DSP-based field oriented control of a load commutated current source inverter (LCCSI)-fed AC motor drive

In the power range of above 1 MW, industrial AC drive load-commutated current source inverters (LCCSI) are controlled by simple methods like the combination of V/f ratio constant control at low frequency and V/f ratio constant-angle control at high frequency. This gives a good steady-state but poor dynamic performance. This paper describes a drive control of LCCSI-fed induction motors which is based on the principle of field oriented control. Along with taking into account the output capacitor's effect, the direct field oriented control referred to rotor flux fixed reference frame without a speed sensor is applied to decouple torque and flux generating currents and to overcome the problem of instability caused by the output capacitor. This control scheme is implemented by a 32 bit floating point Digital Signal Processor (DSP) chip-TMS320C30. The availability of this control scheme is verified by computer simulation and experimental results for a laboratory LCCSI-induction motor (10 HP) system.<
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