| Abstract |
In this paper a simple field orientated control method for induction machines fed by current source inverters is presented. The method is based on a feed forward control of the rotor frequency. A load-angle control circuit is added, which ensures by means of a fundamental frequency model that the necessary mean load-angle is suppIied to the induction machine. The dc-link current and the drive's speed are measured and used as inputs to the model. For sufficiently high speeds the control operates in the well known fundamental switching mode. In the lower frequency range the feed forward inverter control, which is subordinated to the closed loop control, generates a pulse pattern, synchronized to the fundamental frequency of the current, to reduce torque pulsations of low order. A free running mode of operation is performed in the range of even lower frequencies down to zero, where also a special shaping of the dc-link current is applied. The control is executed in a microcomputer system. The steady state and dynamic behaviour of the drive are demonstrated by virtue of measurements on a test stand in both the pulsing and in the fundamental switching mode. |
