New technologies in electrical drives and power distribution in future aircraft
and Sureshkumar *
* professor in EEE department
ind sathak Mohamed College
Kilakkarai
E-mail: @ Sify uskrk. com
Abstract:
It is expected that in future aircraft, all powers except the power, distribution and handled electronically. In other words, the power required to drive aircraft subsystems used currently powered by hydraulic, pneumatic or mechanical, including utility and operation of flight controls, environmental control, lubrication and fuel pumps, and many other utility functions. These concepts are embraced by the so-called “More Electric Aircraft (MEA) initiative known. The MEA emphasizes the use of hydraulic power, pneumatic and mechanical optimization of aircraft performance in front and lifecycle costs. It would be the need for gears and transmissions, since the transmission is removed by electric rather than mechanical, which reduces the weight of the aircraft and fuel consumption increases. Detailed analysis
Interaction between an electro mechanical actuator (EMA) of bus power distribution in a transport plane of new generation by the bus controller is presented. Development of power systems-by-wire for reliable operation of the air and space applications has recently sought to eliminate the hydraulic systems of aircraft. Plan
Engineers have combined electrohydrostatic actuators (EHA), electrical power and water, so that the test
evolutionary “More Electric Aircraft” idea. Efforts are being made to replace
hydraulic systems with electrical systems, new technology will called “All Electric Aircraft”.
Introduction:
flight control systems (FCS) will be divided as follows:
FCS mechanical
The FCS is the basic mechanical design. They were in the plane at the beginning and now in small aircraft where aerodynamic forces are not excessive. The FCS uses a collection of mechanical parts such as rods, cables, pulleys and sometimes chains, the forces of the cockpit controls to pass the bar.
The complexity and weight of a mechanical CSF significantly increases the size and capabilities of the aircraft. Hydraulic overcomes these limitations
A hydraulic FCS has two parts:
The mechanical circuit links in the cockpit with hydraulic systems. As the FCS mechanical, it is made of rods, ropes, pulleys, chains and sometimes. The hydraulic system provides hydraulic pumps, pipes, valves and actuators. The hydraulic pressure of the pump in the hydraulic circuit powers the actuators generated. The actuators convert hydraulic pressure in the rudder movements. The servo motion control drives. The above two systems has a major drawback in that it contains a strong mechanical circuit, which increases the weight of the system. has been developed to overcome this drawback, a new technology, “More electric technology in aircraft. The plane in which this technique was used” More Electric Aircraft (MEA) was.
The description of AEM systems, flight control actuation can include technologies such as two main areas: Fly-by-wire (FBW) and power-by-wire (PBW) are. FBW technology includes the design, development and implementation of the electronic flight control. Electronic control provides flight control and control functionality implemented in actuator is centralized or distributed architectures. Distributed Control to reduce the load on the central processing of the flight control computer, and provide more flexibility in developing the system architecture. Another advantage is the reduction in weight achieved by climbing harness size and component quantity. In recent years, technological advances in the field of FBW was centered, to the extent that the FBW control systems are now the norm in commercial and military aircraft today. Power-by-wire (PBW) control actuation is the next big breakthrough in the plane. Like fly by-wire system of flight control eliminates the need for mechanical interfaces, actuators eliminate power-by-wire, the need for a hydraulic. controlling power comes directly from the device’s electrical circuit. This has several advantages. Central water systems are complex and difficult to maintain. The removal of these systems significantly reduce the amount of support equipment and personnel would be needed to maintain and operate the current air and space vehicles. In addition, PBW actuators have the potential to be more efficient than their hydraulic counterparts. A central hydraulic system must generate and maintain a high hydraulic pressure (3000-6000 psi) at any time, regardless of the application. PBW actuators used only when the electric energy needs. Finally, control systems PBW be much more tolerant than ever on a hydroelectric power. Once a hydraulic line is compromised, it usually leads to loss of all the hydraulic system. Consequently, several hydraulic circuits are required to obtain a degree of redundancy. With PBW system can not be disabled, an actor simply to isolate the problem to a single interface.
Reader Types PBW
There are different types of PBW actuators, including actuators electrohydrostatic (EHA) and electro-mechanical actuators (EMA). EHA use a reversible, electrically driven pump, pump motor directly to a separate hydraulic fluid piston. This causes the ram in the same way as a standard hydraulic jack (Figure 1 (a)). EMA does not have an internal hydraulic fluid, rather than going directly to electric motors of the RAM by a mechanical gearbox (Figure 1 (b)). Compared to an EHA, the EMA has certain advantages. It is lighter, smaller and less complex than equivalent EHA because of the lack of an internal hydraulic system. Since there is no hydraulic fluid in the load path, EMA tends to be more rigid than the equivalent EHA. The EMA tends to be more effective because there are no kayak or inefficiency of the pump. Finally, there is no potential leaks with EMA, it is preferable to long-term storage or space applications.
electromechanical actuators (EMA)
EMA uses a manual gearbox torque of an electric motor, a rudder in the air. This is achieved through a gear rotation, and function required for the method of operation, form a rotary to linear conversion, as a ball screw are. Electric motors, which are a source of DC is generally used, although the addition of a diode rectifier stage also allows them to operate from an AC supply. Engine speed, direction and torque to be translated directly, speed, direction and intensity in the drive. Figure 1 shows an EMA is being developed by TRW for an application of high power flight controls. In its basic form is EMA susceptible to failure at one point some which may lead to a mechanical blockage, and thus provides complications for the certification of flight on some surfaces. Additional devices can be used to have risen up against the reduction in case of failure, but the complexity, cost and weight. For these reasons, the EMA database applications are not suitable for primary flight control. However welcome the spoiler actuation systems and subsystems technology could EMA.
EMA-layout system
EMA Broadband flight control at high power
Basic architecture of power system
The power distribution system proposed is built around a 270V DC bus distribution. The basic architecture typical power system for a new-generation aircraft is in Figure 1 we see that are the key elements that control the power of the power converter bi-directional (BDC). A control bus provides an interface between the starter-generator and the distribution bus. Most loads, including the actuators are controlled bidirectional power converter, control and power status of the DC bus.
With the proliferation of power converters and two-way players at peak power, it is important to develop methods to analyze the interaction between different subsystems. Because of the complexity of basic foodstuffs and many sub-systems, a sample energy distribution, which captures the essential features of the base system, but is not that complicated, is introduced. The electrical system of the sample is represented as a composite of a source and under-load.
Sampling System Power Distribution
The power of sample 2 in Figure subsystem subsystem consists of a source is an ideal voltage source in three phases, an increase of three-phase rectifier with 270V regulated by the DC bus is required. The last subsystem of subsystem 2 shows an electromechanical actuator is used to define secondary flight control surfaces control the aircraft. Other expenses on the DC bus of a power source or a simple resistance.
The EMA model in Figure 5 shows that includes a DC motor with constant field, a ball screw transmission between the engine and rudder, and a model of the surface dynamics. The motor voltage is controlled by a PWM buck converter with bi-directional input filter. The EMA is a multi-loop controllers motor current, motor speed includes controlled, and feedback loops ball screw position. All other loads on the bus are modeled by a resistor or a current source.
electro hydrostatic actuators (EHA)
electrohydrostatic actuators (EHA)
Grand EHA
EHA control schematic
Advantages of electrically controlled actuators:
The potential benefits of the level of electric drive system are well known.
The electrical activity can provide:
The main advantage is the reduction of operating costs of aircraft, such as reduced fuel costs (as a consequence of reduced weight), and low maintenance costs (faster turnaround). However, before these benefits can be achieved, additional work is needed to improve technology and introduce the appropriate application of technology platforms in operation.
In addition, the industry of aircraft maintenance to align their infrastructure so they can enjoy the benefits of electric technologies.
Some additional advantages of both EMA and EHA actuators are:
EHA versus EMA?
An alternative to electromechanical actuators are EHA (EMAS), in which the motor torque and mechanical Improved ECU with a set of wheels, screws or other means of mechanical transmission can be considered as an alternative. In fact, as far as the complexity, weight, reliability and maintenance costs are concerned, EMAS are potentially more attractive than EHA, at least for low power applications. In particular, every water technology issues are clearly relevant configuration EHA eliminated. But in the three areas EMAS EHA even better:
? The likelihood of fault EMA is used in applications of primary flight control are difficult to predict and demonstrate the experience of existing service. Jamming probability of EHA can be evaluated directly from the experience of enslavement today, and listed as “extremely unlikely” if they bypassed correctly. In contrast, the probability of jamming of mechanical systems with hundreds of gears and screw mechanisms questionable experience and current applications in secondary flight controls can not directly transferable to primary flight controls due to very different work cycles, especially
The deterioration of mechanical components may transfer to the paddle “result of free-play or other nonlinearities, which can not generate acceptable limit cycles
? The introduction of an EHA is parallel to slavery in the regular basic architecture described above, more electric light of EMA. EHA is easily reversible standby mode, it can be identical damping devices, which currently fly to integrate the use of protection, and they can with many components in common with the adjacent servo, such as pistons, cylinders, displacement transducer or constructed to be associated with an accumulator. In a clear move to disseminate technical and financial risks that Airbus has called the talents of several companies in the development, production and delivery of several actuators on the aircraft giant. More specifically, the fins and rudders and elevator EHA A380 purchased EBHAs Goodrich, Messier-Bugatti is associated feed pumps EHA. Meanwhile, the spoiler EBHAs Liebherr, which provides its own pumps. Phil Hudson, Goodrich VP Engineering for operating systems, said: “The concept of electronic EHA can also be used with more features than just motor control is. It can serve as a drive controller chip in its own right and are part of a distributed control system or control of a group of several actuators. Another advantage is that the technology of the distributed intelligence of the actuators in a local control system and can significantly reduce the weight harness and improve the detection and isolation. ”
On maintenance are also significant benefits. EHA actuators Power-by-wire are replaceable hard disk with only mechanical and electrical connections to the planes, thus eliminating the need for a refill or purge systems of hydraulic fluids, if necessary with the central hydraulic. Since electric actuators-by-wire are autonomous and removed from the distance to the surface, damaging the surface is exposed to considerably reduced. In addition, the actuators power-by-wire can tough position, which means that the actuators move the flow and pressure required, the reader provides the means to be such a desired
Position. Classics central hydraulic systems are designed to generate a continuous pressure. The flow is measured on each drive, which can lead to high consumption and generate unwanted heat. William Schley, director of R & D, Parker Aerospace Controls Systems Division reported that EHA consume only upon request. Specifically, they consume energy in proportion to the current supplied to the load. In contrast, consumes energy with conventional hydraulic servo drive EVSV in speed ratio, the distribution of the burden as necessary, with the rest of the energy dissipated by the pressure drop (heat) on the main control valve. Although hydraulic actuators are more efficient, they are charged, most consumers in general when a flight is low. “Another important benefit of electric drives is the ability to survive. Ballistic or explosive damage to an electricity distribution or actuator is not usually a loss of function of the entire channel, especially if the damage is peripheral . In a hydraulic system according to performance, because even a small leak in a significant loss of function and / or fire. Although some electric motors contain
hydraulic fluid, the system as a whole is generally more viable. For now, the failure of the extended functions of management of EHA and its variants are planned. EHA combines the best of conventional hydraulic and electric drives for hybrid design approach is more tolerant than most current EMA. In addition, EHA mechanically simple and the immune system machinery congestion. The storage capacity of typical long-term EHA is 10 years and over.
— Aircraft new generation all-electric:
The all-electric “aircraft is a concept that originated in the 1970s and has generated a lot of research. An all-electric engine that could replace the current aero gas turbines would run all electrical devices, nestled on a distribution network of motor / generator in the motor windings. Expand the function of the motor / generators, including service as an active magnetic bearing would facilitate removal of the oil. The concept offers all-electric therefore considerable scope for manufacturers of engines and aircraft reconfiguration and operational improvement, studies showing the benefits of the total weight, greater reliability, easier maintenance, operating costs (including consumption of reduced fuel) and increased security.
Conclusion
replaced with the assumption of a single hydraulic power an electric motor, it is possible, the theory of relativity and the magnitude of change in the migration to “All-Electric Aircraft” is necessary. On a small civilian aircraft, usually at least five electric motors would be required to provide a trace of electrical controls for the surfaces of primary flight controls. With hydraulic systems have been converted to electricity, more than 20 electric actuators would be needed for complete control of all primary and secondary flight control surfaces. The resulting increase in electricity demand has significant implications for the power generation and distribution. Thus, a substantial amount of work still needed to track the spread of electric drives in many aircraft and address resulting from startup, steady supply of state and peak loads of aircraft electrical power.
It is clear that the conversion to electric drive systems for civil and military markets. As described above, the replacement of a single hydraulic system is an important step by an electric motor replaced in the transition to all-electric technology. It is obvious that the requirements for generators of the plane and the distribution architectures is much more to meet the needs of this migration. A company called TRW has already introduced products to the current requirements of justice and PBW developed programs to ensure they meet the future needs of the all-electric airplane. Finally, it is expected that once operational, power transmission and electrical system architectures for money and service reliability of the cell will be improved, for which they are installed. These improvements will undoubtedly encourage the adoption of a higher level of electrical system aboard future aircraft.
References:
D. Tesar, UT Austin, Robotics Research Group April 1, 2006