Jon Zumberge

Energy Management of an Aircraft Electrical System

Advancements in electrical, mechanical, and structural design onboard modern more electric aircraft have added significant stress to the electrical systems. An electrical system level analysis tool has been created in MATLAB/Simulink to facilitate rapid system analysis and optimization to meet the growing demands of modern aircraft. A segment level model of the electrical system including the generator, electrical accumulator unit, electrical distribution unit and electromechanical actuators has been developed. Included in the model are mission level models of an engine and aircraft to provide relevant boundary conditions. It is anticipated that the tracking of the electrical distribution through numerical integration of these various subsystems will lead to more accurate predictions of the bus power quality. In this paper the tool is used to evaluate two architectures. The first architecture makes use of an electromechanical accumulator unit to handle the regenerative energy created by the electromechanical actuators. In the second architecture power resistors in the actuator electronic units are used for dissipation of regenerative energy. MIL-STD 704F and energy used was utilized in evaluating capability of the two systems. The electrical accumulator unit showed some degradation in electrical bus stability; however it did meet the requirements of MIL-STD 704F and showed reduced energy usage for the flight maneuver tested. I. Introduction he widespread use of more electrical equipment on an aircraft is driving the need to evaluate electrical stability of the system. Military standard-704 defines requirements for the behavior of such systems. However, evaluation of these systems typically has been done with hardware and this late evaluation can lead to increased costs. However, if such evaluation can take place earlier in the development process before pre-production hardware is built considerable cost savings can be achieved. A tool is being developed that can better quantify electrical stability through simulation of integrated electrical systems. This modeling tool makes use of models developed with bandwidth up to one hundred kilohertz. These models are defined in the Integrated Vehicle and Energy Technology (INVENT) Modeling Requirements and Implementation Plan (MRIP) as segment level models [2]. The MRIP document further defines the interfaces between the various electrical systems. This document is not limited to electrical, but includes the entire aircraft systems (thermal, mechanical, aerodynamic, etc.). In addition to the increase in power usage, there is an additional issue with regenerative power of the actuators. With the move to the more electric aircraft, the actuators have changed from conventional hydraulic actuators to electro-hydrostatic actuators (EHA) and electro-mechanical actuators (EMA). Use of these actuators forces a need to deal with large regenerative power to the bus. Most applications with actuators are using resistors to “burn off” energy regenerated by the actuator and prevent the energy from returning to the bus. However, the regenerative energy dissipated in the actuators is a concern for thermal dissipation and additional energy required to cool the actuators. Recently in the research field, electrical accumulator units have been identified as a potential technology for solving this problem [3]. An electrical accumulator unit is a battery / capacitance like technology that can absorb

On regenerative power management in more electric aircraft (MEA) power system

This paper discusses three power system topologies that are capable of handling regenerative power in EMA loads for more electric aircraft (MEA). A simple power system including a synchronous generator, an electromechanical actuator (EMA) and an electric accumulator unit (EAU) is builtto show the effectiveness of regenerative power management using EAU.

Design and modeling of a five-phase aircraft synchronous generator with high power density

This paper presents a methodology for the design and modeling of a five-phase aircraft synchronous generator with high-power density. A new method was recently proposed for a more accurate model of the air-gap of a salient pole rotor through expanding the inverse of an effective air-gap function for three-phase synchronous generators. This approach is adapted to the five-phase case here, with some modifications to the derivations. Five-phase decoupling direct-quadrature theory is reviewed and presented as the basis for linear modeling of the five-phase synchronous machine. Following the procedure for a three-phase design with five-phase considerations, a 200 kVA high power density synchronous generator with 12 krpm rotational velocity is obtained. Finally, the design is verified using finite element method software.

Modeling and control scheme design of a solenoid-actuated fuel injection system

This paper demonstrates the viability of frequency modulation of discrete voltage pulses via feedback loops as a means of control for an electronically actuated fuel injection system. Specifically, this study targets the effectiveness of such control with regards to the Hydraulically actuated Electronically controlled Unit Injector (HEUI). A more accurate model for electromechanical actuator (EMA) using solenoid has been implemented together with models of other subsystems. Significant improvements have been made to the existing MATLAB/Simulink modeling approach in order to implement a higher degree of system control.