Starting Control Strategy For A Three Stage Synchronous Machine

Variable frequency AC power system becomes one of the main development direction withsimple construction, small volume, light weight, high reliability, low maintence and operation cost,easy to implement starting and generating. The three-stage synchronous machine has been commonlyused in the aerospace power systems, and it is also widely used in the variable frequency AC powersystem, which has starting and generating function. We must solve the excitation problem of the mainexciter and choose appropriate starting control strategy for the main motor of the three-stagesynchronous machine. For the purpose, this paper focuses on the excitation control technology andstarting control technology of the three-stage synchronous machine in start mode.A novel structure of the three-stage synchronous machine with open excitation windings isproposed firstly. The mathematical models of the main motor and the main exciter are discussed, theexcitation and starting working principle are described briefly. Then, the working performance of themain exciter is analyzed, and the selection principles of the AC excitation frequency and the switchingpoint from AC to DC excitation are put forward in this paper.The AC and DC excitation control method of the dual inverter is researched in detail based onthe idea of vector control. In order to obtain better field effect, the dead-time effect of the dual inverteris studied, and a dead-time compensation control strategy is proposed. In order to facilitate thealgorithm, the excitation control process based on SVPWM is simplified.On the basis, the simulation model of the three-stage synchronous machine starting controlsystem is built to verify the control method in this paper, and the excitation performance and thestarting process are analyzed. Besides, the digital excitation controller and starting controller based onTMS320F28335is constructed, the hardware and software design process is introduced. Finally, theexcitation and starting process is validated by experiments. Simulation and experimental results showthat the mentioned control strategy is feasible.