As for practical implementations, major devices include the main circuit VVVF, the auxiliary
circuit SIV (a static inverter), and the screw type motor driven air compressor. These devices were
installed for increased reliability.
For the VYVF inverter, an electric motor car has two pairs of three stage inverters, each of which
drives four inductive motors. As you know, an inverter is a that changes direct currents to altemating currents. It consists of a combination of GTO, a gate turn off thyristor and diode. It features a microcomputer used to control the GTO gate. System 103 used the main resister, cam shaft controller, etc. But these have all been eliminated by the contact-free point system to reduce weight and increase reliability.
Now let us look at the SIV. which is a static inverter. Its function is to supply electricity for interior illuminations, the air conditioner, heater, and other service devices. Its structure is a combination DC/DC converter of the chopper system and three stage inverter. The GTO used for elements features a natural cooling system with a heat pipe for greater reliability with the contact-free point system.
The function of the screw type compressor is to create compressed air for the air spring and brake. It structure is two screw rotors continuously compressing the air, and its discharge rate is 1,600 liters per minute. Compared with the conventional reciprocation system, the screw type converter weighs less, needs fewer expendable parts, and vibrates less. The use of the screw type converter has considerably increased the reliability of parts.
