Semiconductor Rectifiers Research Articles

Spin–orbit torque rectifier for weak RF energy harvesting

We propose a rectifier concept, simultaneously utilizing the Hall effect and the spin–orbit-torque, that is well matched to the low impedance of antennas. This rectifier is promising for general radio detection and, particularly, for harvesting ambient weak radio signals, where conventional rectification fails to operate. The Hall effect and spin–orbit-torque are both proportional to current density, which improves inversely with the device cross-sectional area, providing a large signal at the nanoscale. A single device made using existing materials can provide 200 μV DC from 500 nW of radio frequency (RF) power. A series array of such devices can efficiently enhance the DC voltage to 300 mV while matching the receiver antenna impedance. Such magnetic devices can convert weak RF power into DC power with substantial efficiency at low voltage and low impedance where conventional semiconductor rectifiers fail.

MODELING THYRISTOR TRANSDUCERS IN MATLAB ENVIRONMENT TAKING INTO ACCOUNT THE PECULIARITIES OF THEIR IMPLEMENTATION

The authors present the study of synthesis methods for simulating the models of semiconductor rectifiers. Simulation of semiconductor rectifiers is quite studied today, but many authors carry out synthesis in their own unique way. The need to apply high technologies in variable speed drives with the development of mechanisms and working machines is growing, the automated variable speed drive is being introduced increasingly, making the energy substrate for aggregates and working machines. The relevance of this work is explained by the fact that currently developing technologies make it possible to manufacture more advanced semiconductor elements. The more relevant and significant is the study of refined digital models of electric drives containing semiconductor converters. This paper will summarize known approaches to the development of rectifiers’ digital models, as well as it will offer the authors’ own vision of this issue – taking into account as many individual features of semiconductor elements and the entire electric drive system as a whole as possible. The option proposed for consideration differs in that when developing in Matlab environment the parameters of real existing power elements and their digital analogues are consistent. The article also examines the issue of creating a digital model of the electric drive reverse system including a thyristor transducer and an engine; the transition characteristics of the refined model are illustrated. The result of this study is the analysis of different approaches to modeling semiconductor converters in electric drive systems. In this regard, a refined approach to modeling semiconductor rectifiers was considered, consisting of maximizing approximation of the model structure to real implementation, taking into account all elements, included in the structure of the ventilated electric drive. The study suggests that the developed simulation models can be used for the design of a real power converter in the conditions of a production enterprise.

Highly Efficient Multilevel Frequency Converters of Metallurgical Production Facilities

A comparative analysis of traditional and multilevel low-voltage frequency converters was performed. Calculation methods were proposed that make it possible to evaluate the technical and economic indices of multilevel semiconductor devices. The attractive qualities of low-voltage multilevel frequency converters as compared with high-voltage (with rated voltage exceeding 1 kV) multilevel semiconductor devices were distinguished. In low-voltage multilevel converters, the loss in semiconductor rectifiers was reduced by about 1.5 times, the effect of overvoltage in the load was decreased, and the operating speed of the active rectifier was increased. A method of estimation of the loss in semiconductor converters with two-level standalone inverters based on mathematical models and experimental studies is proposed, which made it possible to clarify the parameters of analytical equations. It is stated that using the three-level bridge inverters (rectifiers) in active rectifiers makes it possible to shorten the durability of transient process of the system in the regeneration mode because of a reduced level of switching overvoltages. A method of choosing the optimal number of phases of semiconductor multilevel low-voltage frequency converters for metallurgical production facilities according to the criterion of maximum probability of failure-free operation was developed.

Switching Performance up to 150°C of β-Ga2O3 Field-Plated Vertical Schottky Diodes for 0.3-1 a Forward Current and 300-900 V Reverse Voltage

In the past few decades, wide-bandgap SiC (3.3 eV) and GaN (3.4 eV) based semiconductor rectifiers have shown promising results in power electronic switching and control applications. [1] Recently, Ga2O3 has attracted significant interest for its outstanding potential in power electronics due to superior material properties and availability of high-quality substrate and n-type epistructures. [2,3] The energy band gap of Ga2O3 is in the range of 4.5 – 4.9 eV, which corresponds to a ~8 MV/cm theoretical breakdown electric field. Reverse breakdown voltages larger than 1 kV were reported for both unterminated Ga2O3 vertical rectifiers (1000 V and 1600 V) and field-plated Ga2O3 Schottky diode (1076 V and 2300 V) with an epi thickness of 8 µm and 20 µm, respectively. [4,5,6,7] Furthermore, the switching characteristics of Ga2O3 vertical Schottky diodes were also investigated, and the recovery time was in the range of 20 to 30 ns. [6,7] This indicates an impressive potential application for high power switching devices. In this study, field-plate edge-termination was utilized on a lightly doped 20 µm Ga2O3 epitaxial layer to greatly improve the Ga2O3 vertical rectifier breakdown voltage. In addition, we demonstrate that an 8 µm epitaxial layer of β-Ga2O3 on bulk conducting substrates can achieve forward currents in the 1 A range with a reverse breakdown voltage of 760 V. Field-plated edge-terminated (FPET) Schottky diodes with a reverse breakdown voltage of 2100 V (0.1 cm × 0.1 cm) and an absolute forward current of 1 A with 760 V of breakdown voltage (Diameter = 0.1 cm) were achieved on 20 and 8 µm epi-Ga2O3, respectively. The recovery characteristics for Ga2O3 FPET Schottky diode switching from forward current of 1 A and 0.3 A to reverse off-state voltage of -300 V and -900 V with recovery time (trr) of 60 ns and 81 ns were demonstrated on diodes with drift layers thickness of 8 µm and 20 µm with 4.4 × 1015 cm-3 and 2.0 x 1015 cm-3 Si-doped epi-Ga2O3 layer, respectively. There was no significant temperature dependence of trr up to 150°C. These results are an important milestone towards the applications of Ga2O3 vertical Schottky rectifiers in high power device and high-speed switching technologies.

ChemInform Abstract: A Brief Survey on Basic Properties of Thin Films for Device Application

AbstractReview: 19 refs.

Investigation of rectenna for microwave power conversion

This paper presents the fabrication of organic semiconductor (OS) rectifiers and an investigation of rectifying antenna (rectenna) under the effect of microwave power. As a source of microwaves, a patch antenna fed by a generator was used. The rectenna contains a built-in rectifier. The surface-type Ag/NiPc/Au cell, with organic semiconductor nickel phthalocyanine (NiPc) as the active material, was used as a rectenna. The rectifier was fabricated by thermal deposition of Ag, Au and NiPc thin films on thoroughly cleaned glass substrate. The measured I–V characteristics of the cell showed rectifying behavior. The rectenna was tested at frequency ranges of 8–16 GHz at different intensities of radiation and vertical and horizontal positions of the rectenna's axes. Under the effect of microwave power at the output of the rectenna, the output dc voltage and current were detected.

Design and application of semiconductor rectifier transformers

The design of semiconductor rectifiers made obsolete the older mercury-arc rectifiers. Accordingly, the transformer standards were modified to address the differences in the two types of transformers supplied for these applications. Short-circuit problems were reduced with the new technology, but harmonic heating became a bigger problem. The Transformers Committee of the IEEE Power Engineering Society developed the new standard for semiconductor power rectifier transformers. This paper intends to highlight some of the major aspects of how specification, design, and testing of semiconductor rectifier transformers have changed based on the new standard, as well as other design and application consideration.

Wirtschaftswunder in Pretzfeld, upper Franconia: Interactions between science, technology, and corporate strategies in Siemens semiconductor rectifier research & development, 1945–1956

Immediately after World War II, when emergency production of non‐electrotechnical products such as stoves, pots, etc. at Siemens amounted to more than 50% and the return to normal production and old standards was the primary company goal, one man, Eberhard Spenke, thought far ahead. Power semiconductor rectifiers were to be designed and manufactured on a scientific basis rather than as a result of trial and error methods. The theory of rectification in semiconductor‐metal contacts that had been found by the Siemens theoretical physicist Walter H. Schottky was to serve as a starting point. First, apartments for researchers had to be built in a former stable at Pretzfeld Castle, Upper Franconia; lab equipment was then procured. On September 1, 1947, research work began, and the first selenium rectifiers were made on three old kitchen tables. In 1956, Spenke proudly presented the world's first reproducible silicon power rectifier elements (for a reverse voltage of 1000 V and a maximum forward current of 300 A when forced‐air‐cooled) at the international semiconductor conference in Garmisch‐Partenkirchen, Bavaria. Siemens had thus become a world leader in power electronics. The example of Eberhard Spenke and his team can give valuable guidelines for organizing Research & Development efficiently within a big corporation. It shows that the amount of money spent on R&D is not necessarily the determining factor of success. At least equally important are such elements as personal leadership in small research groups rather than bureaucratic administration of research, the ability to foresee technological and market developments, direct contacts between the leading researchers and the top management, open‐mindedness of the top management to new ideas and approaches, and the motivation of employees.

Performance evaluation of high-power wide band-gap semiconductor rectifiers

Applicability of GaN in unipolar and bipolar devices for high-power electronic applications is evaluated with respect to similar devices based on other materials. Specific resistance is used as a measure of unipolar performance. In order to evaluate bipolar performance, 700 and 6000 V p-i-n diodes based on Si, 6H-SiC, and GaN are compared with respect to forward conduction and reverse recovery performance at room temperature and high-temperature conditions. It is shown that GaN is advantageous not only for high voltage unipolar applications, but also for bipolar applications. An empirical closed-form expression is presented to predict the avalanche breakdown voltage of wide band-gap semiconductors. Formulation of the expression is based on an approximation of the impact ionization coefficient in terms of seventh power of the electric field.

Real-time determination of power system frequency

The main frequency is an important parameter of an electrical power system. The frequency can change over a small range due to generation-load mismatches. Some power system protection and control applications, e,g, frequency relay for load shedding, load-frequency controller, require accurate and fast estimation of the frequency. Most digital algorithms for measuring frequency have acceptable accuracy if voltage waveforms are not distorted. However, due to nonlinear devices, e,g, semiconductor rectifiers, electric arc furnaces, the voltage waveforms can include higher harmonics. The paper presents a new method of measurement of power system frequency, based on digital filtering and Prony's estimation method. Simulation results confirm, that the proposed method is more accurate than others, e,g, than the method based on the measurement of angular velocity of the rotating voltage phasor.

The mercury-arc rectifier and supply to electric railways

The introduction in the 1890s of the heavy-duty LVDC rapid-transit railway, drawing current from an AC power station, required some form of rectifier for converting the supply to DC in the conductor rail or contact wire. The development of the HVDC railway by 1915 likewise necessitated rectifiers. Though the principle of using the mercury arc to convert AC to DC was well understood by 1905, the first valves, owing much to Cooper-Hewitt, were too low in capacity to serve railway needs before the early 1920s, and railway electrification relied on rotary converter sets. By the 1920s, both the glass-bulb and steel-tank types of mercury-vapour rectifier were sufficiently developed to be used in railway service, first for battery charging, then as supplements to rotary sets, and finally as main power rectifiers. Throughout the 1930s, both the glass-bulb type, and the multianode steel-tank rectifier were installed in automatic substations, remotely controlled. In Great Britain, London Transport pioneered their extensive use. Between 1945 and 1965, the air-cooled, pumpless rectifier found favour, but the developments in solid-state semiconductor rectifiers led to their replacement throughout industry. The types of mercury-arc rectifier mounted on locomotives proved unreliable in this service, and hence relatively few were used in this capacity. In stationary use, all major types of mercury-arc rectifier performed well, and in railway service the majority were employed in lineside substations.

Current equalising transformer for current balance in parallel-connected 12-pulse converter

There has been a serious problem of current out-of-balance in 12-pulse rectifiers between two 6-pulse groups. This has become particularly pronounced with semiconductor rectifiers where 12-pulse operation is obtained by two phase-displaced 3-phase bridge rectifier circuits operating in parallel. A current equalising transformer (CET) was introduced to overcome the problem. A new simpler variation of this has more recently been introduced and the paper describes this new variation and includes more complete and exact design current and voltage relationships than have previously been published.

Reliability of electronic components Part 4: Reliability of semiconductor diodes and rectifiers

Reliability of electronic components Part 4: Reliability of semiconductor diodes and rectifiers

The failure of cathodic protection equipment during lightning storms

The paper reports on a study into the operational behaviour of pipeline cathodic protection schemes in areas of high lightning activity. The work is supported by an on-site investigation of recorded failures and complemented by laboratory based lightning simulation tests on test pieces removed from service. The ageing effect of semiconductor rectifiers, owing to repeated high surge voltages, is discussed a and design recommendations are made for future protection units so as to reduce the incidence of failure.

Precision measurement of forward voltage drop of semiconductor power rectifiers

Precision measurement of forward voltage drop of semiconductor power rectifiers

Measuring static characteristics of semiconductor high-power rectifiers

The above testing technique is suitable for obtaining volt-ampere characteristics of high-power amplifiers under pulsed operating conditions, and this is very important for various investigations. The inclusion in these measuring circuits of an element which limits the maximum power loss of the tested rectifiers increases substantially the reliability of these circuits and protects the tested rectifiers from damage. Measurement of the semiconductor rectifiers' static parameters by means of instruments with pointer or digital indicating meters accelerates testing and raises its precision.

Determination of DC Bus Fault Currents for Thyristor Converters

Maximum surge current is one of the important ratings of semiconductor rectifiers. There are several methods in the literature for calculating dc bus fault currents. These methods have largely been devoted to rectifier equipment without phase control.

The asymmetric heat conduction of semiconductor rectifiers

We offer a survey of existing literature dealing with the problem of asymmetric heat conduction of semiconductor rectifiers, and we present the experimental results achieved by the authors of this article.

Use of power semiconductors to control locomotive traction motors in the French national railways

The application of semiconductor rectifiers and thyristors in the control of power to ac, dc, and diesel powered locomotives in the French National Railways is presented. A total of 260 locomotives have been equipped with 60 000 semiconductor rectifiers since 1959. The failure rate of these rectifiers has been 0.12 percent or 1.35 percent for every million kilometers traveled. Four locomotives have been equipped with thyristor control circuits and it is anticipated that all future single-phase ac powered locomotives will use thyristors.

Use of capacitors for reduction of commutation angle in static high-power convertors

With the usual methods of connecting static capacitors as a reactive-power source on the primary or tertiary of a convertor transformer, their latent ability to produce a rapid discharge current, which will directly assist the commutation process and so reduce commutation angle, is not utilised. By connecting the capacitors to the secondary winding (valve winding) of the convertor transformer, appreciable reduction of commutation angle can be obtained, resulting in a saving in reactive-power consumption, which is particularly important in the case of invertor operation. Investigation shows that the connection of capacitors alone on the valve winding produces transient overvoltages, and that these can be eliminated by incorporating the capacitors in a suitable filter configuration. This also results in improved filtering of current harmonics compared with primary- or tertiary-connected filters. Other advantages and disadvantages have been assessed, and theoretical calculations have been experimentally confirmed. Provision of capacitive filter circuits on the transformer secondary is particularly commendable for convertors using semiconductor rectifiers.