An assembly according to an embodiment of the present disclosure includes, among other things, a synchronous machine including a rotating portion and a stationary portion, the rotating portion including at least one rotating diode coupled to a field winding, and the stationary portion including a stator winding and an exciter winding. A control unit includes a first gate and a second gate. The exciter winding is connected in series to the first gate and the second gate during a first operating mode to energize the exciter winding. The exciter winding is electrically connected in series to a first gate but is electrically disconnected from the second gate in a second, different operating mode to electrically disconnect the exciter winding from an exciter energy source. A method of operating a synchronous machine is also disclosed.