Doubly-fed induction machine drive with voltage-source converter in the rotor

A new speed control technique for doubly-fed induction machine drives using a phase-controlled rectifier and a voltage-source converter in the rotor circuit of the wound rotor induction machine is proposed.; By controlling the frequency of the voltage fed to the rotor to ensure that the sum of this frequency and frequency corresponding to the rotor speed equals the frequency of the stator voltage, and by adjusting the magnitude of the voltage fed to the rotor, the speed of the rotor can be controlled easily. It is found that the slip speed is approximately proportional to the magnitude of the voltage fed to the rotor.; The machine controlled under this technique can also operate in a regeneration mode and can be used to realize soft starting. This characteristic is particularly advantageous for large capacity electrical machine drives. The dynamic behaviour is simulated using the d-q model.