Abstract: Magnetically-assisted mechanical gear systems and other power transmission systems, and related methods of operation and assembly, are disclosed herein. In an example embodiment, such a system includes a driving gear, a driven gear, and a first magnetomotive force (MMF) source that generates a magnetic flux. A first portion of the flux is communicated between at least one driving gear teeth and at least one driven gear teeth so that one or more magnetic forces are exerted between the gears. When the first rotational movement of the driving gear alternates from being in the first rotational direction to being in a third rotational direction opposite the first rotational direction, then the driven gear is driven by the one or more magnetic forces so that the second rotational movement also alternates, and a first amount of backlash movement between the driving and driven gears is avoided or reduced.

Abstract: A method of operating a power conversion system including converting variable frequency AC voltage to constant frequency AC voltage by a power converter, setting a first peak current reset threshold above operating currents previously observed during steady state short circuit current regulation in by a controller of the power converter, setting a second peak current reset threshold at a current lower than the previously observed steady state short-circuit regulation point observed during previous operation during steady state short circuit current regulation by the controllers of the power converter, resetting inverter converter AC output regulating voltage to 0 volts, and ramping AC output regulating voltage back up into steady-state operation when the second a peak current reset threshold is exceeded.

Abstract: A method of operating a power conversion system including converting variable frequency AC voltage to constant frequency AC voltage by a power converter, setting a first peak current reset threshold above operating currents previously observed during steady state short circuit current regulation in by a controller of the power converter, setting a second peak current reset threshold at a current lower than the previously observed steady state short-circuit regulation point observed during previous operation during steady state short circuit current regulation by the controllers of the power converter, resetting inverter converter AC output regulating voltage to 0 volts, and ramping AC output regulating voltage back up into steady-state operation when the second a peak current reset threshold is exceeded.

Abstract: A converter implementing a dual-reference three-level pulse width modulation (PWM) technique for constraining a midpoint duty cycle is provided. The converter includes a phase leg that includes upper, mid-upper, mid-lower, and lower switches. The upper, mid-upper, mid-lower, and lower switches are connected in series between direct current (DC) positive and negative leads, with an alternating current (AC) output lead connected at a junction of the mid-upper and mid-lower switches. The phase leg includes a first clamping diode connected to the junction of the switch and mid-upper switches and connected to a DC midpoint lead and a second clamping diode connected between the DC midpoint lead and connected to the junction of the mid-lower and lower switches. The converter is electrically coupled to and operatively associated with a controller to receive control signals to drive the converter to constrain the midpoint duty cycle between the DC midpoint and AC output leads.

Abstract: Embodiments of the invention provide for a system, method, and controller for operating a harmonic regulator with loop delay compensation. Some embodiments include receiving, at a controller, voltage feedback from a power system, and applying a harmonic regulator to each distortion frequency to be compensated. Embodiments also include applying a predetermined delay to an output of the harmonic regulator, scaling the delayed output and adding it to a power source voltage reference waveform, and providing condition power to a load, using the conditioned power source voltage reference waveform.

Abstract: A method of controlling an inverter includes generating a neutral-phase reference waveform, generating a neutral-phase midpoint compensation waveform using the neutral-phase reference waveform, and generating a neutral-phase compensated duty cycle waveform using the neutral-phase midpoint compensation waveform. Neutral-phase switch command signals are generated for switches of a neutral-phase of the inverter using the neutral-phase compensated duty cycle waveform. Inverters and computer program products are also described.

Abstract: A system and method for controlling a DC midpoint terminal voltage of a three level inverter is provided. The method includes receiving an input power signal at a three level motor controller system that includes a three level inverter, measuring, using a current sensor in the three level motor controller system, a DC current of the input power signal before the input power signal is provided to the three level inverter, and adjusting a zero-sequence inverter output voltage to adjust a midpoint voltage at the DC midpoint based on the measured DC current.

Abstract: A system and method for controlling a DC midpoint terminal voltage of a three level inverter is provided. The method includes receiving an input power signal at a three level motor controller system that includes a three level inverter, measuring, using a current sensor in the three level motor controller system, a DC current of the input power signal before the input power signal is provided to the three level inverter, and adjusting a zero-sequence inverter output voltage to adjust a midpoint voltage at the DC midpoint based on the measured DC current.

Abstract: A parallel semiconductor switching system includes an input filter circuit, a plurality of switching circuits, and a current-sharing filter inductor. The switching circuits receive the filtered voltage generated by the input filter circuit, and each switching circuit outputs a respective current. The current-sharing filter inductor includes a plurality of windings. Each winding has a winding input and a winding output. The winding input of each winding is connected to a switching output of a respective switching circuit, and the winding output of each winding is connected to one another to form a common node. The node common node is connected directly to a load such that the current-sharing filter inductor shares each current output from the plurality of switching circuits so as to deliver a combined current to the load.

Abstract: A system including a motor loss reducing controller system utilizing input band-shifting, an integral control architecture and inverse band-shifting is disclosed. The motor loss reducing controller system may provide correction of harmonic currents flowing to a PM motor from a motor controller. The compensation is added to the PWM voltage command signals. Within a compensator, d-axis and q-axis current feedback signals are frequency shifted down by n times the fundamental frequency. This converts the initial motor stationary harmonic currents into DC values. The frequency shifting is completed by multiplying the feedback signal by sine and cosine carrier signals of the shifted frequency. An integral controller may cancel any component of error at a desired DC value. An inverse frequency-shift transformation is applied to the output of the I controller in order to shift the command output signal back to the original reference frame.

Abstract: A system including a motor loss reducing controller system utilizing input band-shifting, an integral control architecture and inverse band-shifting is disclosed. The motor loss reducing controller system may provide correction of harmonic currents flowing to a PM motor from a motor controller. The compensation is added to the PWM voltage command signals. Within a compensator, d-axis and q-axis current feedback signals are frequency shifted down by n times the fundamental frequency. This converts the initial motor stationary harmonic currents into DC values. The frequency shifting is completed by multiplying the feedback signal by sine and cosine carrier signals of the shifted frequency. An integral controller may cancel any component of error at a desired DC value. An inverse frequency-shift transformation is applied to the output of the I controller in order to shift the command output signal back to the original reference frame.

Abstract: A multi-level power converter system includes a multi-level power converter configured to synthesize at least three direct current (DC) voltages into an alternating current (AC) output voltage, and includes a plurality of transistors. A controller generates pulse-width modulation (PWM) signals used to control a state of the plurality of transistors of the multi-level converter by comparing first and second carrier signals to a reference signals, wherein a period of the first and second carrier signals is randomly varied from a nominal period.

Abstract: A universal AC to DC converter may be configured to convert alternating current (AC) to direct current (DC), such as for use in aerospace applications. The disclosure relates to a single universal power electronic converter capable of converting an AC input voltage, such as a line to neutral input voltage of either 115 Vrms or 230 Vrms nominal to 28 V DC.

Abstract: A multi-cell battery pack may be designed to serve as a thermosiphon. Stated another way, multi-cell battery pack may be designed to incorporate a passive heat exchange technique based on natural convection, which circulates a substance (liquid, or gas such as air) without the necessity of a mechanical pump. In this way, insulating fluid in cavities between cells greatly enhances the likelihood of preventing a thermal runaway condition. The insulating fluid in cavities between cells may result in reduced arcing and the elimination of combustion within a battery housing.

Abstract: A power conversion system includes a power source, a matrix converter, and a controller. The power source is configured to produce an input power. The matrix converter is configured to convert the input power to output power and includes a plurality of normally-on switches and a plurality of normally-off switches. The controller is configured to control the plurality of normally-on switches and the plurality of normally-off switches to control the output power. The plurality of normally-on switches provide the input power directly as the output power when the controller is inactive.

Abstract: A universal AC to DC converter may be configured to convert alternating current (AC) to direct current (DC), such as for use in aerospace applications. The disclosure relates to a single universal power electronic converter capable of converting an AC input voltage, such as a line to neutral input voltage of either 115 Vrms or 230 Vrms nominal to 28 V DC.

Abstract: A system including a frequency shifted proportional-integral (PI) controller system utilizing input band-shifting, a PI control architecture and inverse band-shifting is disclosed. The frequency shifted PI controller system may eliminate errors and/or take control action based on past and present control errors. The feedback signal may be multiplied times sine of the theta position of the frequency of interest and the feedback signal may be multiplied times cosine of the theta position of the frequency of interest. Stated another way, the initial feedback signal is parsed into sine and cosine components at a particular frequency. This effectively band-shifts the feedback signal for treatment by the PI controller.

Abstract: A ripple compensation apparatus comprises a ripple detection unit to detect a ripple on a dual DC bus, a waveform generation unit to generate a modulated waveform based on a base waveform and the detected ripple, and a multi-phase control signal generation unit to receive the modulated waveform and to generate at least one pulse width modulated control signal based on the modulated waveform.

Abstract: A multi-level converter includes a plurality of alternating current (AC) terminals connected to an AC source or load, at least three direct current (DC) terminals connected to a multi-level DC source or load, and a plurality of solid-state switches that are selectively turned On and Off to connect each of the plurality of AC terminals to one of the DC terminals. A controller provides PWM control signals to the solid-state switches. The controller utilizes space vector modulation to organize the various switching state configurations, and increments the switching states during a first half of the switching period and decrements the switching states during a second half of the switching period to center-align the PWM signals provided about the center of the switching period. The switching states utilized during the switching period dictate the PWM control signals provided to the plurality of switches employed in the three-level converter.

Abstract: A power converter system includes an interleaved power converter having a plurality of parallel-connected phase legs between DC terminals and an AC terminal. A plurality of parallel-connected inductors are each connected to one of the plurality of parallel-connected phase legs to provide a summed output of the parallel-connected phase legs to the AC terminal. A controller generates PWM signals used to control the state of each of the plurality of phase legs by comparing a carrier signal to a reference signal, wherein a period of the carrier signal is randomly varied from a nominal period.