Resistive Voltage Drop Research Articles

Pseudo‐Vertical Schottky Diode with Ruthenium Contacts on (113) Boron‐Doped Homoepitaxial Diamond Layers

Electrical properties of pseudo‐vertical Schottky barrier diodes (pVSBDs) prepared on (113)–oriented boron‐doped diamond (BDD) layers using ruthenium (Ru) for both the ohmic and Schottky contacts are investigated. First, Ru ohmic contacts are evaporated on homoepitaxial BDD layers with different resistivity, and their specific contact resistance is measured using circular transfer length method structures after annealing at various temperatures up to 750 °C. Then, pVSBD structures are fabricated on the boron‐doped bilayer consisting of a lower, heavily boron‐doped layer ensuring an ohmic contact and an upper, lightly doped layer providing a rectifying Schottky contact. After necessary mesa etching, both contacts are formed by the Ru evaporation. The results show that Ru forms a stable ohmic contact with very low contact resistance (10−5–10−6 Ω cm2) when deposited on BDD layers with metallic conductivity. It also provides an acceptable Schottky contact on low‐doped (113) homoepitaxial BDD. Both contacts, which are made simultaneously, realize pVSBDs with low on‐state resistance and low forward voltage drop. However, the lower barrier of the ruthenium contacts results in higher leakage. Ru pVSBDs thus show a lower rectification ratio, higher leakage, and a worse ideality factor compared to analogical pVSBDs using molybdenum contacts.

Simultaneous salt recovery and zwitterionic stachydrine purification from saline eluent via two-stage electrodialysis system

To date, saline eluent from the ion exchange process in the extraction of traditional Chinese medicine such as Leonurus japonicus Houtt was treated predominantly by the conventional processes such as evaporation, crystallization and ethanol elution. However, large amount of energy and fresh organic solvent need to be consumed in the above processes. In the present study, two-stage electrodialysis (ED) was proposed to simultaneously recover salt and purify zwitterionic stachydrine from the saline eluent. In the first stage ED, the membrane type and current density were optimized, and then the continuous twenty-batch operation in partial cyclic mode was carried out to increase the concentration of the recovered NaCl solution. Subsequently, the second stage ED was carried out to further purify the above desalinated saline eluent. Results indicate that, after the two-stage ED process, the concentrated NaCl solution can be directly recycled due to the high concentration of 2.9 mol/L; the recovery rate and purity of NaCl can reach to high values of 99.8% and 99.6%, respectively; the recovery rate and purity of stachydrine can reach to high values of 95.6% and 99.3%, respectively. In addition, a low energy consumption (∼8.34 kWh/m3) was required for the two-stage ED system. What’s more, the membrane fouling investigation indicated that there are as little as 0.5% of the total stachydrine in the saline eluent adsorbed into the CEM. Nonetheless, ED process can be operated stably due to the relatively stable membrane resistance and cell pair voltage drop. Hence, the two-stage ED system is a high-efficient, environmentally-friendly and economical process for simultaneous salt recovery and zwitterionic stachydrine purification from the saline eluent.

Offline Measurement of Stator Resistance and Inverter Voltage Drop Using Least Squares

Modern industrial and commercial electrical drives are typically designed to control motors of different types, operating under scalar, field-oriented or direct torque control. These drives execute various algorithm such as sensorless control, temperature monitoring, etc., which require the knowledge of motor drive parameters. In order to do this, the inverters allow data to be input manually or execute self-commissioning routines before running the motor. The parameters necessary for proper operation include motor phase resistance and inverter voltage drop, which are especially important in low-speed range. This paper presents an offline technique for estimation of mentioned parameters, which can be obtained with enough precision for the overwhelming majority of applications. The proposed algorithm consequently injects DC-current of several levels into the stator of a motor, measuring the corresponding voltages. Each pair of current and voltage is a point in the voltage current characteristic of motor drive, thus set of these points maybe approximated with a first order polynomial using least squares method. The parameters of polynomial are desired inverter voltage drop and phase resistance. The experimental section analyzes estimation errors and their dependence on the number of injected levels, their values and filtering capability of measuring algorithm. After that, the authors give suggestions on algorithm parameters selection, depending on the demanded precision. Finally, the authors demonstrate a mass-producing dishwasher motor drive, which adopted this technique.

Analysis of Limiting Output Capacity of Low-Speed and High-Torque Surface-Mounted Permanent Magnet Motor Considering Resistance Voltage Drop

Analysis of Limiting Output Capacity of Low-Speed and High-Torque Surface-Mounted Permanent Magnet Motor Considering Resistance Voltage Drop

Extremely low speed performance research of the speed sensorless vector controlled induction motor drive system

This paper proposes a new full-order adaptive observer algorithm to overcome the instability of speed sensorless vector control system of induction motor at low speed, especially at extremely low speed. The algorithm consists of the improved feedback matrix algorithm and the improved speed adaptive law algorithm. By establishing an observer state error equation considering the non-linear voltage error of the inverter and the stator resistance voltage drop, a feedback matrix was designed to reduce the effect of inverter's non-linear voltage error and stator resistance voltage drop on speed estimation. Meanwhile, this paper improves the traditional adaptive law. The basic idea is to add compensation amount equivalent to the non-linear voltage error, and the compensation amount is adaptive to the running speed and load to improve the motor speed estimation accuracy at low speed. Extensive experimental tests have been carried out to evaluate the performance of the proposed algorithm using a 2.2 kW induction motor experimental platform. The experimental results show that the algorithm presented in this paper can guarantee the stable operation of the motor under the rated-load and 180% rated-load at low, extremely low and 0 speed with good dynamic and static characteristics.

Modeling of nanohole silicon pin/nip photodetectors: Steady state and transient characteristics

Theory is proposed for nanohole silicon pin/nip photodetector (PD) physics, promising devices in the future data communications and lidar applications. Photons and carriers have wavelengths of 1 μm and 5 nm, respectively. We propose vertical nanoholes having 2D periodicity with a feature size of 1 μm will produce photons slower than those in bulk silicon, but carriers are unchanged. Close comparison to experiments validates this view. First, we study steady state nanohole PD current as a function of illumination power, and results are attributed to the voltage drop partitions in the PD and electrodes. Nanohole PD voltage drop depends on illumination, but series resistance voltage drop does not, and this explains experiments well. Next, we study transient characteristics for the sudden termination of light illumination. Nanohole PDs are much faster than flat PDs, and this is because the former produces much less slow diffusion minority carriers. In fact, most photons have already been absorbed in the i-layer in nanohole PDs, resulting in much less diffusion minority carriers at the bottom highly doped layer. Why diffusion in PDs is slow and that in bipolar junction transistors is quick is discussed in appendix.

Equivalent calculation of aperiodic component of thermal effect of DFIG with short circuit fault

The temperature rise caused by three-phase short current at stator side of doubly fed induction generator (DFIG) may damage DFIG and its adjacent electrical equipment. By using the step-by-step integration, the thermal effect may be quantified, but the contribution of periodic component and aperiodic component of thermal effect cannot be distinguished, and the amount of calculation is large. In this paper, the steady-state component of rotor flux is considered to reduce the error of analytical expression of short current. The components of short current are decomposed and the square of the short current is integrated. The calculation method of equivalent duration of aperiodic component of thermal effect is proposed, and the effect of equivalent duration on different crowbar resistance and stator voltage drop ratio is quantified. The simulation results are provided to validate the accuracy of the proposed models.

Real-Time Optimal Torque Control of Interior Permanent Magnet Synchronous Motors Based on a Numerical Optimization Technique

This study presents a real-time optimal torque control scheme for interior permanent magnet synchronous motors (IPMSMs). The proposed scheme enables computation of optimal current reference for a torque reference under all operating regions, including the maximum torque per ampere (MTPA), flux weakening (FW), maximum current (MC), and maximum torque per voltage (MTPV), using numerical optimization techniques to simplify the problems and obtain the corresponding solutions with reduced computation burden. Linearizing the torque equation of IPMSM is utilized to derive solutions for the MTPA and FW. These solutions are proved to converge to their optimum with the aid of the reference smoother. Numerical solutions for the MC and MTPV are derived based on the assumption that the resistive voltage drop is small enough but not zero. These solutions differ from the existing solutions that ignore the resistive voltage drop. The effectiveness of the proposed method is numerically and experimentally verified using a 7.5-kW IPMSM with a considerable reduction in computational time of approximately 90% in the simulation compared with the analytic solution.

Flux-Weakening Control for Variable Flux Reluctance Machine Excited by Zero-Sequence Current Considering Zero-Sequence Resistive Voltage Drop

In the control of variable flux reluctance machine (VFRM) excited by zero-sequence current, neglecting the zero-sequence resistive voltage drop would cause a large calculation deviation of the stator voltage, which can saturate the inverter and influence the switching from constant torque region to flux-weakening region. To solve with this problem, a flux-weakening control method considering the zero-sequence resistive voltage drop for VFRM is proposed. Firstly, the relationship between dq-axis voltages, zero-sequence voltage and the maximum voltage is presented. Secondly, based on the deduced voltage constraint, the calculation of optimal reference currents in flux-weakening region is presented by using Lagrange multiplier method. Since the zero-sequence voltage is considered, the calculation accuracy of the stator voltage and the utilization rate of DC link voltage are improved, which improves the output power capability. Finally, the proposed method is verified by the experimental results.

A Novel ZVS High-Step-Up Converter With Built-In Transformer Voltage Multiplier Cell

This article proposes a novel interleaved high-step-up dc-dc converter with zero voltage switching (ZVS). Through a built-in transformer voltage multiplier cell (VMC) the high voltage conversion ratio is achieved without the narrow duty. By applying active clamp scheme, all of the power MOSFETs are switched with ZVS which minimizes the switching losses of the proposed converter. Besides the voltage stress across the switches is decreased and can be controlled by the built-in transformer turns ratio enabling utilization of low on-state resistance and low forward voltage drop semiconductors. Due to the interleaved structure, the input current ripple is minimized and the thermal stress is shared between the phases. Meanwhile, the charge balance of the capacitors give rise to equal current sharing performance for the two input inductors. All of these factors reduce the power losses and improves the performance of the proposed converter. Finally, in order to verify the operation of the proposed converter, a 35-V input voltage to 500-V output voltage prototype with the rated power of 1 kW is fabricated and tested in the laboratory.

An Accurate Wide-Speed Range Control Method of IPMSM Considering Resistive Voltage Drop and Magnetic Saturation

This paper deals with the high accurate current set-points solution for interior permanent-magnet synchronous motors (IPMSM) in wide-speed range applications. Considering voltage and current constraints, the operating regions can be divided into maximum torque per ampere, maximum current, field weakening, and maximum torque per voltage regions, which requires solving different nonlinear functions in real time to obtain optimal current set-points. Traditional methods including curve-fitting methods and polynomial approximation (PA) methods are not easy to obtain these solutions, especially involving magnetic saturation problems. In this paper, Newton-Raphson algorithm for improving the control accuracy of the current set-points is proposed. Meanwhile, parameters influence including magnetic saturation and resistive voltage drop is fully investigated. Compared with PA method, the proposed method is able to converge to accurate solutions in few numbers of iterations with reduced execution time, which can be easily implemented on an off-the-shelf digital signal processor. Both simulation results and experimental results on an 8-kW IPMSM rig are conducted showing good agreement with the expected results.

Robust Self-Calibrated Dynamic Voltage Scaling in FPGAs With Thermal and IR-Drop Compensation

Field programmable gate arrays (FPGAs) are widely used in telecom, medical, military, cloud computing, and other high-performance computing applications, thanks to their unique combination of parallel hardware execution and reprogrammability. During compilation, the computer-aided design (CAD) tool estimates the maximum operating frequency of the user application based on the worst case timing analysis of the critical path at a fixed nominal supply voltage, which usually results in significant voltage or frequency margin. Hence dynamic voltage scaling (DVS) has great potential to reduce the power overhead in FPGAs; however, the reprogrammability of FPGAs make a safe implementation of DVS for any application that could be programmed into the FPGA challenging. This work presents a robust universal DVS scheme for FPGAs intended to run on a system production line, or regularly during each FPGA power-up. The proposed scheme requires the FPGA to be programmed twice: offline self-calibration and online DVS. During the offline self-calibration, the FPGA frequency and core voltage operating limits at different self-imposed temperatures are automatically found and stored in a calibration table (CT). During online operation, the power stage refers to the CT and dynamically adjusts the core voltage according to the FPGA temperature and the resistive voltage drop in the power delivery path. The proposed DVS scheme is demonstrated on a 60-nm Intel Cyclone IV FPGA, with a digitally controlled dc–dc converter, leading to 40% power savings in two typical applications.

Design techniques for a stable operation of cryogenic field-programmable gate arrays.

In this paper, we show how a deep-submicron field-programmable gate array (FPGA) can be operated more stably at extremely low temperatures through special firmware design techniques. Stability at low temperatures is limited through long power supply wires and reduced performance of various printed circuit board components commonly employed at room temperature. Extensive characterization of these components shows that the majority of decoupling capacitor types and voltage regulators are not well behaved at cryogenic temperatures, asking for an ad hoc solution to stabilize the FPGA supply voltage, especially for sensitive applications. Therefore, we have designed a firmware that enforces a constant power consumption, so as to stabilize the supply voltage in the interior of the FPGA. The FPGA is powered with a supply at several meters distance, causing significant resistive voltage drop and thus fluctuations on the local supply voltage. To achieve the stabilization, the variation in digital logic speed, which directly corresponds to changes in supply voltage, is constantly measured and corrected for through a tunable oscillator farm, implemented on the FPGA. The impact of the stabilization technique is demonstrated together with a reconfigurable analog-to-digital converter (ADC), completely implemented in the FPGA fabric and operating at 15 K. The ADC performance can be improved by at most 1.5 bits (effective number of bits) thanks to the more stable supply voltage. The method is versatile and robust, enabling seamless porting to other FPGA families and configurations.

Permanent Magnet Flux Online Estimation Based on Zero-Voltage Vector Injection Method

In this paper, a simple and accurate method is proposed for online estimation of the rotor permanent magnet (PM) flux linkage for surface mounted PM synchronous machines. By advantageously utilizing an injected zero-voltage vector, the effects of inductance in estimating the PM flux linkage is eliminated. The inverter voltage error and phase resistive voltage drop effects are minimized by repeating the test at different speeds. Therefore, as a result, only the voltage commands are needed for PM flux linkage estimation, resulting in great simplicity. Filtering the current ripple caused by the zero-voltage vector injection is not necessary. The proposed method can be used with sensored or sensorless field-oriented control strategies. The experimental results have shown a good accuracy of the proposed new method.

Stationary Frame Induction Motor Feed Forward Current Controller With Back EMF Compensation

In this paper, a novel induction motor (IM) stator current controller is proposed based on the stationary frame feed forward controlling structure. The proposed regulator represents an improved variant of the existing stationary and rotational frame IM stator current regulators based on the back EMF compensation. The paper novelty consists of the stationary frame controlling structure based on two feed forward actions that enable asymptotic reference tracking. Namely, the novel stationary frame regulator includes a proportional integral (PI) regulation term combined with a stator resistance voltage drop and back EMF feed forward compensations, with the back EMF compensation based on the stator flux value estimated by means of a programmable low-pass filter. The feedback term is based on a PI controller, with the corresponding parameter tuning procedure outlined in the paper. The simulation runs are included in the paper in order to examine the regulator performance in relation to the factors critical to the IM stator current regulation: variable IM model parameter values, transport delay introduced in the control loop, variable stator frequency, and rotor speed values. Also, the experimental tests are presented and carried out on an experimental setup for different operating conditions typical for an IM drive.

ENERGY EFFICIENT REVERSIBLE BUILDING BLOCKS RESISTANT TO POWER ANALYSIS ATTACKS

Reversible logic circuits consist of a chain of reversible gates with many stages. The existing transmission gate-based implementation of reversible gates severely suffers from voltage degradation because of the inherent resistive voltage drop when cascaded. In addition, the propagation delay increases quadratically with the number of transmission gates cascaded in reversible circuits. To circumvent these problems in cascaded circuits, static CMOS buffers or latches are generally inserted at intermediate stages. But the static CMOS latches are inherently irreversible and cannot be used in reversible circuits. In this work, a novel adiabatic reversible latch is proposed to regenerate the voltage levels at intermediate stages in cascaded reversible circuits. The proposed latch is placed at the target line of each transmission gate-based reversible gate implementation to restore the logic to their respective voltage levels and at the same time reduces the energy consumption significantly. In addition, the proposed adiabatic reversible gate implementations show resistance against power analysis attacks as the current drawn from the power supply matches for all cases of input stimulus.

Transient Analysis of Circuit Containing Massive Conductors

Inductive electrical components made of massive conductors are usually adopted in the high-power circuit. Since they are not the types of filaments, the diffusion of the electromagnetic fields inside the conductors plays an important role in the transient discharge. Though the behavior of the circuit can be described reasonably using constant electrical parameters, the voltage drop in the massive conductor is not expressed accurately when constant resistance and inductance are used in the analysis of the transient discharge. To obtain a more accurate waveform of the pulsed current, we have used a comprehensive method calculating the correction voltage in the voltage drop. Once the resistive voltage drop and the magnetic flux for a step-function current are obtained either analytically or numerically, the voltage drop in the massive component for any current waveform can be calculated using the Duhamel's integration. The equations of the circuit containing massive conductors can be solved through a few iterations using the method estimating the voltage drop. As an example, the method was applied to an analysis of an RLC circuit containing a massive pulse-forming inductor. Electromagnetic responses of the inductor for a step-function current were calculated numerically with the help of a finite element method. The current waveform calculated using the method of correction voltage showed a good agreement with the measured waveforms.

Scale‐up design of a 300 kA magnesium electrolysis cell based on thermo‐electric mathematical models

Magnesium production process is highly energy intensive. Electrolysis provides an effective route to reduce energy consumption and greenhouse gas emission for the magnesium production. This paper concerns the scale‐up design of a 300 kA magnesium electrolysis cell using a three‐dimensional thermo‐electric mathematical model. The model provides information on the steady‐state thermoelectric fields thus allowing the evaluation of the effects of structure parameters (anode–cathode distance, anode thickness, cathode thickness, anode width, and anode number) on the current intensity, resistance voltage drop, and current density. Non‐dimensional analyses give a linear relation between the current intensity and a set of dimensionless numbers, which upon further comprehensive analyses, gives a criterion for the scale‐up. Such a scale‐up criterion is found to be able to predict, within 1%, the amperage of 300 kA magnesium electrolysis cells. The results suggest that the criterion could be used for the scale‐up design of magnesium electrolysis cells with a high current intensity.

Flux-Weakening Control of Nonsalient Pole PMSM Having Large Winding Inductance, Accounting for Resistive Voltage Drop and Inverter Nonlinearities

This paper proposes an improved flux-weakening control method to improve the drive performance of nonsalient pole permanent magnet synchronous motors having large winding inductance and consequently an infinite constant power speed ratio. The proposed method consists of two parts. The first part utilizes the voltage differences between the input and output of a minimum-magnitude-error over-modulation block to modify the d-axis current references. The second part uses the compensated q-axis voltage, in which the resistive voltage drop and the distorted voltage due to inverter nonlinearities are taken into account, to detect the maximum torque per voltage (MTPV) line. Under the MTPV condition, a PI controller with a low-pass filter is presented to modify the q-axis current reference. With these two parts, the bus voltage utilization in the proposed method is close to the six-step operation and the actual current trajectory approaches the ideal MTPV line. As a result, the drive performance in the whole flux-weakening region is optimized in terms of maximizing the output torque/power. The method also shows a good performance in transient response. Effectiveness and superiorities of the proposed method are verified by experimental results.

Fractal Power Network Based on Plant Vein for Power Integrity

In this paper, a fractal power network has been proposed. The structure is designed based on leaf vein. The simulated and measured results illustrate that the designed power network has greatly improved noise isolation, resistive and inductive voltage drop, and “Swiss Cheese” effect.