To generate a PWM signal, as an on/off signal of a semiconductor switch that constitutes a power conversion main circuit, by comparing a modulation wave command based on an input voltage waveform command of the power conversion main circuit with a carrier wave having changes from a lower limit to an upper limit and from the upper limit to the lower limit for an integral number of times per one cycle of an AC power supply, where the carrier wave has characteristics such that one change time from the lower limit to the upper limit and then returning to the lower limit is constant, and a time ratio between a change time from the lower limit to the upper limit and a change time from the upper limit to the lower limit changes periodically.

An apparatus comprises a power electronic energy conversion system comprising a first energy storage device configured to store DC energy and a first voltage converter configured to convert a second voltage from a remote power supply into a first charging voltage configured to charge the first energy storage device. The apparatus also includes a first controller configured to control the first voltage converter to convert the second voltage into the first charging voltage and to provide the first charging voltage to the first energy storage device during a charging mode of operation and communicate with a second controller located remotely from the power electronic energy conversion system to cause a second charging voltage to be provided to the first energy storage device during the charging mode of operation to rapidly charge the first energy storage device.

A track-bound vehicle converter comprises a block-wave generator (20) configured to be connected to a direct voltage source (21) and connected to a series resonance link (34), or to an inductive link, for providing the input of a direct converter (41) with semi sinusoidal current pulses. The direct converter has at least one phase leg (42-44) having on one hand one switch (45-47) connected to the link (34) and able to block voltages in both directions thereacross and conduct current in both directions therethrough and on the other a capacitor (48-50) connected in series therewith. The voltage across the capacitor (48-50) of the direct converter is used to provide a converter output with an alternating voltage.

An apparatus comprises a power electronic energy conversion system comprising a first energy storage device configured to store DC energy and a first voltage converter configured to convert a second voltage from a remote power supply into a first charging voltage configured to charge the first energy storage device. The apparatus also includes a first controller configured to control the first voltage converter to convert the second voltage into the first charging voltage and to provide the first charging voltage to the first energy storage device during a charging mode of operation and communicate with a second controller located remotely from the power electronic energy conversion system to cause a second charging voltage to be provided to the first energy storage device during the charging mode of operation to rapidly charge the first energy storage device.

An apparatus comprises a power electronic energy conversion system comprising a first energy storage device configured to store DC energy and a first voltage converter configured to convert a second voltage from a remote power supply into a first charging voltage configured to charge the first energy storage device. The apparatus also includes a first controller configured to control the first voltage converter to convert the second voltage into the first charging voltage and to provide the first charging voltage to the first energy storage device during a charging mode of operation and communicate with a second controller located remotely from the power electronic energy conversion system to cause a second charging voltage to be provided to the first energy storage device during the charging mode of operation to rapidly charge the first energy storage device.

There is provided an electric traction system, comprising: a step-down transformer comprising a primary winding for operatively coupling to an AC power supply and a secondary winding which is inductively coupled to the primary winding; a traction converter module comprising a first input terminal and a second input terminal which are operatively coupled to the secondary winding, and a plurality of AC-to-AC power converters, each of which comprises first and second input nodes, configured to receive AC power and output nodes configured to supply AC power, wherein the first and second input nodes, of the plurality of AC-to-AC power converters are electrically connected in series between the first input terminal and the second input terminal; and at least one electric motor configured to be driven by the traction converter module.

There is provided an electric traction system 1, comprising: a step-down transformer 35 comprising a primary winding 36 for operatively coupling to an AC power supply 40 and a secondary winding 37 which is inductively coupled to the primary winding 36; a traction converter module 2 comprising a first input terminal 4 and a second input terminal 6 which are operatively coupled to the secondary winding 37, and a plurality of AC-to-AC power converters 11, each of which comprises first and second input nodes 3, 5 configured to receive AC power and output nodes 9 configured to supply AC power, wherein the first and second input nodes 3, 5 of the plurality of AC-to-AC power converters 11 are electrically connected in series between the first input terminal 4 and the second input terminal 6; and at least one electric motor 25 configured to be driven by the traction converter module 2.