Patent Publication Number: US-2022234748-A1

Title: Methods and systems for power management of a hybrid electric powerplant

Description:
TECHNICAL FIELD 
     The disclosure relates generally to power management and, more particularly, to power management of a hybrid electric powerplant having an electric motor and a thermal engine. 
     BACKGROUND OF THE ART 
     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. 
     SUMMARY 
     In one aspect, there is provided a method for managing a hybrid-electric powerplant (HEP) comprising a thermal engine and an electric motor are described. The method comprises receiving a total power request for the HEP and determining, from the total power request, a thermal power request and an electric power request; converting the thermal power request into a thermal power command and the electric power request into an electric power command; transmitting the thermal power command to the thermal engine to generate a thermal power output; transmitting the electric power command to the electric motor to generate an electric power output; comparing the thermal power output to the thermal power command and the electric power output to the electric power command; detecting 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 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. 
     In another aspect, there is provided a power management system for a hybrid-electric powerplant (HEP) comprising a thermal engine and an electric motor. The power management system comprises at least one controller having at least one processor and a memory coupled thereto, the memory having stored thereon program instructions. The program instructions are executable by the processor for receiving a total power request for the HEP and determining, from the total power request, a thermal power request and an electric power request; converting the thermal power request into a thermal power command and the electric power request into an electric power command; transmitting the thermal power command to the thermal engine to generate a thermal power output; transmitting the electric power command to the electric motor to generate an electric power output; comparing the thermal power output to the thermal power command and the electric power output to the electric power command; detecting 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 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. 
     The features described herein may be used together in any combination. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG. 1  is a schematic cross sectional view of a hybrid electric powerplant; 
         FIG. 2  is a block diagram of the hybrid electric powerplant and power management system; 
         FIG. 3  is a block diagram of an example embodiment of the power management system; 
         FIG. 4  is a flowchart an example method of power management for a hybrid electric powerplant; and 
         FIG. 5  is a block diagram of an example computing device. 
     
    
    
     DETAILED DESCRIPTION 
     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  100  is shown in  FIG. 1  and generally comprises a thermal engine  110 , an electric motor  130  and a propeller  120 . The thermal engine  110  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  110  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  120 . The load can also be a fan, rotor system, and the like. The electric motor  130  may be any type of electric motor, including an electric machine that can be driven as a motor or as a generator. 
     The propeller  120  is attached to a shaft  108  through which ambient air is propelled. There is provided in serial flow communication a compressor section  114  for pressurizing the air, a combustor  116  in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section  106  for extracting energy from the combustion gases driving the rotation of the propeller through the shaft  108 . The propeller  120  converts rotary motion from the shaft  108  of the engine  110  to provide propulsive force for the aircraft, also known as thrust. The propeller  120  may be a variable-pitch propeller capable of generating forward and reverse thrust and comprises two or more propeller blades  122 . For a propeller-driven propulsion system, the thermal engine  110  drives the propeller  120  via a reduction gear box (RGB)  132 . 
     Also coupled to the RGB  132  is the electric motor  130 , which uses electricity to provide power that is converted to thrust via the RGB  132  towards the propeller  120 . The HEP  100  thus includes two power sources, namely the electric motor  130  and the thermal engine  110 , whose power is combined through the RGB  132  and used to drive the load (i.e. propeller  120 ). While the thermal engine  110  and the electric motor  130  are shown in this example to be coupled to the propeller  120  through the RGB  132 , 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. 2 , a power management system  200  is coupled to the HEP  100 , which includes the thermal engine  110 , electric motor  130 , and a combining gearbox  232  (which can also provide the mechanical speed reduction typically provided by the reduction gearbox  132 ). A power request is received, for example from a power throttle  202  in an aircraft cockpit, at the power management system  200 . The power throttle  202  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  202  to another system which may then provide the information to the power management system  200 . The power management system  200  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  130  and thermal engine  110 , respectively. It will be understood that the breakdown between thermal power and electric power may vary anywhere between 0% to 100% for either power source. 
     In some embodiments, two separate power lanes are provided from the power management system  200  to the HEP  100 , 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  100  for each power source is provided to the power management system  200 . The power management system  200  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  110  and the electric motor  130 . 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  200  is configured to modulate the power command of the unfaulted power lane to accommodate the fault. For example, 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  130  may provide a braking force to reduce the total power output by the HEP  100 , or consume excess power to recharge batteries. In some embodiments, 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  200  is implemented within a single controller  204 . 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  200  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. 3 , the power management system  200  comprises a first controller and a second controller, with each controller dedicated to one of the thermal engine  110  and the electric motor  130 . A thermal engine controller  302  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  304  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  200  for converting the total power request into the thermal power request and the electric power request. For example, a power controller  306  may be found upstream from the thermal engine controller  302  and the electric motor controller  304  to perform this function. Alternatively, the power controller  306  may form part of the thermal engine controller  302  or the electric motor controller  304  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  302 ,  304  is configured to perform fault detection for its own power lane in a form of self-diagnosis. For example, the thermal engine controller  302  may receive the thermal power output from the HEP  100  and compare the thermal power output to its own thermal power command to detect a fault. Similarly, the electric motor controller  304  may receive the electric power output from the HEP  100  and compare the electric power output to its own electric power command to detect a fault. Upon detection of a fault, the controller  302 ,  304  that detects the fault may send a fault flag to the other controller  302 ,  304 . 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  302 ,  304  having an unfaulted power lane. 
     Alternatively or in combination therewith, each controller  302 ,  304  is configured to perform fault detection for the other controller  302 ,  304 . For example, the electric motor controller  304  may compare the thermal power output to the thermal power command. The thermal power command may be provided to the electric motor controller  304  by the power controller  306  or by the thermal engine controller  302 . Alternatively, the electric motor controller  304  may calculate the thermal power command based on the thermal power request, which it may receive from the power controller  306  or the thermal engine controller  302 . Also alternatively, the electric motor controller  304  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  306  or the thermal engine controller  302 . Any one of the total power request, the thermal power request, and the electric power request may be calculated by either controller  302 ,  304  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  302 ,  304  based on the other two of these. Therefore, it will be understood that the embodiment illustrated in  FIG. 3  is merely an example and other embodiments may also apply. 
     The controller  302 ,  304  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  302 ,  304  may modulate its own power command so as to generate the total power requested. The controller  302 ,  304  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  302 , while battery state of charge may be considered by the electric motor controller  304 . 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. 4 , there is illustrated a method  400  for managing an HEP comprising a thermal engine and an electric motor, as performed by the power management system  200  of  FIG. 2 or 3 . At step  402 , 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  404 , 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  406 , the thermal and electric power commands are transmitted to the thermal engine and electric motor of the HEP, respectively. 
     At step  408 , the power management system  200  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  410 , 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  412 . 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  200 , 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. 3 ). 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 determines 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  302  or the electric motor controller  304 . 
     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  200  may be implemented with one or more computing device  500 , an example of which is illustrated in  FIG. 5 . For simplicity only one computing device  500  is shown but, for example, each controller  302 ,  304 ,  306  may be implemented by one or more of the computing devices  500 . The computing devices  500  may be the same or different types of devices. Note that the thermal engine controller  302  and/or power controller  306  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  304  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 computing device  500  comprises a processing unit  502  and a memory  504  which has stored therein computer-executable instructions  506 . The processing unit  502  may comprise any suitable devices configured to implement the method  400  such that instructions  506 , when executed by the computing device  500  or other programmable apparatus, may cause the functions/acts/steps performed as part of the method  400  as described herein to be executed. The processing unit  502  may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof. 
     The memory  504  may comprise any suitable known or other machine-readable storage medium. The memory  504  may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory  504  may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory  504  may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions  506  executable by processing unit  502 . 
     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  500 . 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  502  of the computing device  500 , to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method  400 . 
     Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. 
     The embodiments described herein are implemented by physical computer hardware, including computing devices, servers, receivers, transmitters, processors, memory, displays, and networks. The embodiments described herein provide useful physical machines and particularly configured computer hardware arrangements. The embodiments described herein are directed to electronic machines and methods implemented by electronic machines adapted for processing and transforming electromagnetic signals which represent various types of information. The embodiments described herein pervasively and integrally relate to machines, and their uses; and the embodiments described herein have no meaning or practical applicability outside their use with computer hardware, machines, and various hardware components. Substituting the physical hardware particularly configured to implement various acts for non-physical hardware, using mental steps for example, may substantially affect the way the embodiments work. Such computer hardware limitations are clearly essential elements of the embodiments described herein, and they cannot be omitted or substituted for mental means without having a material effect on the operation and structure of the embodiments described herein. The computer hardware is essential to implement the various embodiments described herein and is not merely used to perform steps expeditiously and in an efficient manner. 
     The term “connected” or “coupled to” may include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). 
     The technical solution of embodiments may be in the form of a software product. The software product may be stored in a non-volatile or non-transitory storage medium, which can be a compact disk read-only memory (CD-ROM), a USB flash disk, or a removable hard disk. The software product includes a number of instructions that enable a computer device (personal computer, server, or network device) to execute the methods provided by the embodiments. 
     The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. For example, modulation of the power command may be enabled upon detection of an uncontrolled high thrust (UHT) event, to decrease the total power output by the HEP  100 . Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.