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78 results on '"Na, Risha"'

6. Simple Switching Strategies for dv/dt Reduction in SiC-Device-Based Modular Multilevel Converters.

Author

Li, Xiao, Liu, Rui, Ke, Ziwei, Pan, Jianyu, Hu, Boxue, Na, Risha, Xu, Longya, and Wang, Jin

Abstract

This article presents two simple strategies for output dv/dt reduction in modular multilevel converters through coordination of the switching transients of the submodules. The first method is achieved by adding a delay time between the switching transients of two submodules, which would be switched simultaneously in regular switching strategies of modular multilevel converters. The second method is to inject a reverse dv/dt to the converter's output by switching redundant submodules. Both methods do not affect the switching speeds of the semiconductor devices and require no additional hardware components. They can be applied with different modular multilevel converters modulation strategies. Circuit analysis of the proposed methods and their effects on the converter operation are presented. Simulation and test results of a 1.7-kV SiC-device-based modular multilevel converter are provided to validate the circuit analysis. It is shown that the proposed methods can reduce the converter's output dv/dt to half of a single switching device's dv/dt. [ABSTRACT FROM AUTHOR]

Published
2023
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33. Intelligent fuzzy energy management research for a uniaxial parallel hybrid electric vehicle

Author

Meng Dawei, Na Risha, Zhang Yu, and Zhou Meilan

Subjects
Engineering, business.product_category, General Computer Science, business.industry, 020209 energy, Automotive industry, 020302 automobile design & engineering, 02 engineering and technology, Fuzzy control system, computer.software_genre, Fuzzy logic, Simulation software, State of charge, 0203 mechanical engineering, Control and Systems Engineering, Control theory, Electric vehicle, 0202 electrical engineering, electronic engineering, information engineering, Torque, Electrical and Electronic Engineering, business, computer
Abstract

An intelligent fuzzy control strategy is proposed for parallel hybrid electric vehicle.The membership functions of fuzzy controller are optimized by genetic algorithm.Electric vehicle co-simulation technology is a good application. In this paper, an intelligent fuzzy logic control strategy optimized by genetic algorithm (GA) has been proposed for uniaxial parallel hybrid electric vehicle (PHEV), in the fuzzy controller, the ratio between the motor target torque and the total demand torque is the first input variable, and the state of charge (SOC) of the battery is the second input variable. The torque distribution coefficient between the engine and the motor is as the output variable. The proposed strategy is compared to the electric auxiliary control strategy. The whole vehicle is modeled based on experimental data and the strategy is verified in automotive simulation software ADVISOR, the results show that the proposed control strategy can reduce fuel consumption, reduce emissions, ensure balanced charging and discharging of the battery, effectively avoid the production of the engine peak torque, and improve the overall performance of the vehicle. Display Omitted

Published
2017

46. Hardware design of a 1.7 kV SiC MOSFET based MMC for medium voltage motor drives

Author

Li, He, primary, Potty, Karun, additional, Ke, Ziwei, additional, Pan, Jianyu, additional, Chen, Yingzhuo, additional, Zhang, Fan, additional, Sabbagh, Muneer Al, additional, Perdikakis, Will, additional, Li, Gengyao, additional, Ye, Xi, additional, Na, Risha, additional, Zhang, Julia, additional, Xu, Longya, additional, and Wang, Jin, additional

Published
2018
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49. An Ultraefficient DC Hybrid Circuit Breaker Architecture Based on Transient Commutation Current Injection

Author

Zhou, Yuanfeng, Feng, Yanjun, Shatalov, Nikolay, Na, Risha, and Shen, Z. John

Abstract

Protection against circuit faults represents a major technical challenge in the emerging dc transmission and distribution power networks. A popular prior-art dc hybrid circuit breaker (HCB) using a series load commutation switch (LCS) offers an excellent solution with arcless operation but suffers from a high conduction power loss associated with the LCS. This article proposes a new HCB architecture that relies on a switching-mode transient commutation current injector (TCCI) circuit instead of the LCS. The TCCI in the electronic path remains in a standby mode with near-zero power loss under normal conditions, but can rapidly generate a pulse current matching the fault current, and therefore facilitate current commutation from the mechanical to the electronic path. It completely eliminates the conduction power loss associated with the LCS, and delivers ultrahigh transmission efficiency. The TCCI circuit provides a near-zero voltage and a small high-frequency ac ripple current condition for the mechanical contacts to separate arclessly. A 600-V/20-A HCB prototype based on a two-phase current source buck converter topology and a high-voltage vacuum relay has experimentally validated the HCB concept, and demonstrated a mechanical to electronic commutation time of $7.2~\mu \text{s}$ , a total active response time of $310~\mu \text{s}$ , and a peak interrupted fault current of 89 A at a dc bus voltage of 400 V. The new HCB architecture can be applicable in medium voltage direct current (MVDC) (>5 kV) and high voltage direct current (HVDC) (>100 kV) applications as well.

Published
2021
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