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Until recently, electrified aircraft propulsion (EAP) technology development has been driven by the dual objectives of reducing greenhouse gas (GHG) emissions and addressing the depletion of fossil fuels. However, the increasing severity of climate change, posing a significant threat to all life forms, has resulted in the global consensus of achieving net-zero GHG emissions by 2050. This major shift has alerted the aviation electrification industry to consider the following: What is the clear path forward for EAP technology development to support the net-zero GHG goals for large commercial transport aviation? The purpose of this paper is to answer this question. After identifying four types of GHG emissions that should be used as metrics to measure the effectiveness of each technology for GHG reduction, the paper presents three significant categories of GHG reduction efforts regarding the engine, evaluates the potential of EAP technologies within each category as well as combinations of technologies among the different categories using the identified metrics, and thus determines the path forward to support the net-zero GHG objective. Specifically, the paper underscores the need for the aviation electrification industry to adapt, adjust, and integrate its EAP technology development into the emerging new engine classes. These innovations and collaborations are crucial to accelerate net-zero GHG efforts effectively.

The deployment of intelligent transportation is still in its early stages and there are many challenges that need to be addressed before it can be widely adopted. Autonomous vehicles are a class of intelligent transportation that is rapidly developing, and they are being deployed in selected cities. A combination of advanced sensors, machine learning algorithms, and artificial intelligence are being used in these vehicles to perceive their environment, navigate, and make the right decisions. These vehicles leverage extensive data sourced from various sensors and computers integrated into the vehicle. Hence, massive computational power is required to process the information from various built-in sensors in milliseconds to make the right decision. The power required by the sensors and the use of additional computational power increases the energy consumption, and, hence, could reduce the range of the autonomous electric vehicle relative to a standard electric car and lead to additional emissions. A number of review papers have highlighted the environmental benefits of autonomous vehicles, focusing on aspects like optimized driving, improved route selection, fewer stops, and platooning. However, these reviews often overlook the significant energy demands of the hardware systems—such as sensors, computers, and cameras—necessary for full autonomy, which can decrease the driving range of electric autonomous vehicles. Additionally, previous studies have not thoroughly examined the data processing requirements in these vehicles. This paper provides a more detailed review of the volume of data and energy usage by various sensors and computers integral to autonomous features in electric vehicles. It also discusses the effects of these factors on vehicle range and emissions. Furthermore, the paper explores advanced technologies currently being developed by various industries to enhance processing speeds and reduce energy consumption in autonomous vehicles.

The current trend in distributed electric aircraft propulsion systems is to utilize the DC bus system at higher voltage levels than conventional aircraft systems. With Boeing and Airbus utilizing the +/−270 V bipolar DC bus system, the research on high-voltage systems is increasing gradually, with voltage levels ranging from 1 to 10 kV systems or +/−0.5 to +/−5 kV DC bus systems. These voltage levels present considerable challenges to the distributed electric aircraft propulsion systems. In addition to partial discharge effects, there are other challenges, particularly the challenge associated with effectively limiting short-circuit fault currents due to the low cable impedance of the distribution system. The cable impedance is a significant factor that determines the fault current during fault conditions. Due to the low impedance, there is a sharp increase in fault current, necessitating an enhanced protection strategy, which ensures that the system is adequately protected. This paper introduces a coordinated protection strategy specifically designed for distributed electric aircraft propulsion systems to mitigate or prevent short-circuit faults. The proposed algorithm utilizes an I2t-based strategy and the current-limiting-based strategy to protect the system from short-circuit faults and overload conditions. Redundant backup protection is also included in the algorithm in case the circuit breaker fails to operate.

In electric vehicle fast charging systems, it is important to minimize the effect of fast charging on the grid and it is also important to operate the charging system at high efficiencies. In order to achieve these objectives, in this paper, a sinusoidal half-wave DC current charging protocol and a sinusoidal half-wave pulsed current charging protocol are proposed for the fast charging of Li-ion batteries. A detailed procedure is presented for implementing the following proposed methods: (a) a pre-defined half-sine wave current function and (b) a pulsed half-sine wave current method. Unlike the conventional full-wave sinusoidal ripple current charging protocols, the proposed study does not utilize any sinusoidal full-wave ripple. The performance of these new charging methods on Ni-Co-Al-type Li-cells is studied and compared with the existing constant current and positive pulsed current charging protocols, which have been discussed in the existing literature. In addition, the changes in the electrochemical impedance spectrograph of each cell are examined to study the effects of the applied charging methods on the internal resistance of the Li cell. Finally, the test results are presented for 250 life cycles of charging at 2C (C: charging rate) and the degradation in cell capacities are compared among the four different methods for the Ni-Co-Al-type Li cell.

Permanent magnet (PM) motors are gaining prominence in subsea applications such as drilling, pumping, and boosting for oil and natural gas extraction. These motors are gradually replacing traditional induction motors. However, starting and operating PM motors at low speeds under heavy loads poses significant challenges. This is because of unknown initial rotor positions and resistive voltage drops due to the presence of a sinewave filter, transformer, and long cable. An unknown rotor position may result in temporary reverse speed, which may cause a loss of synchronism; therefore, initial rotor position estimation is preferable. Additionally, addressing the voltage drop issue requires careful voltage compensation to avoid transformer core saturation. In this paper, an enhanced V/Hz starting of a PM motor is proposed with initial position detection (IPD) and voltage compensation to start the motor reliably with a heavy load. The proposed control method is verified with controller hardware in the loop (C-HIL) real-time simulation using a Typhoon HIL-604 emulator and a Texas Instruments TMS320F28335 digital signal processor (DSP) control card.

Abstract In this paper, an H‐type electric/hybrid electric aircraft propulsion architecture is proposed to address the issues associated with the radial electric propulsion architecture. In a radial architecture, a fault on the main bus or failure of the generator leads to shut down of all the propulsion motors in that channel, thus increasing the burden on the remaining motors to maintain the power required by the aeroplane. As a result, it is necessary to oversize the motors for the purpose of compensating for the loss of other motors. To mitigate these issues, a new H‐type architecture is introduced to isolate the particular faulty section while still maintaining power flow to the remaining healthy motors. The proposed architecture minimises the oversizing of various components in the system as compared to radial propulsion architecture. The sizing of components and the amount of overall mass reduction is discussed by using the proposed architecture. Typhoon Hardware in the Loop platform is used to validate the performance of both the architectures for faults at different locations, and the results are presented.

Subsea oil and gas (O&G) exploration demands significantly high power to supply the electrical loads for extraction and pumping of the oil and gas. The energy demand is usually met by fossil fuel combustion-based platform generation, which releases a substantial volume of greenhouse gases including carbon dioxide (CO2) and methane into the atmosphere. The severity of the resulting adverse environmental impact has increased the focus on more sustainable and environment-friendly power processing for deepwater O&G production. The most feasible way toward sustainable power processing lies in the complete electrification of subsea systems. This paper aims to dive deep into the technology trends that enable an all-electric subsea grid and the real-world challenges that hinder the proliferation of these technologies. Two main enabling technologies are the transmission of electrical power from the onshore electrical grid to the subsea petroleum installations or the integration of offshore renewable energy sources to form a microgrid to power the platform-based and subsea loads. This paper reviews the feasible power generation sources for interconnection with subsea oil installations. Next, this interconnection’s possible power transmission and distribution architectures are presented, including auxiliary power processing systems like subsea electric heating. As the electrical fault is one of the major challenges for DC systems, the fault protection topologies for the subsea HVDC architectures are also reviewed. A brief discussion and comparison of the reviewed technologies are presented. Finally, the critical findings are summarized in the conclusion section.

Torque smoothness is an essential requirement for high-performance motor drive applications. Synchronous reluctance machines (SyRM) have high torque ripple due to non-linear magnetic circuit and saturation. Typically, in Permanent magnet machines the active torque ripple compensation is achieved by injecting a compensating ripple current in the q-axis. For SyRM, the current injection method for active torque ripple cancellation can be used in both the d-axis and q-axis. However, the saturation of the motor parameters with the changing current can result in varied performance between the two methods. This paper evaluates the effectiveness of both of these methods for torque ripple cancellation. For evaluation, the impact of parameter saturation with ripple current injection on the d-axis and the q-axis is studied. The mathematical conclusions obtained are evaluated by both the simulation and the experimental results performed on a 4 pole 1200W Synchronous reluctance machine.

This article proposes a multilevel inverter topology with single dc-link and series-connected capacitors as stacked voltage sources for multilevel voltage generation. The voltage deviation of a dc-link capacitor will occur whenever a phase terminal connects to the balanced neutral points (NPs: terminal joints of dc-link capacitors). On the contrary, if the voltage of a dc-link capacitor deviates from the nominal voltage, the same phase currents can be utilized to balance these NPs. This new technique is being proposed for the first time in the literature. Any voltage disturbance of the dc-link capacitors is balanced using the motor phase currents, irrespective of load power factor and modulation indices. For the balanced NPs, whenever a phase connects to an NP, the other phase terminal tapping positions are varied on the dc link to establish $i_{A}+i_{B}+i_{C}=0$ for that NP. The pole voltage level variation at motor phase terminals is undisturbed by adding extra cascaded H-bridges (CHBs) at each phase leg. The voltages of CHB capacitors are controlled conventionally by inverter pole voltage redundancies. The detailed experimental results for open-loop V/f and closed-loop field-oriented control on an induction motor are presented using a nine-level laboratory prototype.

With the integration of renewable energy sources into the power grid, a number of power electronic converters need to be connected together in parallel. Due to this interconnection among the power converters with a common DC bus, the equivalent impedance of the DC network, i.e., DC network impedance (DCNI) of these parallel converters, may vary and can cause oscillations in the DC link voltage (DCLV). In the literature, impedance models of grid-tied converters (GCs) based on the AC side are well reported without including these variations in DCNI. In addition, the dynamics of a phase-locked loop (PLL) play a significant role in GC system stability. To evaluate these stability issues, this paper proposes small signal impedance models viewing from the DC side of a three-phase GC operating under different control modes considering the PLL dynamics and the DCNI variations. Using the proposed DC impedance models (DCIM), DCLV stability analysis is evaluated for a GC. It is verified through bode plots that the interaction between the proposed DCIM and DCNI leads to unstable operation of the closed-loop converter near the PLL bandwidth when the phase difference between DCIM and DCNI is more than 180 degrees. Finally, the analytically developed models are validated using hardware in-the-loop (HIL) testing.