Showing papers on "Current sensor published in 2018"

Current Sensor Fault Diagnosis and Tolerant Control for VSI-Based Induction Motor Drives

Abstract: Fault-tolerant control is attracting more interests due to its capability of increasing the reliability of voltage source inverters (VSI). Fault detection, localization, and tolerant control schemes of current sensor are presented for high-fault-tolerance induction motor drives. Generally, three-phase current sensors are used in high-power inverters; nevertheless, failure of current sensors degrades the performance and reliability and even leads to the breakdown of the vector control system due to the fact that flux angle cannot be estimated correctly. The proposed scheme integrates three independent observers, taking a -phase current, b -phase current, and c -phase current as inputs, respectively. The observers are capable of online monitoring the state of current sensors under normal operation. Furthermore, after one or even two current sensors getting faulty, the observers can detect and localize the faults and switch the system to tolerant vector control mode even with only one healthy phase current sensor available. Hence, it is very attractive in some safety crucial applications. Stability and convergence of the observer are analytically derived and verified. A dSpace-based 1.1-kW induction motor variable-speed system is set up for the experiment, and experimental results demonstrate the validity of the proposed algorithm.

Standalone Photovoltaic Water Pumping System Using Induction Motor Drive With Reduced Sensors

Abstract: A simple and efficient solar photovoltaic (PV) water pumping system utilizing an induction motor drive (IMD) is presented in this paper. This solar PV water pumping system comprises two stages of power conversion. The first stage extracts the maximum power from a solar PV array by controlling the duty ratio of a dc–dc boost converter. The dc bus voltage is maintained by the controlling the motor speed. This regulation helps in the reduction of motor losses by reducing motor currents at higher voltage for the same power injection. To control the duty ratio, an incremental conductance based maximum power point tracking (MPPT) control technique is utilized. A scalar-controlled voltage source inverter serves the purpose of operating an IMD. The stator frequency reference of IMD is generated by the proposed control scheme. The proposed system is modeled, and its performance is simulated in detail. The scalar control eliminates the requirement of a speed sensor/encoder. Consequently, the need of motor current sensor is also eliminated. Moreover, the dynamics are improved by an additional speed feedforward term in the control scheme. The proposed control scheme makes the system inherently immune to the variation in the pump constant. The prototype of PV-powered IMD emulating the pump characteristics is developed in the laboratory to examine the performance under different operating conditions.

A Signal-Based Fault Detection and Tolerance Control Method of Current Sensor for PMSM Drive

Abstract: A new fault detection and tolerance (FDT) control strategy for current sensors of permanent magnet synchronous machine drive in filed-oriented control mode was introduced in this paper, based on the reasonable estimation of current amplitude. The propounded method can be applied to deal with a single or double signal-loss faults (two concurrent or independent faults), and shows the capability of online revision to gain variation and zero offset. Compared with the conventional observer-/model-based fault detection methods for current sensors, the proposed method only requires the information of three-phase currents and the position of motor rotor, instead of an accurate system model with explicit parameters. The improved simplicity and reliability makes this new method especially useful for FDT of current sensors in a real-time control system with limited computational capability. The feasibility and robustness of the proposed approach has been validated by extensive experiments under a wide variety of working conditions.

Improved Saliency-Based Position Sensorless Control of Interior Permanent-Magnet Synchronous Machines With Single DC-Link Current Sensor Using Current Prediction Method

Abstract: This paper presents an improved saliency-based position sensorless drive of an interior permanent-magnet synchronous machine (IPMSM) with a single current sensor, used for low cost applications. The phase current, reconstructed from a dc-link current, shows a reconstruction error resulted from the difference of the sampling point from that of a full current sensor drive. This reconstruction error results in degradation of the overall sensorless control performance. In this paper, we analyze the impact of the reconstruction error depending on the injection frequency for a high frequency voltage signal injection sensorless control. Based on this analysis, we propose an improved position sensorless drive that employs a new current reconstruction method. In order to minimize the reconstruction error, the proposed current reconstruction method predicts the dq -axis currents with the same sampling point as a full current sensor drive. Several experimental results are provided to verify the analysis of the reconstruction error and the proposed method's improved sensorless control performances.

A Broadband, On-Chip Sensor Based on Hall Effect for Current Measurements in Smart Power Circuits

Abstract: This paper presents a broadband ([dc—megahertz (MHz)]) current sensor for power applications, which is based only on a Hall-effect probe as the core sensing element. Unlike common solutions for broadband current sensing, the proposed architecture is suitable for integration of the measurement system on the same low-cost CMOS chip used for the power electronics (e.g., Bipolar-CMOS-DMOS), without the need for external transformers and allowing for the realization of “smart power circuits.” The Hall-effect probe is biased by implementing the offset compensation-oriented spinning-current technique through a novel front-end, designed to push the operative bandwidth toward the fundamental limit of the probe. Specifically, the proposed front-end employs switches, which are typical of spinning-current techniques, only for biasing the Hall probe, while the readout process is performed by minimum-sized differential amplifiers. In this way, the capacitive load seen by the Hall probe is minimized and the sensor practical bandwidth upper limit is strongly increased. A prototype of the proposed architecture was operated at 8-MHz spinning frequency and characterized by means of standard figures of merit, demonstrating the broadband capability and an adequate overall performance. At the same time, the prototype revealed a new bandwidth limit, masked in conventional architectures by stronger capacitance-induced effects, which is represented by a degradation of the effectiveness of the spinning-current technique. Measured performance is comparable to that of standard, nonintegrated, current sensors, demonstrating the effectiveness of the presented purely Hall approach for broadband current sensing. The architecture was validated by discussing two case studies typical of power applications.

A New Phase Current Reconstruction Scheme for Four-Phase SRM Drives Using Improved Converter Topology Without Voltage Penalty

Abstract: Accurate current detection is of crucial importance for the operation and fault diagnosis of motor drives. In this paper, a new phase current reconstruction scheme is proposed for four-phase switched reluctance motors (SRMs) by using one dc-link current sensor without voltage penalty. First, an improved converter topology is proposed, which has fewer electronic components and a more compact structure compared with the conventional asymmetrical half-bridge converter. Then, an advanced pulse injection technology is developed to obtain the phase currents. By using the proposed approach, the cost and volume of the motor drive are reduced and the reliability of the system is improved. Most importantly, the scheme proposes a promising solution to the voltage penalty problem caused by the other existing strategies, which significantly increases the sampling accuracy without the restriction of the duty cycle of injected pulse. In order to verify the effectiveness of the proposed method, three classical control schemes including angular position control, current chopping control, and voltage pulse-width modulation control are all performed in the closed-loop system. The simulation and experiments based on a 150-W four-phase 8/6 SRM are carried out to validate the feasibility of this proposed scheme.

A Novel Open-Circuit Fault Diagnosis Method for Voltage Source Inverters With a Single Current Sensor

Abstract: For the purpose of reducing cost and volume, as well as to increase reliability in hostile environments, techniques of reconstructing three-phase current through a single current sensor have been reported for a three-phase alternating current motor vector control system. Based on the phase current reconstruction method, this paper proposes a novel open-circuit fault diagnosis method for the low-power voltage source inverter in the three-phase permanent-magnet synchronous motor drive. Other than sampling the single dc-link current sensor, the zero voltage vector sampling method (ZVVSM) is adopted to implement the fault diagnosis. By placing the single current sensor at a special position, ZVVSM is able to sample current during the two zero voltage vectors and reconstruct the three-phase currents. The reconstructed three-phase currents are used to generate the diagnostic variables that can detect and locate the faulty power switches. The PWM modulation strategy remains unchanged in this method and the reconstructed phase currents are with less waveform distortion and less harmonic contents, which are suitable for the fault diagnosis. The effectiveness of the proposed method is verified by experiments.

Improved dynamic performance of dual active bridge dc–dc converters using MPC scheme

Abstract: Dynamic performance is a key focus of power conversion systems for facing with input and output step-change and disturbance cases. To improve dynamic characteristic of dual-active-bridge dc-dc converters, this study proposes a non-linear model predictive control (MPC) scheme with phase-shift ratio compensation to face with the following extreme conditions: start-up or step change of load resistance, input voltage, and the desired output voltage. Furthermore, in view of the idea of direct current control, MPC scheme using fewer sensors is proposed, which greatly increases the flexibility of control system and reduce the cost. Compared to traditional voltage closed-loop (TVCL) control and model-based phase shift (MPS) control, the salient features of the proposed MPC can be summarised as excellent dynamic performance, weak parameter sensitiveness, in addition, it is also available and effective when the load current sensor is not used. Finally, three control schemes consisting of TVCL, MPS, and the proposed MPC scheme are compared and tested in a scale-down experimental prototype. The above excellent performance of the proposed MPC scheme has been verified by experimental results.

High-Frequency Voltage Injection Sensorless Control Technique for IPMSMs Fed by a Three-Phase Four-Switch Inverter With a Single Current Sensor

Abstract: This paper proposes a sensorless control strategy using sine-wave high-frequency (HF) voltage injection for interior permanent magnet synchronous motors (IPMSMs) fed by a three-phase four-switch (TPFS) inverter, with a single current sensor. Three-phase currents are reconstructed by a single current sensor with modification of the inverter topology. The principle of the phase current reconstruction strategy in TPFS inverter is analyzed and the topology of the proposed drive system is illustrated. Then, the normal areas and the dead zones for current reconstruction are investigated in detail, and the vector synthesis method is also explained. Furthermore, the zero vector synthesis strategy and the pulse width modulation (PWM) generation method are also presented, where two current sampling points are applied in each PWM cycle for phase current reconstruction. Finally, an HF voltage injection based sensorless control strategy in the proposed drive system is realized by voltage projection on the proposed k – l axis coordinate system. The reconstructed phase currents track the actual ones accurately, and the estimation error of the rotor position by using the reconstructed phase currents is within ±0.1 rad. The effectiveness of the proposed scheme is verified by simulation and experimental results on a 5-kW IPMSM prototype.

Phase Current Reconstruction and Control of Three-Phase Switched Reluctance Machine With Modular Power Converter Using Single DC-Link Current Sensor

Abstract: According to the modular power converter, a novel phase current reconstruction method using single dc-link current sensor is proposed for three-phase switched reluctance machine (SRM), and the control method is implemented with the reconstructed phase current as well. A highly integrated modular power converter is constructed by a three-phase full bridge and a dual switch module. The phase windings are in star-connection, and the bipolar phase currents are applied. Based on the special operating modes and single pulse width modulation signal injection, the dc-link current is decoupled and the phase current in both magnetization and demagnetization regions is reconstructed, which is very critical for the implementation of some advanced methods that require complete period phase current. The conventional control methods of the SRM, such as single-pulse voltage and hysteresis current control methods, are carried out under different operating conditions with both simulation and experiment to verify the effectiveness of the proposed method, and the reconstruction errors and performance influences are detailed analyzed as well.

Current Sensorless MTPA Operation of Interior PMSM Drives for Vehicular Applications

Abstract: This paper presents a direct voltage control method for interior permanent magnet synchronous motors (IPMSMs) with a single speed regulator. The method achieves maximum torque per ampere (MTPA) operation by controlling the magnitude and the angle of the voltage vector. For that, the mathematical model for the MTPA trajectory of the IPMSM is derived in the voltage plane. As such, no current sensor is needed, which makes the proposed strategy tolerant to current sensors failure unlike cascaded control loop based methodologies. Although no current sensor is used, the control strategy tracks MTPA trajectory by taking into account both voltage and current limits of the machine. The complete MTPA derivation in the voltage plane is presented in this paper; but, only the final solution is needed for real-time implementation. Henceforth, the simplicity of the control scheme combined with its current sensor dependence free characteristics make it a good candidate for real-time implementation in vehicular applications. The concept is developed and evaluated experimentally on a 10-HP IPMSM.

Leakage fault detection in Electro-Hydraulic Servo Systems using a nonlinear representation learning approach.

Abstract: Electro-Hydraulic Servo Systems (EHSS) are employed as actuators to track the desired trajectory and exert force in heavy-duty industrial applications. The EHSS is often prone to problems such as leakage and actuator seal damage during the course of its utilization. These faults which cannot be directly detected from current sensor values, can eventually result in complications and degrade control performance. The goal of this research is to use representation learning concepts to detect these faults with decreased complexity. The objective is to find a nonlinear mapping to transform raw data into another space in which classification becomes easier. The data are driven from the hydraulic supply pressure signal. To find the mapping, a custom-built optimization algorithm is proposed along with a suitable cost function to carry out the search for the new representation. The performance of the resulting transformation is tested in an experimental setting to show the merits of the proposed method.

Phase Current Sensor and Short-Circuit Detection based on Rogowski Coils Integrated on Gate Driver for 1.2 kV SiC MOSFET Half-Bridge Module

Abstract: Silicon-carbide (SiC) MOSFETs are enabling electrical vehicle motor drives to meet the demands of higher power density, efficiency, and lower system cost. Hence, this paper seeks to explore the benefits that a gate-driver-level intelligence can contribute to SiC-based power inverters. The intelligence is brought by PCB-embedded Rogowski switch-current sensors (RSCS) integrated on the gate driver of a 1.2 kV, 300 A SiC MOSFET half-bridge module. They collect two MOSFET switch currents in a manner of high magnitude, high bandwidth, and solid signal isolation. The switch-current signals are used for short-circuit detection under various fault impedances, as well as for phase-current reconstruction by subtracting one switch current from another. The fundamentals and noise-immunity design of the gate driver containing the RSCS are presented in the paper and can be applied to any half-bridge power module. A three-phase inverter prototype has been built and operated in continuous PWM mode. On this setup, the performance and limitations of the short-circuit detection and phase-current reconstruction are experimentally validated by comparing with commercial current probes and Hall sensors.

Magnetoresistor with Planar Magnetic Concentrator as Wideband Contactless Current Sensor for Power Electronics Applications

Abstract: High-frequency power electronic converters require lossless, accurate, and isolated current measurement. High-frequency currents through a printed circuit board (PCB) trace generate nonuniform magnetic field around the trace. The nonuniform magnetic fields can be normalized by means of magnetic field concentrators (MCONs) using conductive materials. In this study, a novel technique for high-frequency contactless current sensing using magnetoresistor (MR) sensors with planar magnetic concentrators (MCON) utilizing conductive materials has been proposed. The effect of different MCONs on the performance of anisotropic MR (AMR) sensors for high-frequency contactless current detection has been investigated. The performance of the AMR sensor equipped with different MCONs is demonstrated experimentally with respect to a fast rise step current. A detailed frequency analysis is performed on the sensor response with different MCONs to determine the effect on the detection bandwidth of the current sensors.

Fiber-Optic Current Sensor Tolerant to Imperfections of Polarization-Maintaining Fiber Connectors

Abstract: We investigate the effect of polarization cross-coupling at polarization-maintaining (PM) fiber connectors on the accuracy of an interferometric fiber-optic current sensor. The sensor uses the Faraday effect in a fiber coil operated in reflection mode and an interrogator based on nonreciprocal phase modulation. PM connectors in the fiber link between the sensor's opto-electronic module and the fiber coil give rise to signal instability due to a limited and insufficiently stable polarization extinction ratio (typically <;25-30 dB). As a result the accuracy of the sensor can be well outside the allowed tolerances of applications in the electric power industry which often demands accuracy to within ±0.2%. We demonstrate that by means of a modified optical circuit the disturbing effects of polarization cross-coupling can be largely eliminated. The modified circuit introduces group delays for the cross-coupled light waves relative to the undisturbed waves much larger than the coherence length of the broadband light source. We theoretically and experimentally show that connector extinction ratios well below 20 dB are still uncritical. Furthermore, we verify the superiority of the modified circuit at changing connector temperature (and hence changing temperature-induced stress in the connector ferrules) and at repeated connector open-close operations.

A Novel Virtual Sensing With Artificial Neural Network and K-Means Clustering for IGBT Current Measuring

Abstract: A novel virutal sensing (VS) method with artificial neural network (ANN) and K-means clustering for insulated-gate bipolar transistor (IGBT) current measuring is first proposed in this paper. It provides an alternative way to measure the IGBT current indirectly without a physical current sensor. It satisfies the requirements of cost and integratability in some smart gate drive controlling. In this study, the IGBT analytical model is abstracted to an equivalent expression for the prediction of IGBT current. The machine-learning technologies, the ANN and K-means clustering, are implemented for solving this equivalent expression based on statistical data to work out the empirical VS model for IGBT current prediction. The simulations show that this method is effective and it conforms to the outputs of pure analytical calculation from IGBT PSpice model. The experimental platform is also built to qualify the feasibility and practicability of this method, and it results 3% error by average in IGBT global current prediction.

Linear ADRC direct current control of grid-connected inverter with LCL filter for both active damping and grid voltage induced current distortion suppression

Abstract: The conversion and utilisation of renewable energy generations often require grid-connected inverters. When applying LCL filter to remove power electronic chopping harmonics, the power quality faces two issues of resonance damping and grid voltage induced current distortion. Conventionally, two separate control algorithms are required to treat the two issues, requiring an additional current sensor, increasing control complexity and limiting performance. This study demonstrates that linear active disturbance rejection control (ADRC) is able to treat both resonance damping and grid voltage induced current distortion as overall disturbance at the same time through a single structure, while achieving higher power quality for dynamic, steady-state, small and large parameter setup, as well as parameter variations, as validated by experimental results. In principle, the ADRC can be configured with or without knowledge of the system model. This study also reveals that it is the measurement noise tolerance that makes the two configurations different in practice. By using model information in ADRC algorithm, the required bandwidth can be reduced, offering more tolerance to measurement noise. Moreover, the ADRC controller has only two parameters to tune for ‘fast’ or ‘slow’, which makes it easy for implementation.

A High-Speed Gate Driver with PCB-Embedded Rogowski Switch-Current Sensor for a 10 kV, 240 A, SiC MOSFET Module

Abstract: High-voltage SiC MOSFET modules are revolutionizing modern high power electronics owing to their high blocking voltage, low conduction resistance, and fast switching frequency. A 10 kV, 240 A SiC MOSFET module has recently become a candidate to build medium-voltage converters. The MOSFET module comprises three independent submodules that can be configured as three phase-legs, or one half-bridge by paralleling. To maximize its performance, this paper presents a smart gate driver design for this particular semiconductor device. The design concentrates on a high-current booster stage and a high-bandwidth PCB-embedded Rogowski switch-current sensors for the paralleled submodules. The PCB layout has satisfied high-voltage clearance and creepage standards. Finally, the booster current sharing and RSCS performance have been experimentally validated.

Coupled-Inductor-Based DC Current Measurement Technique for Transformerless Grid-Tied Inverters

Abstract: Grid-tied photovoltaic inverters must fulfill several requirements, including high efficiency and reduced cost and complexity of the overall system. Hence, transformerless operation is advantageous in order to achieve the prior requirements. Meanwhile, such operation results in several demerits, such as the dc current component injection into the grid. This component should be effectively mitigated in order to avoid some impacts, such as the saturation of the transformers in the distribution network. On the other hand, limiting this component up to few milliamperes is a challenging issue due to the various measurement errors. Accordingly, different blocking and measurement techniques have been proposed and studied to overcome this issue, where some demerits are seen behind each technique such as the implementation complexity, the common-mode voltage problems, and the high filter requirements. Moreover, none of them measures the dc component directly, but predicts its value using different approaches. Hence, this letter proposes a new technique to measure this dc current component with high accuracy using a coupled inductor combined with a small-range Hall effect current sensor in order to achieve the lowest possible cost with the highest possible accuracy. The proposed technique is introduced, analyzed, and tested experimentally to verify its principle of operation. Also experimental measurement of the dc current component using a 5-kVA transformerless grid-tied voltage-source inverter is introduced with and without the proposed technique in order to validate its operation.

An LQR-Based Controller Design for an LCL-Filtered Grid-Connected Inverter in Discrete-Time State-Space under Distorted Grid Environment

Abstract: In order to alleviate the negative impacts of harmonically distorted grid conditions on inverters, this paper presents a linear quadratic regulator (LQR)-based current control design for an inductive-capacitive-inductive (LCL)-filtered grid-connected inverter. The proposed control scheme is constructed based on the internal model (IM) principle in which a full-state feedback controller is used for the purpose of stabilization and the integral terms as well as resonant terms are augmented into a control structure for the reference tracking and harmonic compensation, respectively. Additionally, the proposed scheme is implemented in the synchronous reference frame (SRF) to take advantage of the simultaneous compensation for both the negative and positive sequence harmonics by one resonant term. Since this leads to the decrease of necessary resonant terms by half, the computation effort of the controller can be reduced. With regard to the full-state feedback control approach for the LCL-filtered grid connected inverter, additional sensing devices are normally required to measure all of the system state variables. However, this causes a complexity in hardware and high implementation cost for measurement devices. To overcome this challenge, this paper presents a discrete-time current full-state observer that uses only the information from the control input, grid-side current sensor, and grid voltage sensor to estimate all of the system state variables with a high precision. Finally, an optimal linear quadratic control approach is introduced for the purpose of choosing optimal feedback gains, systematically, for both the controller and full-state observer. The simulation and experimental results are presented to prove the effectiveness and validity of the proposed control scheme.

The Influence of Interference Sources on a Magnetic Field-Based Current Sensor for Multiconductor Measurement

Abstract: Magnetic sensor arrays have been widely regarded as the practical implementations of current transducers, due to their ability to meet the demands for low power consumption and high accuracy in a wide frequency range. However, when used to reconstruct the currents flowing in the massive parallel conductors, e.g., a three-phase system, the setup still proves to be susceptible to the effects of external magnetic fields. In an effort to improve the immunity of this method, a differential array of magnetic field sensors is investigated. In this differential approach, the Moore–Penrose inversion method (least square inversion method) is used to obtain the set of currents at different positions inside the sensor from the measurement of the radial difference of the magnetic fields. The measurements, which were conducted in this paper, show that the differential array has a reduced crosstalk error when compared with a usual single-annular array of the same size and thus shown an improved immunity to the external magnetic fields by a factor of three and better.

Solar Energy Measurement Using Arduino

Abstract: This project aims to develop a measurement of solar energy using Arduino Board technology. In this research, four parameters that been measured are temperature, light intensity, voltage and current. The temperature was measured using temperature sensor. The light intensity was measured using light dependent resistor (LDR) sensor. The voltage was measured using the voltage divider because the voltage generated by the solar panel are large for the Arduino as receiver. Lastly for the current was measured using the current sensor module that can sense the current generated by the solar panel. These parameters as the input value for the Arduino and the output was display at the Liquid Crystal Display (LCD) screen. The LCD screen display output of the temperature, the light intensity, the voltage and the current value. The purpose of Arduino to convert the analog input of parameter to the digital output and display via LCD screen. Other than that, this project also involve with a design to ensure that device case are easy to be carry around.

A Novel DC Current Injection Suppression Method for Three-Phase Grid-Connected Inverter Without the Isolation Transformer

Abstract: Due to current sensor errors, tolerance of power switching devices, and asymmetry of PWM gating driving pulses, grid-connected inverters without isolation transformer usually have certain amount of dc components injected to the ac grid. Many efforts, such as using a blocking capacitor, a current dc component feedback control, and a voltage dc component feedback control have been introduced to try to suppress the dc injection to the grid. This paper proposes a novel control strategy of suppressing dc current injection to the grid for a three-phase inverter by accurately sensing the dc component of line voltages of three-phase inverter and adding a dc component control loop. A dc suppression control scheme is presented, and the suppression performance of the proposed dc rejection method is evaluated and compared with the traditional method. Finally, the control scheme is verified on a 20-kW three-phase grid-connected inverter.

Development of chipless, wireless current sensor system based on giant magnetoimpedance magnetic sensor and surface acoustic wave transponder

Abstract: A chipless, wireless current sensor system was developed using a giant magnetoimpedance (GMI) magnetic sensor and one-port surface acoustic wave (SAW) reflective delay line for real-time power monitoring in a current-carrying conductor. The GMI sensor has a high-quality crystalline structure in each layer, which contributes to a high sensitivity and good linearity in a magnetic field of 3–16 Oe. A 400 MHz RF energy generated from the interdigital transducer (IDT)-type reflector on the one-port SAW delay line was used as an activation source for the GMI magnetic sensor. The one-port SAW delay line replaces the presently existing transceiver system, which is composed of thousands of transistors, thus enabling chipless and wireless operation. We confirmed a large variation in the amplitude of the SAW reflection peak with a change in the impedance of the GMI sensor caused by the current flow through the conductor. Good linearity and sensitivity of ~0.691 dB/A were observed for currents in the range 1–12 A. Coupling of Mode (COM) modeling and impedance matching analysis were also performed to predict the device performance in advance and these were compared with the experimental results.

Monitoring System for Solar Panel Using Smartphone Based on Microcontroller

Abstract: Real time monitoring systems in photovoltaic (PV) power generation are very important and urgent in some cases. This paper proposes a real time monitoring system for solar panel using the Atmega 2560 arduino which is connected with voltage sensor, current sensor and temperature sensor. The Arduino ATMega 2560 also connects with the Wifi module as a connection to the smartphone to display the measurements of current, voltage and power of solar panel and ambient temperatures through the Blynk app. This system is tested for seven days starting at 08.00 am to 04.00 pm. The designed monitoring system has a good degree of accuracy with an average error rate of monitoring results of solar panel output value below 10%. Monitoring the performance of solar panels using a smartphone-based microcontroller can be done in real time. The monitoring system can be developed for the larger PV systems.

Stand-Alone Data Logger for Solar Panel Energy System with RTC and SD Card

Abstract: In this research stand-alone data logger device that can be used for measuring solar panel power characteristics is introduced. With RTC and SD Card installed on the device, the energy produced by solar panel is measured, then data are stored in CSV format that is compatible with MS Excel. Stand-alone feature makes it suitable for monitoring solar panel systems installed on remote area. Research result exhibits that all device sub systems are working perfectly. Voltage sensor convert the output voltage range of solar panel 0-24V to suitable voltage for microcontroller 0-5V. Real Time Clock (RTC) is able to show real time hours, minute and seconds of every measurements. Current sensor could measure the current with similar result compared to standard lab instruments. Despite data stored to SD Card, a 16&2 LCD display real time measurement results. Overall, the device works very well as if standard data logger instrument, but featuring real time monitoring and computer compatibility data.

Investigation of the Active Ripple Compensation Technique to Reduce Bulk Capacitance in Offline Flyback-Based LED Drivers

Abstract: This paper presents the study of an offline flyback-based light-emitting diode (LED) driver with reduced storage capacitance. An approach called active ripple compensation was used for minimizing the converter bulk capacitance. This technique is oriented to voltage-controlled pulse width modulation converters and is based on the modulation of the duty cycle, which allows for the reduction of the filtering capacitance by increasing the harmonic content of the input current up to the limits established by the standards. By means of the design procedure presented in this paper, the amount of capacitance reduction and input current distortion can be fully controlled and theoretically predicted. In addition, no extra sensors are required to implement the proposed technique, apart from the LED current sensor already available in most LED drivers. Experimental results from a 50-W laboratory prototype supplied from a 220-V 60-Hz grid were carried out. The results were compared with the conventional approach, attesting the superior performance of the proposed methodology.

Noninvasive Current Sensor for Multicore Cables

Abstract: Multicore cables are widely used in medium- and low-voltage electric power systems. Current measurement of individual conductors in such cables is especially useful for various advanced applications but technically difficult to implement. Since existing current sensing devices are designed for a single conductor, one has to break the cable enclosure or connector to access individual conductors for current measurement, which is practically infeasible. A noninvasive current sensor for multicore cables is proposed, designed, implemented, and verified in this paper. It is able to measure the magnetic field outside the cable using a sensor array and reversely calculate the currents on individual conductors. It is easy to install and adapt multiple cable specifications. Such a device is able to determine current phasors, perform harmonic analysis, and detect current disturbance with sufficient accuracy. The effectiveness of the proposed approach is validated by both laboratory experiment and field test.