DSP implementation of a variable speed drive using fuzzy logic based voltage injection method for wound-rotor induction machines

The speed control at large range for wound-rotor induction machines can be implemented by using different vector based methods from either or both the stator and the rotor side. One of these is to apply voltage with slip frequency on rotor windings through the rings. But, throughout the application, dangerous effects on the machine dynamics occur when effective value of the voltage applied on rotor windings is not adjusted by any intelligent control system especially at the application moment. In this study, firstly, the effects on the instantaneous rotor current and induced torque waveforms throughout the voltage injecting in the rotor windings are examined by simulations and experiments. Afterwards, the determined transient and harmful effects on the mentioned dynamics are tried to reduce by the fuzzy logic based control system using DSP. For the experimental studies, an IGBT inverter fed by DC link converter in rotor side is designed and employed. Thus, power converter rating is reduced. In the control system, TMS320F2812 DSP is used together with fuzzy logic based space vector pulse width modulated (SVPWM) inverter in order to control of amplitude and frequency of the injected voltage with same phase in accordance with the voltage induced in rotor circuit. The power flow between rotor windings and system in which stator side is directly connected to the grid is analyzed at different operation mode. A large range speed controller system with power recovery drive is implemented not only braking in regenerative region but holding the speed at the reference under unexpected load condition changing suddenly as well. For simulation studies, a C/C++ algorithm is developed in order to predict the performance of proposed model and results supported by experimental studies are presented and discussed. © 2008 Praise Worthy Prize - All rights reserved