Universal platform architecture for hybrid more electric aircraft

An aircraft power system includes a front-end power converter and a back-end power converter. The front-end power converter is configured to generate a first direct current (DC) supply voltage or a second DC supply voltage based on a voltage level of an alternating current (AC) supply voltage output from an AC voltage source. The backend power converter sub-system is configured to convert the first DC supply voltage or the second DC supply voltage into a backend supply voltage. An active power distribution system is configured to select different electrical paths between the front-end converter and the backend converter subsystem in response to detecting output of the first DC supply voltage and the second DC supply voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Indian Application No. 201811016787 filed May 3, 2018, which is incorporated herein by reference in its entirety.

BACKGROUND

Exemplary embodiments pertain generally to the art of aircraft systems, and more particularly, to more-electric aircraft systems.

Recent trends in the aircraft industry to pursue lighter and more efficient aircraft have led to the development of more-electric aircraft (MEA) and more-electric engine (MEE) systems. MEA systems are intended to replace one or more the pneumatic systems with electrically powered systems. Conventional MEA systems typically include individual electrical platforms to power the motor and direct current (DC) loads, respectively.

BRIEF DESCRIPTION

According to a non-limiting embodiment aircraft power system includes a front-end power converter and a back-end power converter. The front-end power converter is configured to generate a first direct current (DC) supply voltage or a second DC supply voltage based on a voltage level of an alternating current (AC) supply voltage output from an AC voltage source. The backend power converter sub-system is configured to convert the first DC supply voltage or the second DC supply voltage into a backend supply voltage. An active power distribution system is configured to select different electrical paths between the front-end converter and the backend converter subsystem in response to detecting output of the first DC supply voltage and the second DC supply voltage.

According to another non-limiting embodiment, a method of controlling an aircraft power system includes generating, via a front-end power converter, a first direct current (DC) supply voltage or a second DC supply voltage based on a voltage level of an alternating current (AC) supply voltage output from an AC voltage source, and converting, via a backend power converter sub-system, the first DC supply voltage or the second DC supply voltage into a backend supply voltage. The method further includes selecting, via an active power distribution system, different electrical paths between the front-end converter and the backend converter subsystem in response to detecting output of the first DC supply voltage and the second DC supply voltage.

DETAILED DESCRIPTION

Various embodiments described herein provide a hybrid MEA power system operable on an aircraft. The hybrid MEA power system includes a cascaded arrangement of a front-end converter, an active power distribution system, and a backend converter to provide a universal alternating current to direct current (AC-DC) or AC to AC (AC-AC) converter, which is configured to convert alternating current (AC) to direct current (DC) or AC to AC. The universal converter is capable of handling variable frequency and magnitude commonly found in aerospace applications while still providing shoot-through protections.

In one or more non-limiting embodiments, the universal converter converts a three-phase AC supply voltage (e.g., 230V AC or 115V AC) with three-phase variable frequency (e.g., about 360 Hz to about 800 Hz) to a DC supply voltage (e.g., +/−350V DC or +/−175V DC). The DC supply voltage can then be converted into a fixed DC voltage (e.g., 28V DC), and utilized to drive the aircraft battery charger or drive various aircraft DC loads. The converted fixed DC voltage can also be converted into a secondary backend AC supply voltage, which drives various motor applications such as flight control actuation, electronic braking, thrust reversal, or environmental motor control. Accordingly, a hybrid MEA power system is provided that can selectively generate power using an aircraft generator or an aircraft battery. Thus, in absence of AC power source, for example, the aircraft can still be powered using the battery power. The hybrid electrical architecture described herein also provides smart motor load sharing capability between two or more inverters working in synchronization, while protecting the motor or load from phase short circuits such as, for example, short-to-ground faults.

With reference now toFIG. 1, a hybrid aircraft power system100is illustrated according to a non-limiting embodiment. The hybrid aircraft power system100includes a front-end power converter102, an active power distribution system104, and a backend power converter sub-system106. The hybrid aircraft power system100is capable of operating in different power modes to distribute power between the front-end power converter102and a backend power converter sub-system106, while also sharing power among the individual components of the backend power converter sub-system106.

The front-end power converter102is connected to an AC voltage source108to receive an AC supply voltage. The AC voltage source108can selectively output a first three-phase voltage having a first voltage level of about 230V AC, for example, and a second three-phase voltage having a second voltage level of about 115V AC, for example. Accordingly, the front-end power converter102is configured to generate a first DC supply voltage (e.g., +/−350V DC or 700V DC across the entire bus) or a second DC supply voltage (e.g., +/−175V DC, or 350V across the entire bus) based on a voltage level of the AC supply voltage (e.g., 230V AC or 115 V AC) output from an AC voltage source108.

The output of the front-end converter102can be connected to a DC bus110including a positive rail capacitor112aand a negative rail capacitor112b. The positive terminal of capacitor112acan serve as a positive rail connection to the backend converter subsystem106, while the negative terminal of capacitor112bcan serve as a negative rail connection to the backend converter sub-system106. According to various embodiments, the series connection between the positive rail capacitor112aand negative rail capacitor112bmay protect the input to the backend converter sub-system106because the DC bus voltage does not exceed one half of the front-end rectifier high rail to low rail output voltage.

In one or more embodiments, the front-end power converter102converts the first AC supply voltage (e.g., 230 V AC) to a first DC supply voltage having a voltage level of about +/−350V DC, for example, and converts the second AC voltage (e.g., 115V AC) to a second DC supply voltage having a voltage level of about +/−175V DC, for example. In one or more embodiments, the front-end power converter102includes a multi-phase (e.g., three-phase) rectifier circuit113that rectifies the first three-phase voltage (e.g., 230 V AC) to generate the first DC supply voltage (+/−350V DC), and rectifies the second three-phase voltage (e.g., 115 V AC) to generate the second DC supply voltage (+/−175V DC). The multi-phase rectifier113includes a plurality of switching stages, each switching stage including a lower switch116a,116band116cconnected in series with an upper switch114a,114band114c, respectively. Each lower switch116a,116band116cis connected to a cathode of a lower diode118a,118band118c, respectively, while each upper switch114a,114band114cis connected to an anode of an upper diode120a,120b,120c, respectively. The lower diodes118a,118band118cinclude an anode connected to a lower capacitor112band the upper diodes120a,120b,120cinclude a cathode connected to the upper capacitor112a. In at least one embodiment, the multi-phase rectifier circuit113can be constructed, for example, as a Vienna rectifier.

The DC supply voltage applied to the DC bus110is delivered to the backend converter sub-system106via the active power distribution system104. In one or more embodiments, the backend converter sub-system106receives either the first DC supply voltage (+/−350V DC) or the second DC supply voltage (+/−175V DC) based on the operating mode of the hybrid MEA power system100, and is configured to convert the first DC supply voltage or the second DC supply voltage into a backend supply voltage. The backend supply voltage can include a fixed DC voltage (e.g., 28V DC) and/or another (e.g., third) AC supply voltage.

In at least one non-limiting embodiment, the backend converter sub-system106includes one or more bi-directional battery charger circuits122and one or more voltage converter circuits124. The bi-directional battery charger circuit122includes a first input in signal communication with the DC Bus110, a second input in signal communication with an output of the active power distribution system104, and an output in signal communication with a battery126installed on the aircraft. Accordingly, the bi-directional battery charger circuit122can charge the battery126based on the first DC supply voltage or the second DC supply voltage delivered to the DC bus110.

The voltage converter circuit124can include a DC-to-DC converter circuit and/or a DC-AC converter circuit. A voltage converter circuit124constructed as a DC-to-DC converter circuit can be utilized to convert the first DC supply voltage or the second DC supply voltage into a third DC supply voltage having a different voltage level (e.g., 28V DC) that drives a DC load (not shown) installed on the aircraft. The DC loads include, but are not limited to, cabin and cockpit lighting and display systems, and latching of solenoids used in electrohydraulic actuator systems. A voltage converter circuit124constructed as a DC-to-AC converter circuit can be utilized to convert the first DC supply voltage or the second DC supply voltage into a variable supply voltage of phase, frequency and amplitude as per the drives requirement of a motor128installed on the aircraft. In case of128as dc load, same124could be configured as Constant Voltage Current Source for driving the string of LED used to replace the halogen lights in recent MEA application.

The active power distribution system104includes a network of individual switches130and a power distribution controller132. Unlike conventional MEA power systems, the active power distribution system104included in the hybrid MEA power system100can invoke different power modes, which in turn establishes different electrical paths between the front-end converter102and the backend converter subsystem106. In one or more embodiments, the different power modes are selected based on the AC voltage supplied by the AC power source108and/or the DC supply voltage measured at the DC bus110. In this manner, the hybrid MEA power system100can selectively provide different power sources using an aircraft generator (e.g., the AC power source108) or the aircraft battery126.

Each switch130is operable in an open state and a closed state. In one or more embodiments, the switches130are constructed as field effect transistors (FETs). Accordingly the power distribution controller132can invoke the open state (i.e., deactivate the switch) and the closed state (e.g., activate the switch) by applying a control signal to the gate of the FET130. In one or more embodiments, the power distribution controller132can activate and deactivate various combinations of the switches130to establish different electrical paths between the front-end power converter102and the backend power converter sub-system106.

Turning toFIG. 2, the hybrid aircraft power system100is illustrated following the power distribution controller132initiating a first generator power mode in response to detecting input of the first AC supply voltage (e.g., 230V AC). In another embodiment, the power distribution controller132initiates the first generator power mode in response to detecting the first DC voltage level (+/−350V DC) at the DC bus110. In response to invoking the first generator power mode, the power distribution controller132activates a first combination of switches130while deactivating a first combination of switches131. Accordingly, a first electrical path is established between the front-end power converter102and the backend power converter sub-system106. The first electrical path defines a first electrical connection between the at least one bi-directional battery charger circuit122and at least one voltage converter circuit124. In at least one embodiment, the first electrical connection establishes a parallel connection between the at least one battery charger circuit122and the at least one voltage converter circuit124.

Turning toFIG. 3, the hybrid aircraft power system100is illustrated following the power distribution controller132initiating a second generator power mode in response to detecting input of the second AC supply voltage (e.g., 115V AC). In another embodiment, the power distribution controller132initiates the second generator power mode in response to detecting the second DC voltage level (+/−175V DC) at the DC bus110. In response to invoking the second generator power mode, the power distribution controller132activates a second combination of switches130while deactivating a second combination of switches131. Accordingly, a different second electrical path is established between the front-end power converter102and the backend power converter sub-system106.

The second electrical path defines a different second electrical connection between the at least one bi-directional battery charger circuit122and the at least one of a voltage converter circuit124. For instance, the second electrical connection can establish a first parallel connection between a plurality of battery charger circuits122and a second parallel connection between a plurality of voltage converter circuits124such that the first parallel connection (e.g., the parallel combination of battery charger circuits122) is connected in parallel with the second parallel connection (e.g., the parallel combination of voltage converter circuits124). In case of 115V input, the individual capacitors112aand112bshall charge to 175V. Therefore, the DC bus110realized 350V. The 350V is then fed to one or more individual bidirectional battery chargers122. The DC bus110also feeds the 350V to the voltage converter circuits124. Accordingly, the bidirectional battery chargers122and the voltage converters124are in parallel connection with respect to the DC bus110.

Referring toFIG. 4, the hybrid aircraft power system100is illustrated following the power distribution controller132initiating a battery power mode in response to detecting disconnection of the AC voltage source (e.g., either the 230V AC supply or the 115V AC supply). In another embodiment, the power distribution controller132can initiate the battery power mode in response to detecting that the voltage at the DC bus110is below a threshold value (e.g., below 5V DC). In another embodiment, the power distribution controller132can initiate the battery power mode in response to detecting an open circuit between the AC voltage source108and the active power distribution system104.

In response to invoking the battery power mode, the power distribution controller132activates a third combination of switches130while deactivating a third combination of switches131. Accordingly, a different third electrical path is established between the front-end power converter102and the backend power converter sub-system106. The third electrical path connects an output of the bi-directional battery charger circuit122to one or more voltage converter circuits124. Further, the third electrical path is configured to share the output of one or more bi-directional battery charger circuits between the voltage converter circuits124, e.g., one or more DC-to-DC converter circuits124and one or more DC-to-AC converter circuits124. The flow of battery power between the battery chargers124and the voltage converter circuits124is illustrated inFIG. 5.

In at least one non-limiting embodiment, the power distribution controller132can also initiate a hybrid power exchange mode, i.e., a hybrid power mode. When operating in the hybrid mode, the AC voltage source108can be either at first voltage level (e.g. 230V AC) or second voltage level (e.g. 115V AC). Turning toFIG. 6, for example, the hybrid mode is shown invoked while the AC voltage source108outputs the first voltage level (e.g., 230V AC). Accordingly, the power distribution controller132activates a combination of switches130and deactivates a combination of switches131as illustrated inFIG. 2, to establish electrical path that allows power flow between the bi-directional battery charger circuit122and front-end power converter102to voltage converter circuits124. Similarly,FIG. 7illustrates the hybrid mode invoked while the AC voltage source108outputs the second voltage level (e.g. 115V AC). Accordingly, the power distribution controller132activates a combination of switches130and deactivates a combination of switches131as illustrated inFIG. 3, to establish electrical path that allows power flow between the bi-directional battery charger circuit122and front-end power converter102to voltage converter circuits124. In either scenario, the power required by load128is optimally shared between AC voltage source108and battery126by maximizing power utilization from battery126according to its charge accumulation capacity.

In at least one embodiment, the total power necessary to drive one or more targeted loads is determined. For example, the controller132can determine a power differential (ΔP) between the power output from the battery126and the power required to drive the load(s). The remaining power necessary to meet the total load power (i.e., the total power necessary to drive the target load) can then be supplied using the AC source voltage108. Accordingly, the targeted load is driven using both the battery power and the AC source voltage.

Turning now toFIGS. 8A-8B, a flow diagram illustrates a method of controlling a MEA hybrid power system according to a non-limiting embodiment. The method begins at operation600and at operation602determines whether an AC source voltage is available. When the AC source voltage is unavailable, the method invokes the battery power mode at operation604, and determines whether one or more motors installed on the aircraft system require power at operation606. When no motors require power, the method proceeds to operation608, and determines whether one or more DC loads require power. When no DC loads require power, the method ends at operation610. When, however, one or more DC loads require power, the method supplies the battery voltage (e.g., 28V DC) to the DC load(s), and the method ends at operation610.

When one or more motors require power at operation606, the battery voltage is converted to an AC supply voltage at operation614. At operation616, the AC supply voltage is supplied to the motor(s), and the method ends at operation610.

Turning back to operation602, the method determines that an AC source voltage is available, proceeds to operation617to determine whether the hybrid mode is invoked. When the hybrid mode is not invoked, the method proceeds to operation618to determine the power level of the AC source voltage. When the AC source voltage is determined to have a first AC voltage level (e.g., about 230V AC), the method proceeds to operation620and converts the first AC voltage level into a first DC voltage level (e.g., +/−350V DC). At operation622, a first generator mode is invoked and the battery charger(s) and backend voltage converter(s) installed on the aircraft are connected in parallel with one another. At operation624, the first DC voltage (e.g., +/−350V DC) is delivered to the battery charger(s) and backend voltage converter(s), and the method ends at operation610.

Turning back to operation618, when the AC source voltage is determined not to have the first AC voltage level, but has a second AC voltage level (e.g., about 115V AC) at operation626, the method proceeds to operation628and converts the second AC voltage level (e.g., about 115V AC) to a second DC voltage level (e.g. +/−175V DC). Accordingly, a second generator mode is invoked such that a plurality of battery chargers are connected in parallel at operation630, a plurality of backend voltage converters are connected in parallel at operation632, and the parallel combination of battery charges and the parallel combination of backend voltage converters are connected in parallel at operation634. The second DC voltage level is delivered to the battery chargers and the backend converters at operation636, and the method ends at operation610. In this manner, the parallel combination of bidirectional battery charger to the voltage converter124allows for establishing several parallel combinations of bidirectional battery chargers122, which can fulfill the power demand of several voltage converter124, despite the number of voltage converters124being greater than the number of bidirectional battery chargers122, or vice versa.

Referring back to operation617, when the hybrid mode is invoked the method proceeds to operation638(seeFIG. 8B) and discharges power from the battery. At operation640, the total power necessary to drive one or more targeted loads is determined. At operation642, a power differential (ΔP) between the output battery power and the necessary load power is determined At operation644, the remaining power necessary to meet the total load power (i.e., the total power necessary to drive the target load) is output from the AC source voltage. At operation646, the targeted load is driven using both the battery power and the AC source voltage, and the method ends at operation610.

As described herein, a hybrid MEA power system is provided, which includes a universal converter that converts a three-phase AC supply voltage (e.g., 230V AC or 115V AC) with three-phase variable frequency (e.g., about 360 Hz to about 800 Hz) to a DC supply voltage (e.g., +/−350V DC or +/−175V DC). The DC supply voltage can then be converted into a fixed DC voltage (e.g., 28V DC), and utilized to drive the aircraft battery charger or drive various aircraft DC loads. The converted fixed DC voltage can also be converted into a secondary backend AC supply voltage, which drives various motor applications such as flight control actuation, electronic braking, thrust reversal, or environmental motor control. Accordingly, a hybrid power system for a MEA system is provided that can selectively generate power using an aircraft generator or an aircraft battery. Thus, in absence of AC power, for example, the aircraft can still be powered using the battery power.