Trolley interfacing device having a pre-charging unit

A trolley interfacing kit for interfacing a traction load to a voltage source, comprising:

• a pre-charging unit configured to pre-charge a first charging unit with a voltage across at least one inductor in a second charging unit,
• wherein the first charging unit includes one or more first switches deactivated to decouple the voltage source from the first charging unit,
• wherein the pre-charging unit includes several second switches connected in a series with each other and coupled in parallel to a voltage converting unit and the second charging unit, and
• wherein the pre-charging unit is configured to be repeatedly activated and deactivated to pre-charge the first charging unit with the provided voltage to a voltage value equal to a first threshold value, and
• wherein the pre-charging unit is configured to reduce a surge current from being conducted from the voltage source to one or more capacitors of the first charging unit responsive to activation of the one or more first switches, the pre-charging unit configured to reduce the surge current by pre-charging the one or more capacitors in the first charging unit prior to the activation of the one or more first switches.

A method for interfacing a traction load to a voltage source, the method comprising:

• deactivating one or more first switches to decouple a first charging unit of a trolley interfacing device from the voltage source;
• activating a pre-charging unit of the trolley interfacing device to energize at least one inductor in a second charging unit of the trolley interfacing device, wherein the pre-charging unit includes several second switches connected in a series with each other and connected in parallel to the second charging unit;
• and
• deactivating the pre-charging unit to provide a voltage across the at least one energized inductor to the first charging unit when the one or more first switches is deactivated to decouple the voltage source from the first charging unit, wherein the first charging unit is pre-charged with the provided voltage to charge the first charging unit and prevent conduction of a surge current flow from the voltage source to the first charging unit while the first charging unit is operatively coupled to the voltage source by activating the one or more first switches.

A system for driving a traction load, the system comprising:

• a trolley interfacing device disposed between a voltage source and the traction load and configured to step down a DC voltage supplied from the voltage source to the traction load, wherein the trolley interfacing device comprises:
• a first charging unit including one or more capacitors, the first charging unit configured to be coupled in parallel to the voltage source through one or more first switches;
• a second charging unit comprising at least one inductor that is configured to be coupled in parallel to the traction load;
• a pre-charging unit including several second switches connected in a series with each other, the series of the second switches configured to be coupled in parallel to the second charging unit;
• and
• a voltage converting unit configured to be disposed between the first charging unit and the second charging unit, the voltage converting unit configured to step down a voltage provided by the voltage source to the traction load responsive to activation of the one or more first switches to couple the voltage source to the first charging unit through the one or more first switches,
• wherein the pre-charging unit is configured to reduce a surge current being conducted from the voltage source to the one or more capacitors of the first charging unit responsive to activation of the one or more first switches, the pre-charging unit configured to reduce the surge current by pre-charging the one or more capacitors in the first charging unit prior to the activation of the one or more first switches.