Electric traction system

A method of operating an electric traction system, comprising:

• electrically coupling a primary winding of a step-down transformer of the electric traction system to an AC power supply, wherein the step-down transformer further comprises a secondary winding which is inductively coupled to the primary winding;
• electrically coupling a first input terminal and a second input terminal of a traction converter module of the electric traction system to the secondary winding, the traction converter module comprising 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;
• driving a multi-phase electric motor which includes more than three phases using the traction converter module, wherein:
• the plurality of AC-to-AC power converters comprise a first AC-to-AC power converter and a second AC-to-AC power converter, and the multi-phase electric motor comprises a first set of stator windings and a second set of stator windings, wherein driving the multi-phase electric motor comprises:
• electrically coupling the output nodes of the first AC-to-AC power converter to the first set of stator windings, and electrically coupling the output nodes of the second AC-to-AC power converter to the second set of stator windings;
• and
• supplying AC power by the output nodes of the first and second AC-to-AC power converters to the multi-phase electric motor so as to drive the multi-phase electric motor.