| 主权项 |
1. A field winding type synchronous motor comprising a stator which is connected to an electric power system, a rotor with field windings wound on a shaft, a brushless AC exciter mounted on the shaft, and a rectification circuit which rectifies an output of the brushless AC exciter and gives a DC current to DC lines, the field windings being connected to the DC lines,
wherein a first circuit is connected in parallel with the field windings, the first circuit including a discharge resistor and a parallel circuit formed of a diode and a first switching device, wherein the discharge resistor and the parallel circuit are connected in series, and a second switching device is provided in series to one of the DC lines connecting the first circuit and the rectification circuit, wherein the first switching device is controlled to be open or closed by a potential obtained by dividing an induced voltage induced in the field windings by a resistor and a connection is made from a node of a voltage divided potential via a diode to a node, which is adjacent to the rectification circuit, on the one of the DC lines with the second switching device connected thereon, and wherein the second switching device is closed when the synchronous motor has accelerated nearly to a synchronous speed. |
