|Traction control G., Vehicle control technology Div.||Superconducting materials G., Materials technology Div.|
High Tc superconducting wires such as Bi2223 have made great progress in recent years. As a result, a prototype superconducting transformer rated around 1 MVA was manufactured. Its merits are lightweight and high efficiency. We have carried out a rough design study of a superconducting traction transformer to evaluate its merit. This work was carried out in conjunction with Kyushu University .
2. Premise for a design study
We assumed the specification of the transformer as Table 1 in consideration of the current design for Shinkansen type rolling stock.
|Input power||3 MVA|
|Voltage (prim./second.)||25 kV / 1 kV|
|Current (prim./second.)||120 A / 1 kA~3|
We assumed four cases for the design study. When compared with the present wire, the Ic and AC loss are:
|Case1:||Ic the same, AC loss the same|
|Case2:||Ic twice, AC loss the same|
|Case3:||Ic the same, AC loss 1/10|
|Case4:||Ic twice, AC loss 1/10|
In all cases, we first determined the dimensions of windings and core. Then we carried out magnetic field distribution analysis for the windings and calculated the AC loss, which is a function of the magnetic field applied to the windings. Finally we calculated the weight of transformer including a refrigerator. The results are shown in Fig.2. As for the cases 1 and 2, the weight is around 2600 kg which is slightly lighter than that of conventional transformer. In the case 4, the minimum weight is around 1800 kg, 30% lighter.
|AC loss||----||299 W|
|Other loss||131 kW||170 W|
|Refrigerator input||----||12 kW|