This paper deals with a single stage solar powered speed sensorless vector controlled induction motor drive for water pumping system, which is superior to conventional motor drive. The speed is estimated through estimated stator flux. The proposed system includes solar photovoltaic (PV) array, a three-phase voltage source inverter (VSI) and a motor-pump assembly.
An incremental conductance (InC) based MPPT (Maximum Power Point Tracking) algorithm is used to harness maximum power from a PV array. The smooth starting of the motor is attained by vector control of an induction motor. The desired configuration is designed and simulated in MATLAB/Simulink platform and the design, modeling and control of the system, are validated on an experimental prototype developed in the laboratory.
- Speed Sensorless Control
- Stator Field-Oriented Vector Control
- Photovoltaic (PV)
- InC MPPT Algorithm
- Induction Motor Drive (IMD)
- Water Pump
Fig. 1. PV fed induction motor drive configuration
EXPECTED SIMULATION RESULTS:
Fig. 2. Starting and MPPT of PV array at 1000 W/m2
Fig. 3. Intermediate signals during starting at 1000 W/m2
Fig. 4. Simulation results during starting at 1000 W/m2 (a) Proposed drive (b) Waveforms showing sensed speed and estimated speed
Fig. 5. SPV array performance during decrease in insolation from 1000 W/m2 to 500 W/m2
Fig. 6. Dynamic performance during irradiance decrement from 1000 W/m2 to 500 W/m2 (a) Proposed drive (b) Waveforms showing sensed speed and estimated speed
Fig. 7. PV array performance on increasing insolation from 500 W/m2 to 1000 W/m2
Fig. 8. Dynamic performance during irradiance decrement from 500 W/m2 to 1000 W/m2 (a) Proposed drive (b) Waveforms showing sensed speed and estimated speed
A single stage solar PV array fed speed sensorless vector-controlled induction motor drive has been operated subjected to different conditions and the steady state and dynamic behaviors have been found quite satisfactory and suitable for water pumping. The torque and stator flux, have been controlled independently. The motor is started smoothly. The reference speed is generated by DC link voltage controller controlling the voltage at DC link along with the speed estimated by the feed-forward term incorporating the pump affinity law. The power of PV array is maintained at maximum power point at the time of change in irradiance. This is achieved by using incremental-conductance based MPPT algorithm.
The speed PI controller has been used to control the q-axis current of the motor. Smooth operation of IMD is achieved with desired torque profile for wide range of speed control. Simulation results have displayed that the controller behavior is found satisfactory under steady state and dynamic conditions of insolation change. The suitability of the drive is also verified by experimental results under various conditions and has been found quite apt for water pumping.
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