A switching system is disclosed having a switching arm with a high-side switch and a low-side switch. A control system switches the switching arm alternately between a first configuration, in which the high-side switch is open and the low-side switch is closed, and a second configuration, in which the high-side switch is closed and the low-side switch is open. The control system commands, for each switching operation, the opening of the switch that is initially closed, and then, at the end of a dead time, commands the closure of the switch that is initially open. The system has device for measuring a switch voltage present between the terminals of one of the switches. For each switching operation, the control system, following the command to open the switch initially closed, monitors the measured switch voltage, and determine the dead time for the switching operation based on the monitored switch voltage.

A bi-directional medium voltage converter topology includes an n-pulse line-interphase-transformer, LIT; a plurality of bi-directional medium voltage, MV converters connected to the LIT on an AC side thereof and connected in parallel on a DC side thereof; a bi-directional multi-stage DC/DC converter connected to the plurality of bi-directional MV converters; and a bi-directional low voltage, LV, DC/DC converter; wherein the multi-stage DC/DC converter and the LV DC/DC converter are connected to each other galvanically insulated.

A multi-pulse line-interphase transformer converter includes an electric part that includes magnetic components configured to be connected to a three-phase AC grid, and an electric part that includes a multi-phase voltage system configured to be connected to a common DC capacitor. The electric part splits each AC grid phase n times into two phases, resulting in a plurality of intermediate phases at an internal interface, each intermediate phase corresponding to a pulse of the multi-pulse line-interphase transformer converter. The intermediate phases are connected to the multi-phase voltage system. The multi-phase voltage system comprises bridges with actively controlled switches. The bridges are connected in parallel to the common DC capacitor.

A LIT-based bi-directional medium voltage converter topology includes active medium voltage switches that comprise low voltage switches connected in series and/or switch-cells in a cascode-configuration.

A power conversion device includes: a power converter including, for respective phases of AC, leg circuits each including a pair of arms connected in series, the arms including a plurality of converter cells which are connected in series and each of which has an energy storage element and a plurality of semiconductor elements, the leg circuits being connected in parallel between positive and negative DC terminals, the power converter being configured to perform power conversion between multiphase AC and DC; and a control unit. The control unit corrects an AC voltage command value for controlling AC voltage of the power converter, by a zero-phase-sequence voltage command value having a set amplitude and a set phase, and performs adjustment control for adjusting at least either the amplitude or the phase of the zero-phase-sequence voltage command value on the basis of electric energy variation in the arm.

A power conversion device includes: a power converter including, for respective phases of AC, leg circuits each including a pair of arms connected in series, the arms including a plurality of converter cells which are connected in series and each of which has an energy storage element and a plurality of semiconductor elements, the leg circuits being connected in parallel between positive and negative DC terminals, the power converter being configured to perform power conversion between multiphase AC and DC; and a control unit. The control unit corrects an AC voltage command value for controlling AC voltage of the power converter, by a zero-phase-sequence voltage command value having a set amplitude and a set phase, and performs adjustment control for adjusting at least either the amplitude or the phase of the zero-phase-sequence voltage command value on the basis of electric energy variation in the arm.

A control method of a three-phase multi-level inverter includes: determining a modulation ratio based on output of the three-phase multi-level inverter, where the modulation ratio indicates a ratio of an amplitude value of a sinusoidal modulation wave in pulse width modulation to an amplitude value of a carrier; generating, based on the modulation ratio and a modulation ratio threshold, a common-mode voltage regulation signal for regulating a common-mode voltage in phase voltages of the three-phase multi-level inverter; adding the common-mode voltage regulation signal and a differential-mode voltage regulation signal for regulating a differential-mode voltage in the phase voltages of the three-phase multi-level inverter to obtain a composite regulation signal, where the composite regulation signal is presented as a modulation wave for discontinuous pulse width modulation (DPWM); and generating, based on the composite regulation signal, drive signals for controlling switches of phases of the three-phase multi-level inverter.

A control method of a three-phase multi-level inverter includes: determining a modulation ratio based on output of the three-phase multi-level inverter, where the modulation ratio indicates a ratio of an amplitude value of a sinusoidal modulation wave in pulse width modulation to an amplitude value of a carrier; generating, based on the modulation ratio and a modulation ratio threshold, a common-mode voltage regulation signal for regulating a common-mode voltage in phase voltages of the three-phase multi-level inverter; adding the common-mode voltage regulation signal and a differential-mode voltage regulation signal for regulating a differential-mode voltage in the phase voltages of the three-phase multi-level inverter to obtain a composite regulation signal, where the composite regulation signal is presented as a modulation wave for discontinuous pulse width modulation (DPWM); and generating, based on the composite regulation signal, drive signals for controlling switches of phases of the three-phase multi-level inverter.

In an example embodiment, a system includes an inverter configured to operate in at least one of a charging mode or a drive mode, a cascaded direct current (DC)-DC converter, the DC-DC converter including a first portion of the inverter and at least one controller configured to selectively couple the first portion of the inverter to a first portion of the cascaded DC-DC converter during the charging mode, and selectively couple the inverter to a second portion of the cascaded DC-DC converter during the drive mode.

In an example embodiment, a system includes an inverter configured to operate in at least one of a charging mode or a drive mode, a cascaded direct current (DC)-DC converter, the DC-DC converter including a first portion of the inverter and at least one controller configured to selectively couple the first portion of the inverter to a first portion of the cascaded DC-DC converter during the charging mode, and selectively couple the inverter to a second portion of the cascaded DC-DC converter during the drive mode.