wechselstromgenerator or power source with wechselstromgenerator and rectifier

摘要

1,170,767. Alternators. NATIONAL RESEARCH DEVELOPMENT CORP. 11 Oct., 1967 [21 Oct., 1966], No. 47426/66. Heading H2A. An alternator has a very small air-gap so that it has a drooping characteristic caused by armature reaction and so is suitable for constant current load. In addition, the field windings are uniformly distributed over the rotor so that the output current, reflecting this square-wave ampere-turn distribution because of the large armature-reaction, also tends to be of squarewave shape. This makes it especially suitable for rectification. In effect, the close air-gap and low load impedance means that the working flux is very low, and the output current is a reflection of the rotor current. The machine resembles a current transformer while the conventional alternator resembles a voltage transformer. The machine is switched off by being short-circuited. Six phases may be derived from three stator coils by using bifilar wire. Alternatively, nine phases may be used in three rectified series groups. The excitation may be currentcompounded.