Yinye Yang

Making the Case for Electrified Transportation

In order to achieve lower fuel consumption and less greenhouse gas (GHG) emissions, we need higher efficiency vehicles with improved performance. Electrification is the most promising solution to enable a more sustainable and environmentally friendly transportation system. Electrified transportation vision includes utilizing more electrical energy to power traction and nontraction loads in the vehicle. In electrified powertrain applications, the efficiency of the electrical path, and the power and energy density of the components play important roles to improve the electric range of the vehicle to run the engine close to its peak efficiency point and to maintain lower energy consumption with less emissions. In general, the electrified powertrain architecture, design and control of the powertrain components, and software development are coupled to facilitate an efficient, high-performance, and reliable powertrain. In this paper, enabling technologies and solutions for the electrified transportation are discussed in terms of power electronics, electric machines, electrified powertrain architectures, energy storage systems (ESSs), and controls and software.

Double-Rotor Switched Reluctance Machine (DRSRM)

With the era of modern vehicle electrification, electric machines with high traction torque-speed output and compact volume are highly desired. This paper presents a family of switched reluctance machine configurations that are composed of double rotors and one stator integrated in one machine housing. The machines are potentially more compact and lower cost, while providing two independent mechanical outputs suitable for hybrid electric vehicle transmissions. The detailed design process of a double-rotor switched reluctance machine (DRSRM) is presented, comprising of analytical calculations, finite-element field analysis, and full-drive system simulation. Additionally, some optimizations are applied to maximize the machine performance and minimize the machine weight and volume. A scaled prototype machine is designed and built according to chosen vehicle drive cycles to evaluate and validate the DRSRM prototype.

State-of-the-art electrified powertrains - hybrid, plug-in, and electric vehicles

Automotive electrification has become the centre of current transportation technology especially in the age of surging petroleum fuel prices and rising social awareness of vehicle emissions. A range of electrified powertrains from micro hybrid to full electric have been implemented in a wide variety of vehicle platforms from subcompacts to heavy-duty trucks and buses. The main focus of this paper is to comprehensively review the state-of-the-art electrified powertrains that have been developed and commercialised in the North American automotive industry. Vehicles are categorised based on different powertrain configurations and electrification levels. The powertrain structure and operating modes are also analysed in detail. In addition, a comprehensive database of electrified powertrains and their components is created. Electrified powertrains and the corresponding conventional powertrains are compared in terms of vehicle efficiency, powertrain complexity, and pump-to-wheel CO2 emissions.

Traction inverters in hybrid electric vehicles

Traction inverters are of critical importance in the propulsion systems of hybrid electric vehicles (HEVs). This paper focuses on major design aspects of HEV traction inverters comparing different types of the existing inverter topologies, reviewing the power specifications in commercialized hybrid electric vehicles, and discussing the advanced power module packaging technology. In addition, related applications of the wide bandgap power devices are reviewed. This paper also gives the overall overview of the current traction inverters and future trends for automotive applications.

Integrated electro-mechanical transmission systems in hybrid electric vehicles

Hybrid electric vehicles are emerging as a practical solution for meeting increasingly more stringent governmental standards for fuel economy and emissions. In order to improve performance, increase efficiency, and reduce costs, there is a trend toward more integrated electro-mechanical transmission systems for advanced hybrid powertrains. This paper primarily focuses on the state-of-the-art electro-mechanical integration of hybrid transmission systems and presents a comprehensive review of various integrated powertrains including the power-split, two-mode hybrid transmission systems, and the electric variable transmission. Fundamental principles and mechanisms of operation for these integrated electro-mechanical transmission systems are presented as well.

Integrated Electromechanical Double-Rotor Compound Hybrid Transmissions for Hybrid Electric Vehicles

Integrated hybrid transmissions serve as the key component in hybrid electric vehicles (HEVs). This paper reviews several technologies of the electromechanical integration of advanced hybrid transmission systems. Detailed configurations, fundamentals of operating principles, and various operating modes were comprehensively explained and analyzed. Combining the merits, an integrated electromechanical double-rotor compound hybrid transmission that is potentially more compact and has better performance is proposed. Detailed operation modes are compared, and functions and cooperation between integrated components are illustrated. As the core component of the integrated transmission, the double-rotor electric machine is studied via drive-cycle analyses, and a scaled-down prototype is built according to the drive-cycle analysis results. Test results successfully validate the design and simulation process.

Design and Comparison of Interior Permanent Magnet Motor Topologies for Traction Applications

Traction motors play a critical role in electrified vehicles, including electric, hybrid electric, and plug-in hybrid electric vehicles. With high efficiency and power density, interior permanent magnet (IPM) synchronous machines have been employed in many commercialized electrified powertrains. In this paper, three different IPM rotor design configurations, which have been used in electrified powertrains from Toyota, Nissan, and General Motors, are comparatively investigated. Each topology is redesigned and improved to meet new design requirements based on the same constraints. The designed motors are then compared and comprehensively evaluated for motor performance, torque segregation, demagnetization, mechanical stress, and radial forces. The results suggest that the single V-shaped configuration achieves the best overall performance and is thus recommended as the best candidate.

Modeling and analysis of core losses of an IPM machine for online estimation purposes

Online estimation of losses is important to improve control, operation and monitoring of electrical machines. This paper focuses on investigation of iron losses using a magnetic circuit model for its accuracy and adaptability to online estimation purposes. A customized magnetic circuit of an IPM machine is proposed that captures slotting, non linearity, cross saturation and localized effect of flux bridges. A technique is presented to compute the alternating stator and rotor flux from the static magnetic circuit. The required computations are reduced introducing pseudo mmf sources that avoid solving magnetic circuit at several rotational steps. The stator and rotor core losses are found corresponding to each harmonic component of alternating flux density. The results are validated with Finite Element analysis with good correlation.

Hybrid electric locomotive powertrains

With the increasing awareness of fuel consumption and combustion engine exhaust emissions, more electrified locomotives emerge as promising solutions to fulfill the new requirements of being “Green”. This paper aims at reviewing the present situation and development of hybrid electric locomotive powertrains. The present diesel-electric locomotive powertrains, motor-assist locomotive powertrains as well as their alternators and traction motors are reviewed. Various other locomotive hybrid powertrains are also presented with the future trends discussed.

Coupled switched reluctance machine modeling and simulations

The double saliency and high saturation levels in switched reluctance machines (SRM) pose difficulties in modeling and analyzing the machines. Current distortions due to less model fidelity or machine drive current controls result in variations in simulation accuracy. This paper introduces coupled SRM drive modeling and simulation process that takes account for the machine, drive and loads characteristics so that all these variations are considered in the design process. Three modeling techniques have been presented and explained in detail. The simulation results are compared between the models. Good agreements have been achieved and the accuracy of the models and simulations has been confirmed. The simulations are also validated by experimental results taken from a prototype SRM machine.