Synchronous machine with static converter - has three=phase excitation field rotating in opposite directions for upper and lower speed ranges

摘要

The synchronous machine has its stator terminals connected to a self-commutated static converter. The 3-phase excitation field rotates in the same sense as the desired direction of rotor rotation in the lower speed range whilst in the upper speed range it is switched over to rotate in the opposite direction to the desired rotor rotation. The switch over in the 3-phase field direction occurs when the stator voltage is equal to the sum of the minimum commutating voltage and twice the standstill stator voltage or when the stator frequency is equal to the sum of the minimum commutating frequency and twice the rotor frequency.