Current Commutation Research Articles

Design of adaptive speed controllers for matrix‐converter‐based interior permanent magnet synchronous motor drive systems

AbstractInterior permanent magnet synchronous motors (IPMSMs) which are driven by matrix converters have many advantages, including one‐stage power conversion, high efficiency, bidirectional power transfer, near unity input power factor, and low input current harmonics. However, the virtual DC‐link voltages of matrix‐converters vary from 0.866 to and the current commutations of matrix‐converters create serious three‐phase stator harmonic currents as well. Moreover, matrix‐converter‐based IPMSM drive systems, in general, have very large external loads, which require advanced control methods. To solve these problems, two adaptive controllers, including a model reference adaptive controller and a self‐tuning controller, are investigated in this article for matrix‐converter PMSM drive systems. From the experimental results, the proposed two adaptive speed controllers provide excellent dynamic responses, which are superior to PI speed controllers, including faster transient responses, better tracking abilities, and greater robustness. As a result, this proposed matrix‐converter‐based IPMSM drive system is very suitable in industrial applications.

Soft‐switching boundary and piecewise control of LLC converter with hybrid modulation

AbstractThe voltage gain range of LLC converter can be effectively broadened by using the hybrid modulation of phase‐shift modulation (PSM) and pulse frequency modulation (PFM). However, the harmonic of resonant tank increases dramatically in PSM mode, and the first harmonic approximation is no longer suitable for solving the voltage gain. Moreover, the conditions for soft switching in PSM mode are not clear. Meanwhile, the small‐signal models of the converter in different modulation modes are quite different, and it is difficult for a fixed controller to ensure a good dynamic performance of the converter in both modulation modes. To address above issues, a voltage gain modeling method of PSM mode LLC converter is proposed. By establishing the function between input current and resonant current, the voltage gain model of the converter is obtained according to the power conservation. Moreover, considering the parasitic capacitance charge and resonant current commutation time, the condition for soft switching is derived. Furthermore, a control strategy of LLC converter in hybrid modulation is proposed. The piecewise proportional integral (PI) controller is adopted, and the parameters of the controller are dynamically adjusted with the modulation mode, so that the converter has excellent dynamic performance in both modes. And the hysteresis control is used to ensure the stability of mode switching. An experimental prototype with 200–340 V input and 28 V/1 kW output was built based on gallium nitride (GaN) devices. The peak efficiency was 97.82%, and the power density was 65.76 w/in3.

A novel controllable capacitor commutation based superconducting hybrid direct current breaker

Featuring low power loss and high reliability, voltage source converter medium voltage direct current (VSC-MVDC) systems have been widely employed for grid-tied renewable energy applications. To maintain high operational safety, circuit breakers are needed to isolate faulted powerlines by comprehensively considering response speed and installation cost. Research efforts have been put to realizing DC fault isolation by coordinating resistive type superconducting fault current limiter (R-SFCL) and integrated-gate-commutated-thyristor (IGCT) based hybrid DC circuit breaker. In this paper, a controllable current commutation based superconducting DC circuit breaker (CCCB-SDCCB) is proposed. By integrating R-SFCL with IGCT based hybrid DC circuit breakers, the current interrupting capacity can be greatly enlarged with the advantage of low cost and fast speed, and hence the overall cost for suppress large fault currents can be greatly reduced for MVDC systems. In addition, a new current injection circuit branch using H-bridge structure is designed to recycle the residual capacitor voltage from the previous fault stage to trigger the IGCTs without the capacitor pre-charging process. Simulation results show that the fault current can be successfully suppressed from 24.2 to 2.1 kA and fully interrupted within 4.11 ms by the proposed CCCB-SDCCB.

Optimization of an IPMSM for Constant-Angle Square-Wave Control of a BLDC Drive

Interior permanent magnet synchronous machines (IPMSMs) driven with a square-wave control (i.e., six-step, block, or 120° control), known commonly as brushless direct current (BLDC) drives, are used widely due to their high power density and control simplicity. The advance firing (AF) angle is employed to achieve improved operation characteristics of the drive. The AF angle is, in general, applied to compensate for the commutation effects. In the case of an IPMSM, the AF angle can also be adjusted to exploit reluctance torque. In this paper, a detailed study was performed to understand its effect on the drive’s performance in regard to reluctance torque. Furthermore, a multi-objective optimization of the machine’s cross-section using neural network models was conducted to enhance performance at a constant AF angle. The reference and improved machine designs were evaluated in a system-level simulation, where the impact was considered of the commutation of currents. A significant improvement in the machine performance was achieved after optimizing the geometry and implementing a fixed AF angle of 10°.

Model Predictive Control Strategy Based on Loss Equalization for Three-Level ANPC Inverters

Targeting the issue of high losses of individual switching tubes in Neutral-Point Clamped (NPC) three-level inverters, an Active Neutral-Point Clamped (ANPC) three-level inverter is used, and a model predictive control strategy using the loss equalization of the inverter is proposed. This method organizes and analyzes multiple zero-state current pathway commutation modes and adds mode three under the original two commonly used zero-state commutation modes. On this basis, the three modes are flexibly switched by model predictive control, and the output is optimized according to the value function for the space vector in each operation, while the midpoint voltage control is added to the value function. The simulation results suggest that the recommended strategy in this study may effectively realize the loss equalization control and midpoint voltage control of the ANPC inverter, which improves the operation efficiency of the electromechanical actuator.

Analysis on Improving the Utilisation Rate of Commuter Railways in Mature Metropolitan Areas in China in the Context of High-quality Development

China’s six mature metropolitan areas are facing a shortage of land resources. Commuter railways are a solution to this problem in the context of high-quality development. Nevertheless, the current commuter rail utilisation rate in these metropolitan areas is significantly lower than those in developed countries. Therefore, on the basis of analyses through the literature survey method, this paper collects the latest data on commuter railway services in the six metropolitan areas to discuss the reasons for the current low utilisation of commuter railways in terms of coverage, efficiency and operation, and to propose corresponding practicable solutions. The study found that the number of routes currently in operation is too small. In addition, there are issues including irrational station distribution, sparse train frequency and short operating hours and slow interchange in the services, all of which make the commuter railways fail to achieve the idealised time-saving effect, and serve as a reason for commuters to rely on private cars. In the foreseeable future, with the imposition of the concepts of sustainable development, transportation integration and service orientation, there is possibility that the utilisation rate of commuter railways in these metropolitan areas will be elevated.

Analysis, Modeling, and Experiments of a Nonlinear Inductor-Based Fault Current Commutation Strategy for a Hybrid Dc Circuit Breaker

Analysis, Modeling, and Experiments of a Nonlinear Inductor-Based Fault Current Commutation Strategy for a Hybrid Dc Circuit Breaker

A fuse‐based DC circuit breaker with vacuum interrupter enhanced by an external transverse magnetic field

AbstractDue to the increasing power system capacity, the interruption of large fault currents has gradually become a major challenge in power systems. At the moment, such currents are interrupted mainly via circuit breakers based on the method of active current commutation. However, these types of circuit breakers tend to be costly and oversized. One possible alternative—a fuse‐based circuit breaker with current commutation process enhanced by an external transverse magnetic field (ETMF)—is proposed by the authors. Its main advantage lies in the fast current commutation achieved by an ETMF‐enhanced three‐stage increase of the vacuum arc voltage. The study of the current commutation process is mainly represented by the authors, and the influencing factors of the current commutation—contact opening speed and ETMF current—are discussed. At last, the proposed circuit breaker is verified by an experiment, whose results show that a short‐circuit current of 42 kA can be interrupted within just 2 ms.

Development of a Thyristor-Assisted Hybrid DC Circuit Breaker for Reduced Cost and Size

The hybrid DC circuit breaker (HCB) is an important equipment for clearing DC faults and maintaining the safe operation of DC grids. The current transition from a mechanical switch to a power electronic switch has always been a crucial issue in HCB, and existing HCBs generally require dedicated auxiliary commutation devices, which bring additional cost and size. To address the key issue, this letter proposes an improved thyristor-assisted hybrid DC circuit breaker (TA-HCB) solution. A novel thyristor commutation module (TCM) integrated into the transfer branch not only enables current commutation, but also can assist the power electronic switch in withstanding a portion of the static DC voltage during interruption, greatly reducing the volume and cost of the HCB. After a detailed illustration of the operation process and the voltage distribution process, a 3 kV/ 6 kA prototype experiment was conducted to verify the feasibility of this TA-HCB.

A novel control method for enhanced performance of single‐phase matrix converters

AbstractThe conventional topology of direct single‐to‐single‐phase matrix converter (SSMC) is widely adopted in industrial and power system‐related applications owing to its desired features. Current control methods in the literature either limit the voltage transfer ratio (VTR) or prohibit their utilization to drive inductive (RL) loads. In this study, we propose a novel control method that overcomes these limitations by enabling the SSMC to achieve relatively high VTRs while driving RL loads with negligible output voltage spikes and without current commutation problems. Further, the proposed control method improves the overall performance by reducing output voltage and source input current total harmonic distortion (THD) and offering soft‐switching at the commutation instances. The rigidity of the proposed control method over the counterpart methods in the literature is verified through simulation and experimental case studies over a wide range of synthesized output frequencies and modulation indexes. A 530‐W laboratory prototype is built for the experimental study. Results demonstrated the ability of the proposed method in enabling the SSMC to drive an RL load without current commutation issues and with mitigated output voltage spikes while achieving relatively high VTRs and suppressing the output voltage and source input current THD.

Design of Ultracompact Gate Driver Integrated With Current Sensor and Commutation Path for a 211-kW Three-Level SiC Aircraft Propulsion Inverter

The aviation industry is increasingly interested in high-efficiency and high-density electric propulsion systems enabled by high-power Silicon Carbide (SiC) modules. However, designing a high-power SiC-based multi-level inverter for aircraft faces several challenges, including high loop inductance, bulky current sensors, high-bandwidth sampling of device current, partial discharge (PD) at high altitudes, and shorter short-circuit withstanding time of SiC MOSFETs. To address these challenges, this paper proposes an ultra-compact multi-functional gate driver that integrates the driving circuit, Rogowski coil current sensor (RCCS), and commutation path for a 211-kW SiC-based three-level (3-L) propulsion inverter. The optimized commutation path and RCCS provide multiple functions, including suppressing overshoot voltage, ultra-fast short-circuit protection, and ac load current sampling. The gate driver’s electric-field can be controlled by PCB-based shielding and shaping to eliminate the PD at high altitudes, thereby improving power density and reducing insulation risk. The paper presents the design methodology of the multi-functional ultra-compact gate-driver and the board-level to system-level common-mode (CM) noise modeling and suppression. The performance of the gate driver is verified on a 211-kW 3-L altitude-ready SiC propulsion inverter system, achieving a power density of 19.5 kW/kg and 7.1 kW/L.

Control Development and Fault Current Commutation Test for the EDISON Hybrid Circuit Breaker

The DC circuit breaker is an indispensable building block for DC network systems. Hybrid circuit breakers that combine mechanical and solid-state switches have more potential to be utilized in DC distribution networks because of their lower conduction losses and fast interrupt speed. The efficient energy DC interrupter with surge protection (EDISON) removes any solid-state circuit in the main current path, thereby substantially reducing the conduction losses during normal operations. However, it requires a dedicated control with fast dynamics because any false triggering of the mechanical switch or solid-state switches of the breaker would lead to a commutation failure and a potential unquenchable arc. This paper proposes a finite-state-machine (FSM) based control scheme that guarantees an accurate and fast control response during a fault event. Due to this fast response requirement, a dual-core-CPU-based control architecture is applied featuring parallel taskings and negligible communication delays between the two cores. Furthermore, a control-law-accelerator (CLA) is employed to further reduce the latency of the program execution by 33%. The controller hardware-in-the-loop (CHIL) model of the EDISON breaker is implemented in OPAL-RT to verify the control scheme and de-risk the prototype test. A fifth-order RLC network is developed to characterize the mechanical switch behavior such that the hybrid circuit model can be simulated in the CHIL solely by circuit components. Finally, the proposed control scheme is implemented and validated in a prototype test with a 3 kA interrupting current and a 60 A/μs current commutation rate.

Detailed Modeling and In-Situ Calorimetric Verification of Three-Phase Sparse NPC Converter Power Semiconductor Losses

The three-phase three-level (3-L) Sparse Neutral Point Clamped Converter (SNPCC) combines a 3-L matrix stage and a three-phase two-level inverter stage to generate 3-L switched output voltages with a reduced transistor count (10 instead of 12 or 18) compared to the classical 3-L NPCC or 3-L active NPCC structure, targeting variable-speed drive systems with low ripple of the motor phase currents or bidirectional three-phase PFC rectifier systems with reduced boost inductor volume. This paper analyzes and experimentally characterizes the performance of an IGBT-based three-phase 3-L SNPCC converter, and describes for the first time a hybrid current commutation effect between inverter-stage diodes and matrix-stage IGBTs that occurs when operating with lower modulation indices and leads to increased switching losses (up to 20%). The proposed new semiconductor loss modeling approach accounts for this effect successfully, which is verified (< 10% error) on an 800V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> , 7.5kW SNPCC hardware demonstrator using a new in-situ calorimetric method that facilitates accurate stage-level semiconductor loss measurements. Heat spreading effects caused by the asymmetrical losses injection and thermal decoupling between two in-situ loss measurement blocks are carefully checked with FEM simulations. Further, an experimental evaluation of common-mode and differential-mode high-frequency voltage-time area ripples (as a generic measure for the required filtering effort) for three typical symmetrical and asymmetrical modulation switching state sequences is provided together with the semiconductor loss characterization. Utilizing a low-switching-loss asymmetric modulation scheme that operates the 3-L matrix stage and the 2-L inverter stage with effective switching frequencies of 16kHz and 5.3kHz, respectively, the 3-L SNPCC demonstrator finally achieves a high rated-power (7.5kW, load current phase shift ϕ = 0) semiconductor efficiency of 98.8%.

Preface

It is our great pleasure to welcome you to the 2022 3rd International Conference on Smart Grid and Energy Engineering (SGEE 2022), held during November 25th-27th, 2022 in Nanjing, China (virtual conference). The conference is a continuation of the international academic conferences in 2020 and 2021, respectively.The primary goal of SGEE 2022 is to provide an international forum for researcher and practitioner to share ideas in all aspect of how to enhance the vocational capability related to Smart Grid and Energy Engineering under the changing and advancing domestic and international situation. Besides, the conference promoted scientific and academic information interchange among all the participants working all over the world. And it will be held every year to make it an ideal platform for people to share views and experiences in related fields.During the conference, we had about 100 participations both as speakers and participants, including researchers, teachers, students, industrial experts, and professionals. To make this conference on schedule, we had a three-part plenary including a keynote speech delivered by resources persons from different parts of China and other countries. All the keynote speakers have delivered expertise lectures by imparting the latest findings from their respective research domains. Among them, Prof. Yifei Wu from Xi’an Jiaotong University, China addressed a keynote speech on the title Research on Economical DC Interruption Technology. In his presentation, the economical DC interruption technology based on arc voltage enhancement was proposed, in which the complex current commutation module was avoided and reduced the cost and volume by more than 30% compared with the existing schemes. Base on the research, a series of 10kV DC circuit breakers based on arc voltage enhancement have been developed and applied in Jiangsu and other DC distribution demonstration projects. It was a wonderful opportunity for all the participants to interact with the experts and specialists to get their advice or suggestions.The proceedings of SGEE 2022 contain quantities of excellent papers grouped by topics. All submissions were performed double blind review to check their quality of content, level of innovation, significance, originality and legibility, covering but not limited to the following topics: Smart Grid Technologies, Power Transmission and Distribution, Renewable Energy, Electricity and Energy System Applications, etc.We would like to express our gratitude to all the participants for their fruitful work and excellent contribution to the success of SGEE 2022. Especially, we appreciate the enormous work of the editorial board and reviewers in the preparation of this volume. Also, our heartfelt thanks and appreciation go to the Editors and Managers, Journal of Physics: Conference Series for their help and kind cooperation during the preparation of the proceedings. We hope you will benefit from all the manuscripts of the proceedings and learn new and novel ideas.The Committee of SGEE 2022List of Committee member is available in this pdf.

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 Study and Implementation of Inductive Power Transfer System Using Hybrid Control Strategy for CC-CV Battery Charging

In this paper, a hybrid control strategy is studied and implemented on an Inductive Power Transfer (IPT) system to simultaneously realize zero-voltage switching (ZVS) and constant current (CC) and constant voltage (CV) battery charging. A steady-state analysis of pulse frequency modulation was conducted, based on the characteristic of voltage gain versus switching frequency, and CC and CV charging modes were promised. The ZVS of the inverter was obtained by satisfying the minimum requirement of full discharge of the junction capacitor on the MOSFETs using a commutation current during the dead-time interval. Two control degrees of freedom are needed to realize the two control targets. This hybrid control strategy adopts a self-oscillating (SO) control to achieve ZVS and phase shift (PS) control and a constant output for the series–series (SS)-compensated IPT system. To validate the hybrid control strategy, a 1.6 kW prototype with 360–440 V input voltage and 250–400 V output voltage was built and the experimental results show that the peak efficiency can reach 96.1%. Compared with the conventional variable frequency (VF) control, the hybrid control method proves that an additional control variable can fulfill the control target in a more flexible manner, which makes the switching frequency close to the resonant frequency during the charging process, minimizing the reactive current in the resonant tank and improving system efficiency.

Magneto-hydrodynamic simulation study of direct current multi-contact circuit breaker for equalizing breaking arc

This work is based on a direct current (DC) natural current commutation topology, which uses load-carrying branch contacts carrying rated current and multiple sets of series arcing branch contacts in parallel to achieve circuit breaking. The proposed topology can meet the new requirements of higher voltage DC switches in aviation, aerospace, energy and other fields. First, a magneto-hydrodynamic arc model is built using COMSOL Multiphysics, and the different arc breaking characteristics of the arcing branch contacts in different gas environments are simulated. Then, a voltage uniformity coefficient is used to measure the voltage sharing effect in the process of dynamic interruption. In order to solve the dispersion of arcing contact action, a structural control method is adopted to improve the voltage uniformity coefficient. The uniform voltage distribution can improve the breaking capacity and electrical life of the series connection structure.

A double-break current injection vacuum DCCB: Principle and analysis

To improve the breaking performances of current injection vacuum DC circuit breaker (DCCB), a double-break current injection DCCB proposed. The opening moments of the two breaks are not simultaneously, one of the breaks is arc breaking, which is used for cut off the fault current, and the other is non-arc breaking, which is used to enhance the transient recovery voltage (TRV) withstand capability. During the interruption process, let the arc-breaking contact first open, the contact starts to separate and produce arcs, then the pre-charged capacitor injects a reverse current to extinguish the arc, meanwhile, the current commutation of non-arc-breaking contact is realized by a coupling inductor. In addition, freewheeling diodes connected in parallel at the contacts to delay the occurrence of transient recovery voltage, thereby further increasing the voltage withstand capability of the CB. The principle and analysis of proposed DCCB scheme are discussed. Finally, the effectiveness of the proposed DCCB scheme is verified by simulation

Different Current Commutation of Three-Phase AC-to-DC Matrix Rectifiers Using Space Vector Modulation

Matrix converter is emerging to be an alternative topology for power converters, drive by persistent cost reduction of silicon devices and the development of reverse blocking IGBTs. One of the major obstacles towards commercial acceptance of this topology has been the commutation of the bi directional switches. A detailed study has been made here to understand the limitations and possible improvement of the existing current commutation techniques in this paper. A universal and synchronous commutation scheme for all the IGBTs is devised so that commutation can smoothly take place as and when required within the minimum possible time depending on the switching time of the IGBT used. The different aspects of this commutation are verified through MATLB simulink. Possibility of step less current commutation is explored.

ПРОЦЕССЫ КОММУТАЦИИ ВЕНТИЛЬНЫХ ТОКОВ ПОЛУПРОВОДНИКОВОГО ВОЛЬТОДОБАВОЧНОГО УСТРОЙСТВА

One of the main tasks of a railway power supply system is the provision of increased traffic volumes especially on direct current railway sections. For this reason the personnel of traction substations uses various means and methods of power supply strengthening including boosters representing two parallel thyristor bridges shunted by diodes. The paper considers three processes of commutation of rectifier currents arising in boosters: between two thyristors, between a shunt diode and thyristors and between thyristors and a shunt diode. The paper presents a detailed mathematical description of these processes. As a result, the authors gained a general formula for calculation of all three angles of commutation, with the use of which the authors have carried out all calculations. Reliability of gained expressions is confirmed on a physical model.