Showing papers on "Current sensor published in 2021"

Load Current and State-of-Charge Coestimation for Current Sensor-Free Lithium-Ion Battery

Abstract: The installation of current sensors on lithium-ion batteries (LIBs) can be challenging due to practical constraints in specific applications like portable electronics and smart batteries. Motivated by this, our letter proposes a method for online load current and state-of-charge (SOC) coestimation, which mitigates the need of installing the current sensor for LIB management. The essence is to transform the state observation into a constrained optimization problem, which is solved numerically in a moving horizon framework to allow the online coestimation of SOC and input current. Experimental results suggest that the proposed method can coestimate the load current and SOC of LIB precisely even if the current sensor is absent. The encouraging results are insightful for reducing the structural complexity and cost of future LIB utilization.

Improved DC-Link Voltage Regulation Strategy for Grid-Connected Converters

Abstract: In this article, an improved dc-link voltage regulation strategy is proposed for grid-connected converters applied in dc microgrids. For the inner loop of the grid-connected converter, a voltage modulated direct power control is employed to obtain two second-order linear time-invariant systems, which guarantees that the closed-loop system is globally exponentially stable. For the outer loop, a sliding mode control strategy with a load current sensor is employed to maintain a constant dc-link voltage even in the presence of constant power loads at the dc-side, which adversely affect the system stability. Furthermore, an observer for the dc-link current is designed to remove the dc current sensor at the same time improving the reliability and decreasing the cost. From both simulation and experimental results obtained from a 15-kVA prototype setup, the proposed method is demonstrated to improve the transient performance of the system and has robustness properties to handle parameter mismatches compared with the input–output linearization method.

New Three-Phase Current Reconstruction for PMSM Drive With Hybrid Space Vector Pulsewidth Modulation Technique

Abstract: Current sensing techniques with reduced number of sensors attract a high interest from industry, for the possibility of cost reduction and sampling mismatch reduction. This article puts forward a new single current sensor (SCS) method for a permanent magnet synchronous motor three-phase current reconstruction, with a novel hybrid pulsewidth modulation (PWM) technique introduced. This method is implemented by changing the position of SCS from dc bus to a current branch, and a modified space vector PWM technique is employed to realize the phase current reconstruction. Compared with traditional SCS control methods, the proposed method can relieve the measurement dead-zones at sector boundary region without introducing extra compensation algorithms. Besides, this method can be realized not only with a single hall-effect current sensor but also a single shunt resistor, which further expands the applications and increases the system reliability as well. This method is also available in other motor control with a two-level three-phase PWM voltage source inverter topology. The accuracy and feasibility of the proposed method is validated by the simulation and experimental results.

A Fault Diagnosis Method for Current Sensors of Primary Permanent-Magnet Linear Motor Drives

Abstract: In this article, a fault diagnosis method is proposed to detect current sensor faults for the studied primary permanent-magnet linear motor (PPMLM) traction system, in which only two current sensors are required, and the gain fault and zero-offset fault can be distinguished. In this proposed fault diagnosis method, synchronous currents are estimated by the PPMLM model. By comparing the estimated and measured synchronous currents, estimation errors are calculated, and ac components can be extracted by corresponding filters. In the synchronous frame, the zero-offset fault and the gain fault can be detected by the single-frequency and double-frequency components, respectively. Furthermore, the fault phase also can be located. Compared with conventional fault diagnosis methods, the proposed one can distinguish gain fault and zero-offset fault but only two current sensors are required. Simulation and experimental results verify the effectiveness of the proposed fault diagnosis method.

Adaptive Hysteresis Current Based ZVS Modulation and Voltage Gain Compensation for High-Frequency Three-Phase Converters

Abstract: This article proposed a systematic approach for the control of three-phase bidirectional zero-voltage switching (ZVS) converters. Combining the adaptive hysteresis-band current control and turn- on delay modifications, ZVS conditions are realized in full line-cycle in all loading conditions like active power, reactive power, light load, and heavy load. The soft-switching resonant period is carefully analyzed, and the current band is designed accordingly, which minimized the additional conduction loss. Meanwhile, a zero-sequence voltage injection control is included in the approach, which compensates the voltage gain by 15% and narrows down the switching frequency variation range. The hardware design approach is also provided including the LCL filter design and a low-cost high-bandwidth high-accuracy current sensor design. A highly integrated 5-kW silicon carbide implemented three-phase ZVS converter prototype with printed circuit board integrated inductors and customized current sensors is designed. All the control is implemented in a single microcontroller unit, which achieves a high electromagnetic compatibility. The designed prototype achieves a total power density of 5.5 kW/L and a peak efficiency of 98.5%. All the analysis and the proposed control approach are experimentally verified on the designed prototype.

High-Bandwidth Low-Inductance Current Shunt for Wide-Bandgap Devices Dynamic Characterization

Abstract: High bandwidth sensors are required to measure the wide-bandgap devices’ transient behavior because of their fast switching speed. In addition to high bandwidth, the current sensor must introduce little extra parasitic inductance to the switching power loop. The analysis of conventional shunt resistors shows the key to high bandwidth is the coaxial structure and its parasitic inductance is proportional to its transient heat energy rating. By combining the structure of coaxial shunt resistor and alumina substrate surface mount thin film resistors, a novel surface mount coaxial shunt resistor is introduced. Experimental measurement verifies its capability of achieving very high bandwidth while introducing very low parasitic inductance. The design can achieve up to 2.23-GHz measurement bandwidth while keeping its parasitic inductance as low as 0.12 nH. Application in gallium nitride heterojunction-field-effect-transistors double pulse test shows it can faithfully capture the transient current waveform while introducing little interference to the switching behavior.

A Fast Finite-Level-State Model Predictive Control Strategy for Sensorless Modular Multilevel Converter

Abstract: In this article, we propose a fast finite-level-state model predictive control (FFLS-MPC) strategy for solving the well-known challenges in the predictive control-regulated modular multilevel converter (MMC), which aims to overcome the high computational complexity and enhance the reliability of the control system. First, the presentable output voltage level is determined from solving the Diophantine equations’ point of view, which has a good potential to avoid the online optimization process and the selection of weighting factors compared with the conventional finite control-set model predictive control (FCS-MPC) approach. In this sense, the overall computational effort is significantly decreased while achieving satisfactory control performance. Alternatively, in order to enhance the system reliability under sensor failures (e.g., arm current sensor and submodule (SM) voltage sensor), a novel control strategy for sensorless MMC is presented by combining an adaptive linear-neuron-based SM voltage estimation scheme with a currentless sorting-based capacitor-voltage-balancing approach to serve this purpose. We contribute two main points to the relevant literature. The first one is the improvement of computationally efficient by employing the proposed FFLS-MPC methodology. The second one is the elimination of the arm current sensor and SM voltage sensor while guaranteeing adaptability to different conditions. Finally, compared with the state-of-the-art FCS-MPC strategies, comprehensive simulation studies and experiments are presented to demonstrate the effectiveness and feasibility of the proposed methodology for MMC.

Capacitor Voltage Full Feedback Scheme for LCL -Type Grid-Connected Inverter to Suppress Current Distortion Due to Grid Voltage Harmonics

Abstract: For the LCL -type grid-connected inverter, grid voltage full feedforward scheme is an effective method to improve the quality of the injected grid current. However, in the applications where a step-up transformer is adopted and its leakage inductance serves as the grid-side inductor, it is difficult to directly measure the grid voltage. For this case, the capacitor voltage full feedback scheme is proposed in this article to suppress the injected grid current distortion due to the grid voltage harmonics, and the full feedback function includes proportional, derivative, and second-derivative components. It is found that the derivative component counteracts the capacitor current feedback active damping, and both of them can be removed. Thus, the current sensor for sensing the capacitor current is saved. Instead, the LCL filter resonance is damped by the proportional and second-derivative feedback components, and a low-pass filter is added to the second-derivative component for ensuring a positive equivalent resistance within the full controllable frequency range. Experimental results from a 6-kW single-phase grid-connected inverter are provided to verify the effectiveness of the proposed method.

Post-Fault Direct Field-Oriented Control of Induction Motor Drive using Adaptive Virtual Current Sensor

Abstract: Electric drives immune to failures of selected elements of the power system or measuring sensors have been the subject of research in recent years, due to the growing interest in systems with an increased level of safety. The article concerns the analysis of the direct field-oriented control induction motor drive after the failure of all stator current sensors. An adaptive virtual current sensor (AVCS) was used to estimate the stator current, based on the measurement of the motor angular velocity and the voltage in the DC-bus of the voltage-source inverter. The paper presents the possibility of improving the accuracy of stator current estimation using the original approximation of changes in rotor resistance depending on the drive operating point when the measurement information about the stator current has been lost. This approximation was determined experimentally during normal operation of the drive using a rotor resistance estimator. The determined approximate look-up functions were used to adapt the rotor resistance in the AVCS during the drive system operation in a post-fault mode. This approach made it possible to significantly improve the accuracy of the stator current reconstruction, especially under low speeds and load torques, which was demonstrated in experimental studies.

Integrated G2V/V2G Switched Reluctance Motor Drive With Sensing Only Switch-Bus Current

Abstract: In this article, the integrated drive for three-phase switched reluctance motor (three-phase SRM) is proposed, and it combines a battery-powered bidirectional dc/dc converter to provide bidirectional power transfer in practice. In the proposed integrated drive, there is no relay to reconfigure and no need to add separate charging/discharging units and circuit components. Only one physical current sensor is used to sense the switch-bus current to provide all current signals not only for SRM driving, but also grid-to-vehicle/vehicle-to-grid functions at a standstill. The proposed integrated drive and its control are implemented and demonstrated by the provided results.

A Model-Based Sensor Fault Diagnosis Scheme for Batteries in Electric Vehicles

Abstract: The implementation of each function of a battery management system (BMS) depends on sensor data. Efficient sensor fault diagnosis is essential to the durability and safety of battery systems. In this paper, a model-based sensor fault diagnosis scheme and fault-tolerant control strategy for a voltage sensor and a current sensor are proposed with recursive least-square (RLS) and unscented Kalman filter (UKF) algorithms. The fault diagnosis scheme uses an open-circuit voltage residual generator and a capacity residual generator to generate multiple residuals. In view of the different applicable state of charge (SOC) intervals of each residual, different residuals need to be selected according to the different SOC intervals to evaluate whether a sensor fault occurs during residual evaluation. The fault values of the voltage and current sensors are derived in detail based on the open-circuit voltage residual and the capacity residual, respectively, and applied to the fault-tolerant control of battery parameters and state estimations. The performance of the proposed approaches is demonstrated and evaluated by simulations with MATLAB and experimental studies with a commercial lithium-ion battery cell.

Inductive Power Transfer Systems With Digital Switch-Controlled Capacitor for Maximum Efficiency Point Tracking

Abstract: Inductor–capacitor–capacitor-series (LCC-S) compensation topology has been widely used in inductive power transfer (IPT) systems due to its constant coil current regardless of the load and the coupling coefficient. Usually, the inductance of transmitter coil is sensitive to misalignments of the magnetic coupler when the asymmetrical coil structure with a smaller size receiver coil is adopted. The fluctuation of the inductance of transmitter coil will increase the power losses in the primary inverter. To compensate the fluctuation of the transmitter coil inductance, a digital switch-controlled capacitor (D-SCC) for maximum efficiency point tracking (MEPT) of LCC-S compensated IPT system is proposed. Consequently, the proposed LCC-S compensated IPT system can achieve high efficiency against the fluctuation of transmitter coil inductance. In traditional switch-controlled capacitor, high- frequency current sensor is required for the synchronization between the transmitter coil current and the driver signals of the switch-controlled capacitor. Nevertheless, the drive signals of D-SCC can be generated directly by the DSP controller in the primary side without detecting zero-cross points of the transmitter coil current, which can improve the system reliability and reduce the cost. Furthermore, the MEPT based on D-SCC is easy to be implemented because only the input dc current measurement is required. A 3.3-kW prototype is presented to verify the validity of the proposed D-SCC-based MEPT.

New Method for Spectral Leakage Reduction in the FFT of Stator Currents: Application to the Diagnosis of Bar Breakages in Cage Motors Working at Very Low Slip

Abstract: Motor current signature analysis has become a widespread fault diagnosis technique for induction machines (IMs), because it is noninvasive and requires low resources of hardware (a current sensor) and software (a fast Fourier transform) Nevertheless, its industrial application faces practical problems One of its most challenging scenarios is the detection of broken bars in IMs working at very low slip, like large machines with a very small rated slip, or unloaded induction motors in off-line tests In these cases, the leakage of the main supply component can hide the fault harmonics, even with a severe fault Diverse solutions to this problem have been proposed, such as the use of smoothing windows, advanced spectral estimators, or the removal of the supply component Nevertheless, these methods modify the spectral content of the current signal or add a high computational burden In this work, a new approach is proposed, based on the analysis of the current with a very fine spectrum, obtained via simple zero padding, followed by the extraction of a practically leakage-free conventional, coarse spectrum The method is experimentally validated by the diagnosis of a broken bar fault in a 315-MW induction motor

Simplified Nonlinear Voltage-Mode Control of PWM DC-DC Buck Converter

Abstract: This paper introduces a new nonlinear voltage-mode controller for a PWM dc-dc buck converter operating in continuous conduction mode. The sliding-mode control technique is used to derive a simplified equivalent control law based on the averaged dc-dc buck converter dynamics. As opposed to the reported design approaches, the proposed control scheme only requires the output voltage in the feedback loop without the need to the capacitor current. Thus, the analogue implementation cost is reduced and the drawback of adding a capacitor current sensor to the power converter is eliminated. The control equation is realized in a simple analogue circuit using few op-amps and resistors, which is suitable for industrial applications. The system modeling and control design procedure along with the derivation of the existence and stability conditions are presented. The control system performance is analyzed using MATLAB and SaberRD simulations. Furthermore, a simple analogue prototype of the simplified nonlinear voltage-mode controlled dc-dc buck converter is developed on a PCB. The simulation and experimental results show that the controller maintains a constant switching frequency, exhibits fast transient response, and provides good tracking performance under large disturbances.

Parameter Estimation of Batteries in MMCs with Parallel Connectivity using PSO

Abstract: Modular multilevel converters (MMCs) are a well-known solution in high-voltage applications. Recently, new topologies such as MMCs with series/parallel (MMSPC) connectivity are attracting large amount focus, due to their improved efficiency as well as self-balancing capability. Although MMSPCs can operate without direct measurement of modules’ voltages in battery-integrated modules, monitoring of the voltage and resistance of each module can still provide useful information to assess the state of each battery. However, including a voltage and current sensor in each module is not a cost-effective approach. This paper proposes a method to estimate the voltage and resistance of each battery-module using only the voltage and current measurement at load terminal. The proposed technique can reduce the number of sensors from 2N + 2 to only 2. Additionally, due to the self-balancing capability, the estimation technique does not require fast convergence and can operate in the background during the idling intervals of the processor. MATLAB simulations confirm the applicability of the proposed approach. The result show a 99 % and also 96 % accuracy for balanced and imbalanced systems.

High-Bandwidth High-CMRR Current Measurement for a 4.8 MHz Multi-Level GaN Inverter AC Power Source

Abstract: The control of very high switching frequency power electronic converter systems featuring latest generation wide bandgap (WBG) devices requires current measurements with a very high bandwidth (BW) to achieve high closed-loop control dynamics. One example is a ultra-high BW 4.8 MHz parallel-interleaved multi-level GaN inverter AC power source with a target output BW of 100 kHz. This work investigates the combination of state-of-the-art Hall-effect current sensors with a suitable high-frequency (HF) sensor to extend the BW of the commercially available current sensor by a factor of 20 – 50, i.e., up to 10 − 20 MHz. The main focus lies on a small form factor and a low realization effort. HF current sensors based on a Rogowski coil, an inductor integrated voltage sensing and a current transformer (CT) are analyzed and compared. Additionally, their respective performance limitations are highlighted. Furthermore, a precise combiner network to combine the low-frequency (LF) and HF signal is analyzed. The combiner circuit is designed in a way that component tolerances have no influence on the behavior in the transition frequency range from LF to HF. Thereby, also the immunity to Common-Mode (CM) disturbances, i.e., the high dv/dt occurring for the switching transitions of WBG semiconductors is considered. Finally, a hardware demonstrator featuring the two most promising current sensor approaches, i.e., the inductor voltage sensing and the CT, is presented and verified with comprehensive measurements in frequency and time domain. A BW from DC up to 35 MHz is measured. The realized sensors are further tested with a hardware prototype of the aforementioned AC power source switching 600 V at an effective switching frequency of 1.6 MHz. The measurements clearly reveal that both proposed sensor concepts are well suited for accurate measurements in fast switching converter systems with negligible additional volume.

Fast Commutation Error Compensation for BLDC Motors Based on Virtual Neutral Voltage

Abstract: Precise commutation signal is the prerequisite for the efficient operation of brushless direct current (BLDC) motors. However, the low-pass filter, nonideal current, circuit, and software retarding can bring about the commutation errors that will deteriorate the performance of BLDC motors, for example, resulting in larger current ripple and noise. To eliminate the commutation errors quickly and improve the performance of the motor, a novel compensation method is proposed in this letter. The compensation time is calculated by a counter. And the start–stop signals of the counter are obtained by the virtual neutral voltage. The proposed method requires none voltage or current sensor and has a faster compensation speed and higher precision than the traditional compensation method based on the integration of virtual neutral voltage. The effectiveness of the proposed method is verified by comparable exp eriments using an 80-W BLDC motor.

Design of Efficient Off-Grid Solar Photovoltaic Water Pumping System Based on Improved Fractional Open Circuit Voltage MPPT Technique

Abstract: The main application of off-grid solar photovoltaic (SPV) systems is water extraction in rural areas where access to the grid is restricted. In this application, photovoltaic (PV) and pump system regulation are crucial to increase its overall efficiency. In this context, this work presents a simple and efficient off-grid SPV water pumping system (SPVWPS). The designed system is based on a DC-DC boost converter, a three-phase DC-AC inverter, and a three-phase induction motor (IM) coupled to the centrifugal pump. The proposed solution is operated using a control strategy that associates an improved fractional open-circuit voltage (FOCV) method for maximum power point tracking (MPPT) and closed-loop scalar control. This association avoids the use of a speed sensor/encoder and a current sensor for the IM. Finally, the effectiveness of the proposed off-grid SPVWPS and its control system for both steady-state and dynamic conditions of insolation change is verified using a 1KVA rated prototype. The relevance of the drive is also checked in various operating conditions and is found to be adequate for pumping water. Moreover, the proposed method guarantees a fast response, less oscillations around the MPP, a system efficiency of 99%, and a high flow rate due to the extraction of maximum power.

Current and Speed Sensor Fault Diagnosis Method Applied to Induction Motor Drive

Abstract: The paper proposes a novel approach based on a current space vector derived from measured stator currents to diagnose speed and current sensor failures in the field-oriented control of induction motor drives. A comparison algorithm between the reference and measured rotor speed is used to detect the speed sensor faults. A counter is added to eliminate the influence of the encoder noise in the diagnosis method. In this approach, estimated quantities are not used in the proposed speed sensor fault diagnosis strategy, which increases the independence between the diagnosis stages in the fault-tolerant control (FTC) method. Moreover, in order to discriminate between the speed sensor faults and the current sensor faults, a new approach combining the current space vector and a delay function is proposed to reliably determine the current sensor failures. The MATLAB-Simulink software was used to verify the idea of the proposed method. Practical experiments with an induction motor drive controlled by DSP TMS320F28335 were performed to demonstrate the feasibility of this method in practice. The simulation and experimental results prove the effectiveness of the proposed diagnosis method for induction motor drives.

Robust Control Scheme for a Three Phase Grid-Tied Inverter With $LCL$ Filter During Sensor Failures

Abstract: This article discusses the operation of a three phase grid-connected inverter with $LCL$ filter under an unbalanced/distorted grid voltage condition. Two case studies are considered in this article that relate to the operation during grid side current and voltage sensor failure. First, a case study showing the operation of the inverter during a grid side current sensor failure is discussed. Second, a case study showing a grid voltage sensor failure is discussed. For the grid side current sensor failure methodology is developed and discussed to estimate the grid current from the sensed inverter current and the capacitor voltage reference. For the grid side voltage sensor failure, an internal model based grid voltage estimation architecture is proposed, and both its local and global stability analyses are presented. The controller design is based on the Lyapunov energy function, and its derivation during the two types of sensors failure have been discussed and presented along with a detailed mathematical analysis. The proposed architecture is verified on a reduced-scale laboratory prototype, and various case study results are presented.

Dual-Vector Located Model Predictive Control With Single DC-Link Current Sensor for Permanent-Magnet Linear Motor Drives

Abstract: In this article, a dual-vector located model predictive control (DL-MPC) method based on a single dc-link current sensor is proposed for the permanent-magnet linear motor drive system. In DL-MPC, the phase currents are reconstructed by sampled dc-link current and selected active voltage vector (VV). Meanwhile, the sunk number of phase current is defined to evaluate the accuracy of current reconstruction. The first-optimal and second-optimal VVs are determined by dual-vector location. The second-optimal VV is selected for the voltage source inverter when the sunk number exceeds the threshold. Compared with traditional MPC schemes, DL-MPC has smaller current tracking error and better dynamic performance. Meanwhile, DL-MPC has more accurate current reconstruction and lower computation burden than that of the traditional MPC. The effectiveness of DL-MPC is verified by both theoretical analysis and experimental results.

Sensorless Control for DC–DC Boost Converter via Generalized Parameter Estimation-Based Observer

Abstract: The full-information state feedback controller is usually used for regulating the output voltage of converters. Sufficient sensors should be adopted to measure all of the states. However, the extensive use of current sensors not only increases the cost of the overall system, but also affects the reliability. In this paper, the sensorless control problem of DC–DC boost converters is addressed to avoid the need for the current sensor. First, a PI passivity-based control (PI-PBC) is proposed to stabilize this converter. The main feature of this design is that the exponential convergence of the system is guaranteed. Afterward, a generalized parameter estimation-based observer (GPEBO) is presented to estimate the inductor current with the finite-time convergence (FTC). By adding this estimate in the above PI-PBC, a sensorless controller is developed. Thanks to this FTC, the exponential convergence of an overall closed-loop system is ensured. Finally, the simulation and experimental results are given to assess the performance of the proposed controller.

Common-Mode (CM) Current Sensor Node Design for Distribution Grid Insulation Monitoring Framework Based on Multi-Objective Optimization

Abstract: Insulation monitoring is essential in maintaining distribution grid reliable operation and common-mode (CM) current is an effective indicator for insulation deterioration of electrical assets. Traditional CM current measurement relies on current transformers or sensors physically connected to transmission buses, which suffers from low accuracy due to accompanied load current disturbance. This article presents an innovative CM current sensor node for insulation monitoring framework of power distribution systems based on magnetic field analysis. A CM current measurement model is developed based on formal magnetic field solution and device design is characterized as a multiobjective optimization problem solved by Pareto envelop-based selection algorithm. A prototype is presented with tunneling magnetoresistive sensor and experiments on power cable CM current measurement are implemented. Compared with conventional measurement devices, proposed sensor node realizes high-accuracy CM current monitoring in a more flexible and cost-effective manner.

A High-Efficiency Fast Transient COT Control DC–DC Buck Converter With Current Reused Current Sensor

Abstract: This article presents a high-efficiency fast transient constant on -time (COT) control dc–dc buck converter for the Internet of Things applications. The current reused current sensor is proposed to enhance the loop stability and improve the power conversion efficiency at light load. Input current is sensed and added to the feedback voltage of the dc–dc converter to increase the sensed output ripple voltage. Fast transient dc-offset cancelation technique is introduced to achieve a fast transient recovery time and to cancel the output dc offset. This chip is fabricated with a 0.13- μ m CMOS process. A standard supply voltage of 7–15 V is applied to produce the output voltage of 5–5.33 V. The total die area is 2 mm × 1.5 mm. The settling time is 17 μ s. The transient recovery time from light to heavy load and from heavy load to light load are 3 μ s and 2.7 μ s, respectively, with a maximum dc offset of 3.5 mV. The overshoot voltage is 85 mV and the undershoot voltage is 72 mV. The peak efficiency of the proposed design is 95.56% at 0.5 A and efficiency at the light load of 10 mA is 84.60%.

Extended Wide-Bandwidth Rogowski Current Sensor With PCB Coil and Electronic Characteristic Shaper

Abstract: Because of their fast switching speeds, current measurements for wide band-gap (WBG) devices have become increasingly challenging. Particularly, the designed current sensor must be nonintrusive and have a small size and a very wide bandwidth. One promising current sensor is the printed-circuit-board (PCB) Rogowski current sensor, whose bandwidth is wide only if parasitic parameters of its measuring coil are minimized prominently. This is presently achieved by reducing the number of turns of the coil, which undesirably will degrade its signal-to-noise ratio. Alternatively, an electronic characteristic shaper proposed in this letter can be used for neutralizing parasitic effects, while performing integration to restore the measured current. Theoretical analyses and experimental results have shown that the resulting Rogowski current sensor does indeed have a wider bandwidth, even without changing its measuring coil.

Self-Tuning Observer for Sensor Fault-Tolerant Control of Induction Motor Drive

Abstract: This paper introduces a new solution for the speed and current sensor fault-tolerant direct field-oriented control of induction motor drives. Two self-adjusting observers derived from a modified current-based model reference adaptive system (CB-MRAS) are presented. Finally, the recursive least squares method was used to estimate the parameters of the used observers. The method, in the proposed solution, provides a very fast and accurate finding of the observer parameters while maintaining relative simplicity and ease of implementation. The presented algorithm eliminates the CB-MRAS observer dependence on the induction motor parameters and also compensates for the inaccuracies in the evaluation of the stator voltage vector. The proposed fault-tolerant control offers the drive operation while either a speed sensor or one/two current sensors fault occurs. The drive still works with the direct field-oriented control even when no current sensors are healthy. The proposed scheme was simulated in the MATLAB/Simulink software environment. Then the algorithm was implemented in a floating-point digital signal controller (DSC) TMS320F28335 and tested on an induction motor drive prototype of rated power of 2.2 kW to validate the proposed schemes.

The X-Hall Sensor: Toward Integrated Broadband Current Sensing

Abstract: This article presents the X-Hall sensor, a viable sensing architecture for implementing a silicon-integrated, broadband, current/magnetic sensor. The X-Hall sensor overcomes the bandwidth limit of the state-of-the-art Hall sensors by replacing the spinning-current technique with dc-biased-based passive offset compensation. In this way, the X-Hall architecture removes the methodological bandwidth limit due to the spinning-current technique and allows for exploiting the Hall probe up to its practical limit, which is set by the parasitic capacitive effects. Moreover, the X-Hall architecture allows pushing the practical bandwidth limit at higher frequencies due to both the removal of the switches inherent in the spinning-current approach and a specially designed analog front end. To this end, a differential-difference current-feedback amplifier (DDCFA) is proposed as an analog front end in the X-Hall sensor. A prototype of the proposed X-Hall architecture is implemented in bipolar-CMOS–DMOS (BCD) 0.16- $\mu \text{m}$ silicon technology to experimentally assess the performance of the X-Hall architecture. The passive offset compensation implemented into the X-Hall architecture is frequency-independent and preserves an adequate offset reduction performance, though less efficient than the spinning-current technique operated at low frequency. Experimental dynamic tests on the prototype identify the presence of an additive parasitic dynamic perturbation due to the package that prevents from fully exploiting the X-Hall prototype up to its designed bandwidth limit. However, the implementation of a postdeemphasis digital filter allows us to mitigate for the dynamic perturbation and experimentally achieve a sensor bandwidth of 4 MHz, which is the broadest bandwidth ever demonstrated by a purely Hall-effect based sensor.

Phase-Shifting Fault-Tolerant Control of Permanent-Magnet Linear Motors with Single Phase Current Sensor

Abstract: In this paper, a phase-shifting fault-tolerant control (PS-FTC) with single phase current sensor is proposed for primary permanent-magnet linear motor (PPMLM) traction system. The phase with healthy sensor is defined as the first phase while the other two phases without healthy sensors are respectively defined as the second and third phases. In PS-FTC, hysteresis current control (HCC) is adopted. The actual currents of the second and third phases are replaced by the estimated values while the reference values are obtained by phase-shifting of the estimated first phase current. Although the linear motor parameters have been used in the calculation of the estimated currents, the parameter variations do not affect the performances of PS-FTC. Compared with existing schemes with single phase current sensor, PS-FTC is robust and shows better steady-state performances. The effectiveness of PS-FTC is verified by theoretical analysis and experimental results.