Patent Description:
Hybrid electric powerplants combine combustion and electric propulsion technologies. In an electric propulsion system for an aircraft, electrical energy is converted to mechanical energy by an electric motor to drive a rotor, such as a prolusion fan or a propeller. There are environmental and cost benefits to having at least a portion of the power for an aircraft propulsion system come from electric motors.

While existing power management systems for hybrid electric powerplants are suitable for their purposes, improvements are desired.

<CIT> discloses a method for limiting setpoint torques during engine control.

<CIT> discloses a vehicle torque monitoring system.

According to an aspect of the present invention, there is provided a method for managing a hybrid-electric powerplant (HEP) comprising a thermal engine and an electric motor in accordance with claim <NUM>.

According to another aspect of the present invention, there is provided a power management system for a hybrid-electric powerplant (HEP) comprising a thermal engine and an electric motor in accordance with claim <NUM>.

The present disclosure is directed to power management for a hybrid-electric powerplant (HEP), such as those used in an aircraft propulsion system. On a traditional thermal engine, there is only one source of power. In the event of a fault affecting power output from the thermal engine or its associated control, there is no way to supplement power. With an HEP, power deviations from one power source may be mitigated by increasing or decreasing the power output from the other power source to accommodate the fault.

An example HEP <NUM> is shown in <FIG> and generally comprises a thermal engine <NUM>, an electric motor <NUM> and a propeller <NUM>. The thermal engine <NUM> is, in this example, a combustion engine, and more particularly a turbine turboprop engine. Other types of combustion engines, such as turboshaft, turbofan turbine engines, and internal combustion engines, may also apply. Generally, the thermal engine <NUM> may be any system that converts heat or thermal energy to mechanical energy which can then be used to drive a load, such as the propeller <NUM>. The load can also be a fan, rotor system, and the like. The electric motor <NUM> may be any type of electric motor, including an electric machine that can be driven as a motor or as a generator.

The propeller <NUM> is attached to a shaft <NUM> through which ambient air is propelled. There is provided in serial flow communication a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases driving the rotation of the propeller through the shaft <NUM>. The propeller <NUM> converts rotary motion from the shaft <NUM> of the engine <NUM> to provide propulsive force for the aircraft, also known as thrust. The propeller <NUM> may be a variable-pitch propeller capable of generating forward and reverse thrust and comprises two or more propeller blades <NUM>. For a propeller-driven propulsion system, the thermal engine <NUM> drives the propeller <NUM> via a reduction gear box (RGB) <NUM>.

Also coupled to the RGB <NUM> is the electric motor <NUM>, which uses electricity to provide power that is converted to thrust via the RGB <NUM> towards the propeller <NUM>. The HEP <NUM> thus includes two power sources, namely the electric motor <NUM> and the thermal engine <NUM>, whose power is combined through the RGB <NUM> and used to drive the load (i.e. propeller <NUM>). While the thermal engine <NUM> and the electric motor <NUM> are shown in this example to be coupled to the propeller <NUM> through the RGB <NUM>, other configurations are also contemplated. For example, in a pusher-puller configuration, a propulsion unit having a thermal engine and an electric motor may be coupled to one or more loads without a gear box.

Referring to <FIG>, a power management system <NUM> is coupled to the HEP <NUM>, which includes the thermal engine <NUM>, electric motor <NUM>, and a combining gearbox <NUM> (which can also provide the mechanical speed reduction typically provided by the reduction gearbox <NUM>). A power request is received, for example from a power throttle <NUM> in an aircraft cockpit, at the power management system <NUM>. The power throttle <NUM> may be a power lever or a collective lever, and may provide a power lever angle or throttle lever angle representative of the power request. In some embodiments, the total power request may come from another aircraft or avionic system, or from an engine system or controller. For example, the power request may be sent from the power throttle <NUM> to another system which may then provide the information to the power management system <NUM>. The power management system <NUM> converts the total power request into an electric power request and a thermal power request in accordance with a desired proportion of electric power and thermal power. The electric power request and thermal power requests are then converted into an electric power command and a thermal power command, respectively, which are used to drive the electric motor <NUM> and thermal engine <NUM>, respectively. It will be understood that the breakdown between thermal power and electric power may vary anywhere between <NUM>% to <NUM>% for either power source.

In some embodiments, two separate power lanes are provided from the power management system <NUM> to the HEP <NUM>, one for the thermal power command and one for the electric power command, and are referred to herein as the thermal power lane and the electric power lane, respectively. The actual power output by the HEP <NUM> for each power source is provided to the power management system <NUM>. The power management system <NUM> is configured to detect faults that have the potential to affect the power command or power output to a given power lane by comparing a given power command to an actual output power. A fault in the electric power lane is detected when the electric power output deviates from the electric power command by more than a first threshold. A fault in the thermal power lane is detected when the thermal power output deviates by the thermal power command by more than a second threshold. The first and second thresholds may be the same or different, taking into account the differences between the thermal engine <NUM> and the electric motor <NUM>. The fault may be confirmed using a timer, i.e. the deviation is maintained for a predetermined time.

In the event of a fault in one of the two power lanes, the power management system <NUM> is configured to modulate the power command of the unfaulted power lane to accommodate the fault. If the thermal power output is higher than it should be based on the thermal power command, the electric power command may be reduced to account for the deviation in the thermal power command or output. The electric motor <NUM> provides a braking force to reduce the total power output by the HEP <NUM>, or consume excess power to recharge batteries. It may be sufficient to simply reduce the electric power command. Similarly, if the thermal power output is lower than it should be based on the thermal power command, the electric power command may be increased to account for the deviation in the thermal power command or output. If the electric power output deviates from the electric power command by more than a threshold, the thermal power command may be modulated to accommodate the fault by providing more or less thermal power output in accordance with the deviation of the electric power command or output. The ability to accommodate the fault in the faulted power lane through the unfaulted power lane may depend on a variety of circumstances, such as ambient conditions, aircraft operating conditions, powertrain operating conditions, power lane operating conditions, and the like.

In some embodiments, the power management system <NUM> is implemented within a single controller <NUM>. The controller may be multi channel or single channel, each channel having one or more processor, each processor having one or more core. Various functions of the system <NUM> may be split across channels and/or processors and/or cores. For example, a first channel may convert the thermal power request to a thermal power command while a second channel may convert the electric power request to an electric power command. Similarly, a first processor or first core may convert the thermal power request to a thermal power command while a second processor or core may convert the electric power request to an electric power command. Fault detection and fault accommodation may be provided in a same or separate channel, processor, and/or core.

In some embodiments, and as illustrated in the example of <FIG>, the power management system <NUM> comprises a first controller and a second controller, with each controller dedicated to one of the thermal engine <NUM> and the electric motor <NUM>. A thermal engine controller <NUM> receives the thermal power request and determines the thermal power command based on the thermal power request. In some embodiments, other parameters such as aircraft parameters, thermal engine parameters, and ambient operating conditions may be used to determine the thermal power command. Examples of aircraft parameters include but are not limited to flight phase, aircraft weight, fuel status, battery state of charge, weight on wheels, flap setting, and secondary system requests (e.g. bleed system, hydraulic drive system, electrical power generation system). Examples of engine parameters include but are not limited to temperature, rotational speed, pressure, fuel rate, output torque, and internal system operating conditions. Examples of ambient operating conditions include but are not limited to outside air temperature, altitude, Mach number, calibrated air speed, and ambient pressure. An electric motor controller <NUM> receives the electric power request and determines the electric power command based on the electric power request. In some embodiments, other parameters such as the aircraft parameters, electric motor parameters, and the ambient operating conditions may be used to determine the thermal power command. Examples of the electric motor parameters include but are not limited to voltage, current, torque, speed, power factor, efficiency, internal temperature, and internal resistance.

In some embodiments, a third controller is provided in the power management system <NUM> for converting the total power request into the thermal power request and the electric power request. For example, a power controller <NUM> may be found upstream from the thermal engine controller <NUM> and the electric motor controller <NUM> to perform this function. Alternatively, the power controller <NUM> may form part of the thermal engine controller <NUM> or the electric motor controller <NUM> instead of being provided separately therefrom.

As stated above, fault detection is performed by comparing an actual power output to a corresponding power command for a given power source. In some embodiments, each controller <NUM>, <NUM> is configured to perform fault detection for its own power lane in a form of self-diagnosis. For example, the thermal engine controller <NUM> may receive the thermal power output from the HEP <NUM> and compare the thermal power output to its own thermal power command to detect a fault. Similarly, the electric motor controller <NUM> may receive the electric power output from the HEP <NUM> and compare the electric power output to its own electric power command to detect a fault. Upon detection of a fault, the controller <NUM>, <NUM> that detects the fault may send a fault flag to the other controller <NUM>, <NUM>. This may be used as a flag to determine if fault accommodation should be performed, especially during critical flight phases. Fault accommodation would then be performed by the controller <NUM>, <NUM> having an unfaulted power lane.

Alternatively or in combination therewith, each controller <NUM>, <NUM> is configured to perform fault detection for the other controller <NUM>, <NUM>. For example, the electric motor controller <NUM> may compare the thermal power output to the thermal power command. The thermal power command may be provided to the electric motor controller <NUM> by the power controller <NUM> or by the thermal engine controller <NUM>. Alternatively, the electric motor controller <NUM> may calculate the thermal power command based on the thermal power request, which it may receive from the power controller <NUM> or the thermal engine controller <NUM>. Also alternatively, the electric motor controller <NUM> may calculate the thermal power request based on the electric power request and the total power request, which it may receive from the power controller <NUM> or the thermal engine controller <NUM>. Any one of the total power request, the thermal power request, and the electric power request may be calculated by either controller <NUM>, <NUM> based on the other two of these. Any one of the total power output, the electric power output, and the thermal power output may be calculated by either controller <NUM>, <NUM> based on the other two of these. Therefore, it will be understood that the embodiment illustrated in <FIG> is merely an example and other embodiments may also apply.

The controller <NUM>, <NUM> of the unfaulted power lane may consider the total power request to modulate its own power command once a fault has been detected. For example, the controller <NUM>, <NUM> may modulate its own power command so as to generate the total power requested. The controller <NUM>, <NUM> may also consider additional factors to determine how much of the total power request it should generate as it accommodates the fault in the faulted power lane. For example, fuel consumption rate, remaining fuel level, and remaining distance to travel may be considered by the thermal engine controller <NUM>, while battery state of charge may be considered by the electric motor controller <NUM>. There may be specific settings for each controller that dictate how to modulate its own power command when accommodating a fault in a power lane. For example, there may be a setting to enable modulation of the power command during certain phases of flight of the aircraft. There may be a setting to disable or limit modulation of the power command in certain circumstances, such as in certain areas of the flight envelope where it may be unsafe to do so, such as takeoff and go-around. Power modulation may be limited to only reducing an own power command, or to increasing by no more than a certain percentage of an original power command. In some embodiments, an enablement/disablement signal may be received from a pilot commanded switch in a cockpit of the aircraft. Other embodiments are also contemplated depending on practical implementation.

With reference to <FIG>, there is illustrated a method <NUM> for managing an HEP comprising a thermal engine and an electric motor, as performed by the power management system <NUM> of <FIG> or <FIG>. At step <NUM>, the total power request is received and the thermal power request and electric power request are determined based on the total power request. In some embodiments, a pre-determined breakdown is used to determine the thermal power request and electric power request. Alternatively, various parameters may be used to determine the breakdown. At step <NUM>, the thermal and electric power requests are converted into respective power commands. Various aircraft, engine and operating conditions may be used for this conversion. At step <NUM>, the thermal and electric power commands are transmitted to the thermal engine and electric motor of the HEP, respectively.

At step <NUM>, the power management system <NUM> compares the thermal power output by the thermal engine to the thermal power command, and compares the electric power output by the electric motor to the electric power command. At step <NUM>, a fault is detected when the thermal power output deviates from the thermal power command by more than a first threshold or when the electric power output deviates from the electric power command by more than a second threshold. In response to detecting the fault, the power command for one of the two power sources is modulated at step <NUM>. More specifically, the thermal power command is modulated in case of an electric power output deviation and the electric power command is modulated in case of a thermal power output deviation.

As stated above, various architectures are contemplated for the power management system <NUM>, including having a single controller, dedicated power source controllers (i.e. one for the thermal engine and one for the electric motor), and three controllers (as per <FIG>). In an architecture having at least two controllers, each power source controller may detect a fault in itself and/or in the other controller. Faults may be flagged by the controller detecting the fault to the other controller(s). Each controller may be configured to determine how it can reduce a total power output by the HEP in response to a fault causing an increase to the total power output. Each controller may be configured to determine if it can provide additional power to meet the total power request in response to a fault causing a decrease to a total power output by the HEP. In some embodiments, the power management system functions are contained entirely within the thermal engine controller <NUM> or the electric motor controller <NUM>.

Power modulation may be capped or limited in one direction, i.e. up or down. Power modulation may be determined as a function of the total power request and/or other factors or parameters. Power modulation may be enabled and/or disabled in certain circumstances, based on flight envelope, flight phase, and other mitigating factors.

The power management system <NUM> may be implemented with one or more computing device <NUM>, an example of which is illustrated in <FIG>. For simplicity only one computing device <NUM> is shown but, for example, each controller <NUM>, <NUM>, <NUM> may be implemented by one or more of the computing devices <NUM>. The computing devices <NUM> may be the same or different types of devices. Note that the thermal engine controller <NUM> and/or power controller <NUM> can be implemented as part of a full-authority digital engine controls (FADEC) or other similar device, including electronic engine control (EEC), engine control unit (ECU), electronic propeller control, propeller control unit, and the like. The motor controller <NUM> can be implemented as part of a motor controller (MC), electric motor controller (EMC), electric powertrain controller (EPC), and the like. Other embodiments may also apply.

The methods and systems for power management of an HEP described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device <NUM>. Alternatively, the methods and systems for power management may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for power management may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems for power management may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit <NUM> of the computing device <NUM>, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method <NUM>.

Claim 1:
A method (<NUM>) for managing a hybrid-electric powerplant, HEP, (<NUM>) comprising a thermal engine (<NUM>) and an electric motor (<NUM>), the method comprising:
receiving (<NUM>) a total power request for the HEP (<NUM>) and determining, from the total power request, a thermal power request and an electric power request;
converting (<NUM>) the thermal power request into a thermal power command and the electric power request into an electric power command;
transmitting (<NUM>) the thermal power command to the thermal engine (<NUM>) to generate a thermal power output;
transmitting (<NUM>) the electric power command to the electric motor (<NUM>) to generate an electric power output;
comparing (<NUM>) the thermal power output to the thermal power command and the electric power output to the electric power command;
detecting (<NUM>) a fault when the thermal power output deviates from the thermal power command by more than a first threshold or when the electric power output deviates from the electric power command by more than a second threshold; and
accommodating (<NUM>) the fault by modulating the thermal power command in response to the electric power output deviating from the electric power command by more than the first threshold and modulating the electric power command in response to the thermal power output deviating from the thermal power command by more than the second threshold,
characterised in that:
modulating the electric power command includes providing a braking force using the electric motor (<NUM>) to reduce a total power output from the HEP (<NUM>) if the thermal power output is higher than it should be based on the thermal power output command.