Simple autonomous sensorless generation system with wound induction machine

The paper presents theory and results of tests of simple variable speed autonomous generating system. The system consists of double fed induction machine and power electronic converter. A topology and control system permits island operation. However, an initial excitation is needed. After, short, preliminary excitation, from the external source, the system operates autonomously and continuous excitation power is assuring by stator power. A control system is based on stator voltage space vector referred to rotating frame. The speed of the rotating frame responds to stator frequency. The system is controlled by rotor current that amplitude is adjusted by controller of the stator voltage component related to x axes, whereas the rotor current frequency is controlled by stator voltage component related to y axes. In this way the stator output voltage frequency is speed independent an the control system operates without any mechanical sensor. For design a simulation program PSIM with DLL files is applied. Results of controllers calculation in wide speed range are presented. Laboratory system was built and tested. As a controller a DSP SHARC^™ system with support ALTERA^™/FPGA is used. Results of laboratory tests presents the generating system in transients when a step load is applied.