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Power Electronic Converters to Drive Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
If a converter is capable of applying more than two voltage levels, it is called a multi-level converter. As compared to conventional two-level converters, multi-level converters have several advantages, such as lower magnitude of current ripple, lower power losses at high switching frequency, lower common-mode voltage, and lower electromagnetic interference (EMI) [2]. Due to these advantages, multi-level converters are popular in medium voltage applications.
Experimental Verification of a New Scheme of MLI Based on Modified T-Type Inverter and Switched-Diode Cell with Lower Number of Circuit Devices
Published in Electric Power Components and Systems, 2021
Bidyut Mahato, Saikat Majumdar, Kartick Chandra Jana, Parashuram Thakura, Dusmanta Kumar Mohanta
In the 1960s, DC/AC converters were not widespread for industrial applications due to the fact that the vacuum tubes and gas-filled tubes, especially thyratron, were used as power switches in inverter circuits, which can be operated only at low switching frequencies [1–4]. The concept of a multi-level inverter was introduced in 1975. Subsequently, these are highly regarded by researchers as opposed to traditional two-level inverters due to their high power efficiency, lower dv/dt pressure, lower switching loss, lower harmonic content and low electromagnetic interference [5, 6]. Multi-level inverters have recently gained tremendous importance for high and medium voltage applications in the power industry. For high-power applications, non-conventional energy sources such as photovoltaic cells, wind farms, and fuel cells could simply be interfaced with a multi-level converter system [7, 8].
A Capacitor Voltage Balancing Scheme for a Single-Phase Cascaded H-Bridge STATCOM
Published in Electric Power Components and Systems, 2018
Yarlagadda Srinivasa Rao, Mukesh Kumar Pathak
The static synchronous compensator (STATCOM) is used in the transmission lines to regulate the line voltages and to increase the active power flow. The voltage source converter (VSC) suitable for STATCOM is realized by (i) Two level converter and a line frequency transformer, (ii) multi-pulse converters, and (iii) multi-level converters. The line frequency transformer is costly, bulky, and lossy, so this type of converter is not preferred for medium voltages. The multi-pulse static converter can be used for shunt compensation [1] but due to the requirements of the complex phase shifting transformer, the multi-pulse converter is also less preferred. Owing to the disadvantages of transformers, the multi-level converters [2–28] are preferred for the medium voltage and high power applications. The basic topologies in multi-level converters are diode-clamped converters, flying capacitors converters, and cascaded H-bridge (CHB) converters. In realizing the shunt compensators, generally CHB multi-level converters are used [2–28]. The major advantage of cascaded multi-level converter is its modular structure, which is easy for both maintenance as well as future extension.
Distributed Wind Energy Conversion System Interface to the Grid Using Cascaded Multi-Level Converter
Published in IETE Journal of Research, 2018
Chandra Sekhar Nalamati, Paulson Samuel, Rajesh Gupta
The three modular structured PRs act as three separate equal dc sources. These three separate dc sources provide dc power to three H-bridge units of the seven-level cascaded multi-level converter. In this configuration, the IGBT switch rated 1.7 kV, 500 A, easily handle the individual PR ratings of (1.35 kV, 750 kW), with the help of a suitable three-phase transformer. Also, there is no real need of additional dc–dc converter to control the common dc-link voltage which was strictly required in the configuration shown in Figure 2. The equal rated cascaded H-bridges provide equal distribution of the switching stress and power among all the H-bridge cells of the seven-level converter. It is easier to manage same heat dissipation due to the converter losses in a number of H-bridges. The total power loss is easier to estimate due to the fixed switching frequency operation of the converter [8] and thus thermal management is easier. The transformer boosts up the output of the low voltage converter to the 11 kV grid.