Commutation Principle Research Articles

An economical hybrid DC circuit breaker with pre-current-limiting capability

Multi-terminal flexible high-voltage-direct-current (HVDC) transmission and DC grid technology are developing rapidly, and the hybrid DC circuit breaker (DCCB) is usually used to protect the DC system, which can quickly remove the fault current and make sure the safe and stable work of system. However, the existing hybrid DCCBs have restrictions regarding one or more of the following characteristics: economy, fast adaptive reclosing, low on-state losses, and no additional pre-charge power source. This paper presents an economical hybrid DCCB with pre-current-limiting capability (EP-HCB), in which the main branch only is made up of mechanical switch (MS) and the fault handling branch consists of fault current transfer circuit, current limiting circuit and breaking circuit. And the proposed EP-HCB itself has inherent pre-charging and adaptive reclosing capabilities and low on-state losses, which efficiently limit the magnitude and rise rate of fault current and thus weaken the opening requirements on the DCCB. Detailed topology structure of the EP-HCB is presented, and the work principle of the fault current commutation and limiting are analyzed. Then, a design method for parameters of the proposed EP-HCB is provided. Finally, based on the 4-terminal simulation system in PSCAD/EMTDC, the feasibility and economy of the EP-HCB are proved by comparison with ABB hybrid DCCB.

A Fiedler-type determinantal inequality in Euclidean Jordan algebras

The Fiedler's determinantal inequality stated by M. Fiedler in [5] (1971) provides bounds for the determinant of the sum of two Hermitian matrices. In this note, we extend the Fiedler's result to Euclidean Jordan algebras. In our proof, we use the commutation principle for variational problems which was recently introduced in these algebras. As an application, we obtain some Minkowski-type determinantal inequalities in Euclidean Jordan algebras.

Comprehensive Analysis and Experiments of RB-IGCT, IGCT With Fast Recovery Diode and Standard Recovery Diode in Hybrid Line-Commutated Converter for Commutation Failure Mitigation

Commutation failure is one of the most important factors threatening the safety of multi-infeed high voltage direct current systems. To mitigate commutation failure, we have proposed a novel hybrid line-commutated converter by adding fully controlled devices to the conventional line-commutated converter. It aims to achieve auxiliary commutation and forced commutation with the help of fully controlled devices. Based on the novel hybrid line-commutated converter topology, the study investigates how to select suitable fully controlled devices and how to design the appropriate parameters of the devices. First, this article studied the general characteristics of reverse-blocking devices, including reverse-blocking integrated gate-commutated thyristor (RB-IGCT) and asymmetrical IGCT with diode (including fast recovery diode and standard recovery diode). Then, the novel commutation principle is carefully proposed and analyzed. The comprehensive simulation results and comparison study of the novel commutation principle are conducted. Then, according to the proposed commutation principle, the voltage and current working stress of devices are illustrated. According to these, vital features of devices, including recovery speed, <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state voltage, current conduction ability, surge current, maximum turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current, robustness, and volume of devices, are carefully analyzed and compared. Related experiments are conducted to present the vital characteristics of devices in the equivalent operating conditions in converters. Finally, the advantages and disadvantages of RB-IGCT and IGCT with fast recovery diode and standard recovery diode are comprehensively presented, which offers valuable reference considered in engineering applications.

Generalised homotopy and commutativity principle

In this paper, we study the action of special n×n linear (resp. symplectic) matrices which are homotopic to identity on the right invertible n×m matrices. We also prove that the commutator subgroup of O2n(R[X]) is two stably elementary orthogonal for a local ring R with 12∈R and n≥3.

Three-Phase Flying Capacitor Clamped Current Source Converter With Active Capacitor Voltage and CMV Control

AC-type flying capacitor (FC) concept has been proposed for current source converter (CSC) topologies recently, which offers unique merits over the traditional CSCs, such as lower <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> with improved dc-link voltage quality as well as flexible common-mode voltage (CMV) control. To cope with the main-stream three-phase industrial applications, in this article, the three-phase flying-capacitor-clamped CSC is introduced and extensively investigated for the first time. A novel space vector modulation is proposed, featuring a modular design process, active FC voltage control, and CMV suppression. The detailed commutation principles and the capacitor clamping voltage influence under different switching states are comprehensively addressed. Then, the redundant switching states are optimized to fulfill the multiple targets simultaneously. Simulation and experimental results are performed to demonstrate the superior dc-link power quality and CMV performance compared with the traditional three-phase CSC topology.

Dynamic Load Angle Estimation Through an Angular Domain GDFT Filter for Optimal Energetic BLDC Control

Nowadays, Brushless dc (BLDC) motors are increasingly used to drive speed-controlled applications (e.g., drones, air compressors, etc.) thanks to their high power density, good torque inertia ratio, and their simple square wave commutation principle. However, with growing attention toward energy usage, a more efficient sinusoidal current wave is favored over the classical square wave profile. Nevertheless, changing the waveform to absent the silence phase implicates that simple control principles (e.g., hall-sensors or back electromotive force tracing) are no longer functional, and a more advanced sensorless solution is required. Earlier, an innovative sensorless load angle based controller was suggested with the potential to overcome all restrictions concerning state-of-the-art sensorless control. One of the proposed estimator’s fundamental building blocks is a sliding discrete Fourier filter, requiring both a signal with a fixed base frequency and a full signal period of samples before updating completely. Both requirements severely limit the application field. This article presents an enhanced load angle estimator that can estimate the load angle 66% faster on average and without quality deterioration, regardless of the rotor speed. Both speed and accuracy of the estimated load angle are validated based on BLDC measurements, confirming the potential and revealing possible further estimation lag decreases if a limited estimation quality regression is allowed.

Commutation principles for optimization problems on spectral sets in Euclidean Jordan algebras

The commutation principle of Ramírez et al. (SIAM J Optim 23:687–694, 2013) proved in the setting of Euclidean Jordan algebras says that when the sum of a real valued function h and a spectral function $$\Phi $$ is minimized/maximized over a spectral set E, any local optimizer a at which h is Fréchet differentiable operator commutes with the derivative $$h^{\prime }(a)$$ . In this note, we describe some analogs of the above result by assuming the existence of a subgradient in place of the derivative (of h) and obtaining strong operator commutativity relations. We show, for example: if a solves the problem $$\underset{E}{\max }\,(h+\Phi )$$ , then a strongly operator commutes with every element in the subdifferential of h at a; If E and h are convex and a solves the problem $$\underset{E}{\min }\,h$$ , then a strongly operator commutes with the negative of some element in the subdifferential of h at a. These results improve known operator commutativity relations for linear h and for solutions of variational inequality problems. We establish these results via a geometric commutation principle that is valid not only in Euclidean Jordan algebras, but also in a broader setting.

Generalized Subdifferentials of Spectral Functions over Euclidean Jordan Algebras

This paper is devoted to the study of generalized subdifferentials of spectral functions over Euclidean Jordan algebras. Spectral functions appear often in optimization problems playing the role of "regularizer", "barrier", "penalty function" and many others. We provide formulae for the regular, approximate and horizon subdifferentials of spectral functions. In addition, under local lower semicontinuity, we also furnish a formula for the Clarke subdifferential, thus extending an earlier result by Baes. As application, we compute the generalized subdifferentials of the function that maps an element to its k-th largest eigenvalue. Furthermore, in connection with recent approaches for nonsmooth optimization, we present a study of the Kurdyka-Lojasiewicz (KL) property for spectral functions and prove a transfer principle for the KL-exponent. In our proofs, we make extensive use of recent tools such as the commutation principle of Ram\'irez, Seeger and Sossa and majorization principles developed by Gowda.

Numerical-field evaluation of an efficiency of a shortening of a three-phase stator winding of a cylindrical magnetic field inductor

The article proposes the implementation of the on-board battery system of energy accumulation of the DC rail - a reinforcing point that provides regulated parameters for the quality of electrical energy in the contact network. The expediency of using a matching converter, which provides the principle of separate commutation, in order to minimize the loss of switching of the power keys of the converter, is shown. The location of the reinforcement point in the immediate vicinity of the consumer - directly on the rolling stock - on a locomotive or in a special trailer car is substantiated. The energy and mass parameters of the system are estimated. The calculations are made to make the choice of specific power keys of the converter. The optimal frequency of switching of the power keys of the converter is determined, which provides a compromise between the overall properties of the magnetic elements and the losses in the magnetic material. The necessary value of transformer scattering inductance, mass of magnetic elements and batteries is estimated.

Dual-Stator Doubly Salient Electromagnetic Motor Driving System Utilizing a Nine-Switch Converter

This paper proposes a novel nine-switch converter for the dual-stator doubly salient electromagnetic motor (DSDSEM) in the compact and high-reliable driving system with 25% reduction of active switches compared with the conventional dual converter. The operation principle and mathematics model of DSDSEM are introduced, and the constraint relations of nine-switch topology for DSDSEM are given on the basis of the characteristics analysis of a nine-switch converter, then the corresponding commutation principles are proposed. Simultaneously, the influence of the interactions between the coupled outputs of the nine-switch converter is analyzed emphatically in the phase current commutation procedure. Besides, the advanced angle control strategy combined with the nine-state control strategy is optimized to eliminate the side effects of the interactions for the nine-switch converter. Finally, the effectiveness and feasibility of the control strategy of the proposed driving system are verified by the simulation and experiment results.

당률 명례편의 감형규정에 대한 연구

당률 명례편의 감형규정에 대한 연구

The Study of the Commutation Principles (of General rule) in T��ang Code

The Study of the Commutation Principles (of General rule) in T��ang Code

A High-Temperature Superconducting Pulsed-Power Supply Circuit With ICCOS

Recently, inductive energy storage systems have attracted interests due to high energy densities. The high-temperature superconducting pulsed-power supply (HTSPPS) is one inductive PS topology for electromagnetic launching system. The topology can achieve a high amplitude load current and cut down the electrical losses due to the zero resistance characteristic of superconducting inductors. However, in this topology, the integrated gated commuted thyristor is used as a switch and cannot withstand high current, which limits the expansion of the system. Besides, it has significant current amplification ability as a single unit, but one module cannot provide sufficient amplitude and appropriate pulsewidth for the load current of the electromagnetic launching. In this paper, by applying the principle of inverse current commutation with semiconductor devices (ICCOS) in the HTSPPS, a novel circuit topology called HTSPPS with ICCOS is presented. This topology is analyzed and the multiple modules system is established. Simulation results show that the HTSPPS with ICCOS exceeds the current limitations of the original one and ensures the reliable cutting off of the main switch. It has potential applications in the future of high-energy systems while reducing the cost greatly. By asynchronous cooperative triggered discharge of the multiple HTSPPS with ICCOS modules in parallel, the appropriate amplitude and flat shape current of the load can be achieved through the careful design of the trigger time.

Extended commutation principles for normal decomposition systems

In this paper we study some optimization problems on Lewis' normal decomposition systems (1996, 2000). We extend Gowda and Jeong's commutation principle (2017) in two directions. Firstly, we replace the sum operation by an arbitrary binary operation monotone in each variable. Secondly, we employ G-increasing functions in place of G-invariant convex functions. We give applications to some classes of matrices. We also interpret the obtained results for simple Euclidean Jordan algebras.

Cascaded commutation circuit for a hybrid DC breaker with dynamic control on fault current and DC breaker voltage

This study proposed a cascaded commutation circuit based on current commutation approach for low- to medium-voltage DC fault current interruption, without snubber circuits, which slows the fault current di/dt prior to current-zero and the rate of rise of the transient recovery voltage dv/dt across the mechanical breaker contacts after current-zero. The proposed dynamic control of the fault current di/dt and circuit breaker voltage dVVCB/dt increase the fault current interruption capability at the first and second current-zeros. Detailed mathematical equations are presented to evaluate the operational waveform profile and the validity of the cascaded commutation principle is confirmed by simulation and experimental results at 600 Vdc, 110 and 330 A.

Homotopy and commutativity principle

We give evidence for the principle that a (special linear, symplectic, orthogonal) matrix over a commutative ring which is homotopic to the identity will commute up to an elementary matrix with all elements of the (respective) group.

Commutation Principles in Euclidean Jordan Algebras and Normal Decomposition Systems

The commutation principle of Ramírez, Seeger, and Sossa [SIAM J. Optim., 23 (2013), pp. 687--694] proved in the setting of Euclidean Jordan algebras says that when the sum of a Fréchet differentiable function $\Theta$ and a spectral function $F$ is minimized (maximized) over a spectral set $\Omega$, any local minimizer (respectively, maximizer) $a$ operator commutes with the Fréchet derivative $\Theta'(a)$. In this paper, we extend this result to sets and functions which are (just) invariant under algebra automorphisms. We also consider a similar principle in the setting of normal decomposition systems.

Children's understanding of the commutativity and complement principles: A latent profile analysis

This study examined patterns of individual differences in the acquisition of the knowledge of the commutativity and complement principles in 115 five-to six-year-old children and explored the role of concrete materials in helping children understand the prinicples. On the basis of latent profile analysis, four groups of children were identified: The first group succeeded in commutativity tasks with concrete materials but in no other tasks; the second succeeded in commutativity tasks in both concrete and abstract conditions, but not in complement tasks; the third group succeeded in all commutativity tasks and in complement tasks with concrete materials, and the final group succeeded in all the tasks. The four groups of children suggest a developmental trend – (1) Knowledge of the commutativity and of the complement principles seems to develop from thinking in the context of specific quantities to thinking about more abstract symbols; (2) There may be an order of understanding of the principles – from the commutativity to the complement principle; (3) Children may acquire the knowledge of the commutativity principle in the more abstract tasks before they start to acquire the knowledge of the complement principle. This study contributes to the literature by showing that assessing additive reasoning in different ways and identifying profiles with classification analyses may be useful for educators to understand more about the developmental stage where each child is placed. It appears that a more fine-grained assessment of additive reasoning can be achieved by incorporating both concrete materials and relatively abstract symbols in the assessment.

Fostering Formal Commutativity Knowledge with Approximate Arithmetic

How can we enhance the understanding of abstract mathematical principles in elementary school? Different studies found out that nonsymbolic estimation could foster subsequent exact number processing and simple arithmetic. Taking the commutativity principle as a test case, we investigated if the approximate calculation of symbolic commutative quantities can also alter the access to procedural and conceptual knowledge of a more abstract arithmetic principle. Experiment 1 tested first graders who had not been instructed about commutativity in school yet. Approximate calculation with symbolic quantities positively influenced the use of commutativity-based shortcuts in formal arithmetic. We replicated this finding with older first graders (Experiment 2) and third graders (Experiment 3). Despite the positive effect of approximation on the spontaneous application of commutativity-based shortcuts in arithmetic problems, we found no comparable impact on the application of conceptual knowledge of the commutativity principle. Overall, our results show that the usage of a specific arithmetic principle can benefit from approximation. However, the findings also suggest that the correct use of certain procedures does not always imply conceptual understanding. Rather, the conceptual understanding of commutativity seems to lag behind procedural proficiency during elementary school.

A Hybrid DC Vacuum Circuit Breaker for Medium Voltage: Principle and First Measurements

A novel concept of hybrid dc vacuum circuit breakers (VCBs), based on the combination of zero-voltage switching (ZVS) and zero current switching principle, was developed to meet the needs of the dc zonal distribution system on shipboard rated for a current of several kiloamperes and a voltage of several kilovolts. In normal operation, the VCB handles the continuous flow of dc current, minimizing the onstate losses. When protection against the fault is requested, the current is first divided between the VCB and the static branch before being quickly interrupted under a forced commutation principle. Laboratory tests have been dedicated to characterize the reliability of the high-current commutation from the VCB to the static branch and the turnoff characteristic of the silicon-controlled rectifier under high-current conditions. Finally, the critical design of the high-speed VCB is discussed.