Synchronous Mode Operation in Electrical Machine with DC Stator Excitation 2013-01-1412
In transport applications, the synchronous motors are used for the power drives, because of their high operating efficiency, and controllable power factor. Brushless electrical machine with DC stator excitation have on the stator the armature and excitation windings. Rotor is a salient pole construction with laminated core and without coils. On base of this machine can be realized the DC machine. In the synchronous mode operation, there is no need the sensor of rotor position. It is need only alternative current (AC) voltage source. The advantages of the synchronous machine with DC stator excitation are: the simple brushless design, and controllable field excitation. In this paper, we consider the physical principle operation of a new machine with DC stator excitation in the synchronous mode operation. For analysis in a synchronous mode operation, the simplified model of electrical machine in steady state condition is used. It is also suggested design of two and three phase machines by using two or three one phase machine on one shaft. In this case, there is no common rotating magnetic field. There is only addition of torques of machines mounted on the same shaft. For qualitative verification of synchronous mode operation in machine with DC stator excitation, the one phase machine was used. An AC inverter was used as an external AC voltage source for the electrical machine. The frequency of inverter was controlled by a sinusoidal signal from regular signal generator. Tests of the machine in synchronous mode operation show its synchronous motor properties.