Modular Multilevel Converter (MMC) for Transportation Traction Applications πŸ—“

— Medium Frequency Transformer, weight of magnetics, efficiency, electric railway application, topologies …

-- IEEE Transportation Electrification Committee (on the Internet) Map

Webinar Date: Tuesday, October 17, 2017
Time: 8:00 AM (PDT)
Speaker: Dr. Luiz Henrique Barreto, Universidade Federal do CearΓ‘
Location: on the Web
Cost: none
RSVP: required
Event Details & Registration:

Summary: Since its initial conception, the transformer has been used in the most diverse applications where insulation and adaptation of voltage levels are demanded. In fact, this device is widely employed either directly or indirectly in all electrical engineering fields due its simple design for distinct power and voltage conversion levels. More specifically, the power transformer ensures the aforementioned characteristics in power systems applications, such as: ac power energy transmission and distribution, as well as medium-voltage machine drives. However, such applications are typically based on a bulky low-frequency device called Line Frequency Transformer (LFT).
Moreover, many applications normally use oil inside the LFTs for cooling and insulation purposes, which has direct impact on weight and volume and implies serious environmental issues. Another drawback lies in the low efficiency of LFTs, since they are typically designed with high current densities (as less copper is required) and operate at heavy load conditions that may result in operation with efficiency of 90%. In order to overcome such bottlenecks, many recent studies have tried to replace the conventional LFT for a power converter using a Medium Frequency Transformer (MFT) with operating frequency around thousands of hertz, thus reducing the intrinsic size and weight of its magnetics.
Such reduction is a must in medium-voltage machine drives, more particularly in electric railway application, since a more compact propulsion system is a requirement, resulting in the improvement of the transformer efficiency and reduction of the requested power with the same cargo capability. This advantage is especially desired in Electric Multiple Units (EMU) where the propulsion system is distributed among the locomotive’s cars.
Besides the voltage and weight reduction, the approach using MFTs must ensure harmonic mitigations, power factor correction, and fault suppression, among other functionalities.
This talk will present several SST topologies. Since all configurations must deal with high voltage levels due the innate SST propose, designers must choose the technology that best fits in their applications, considering the particular characteristics.