Figure 2 - uploaded by Robert Alan McDonald
Content may be subject to copyright.
Digitized data from published motor map. The grey circles represent all digitized points. The black squares represent the subset used to fit the motor map.
Source publication
Electric motors have achieved very high efficiency and reliability; and in some cases, very high specific power. As the energy storage capabilities of batteries and fuel cells advance, these technologies are increasingly being considered for aircraft primary propulsion. In order to design electric aircraft, aircraft designers must be able to unders...
Contexts in source publication
Context 1
... this example, the efficiency contours from Figure 1 were digitized and the resulting data was fit to a positive polynomial power loss model. The complete set of digitized points are depicted in Figure 2 as grey circles and black squares. Using all of this data biased the surface fit to the low speed and low torque regions of the operating envelope, which resulted in relatively poor performance capturing the rest of the envelope including the efficiency peak. ...
Context 2
... all of this data biased the surface fit to the low speed and low torque regions of the operating envelope, which resulted in relatively poor performance capturing the rest of the envelope including the efficiency peak. Instead, only a subset of the data was used for the fit; the results presented in this paper were generated by fitting the surface to only the black squares in Figure 2. ...
Similar publications
As the energy storage capabilities of batteries and fuel cells advance, these technologies are increasingly being considered for aircraft primary propulsion. In addition to other fundamental differences from conventional systems, these concepts may have constant or even increasing mass throughout the mission. In this paper, the implications of cons...
Citations
... Because the level of modeling for these electrical characteristics governs the analysis accuracy and design feasibility, more sophisticated modeling of an EPS is essential in the conceptual design of eVTOL aircraft. However, previous studies [12][13][14][15][16][17][18][19][20][21][22][23][24] have shown a limited ability to faithfully reflect the electrical characteristics of EPSs in the analysis and design of eVTOL aircraft. ...
... McDonald [19,20] proposed a positive polynomial loss model that can capture the motor efficiency without requiring intricate electric machine modeling, provided that information on the motor efficiency map is available. Because it can be easily applied in the initial design stage, this polynomial loss model has been used in conceptual design studies of various eVTOL aircraft [12,21,22]. ...
This paper proposes novel enhancements to the electric propulsion system analysis method for electric vertical takeoff and landing (eVTOL) aircraft conceptual design by considering the electrical characteristics of each electrical device in a more accurate manner. To this end, three modules for motor, inverter, and battery analysis are constructed using equivalent circuits and semi-empirical models. First, the motor analysis module is developed using equivalent circuit analysis with the operation control strategy for a permanent-magnet synchronous motor. Second, the inverter analysis module is built using average loss models for the switching and conduction losses. Third, the battery analysis module is improved using the near-linear discharge model to consider the voltage drop during operation. Moreover, additional modules, such as those for calculating the battery stack in series and parallel, as well as regression models for the motor and inverter performance parameters and consideration of the drive system type (direct or indirect, including a reduction gear), are implemented. A comparative study is presented from an analysis and design perspective while changing the drive system type (direct or indirect) and gear ratio, which highlights the importance of modeling electrical characteristics during eVTOL aircraft conceptual design.
... On the other hand, parameterization of the electric propulsion is a relatively new area of research and one of the main topics in the development of eVTOLs. One of the first electric motor performance modeling studies was introduced by McDonald [19] in 2013 for aircraft conceptual design studies. Duffy et. ...
Most of the introduced eVTOL models in the UAM market utilize electrically driven rotors with fixed pitch blades, controlled by their rotational speed. This design approach brings new features and challenges that need to be considered during the conceptual design stage, taking new aspects into account, among them the rotor dynamic response. This paper presents an initial parameterization of the rpm-controlled rotors along with the electric motor, based on the conducted literature research. Several isolated rotor variants are modeled and analyzed in terms of performance, and the dynamic response of the rotor rotational speed. The relations between aerodynamics and inertia are discussed, and their effects on the rotor dynamic response are elaborated on.
... where the k parameters are loss coefficients as defined by McDonald [29], ω stands for angular speed, and Q represents torque. For the loss coefficients, data from both the electric motor and Zamboni et al. [30] were used. ...
... A motor map is constituted by the motor operating envelope and its part-power efficiency behavior, and according to this model, for the operating range of the electric motor to be fully determined, there are three further coefficients, k P , k Q , and k w , that need to be defined. Following McDonald's work [29], these can be established as a function of the rated (marked by the subscript rated) and ideal (denoted byˆ) characteristics of the electric motor: ...
Life without mobility is inconceivable. To enable this connectivity, one must find a way to progress towards a more sustainable transportation. In the aviation industry, a comprehensive understanding of greening technologies such as electrification of the propulsion system for commercial aircraft is required. A hybrid-electric propulsion concept applied to a regional aircraft is studied in the context of the FutPrInt50 project. To this end, the hybrid-electric propulsive system components are modeled, validated, and evaluated using computational and experimental data presented in the literature. The components are then assembled to construct the three powertrains for the hybrid-electric propulsion systems (Series, Parallel and Turboelectric) and parametric studies are carried out to study the influence of various battery parameters and hybridization factor. The performance results for a simple mission profile are generated. Together with a thermal management system, multi-objective optimization studies for the different architectures are then performed, with the power hybridization factor as the design variable and minimization of total mass and emissions as objective functions.
... The studies presented in [1][2][3][4] describe matching using three criteria, using propeller performance curves, an electric motor efficiency map, and flight conditions. The propeller model was used to obtain various parameters such as Coefficient of Thrust ( ), Advance Ratio ( ), Coefficient of Power ( ) Torque, and RPM for these studies. ...
... Least square method to fit these parametric coefficients C are proposed in [29]. In [30], a more analytical and intuitive way of obtaining these parameters based on the parasitic power and peak motor efficiency is proposed and they are illustrated in (14)- (17). ...
... ,min ≤ ≤ ,max (28) ,max ≤ ≤ ,min (29) , ...
Energy storage system (ESS) integrated all-electric ship (AES) is gaining popularity as it renders higher efficiency and emission reduction. Being an isolated system, generation and storage capabilities are limited, and hence network losses, mechanical and electrical load estimation must be modeled accurately to establish a reliable operation strategy. Thus, the presented work proposes a modeling and operation strategy based on the propulsion architecture, mission profile, operation modes, and thermal performance of ESS. The following aspects are incorporated to improve the accuracy. (1) Electrical load demand, and loss modeling at the generation and load side; (2) energy management system (EMS) for optimal energy dispatch; (3) and experiment-based ESS electrical characterization and cooling designs for the thermal management system. Firstly, mathematical models of electrical components and mechanical propulsion units are used to establish the net electrical load demand from the propulsion and auxiliary units. The parameters obtained from load models are used in EMS energy dispatch to minimize the fuel and thermal-performance-dependent ESS operation costs. Finally, generation side losses are included in the final dispatch to meet the net electrical load demand of the vessel. Based on electrical parameters from test setup and different cooling designs, a battery management system is modeled to estimate the ESS pouch’s temperature profile that is used as an operational constraint of EMS to discourage ESS from operating at high temperatures. Simulation results indicate the impact of AES propulsion architecture and ESS thermal performance on its operation. The results suggest the strong influences of mission profile and operation modes in designing a realistic operation schedule for the actual implementation.
... To represent the motor dynamics of the lift rotor motors, the loss buildup approach of Larminie and Lowry [13] was used. It was shown by McDonald [14] that this type of approach can capture efficiency islands in the torque-speed envelope that are common in many motor types. The power balance on the motor can be represented as ...
The novel Urban Air Mobility and On-Demand Mobility aircraft being actively developed today have configurations that differ significantly from conventional fixed- and rotary-wing air-craft, as well as multi-rotor/distributed propulsion systems that are electric or hybrid-electric in nature. It is likely that the first generation designs will be highly-augmented vehicles operated by pilots who have less training than commercial airline pilots. As a result, there is a strong need for research on (i) stability and control characteristics of these configurations; (ii) development of flight control systems aimed at Simplified Vehicle Operations; and (iii) interactions of pilots with the flight control and other vehicle systems. This paper discusses the design of a Total Energy Control System and Total Heading Control System for a lift-plus-cruise Urban Air Mobility vehicle concept. Both inner and outer loop control design are discussed for the vehicle’s entire flight regime, with a focus on achieving seamless transition between vertical and forward flight modes without adding to pilot workload. Some aspects of the flight control system and its characteristics are demonstrated through some piloted simulations performed using one of the Vehicle Systems, Dynamics, and Design Laboratory’s flight simulators.
... [13] • Existing components models developed for electric aircraft, e.g. [17], [18] Evolving from the current body of knowledge, the original contribution of the project for closing the research gap arises from the objectives: ...
... This has been performed for single components (e.g. electric motors, by McDonald [17]), but there is a lack of knowledge when complete hybrid-electric propulsion systems are considered. ...
... The efficiency model is based on the work of McDonald [17], who suggests that the main power losses of an EM correlate with ω and Q. His model, in turn, is based on the work of Larminie and ...
Dr Finger researched design methodologies for aircraft that use hybrid-electric propulsion. He developed a new method to assess novel aircraft concepts. The findings indicate that hybrid-electric propulsion is not suited for any new aircraft, but for specific missions and applications, this technology can offer significant savings of energy and cost.
... The available efficiency map was processed, and the contour lines digitised, to which a polynomial loss model was fitted based on the work of McDonald [89]. Using the polynomial loss model, an accurate performance representation of the electric motor capabilities is achieved. ...
Stakeholders envision the introduction of electric and hybrid-electric aircraft into operation by 2035. First developments of such aircraft have demonstrated that the existing technologies do not allow realization of hybrid-electric aircraft matching the performance of traditional aircraft with the same load factors. The major challenge of future hybrid-electric aircraft development is the considerable improvement of the energetic efficiencies. This paper evaluates the (i) problems and barriers (ii) emerging and required future technologies of effective hybrid-electric propulsion systems and (iii) adaptation of the aircraft conceptual design process for the development of hybrid-electric aircraft. The developed methodology is applied to the conceptual design of a small aircraft with hybrid-electric propulsion system. The results demonstrate that the adapted conceptual design methods with (i) constrains on mass fraction adapted to new technologies and solutions, (ii) constraints defined for energy fractions for flight mission legs, (iii) considering radically new elements and technologies in aircraft design and (iv) developing unconventional aircraft, aircraft operations may allow the development of small hybrid-electric aircraft with acceptable performance.
... Let η i ∈ (0, 1] denote the efficiency of the i th actuator ‖ covering both electical and mechanical losses [10]. Given the aerodynamic propeller torque τ i as defined in Eq. (1), the electric power consumption P i ≥ 0 follows as * * ...
... Hence an efficiency map is created. The efficiency model is based on [21], which suggests that the main power losses of an electric motor correlate with the angular frequency and the torque . Consequently each coefficient to 3 of the polynomial approach in Eq. 4.2 represent one of the main losses for each electric machine. ...
In this paper, an approach to propulsion system modelling for hybrid-electric general aviation aircraft is presented. Because the focus is on general aviation aircraft, only combinations of electric motors and reciprocating combustion engines are explored. Gas turbine hybrids will not be considered. The level of the component's models is appropriate for the conceptual design stage. They are simple and adaptable, so that a wide range of designs with morphologically different propulsive system architectures can be quickly compared. Modelling strategies for both mass and efficiency of each part of the propulsion system (engine, motor, battery and propeller) will be presented.
