| 摘要 |
PURPOSE:To protect field winding without requiring any temperature sensor by stopping the operation of a field chopper when the temperature of the field winding, detected based on the conduction ratio, reaches a predetermined level. CONSTITUTION:Power is fed from a stringing 1 through a current collector 2 to a reactor 4 and a capacitor 5, where AC component is removed, thence fed to an armature winding 6 and a field winding 9. Armature current is controlled by means of an armature chopper control circuit 13 through an armature chopper 7, whereas field current is controlled by means of a field chopper control circuit 14 through a field chopper 10. Resistance of the field winding 9 is calculated based on the conduction ratio gammaF of the field chopper 10, field current and field voltage, and then the temperature of the field winding 9 is calculated based on thus calculated resistance. When thus calculated temperature reaches a predetermined level, operation of the field chopper 10 is stopped. |
