Showing papers on "Current sensor published in 2017"

A Robust Observer-Based Method for IGBTs and Current Sensors Fault Diagnosis in Voltage-Source Inverters of PMSM Drives

Abstract: Permanent magnet synchronous motors (PMSMs) drives using three-phase voltage-source inverters (VSIs) are currently used in many industrial applications. The reliability of VSIs is one of the most important factors to improve the reliability and availability levels of the drive. Accordingly, this paper presents a robust fault diagnostic method for multiple insulated gate bipolar transistors (IGBTs) open-circuit faults and current sensor faults in three-phase PMSM drives. The proposed observer-based algorithm relies on an adaptive threshold for fault diagnosis. Current sensor and open-circuit faults can be distinguished and the faulty sensors and/or power semiconductors are effectively isolated. The proposed technique is robust to machine parameters and load variations. Several simulation and experimental results using a vector-controlled PMSM drive are presented, showing the diagnostic algorithm robustness against false alarms and its effectiveness in both IGBTs and current sensors fault diagnosis.

Single Sensor-Based MPPT of Partially Shaded PV System for Battery Charging by Using Cauchy and Gaussian Sine Cosine Optimization

Abstract: This paper introduces a battery charging scheme from a solar photovoltaic (SPV) by using a single sensor-based maximum power point tracking (MPPT) strategy. Here, for quick and efficient tracking, a novel hybrid “Cauchy and Gaussian sine cosine optimization” (CGSCO) algorithm is proposed for MPPT, which is based on only a single current sensor. The main objective of the CGSCO algorithm is, maximum extraction of the power from SPV panel and efficiently charging the battery through maximizing the charging current of the battery. Due to the single sensor, the cost of the charging scheme is very low, as well as the algorithm complexity and computational burden are very less, so it can be easily implemented on the low-cost microcontroller. In this paper, a single current sensor-based battery charging scheme by CGSCO algorithm is tested on MATLAB simulator and verified on a developed hardware of the SPV system. The panel condition, with and without shaded as well as dynamic environmental condition (variable temperature and insolation), is considered during simulation as well as on hardware implementation. Moreover, the tracking ability is compared with the most recent state of the art techniques (Grey wolf optimization and Lagrange interpolation particle swarm optimization (LIPSO)) as well as compared with “CGSCO with the conventional dual (voltage and current) sensor-based MPPT scheme.” The efficient battery charging with quick MPPT by CGSCO algorithm w.r.t. all state of the art techniques as well as dual sensor-based MPPT scheme, in steady-state as well as in dynamic conditions meets the motive of the work.

Open-Circuit IGBT Fault Detection and Location Isolation for Cascaded Multilevel Converters

Abstract: An open-circuit insulated-gate bipolar transistor fault detection technique for cascaded H-bridge (CHB) multilevel converters is presented in this paper. This technique, designed to be implemented independently for each CHB leg, utilizes one current sensor and one voltage sensor to monitor a leg's current and output voltage. Measured voltages are compared to expected voltages, and deviations are used to determine open-circuit fault locations based on the deviation's magnitude and current flow direction. Once potential fault locations have been identified, the fault location is systematically isolated and then verified, reducing the possibility of unnecessary corrective actions due to fault misidentification, e.g., an intermittent gate-misfiring fault being classified as an open-circuit fault. The proposed technique can be implemented for any number of cells, is independent of the pulse width modulation strategy used, and can be applied to symmetric and asymmetric CHB converters regardless of the cell input dc-source magnitudes utilized, i.e., cell input voltages are not required to be equal or to exist in specific ratios. For a CHB leg with $M$ cells, the proposed technique identifies and isolates open-circuit switch faults in less than $2M$ measurement (sampling) cycles, and verification is completed in less than one full fundamental cycle. Experimentally obtained data demonstrate the efficacy of the proposed fault detection and isolation technique.

Zero Voltage Vector Sampling Method for PMSM Three-Phase Current Reconstruction Using Single Current Sensor

Abstract: For the purpose of reducing cost and volume, techniques of reconstructing three-phase currents through a single current sensor have been reported for permanent magnet synchronous motor vector control system. In existing studies, the reconstruction precision is largely affected by the dead zones in space vector PWM plane, which requires additional efforts to compensate the dead zones either by modifying pulse width modulation (PWM) modulation strategy or by phase-shifting of PWM signal. In this paper, a novel zero voltage vector sampling method (ZVVSM) is proposed, which can move the current reconstruction dead zones in low modulation region and sector boundary regions toward the outline of the space vector hexagon without modifying PWM signal. By arranging the single current sensor at a novel position, the proposed method is able to sample current in two zero voltage vectors (ZVV). ZVVSM avoids the complicated algorithms as well as the increase of the switching times, so that it is beneficial to the PMSM drive performance. The proposed method is validated by both simulation and experiments.

Current Sensor Fault-Tolerant Control for Direct Torque Control of Induction Motor Drive Using Flux-Linkage Observer

Abstract: This paper proposes a novel fault-tolerant control (FTC) scheme for direct torque control of induction motor (IM) drives against the line current sensor failures. Three major steps involved in the proposed FTC scheme are the detection of sensor fault, isolation of the same, and finally, the reconfiguration by proper estimation. Third-difference operator employed in the motor line current is found suitable for the detection of the sensor fault, while flux-linkage observer-based current estimation scheme performs the task of estimation of line current post the occurrence of the fault. Furthermore, a decision-making logic circuitry isolates the faulty signal and simultaneously selects the appropriate estimated current signal to make the drive fault-tolerant. The proposed current sensor FTC scheme is simple and unique in nature. Moreover, it can be universally applied with any speed control schemes involving IM drive. The proposed scheme is simulated and extensively tested in MATLAB/Simulink. The obtained simulation results are also verified using a dSPACE-1104-based IM drive laboratory prototype to show the effectiveness of the scheme.

A Fast On-Line Diagnostic Method for Open-Circuit Switch Faults in SiC-MOSFET-Based T-Type Multilevel Inverters

Abstract: On-line condition monitoring is of paramount importance for multilevel power converters used in safety-critical applications. A novel on-line nonintrusive diagnostic method for detecting open-circuit switch faults in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs)-based T-type multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variations of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include faster detection speed and simpler implementation compared to other existing diagnostic methods in the literature. Moreover, this diagnostic method is immune to the disturbances of inverter's dc-bus voltage unbalance and load unbalance. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current; therefore, the implementation cost is low. Simulation and experimental results based on a lab-scale 20 kVA adjustable speed drive with a three-level SiC T-type inverter validate the effectiveness and robustness of this novel diagnostic method.

A Self-Healing Induction Motor Drive With Model Free Sensor Tampering and Sensor Fault Detection, Isolation, and Compensation

Abstract: This paper introduces new schemes for detection, isolation, and compensation of speed and current sensor (CS) faults in field oriented induction motor (IM) drives. These schemes do not use any kind of machine model and motor parameters. This is a prominent feature of the proposed approaches, which only rely on main concepts of field-oriented control (FOC)-based IM drives. Moreover, the proposed fault detection and isolation (FDI) schemes can take partial sensor failures into account. These kinds of faults that might be caused by mechanical or electrical failures, or intentional sensor tampering, are difficult to be dealt with since embedded speed and current control loops react swiftly, and inherently try to camouflage partial sensor failures. CS faults result in imbalance current flow in the motor stator phases, and speed sensor fault repudiates the orthogonally alignment of field and torque current components in field oriented IM drives. These features are cornerstones of introduced FDI methodology. Furthermore, model and parameter free compensators are proposed to recover normal operation of the machine before fault incident. After in-depth analysis, extensive simulation and experimental tests validate the proposed schemes.

An AMR-Based Three-Phase Current Sensor for Smart Grid Applications

Abstract: In a smart grid (SG) scenario, accurate and real-time information about key grid parameters (such as voltage and current in each node of the net) are strategic requirements. In order to grant the best tradeoff between the measurement accuracy and the economic sustainability of SG distributed measurements, the design and the development of suitable low-cost current/voltage sensors are required. To this aim, this paper proposes a three-phase contactless current sensor based on anisotropic magnetoresistance effect. A suitable sensors placement strategy is used to compensate the uncertainty due to the interfering magnetic fields (i.e., magnetic fields generated from other electrical apparatus near to the sensors or from the other wires of the three-phase system). After a preliminary characterization of the proposed solution in a simulated environment, an experimental validation is carried out and reported in this paper.

Bidirectional Single-Stage Grid-Connected Inverter for a Battery Energy Storage System

Abstract: The objective of this paper is to propose a bidirectional single-stage grid-connected inverter (BSG-inverter) for the battery energy storage system. The proposed BSG-inverter is composed of multiple bidirectional buck–boost type dc–dc converters (BBCs) and a dc–ac unfolder. Advantages of the proposed BSG-inverter include: single-stage power conversion, low battery and dc-bus voltages, pulsating charging/discharging currents, and individual power control for each battery module. Therefore, the equalization, lifetime extension, and capacity flexibility of the battery energy storage system can be achieved. Based on the developed equations, the power flow of the battery system can be controlled without the need of input current sensor. Also, with the interleaved operation between BBCs, the current ripple of the output inductor can be reduced too. The computer simulations and hardware experimental results are shown to verify the performance of the proposed BSG-inverter.

Magnetoelectric Current Sensors.

Abstract: In this work a magnetoelectric (ME) current sensor design based on a magnetoelectric effect is presented and discussed The resonant and non-resonant type of ME current sensors are considered Theoretical calculations of the ME current sensors by the equivalent circuit method were conducted The application of different sensors using the new effects, for example, the ME effect, is made possible with the development of new ME composites A large number of studies conducted in the field of new composites, allowed us to obtain a high magnetostrictive-piezoelectric laminate sensitivity An optimal ME structure composition was matched The characterization of a non-resonant current sensor showed that in the operation range to 5 A, the sensor had a sensitivity of 034 V/A, non-linearity less than 1% and for a resonant current sensor in the same operation range, the sensitivity was of 053 V/A, non-linearity less than 05%

Module-Integrated GMR-Based Current Sensing for Closed-Loop Control of a Motor Drive

Abstract: Current sensor integration in commercial power semiconductor modules is generally based on shunt resistance methods. The resulting losses and lack of galvanic isolation present opportunities for improvement. This paper describes the integration of submillimeter-sized giant magnetoresistive (GMR) point field detectors (PFDs) into commercial IGBT modules to provide nearly lossless galvanically isolated current-sensing capabilities. The IGBT modules are installed into a three-phase inverter motor drive, and the GMR-based integrated current sensors are used for closed-loop current control in a field-oriented induction motor drive. Finite-element analysis of the module interconnect structures is used to determine detector locations offering the highest possible bandwidth current measurements. Additional PFDs are used to decouple rotating magnetic field disturbances or bias fields from permanent magnets. The same GMR PFDs are also used to provide temperature measurements that are used to decouple the effects of changing temperature.

Current-Sensorless Power-Decoupling Phase-Shift Dual-Half-Bridge Converter for DC–AC Power Conversion Systems Without Electrolytic Capacitor

Abstract: In this paper, a novel DHB power-decoupling control scheme without current sensor is proposed for single-phase inverters. As electrolyte capacitors are conventionally used; however, these capacitors limit ripple current capability and circuit reliability. Film capacitors improve the ripple current capability, size reduction, and circuit reliability. Conventionally, non-isolated topologies are used for power decoupling. The volume of the decoupling capacitor per unit energy in isolated bidirectional power decoupling topologies is reduced as compared to nonisolated due to unrestricted voltage across the decoupling capacitor. Voltage-fed Phase-Shift Dual Half-Bridge (DHB) is preferred with film capacitors as it has the least number of components in isolated bidirectional topologies. However, in DHB, power decoupling controller is a challenge as current control is conventionally required. The challenge has been overcome with novel current-sensorless dc link ripple rejection control. The controller has the advantage of current-sensorless configuration especially when it needs information from inverter phase-lock-loop (PLL). The proposed power decoupling control scheme is independent of the inverter control and universal. A new dynamic analysis has been carried out by taking into account the input-voltage dynamics. The advantage of the DHB is that it has single pole behavior and, hence, sufficient bandwidth can be obtained. Simulations and experiments have been performed to verify the analysis of the power decoupling control scheme and the capability of film-capacitor DHB for power decoupling.

Low Complexity Motor Current Signature Analysis Using Sub-Nyquist Strategy With Reduced Data Length

Abstract: Motor current signature analysis requires high sampling rate and a large number of data samples to detect faults at light loading conditions. However, it would be interesting to investigate the alternative methods to bring down these requirements using the principle of sparse signal processing. In this paper, a low-complexity fault detection algorithm based on the sub-Nyquist sampling of the analytic current signal has been proposed and compared to other similar algorithms. The acquired current data is first converted into an analytic signal using a low-cost time-shift-based method. The processing of the analytic current signal has been performed at a rate 20 times lower than the Nyquist criterion using multicoset sampling technique. The computational complexity has been reduced further by partially reconstructing the spectrum only for the regions of interest. The regions of interest were found out from the estimated supply frequency and the armature current magnitude. The supply frequency has been estimated from the transformed analytic current signal. The algorithm has been tested for broken rotor bar (BRB), eccentricity, and broken bearing faults, using the recorded data from a 22-kW induction motor drive at various loading conditions in the laboratory. In addition, the BRB fault has also been tested for motors with 1.5- and 3.7-kW ratings. A receiver operating characteristic curve has been generated to test the performance of the algorithm. The proposed algorithm uses only a single current sensor to acquire one of the armature phase currents.

Robust Fault Detection, Isolation, and Accommodation of Current Sensors in Grid Side Converters

Abstract: The integration of modern renewable energy sources is enabled by the grid side converter (GSC) based on power electronic technology. The operation of the GSC is properly regulated by the GSC controller according to sensor measurements (i.e., of the grid voltage, of the line currents, and of the voltage at the dc-link). However, in case of current sensor faults, the operation of the GSC and of the entire renewable system can be critically affected and catastrophic failures may occur if the sensor fault is not accommodated on time. This paper proposes a model-based Fault Detection, Isolation, and Accommodation (FDIA) scheme, which enables the GSC to overcome faults that may occur on the associated current sensors. The sensor fault detection and isolation scheme has been designed based on analytical redundancy relations, while the accommodation of the faults is based on an adaptive estimation scheme. The proposed FDIA scheme has been applied on a modern GSC and the effectiveness of the scheme has been tested under several multiple current sensor faults and under several grid conditions. Furthermore, the FDIA scheme enables the GSC to operate properly (without causing failures or damages to its components) under current sensor faults and thus, the reliability of the GSC is enhanced.

Noninvasive Online Condition Monitoring of Output Capacitor’s ESR and C for a Flyback Converter

Abstract: Since electrolytic capacitors are primarily responsible for breakdowns in power electronics converters and have the trait of high failure rate, their reliability is a tremendous concern. Consequently, an appropriate monitoring as well as fault diagnosis system should be laid emphasis on. In this paper, an original and accurate online scheme applied to estimate the output capacitor of the flyback converter is put forward. By analyzing the voltage ripple of the output electrolytic capacitor in detail, an online mathematical model for the equivalent series resistance (ESR) and capacitance (C) is derived. A trigger circuit and an isolated amplification circuit are designed to catch the output voltage ripple values at certain instants of switching cycle, which are sent to digital signal processor for the calculation of ESR and C. The proposed scheme is noninvasive as no extra current sensor is needed. In order to verify the feasibility of the scheme, a prototype of the online monitoring system is built and experiments are conducted.

Implementation of a MFAC based position sensorless drive for high speed BLDC motors with nonideal back EMF.

Abstract: In order to improve the reliability and reduce power consumption of the high speed BLDC motor system, this paper presents a model free adaptive control (MFAC) based position sensorless drive with only a dc-link current sensor. The initial commutation points are obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. According to the commutation error caused by the low pass filter (LPF) and other factors, the relationship between commutation error angle and dc-link current is analyzed, a corresponding MFAC based control method is proposed, and the commutation error can be corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.

Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System.

Abstract: This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs) are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI). Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system.

Electronic Energy Meter Based on a Tunnel Magnetoresistive Effect (TMR) Current Sensor

Abstract: In the present work, the design and microfabrication of a tunneling magnetoresistance (TMR) electrical current sensor is presented. After its physical and electrical characterization, a wattmeter is developed to determine the active power delivered to a load from the AC 50/60 Hz mains line. Experimental results are shown up to 1000 W of power load. A relative uncertainty of less than 1.5% with resistive load and less than 1% with capacitive load was obtained. The described application is an example of how TMR sensing technology can play a relevant role in the management and control of electrical energy.

Temperature-Compensated Magnetostrictive Current Sensor Based on the Configuration of Dual Fiber Bragg Gratings

Abstract: For the optical current sensor that combines FBG and magnetostrictive material, a key problem is that the performance of FBG and magnetostrictive material is influenced by the operating temperature. In this paper, in order to overcome this problem, we proposed a method of temperature compensation based on the dual FBG configuration, which can make the measuring result of magnetic field be essentially temperature independent. In this method, two FBGs with the same type are bonded on two giant magnetostrictive materials, respectively. The two giant magnetostrictive materials have the identical shape and come from the same bulk material, while they have the orthogonal magnetostriction directions. We perform the experiment to investigate the performance of this method at different temperatures and at different magnetic fields, in order to verify the feasibility of this method. The experiment results demonstrate that this method significantly decreases the influence of temperature, and thus it can maintain a relative good performance in the temperature range of 20 °C–70 °C.

A Lithium-Ion Battery Current Estimation Technique Using an Unknown Input Observer

Abstract: Current consumption measurements are useful in a wide variety of applications, including power monitoring and fault detection within a lithium-ion battery management system (BMS). This measurement is typically taken using either a shunt resistor or a Hall-effect current sensor. Although both methods have achieved accurate current measurements, shunt resistors have inherent power loss and require isolation circuitry, and Hall-effect sensors are generally expensive. This paper explores a novel alternative to sensing battery current by measuring terminal voltages and cell temperatures and using an unknown input observer to estimate the battery current. An accurate model of a LiFePO4 cell is created, validated, and then used to characterize a model of the proposed current estimation technique. Finally, the current estimation technique is implemented in hardware and tested in an online BMS environment. Results show that the current estimation technique is sufficiently accurate for a variety of applications, including fault detection and power profiling.

Phase current reconstruction strategy for switched reluctance machines with fault-tolerant capability

Abstract: This study presents a novel phase current reconstruction strategy for switched reluctance machines (SRMs) using two cross-winding current sensors. The phase currents are reconstructed by solving the linear equations associated with two adjacent phase currents in the different turn-on regions. The effect of current sensor offset and power transistor fault on the proposed reconstruction method is analysed. On the basis of the current difference at the rising edge of each drive signal, an offset sensor identification method is presented and two online compensation schemes are adopted. For power transistor short-circuit fault, the logic-judgment-based and freewheeling-time-based diagnostic methods are investigated and a virtual current sensor is introduced to ensure the effectiveness of the reconstruction process. The proposed phase current reconstruction strategy is free from power transistor open-circuit fault. In addition, the current reconstruction method is easily extended to SRMs with higher number of phases without additional current sensors. Simulations and experiments validate the effectiveness and flexibility of the proposed reconstruction strategy.

Current sensorless predictive control based on extended kalman filter for pmsm drives

Abstract: This paper proposes a novel current sensorless drive system with only position sensor for permanent magnet synchronous motor drive in order to reduce costs and avoid problems caused by faults of the current sensor. Generally a pmsm drive controller needs at least two phase-current sensors, in this paper, the current sensors is omitted by replacing estimated stator current with extended kalman filter. A simulation study is performed in order to compare performances with and without current sensor, it shows that the control has almost the same performance and ability as the conventional control.

Enhanced sensitivity of temperature-compensated SAW-based current sensor using the magnetostrictive effect

Abstract: A temperature-compensated surface acoustic wave (SAW)-based current sensor was proposed in this contribution, composed of a sensor chip made by SAW delay line patterns on a SiO2/128° YX LiNbO3 piezoelectric substrate, a magnetostrictive FeCo film deposited on the SAW propagation path, and a corresponding differential oscillation configuration. The FeCo coating produced magnetostrictive strain under the magnetic field generated by the applied current, leading to linearity changes in the SAW propagation in the form of velocity change. The corresponding differential oscillation frequency shift was used to evaluate the tested current. By solving the coupled electromechanical field equation in a layered structure while considering the magnetostrictive effect, the optimal FeCo film thickness, and sensor operation frequency yielding high current sensitivity, were determined, and then confirmed experimentally by evaluating the developed SAW current sensor system utilizing a Helmholtz coil. A high sensitivity of 16.6 KHz A−1 (8.3 KHz m−1 T−1), excellent linearity, and lower detection limit (~0.2 mA) were achieved with our 300 MHz SAW sensor with a 500 nm FeCo coating and aspect ratio of 2:1.

Reducing N2O induced cross-talk in a NDIR CO2 gas sensor for breath analysis using multilayer thin film optical interference coatings

Abstract: Carbon dioxide (CO 2 ) gas sensing is an important aspect in the biomedical field of capnography, where cheap, fast and accurate measurement of exhaled CO 2 vs. time is crucial in the evaluation of lung and tracheal function during surgical anaesthesia and is an under-used bio-marker for underlying respiratory conditions. Current detection methods do not adequately meet these requirements and suffer from considerable cross-talk associated with the commonly used anaesthetic gas nitrous oxide (N 2 O). In this work, we report how cross-talk can be reduced in a commercially available, low power (35 mW) non-dispersive infrared (NDIR) CO 2 gas sensor using thin film multilayer optical filters. Current sensor spectral response, spans 2500 nm–5000 nm via use of a pentanary alloy LED/photodiode optopair grown by molecular beam epitaxy (MBE), resulting in sensor sensitivity to gases with absorption bands in this region, including N 2 O. To reduce the effective spectral response of the sensor, capturing only CO 2 , a multilayer thin film optical interference bandpass filter has been designed and deposited directly onto the diode epi-structures using microwave plasma assisted DC magnetron sputtering. Three different coating configurations have been explored; LED-only coated, photodiode only coated and both coated. Gas sensor response to N 2 O for each coating configuration has been explored. It was found that application of an optical bandpass filter onto both the sensor LED and photodiode only was the most effective method of reducing sensor response to N 2 O, however no signal was observed in one of the two “LED and PD coated”, therefore optimal coating configuration for cross-talk reduction is subject to further investigation.

Detection and Estimation of Extremely Small Fault Signature by Utilizing Multiple Current Sensor Signals in Electric Machines

Abstract: This paper presents a novel motor current signature analysis algorithm for accurate detection and precise estimation of extremely small fault signature by utilizing multiple–phase-current signals in an electric machine. The two most critical challenges in developing a reliable diagnosis method are the detection of extreme small signals under extremely harsh environment, and the formulation of adaptive threshold under dynamic operation and noise variation of a motor. These challenges are addressed in this paper by logically and statistically utilizing multiple existing current sensors and current signals to make an accurate detection, and statistical/adaptive threshold for precise detection and decision making. The performance of the proposed algorithm has been mathematically and theoretically proved under modeled Gaussian noise conditions. Proposed theory is also experimentally verified on a 3-kW five-phase permanent-magnet-assisted synchronous reluctance motor.

Passive MEMS DC Electric Current Sensor: Part II–Experimental Verifications

Abstract: This paper, the second part of two companion papers, reports experimental methodology and verification results based on the prototype device of the proposed passive MEMS dc current sensor in Part I. The relationship between output voltages and crucial factors, such as the relative position of the sensor to the two-wire appliance cord, different connection modes of the PZT partition plates, as well as the applied dc current has been characterized. The experimental methodology mainly includes those of how to position the sensor device, how to determine the measurement range for sensitivity characterization, and how to electrically connect the PZT partition plates in different modes. Sensitivity characteristics were studied in ac current from 8 to 400 mA and in dc current from 0.5 to 3 A, respectively. Two typical connection modes, i.e., in series and parallel, were investigated with ten PZT partition plates. In the case of dc current, the waveforms of the output voltage in the individual PZT plate were studied in detail. First, the initial peak voltages corresponding to ON–OFF switching of dc current can be clearly characterized with a higher amplitude (relatively lower frequency) for turning ON and a lower one (relatively higher frequency) for turning OFF. Second, the measured peak voltages are smaller than the analytical ones, but showing similar increasing tendency with the increasing of the dc current. In light of the above-mentioned experimental verifications, the proposed passive MEMS dc current sensor was proved to be applicable to direct measurements of the two-wire appliance cords without using cord separator. The proposed sensor devices are, therefore, more convenient than Hall-effect-based sensors in electricity end-use measuring and monitoring of dc power supply.

A 100 MHz Hybrid Supply Modulator With Ripple-Current-Based PWM Control

Abstract: This paper presents a 100 MHz hybrid supply modulator (HSM) with ripple-current-based pulse width modulation (PWM) control. By sensing the ripple current, a ripple current sensor (RCS) is able to overcome the bandwidth limitation of an absolute current sensor. By leveraging the RCS, we propose a large-signal PWM control method for HSMs. This method has an intrinsically fast switching loop, and thus eliminates the need for the feed-forward path used in many previous designs. The possibility of generating high-order harmonics in PWM-controlled HSMs is pointed out for the first time, and design recommendations to avoid them are presented. A very-high-frequency triangular wave generator that is robust to both process-voltage-temperature (PVT) variations and device mismatches is proposed. A proof-of-concept prototype was fabricated in CMOS 130 nm technology. Switching at 100 MHz, this HSM is able to track a 0.8 $V_{\mathrm {\mathbf {pp}}}$ sinusoidal waveform up to 13 MHz with high fidelity. It achieves a peak efficiency of 88.2% at the maximum output power of 23 dBm. To the best of our knowledge, this is the first PWM-controlled HSM that is able to operate at 100 MHz.

A Calibration Setup for IEC 61850-9-2 Devices

Abstract: The working principle and the architecture of a calibration system for devices operating with the IEC 61850-9-2 standard are described. Two different types of devices are considered: stand-alone merging units (SAMUs) used to retrofit conventional transformers in power network substations and commercial test sets suited for nonconventional voltage and current sensor calibration in the field. An SAMU is essentially an analog-to-digital converter delivering its results in the IEC 61850-9-2 format. The functionalities of the test set evaluated here are the analog signal generation (voltage and current) and their synchronous IEC 61850-9-2 representation. This paper presents a calibration setup that has been applied to both types of devices.

Current limiting soft starter for three phase induction motor drive system using PWM AC chopper

Abstract: This study presents a new current-limiting soft-starter for a three-phase induction motor drive system using pulse width modulation (PWM) AC chopper. A novel configuration of three-phase PWM AC chopper using only four insulated gate bipolar transistors (IGBTs) is also proposed. The proposed control strategy does not require zero crossing detection circuits, which employed in thyristorised soft starters. It requires only one current sensor. The duty ratio of the chopper IGBTs is obtained from the closed-loop current control in order to limit the motor starting current at a preset value. Only two complementary gate pulses are obtained from the control circuit to control the four IGBT switches. The proposed control strategy is characterised by a simple control loop; thus, a low-cost processor can be used due to the low-computation burden. The superiority of the proposed strategy is proved theoretically and confirmed experimentally. The experimental work is developed using a laboratory prototype system composed of DSP-DS1104 digital control board and 1.5 HP induction motor. The proposed starter offers a smooth start-up for the motor speed, torque ripple minimisation, less number of semiconductor switches, less switching and conduction losses, less harmonics and improved input power factor.