Motors spread along the train
A Shinkansen has no locomotive: most cars carry their own motors, four per car. Power flows from the overhead wire through a chain of equipment down to every axle.
Collecting power
The pantograph presses against the overhead wire and picks up 25,000 V single-phase AC.
Main transformer
Under the floor, the heavy main transformer steps the voltage down to a level the power electronics can use.
Converter and VVVF inverter
The converter turns AC into DC, then the inverter switches it back into three-phase AC of variable voltage and frequency. Changing the frequency changes the motor speed smoothly from standstill to 300 km/h.
Motors on the bogie
Each axle has its own motor, hung on the bogie frame next to it. A gear unit on the axle passes the motor's torque to the wheels.
Inside the motor
The stator windings make a rotating magnetic field that drags the cage rotor round. A flexible coupling and a pinion driving a large gear (about 2.8 to 1) turn the axle.
Braking gives power back
When braking, the inverter makes the motors work as generators. The energy flows back up through the converter and transformer to the wire, for other trains to use.