Abstract: A trolley interfacing device for interfacing a traction load to a voltage source is presented. The trolley interfacing device includes a first charging unit coupled in parallel to the voltage source. Further, the trolley interfacing device includes a second charging unit coupled in parallel to the traction load, where the second charging unit includes at least one inductor. Also, the trolley interfacing device includes a pre-charging unit coupled in parallel to the second charging unit and configured to pre-charge the first charging unit with a voltage across the at least one inductor prior to electrically coupling the first charging unit to the voltage source. In addition, the trolley interfacing device includes a voltage converting unit disposed between the first charging unit and the second charging unit and configured to step down a voltage provided by the voltage source to the traction load.

Abstract: A power electronic device includes at least one inductor configured to couple to a first capacitor and a second capacitor. The power electronic device includes a controller configured to control a first current conducting through the inductor and a second current conducting through the inductor. The first and second currents conduct in opposite directions with respect to each other, and the first and second currents interact with each other through the inductor such that a net direct current (DC) component through the inductor is approximately zero.

Abstract: A trolley interfacing device for interfacing a traction load to a voltage source is presented. The trolley interfacing device includes a first charging unit coupled in parallel to the voltage source. Further, the trolley interfacing device includes a second charging unit coupled in parallel to the traction load, where the second charging unit includes at least one inductor. Also, the trolley interfacing device includes a pre-charging unit coupled in parallel to the second charging unit and configured to pre-charge the first charging unit with a voltage across the at least one inductor prior to electrically coupling the first charging unit to the voltage source. In addition, the trolley interfacing device includes a voltage converting unit disposed between the first charging unit and the second charging unit and configured to step down a voltage provided by the voltage source to the traction load.

Abstract: A power electronic device includes at least one inductor configured to couple to a first capacitor and a second capacitor. The power electronic device includes a controller configured to control a first current conducting through the inductor and a second current conducting through the inductor. The first and second currents conduct in opposite directions with respect to each other, and the first and second currents interact with each other through the inductor such that a net direct current (DC) component through the inductor is approximately zero.

Abstract: A power converter control system includes primary bridge controller that is configured to actuate a first plurality of gate drive units that switch a first plurality of power elements in a primary bridge of a power converter. The control system further includes a secondary bridge controller separate from the primary bridge controller that is configured to actuate a second plurality of gate drive units to switch a second plurality of power elements in a secondary bridge of the power converter.

Abstract: A load tap changer includes a mechanical switch, a semiconductor switch and an impedance branch or an uncontrolled semiconductor switch. The mechanical switch is connected to a power terminal of a voltage conversion device to carry an electric current and is activated to switch from a first tap to a second tap of the voltage conversion device when a tap change signal is received. The semiconductor switch is then connected between the first tap and the power terminal of the voltage conversion device and is disconnected before the mechanical switch is connected to the second tap. The impedance branch or the uncontrolled semiconductor switch is connected between the second tap and the power terminal of the voltage conversion device before the mechanical switch is connected to the second tap. The impedance or the uncontrolled semiconductor switch is disconnected after the mechanical switch is connected to the second tap.

Abstract: A power converter control system includes primary bridge controller that is configured to actuate a first plurality of gate drive units that switch a first plurality of power elements in a primary bridge of a power converter.

Abstract: A load tap changer includes a mechanical switch, a semiconductor switch and an impedance branch or an uncontrolled semiconductor switch. The mechanical switch is connected to a power terminal of a voltage conversion device to carry an electric current and is activated to switch from a first tap to a second tap of the voltage conversion device when a tap change signal is received. The semiconductor switch is then connected between the first tap and the power terminal of the voltage conversion device when the tap change signal is received and is disconnected before the mechanical switch is connected to the second tap. The impedance branch or the uncontrolled semiconductor switch is connected between the second tap and the power terminal of the voltage conversion device before the mechanical switch is connected to the second tap. The impedance or the uncontrolled semiconductor switch is disconnected after the mechanical switch is connected to the second tap.

Abstract: A multilevel converter includes a plurality of phase legs each having at least two inner switching devices, at least two outer switching devices, at least two clamping diodes, a split DC link and a switching device failure detection circuit. The switching device failure detection circuit includes a logic module for each of the switching devices, a voltage calculation module and a failure detection algorithm. The logic module generates a blocking state logic signal by comparing a switching device voltage and a threshold reference voltage and the voltage calculation module determines an expected voltage blocking state for each of the switching devices based on the gate drive signals of the switching devices and an output current direction. The failure detection algorithm detects a failure condition in any of the switching devices based on the blocking state logic signals and the expected voltage blocking states of the switching devices.

Abstract: A multilevel converter includes a plurality of phase legs each having at least two inner switching devices, at least two outer switching devices, at least two clamping diodes, a split DC link and a switching device failure detection circuit. The switching device failure detection circuit includes a logic module for each of the switching devices, a voltage calculation module and a failure detection algorithm. The logic module generates a blocking state logic signal by comparing a switching device voltage and a threshold reference voltage and the voltage calculation module determines an expected voltage blocking state for each of the switching devices based on the gate drive signals of the switching devices and an output current direction. The failure detection algorithm detects a failure condition in any of the switching devices based on the blocking state logic signals and the expected voltage blocking states of the switching devices.