Reduced Sensor Based PV Array Fed Direct Torque Control Induction Motor Drive for Water Pumping

ABSTRACT:

 This paper aims at the design, control and implementation of a solar photovoltaic (PV) array fed speed sensorless direct torque control (DTC) of an induction motor drive (IMD) for water pumping in standalone as well as battery connected hybrid mode. This stator flux estimated by proposed flux observer, is used for speed estimation. A DC link current sensor is used to reconstruct the motor phase currents by modified active voltage vector. One voltage sensor for DC link voltage sensing and only one current sensor for DC link current sensing, are used in this system for standalone operation of the system. All other required quantities are estimated through these two sensed signals. The IMD is energized by a photovoltaic (PV) array, which is operated at maximum power point (MPP). A perturb and observe control algorithm with additional flow rate controller, is proposed for MPP, which tracks MPP throughout the operating range and provides the facility to control flow rate. The suitability of the system is judged through simulated results in MATLAB/Simulink as well as test results obtained on a prototype developed in the laboratory.

 KEYWORDS:

  1. PV Array
  2. Single Stage System
  3. Perturb and Observe (P&O) Algorithm
  4. Direct Torque Control (DTC)
  5. Speed Sensorless
  6. Current Reconstruction
  7. Induction Motor
  8. Submersible Water Pump

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1 Scheme of proposed PV-battery system

EXPECTED SIMULATION RESULTS:

Fig. 2 Bode plot showing the frequency response of flux observer with the

conventional technique

(a)                                               (b)

Fig. 3 Performance indices: (a) PV array during starting to steady-state at

1000W/m2 (b) IMD indices at 1000W/m2

(a)

(b)

                                                (c)                                (d)

(e)

Fig. 4 Performance indices during insolation change (a) PV array:1000W/m2-

500W/m2 (b) Induction motor drive:1000W/m2-500W/m2 (c) PV array:

500W/m2-1000W/m2 (d) Induction motor drive: 500W/m2-1000W/m2

(e) PV array:100W/m2-1000W/m2 (f) Induction motor drive:

100W/m2-1000W/m2

 

(a)

(b)

(c)

Fig. 5 Simulation results at rated insolation and (a) Rated flow rate (b) 80%

of rated flow rate (c) 60% of rated flow rate (d) 40% of rated flow rate

 Fig. 6 Stator flux trajectory at rated condition of proposed system

(a)      

                                                         (b)

(c)

Fig. 7 Performance parameters of hybrid system (a) PV parameters (S, Vdc,

Vpv, Ipv) (b) Battery indices (Vdc, SOC, Vbat, Ibat) (c) Motor indices

 

(b)

(c)

Fig. 8 Performance parameters during battery charging of hybrid system (a)

PV parameters (S, Vdc, Vpv, Ipv) (b) Battery indices (Vdc, SOC, Vbat, Ibat)

(c) Motor indices

Fig. 9 Starting performance of the drive: (a) 1000W/m2 (b) 500W/m2

CONCLUSION:

The proposed solar PV array fed water pumping system has been modeled and simulated in MATLAB/Simulink in standalone and PV array-battery connected modes, and its suitability is studied experimentally on a prototype in the laboratory. In standalone mode with PV array feeding water pump, the system comprises of one voltage sensor and one current sensor, which are sufficient for the proper operation of proposed system. Moreover, a P&O based MPPT with derating feature technique has been proposed to regulate the flow rate by controlling the PV array power, thereby enabling the user to operate the pump for any discharge and flow rate. The motordrive system performs satisfactorily during starting at various insolations, steady-state, dynamic conditions represented by changing insolation. The speed is estimated in stationary flux components by flux observer, which has been used for DC offset rejection as well as for the satisfactory operation at lower frequency. The flux and torque, are controlled separately. The direct torque control (DTC) is achieved with fixed frequency switching technique for reducing the torque ripple. The line voltages are estimated from this DC link voltage. Moreover, the reconstruction of three phase stator currents, has been successfully carried out from DC link current. In addition, a smooth changeover facility from DTC to scalar control has been provided to ensure the uninterrupted performance of the system even though the current sensor fails. The switching signals are generated by space vector modulation technique (SVM) to drive three phase VSI, which has offered less harmonics distortion (THD) in motor currents as compared with SPWM technique. Simulation results are well validated by experimental results. In the second mode, a successful implementation of bidirectional power flow between PV arraybattery connected systems has been achieved and its suitability has been checked at various conditions. Owing to the virtues of simple structure, control, cost-effectiveness, fairly good efficiency and compactness, it can be inferred that the suitability of the system can be judged by deploying it in the field.

REFERENCES:

[1] G. M. Masters, Renewable and efficient electric power systems, IEEE Press, Wiley and Sons, Inc. 2013, pp. 445-452.

[2] R. Foster, M. Ghassemi and M. Cota, Solar energy: Renewable energy and the environment, CRC Press, Taylor and Francis Group, Inc. 2010.

[3] S. Parvathy and A. Vivek, “A photovoltaic water pumping system with high efficiency and high lifetime,” Int. Conf. Advancements in Power and Energy (TAP Energy), pp.489-493, 24-26 June 2015.

[4] G. M. Shafiullah, M. T. Amanullah, A. B. M. Shawkat Ali, P. Wolfs, and M. T. Arif, Smart Grids: Opportunities, Developments and Trends. London, U.K.: Springer, 2013.

[5] Vimal Chand Sontake and Vilas R. Kalamkar, “Solar photovoltaic water pumping system – A comprehensive review,” Renewable and Sustainable Energy Reviews, vol. 59, pp. 1038-1067, June 2016.

Study On Speed Sensorless SVM-DTC System Of PMSM

ABSTRACT:
A novel speed sensorless direct torque control system-SVM-DTC of permanent magnet synchronous motor (PMSM) based on SVM and MRAS is presented. In this paper the various components of the speed sensorless SVM-DTC and the principle of realization are discussed in detail. Finally the simulation results with the application of MATLAB/SIMULINK show that the speed identification algorithm is accurate and of robustness, moreover, the whole control system has good static and dynamic performances.
KEYWORDS:
1. Permanent magnet synchronous motor (PMSM)
2. Space Vector Modulation (SVM)
3. Direct torque control (DTC)
4. Model reference adaptive system (MRAS)
SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:


Fig.1. Speed-sensor less SVM-DTC diagram.
EXPECTED SIMULATION RESULTS:


Fig.2 (a) Estimated speed curve Fig.2 (b) Actual speed curve

Fig.2 (c) Speed error curve Fig.2 (d) Torque response

Fig.2(e) A-phase stator current waveform Fig.3 (a) Estimated speed curve

Fig.3 (b) Actual speed curve Fig.3 (c) Speed error curve


Fig.3 (d) Torque response Fig.3 (e) A-phase stator current waveform
CONCLUSION:
In this paper, the speed sensorless SVM-DTC system based on SVM and MRAS is presented and the control system has a clear control principle and structure. Simulation results show that the speed identification algorithm can estimate accurately the real speed and has robustness to varying of stator resistor. Moreover the speed sensorless SVM-DTC system has good static and dynamic performance.

REFERENCES:
[1] Yen-Shin Lai, Jian-Ho Chen..A New Approach to Direct Torque Control of Induction Motor Drives for Constant Inverter Switching Frequency and Torque Ripple Reduction[J],IEEE Transactions on Energy Conversion,2001,16(3),220-227
[2] Liang yan, Li Yongdong. The state of art of sensor-less vector control of PMSM[J]. Electric Drive,2003,33(4):4-9
[3] Young Sam Kim, Sang Kyoon Kim,Young Ahn Kwon.MRAS Based Sensorless Control of Permanent Magnet Synchronous Motor[C]. SICE Annual Conference, Fukui, Japan, 2003:1632-1637
[4] Li Yongdong. AC motor digital control system [M]. Beijing: Machine Press,2002
[5] Li Su. Direct Torque Control of Induction Motor[M]. Beijing: Machine Press,1999