High-availability multicurrent power supply system for the traction unit of a railway locomotive

A multicurrent power supply system for a locomotive having 2N (meaning N multiplied by 2) motors M.sub.1 through M.sub.2N and a plurality of capacitors, where N is an integer greater than or equal to 2, the system comprising 2N pairs of voltage converters respectively associated with the 2N motors and identified sequentially as pair 1 through pair 2N of voltage converters, each of said motors being powered by an inverter connected to the terminals of a respective one of said capacitors which is connected on parallel therewith, and each of said pairs of converters comprises a first voltage converter and a second voltage converter which are connected in parallel with the terminals of one of said capacitors;

• when the locomotive is to be powered with AC, the midpoint of the first voltage converter in each pair of converters is connected to the midpoint of the second converter of the same pair in such a manner as to enable each of the pairs of converters to form a 4-quadrant converter, said connection being implemented via the secondary winding of a transformer whose primary winding is connected directly to the terminals of an AC power supply and a section switch in the closed position;
• wherein:
• a) when the locomotive is powered with DC at a voltage that is greater than the power supply voltage of said motors, and assuming that i takes on all values between 1 and N, inclusive:
• i) the midpoint of the first converter of each pair 2i-1 (meaning i multiplied by 2, the result minus 1) of voltage converters is connected to the high potential point of a respective one of said pairs 2i (meaning i multiplied by 2) of voltage converters via an inductor and the midpoint of the first converter of each pair 2i of voltage converters is connected to the low potential point of a respective one of said pairs 2i-1 of voltage converters via an inductor;
• ii) the midpoint of the second converter of each pair 2i-1 of voltage converters is connected to the high potential point of a respective one of said pairs 2i+2 of voltage converters via an inductor and the midpoint of the second converter of each pair of voltage converters 2i is connected to the low potential point of a respective one of said pairs 2i+1 of voltage converters via an inductor;
• and
• iii) the midpoint of the second converter of the pair 2N-1 of voltage converters is connected to the high potential point of the pair 2 of voltage converters via an inductor and the midpoint of the second converter of the pair 2N of voltage converters is connected to the low potential point of the pair 1 of voltage converters via an inductor;
• such that said voltage converters operate as voltage-lowering choppers;
• and
• b) when the locomotive is powered with DC at a voltage lower than the power supply voltage of said motors, and still assuming that i takes on all values between 1 and N, inclusive;
• the midpoints of the first and second converters of each pair 2i-1 of voltage converters are connected to the low potential point of a respective one of said pairs 2i of voltage converters via respective inductors, and the midpoints of the first and second converters of each pair 2i of voltage converters are connected to the high potential point of a respective one of said pairs 2i-1 of voltage converters via respective inductors;
• and
• in such a manner that said voltage converters operate as voltage-raising choppers.