Sanjay B. Bodkhe and Mohan V. Aware
DC link current, phase currents reconstruction, three-phase induction motor, current sensor, algorithm, current regulation, field-oriented control, hysteresis modulation
This paper presents a new algorithm for the reconstruction of phase currents of an inverter-fed, three-phase induction motor from its dc link current. In conventional current-regulated induction motor drive, the phase currents are actually measured by using current sensors which are connected on the stator side. To reduce the number of sensors, different methods have been reported in literatures which are used for the reconstruction of phase currents from dc link current measurement. These methods are based either on the modification of pulse-width-modulation pattern or they consist of a machine model/load model-based observer and hence they have drawbacks like higher switching loss and increased sensitivity to parameter variations. The algorithm proposed in this paper makes use of simple logic gates and if–else statements and as a result, the drawbacks associated with conventional methods are eliminated. It also carries out auto-calibration of dc link current to remove the unwanted dc offsets that result due to asymmetry in switching of semiconductor devices. The proposed algorithm is tested on a 2.2 kW, current-regulated, field-oriented control, induction motor drive by using Matlab/Simulink software. The simulation results show good agreement between the reconstructed waveforms and actual waveforms under different operating conditions. This algorithm can be easily implemented by using any low-cost digital signal processor and one dc current sensor.
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