Voltage Measurement Method Research Articles

GaN-based p-type metal-oxide–semiconductor devices with a gate oxide layer grown by a bias-assisted photoelectrochemical oxidation method

In this work, a bias-assisted photoelectrochemical (PEC) oxidation method was used to form an oxide insulator for GaN-based p-type metal-oxide–semiconductor (MOS) devices. The inversion breakdown and accumulation breakdown fields of the resulting GaN p-type MOS devices were 11.6 MV cm−1 and 3.7 MV cm−1, respectively. The interface-state density of the GaN p-type MOS devices was 4.18 × 1011 cm−2 eV−1 obtained by a photo-assisted capacitance–voltage measurement method. In addition, the negative fixed oxide charge of 2.4 × 1012 cm−2 eV−1 was also estimated.

An Accurate Capacitance–Voltage Measurement Method for Highly Leaky Devices—Part II

In Part I, an accurate - measurement based on time-domain reflectometry (TDR) for MOS capacitors in the presence of a high level of leakage across the gate dielectric was presented. This new method is expected to have high accuracy even in the presence of a very high level of leakage current. In this paper, the basic TCR-based - measurement is extended to handle the parasitic, allowing the overlap capacitance to be extracted simultaneously and accurately without the need for additional measurement. In addition, a detailed error analysis is provided to complete the description of the TDR - measurement method.

Effect of n-value on third harmonic voltage method analyzed by finite element method

To investigate the correctness of the estimation of the critical current density J c in high- T c superconductor by third harmonic voltage measurement method, the third harmonic voltage V 3 and the distributions of magnetic flux and current in a superconducting film with various n-values are calculated by FEM using the n-value model. When the AC current I 0 cos ω t is applied to a coil, the threshold coil current I th , which is proportional to J c in the film, is determined by so-called off-set method for V 3/ I 0– I 0 curve which is frequently used in the four terminal method. The calculated value of I th is slightly smaller than that of theoretical value by Bean’s model. When the coil current I 0 is smaller than I th , although the current density distribution is almost uniformly distributed as predicted by Bean’s model, the value of current density is smaller than J c . This behavior is different from the prediction of Bean’s model. It is found that the current density is uniform and is equal to J c for high n-value when I 0 is closed to I th . Therefore, it seems to be reasonable to estimate J c by I th in the above method for superconducting films with n-value higher than 20.

Communication between a Matrix Converter Modulator and a Superset Regulator

This work deals with the modulator of a matrix converter and its communication with the superset regulator. A switching algorithm is briefly introduced. The input voltage measurement method is presented. In the last part of the paper, the testing of communication between the superset regulator and the modulator in FPGA technology are also presented.

Instantaneous voltage measurement technique for PWM voltage source inverters

The pulse width modulated (PWM) voltage source inverter (VSI) is almost universally used in industrial motor drives. Although measurement of the VSI output voltage is required in many applications, accurate measurement is problematic due to the high frequency inverter switching. Many commonly used inverter output voltage measurement methods, such as indirect and direct voltage measurement, produce inaccurate results under a variety of operating conditions. In this paper, the common sources of voltage measurement error are identified and an instantaneous voltage measurement technique is presented that significantly reduces inaccuracies introduced by common voltage measurement strategies. Implementation details of the proposed strategy are outlined and experimental results are used to compare the proposed technique with other methods of inverter output voltage measurement. The results demonstrate the opportunity for improvements to any inverter-driven motor control system that requires precise terminal voltage measurements to carry out the intended control objective.

A prognostic method for the embedded failure monitoring of solder interconnections with 1149.4 test bus architecture

This paper describes the feasibility of accurate low frequency measurements in predicting the breakdown of modern lead free ball grid array (BGA) interconnections. In these measurements, performed partly with 1149.4 analogue boundary scan, ceramic BGA modules measuring 15×15mm in width, with 9×9 ball matrixes, were attached on an FR-4 printed wiring board (PWB) and thermally cycled over a temperature range of −40 to +125°C. The condition of corner interconnections was monitored using the developed measurement methods and construction. In-situ measurements were performed with a datalogger during temperature cycling, accompanied with 1149.4 mixed-signal test bus measurements of corner interconnections performed between cycling intervals. In addition, the measurements were complemented by scanning acoustic microscopy and, X-ray. Monitoring corner interconnections by a simple, low-frequency voltage measurement method with embedded test constructions gives an early warning indication well before the electrical interconnection failures. Of two studied interconnection compositions, the ones with plastic core solder balls (PCSB) proved to be more reliable than the ones with 90/10 PbSn balls.

Method for a fast measurement of built-in voltage inside closed cavity MEMS-devices

A method to measure built-in voltages on the material interfaces in capacitive MEMS-devices inside closed cavities is presented. The method is based on a vibrating capacitor (Kelvin-probe) principle and it can even be used to measure closed cavity samples. The suggested set-up is tested by measuring various capacitive accelerometers and the results are compared with those obtained from capacitance–voltage (C–V) measurements. The potential of the method for high-speed measurements is explored by demonstrating an accurate determination of built-in voltages by measuring only a few data points for a device due to a very highly linear response of the method.

Evaluation of film thickness dependency of the reversible fluxoid motion in the third harmonic voltage method

Significant overestimation of the critical current density Jc is found for the third harmonic voltage measurement method for thin YBCO superconductors. This is caused by a reversible flux motion in pinning potentials, which is known to be significant for superconductors of thickness comparable to or smaller than Campbell’s AC penetration depth. In this paper the effect of reversible flux motion on the estimation of Jc by this method with different thicknesses is also theoretically investigated by using the Campbell model for the force–displacement characteristics of flux lines. Although the factor of overestimation can be approximately explained by the Campbell model, agreement is not satisfactory. It is considered that the variation in the flux motion from reversible to irreversible states seems to take place much faster than assumed in the Campbell model.

Development of quench protection system for HTS coils by active power method

Recently, HTS coils have been developed for electric power apparatuses. In superconducting coils, local and excessive joule heating may give damage to the superconducting windings when a quench occurs and therefore it is essential that the quench is detected quickly and precisely so that the coils can be safely discharged. Resistive voltage measurement method is universally used for the quench detection, however, it is vulnerable to an electromagnetic noise which causes insufficient quench detection and at least needs a central voltage tap in windings. In a large superconducting coil, a lead-wire from the central voltage tap may cause a short-circuit when high voltage will be applied. In this paper, we present a quench protection system based on the active power method which detects a quench by measuring the instantaneous active power generated in a superconducting coil. The protection system based on this method is very strong against to the noise and no more needs a central voltage tap. The performance of system developed by us is confirmed by using test coil wound with Bi-2223 HTS tapes.

Modified quadrature method for accurate voltage measurement in optical voltage transducer

There are fewer problems encountered with optical voltage transducers in comparison with their inductive and capacitive counterparts. As a result they are considered as proper candidates for replacing conventional inductive and capacitive transformers. Lighter weight, smaller size, larger dynamic range, wider bandwidth, insensitivity to electromagnetic interference, stability over temperature change, absence of iron core saturation, low maintenance and replacement cost, are some of the advantages of optical voltage transducers over inductive and capacitive transformers. A modified quadrature method is introduced to measure the voltage with the minimum number of sensors. Another advantage of this method is the possibility of improving the accuracy of the measurement by using a correction factor. The correction factor is determined by considering the level of accuracy, environmental conditions and the number of sensors. Simulation results show the validity and effectiveness of this method over a wide range of variation.

Characteristics of an address discharge in ac plasma display panels

In this study, the basic characteristics of an address discharge have been investigated on the dependence of an address pulse voltage and its characteristics were analyzed by the wall voltage measurement method. During the address operation, the discharge between an address electrode and a scan electrode is first generated by an address pulse voltage and then the discharge between a scan electrode and a common electrode is induced. The resultant wall voltage between the address electrode and a scan electrode is strongly dependent on an address pulse voltage while the resultant wall voltage between a scan electrode and a common electrode is roughly independent on an address pulse voltage.

A method for cross-sensitivity and pull-in voltage measurement of MEMS two-axis accelerometers

An electronic circuit for the characterization of two-axis accelerometers is presented, implementing a non-linear method which reduces the effect of parasitic signals. Single-ended and differential measurements were used to extract a value of 0.15 for the cross-sensitivity of the device. Other parameters, like the pull-in voltage, the quality factors and the resonance frequencies, are extracted as well. Curves of the frequency response at different pressure levels, and with different dc bias voltages are presented.

Magnetic interactions in FePt∕soft magnetic underlayer double-layered structure observed by anomalous Hall effect

The effect of magnetic interactions between an FePt recording layer with perpendicular magnetic anisotropy and a soft magnetic layer of FeCoB (or NiFe) was investigated using the anomalous Hall voltage measurement method. The nucleation field and the slope around the coercivity of the Hall hysteresis loop revealed by the recording layer were found to significantly decrease depending on the type of interface. The coercivity corresponding to the in-plane magnetization components of the soft magnetic layer was found to increase while coexisting with an FePt layer.

Switching Current Study: Hysteresis Measurement of Ferroelectric Capacitors using Current–Voltage Measurement Method

In this study, we utilize the current–voltage (I–V) measurement method for investigating the ferroelectric characteristics of ferroelectric capacitors, such as hysteresis loops, switching current characteristics, retention properties and depolarization characteristics. By applying triangular voltage wave forms without sweeping and measuring delay, the hysteresis switching current characteristic was determined and the polarization–voltage (P–V) loop could be obtained using an integral calculus. Additionally, two kinds of poling measurement were utilized to investigate the full-switching and nonswitching current characteristics. A strong agreement was found between nonvolatile polarization (ΔP) obtained from P–V loops and that obtained by poling measurements. Moreover, modified poling measurements were utilized to study the retention property of ferroelectric capacitors. A dynamic switching current characteristic was found in retention duration and an increased coercive voltage was also observed in its half-hysteresis loops as remaining time increased. Furthermore, another modified poling profile was utilized to investigate the depolarization characteristics of ferroelectric films.

Characteristics of a wall voltage during sustain period in AC plasma display panels

According to the viewpoint of a driving scheme, the luminance and luminous efficiency is mainly determined during the sustain period. Therefore, it is very important to understand the characteristics of the wall voltage during the sustain period, which is essential to design the driving pulse scheme. In this study, the quantitative analysis of the wall voltage has been carried by the wall voltage measurement method during the sustain period. The initial difference of the wall voltage is sharply stabilized due to the sustain discharges and it is mainly determined by the sustain voltage. The wall voltage between the sustain electrodes is changed symmetrically for the reference voltage level, while the wall voltage between the address and sustain electrode is positively sustained which is roughly mean value of the total effective voltage.

Voltage measurement based on the electrostrictive effect with simultaneous temperature measurement using a 3 × 3 fiber-optic coupler and low coherence interferometric interrogation

A fiber-optic interferometric method for remote voltage measurement with simultaneous temperature measurement is presented. A PMN electrostrictive transducer is employed as a voltage-to-displacement converter. The displacement is then interferometrically measured by the passive demodulation technique based on a 3 × 3 fiber-optic coupler. The third 3 × 3 coupler’s port and the same low coherence light source (LCS) are used for the interferometric temperature measurement, necessary for the correction of the electrostrictive coefficient values.

Effects of input voltage measurement on stability of matrix converter drive system

The effects of different input voltage measurement methods on the stability of a matrix converter drive system are analysed. In particular, with the aim of improving the maximum output power of the matrix converter, the duty cycles of the switching configurations are calculated using input voltages filtered by a digital lowpass filter. A variable state average model of the whole system, which takes into account the grid impedance, the input L–C filter parameters and the load, is used for the theoretical analysis. The stability of the system is evaluated by analysing the migration of eigenvalues of the system, which is linearised around a steady-state operating point. The analytical approach allows the determination of the maximum power for a stable operation of the matrix converter as a function of the time constant of the digital lowpass input voltage filter. Theoretical considerations are supported by simulation results, showing the varying behaviour of the matrix converter that can be achieved in terms of stability as the time constant of the digital filter is changed.

Multi-prove electric potential change method for delamination monitoring of graphite/epoxy composite plates using normalized response surfaces

Delamination is a significant defect of laminated composites. The present study employs an electric potential change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing graphite fibres as sensors. In our previous paper, a two-prove method was adopted for the electric-resistance change measurements because of the simplicity. The two prove method is not appropriate for a precise measurement, and it tends to include a large experimental error in the electric resistance change owing to the electric resistance change at the electrodes. Instead, the present paper employs a multiple-prove method for the measurements. In the present study, high precise measurement system of electric voltage change is developed, and the electric voltage measurement method is adopted for identification of embedded delamination location and size. Measured electric potential data are normalized for creations of response surface to identify the delamination. As a result, the new multi-prove electric potential method is shown to be effective for the identifications of embedded delamination cracks of graphite/epoxy composite laminates.

Smart Structure for Detection of Embedded Delamination of CFRP Plates Using Multi-Point Voltage Change.

The present study employs an electric voltage change method for the identifications of location and size of embedded delamination cracks of CFRP plates. Measurements of electric voltage change at multiple points are robust against electric resistance change of electrodes, and the method is usually called four-probe method for high precision measurements of electric resistance change. However, our previous analysis showed the method is less sensitive than the method that uses change of electric resistance between the electrodes. In the present study, high precise measurement system of electric voltage change is developed, and the electric voltage measurement method is adopted for identification of embedded delamination location and size. As a result, the electric voltage change method is shown to be useful for the identifications of embedded delamination cracks of CFRP plates.

A diagnostic method based on RVM (return voltage measurement) for condenser bushings with oil-paper insulation systems

The bushing of a transformer is one part of the transformer system, but is as vital as the transformer itself because it forms a part of the main circuit. Deterioration and abnormal condition of the bushing possibly cause its destruction, shortage of the main circuit to the Earth, and fire in the systems, so that diagnosis of the bushings is thus very important. At present, mainly visual inspection from outside of the bushing is carried out. Inspection of the inside condition of the bushing by dissolved gas analysis of the inside oil is done only as sampling for selected bushings because it is difficult due to the sealed construction of the bushings. Therefore, a simple diagnostic method for bushings has been expected for a long time. In Eastern Europe, the RVM (Return Voltage Measurement) method based on scanning the polarization spectra was applied to the oil–paper insulation systems inside the transformer as a diagnostic method. In this paper we investigate theoretically the principle of the RVM method applied to bushings with the same oil–paper insulation systems as the transformer by using the equivalent circuit, and the possibility of using this novel diagnostic method for condenser-type bushings is demonstrated by a model experiment. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 21–29, 2000