Patent ID: 12227166

DETAILED DESCRIPTION

Vehicles may include combustion motors that convert chemical potential energy (e.g., fuel) to propulsion and/or to electrical power. In addition to combustion motors, vehicles may include electric machines to create propulsion. A vehicle that includes both combustion motors and electric machines may be referred to as a hybrid vehicle. The motors in hybrid vehicles may be configured as series, parallel, or series-parallel.

Combustion motor(s) may not directly provide power to propulsors, but instead may provide power in the form of rotational mechanical energy to one or more electric generators. The generator(s) may provide electrical power to the electric machine(s), which in turn provide power (i.e., rotational mechanical energy) to one or more propulsors. In some examples, a vehicle may include an ESS capable of storing electrical energy for subsequent use by the electric machines. The ESS may be charged with electrical energy generated by the generator(s) using mechanical energy from the combustion motor(s), electrical energy received from a source external to the vehicle (e.g., ground power in the case of an aircraft), and/or electrical energy generated by one or more other components of the vehicle. Some other components of the vehicle that may generate electrical energy include, but are not limited to, the electric machines (e.g., in a descent phase of flight in the case of an aircraft), solar panels, and the like.

The presence of multiple sources of electrical power allows for control over the use of the multiple sources to meet a request for power, e.g., a power demand, such as an amount of power to be used to propel a vehicle. In some examples, a power sharing scheme between one or more generators and one or more ESS may be used to provide power to one or more electric machines to propel a vehicle.

FIG.1is a conceptual diagram of a hybrid vehicle100that includes a power-sharing controller, in accordance with one or more techniques of this disclosure. In some examples, vehicle100includes an aircraft. In other examples, vehicle100may include any type of vehicle utilizing an electric machine, including one or more types of air vehicles; land vehicles, including but not limited to, tracked and/or wheeled vehicles; marine vehicles, including but not limited to surface vessels, submarines, and/or semi-submersibles; amphibious vehicles; or any combination of one or more types of air, land, and marine vehicles. Vehicle100may be manned, semiautonomous, or autonomous.

As shown in the example ofFIG.1, vehicle100may include propulsion system102. In some examples, propulsion system102may include a combustion engine, such as a gas-turbine engine. Propulsion system102includes motor104that is configured to drive propulsor130. Propulsion systems that include gas-turbine engines may include electric generator108that may both start the gas-turbine engines and generate electrical power using mechanical energy generated by the gas-turbine engines. As shown inFIG.1, propulsion system102may include generator108and ESS110coupled to electrical bus114, and motor104coupled to electrical bus114.

In accordance with one or more techniques of this disclosure, vehicle100may include components configured to control electrical power sourcing of generator108and ESS110. For instance, a controller may determine a first amount of power of an amount of power to be used to propel vehicle100to be sourced from ESS110, and a second amount of power of the amount of power to be used to propel vehicle100to be sourced from generator108. One or more processors of vehicle100, e.g., included in the controller, may determine the first and second amounts of power sourced via ESS110and generator108, respectively, based on a predetermined ESS output limit.

FIG.2is a conceptual block diagram illustrating a system2that includes a hybrid propulsion system, in accordance with one or more techniques of this disclosure. As shown inFIG.2, system2includes an electrical bus4, one or more power units6A-6N (collectively, “power units6”), one or more propulsion modules12A-12N (collectively, “propulsion modules12”), an ESS34, and a controller36. System2may be included in, and provide propulsion to, any vehicle, such as an aircraft, a locomotive, or a watercraft. System2may include additional components not shown inFIG.2or may not include some components shown inFIG.2.

Electrical bus4provides electrical power interconnection between various components of system2. Electrical bus4may include any combination of one or more direct current (DC) bus, one or more alternating current (AC) electrical bus, or combinations thereof. As one example, electrical bus4may include a DC bus configured to transport electrical power between power units6and propulsion modules12. As another example, electrical bus4may include a plurality of redundant DC buses configured to transport electrical power between power units6and propulsion modules12.

Power units6provide electrical power for use by various components of system2. As shown inFIG.2, each of power units6includes one or more combustion motors and one or more associated electric machines. For instance, power unit6A includes combustion motor8A and electric machine10A, and power unit6N includes combustion motor8N and electric machine10N. In operation, combustion motor8A utilizes fuel to produce rotational mechanical energy, which may be provided to electric machine10A via drive shaft7A. Electric machine10A converts the rotational mechanical energy into electrical energy and outputs the electrical energy to electrical bus4. Each of the combustion motors included in power units6may be any type of combustion motor. Examples of combustion motors include, but are not limited to, reciprocating, rotary, and gas-turbines. In some examples, one or more of power units6may be a turbogenerator.

Each of power units6may have the same or different power generation capacities. As one example, when operating at peak power, power unit6A may be capable of generating a greater amount of electrical power than power unit6N. In this way, one or more of power units6A-6N may be enabled, e.g., depending on a power demands of propulsion modules12, other components of system2, or both. As another example, when operating at peak power, power unit6A and power unit6N may be capable of generating the same amount of electrical power.

Power units6may have an output power limit that is less than their respective peak powers or full output power capacity. For example, a power unit output limit may be predetermined and based on power unit type, combustion motor type, electric machine type, and/or other components which may degrade, fail, or otherwise adversely affect the power unit if the power unit was allowed to operate at peak power for extended periods of time or without constraint. In other examples, a power unit output limit may be determined based on hours of operation of the power unit, determined condition of the power unit and/or its constituent components, and/or environmental conditions. For example, one or more components of system2, e.g., controller36, may determine the output power limits corresponding to each of power units6. Power units6may have output power margin between their respective peak powers and output power limits and may override their respective output power limits and operate at up to their peak powers, for example, for propulsion power demands.

Propulsion modules12convert electrical energy to propulsion. As shown inFIG.2, each of propulsion modules12may include one or more electric machines and one or more propulsors. For instance, propulsion module12A includes electric machine14A and propulsor16A, and propulsion module12N includes electric machine14N and propulsor16N. In operation, propulsion modules12may operate in a plurality of modes including, but not limited to, an motoring mode, a regeneration mode, and a neutral mode.

When propulsion module12A operates in the motoring mode, electric machine14A may consume electrical energy received via electrical bus4and convert the electrical energy to rotational mechanical energy to power propulsor16A. When propulsion module12A operates in the regeneration mode, electric machine14A converts rotational mechanical energy received from propulsor16A into electrical energy and provides the electrical energy to electrical bus4. Electrical bus4may distribute the electrical energy to another one of propulsion modules12, ESS34, or combinations thereof. When propulsion module12A operates in the neutral mode, propulsor16A may reduce its fluid resistance (e.g., feather and/or blend with contours of an airframe).

Each of propulsion modules12may have the same or different propulsion capacities. As one example, when operating at peak power, propulsion module12A may be capable of generating more propulsive power than propulsion module12N. As another example, when operating at peak power, propulsion module12A may be capable of generating the same amount of propulsive power as propulsion module12N. As another example, propulsion module12A may positioned at an outboard portion of a wing to provide greater yaw control while propulsion module12N may be positioned at an inboard portion of the wing in order to provide primary propulsion.

For modules that include electric machines and combustion motors (i.e., power units6), the electric machines may be discrete components included in their own housing, or may be integral to (i.e., included/embedded in) a same housing as the combustion motors. As one example, electric machine10A may be included in same housing and/or directly mounted to combustion motor8A. As another example, electric machine10A may be attached to combustion motor8A via a drive shaft.

Additionally, for modules that include electric machines and combustion motors, the modules may include an additional starter, be started by their respective electric machine(s) or be started through some other means. As one example, combustion motor8A may include a starter that is different than electric machine10A. As another example, electric machine10A may operate as a starter for combustion motor8A.

ESS34may provide energy storage capacity for system2. ESS34may include any devices or systems capable of storing energy (e.g., electrical energy). Examples of devices that may be included ESS34include, but are not limited to, batteries, capacitors, supercapacitors, flywheels, pneumatic storage, and any other device capable of storing electrical energy or energy that may be converted to electrical energy (without combustion). ESS34may be coupled to electrical bus4and may be capable of providing electrical energy to electrical bus4and receiving electrical energy (e.g., for charging) from electrical bus4.

In some examples, ESS34may include multiple energy storage systems. For instance, ESS34may include a first energy storage system configured to store and provide electrical energy for propulsion and a second energy storage system configured to store and provide electrical energy for other systems, such as avionics and/or hotel loads. In some examples, ESS34may include a single energy storage system. For instance, ESS34may include a single energy storage system configured to store and provide electrical energy for propulsion and other systems.

In some examples, one or more components of ESS34may be swappable. For example, one or more batteries of ESS34may be swappable while an aircraft including system2is on the ground. As such, the aircraft may be quickly able to return to a fully charged state without the need to charge the batteries on the ground.

Controller36may control the operation of one or more components of system2. For instance, controller36may control the operation of electrical bus4, power units6, propulsion modules12, and ESS34. In some examples, controller36may include a single controller that controls all of the components. In other examples, controller36may include multiple controllers that each control one or more components. Where controller36includes multiple controllers, the controllers may be arranged in any configuration. As one example, controller36may include a separate controller for each module type. For instance, controller36may include a first controller that controls power units6and a second controller that controls propulsion modules12. As another example, controller36may include a separate controller for each module, or sub-module, within the module types. For instance, controller36may include a separate controller for each of power units6and a separate controller for each of propulsion modules12.

In some examples, controller36may determine the sourcing of electrical power to meet a power demand, for example, a request for power for an amount of power to be used to propel a vehicle. In some examples, controller36may receive a power demand, via one or more processor, specifying an amount of power to be used to propel a vehicle. Controller36may determine a first amount of power to be sourced from ESS34and second amount of power to be sourced from one or more generators, e.g., power units6A,6N. Controller36may determine the first and second amounts of power based on a predetermined ESS output limit, as illustrated and described below with respect toFIGS.3-12.

Controller36may comprise any suitable arrangement of hardware, software, firmware, or any combination thereof, to perform the techniques attributed to controller36herein. Examples of controller36include any one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. When controller36includes software or firmware, controller36further includes any necessary hardware for storing and executing the software or firmware, such as one or more processors or processing units. In some examples, controller36may be a full authority digital engine controller (FADEC).

In general, a processing unit may include one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. Although not shown inFIG.2, controller36may include a memory configured to store data. The memory may include any volatile or non-volatile media, such as a random access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, and the like. In some examples, the memory may be external to controller36(e.g., may be external to a package in which controller36is housed).

In some examples, ESS34and/or power units6may include individual controllers (not shown), e.g., such that at least some of the functions of ESS34and/or power units6are controlled by their respective individual controller alone or in combination with controller36. For example, ESS34may include a local controller to control charge current, discharge current, protection functions such as overcurrent disconnect and the like, controlling charge and discharge limits, etc. Power units6may include a local controller to control voltage, torque, speed, gate switching, protection functions, limits, regulating current, and the like.

In operation, system2may include and be propelled by any combination of propulsion modules12, one or more power units6, and ESS34.

Where multiple propulsion modules are present (e.g., multiple instances of a specific type of propulsion module, multiple different types of propulsion modules, or combinations thereof), the multiple propulsion modules may be controlled independently, collectively in groups, or completely collectively. As one example, in an example where system2includes multiple propulsion modules12, each of propulsion modules12may be independently controlled. As another example, in an example where system2includes multiple propulsion modules12, all of propulsion modules12may be collectively controlled. As another example, in an example where system2includes multiple propulsion modules12, a first set of propulsion modules12may be collectively controlled and a second set of propulsion modules12may be collectively controlled independently from the first set of propulsion modules12.

FIG.3is a conceptual block diagram illustrating a system300that includes a hybrid propulsion system and a controller36, in accordance with one or more techniques of this disclosure. System300may represent one example of system2ofFIG.2that includes controller36, power unit6A, ESS34, propulsion module12A, and electrical bus4providing an electrical power interconnection between power unit6A, ESS34, and propulsion module12A. System300may also include system state manager302and motor demand manager304, and source demand manager308, the functions of any of which may be performed by controller36. Although the example system300illustrated inFIG.3shows a single ESS34, power unit6A, and propulsion module12A, in some examples system300may include one or more of each of ESS34, power unit6A, and propulsion module12A.

System state manager302provides information to one or more controllers and/or system managers relating to the state and mode of a plurality of control switches and settings of various vehicle systems. For example, system state manager302may receive throttle input relating to propulsion, and output information relating to throttle input to controller36and motor demand manager304, such as the state and mode of throttle input. In some examples, system state manager302may receive switch input such as user input relating to one or more systems of the vehicle. For example, system state manager302may receive switch input relating to hotel loads, communications, mechanical systems and the like, and may output information relating to the received input to the appropriate system and/or controller controlling the appropriate system. In some examples, system state manager302may receive feedback from various components of system300, such as ESS34, power unit6A, and propulsion module12A. For example, system state manager302may receive information relating to device status, state, contactor status, speed, voltage, and the like.

Motor demand manager304provides information and control commands to propulsion module12A. For example, motor demand manager304may receive information relating to throttle input including throttle state and mode from system state manager302and output information, such as propulsion module12A mode, and control commands such as a specified torque and/or speed of electric machine14A. In some examples, motor demand manager304may receive throttle input directly and output information and commands. In some examples, motor demand manager304may receive information from one or more source demand managers308, such as limits on propulsion module12A, and output information and commands.

Source demand manager308may control the operation of one or more components of system300and system2, as described above with respect toFIG.2. For example, source demand manager308may receive input information and commands from system state manager302, such as one or more states and modes, and other inputs, such as power share request306. Source demand manager308may output information and control commands, such as mode and electrical current demand, to ESS34and/or power unit6A. source demand manager308may receive information from ESS34and/or power unit6A, for example, feedback relating to electrical current, limits of ESS34and power unit6A, engine temperatures and pressures, and the like. In some examples, limits of various components of system300, e.g., ESS34, power unit6A, propulsion module12A, may include predetermined output limits which may be set and/or changed. Limits may also include the output capability and/or capacity limits of various components of system300, e.g., the maximum output of ESS34and/or power unit6A, which may change depending on environmental conditions, faults and/or fault conditions, material degradation of ESS34and/or power unit6A, and the like.

Controller36may determine a first amount of power to be sourced from ESS34and second amount of power to be sourced from power unit6A to meet a power demand and/or request for power for an amount of power to be used to propel the vehicle. In some examples, controller36may determine a plurality of amounts of power to be sourced from a plurality of ESS's and power units. In some examples, controller36may determine the first and second amounts of power based on any or all of the power demand, power share request306, and feedback information including electrical current feedback and limits of various components of system300, e.g., ESS34, power unit6A, and propulsion module12A. Controller36may output the determined first amount of power to ESS34and the determined second amount of power to power unit6A. In some examples, controller36may output limits to motor demand manager304and may receive information relating to feed-forwarding from motor demand manager304. For example, motor demand manager304may apply limits to the power demanded by pilot throttles so that the motor demand cannot exceed the total power available, e.g. due to degraded components. This total power available limit may be determined by source demand manager308using system status information such as fixed predetermined limits, state and mode information from the system state manager302, limit feedback from the ESS34and power unit6A, as well as combustion engine temperatures and pressures from power unit6A (which may define engine limits).

Power share request306may provide a criteria for sourcing of the electrical power of system300and setting output limits for ESS34and/or power unit6A. For example, the amount of power of a power demand supplied by each of ESS34and power unit6A may be determined based on power share request306. In some examples, a predetermined ESS limit may be determined based on power share request306, and in some examples the predetermined ESS limit may be power share request306. In some examples, power share request306may correspond to a percentage of a fixed power demand, e.g., a fixed request for power and/or a total power required. In some example, controller36may receive a plurality of power share requests306, for example, a power share request for each of a plurality of ESS's and power units. In some examples, a user may input a power share request, for example, via a dial, lever, touch screen input, typed input, or any other appropriate means. In other examples, a power share request may be determined via a control algorithm and/or a schedule.

FIGS.4-6illustrate an example sequential power management method600and are described concurrently with reference to each other below.

FIG.4is an example plot400illustrating example power output as a function of power demand curves402-406for a power share request of 67%, in accordance with one or more techniques of this disclosure. In the example shown, total power curve402is the sum of power unit curve404and ESS curve406, with power unit6A providing up to 70% of the total available power and ESS34providing up to 30% of the total available power, e.g., a 70/30 power unit-to-ESS ratio or a “70/30 ratio.” In other words, the output capacity and/or limits of the power sources interconnected via bus4to propulsion loads, namely ESS34and power units6, may not be the same and each may be a proportion of the total output power available to meet power demand. In some examples of sequential power management method600, a power share request may specify a portion of the ESS output capacity, e.g., an ESS output limit, below which the system may use the ESS to meet an increasing and/or changing power demand, and above which the system prioritizes other power sources. In the examples shown inFIGS.4-6, the output capacity of the ESS is 30% of the total available power, and a 67% power share request results in an ESS output limit of 20% of the total available power, e.g., 67% of the 30% ESS output capacity.

FIG.5is an example of a plurality of plots500illustrating example power output as a function of power demand curves502-522for a plurality of power share requests, in accordance with one or more techniques of this disclosure. The example shown illustrates various ESS curves and power unit curves for various power share requests. Similar to plot400, plot500illustrates the power output versus power demand curves502-522for a 70/30 power unit-to-ESS ratio. Total power curve502is the sum of corresponding power unit curves and ESS curves, e.g., the sum of power unit curve504and ESS curve514, the sum of power unit curve506and ESS curve516, etc.

FIG.6is a flowchart of an example method600of sequential power management in a hybrid propulsion system, in accordance with one or more techniques of this disclosure. The example method600may be performed, for example, by controller36executing the steps of the method.

A power demand and/or a power share request may be received (602). For example, a user may provide input via a throttle, switch, etc., which may be converted to a power demand by system state manager302, motor demand manager304, source demand manager308, and/or controller36. In some examples, a power share request may be input by a user, or a power share request may originate from another system component that determines the power share request via a control algorithm or according to a schedule, or power share request may be determined by controller36via a control algorithm or according to a schedule. An ESS output limit may be determined based on the power share request.

Whether the power demand is less than or equal to the ESS output limit may be determined (604). If the power demand is less than or equal to the ESS output limit, ESS output may be adjusted and/or changed to meet the power demand (606). For example, controller36may cause ESS34to increase and/or decrease output to meet the power demand. In some examples, ESS output may displace power unit output. For example, power unit6A may be a voltage regulator of electrical bus4. As total required power increases, the voltage on electrical bus4may decrease and power unit6A, as voltage regulator, may increase output so as to increase the voltage on electrical bus4to a predetermined voltage or voltage range. Alternatively, as total required power decreases, the voltage on electrical bus4may increase and power unit6A, as voltage regulator, may decrease output so as to decrease the voltage on electrical bus4to a predetermined voltage or voltage range. At (606), ESS34output may be adjusted to displace the adjusted output of the voltage regulator, e.g., power unit6A. In some examples, ESS34may be a voltage regulator, and in other examples other components of the system may be a voltage regulator. For example, by utilizing droop control, any or all of ESS34, power unit6A, and electric machine14A may be voltage regulators concurrently.

In the example illustrated inFIG.4, the power share request of 67% results in an the ESS output limit that is 20% of the total available output power, as described above. In the example shown, ESS curve406increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from 0% up to and including 20% and is equal to and overlaps with total power output curve402within that range. Power unit curve404remains at 0% for a power demand from 0% up to and including 20%. In the example shown, the power share request of 67% for the sequential method600results in all of the power demand being sourced from ESS34for a power demand less than or equal to the ESS output limit of 20%.

FIG.5illustrates ESS and power unit curves for other power share request values. In the example illustrated inFIG.5, power unit curve508and ESS curve518correspond to a 33% power share request, resulting in an ESS output limit of 10% of the total output power based on the example 70/30 ratio. ESS curve518increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from 0% up to and including 10% and is equal to and overlaps with total power output curve502within that range. Power unit curve508remains at 0% for a power demand of 0% up to and including 10%. In the example shown, the power share request of 33% for the sequential method600results in all of the power demand being sourced from ESS34for a power demand less than or equal to the ESS output limit of 10%.

Power unit curve510and ESS curve520correspond to a 67% power share request, similar to the example illustrated inFIG.4above.

Power unit curve512and ESS curve522correspond to a 100% power share request, resulting in an ESS output limit of 30% of the total output power based on the example 70/30 ratio. ESS curve522increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from 0% up to and including 30% and is equal to and overlaps with total power output curve502within that range. Power unit curve512remains at 0% for a power demand from 0% up to and including 30%. In the example shown, the power share request of 100% for the sequential method600results in all of the power demand being sourced from ESS34for a power demand less than or equal to the ESS output limit of 30%.

Returning now toFIG.6, if the power demand is not less than or equal to ESS output limit at (604), whether the power demand is less than or equal to the sum of the ESS output limit and the power unit output limit may be determined (608). If the power demand is less than or equal to the sum of the ESS output limit and the power unit output limit, the power unit may increase and/or decrease power to meet the power demand (610). For example, controller36may cause power unit6A to increase and/or decrease output power to meet the power demand.

In the example illustrated inFIG.4, power unit curve404increases and/or decreases with a 1:1 correspondence to the power demand for a power demand greater than 20%. The power unit output limit is 70% of the total output power based on the example 70/30 ratio, and power unit curve404increases and/or decreases in 1:1 correspondence to the power demand up to and including a power demand of 90%, e.g., the sum of the ESS output limit and the power unit output limit. ESS curve406remains constant at 20% for a power demand greater than 20% up to and including 90%. In the example shown, the power share request of 67% for the sequential method600results in 20% of the power demand, e.g., the ESS output limit, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand that is less than or equal to the sum of the ESS output limit and the power unit output limit at (610).

In the examples illustrated inFIG.5, power unit curve506and ESS curve516correspond to a 0% power share request, resulting in an ESS output limit of 0% of the total output power. Power unit curve506increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 0% up to and including 70%, e.g., from greater than 0% to the sum of the ESS output limit and the power unit output limit. ESS curve516remains constant at 0% for a power demand from greater than 0% up to and including 70%. In the example shown, the power share request of 0% for the sequential method600results in 0% of the power demand, e.g., the ESS output limit, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand less than or equal to the sum of the ESS output limit and the power unit output limit at (610).

Power unit curve508and ESS curve518correspond to a 33% power share request, resulting in an ESS output limit of 10% of the total output power. Power unit curve508increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 10% up to and including 80%, e.g., from greater than 10% to the sum of the ESS output limit and the power unit output limit. ESS curve518remains constant at 10% for a power demand greater than 10% up to and including 80%. In the example shown, the power share request of 33% for the sequential method600results in 10% of the power demand, e.g., the ESS output limit, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand less than or equal to the sum of the ESS output limit and the power unit output limit at (610).

Power unit curve510and ESS curve520correspond to a 67% power share request, similar to the examples illustrated inFIG.4above.

Power unit curve512and ESS curve522correspond to a 100% power share request, resulting in an ESS output limit of 30% of the total output power. Power unit curve512increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 30% up to and including 100%. ESS curve522remains constant at 30% for a power demand from greater than 30% up to and including 100%. In the example shown, the power share request of 100% for the sequential method600results in 30% of the power demand, e.g., the ESS output limit, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand less than or equal to the sum of the ESS output limit and the power unit output limit at (610).

In some examples, power share request306may be negative. In the example shown inFIG.5, power unit curve504and ESS curve514illustrate a power share request of −33% resulting in an ESS output limit of −10% and corresponding to charging ESS34, for example, via drawing power from electrical bus4. Power unit6A increases output to meet the power demand, which includes ESS34charging on electrical bus4in the example shown, as illustrated by power unit curve504having a 10% total power output at 0% power demand and ESS curve514having a −10% output (10% power draw to charge).

Returning now toFIG.6, if the power demand is not less than or equal to the sum of the ESS output limit and the power unit output limit at (610), whether the power demand is less than or equal to the sum of the ESS output capacity and the power unit output limit (612). For example, the power share request and ESS output limit may be overridden to meet a power demand, such as a propulsion power demand.

If the power demand is less than or equal to the sum of the ESS output capacity and the power unit output limit at (612), ESS output may be increased and/or changed or decreased to meet the power demand (614). For example, controller36may override the power share request and ESS output limit and cause ESS34to increase and/or decreases output power to meet demand for a power demand less than or equal to the sum of the ESS output capacity and the power unit output limit.

In the example illustrated inFIG.4, ESS curve406increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 90% up to and including 100%. Power unit curve404remains constant at 70% for a power demand from greater than 90% up to and including 100%. In the example shown, the power share request of 67% for the sequential method600results in 70% of the power demand, e.g., the power unit output limit, being sourced from power unit6A and the rest of the power demand being sourced from ESS34for a the power demand is less than or equal to the sum of the ESS output capacity and the power unit output limit at (614).

In the examples illustrated inFIG.5, ESS curve516increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 70% up to and including 100%. Power unit curve506remains constant at 70% for a power demand from greater than 70% up to and including 100%. In the example shown, the power share request of 0% for the sequential method600results in 70% of the power demand, e.g., the power unit output limit, being sourced from power unit6A and the rest of the power demand being sourced from ESS34for a power demand is less than or equal to the sum of the ESS output capacity and the power unit output limit at (614).

ESS curve518increases and/or decreases with a 1:1 correspondence to the power demand for a power demand from greater than 80% up to and including 100%. Power unit curve508remains constant at 70% for a power demand from greater than 80% up to and including 100%. In the example shown, the power share request of 33% for the sequential method600results in 70% of the power demand, e.g., the power unit output limit, being sourced from power unit6A and the rest of the power demand being sourced from ESS34for a power demand is less than or equal to the sum of the ESS output capacity and the power unit output limit at (614).

Power unit curve510and ESS curve520correspond to a 67% power share request, similar to the examples illustrated inFIG.4above.

Returning now toFIG.6, if the power demand is not less than or equal to the sum of the ESS output capacity and the power unit output limit at (612), power unit output may be increased and/or decreased to meet the power demand (616). For example, the power unit output limit may be overridden to meet a power demand, such as a propulsion power demand. In some examples, the total available output power illustrated inFIGS.4-5is the total output power according to power unit and ESS limits and is less than the total possible power output. Total possible output power may be based on the peak power outputs of the power units and the output capacities of the ESS's.

Sequential power management method600may be used for increasing and/or decreasing power demands. For example, the power outputs of ESS34and power unit6A illustrated inFIGS.4-5may be valid for a power demand that is adjusted to increase and/or decrease.

FIGS.7-9illustrate an example continuous power management method900and are described concurrently with reference to each other below. Some of the example power share requests illustrated inFIGS.7-9are different from those ofFIGS.4-6for improved visibility in the plots and to better illustrate the differences between continuous power management method900and sequential power management method600.

FIG.7is an example plot700illustrating example power output as a function of power demand curves702-706for a power share request of 60%, in accordance with one or more techniques of this disclosure. In the example shown, total power curve702is the sum of power unit curve704and ESS curve706for a 70/30 power unit-to-ESS power ratio as described above with respect toFIG.4.

In some examples of continuous power management method900, a power share request may specify a ratio of the power demand to be sourced from a plurality of power sources, namely the ESS and the power unit, for power demands less than or equal to the output capacity of the ESS or the power unit output limit. In the examples shown inFIGS.7-9, the output capacity of the ESS is 30% of the total available power and the power unit output limit is 70%, per the 70/30 power unit-to-ESS power ratio of the examples. A 60% power share request results in a 60% of the power demand being sourced by the ESS and 40% of the power demand being sourced by the power unit for a power demand less than or equal to the ESS output capacity divided by the power sharing request in the examples ofFIGS.7-9. In other words, a power demand equal to the ESS output capacity divided by the power share request (as a decimal from 0 to 1, e.g., representing an output sharing percentage) is the power demand at which the ESS output capacity is reached. In the example ofFIG.7, the ESS output capacity is reached at 50%, e.g., 30%÷60%, or 0.3÷0.6.

FIG.8is an example of a plurality of plots800illustrating example power output as a function of power demand curves802-822for a plurality of power share requests, in accordance with one or more techniques of this disclosure. Similar to plot700, plot800illustrates the power output versus power demand curves802-822for a 70/30 power unit-to-ESS ratio. Total power curve802is the sum of corresponding power unit curves and ESS curves, e.g., the sum of power unit curve804and ESS curve814, the sum of power unit curve806and ESS curve816, etc. In some of the examples of plot800, certain power share request values result in the ESS reaching its output capacity to meet a power demand before the power unit output limit is reached, which is the situation described above with respect toFIG.7. In other examples of plot800, certain other power share request values result in the power unit reaching its output limit to meet a power demand before the ESS reaches its output capacity. The point at which the power unit reaches its output capacity is a power demand equal to the power limit output limit divided by 100% minus the power share request. In other words, a power demand equal to the power unit output limit divided by one minus the power share request (as a decimal from 0 to 1, e.g., representing an output sharing percentage) is the power demand at which the power unit output limit is reached. For example, for a power share request of 20% illustrated by ESS curve816and power unit curve806ofFIG.8, the power unit output limit is reached at 87.5%, e.g., 70%÷(100%-20%), or 0.7÷(1−0.2).

FIG.9is a flowchart of an example method900of continuous power management in a hybrid propulsion system, in accordance with one or more techniques of this disclosure. The example method900may be performed, for example, by controller36executing the steps of the method.

A power demand and/or a power share request may be received (902). For example, a user may provide input via a throttle, switch, etc., which may be converted to a power demand by system state manager302, motor demand manager304, source demand manager308, and/or controller36. In some examples, a power share request may be input by a user, or a power share request may originate from another system component that determines the power share request via a control algorithm or according to a schedule, or power share request may be determined by controller36via a control algorithm or according to a schedule.

Whether the power demand is less than or equal to the ESS output capacity divided by the power share request and less than the power unit output limit divided by one minus the power share request may be determined (904). To simplify the description herein, the ESS output capacity divided by the power share request will be referred to as the “ESS condition” for the continuous power management method900and the power unit output limit divided by one minus the power share request will be referred to as the “power unit condition” for the continuous power management method900. If the power demand is less than or equal to both the continuous power management method ESS and power unit conditions, both ESS output and power unit output may be increased, decreased, and/or changed or adjusted to meet the power demand (906). For example, controller36may cause both ESS34and power unit6A to increase and/or decrease output to meet the power demand. In some examples, ESS output may displace power unit output. For example, power unit6A may be a voltage regulator of electrical bus4. As total required power increases, the voltage on electrical bus4may decrease and power unit6A, as voltage regulator, may increase output so as to increase the voltage on electrical bus4to a predetermined voltage or voltage range. Alternatively, as total required power decreases, the voltage on electrical bus4may increase and power unit6A, as voltage regulator, may decrease output so as to decrease the voltage on electrical bus4to a predetermined voltage or voltage range. At (906), ESS34output may be increased and/or decreased to displace at least a portion of the increased and/or decreased output of the voltage regulator, e.g., power unit6A. In some examples, ESS34may be a voltage regulator, and in other examples other components of the system may be a voltage regulator. For example, by utilizing droop control, any or all of ESS34, power unit6A, and electric machine14A may be voltage regulators concurrently.

In the example illustrated inFIG.7, the power share request of 60% results in an ESS power output that is 60% of the power demand and a power unit output that is 40% of the power demand less than or equal to 50%, at which point the ESS condition is met and the ESS output has reached its 30% output capacity. In the example shown, the ESS curve706increases and/or decreases with a 0.6:1 correspondence to the power demand for a power demand of 0% to 50%. Power unit curve704increases and/or decreases with a 0.4:1 correspondence to the power demand for a power demand less than or equal to 50%.

FIG.8illustrates ESS and power unit curves for other power share request values. Power unit curve806and ESS curve816correspond to a 20% power share request resulting in an ESS power output that is 20% of the power demand and a power unit output that is 80% of the power demand for a power demand that is less than equal to 87.5%, at which point the power unit condition is met and the power unit has reached its 70% output limit. For a power share request of 20%, the power unit condition is less than the ESS condition. ESS curve816increases and/or decreases with a 0.2:1 correspondence to the power demand and power unit curve806increases and/or decreases with a 0.8:1 correspondence to the power demand for a power demand less than or equal to the power unit condition, e.g., 87.5%.

Power unit curve808and ESS curve818correspond to a 40% power share request, resulting in an ESS power output that is 40% of the power demand and a power unit output that is 60% of the power demand for a power demand that is less than or equal to 75%, at which point the ESS condition is met and the ESS has reached its 30% output capacity. For a power share request of 40%, the ESS condition is less than the power unit condition. ESS curve818increases and/or decreases with a 0.4:1 correspondence to the power demand and power unit curve808increases and/or decreases with a 0.6:1 correspondence to the power demand for a power demand less than or equal to the ESS condition, e.g., 75%.

Power unit curve810and ESS curve820correspond to a 60% power share request, similar to the example illustrated inFIG.7above.

Power unit curve812and ESS curve822correspond to an 80% power share request, resulting in an ESS power output that is 80% of the power demand and a power unit output that is 20% of the power demand for a power demand that is less than or equal to 37.5%, at which point the ESS condition is met and the ESS has reached its 30% output capacity. For a power share request of 80%, the ESS condition is less than the power unit condition. ESS curve822increases and/or decreases with a 0.8:1 correspondence to the power demand and power unit curve812increases and/or decreases with a 0.2:1 correspondence to the power demand for a power demand less than or equal to the ESS condition, e.g., 37.5%.

In some examples, power share request306may be negative, as described above with respect toFIG.5. Similarly, in the example shown inFIG.8, power unit curve804and ESS curve814illustrate a negative power share request resulting in the ESS drawing power from electrical bus4to charge. Power unit6A increases output to meet the power demand, which includes ESS34charging on electrical bus4in the example shown and as described above.

Returning now toFIG.9, if the power demand is not less than or equal to both the ESS condition and the power unit condition at (904), whether the power demand is greater than either of the ESS condition and power unit condition and less than the sum of the ESS output capacity and power unit output limit may be determined (908). If the power demand is greater than either of the ESS condition and power unit condition but less than or equal to the sum of the ESS capacity and power unit output limit (e.g., 100%), one or the other, but not both, of the ESS and the power unit may increase and/or decrease power to meet the power demand (910). For example, controller36may cause ESS34to increase and/or decrease output power to meet a power demand that is greater than the power unit condition but not greater than 100%. Alternatively, controller36may cause power unit6A to increase and/or decrease output power to meet a power demand that is greater than the ESS condition but not greater than 100%.

In the example illustrated inFIG.7, power unit curve704increases and/or decreases with a 1:1 correspondence to the power demand and ESS curve706remains constant at the ESS output capacity 30% for a power demand greater than the ESS condition, 50%, but less than the power unit condition, 175%. The power unit condition of 175% indicates that the power unit output limit would not otherwise be reached before the total power demand reaches 100% if the 60/40 ESS to power unit ratio were allowed to continue. In the example shown, the power share request of 60% for the continuous power management method900results in 30% of the power demand, e.g., the ESS output capacity, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand greater than the ESS condition and less than the power unit condition.

In the examples illustrated inFIG.8, ESS curve816increases and/or decreases with a 1:1 correspondence to the power demand and power unit curve806remains constant at the power unit output limit 70% for a power demand greater than the power unit condition, 87.5%, but less than the ESS condition, 150%, based on the 20% power share request. The ESS condition of 150% indicates that the ESS output capacity would not otherwise be reached before the total power demand reaches 100% if the 20/80 ESS to power unit ratio were allowed to continue. In the example shown, the power share request of 20% for the continuous power management method900results in 70% of the power demand, e.g., the power unit output limit, being sourced from power unit6A and the rest of the power demand being sourced from ESS34for a power demand greater than the power unit condition and less than the ESS condition.

Power unit curve808increases and/or decreases with a 1:1 correspondence to the power demand and ESS curve818remains constant at the ESS output capacity 30% for a power demand greater than the ESS condition, 75%, but less than the power unit condition, 117%, based on the 40% power share request. Similar to the example ofFIG.7, the power unit condition of 117% indicates that the power unit output limit would not otherwise be reached before the total power demand reaches 100% if the 40/60 ESS to power unit ratio were allowed to continue. In the example shown, the power share request of 40% for the continuous power management method900results in 30% of the power demand, e.g., the ESS output capacity, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand greater than the ESS condition and less than the power unit condition.

Power unit curve810and ESS curve820correspond to a 60% power share request, similar to the examples illustrated inFIG.7above.

Power unit curve812increases and/or decreases with a 1:1 correspondence to the power demand and ESS curve822remains constant at the ESS output capacity 30% for a power demand greater than the ESS condition, 37.5%, but less than the power unit condition, 350%, based on the 20% power share request. Similar to the example ofFIG.7, the power unit condition of 350% indicates that the power unit output limit would not otherwise be reached before the total power demand reaches 100% if the 40/60 ESS to power unit ratio were allowed to continue. In the example shown, the power share request of 40% for the continuous power management method900results in 30% of the power demand, e.g., the ESS output capacity, being sourced from ESS34and the rest of the power demand being sourced from power unit6A for a power demand greater than the ESS condition and less than the power unit condition.

Returning now toFIG.9, if the power demand is not less than or equal to the sum of the output capacity and the power unit output limit, e.g., 100%, power unit output may be increased and/or decreased to meet the power demand (914). For example, the power unit output limit may be overridden to meet a power demand, such as a propulsion power demand. In some examples, the total output power illustrated inFIGS.7-8is the total output power according to power unit and ESS limits. Total available output power may be based on the peak power outputs of the power units and the output capacities of the ESS's and may be greater than the total output power illustrated inFIGS.7-8.

Continuous power management method900may be used for increasing and/or decreasing power demands. For example, the power outputs of ESS34and power unit6A illustrated inFIGS.7-8may be valid for a power demand that is adjusted to increase and/or decrease.

FIGS.10-11illustrate an example scheduled power management method1100and are described concurrently with reference to each other below.

FIG.10is a plot illustrating an example plot1000illustrating example power output as a function of power demand curves1002-1006for a scheduled power share request, in accordance with one or more techniques of this disclosure. In the example shown, total power curve1002is the sum of power unit curve1004and ESS curve1006for a 70/30 power unit-to-ESS power ratio as described above with respect toFIG.4. In the example shown, low power demand is all electric, e.g., sourced only from ESS34. Mid-range power demand is increasingly sourced via power units6, and high-power demands are sourced almost all via power units6. For power demands higher than the output limits of the power units6, the ESS provides the power boost. For critical power demands greater than the power units6providing power at their respective output limits and the ESS's providing power at their respective output capacities, the power unit output limits may be overridden to provide extra power, for example, for critical propulsion demands.

FIG.11is a flowchart of an example method1100of scheduled power management in a hybrid propulsion system, in accordance with one or more techniques of this disclosure. The example method1100may be performed, for example, by controller36executing the steps of the method. In some examples of scheduled power management method1100, a power share request may directly specify ESS output as a function of power demand, with the power unit supplying the rest of the power demand. In other examples of scheduled power management method1100, the method1100may determine a power share request based on a received power demand and a predetermined schedule and may output the determined power share request and power demand as input to sequential power management method600and/or continuous power management method900. In some examples, a scheduled power management method may replace a user selecting a power share request value.

A power demand may be received or otherwise obtained (1102). As one example, a user may provide input via a throttle, switch, etc., which may be converted to a power demand by system state manager302and/or controller36.

Whether the power demand is less than or equal to a first power demand threshold may be determined (1104). If the power demand is less than or equal to the first power demand threshold, the power share request may be set to 100% and ESS output may be increased, decreased and/or changed to meet the power demand. For example, controller36may cause ESS34to increase and/or decrease output to meet the power demand. In some examples, ESS output may displace power unit output, as described above with respect toFIG.6.

In the example illustrated inFIG.10, the scheduled power share request of 100% results in all of the power demand being sourced from the ESS for a power demand that is less than or equal to the first threshold T1. In the example shown, first threshold T1is a power demand of 10% of the total available power. ESS curve406increases and/or decreases with a 1:1 correspondence to the power demand and power unit curve404remains at 0% for a power demand from 0% to less than or equal to 10%, e.g., the first threshold.

If the power demand is greater than the first power demand threshold at (1104), whether the power demand is less than or equal to a second power demand threshold may be determined (1106). If the power demand is less than or equal to the second power demand threshold, the power share request may be determined such that the ESS output reduces from its power output level at the first threshold to 0% at the second threshold.

In the example illustrated inFIG.10, ESS curve1006decreases linearly from an ESS output level of 10% at a power demand of 10% to a ESS output level of 0% at a power demand of the second threshold T1, e.g., 50% in the example shown. The rest of the power demand is source from the power unit, which correspondingly increases and/or decreases linearly from 0% at a power demand of T1to the sourcing all of the power demand at T2, e.g., 50% in the example shown. In some examples, the ESS output level may decrease at a rate other than linearly, e.g., exponentially, according to predetermined schedule, according to any other function, such as polynomial, and the like.

If the power demand is greater than the second power demand threshold at (1106), whether the power demand is less than or equal to the power unit output limit may be determined (1108). If the power demand is less than or equal to the power unit output limit, the power share request may be set to 0% resulting in all of the power demand being supplied by the power unit.

In the example illustrated inFIG.10, ESS curve1006remains at 0% and power unit curve1004increases and/or decreases with a 1:1 correspondence to the power demand for a power demand greater than the second threshold T2and less than or equal to the power unit output limit, e.g., 70% in the example shown per the 70/30 ratio of the example.

If the power demand is greater than the power unit output limit at (1108), whether the power demand is less than or equal to the sum of the power unit output limit and the ESS output capacity may be determined (1110). If the power demand is less than or equal to the sum of the power unit output limit and the ESS output capacity, the power share request may be set to 100% and/or the ESS output may be increased and/or decreased to meet the power demand.

In the example illustrated inFIG.10, ESS curve1006increases and/or decreases with a 1:1 correspondence to the power demand and power unit curve1004remains at 70% for a power demand greater than the power unit output limit and less than or equal to the sum of the power unit output limit and the ESS output capacity, e.g., 100% of the total available power.

If the power demand is greater than the sum of the power unit output limit and the ESS output capacity at (1110), the power unit output may be increased and/or decreased to meet the power demand (1112), as described above with respect toFIGS.6and9. For example, the power unit output limit may be overridden to meet a power demand, such as a propulsion power demand. In some examples, the total available output power illustrated inFIG.10is the total output power according to power unit and ESS limits and is less than the total possible power output. Total possible output power may be based on the peak power outputs of the power units and the output capacities of the ESS's.

Scheduled power management method1100may be used for increasing and/or decreasing power demands. For example, the power outputs of ESS34and power unit6A illustrated inFIG.10may be valid for a power demand that is adjusted to increase and/or decrease. In other examples, the ESS curve1006and power unit curve1004of plot1000may follow different paths for decreasing power demands, e.g., plot1000may have hysteresis.

In other examples, power schedule management method1100may use fewer or more thresholds, and may determine a power share request, ESS output, and/or power unit output based on any of the power demand, one or more power demand thresholds, one or more ESS output capacities, one or more ESS output limits, one or more power unit output limits and peak outputs, ESS and/or power unit faults and/or fault conditions, environmental conditions, and the like.

In some examples, other power schedule methods may determine the sourcing distribution among one or more ESS's and one or more power units for any power demand in any manner. For example, power schedule management method may specify the amount of power to be sourced from each individual power unit6and ESS for any power demand.

FIG.12is a plot illustrating example degraded power management curves, in accordance with one or more techniques of this disclosure. The example shown illustrates power demand curves402-406for a power share request of 67% of an example sequential power management method, such as method600, in comparison with the equivalent power demand curves1202-1206for a power share request of 67% of the example sequential power management method for a degraded ESS. For example, ESS34may be almost out of charge and has been limited to only 67% of its full capability/capacity to prevent damaging excess discharge.

In the example shown, total power curve1202is the sum of power unit curve1204and ESS curve1206. The example shown is illustrated for a 70/20 ratio, e.g., the output power of the ESS is degraded by 10% and the ESS is only able to reach 20% of the total output power rather than 30%, as described above with respect toFIG.4. In the examples shown, the total power curve1202shows a maximum output of 90% for power demands greater than 90% as a consequence of the degraded ESS. In the example shown, the degraded ESS curve1206is shifted down 10% relative to ESS curve406. As such, the power unit curve1204is shifted “left” relative to power unit curve404, e.g., the power unit supplies output power for lower power demands, e.g., greater than 10%, in order to meet the power demand in conjunction with a degraded ESS. As described above, in some examples for power demands greater than 100%, or 90% in the current example, power unit6A may override its output limits to provide output power up to its output power capacity.

FIG.13is a plot illustrating example degraded power management curves, in accordance with one or more techniques of this disclosure. The example shown illustrates power demand curves402-406for a power share request of 67% of an example sequential power management method, such as method600, in comparison with the equivalent power demand curves1302-1306for a power share request of 67% of the example sequential power management method for a degraded power unit. For example, power unit may be operating at an elevated temperature and may have less power available, e.g., the power unit may have only 86% of its full capability/capacity.

In the example shown, total power curve1302is the sum of power unit curve1304and ESS curve1306. The example shown is illustrated for a 60/30 ratio, e.g., the output power of the power unit is degraded by 10% and the power unit is only able to reach 60% of the total output power rather than 70%, as described above with respect toFIG.4. In the examples shown, the total power curve1302shows a maximum output of 90% for power demands greater than 90% as a consequence of the degraded power unit. In the example shown, the degraded power unit curve1304is shifted down 10% relative to power unit curve404. As such, the ESS curve1306is shifted “left” relative to ESS curve406, e.g., the ESS supplies output power for lower power demands beyond the output limit of the power unit, e.g., greater than 80%, in order to meet the power demand in conjunction with a degraded power unit. In some examples, the ESS may be the be required to change modes when the power unit is fully degraded/disabled, such as from current regulation to voltage regulation.

FIG.14is a plot illustrating example disabled power management curves, in accordance with one or more techniques of this disclosure. The example shown illustrates power demand curves402-406for a power share request of 67% of an example sequential power management method, such as method600, in comparison with the equivalent power demand curves1402-1406for a power share request of 67% of the example sequential power management method for a disabled ESS. For example, ESS34may be non-functional, fully out of charge, and/or otherwise disabled.

In the example shown, total power curve1402is the sum of power unit curve1404and ESS curve1406, e.g., which is at 0% output for any power demand because it is disabled. The example shown is illustrated for a 70/0 ratio, e.g., the output power of the ESS is disabled by 100% and the ESS is only able to reach 0% of the total output power rather than 30%, as described above with respect toFIG.4. In the examples shown, the total power curve1402shows a maximum output of 70% for power demands greater than 70% as a consequence of the disabled ESS. In the example shown, the disabled ESS curve1406is shifted down to 0% output. As such, the power unit curve1404is shifted “left” relative to power unit curve404, e.g., the power unit supplies output power for lower power demands, e.g., greater than 0%, in order to meet the power demand in conjunction with a disabled ESS. As described above, in some examples for power demands greater than 100%, or 70% in the current example, power unit6A may override its output limits to provide output power up to its output power capacity.

FIG.15is a plot illustrating example disabled power management curves, in accordance with one or more techniques of this disclosure. The example shown illustrates power demand curves402-406for a power share request of 67% of an example sequential power management method, such as method600, in comparison with the equivalent power demand curves1502-1506for a power share request of 67% of the example sequential power management method for a disabled power unit which may not output any power.

In the example shown, total power curve1502is the sum of power unit curve1504, e.g., which is at 0% output for any power demand because it is disabled, and ESS curve1506. The example shown is illustrated for a 0/30 ratio, e.g., the output power of the power unit is disabled by 100% and the power unit is only able to reach 0% of the total output power rather than 70%, as described above with respect toFIG.4. In the examples shown, the total power curve1502shows a maximum output of 30% for power demands greater than 30% as a consequence of the disabled power unit. In the example shown, the disabled power unit curve1504is shifted down to 0% output. As such, the ESS curve1506is shifted “left” relative to ESS curve406, e.g., the ESS supplies output power for lower power demands in order to meet the power demand in conjunction with a disabled power unit. In some examples, the ESS may be the be required to change modes because the power unit is fully disabled, such as from current regulation to voltage regulation.

In some examples, controller36may determine that an ESS or a power unit, e.g., ESS34and/or power unit6A, are degraded and/or disabled. For example, controller36may receive information from ESS34and/or power unit6A such as feedback relating to electrical current and environmental conditions of ESS34and power unit6A such as temperatures and pressures. Controller36may determine the amount of degradation of ESS34and power unit6A. In some examples, controller36may determine a predetermined ESS output limit based on the power share request and the determined degradation of one or more ESS and power unit.

In some examples, both the ESS and the power unit may be degraded/disabled.

The following examples may illustrate one or more aspects of the disclosure:

Example 1. A method of managing power in a hybrid propulsion system, the method comprising: receiving, by one or more processors, a power demand that specifies an amount of power to be used to propel a vehicle that includes an electrical energy storage system (ESS) and one or more electrical generators, wherein the one or more electrical generators are configured to convert mechanical energy to electrical energy; determining, based on the power demand and a predetermined ESS output limit, a first amount of power to be sourced from the ESS and a second amount of power to be sourced from the one or more generators; and causing, by the one or more processors, the ESS to output the first amount of power onto a direct current (DC) electrical distribution bus and the one or more generators to output the second amount of power onto the DC electrical distribution bus.

Example 2. The method of example 1, wherein determining the first amount of power and the second amount of power comprises determining that the second amount of power is zero in response to determining that the amount of power specified by the power demand is less than or equal to the predetermined ESS output limit.

Example 3. The method of any one of examples 1-2, wherein determining the first amount of power and the second amount of power comprises determining that the first amount of power is the predetermined ESS output limit in response to determining that the amount of power specified by the power demand is greater than the predetermined ESS output limit and is less than or equal to a predetermined output limit of the one or more electrical generators.

Example 4. The method of any one of examples 1-3, wherein determining the first amount of power and the second amount of power comprises determining that the first amount of power is greater than the predetermined ESS output limit in response to determining that the amount of power specified by the power demand is greater than the predetermined output limit of the one or more electrical generators.

Example 5. The method of any one of examples 1-4, wherein determining the first amount of power and the second amount of power comprises determining that the first amount of power is a maximum available ESS output capability and that the second amount of power is greater than the predetermined output limit of the one or more electrical generators in response to determining that the amount of power specified by power demand is greater than the sum of the predetermined ESS output limit and the predetermined output limit of the one or more electrical generators.

Example 6. The method of any one of examples 1-5, wherein determining the first amount of power and the second amount of power comprises determining that the first amount of power is a pre-determined portion of the amount of power to be used to propel the vehicle and that the second amount of power is the difference between the amount of power to be used to propel the vehicle and the first amount of power for a power demand that is less than the predetermined ESS output limit.

Example 7. The method of any one of examples 1-6, further comprising determining the predetermined ESS output limit based on at least one of a user input and a control algorithm.

Example 8. The method of example 7, wherein the control algorithm comprises at least one of a power schedule and a mission plan.

Example 9. The method of example 8, wherein determining the predetermined ESS output limit based on the power schedule comprises one or more of: setting the predetermined ESS output limit to the ESS output capability for a power demand less than a first threshold; setting the predetermined ESS output limit between the ESS output capability and zero inversely proportional to the power demand for a power demand between the first threshold and a second threshold greater than the first threshold; setting the predetermined ESS output limit to zero for a power demand greater than the second threshold; and setting the predetermined ESS output limit to the ESS output capability for a power demand greater than both the second threshold and an output capability of the one or more generators.

Example 10. The method of any one of examples 1-9, further comprising determining the predetermined ESS output limit based on at least one of an ESS fault condition, an environmental condition, a change of an ESS output capability, and a total vehicle power available.

Example 11. The method of any one of example 1-10, further comprising determining the predetermined ESS output limit based on at least one of a degraded ESS and a degraded electrical generator.

Example 12. The method of any one of examples 1-11, wherein the one or more electrical generators regulate a voltage of the DC electrical distribution bus.

Example 13. A system comprising: an electrical energy storage system (ESS) configured to output electrical power onto a direct current (DC) electrical distribution bus; one or more electrical generators configured to output electrical power onto the DC electrical distribution bus, wherein the one or more electrical generators are configured to convert mechanical energy into electrical energy; one or more electrical propulsion units configured to propel a vehicle using electrical power received via the DC electrical distribution bus; and one or more processors configured to: receive a power demand that specifies an amount of power to be used to propel the vehicle; determine, based on the power demand and a predetermined ESS output limit, a first amount of power to be sourced from the ESS and a second amount of power to be sourced from the one or more generators; and cause the ESS to output the first amount of power onto the DC electrical distribution bus and cause the one or more electrical generators to output the second amount of power onto the DC electrical distribution bus.

Example 14. The system of example 13, wherein the one or more processors are further configured to determine that the second amount of power is zero based on a determination that the power demand is less than or equal to the predetermined ESS output limit.

Example 15. The system of any one of examples 13-14, wherein the one or more processors are further configured to determine that the first amount of power is predetermined ESS output limit based on a determination that the power demand is greater than the predetermined ESS output limit and is less than or equal to a predetermined output limit of the one or more electrical generators.

Example 16. The system of any one of examples 13-15, wherein the one or more processors are further configured to determine that the first amount of power is greater than the predetermined ESS output limit based on a determination that the power demand is greater than the predetermined output limit of the one or more electrical generators.

Example 17. The system of any one of examples 13-16, wherein the one or more processors are further configured to determine the predetermined ESS output limit based on at least one of an ESS fault condition, an environmental condition, a change of an ESS output capability, and a total vehicle power available.

Example 18. The system of any one of examples 13-17, wherein the one or more processors are further configured to determine the predetermined ESS output limit based on at least one of a degraded ESS and a degraded electrical generator.

Example 19. The system of any one of examples 13-18, wherein the one or more processors are further configured to determine the predetermined ESS output limit based on at least one of a user input and a control algorithm.

Example 120. The system of any one of examples 13-19, wherein the control algorithm comprises at least one of a power schedule and a mission plan.

Various examples have been described. These and other examples are within the scope of the following claims.