Search

Hybrid energy storage systems are widely used in electric vehicles and other fields. Focused on the problem of lithium‐ion battery life attenuation caused by high‐frequency components in load power requirements, a closed‐loop Haar wavelet power splitting method is proposed. First, the circuit structure of the hybrid energy storage system is introduced. Then, based on the analysis of the Haar wavelet transform, the Haar wavelet power splitting method, and closed‐loop control algorithm are proposed. On one hand, the Haar wavelet power splitting method is responsible for allocate the high‐frequency and low‐frequency components of the power demand to ultra‐capacitor and lithium‐ion battery, respectively; on the other hand, a closed‐loop controller is proposed to regulate the output current of the lithium‐ion battery dynamically to maintain the stability of the DC bus voltage. Finally, experiments were conducted under CLTC‐P driving cycle. The experimental results show that the proposed closed‐loop Haar wavelet power splitting method can control the maximum deviation of DC bus voltage within 1.28%, while effectively avoiding the impact of high‐frequency components on the life of lithium‐ion batteries. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Hybrid direct current circuit breakers (DCCBs) have become prominent because of their low on‐state power dissipation and small arc erosion compared with conventional semiconductor and mechanical circuit breakers (CBs). After a fault occurs in a DC circuit, the current commutates from the mechanical contacts to the semiconductor devices of the hybrid DCCB, and finally, the current is interrupted by the semiconductor devices. Thus, a low turn‐on voltage or a low on‐state resistance of the devices is needed to reduce the commutation time and power dissipation of the current interruption. This paper presents a comparison of DCCB performances metrics, such as the maximum interruption current, power dissipation, and junction temperature, using a silicon carbide metal‐oxide‐field‐effect transistor (SiC‐MOSFET) and silicon insulated‐gate‐bipolar transistor (Si‐IGBT) module. An interruption of 1.1 kA was achieved in 4.3 ms using the SiC‐MOSFET module of which rated current was 444 A. The junction temperature after the interruption was determined to be 275°C, which exceeded the maximum junction temperature of 175°C. In the case of the Si‐IGBT module of which rated current was 1110 A, the maximum interrupting current was limited to 900 A; however, the maximum junction temperature was 41°C. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Multi‐port hybrid DC circuit breakers (MP‐HCBs) are rapidly developing due to their obvious advantages in economy compared to traditional two‐port hybrid circuit breakers (HCBs). However, most of the existing MP‐HCB topologies do not have the current‐limiting capability, and a large number of insulated‐gate bipolar transistors (IGBTs) are still needed in their main breakers. In response to the problems, a multi‐port current‐limiting hybrid DC circuit breaker (MP‐CLHCB) based on thyristors is proposed in this paper. MP‐CLHCB uses low‐cost thyristors instead of IGBTs, and suppresses the rise of fault current through current‐limiting branch. In an attempt to prevent the MP‐CLHCB from reclosing in a permanent fault and causing damage to the DC grid again, an adaptive reclosing scheme is also proposed. In this paper, the topology, operation stages, theoretical derivation, and parameter design of the MP‐CLHCB are provided. Finally, the performance of the MP‐CLHCB is verified and compared through simulations in PSCAD/EMTDC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A hybrid direct current circuit breaker consisting of electrical contacts connected in parallel with a silicon carbide metal oxide semiconductor field‐effect transistor semiconductor device is capable of operating with low energy loss and high short‐circuit tolerance. It features a short‐duration arc discharge during current commutation; however, how the arc affects the dielectric strength between the contacts is not yet clear. This study conducts a quantitative evaluation of the dielectric strength after a short‐duration arc commutation. It is shown that the dielectric strength decreases after the arc commutation, and the breakdown electric field decreases as the arc duration increases. These results suggest that the existence of metal vapor and an increase in contact erosion caused by the commutation arc lower the dielectric strength of the electric contacts, in addition to the known effects of temperature rise of the contact surface and the air between contacts. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

To achieve current balance between parallel‐connected insulated gate bipolar transistors (IGBTs) of a DC microgrid hybrid circuit breaker (DC MHCB), it is a simple and effective method to add impedance in parallel‐connected IGBTs, but this will also affect the vacuum arc commutation of the DC MHCB. The focus of this paper is the effects of adding impedance on vacuum arc commutation characteristics. By constructing a simplified model of vacuum arc commutation in the case of adding impedance, the effect of adding impedance on vacuum arc commutation is theoretically derived. The test circuit of vacuum arc commutation is established, and the effect of adding impedance on vacuum arc commutation in the presence or absence of the externally applied transverse magnetic field (TMF) is investigated using the electrical measure. The theoretical formula and related formulas of the effect of adding impedance on the duration of vacuum arc commutation are obtained. A method combining adding impedance and an externally applied TMF is proposed. The constraint formula for adding impedance during vacuum arc commutation is obtained. The main factors that limit the value of adding impedance are obtained. Research on the effect of adding impedance on vacuum arc commutation characteristics can provide theoretical guidance for the application of the method of adding impedance in a DC MHCB. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper describes the detailed design of the quench protection circuits (QPCs) for the superconducting toroidal field (TF) and poloidal field (PF) magnets of the satellite tokamak JT-60SA, which will be installed in Naka, Japan. The nominal currents to be interrupted and the maximum reapplied voltages are 25.7 kA and 2.8 kV for the TF QPCs and 20 kA and 5 kV for the PF QPCs. The innovative solution proposed in the QPC design is based on a hybrid circuit breaker (CB) composed of a mechanical bypass switch for conducting the continuous current, in parallel to a static CB for current interruption. The main choices of the final design are presented and discussed, either to confirm or to update and complete the study performed at the conceptual design level. [ABSTRACT FROM PUBLISHER]