Induction motor drives are at the heart of modern industrial and commercial applications. With conventional control techniques, induction motor drives have shown less than expected dynamic performance. With vector control techniques emerging as potential replacement in induction motor drives, this paper aims at highlighting various vector control strategies. Direct and indirect vector controls along with sensorless vector control are presented. Various speed control techniques are presented through the use of conventional controllers and Intelligent Controllers. A critical analysis and comparison is made with other control strategies.
1. Field oriented control
2. Sensorless vector control
3. Direct torque control
5. Parameter estimation
Fig. 1. Block diagram of general vector control scheme
The use of vector control has been presented for Induction motor drives. A number of vector control schemes have been presented with merits and demerits of each. Different controllers (conventional and intelligent controllers) have been used in various schemes of vector control strategy. Potentially DTC is proving to be superior to other vector control techniques. Contrast to field oriented controller, it is more robust, does not require any transformation, current controller, or rotor position measurement. However, an improvement in torque ripples is the demand of this scheme. Sensorless vector control offers low cost and more reliability, but operation of this scheme in low speed region is one of its biggest drawbacks.
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