 Hz and microcontroller (PIC16F628) capability. For measurement and display of tissue impedance, ARM AT91SAMs256 microcontroller was used. Thus, with this hardware created, it shows that there are significant impedance changes between mouse tissues.

Imposed Sinusoidal Source and Load Currents for an Indirect Matrix Converter

A new strategy for indirect matrix converters which allows an optimal control of source and load currents is presented in this paper. This method uses the commutation state of the converter in the subsequent sampling time according to an optimization algorithm given by a simple cost functional and the discrete system model. The control goals are regulation of output current according to an arbitrary reference and also a good tracking of the source current to its reference which is imposed to have a sinusoidal waveform with low distortion. Experimental results support the theoretical development.

Control of a Matrix Converter With Imposed Sinusoidal Source Currents

A new strategy for matrix converters which allows optimal control of source and load currents is presented in this paper. This method uses the commutation state of the converter in the subsequent sampling time, according to an optimization algorithm given by the discrete system model and a simple cost function. The control goals include regulation of output current using an arbitrary reference and good tracking of the source current to its reference, to achieve a sinusoidal waveform. Experimental results from a 7.5 kW prototype support the theoretical development.

Modelling, Simulation and Implementation of Optimisation Algorithm Based Shunt Active Filter for Harmonics Mitigation of Non-Linear Loads

The use of active power filters is widely accepted and implemented as a solution to the power quality problems in utility, industry and commercial applications. This paper presents an optimisation based control algorithm for determining the reference compensation currents of shunt active power filter (SAPF) to maintain sinusoidal source currents supplied to non-linear loads and to maintain the total harmonic distortion (THD) less than 5% according to IEEE-519 standard and improve power factor. Optimisation is due to the combined effect of perfect harmonic cancellation (PHC) and unity power factor (UPF) strategies. Reference compensation current is calculated through MATLAB using discrete Fourier transform. The optimisation-based control algorithm gives the best power factor while satisfying the constraints such as THD limits and average power balance of source currents. It is also flexible to adopt different compensation characteristics based on the supply voltage conditions. The proposed technique is implemented using MATLAB/Simulink and optimisation tool boxes for both balanced and unbalanced load conditions. The algorithm is validated by using a prototype of digital signal processor (TMS320F2812) based SAPF. Detailed experimental results are presented.

A Simple Two-Channel LED Driver With Automatic Precise Current Sharing

A simple rectifying circuit for an isolated two-channel LED driver without active current-sharing control is proposed. An alternating current source can be used to generate a two-channel LED driver with the proposed rectifying structure. With the proposed H-bridge rectifier and a block capacitor in series with the secondary side winding of the transformer, the currents in two LED strings are shared automatically even for different LED strings with different voltage drops. The operation principle of the rectifier is analyzed with a sinusoidal current source, and it is verified with a series-parallel resonant ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> ) dc/dc converter. This proposed rectifier can be applied to other converters featuring a high-frequency current source link.

Power quality enhancement utilising single-phase unified power quality conditioner: digital signal processor-based experimental validation

This study is based on a single-phase unified power quality conditioner (UPQC) to enhance power quality problem in single-phase systems. A simple control approach is implemented and validated through simulation as well as experimental studies. A laboratory prototype of UPQC is designed and developed using a digital signal processor. The performance of UPQC is validated experimentally under several operating conditions. It is found that the UPQC in single-phase system effectively compensates the important power quality issues, such as the load reactive power, load current harmonics, voltage harmonics, voltage sag, voltage swell and voltage flicker. Under distorted source voltage having total harmonics distortion (THD) of 14.1% with a non-linear load producing a distorted current (THD of 30.98%), the UPQC simultaneously compensates these harmonics resulting sinusoidal source current (THD of 3.77%) and load voltage (THD of 2.54%).

Active shunt current shaping scheme for multiple paralleled DC–DC converters

SUMMARYA new shunt current shaping scheme for multiple paralleled dc–dc converters is proposed in this paper. The current command for the shunt current shaper is indirectly obtained by forcing the source current to follow the demanded sinusoidal signal. The amplitude of the demanded sinusoidal source current that is in‐phase with the source voltage can be determined from the sensed load currents of the post‐stage dc–dc converters. Neither high‐order filters nor time‐consuming computations are required. The shunt current shaper supplies all the harmonics and the out‐of‐phase fundamental of the distorted input current and the power source only supplies the in‐phase fundamental component. Experimental results on a prototype system verify the feasibility of the presented scheme. The implemented shunt current shaper demonstrates an efficiency of 92% and a nearly unity power factor at the utility side. Copyright © 2011 John Wiley &amp; Sons, Ltd.

A 3.9 mW 25-Electrode Reconfigured Sensor for Wearable Cardiac Monitoring System

A low power highly sensitive Thoracic Impedance Variance (TIV) and Electrocardiogram (ECG) monitoring SoC is designed and implemented into a poultice-like plaster sensor for wearable cardiac monitoring. 0.1 Ω TIV detection is possible with a sensitivity of 3.17 V/Ω and SNR > 40 dB. This is achieved with the help of a high quality (Q-factor > 30) balanced sinusoidal current source and low noise reconfigurable readout electronics. A cm-range 13.56 MHz fabric inductor coupling is adopted to start/stop the SoC remotely. Moreover, a 5% duty-cycled Body Channel Communication (BCC) is exploited for 0.2 nJ/b 1 Mbps energy efficient external data communication. The proposed SoC occupies 5 mm × 5 mm including pads in a standard 0.18 μm 1P6M CMOS technology. It dissipates a peak power of 3.9 mW when operating in body channel receiver mode, and consumes 2.4 mW when operating in TIV and ECG detection mode. The SoC is integrated on a 15 cm × 15 cm fabric circuit board together with a flexible battery to form a compact wearable sensor. With 25 adhesive screen-printed fabric electrodes, detection of TIV and ECG at 16 different sites of the heart is possible, allowing optimal detection sites to be configured to accommodate different user dependencies.

Particle Swarm Optimization-Based Feedback Controller for Unified Power-Quality Conditioner

The unified power-quality conditioner (UPQC) is used to provide balanced and sinusoidal source currents and load voltages under unbalanced and distorted three-phase supply voltages and load currents in a power distribution network. In this paper, a particle swarm optimization-based feedback controller is designed for UPQC. This feedback controller has optimal performance in various operating conditions and is robust to parametric uncertainties when compared to the conventional feedback controllers, such as the linear quadratic regulator. The proposed method is implemented on a distribution system and detailed simulation and experimental results are presented.

Rotor Failures Diagnosis of Squirrel Cage Induction Motors with Different Supplying Sources

The growing application and the numerous qualities of induction motors (IM) in industrial processes that require high security and reliability levels has led to the development of multiple methods for early fault detection. However, various faults can occur, such as stator short-circuits and rotor failures. Traditionally the diagnosis machine is done through a sinusoidal power supply, in the present paper we study experimentally the effects of the rotor failures, such as broken rotor bars in function of the ac supplying, the load and show the impact of the converter from diagnosis of the machine. The technique diagnosis used is based on the spectral analysis of stator currents or stator voltages respectively according to the types of induction motor ac supplying. So, four different ac supplying are considered: ? the IM is directly by the balanced three-phase network voltage source, ? the IM is fed by a sinusoidal current source given the controlled by hysteresis, ? the IM is fed (in open loop) by a scalar control imposing through ratio V/f=constant, ? the IM is controlled through a vector control using space vector pulse width modulation (SVPWM) technique inverter with an outer speed loop.

Instantaneous Reactive Power Theory: A Reference in the Nonlinear Loads Compensation

The instantaneous reactive power theory was published 25 years ago, in an IEEE Transactions. Since then, it has been the most used in nonlinear load compensation with active power filters. Its application allows constant source power to be obtained after compensation in a simple way. Moreover, some researches have showed up some limitations of the theory, i.e., it goes optimally with source voltage balanced and sinusoidal, but not so good with source voltage unbalanced and/or nonsinusoidal, since the source current obtained is not balanced and sinusoidal. This paper presents a new compensation strategy in phase coordinates, equivalent to the original theory's one. Its simplicity, due to the nonnecessity of coordinate mathematical transformation, makes easier the modifications necessary to obtain alternative compensation objectives. In this way, this paper presents those modifications and derives compensation strategies that obtain alternative compensation objectives: unity power factor or balanced and sinusoidal source current. Finally, compensation strategies are applied to a practical power system, and the results are presented.

Three Phase AC-Line Converter for the Flywheel Energy Storage System

he paper presents a three-phase rectifier with sinusoidal source current which enables energy to be fed back to the AC supply network. It has been used in a flywheel energy storage system. The principle of operation and control methods of the three-phase rectifier are discussed. The experimental setup employing a DSP controller co-operating with CPLD device is described. Results of experimental investigation for both the steady and transient states are presented in the concluding section.

New Control Method of Active Power Quality Compensator with Reduced-Capacity Three-Leg Inverter for Electrified Railways

This paper proposes a new control method for reducing the capacity of an active power quality compensator with a three-leg inverter used in electrified railways. In the proposed control method, the fundamental reactive and unbalanced-active components of the load currents are detected. The non-active and unbalanced-active components are compensated on the source side with the fundamental reactive power control. This reactive power control reduces the capacity of the three-leg inverter, which performs the active power quality compensator. The basic principle of the proposed control method is discussed in detail, and then confirmed by digital computer simulation using the PSIM software. A reduced-scale experimental model is constructed and tested. Experimental results demonstrate that the balanced sinusoidal source currents with the power factor of 0.9 are obtained, reducing the capacity of the three-leg inverter by 13% as compared to the already proposed control method.

Shielding Effectiveness of the Gas-Insulated Bus Duct for Transient EM Fields Generated in a GIS During Switching Operations

Characterization and quantification of the transient electromagnetic (EM) fields generated in a gas-insulated substation (GIS) during switching operations has become important in recent years. This is due to increased use of sensitive electronic devices in the control circuitry of such substations. In this paper, a numerical model based on the finite-difference time-domain technique has been developed to compute the EM field emission from the gas-insulated bus duct through nonmetallic flange of the support insulator during switching operations. The shielding effectiveness (SE) of the bus duct/section for the EM fields has been evaluated using a derivative Gaussian current source and a short time sinusoidal current source. The effect of variations in dimensions of the slot formed by the nonmetallic flange as well as electromagnetic properties of the insulator/bus duct enclosure on SE has been studied. The variation in field pattern along the axis of bus duct at various distances due to the transient currents of different frequencies has been analyzed. The enhancement factor for the EM field levels due to the presence of a metallic structure has been reported. Finally, emission levels are calculated for the very fast transient currents generated in a 245 kV GIS and their dominant frequencies have been identified.