Efficient power and thermal management system for high performance aircraft

Abstract

A system and method for improved system efficiency of an integrated power and control unit (IPCU) of an aircraft is disclosed. The system uses an open-loop cooling system and turbo machine power matching to provide wide operation range without over-sizing. In order to reduce the temperature of the air flow through the cooling heat exchanger, the cooling turbine need to expand further in the same time generating power but the power could be higher than the compressor could absorb so a generator that would convert the power and used in supplying the aircraft would result in more efficient system.

Claims

1. A system for providing electrical power and cooling for an aircraft having an engine, the system comprising: an integrated power and control unit (IPCU) starter/generator coupled to a shaft; a cooling turbine coupled to the shaft; a compressor coupled to the shaft between the IPCU starter/generator and the cooling turbine, said compressor having an input for receiving engine bleed air and an output for discharging compressed air while rotating the shaft; a power summing controller for coupling power from the IPCU starter/generator to a load of the aircraft; first and second buses for receiving power from the engine and coupling the power to one or more loads; a third bus for receiving power from the IPCU starter/generator and coupling the power to one or more loads; and first and second contactors, coupled to the power summing controller, for coupling the third bus to the first and second buses; a first integrated control unit (ICU) coupled to the IPCU starter/generator; a first current sensing unit (CSU) receiving an input from the ICU; and a IPCU contactor coupling the first CSU to the third bus; wherein the power summing controller further comprises a first electrical system distribution control unit (DCU) for controlling at least the IPCU contactor and the first and second contactors.

2. The system of claim 1, wherein the first and second contactors further comprise one or more bi-directional solid state, high power contactors.

3. The system of claim 1, further comprising: a low pressure (LP) generator coupled to the engine; a generator control unit (GCU) receiving an input from the LP generator; a second current sensing unit (CSU) receiving input from the GCU; and an LP contactor coupling the second CSU to the first bus; wherein the power summing controller further comprises a second electrical system distribution control unit (DCU) for controlling at least the LP contactor and the first contactor to couple the first bus to the third bus.

4. The system of claim 1, further comprising: a high pressure (HP) starter/generator coupled to the engine; a second integrated control unit (ICU) receiving an input from the HP generator and coupling it to a high pressure bus; a third current sensing unit (CSU) receiving input from the second ICU; and an HP contactor coupling the second CSU to the second bus; wherein the power summing controller further comprises a third electrical system distribution control unit (DCU) for controlling at least the HP contactor and the second contactor to couple the second bus to the third bus.

5. The system of claim 1, further comprising one or more energy storage devices operatively coupled to the third bus.

6. The system of claim 1, wherein the aircraft is operated as an open loop system wherein there is no feedback path from an output of the cooling turbine to an input of the compressor.

7. A method for providing electrical power and cooling for an aircraft having an engine, comprising the steps of: generating power for the aircraft using the engine and coupling the power to one or more loads using first and second buses; generating power for the aircraft using an integrated power and control unit (IPCU) starter/generator and coupling the power to a first integrated control unit (ICU); coupling the power from the ICU to first current sensing unit (CSU); coupling the first CSU to a third bus further coupled to one or more loads by using an IPCU contactor; coupling the third bus to the first and second buses using first and second contactors; and using a first electrical system distribution control unit (DCU) to control the IPCU contactor and the first and second contactors to sum the power from engine and the power from IPCU and apply it to a load of the aircraft.

8. The method of claim 7, where in the step of generating power for the aircraft using an engine further comprises the steps of: generating power using a low pressure (LP) generator and coupling it to the first bus; and generating power using a high pressure (HP) starter/generator and coupling it to the second bus.

9. The method of claim 8, wherein step of using the first electrical system DCU further comprises the steps of: receiving inputs indicating operating conditions from the IPCU, LP generator and the HP generator; and opening or closing at least one contactor in response to the inputs.

10. The method of claim 9, wherein the at least one contactors further comprise bi-directional solid state, high power contactors.

11. The method of claim 7, further comprising the step of: storing power generated by at least one of the engine and the IPCU in one or more energy storage devices.

Description

DESCRIPTION OF THE DRAWINGS

(1) Features of example implementations of the invention will become apparent from the description, the claims, and the accompanying drawings in which:

(2) FIG. 1 is a schematic block diagram of a prior art aircraft engine and integrated power and cooling unit (IPCU) in a closed loop configuration.

(3) FIG. 2 is a schematic block diagram of a prior art aircraft engine and integrated power and cooling unit (IPCU) in an open loop configuration.

(4) FIG. 3 is a schematic block diagram of an aircraft engine and integrated power and cooling unit (IPCU) according to the present invention.

(5) FIG. 4 is a schematic block diagram of a power summing apparatus according to the present invention.

DETAILED DESCRIPTION

(6) In one aspect, the invention provides an integrated power and cooling unit (IPCU) with improved peak power generation and cooling capability. A power summing technology is used to enable the cooling power generation and the control of the IPCU power balance.

(7) Turning to FIG. 3, an apparatus 300 according to the present invention is shown. Elements in common with FIGS. 1 and 2 have the same reference numerals. IPCU 100 of FIG. 3 is in an open loop configuration with engine 122, where the output of heat exchanger 140 is vented to ambient air by means of exhaust control valve 150. Cooling turbine 102, compressor 104, starter/generator 106 and power turbine 108 are all located on the same shaft 110, thus requiring power balancing between the elements. In other words, the power required by compressor 104, starter/generator 106, and the drag of the shaft bearing system must be equal to the power generated from the air expansion of cooling turbine 102 so that the proper operating speed is maintained.

(8) An additional input from engine 122 to IPCU 100 is provided through valve 149. This valve provides for a bleed air driven mode in the event that additional power is required to use engine bleed air boost. Valve 149 allows the use of engine bleed air from selector/regulator valves 144 and 146 to drive power turbine 108 so additional power is added to IPCU shaft 110 for cooling or power generation.

(9) In an embodiment according to the present invention, starter/generator 106 is used throughout the operation of the aircraft to support cooling generation and power regulation, especially during periods of peak cooling needs. Instead of limiting the discharging pressure of the cooling turbine 102 and the power generated from air expansion by limiting the air flow through heat exchanger 140 using regulator valve 150, excess power added to the system in the form of spinning shaft 110 by cooling turbine 102 is diverted by starter/generator 106 in generating mode through ICU 114 onto IPU bus 115. The power sum control 302 adds the extra power to LP bus 132 while power sum control 304 adds the extra power to HP bus 128 according to the bus loading conditions and operating modes and configuration of the entire electrical power system.

(10) FIG. 4 shows a block diagram of a power summing apparatus 400 according to the present invention. Elements in common with FIG. 3 have the same reference numerals. LP GEN 126 is connected to generator control unit (GCU) 134, which moderates the output power of the LP generator 126. GCU 134 is connected to current sensing unit (CSU) 402 which senses the current output from LP generator 126 and provides the sensed current to the point of regulation (POR) 406. POR 406 is placed in the LP generator 126 distribution system to measure the voltage of the system and provide it to GCU 134 for voltage control. From POR 406, energy originating from LP GEN 126 is transferred to BUS 132, then through power distribution system contactors 408 to loads 410, which can be any power or electrical needs in the aircraft. GCU 134 and power distribution system contactors 408 receive control signals from the electrical system distribution control unit (DCU) 404.

(11) DCU 404 monitors the electrical system operating modes, generator conditions, and POR 406 measurements to control the amount of energy generated from the LP generator 126. In a preferred embodiment, measurements from POR 406 are sent to GCU 134 and communicated with DCU 404. Typically, all controllers are on a control network and sharing data and information. LP generator 126 system DCU 404 also cross communicates with IPCU ST/Gen 106 system's DCU 414 and HP ST/Gen 124 system's DCU 426 to control the overall system operation. DCU 404 and DCU 414 also jointly control contactor 436 to determine whether of not electrical bus 132 and bus 115 should be connected to each other as explained in more detail below.

(12) Similarly, IPCU starter/generator 106 is connected to ICU 114, which moderates the output power of the IPCU starter/generator 106. ICU 114 is connected to CSU 412 which senses the current output from IPCU starter/generator 106 and provides the sensed current to the POR 416, which is placed in the IPCU starter/generator 106 distribution system to measure the voltage of the system. From POR 416, energy originating from IPCU starter/generator 106 is transferred to BUS 115, then through power distribution system contactors 418 to loads 420 and 422, which can be any power or electrical needs in the aircraft. ICU 114 and power distribution system contactors 418 receive control signals from DCU 414, which monitors the electrical system operating modes, generator conditions, and POR 416 measurements to control the amount of energy generated from the IPCU starter/generator 106.

(13) Likewise, HP starter/generator 124, ICU 130, CSU 424, POR 428, BUS 128, contactors 430, loads 432 and DCU 426 are interconnected similarly.

(14) A key feature of the present invention is found in cross-tie contactors 434 and 436. Unlike prior art relay type contactors, which provide operation on the order of 100 milliseconds, the inventive contactors 434 and 436 are, for example, electronic semiconductor switches, controlled by DCUs 404, 414 and 426. These switches operate on the order of microseconds, much faster than prior art relays. This allows near real time combination of power/energy from LP and IPCU by contactor 436, and IPCU 106 and HP 124 by contactor 434.

(15) Contactor 434 is a bi-directional solid state, high power controller which can be turned on and off in high speed, contrary to conventional mechanical relays. When contactor 434 is turned on, bus 128 and bus 115 are connected to each other and loads 432 and loads 420/422 are able to receive power from either HP generator 124 or IPCU ST/Gen 106. Even if conditions are such that contactor 434 is controlled to be in an on state, it may be opened to maintain system independence for system safety. This also limits the IPCU ST/Gen system transient due to peak loads operation from being propagated into the HP ST/Gen 124 system and thus, to avoid impacting the electrical power quality.

(16) Contactor 436 is a bi-directional solid state, high power controller which can be turned on and off at a high speed, contrary to conventional mechanical relays. When contactor 436 is turned on, bus 132 and bus 115 are connected to each other and loads 410 and loads 422 are able to receive power from either LP generator 126 or IPCU ST/Gen 106. Even if conditions are such that contactor 436 is controlled to be in an on state, it may be opened to maintain system independence for system safety. This also limits the IPCU ST/Gen system transient due to peak loads operation from being propagated into the LP ST/Gen 126 system and thus, to avoid impacting the electrical power quality.

(17) In an alternative embodiment, one or more energy storage devices (not shown) such as batteries or ultra-capacitors may be connected to bus 115 to store the energy generated from IPCU ST/gen 106 when additional cooling from cooling turbine 102 is generated. IPCU 100 can also be configured to receive engine 122 high pressure bleed air to drive the power turbine 108 to generate additional energy to charge the energy storage devices. In a further alternative embodiment, energy storage devices connected to bus 115 could also be charged by the LP generator 126 since contactor 436 allows the energy to flow from bus 132. During the time during which peak power loads are present, energy storage devices could be sized to provide the transient power needs and contactor 436 may be opened to limit the power transient propagated into the LP Gen 126 system. These two operating modes complement each other for efficient energy utilization.

(18) Numerous alternative implementations of the present invention exist. With advent of high power, light weight batteries, the IPCU generation requirements could be reduced but the cooling function would not be totally replaced. This configuration and principles could also be applied to power system requires more than two main generators and a backup generators for example multiple-engines aircraft.

(19) The steps or operations described herein are just for example. There may be many variations to these steps or operations without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified.

(20) Although example implementations of the invention have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.