Wide bandgap semiconductors are reshaping the transportation world
(a mixture of AC-DC and DC-AC converters) and other loads are primarily among them. Recent trends in the marine sector are trying to replace AC electrical distribution networks with DC distribution networks. This solution removes the need to synchronize the generators to the AC power distribution, provided they can operate at variable speeds, and achieves fuel savings. On the other hand, it requires the introduction of rectifier circuits (AC-DC converters) between AC generators and the DC power distribution network. Marine propulsion variable speed drives are crucial ship components that must operate with extreme reliability. They are frequently rated from a few watts to a few tens of megawatts. Often, these drives are the most significant power conversion blocks in a ship with AC electrical power distribution. Hence their great efficiency is crucial. Once more, conventional silicon- based power devices are being replaced by SiC and GaN devices, which increase efficiency while reducing size and weight. WBG devices will soon overtake Si- based devices as the industry leader, bringing cutting-edge power electronics system solutions that are impossible with silicon technology. Future fuel-turbine-powered electrical generators will be the prime mover for hybrid and all-
electric avionic propulsion systems. Power electronics will subsequently be used to connect the generator and motor. Very high DC voltage buses are necessary to ensure enough power can be available. These buses can range in voltage from a few kVs for light vehicles to the MV range for airplanes. Moreover, a high DC voltage bus makes it possible to use permanent magnet synchronous machines as generators, which lowers reactive power and the power electronics' rating. The power converters need equipment that can function at high switching frequencies due to the fast generator rotational speed, which results in smaller and lighter filter elements.
temperatures with lower power loss. These characteristics make them particularly well-suited for power electronics used in various applications, including transportation. WBG semiconductors are used in the transportation industry to develop more efficient and reliable electric and hybrid vehicles. The lower power loss of wide bandgap semiconductors allows higher switching frequencies, reducing power electronics' size and weight. This, in turn, can result in greater vehicle range, faster charging times, and improved overall performance. Wide bandgap semiconductors also enable the development of more compact and efficient powertrains, including motor drives and inverters for EVs and HEVs. By reducing the size and weight of these components, vehicle designers can free up space for other components or improve the vehicle’s overall aerodynamics. In addition to electric and hybrid electric vehicles, wide bandgap semiconductors are also used in other transportation forms, such as airplanes and trains. In these applications, the high temperature and high voltage capabilities of wide bandgap semiconductors can improve the efficiency and reliability of power electronics, leading to reduced operating costs and improved safety.
Power losses in the electric rail can be drastically reduced with WBG power electronics. As a result, less energy will be drawn from the grid, and more will be returned via regenerative braking. WBG devices also offer additional benefits that considerably help rail transportation in addition to efficiency increases, such as: ■ Reduced weight has significant impacts on efficiency ■ Higher operating temperature allows for a smaller cooling system ■ Increased switching frequency enables smaller passive dimensions, which lowers the weight of the traction and auxiliary inverters. The inverter and motor can respond to variations in demand more quickly thanks to the higher switching frequency, thus boosting efficiency. Finally, since the higher frequency is less audible and cooling fans may be turned off, railway stops would be less noisy when trains are present.
inverter supplies power for cooling systems, passenger comfort, and other non-movement-related needs. The size of the power electronics within the traction inverter depends on the class of train: ■ Transit trains: 1.2 kV to 2.5 kV ■ Commuter trains: 1.7 kV to 3.3 kV ■ Intercity trains: above 3.3 kV However, most trains use either 3.3 kV or 1.7 kV. Regenerative braking, which returns a part of the electricity to the local grid, rail power distribution system, or energy storage, makes the system more complicated than those in the previously stated applications. Regenerated energy must be stored or used immediately; otherwise, it is lost.
Bipolar Si-based IGBTs and freewheeling diodes, traditionally used in power modules for railway traction applications, can be replaced by unipolar SiC-based MOSFETs and diodes, thus increasing the switching frequency and power density. Conduction and switching losses must be decreased, and the maximum junction temperature must be raised to reduce the weight and volume of the power electronic equipment used in
Silicon carbide is the most promising semiconductor
device to meet all requirements while ensuring high conversion efficiency. For aircraft in the lower power range, newly created 3.3 kV and 6.5 kV SiC MOSFET devices are of significant interest. They can also be employed in modular power converter topologies to meet larger aircraft's higher voltage/power requirements.
railway traction applications. For the widely used bipolar
silicon power devices, increasing conduction losses and decreasing switching losses have the opposite effects. A unipolar device does not experience the trade-off between the conduction and switching losses as bipolar devices do. As a result, switching losses could be reduced while minimizing conduction losses.
Marine and aviation applications
Conclusion
Power electronics innovations have benefited the marine sector for a long time. On the ship, medium voltage AC level electricity from synchronous generators powered by diesel engines is supplied to various loads. Propulsion drives
Wide bandgap semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), offer several advantages over traditional semiconductors in their ability to handle high voltages and
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