Abstract: A phase leg for a multilevel inverter includes a first direct current lead, an outer solid-state switch, an inner solid-state switch, and a midpoint-clamping device. The outer solid-state switch device is connected to the first direct current lead. The inner solid-state switch is connected in series with the outer solid-state switch. The midpoint-clamping device is a bi-directional current flow device connected between a second DC lead and a node between the inner and outer solid-state switches for reducing conduction losses associated with current flowing through the phase leg.

Abstract: A transformer assembly includes a housing with a sealed housing interior, a transformer disposed within the housing interior and having a core with windings wrapped about the core, and a condenser mounted to the housing. The condenser is in fluid communication with the housing interior. A surface of the windings bounds a coolant channel extending between the windings and the condenser to convey coolant of a first phase to the condenser and receive coolant of a second phase from the condenser.

Abstract: A method of controlling an inverter includes receiving output voltage target waveforms for phases of an inverter, generating uncompensated midpoint duty cycle waveforms for the inverter phases, selecting an uncompensated midpoint duty cycle waveform for one of the inverter phases based on the magnitudes of the uncompensated midpoint duty cycle waveforms, and applying a compensation signal to the selected uncompensated midpoint duty cycle waveform. An inverter controller and inverter employ the method for generating switch command signals for solid-state switch devices of the inverter.

Abstract: A method of controlling an inverter includes receiving a target waveform for output voltage of an inverter phase, calculating a phase bias for an inverter phase using the target waveform, biasing the target waveform using the phase bias, and generating a switching device command signal by comparing the biased target waveform to a carrier waveform. The switching device command signal has a switching patter that reduces midpoint current in an inverter input lead and common mode voltage in an inverter output lead.

Abstract: A method of controlling an inverter includes receiving output voltage target waveforms for phases of an inverter, generating uncompensated midpoint duty cycle waveforms for the inverter phases, selecting an uncompensated midpoint duty cycle waveform for one of the inverter phases based on the magnitudes of the uncompensated midpoint duty cycle waveforms, and applying a compensation signal to the selected uncompensated midpoint duty cycle waveform. An inverter controller and inverter employ the method for generating switch command signals for solid-state switch devices of the inverter.

Abstract: A method of converting power includes receiving alternating current (AC) at the first phase leg set of a power conversion system having first and second phase legs sets connected by direct current (DC) leads. The first phase leg set rectifies the received AC power into DC power by switching outer switches of the first phase leg set into an off state. The DC lead conveys the DC power from the first phase leg set to the second phase leg set. The second phase leg set inverts the DC power into AC power.

Abstract: A phase leg for a multilevel inverter includes a positive DC lead, a first outer MOSFET connected to the positive DC lead, a first inner IGBT connected to the first outer MOSFET, a second inner IGBT connected to the first inner IGBT, and a second outer IGBT connected to the second inner IGBT. The first and second outer MOSFETs are superjunction MOSFETs voltage balanced by the first and second IGBTs for reducing voltage stress in the solid-state switch phase leg when the superjunction MOSFET and the IGBT are conducting current from the DC lead to the AC lead.

Abstract: A power converter includes a first set of transistors electrically connected in series, a second set of transistors electrically connected in series, and an AC link. The second set of transistors is electrically connected in parallel with the first set of transistors to form an H-bridge. The AC link is electrically connected between the first and second sets of transistors. A plurality of H-bridges are connected in parallel and a three-wire DC bus is electrically connected to the H-bridges.

Abstract: A transformer assembly includes a housing with a sealed housing interior, a transformer disposed within the housing interior and having a core with windings wrapped about the core, and a condenser mounted to the housing. The condenser is in fluid communication with the housing interior. A surface of the windings bounds a coolant channel extending between the windings and the condenser to convey coolant of a first phase to the condenser and receive coolant of a second phase from the condenser.

Abstract: A method of controlling a rectifier includes receiving a gain factor, receiving a ramp interval, and generating a rectifier switch control voltage. The rectifier switch control voltage is an over-modulated rectifier switch control voltage generated by a pulse width modulator using the gain factor. The amount of over-modulation in the rectifier switch control voltage is decreased during the ramp interval for reducing transient voltage overshoot events at the start of active rectification.

Abstract: A method of controlling an inverter includes receiving a target waveform for output voltage of an inverter phase, calculating a phase bias for an inverter phase using the target waveform, biasing the target waveform using the phase bias, and generating a switching device command signal by comparing the biased target waveform to a carrier waveform. The switching device command signal has a switching patter that reduces midpoint current in an inverter input lead and common mode voltage in an inverter output lead.

Abstract: A thermal stress reduction method includes ramping an electric power generator to start an aircraft engine, for a time period associated with the aircraft engine start sequence toggling a three-level inverter switch array to a three-level pulse width modulation mode, determining if a first time interval in the three-level pulse width modulation mode exceeded a predetermined three-level pulse width modulation mode interval, in response to the first time interval exceeding the three-level pulse width modulation mode interval, toggling the three-level inverter switch array to a two-level pulse width modulation mode, determining if a second time interval in the two-level pulse width modulation mode exceeded a predetermined two-level pulse width modulation mode interval and in response to the second time interval exceeding the two-level pulse width modulation mode interval, toggling the three-level inverter switch array to the three-level pulse width modulation mode.

Abstract: A thermal stress reduction method includes ramping an electric power generator to start an aircraft engine, for a time period associated with the aircraft engine start sequence toggling a three-level inverter switch array to a three-level pulse width modulation mode, determining if a first time interval in the three-level pulse width modulation mode exceeded a predetermined three-level pulse width modulation mode interval, in response to the first time interval exceeding the three-level pulse width modulation mode interval, toggling the three-level inverter switch array to a two-level pulse width modulation mode, determining if a second time interval in the two-level pulse width modulation mode exceeded a predetermined two-level pulse width modulation mode interval and in response to the second time interval exceeding the two-level pulse width modulation mode interval, toggling the three-level inverter switch array to the three-level pulse width modulation mode.

Abstract: An electrical system includes a converter having an H-bridge. The H-bridge includes a first set of transistors electrically connected in series and a second set of transistors electrically connected in series. The first set and the second set of transistors are electrically connected in parallel. The H-bridge defines three available switching states such that a common mode voltage across the H-bridge at each switching state is zero. A method for reducing electromagnetic interference (EMI) in pulse-width modulation (PWM) converters includes diagonally switching transistors of the H-bridge. Diagonally switching the transistors of the H-bridge includes constraining available switching states of the H-bridge to only include the switching states with zero common-mode voltage such that common-mode voltage on an AC output side of the H-bridge is zero.

Abstract: A method of converting power includes receiving alternating current (AC) at the first phase leg set of a power conversion system having first and second phase legs sets connected by direct current (DC) leads. The first phase leg set rectifies the received AC power into DC power by switching outer switches of the first phase leg set into an off state. The DC lead conveys the DC power from the first phase leg set to the second phase leg set. The second phase leg set inverts the DC power into AC power.

Abstract: A phase leg for a multilevel inverter includes a first direct current lead, an outer solid-state switch, an inner solid-state switch, and a midpoint-clamping device. The outer solid-state switch device is connected to the first direct current lead. The inner solid-state switch is connected in series with the outer solid-state switch. The midpoint-clamping device is a bi-directional current flow device connected between a second DC lead and a node between the inner and outer solid-state switches for reducing conduction losses associated with current flowing through the phase leg.

Abstract: A method of controlling a rectifier includes receiving a gain factor, receiving a ramp interval, and generating a rectifier switch control voltage. The rectifier switch control voltage is an over-modulated rectifier switch control voltage generated by a pulse width modulator using the gain factor. The amount of over-modulation in the rectifier switch control voltage is decreased during the ramp interval for reducing transient voltage overshoot events at the start of active rectification.

Abstract: A phase leg for a multilevel inverter includes a positive DC lead, a first outer MOSFET connected to the positive DC lead, a first inner IGBT connected to the first outer MOSFET, a second inner IGBT connected to the first inner IGBT, and a second outer IGBT connected to the second inner IGBT. The first and second outer MOSFETs are superjunction MOSFETs voltage balanced by the first and second IGBTs for reducing voltage stress in the solid-state switch phase leg when the superjunction MOSFET and the IGBT are conducting current from the DC lead to the AC lead.

Abstract: A power converter includes a first set of transistors electrically connected in series, a second set of transistors electrically connected in series, and an AC link. The second set of transistors is electrically connected in parallel with the first set of transistors to form an H-bridge. The AC link is electrically connected between the first and second sets of transistors. A plurality of H-bridges are connected in parallel and a three-wire DC bus is electrically connected to the H-bridges.

Abstract: A bobbin for spacing windings around an inductor core includes an interior spacer defining an exterior surface for coupling interior spacer with an annular inductor core and an interior facing surface opposing the exterior surface for receiving inductor windings. The interior spacer has a thickness profile between the exterior and interior facing surfaces for spacing the windings inward from the inductor core to reduce magnetic fringe flux effects on the windings. An inductor body includes an inductor core coupled to bobbin. A wound inductor includes windings wrapped around the inductor body formed by the inductor core and bobbin.