This paper presents a new electricity power generation architecture for the engine system of more electric aircraft (MEA). A starter/generator (SG) is connected to highpressure (HP) spool, and a generator is attached to low-pressure (LP) spool. Their outputs supply a common DC bus. A back-toback (B2B) converter is connected between the AC sides of two generators. There are two main contributions of the proposed idea. First, some power can be transferred from LP shaft to HP shaft via the B2B converter, which will benefit to reduce the fuel consumption and increase compressor surge margin of the engine. Second, the HP starter/generator could operate in a high speed without flux weakening, hence the magnitude of stator current will largely decrease when output same active power, leading to the reduction of overall power losses. Modeling and control method design are illustrated. The effectiveness of proposed power generation architecture, engine performance improvement and power loss reduction are verified.

The energy management strategy of a hybrid-electric aircraft is coupled with the design of the propulsion system itself. A new design space exploration methodology based on Set-Based Design is introduced to analyse the effects of different strategies on the fuel consumption, NOx and take-off mass. Probabilities are used to evaluate and discard areas of the design space not capable of satisfying the constraints and requirements, saving computational time corresponding to an average of 75%. The study is carried on a 50-seater regional turboprop with a parallel hybrid-electric architecture. The strategies are modelled as piecewise linear functions of the degree of hybridisation and are applied to different mission phases to explore how the strategy complexity and the number of hybridised segments can influence the behaviour of the system. The results indicate that the complexity of the parametrisation does not affect the trade-off between fuel consumption and NOx emissions. On the contrary, a significant trade-off is identified on which phases are hybridised. That is, the least fuel consumption is obtained only by hybridising the longest mission phase, while less NOx emissions are generated if more phases are hybridised. Finally, the maximum take-off mass was investigated as a parameter, and the impact to the trade-off between the objectives was analysed. Three energy management strategies were suggested from these findings, which achieved a reduction to the fuel consumption of up to 10% and a reduction to NOx emissions of up to 15%.

Due to substantial use of gas turbines and their highly dynamic behavior, they have a profound impact on electrical grid. Although the control philosophies of various turbines are almost the same, there are some nuances in governor systems. As long as these details affect system response in extremely dynamic phenomena such as load rejection, they should be included in models. In this paper, the governor system is subjected to careful scrutiny; tasks of controllers are classified schematically and some special features such as back-tracing and feed-forward are discussed. The turbine is also modeled and a function is developed to calculate turbine exhaust gas temperature. The proposed governor-turbine model is validated by test results and a comparative analysis shows that the back-tracing method prevents wind-up phenomenon and the feed-forward method improves stability and response time.

Novel propulsion systems have been studied in literature to reduce aircraft emissions with hydrogen or other electrical energy sources. Hybrid Electric Propulsion (HEP) system consists of electric machines as an alternative way to provide power for propulsion resulting in the reduction of aircraft fuel consumption. While reduction of emission is the main driver of new HEP designs, aircraft noise reduction and performance improvement will also need to be investigated. Much quieter electrified aircraft than conventional aircraft is explored with considering the benefits of coupled design between the propeller and electric machines. In this study, several electric machine designs have been explored and coupled with the propeller design to study the trade-off between the aerodynamic and acoustic performance of the propeller. Aerodynamic optimization is used as a baseline to minimize the energy consumption to find the aerodynamics optimum subject to constraints on the thrust levels during the mission. The propeller aerodynamic optimizer considers the electric machine efficiency map, which is a function of propeller torque and rotational speed, to find the optimum combination of propeller and electric machine designs. The objective function of the acoustic optimizations is to reduce the cumulative noise level over the entire mission. It is shown that a wider envelope of peak motor efficiency in the efficiency map provides acoustics and aerodynamic performance benefits. The trade-offs between reducing noise or increasing aerodynamic efficiency to reduce energy consumption are demonstrated.

The more-electric aircraft (MEA) concept has become a major trend due to its multiple advantages. Many functions which are conventionally driven by pneumatic, hydraulic and mechanical power systems are replaced by electrical ones onboard MEA. This results in increased electrical power demand for MEA. Due to power off-take limit from high-pressure (HP) spool of an engine, extra power needs to be extracted from the low-pressure (LP) spool. Besides, recent studies have revealed that transferring power between LP and HP shafts in certain flight missions, like taxiing and descending will not only decrease fuel consumption but also increase compressor surge margins. This paper introduces an enhanced power generation centre for the MEA applications. It extracts power from both HP and LP spools, with each shaft is driving one electrical generator. These generators supply electrical power to a common DC bus through active AC/DC converters. Using the droop-control concept, the power sharing between LP and HP shafts can be smoothly controlled. Control method when power transferred from LP spool to HP spool is also presented. This architecture is built and simulated in the Matlab/Simulink environment. Simulations results including performances of electrical machines, power converters and engine under different scenarios are presented in this paper.