Abstract: Methods and systems for protection/disconnect of airborne high-power/energy high-voltage modular multi-string battery packs (such as battery packs for airborne electric propulsion systems). The methods and systems are based on a dissimilar/redundant distributed battery pack protection architecture and use a smart mid-point battery disconnect in conjunction with centralized battery management system. The resulting battery disconnect/protection system is configured to detect bus faults, load faults and string faults and then take appropriate action to isolate the detected fault. For example, in response to a short circuit in one battery string, the faulty battery string may be disconnected from the positive and negative busbars while the remaining battery strings continue to provide power.

Abstract: Methods and apparatus for detecting and characterizing arc faults in an aerospace electric propulsion system and then coordinating the operation of various elements of the protection system to execute a fault-clearing sequence. In a current-based method, the arc is detected and characterized based on differential readouts from current sensors. The difference between currents measured at two ends of a protection zone are compared to a difference threshold. In a power-based method, the arc is detected and characterized based on differential readouts from voltage and current sensors. The differential voltage and current readouts are used to compute the respective powers at two ends of a protection zone. The difference between the respective powers is integrated over a period of time and then the integrated difference is compared to a difference threshold. A differential protection trip mode is invoked when the difference threshold is exceeded.

Abstract: An electric propulsion unit comprising a housing, an AC motor, a beta rod, a propeller, a governor, an inverter, and a controller. The AC motor is disposed within the housing and includes bearings supported inside the housing, a hollow motor shaft rotatably coupled to the housing by the bearings, a stator which is supported by the housing, and a rotor which is mounted to the hollow motor shaft. The beta rod is axially translatable inside the hollow motor shaft. The propeller is mechanically coupled to the hollow motor shaft. The propeller includes propeller blades having an adjustable pitch angle which depends on an axial position of the beta rod. The governor is configured to adjust a pitch angle of the propeller blades by actuating axial translation of the beta rod. The controller is disposed inside the housing and configured to control the pitch angle of the propeller blades.

Abstract: An electrical system for an aircraft includes an AC electric power source electrically connected to a rotary electric motor via a plurality of AC contactors. An AC/DC inverter is electrically connected to the rotary electric motor, a DC power bus is electrically connected to the AC/DC inverter, and a plurality of sensors are arranged to monitor electric currents between the AC electric power source and the rotary electric motor. A first controller is arranged to control the AC/DC inverter; and a second controller is arranged to monitor the sensors and are operatively connected to the AC contactors. The second controller is operable to monitor, via the sensors, the electric currents between the AC electric power source and the rotary electric motor, and detect a fault based upon the electric currents, and deactivate the AC contactors in response to the fault.

Abstract: A discrete signal interlock system for activating an electric machine in an aircraft includes a first controller, a second controller, and a power source coupled via a single wiring harness bundle to a motor controller that is operatively connected to the electric machine. The motor controller includes a first circuit that is electrically coupled to a driver enabler of the motor controller, and a second circuit that is electrically coupled to a driver of the motor controller. The single wiring harness bundle encloses a first signal cable electrically coupling the first controller to the first circuit, a second signal cable electrically coupling the second controller to the second circuit, a first power cable electrically coupled to the first circuit, and a second power cable electrically coupled to the second circuit. Activation of the motor controller requires activation of the driver in concert with activation of the driver enabler.

Abstract: An electric drive system including an impedance balancing noise filtering circuit is disclosed. The electric drive system includes a direct current (DC) power source configured to output DC power to an output port and an inverter configured to convert the DC power output by the DC power source into alternating current (AC) power that is provided to an input port of an AC load. The impedance balancing noise filtering circuit includes an impedance bridge electrically intermediate the output port of the DC power source and the input port of the AC load. The impedance balancing noise filtering circuit includes different sets of passive components that are positioned on both the DC-side and the AC-side of the inverter. These sets of passive components are configured to facilitate impedance balancing that reduces common-mode (CM) electromagnetic interference (EMI) emission at the output port of the DC power source.

Abstract: Methods and apparatus for detecting and characterizing arc faults in an aerospace electric propulsion system and then coordinating the operation of various elements of the protection system to execute a fault-clearing sequence. In a current-based method, the arc is detected and characterized based on differential readouts from current sensors. The difference between currents measured at two ends of a protection zone are compared to a difference threshold. In a power-based method, the arc is detected and characterized based on differential readouts from voltage and current sensors. The differential voltage and current readouts are used to compute the respective powers at two ends of a protection zone. The difference between the respective powers is integrated over a period of time and then the integrated difference is compared to a difference threshold. A differential protection trip mode is invoked when the difference threshold is exceeded.

Abstract: A system including a power modulation device and an active voltage balancing system is provided. The power modulation device includes first and second semiconductor switches in series. The active voltage balancing system includes a differential voltage logic configured to detect a voltage difference between the first and second semiconductor switches and edge capture logic configured to detect a time difference between when the first and second semiconductor switches are switched. The active voltage balancing system further includes a micro-controller configured to output first and second gate drive signals to drive the first and second semiconductor switches. The micro-controller is configured to tune the first and second gate drive signals based on the voltage difference to compensate for voltage imbalance and the time difference to compensate for drive signal asymmetry to actively balance a voltage between the first and second semiconductor switches.

Abstract: A system and method for providing power to a vehicle is disclosed. The system can include a plurality of parallel module converter modules (“modules”) each capable of supplying a predetermined electrical load. The plurality of parallel module converter modules can be networked to form a parallel module converter (“converter”) for prioritizing and allocating each electrical load to one or more parallel module converter modules. Each module can include an internal protection controller and a logic controller. The individual modules can provide power to various loads in the vehicle either alone, or in concert with other modules. The system can enable fewer power controllers to be used, saving weight and time. The controllers in the system can also be utilized at a higher level reducing unnecessary redundancy.

Abstract: Methods and systems for charging a battery string while protecting against overcharging. One system includes: a pair of disconnect devices; a power distribution bus which is electrically connected to a battery string via the disconnect devices; a battery charger connected to supply battery power to the power distribution bus for charging the battery string; a module monitoring unit configured to sense individual battery cell voltages during charging; a first processor configured to activate one disconnect device to open when the sensed individual battery cell voltages indicate overcharging; a plurality of sensors connected to sense a full-string voltage measured across the battery string and first and second half-string voltages measured across first and second half-strings of the battery string; and a second processor connected to receive sensor data during charging.

Abstract: An electric drive system including an impedance balancing noise filtering circuit is disclosed. The electric drive system includes a direct current (DC) power source configured to output DC power to an output port and an inverter configured to convert the DC power output by the DC power source into alternating current (AC) power that is provided to an input port of an AC load. The impedance balancing noise filtering circuit includes an impedance bridge electrically intermediate the output port of the DC power source and the input port of the AC load. The impedance balancing noise filtering circuit includes different sets of passive components that are positioned on both the DC-side and the AC-side of the inverter. These sets of passive components are configured to facilitate impedance balancing that reduces common-mode (CM) electromagnetic interference (EMI) emission at the output port of the DC power source.

Abstract: A system including a power modulation device and an active voltage balancing system is provided. The power modulation device includes first and second semiconductor switches in series. The active voltage balancing system includes a differential voltage logic configured to detect a voltage difference between the first and second semiconductor switches and edge capture logic configured to detect a time difference between when the first and second semiconductor switches are switched. The active voltage balancing system further includes a micro-controller configured to output first and second gate drive signals to drive the first and second semiconductor switches. The micro-controller is configured to tune the first and second gate drive signals based on the voltage difference to compensate for voltage imbalance and the time difference to compensate for drive signal asymmetry to actively balance a voltage between the first and second semiconductor switches.

Abstract: An electric propulsion unit comprising a housing, an AC motor, a beta rod, a propeller, a governor, an inverter, and a controller. The AC motor is disposed within the housing and includes a plurality of bearings supported inside the housing, a hollow motor shaft rotatably coupled to the housing by the plurality of bearings, a stator which is supported by the housing, and a rotor which is mounted to the hollow motor shaft. The beta rod is axially translatable inside the hollow motor shaft. The propeller is mechanically coupled to the hollow motor shaft. The propeller includes propeller blades having an adjustable pitch angle which depends on an axial position of the beta rod. The governor is configured to adjust a pitch angle of the propeller blades by actuating axial translation of the beta rod. The inverter is disposed within the housing and connected to receive DC power for conversion into AC power.

Abstract: Methods and systems for protection/disconnect of airborne high-power/energy high-voltage modular multi-string battery packs (such as battery packs for airborne electric propulsion systems). The methods and systems are based on a dissimilar/redundant distributed battery pack protection architecture and use a smart mid-point battery disconnect in conjunction with centralized battery management system. The resulting battery disconnect/protection system is configured to detect bus faults, load faults and string faults and then take appropriate action to isolate the detected fault. For example, in response to a short circuit in one battery string, the faulty battery string may be disconnected from the positive and negative busbars while the remaining battery strings continue to provide power.

Abstract: A method for protecting an electric propulsion system in response to occurrence of a fault. The method includes the step of activating short circuits in power switches of inverters in a motor controller to redirect current regenerated by a motor which is electrically coupled to the motor controller and mechanically coupled to a propeller. The method further includes feathering the propeller while the motor is regenerating current. The protection logic is designed to address different types of faults, including faults in the high-voltage direct-current bus, faults in the motor controller, and faults in the motor.

Abstract: Systems and methods for current ripple reduction for a direct current (DC) source powering an alternating current (AC) load. In accordance with one embodiment, the system and method involve interleaved operation of a 3×3-phase AC motor having multiple groups of windings. In accordance with another embodiment, the system and method involve interleaved operation of multiple co-shafted 3-phase AC motors. In accordance with a further embodiment, the system and method involve interleaved operation multiple 3-phase AC motors (not co-shafted) of the same level of power. The interleaved operation entails interleaved switching inside a set of inverters which are connected in parallel between a DC bus and the windings of the AC motor (motors).

Abstract: A fault-tolerant power system architecture for aircraft electric propulsion. The fault-tolerant systems continue to operate in the event of the failure of (or one or more faults within) some component. The fault-tolerant design enables the system to continue its intended operation, possibly at a reduced level, rather than failing completely, when some part of the system fails. When a turn-to-turn fault in an AC motor is detected, a motor controller will short three top or three bottom switches in the inverter together (effectively shorting the associated stator windings) to divert fault current from the motor windings to the motor controller, where cooling is available. Also, when a fault in or at the input to a motor controller is detected, the motor controller cuts off power to the motor by issuing a command that causes an upstream contactor with high-voltage DC bus input to open.

Abstract: Systems and methods for current ripple reduction for a direct current (DC) source powering an alternating current (AC) load. In accordance with one embodiment, the system and method involve interleaved operation of a 3×3-phase AC motor having multiple groups of windings. In accordance with another embodiment, the system and method involve interleaved operation of multiple co-shafted 3-phase AC motors. In accordance with a further embodiment, the system and method involve interleaved operation multiple 3-phase AC motors (not co-shafted) of the same level of power. The interleaved operation entails interleaved switching inside a set of inverters which are connected in parallel between a DC bus and the windings of the AC motor (motors).

Abstract: A method for managing power in an airplane. Power quality data and load management data are collected from airplane systems in the airplane at a variable sampling rate using data collectors assigned to the airplane systems in which the variable sampling rate increases in response to a selected trigger event. The power quality data and the load management data are received by a power monitor from the data collectors during phases of flight for the airplane. A group of load management operations for the airplane systems are performed by a load manager in the airplane during operation of the airplane. The group of load management operations is performed using the power quality data and the load management data received from the data collectors during the phases of flight for the airplane.

Abstract: An electrical power system for regenerative loads may include a DC bus and an electrical actuator load, where back-driving the electrical actuator load generates regenerative electrical energy, and where the electrical actuator load is configured to transmit the regenerative electrical energy to the DC bus. The system may also include at least one additional load, where at least a portion of the regenerative electrical energy is transmitted to the at least one additional load.