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.

Solar PV Array Fed Direct Torque Controlled Induction Motor Drive for Water Pumping

ABSTRACT:

 This paper deals with the solar photovoltaic (PV) array fed direct torque controlled (DTC) induction motor drive for water pumping system. To extract maximum power from the solar PV array, a DC-DC boost converter is employed. The soft starting of a three-phase induction motor is achieved by controlling the DC-DC boost converter through the incremental conductance maximum power point tracking (MPPT) technique. The induction motor is well matched to drive a type water pump due to its load characteristics. It is well suited to the MPPT of the solar PV array. By using DTC technique, an induction motor exhibits homogeneous or even better response than the DC motor drive. The proposed system is designed and its performance is simulated in MATLAB/Simulink platform. Simulated results are demonstrated to validate the design and control of the proposed system.

KEYWORDS:

  1. Solar Photovoltaic (PV)
  2. Direct Torque Control (DTC)
  3. MPPT Control
  4. Induction Motor
  5. Water Pump

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig.l Schematic diagram of proposed system configuration

EXPECTED SIMULATION RESULTS:

 Fig.2 Steady state performance of proposed system

Fig.3 Starting performance of proposed system

Fig.4 Performance of the system at decrease in insolations

Fig.5 Performance of the system at increase in insolations

CONCLUSION:

It has been demonstrated that the solar PV array fed DTC controlled induction motor drive has been found quite suitable for water pumping. A new method for reference speed generation for DTC scheme has been proposed by controlling the voltage at DC bus and pump affinity law has been used to control the speed of an induction motor. Solar PV array has been operated at maximum power during varying atmospheric conditions. This is achieved by using incremental conductance based MPPT algorithm. The speed PI controller has controlled the motor stator current and controlled the flow rate of pump. Simulation results have demonstrated that the performance of the controller has been found satisfactory under steady state as well as dynamic conditions.

REFERENCES:

[I] R. Foster, M. Ghassemi and M. Cota, Solar energy: Renewable energy and the environment, CRC Press, Taylor and francis Group, Inc. 20 I O.

[2] S. Jain, Thopukara, AK. Karampur and V.T. Somasekhar, “A SingleStage Photovoltaic System for a Dual-Inverter-Fed Open-End Winding Induction Motor Drive for Pumping Applications,” iEEE Trans. On Power Electro.. vo1.30, no.9, pp.4809-4818, Sept. 2015.

[3] M. A Razzak, A S. K. Chowdhury and K. M. A Salam, “Induction motor drive system using Push-Pull converter and three-phase SPWM inverter fed from solar photovoltaic panel,” international Conference on 2014 Power and Energy Systems: Towards Sustainable Energy, 13- 15 March 2014.

[4] J.V. Caracas Mapurunga, G. Farias Carvalho De, L. F. Moreira Teixeira, L.A Ribeiro De Souza, “Implementation of a HighEfficiency, High-Lifetime, and Low-Cost Converter for an Autonomous Photovoltaic Water Pumping System,” iEEE Trans. On ind. Appl., vo1.50, no.!, pp.631-641, Jan.-Feb. 2014.

 

FLC-Based DTC Scheme to Improve the Dynamic Performance of an IM Drive

 

ABSTRACT:

This paper presents a fuzzy logic hysteresis comparator-based direct torque control (DTC) scheme of an induction motor (IM) under varying dynamic conditions. The fuzzy logic controller (FLC) is used to adjust the bandwidth of the torque hysteresis controller in order to reduce the torque and flux ripples and, hence, to improve motor dynamic response. The effects of torque hysteresis bandwidth on the amplitude of torque ripples of an IM are also discussed in this paper. Based on the slopes of motor-estimated torque and stator current, an FLC is designed to select the optimum bandwidth of the torque hysteresis controller. This paper also proposes a simpler algorithm than the conventional trigonometric function-based algorithm to evaluate the sector number (required for DTC scheme) of the stator flux-linkage space vector. The proposed algorithm reduces the computational burden on the microprocessor. In order to test the performance of the proposed FLC-based DTC scheme for IM drive, a complete simulation model is developed using MATLAB/ Simulink. The proposed FLC-based DTC scheme is also implemented in real time using DSP board DS1104 for a prototype 1/3 hp motor. The performance of the proposed drive is tested in both simulation and experiment.

KEYWORDS:

1          Direct torque control (DTC)

2          Field-oriented control(FOC)

3          Fuzzy logic controller (FLC)

4          Induction motor (IM)

5          Torque and flux hysteresis controllers

6          Torque ripples

SOFTWARE: MATLAB/SIMULINK

CONVENTIONAL BLOCK DIAGRAM:

 Fig. 1. Conventional DTC scheme for IM drive.

SIMULATION RESULTS:

Fig. 2. Steady-state speed responses of the IM drive for a step change in load from 0.3 to 0.8 N · m at 120 rad/s. (a) Conventional DTC. (b) FLC-based DTC.

Fig. 3. Developed torque responses of the IM drive for a step change in load from 0.3 to 0.8 N · m at speed of 120 rad/s. (a) Conventional DTC. (b) FLC-based DTC scheme.

Fig. 4. Developed torque of the IM drive at 40% of rated load. The step change in speed from 100 to 150 rad/s is applied at 0.15 s. (a) Conventional DTC. (b) FLC-based DTC scheme.

Fig. 5. Steady-state stator flux-linkage responses of the IM drive, at 40% rated load and speed of 120 rad/s. (a) Conventional DTC. (b) Proposed FLCbased DTC scheme.

Fig. 6. Steady-state stator current response of the IM drive at 40% rated load and speed of 120 rad/s. (a) Conventional DTC. (b) FLC-based DTC scheme.

CONCLUSION:

A novel FLC-based DTC scheme for IM drive has been presented in this paper. The proposed FLC-based IM drive has been successfully implemented in real time using DSP board DS1104 for a laboratory 1/3 hp IM. The FLC is used to adapt the bandwidth of the torque hysteresis controller in order to reduce the torque ripple of the motor. A performance comparison of the proposed FLC-based DTC scheme with a conventional DTC scheme has also been provided both in simulation and experiment. Comparative results show that the torque ripple of the proposed drive has considerably been reduced. The dynamic speed response of the proposed FLC-based DTC scheme has also been found better as compared to the conventional DTC scheme.

REFERENCES:

[1] I. Takahashi and T. Nouguchi, “A new quick response and high efficiency control strategy for an induction motor,” IEEE Trans. Ind. Appl., vol. IA- 22, no. 5, pp. 820–827, Sep. 1986.

[2] L. Tang, L. Zhong, M. F. Rahman, and Y. Hu, “A novel direct torque control for interior permanent-magnet synchronous machine drive with low ripple in torque and flux-a speed-sensorless approach,” IEEE Trans. Ind. Appl., vol. 39, no. 6, pp. 1748–1756, Sep./Oct. 2003.

[3] S. Kouro, R. Bernal, H. Miranda, C. A. Silva, and J. Rodriguez, “Highperformance torque and flux control for multilevel inverter fed induction motors,” IEEE Trans. Power Electron., vol. 22, no. 6, pp. 2116–2123, Nov. 2007.

[4] D. Casadei and T. Angelo, “Implementation of a direct torque control algorithm for induction motors based on discrete space vector modulation,” IEEE Trans. Power Electron., vol. 15, no. 4, pp. 769–777, July 2000.

[5] C.-T. Lin and C. S. G. Lee, Neural Fuzzy Systems: A Neuro-Fuzzy Synergism to Intelligent Systems. Upper Saddle River, NJ: Prentice-Hall, 1996.

Direct Torque Control of Permanent-Magnet Synchronous Machine Drives With a Simple Duty Ratio Regulator

ABSTRACT:

The conventional switching-table-based direct torque- controlled (DTC) ac machine drive is usually afflicted by large torque ripple, as well as steady-state error of torque. The existing methods, which optimize the duty ratio of the active vector, are usually complicated and parameter dependent. Based on the analysis of instantaneous variation rates of stator flux and torque of each converter output voltage vector, a simple and effective method considering the effect of machine angular velocity is proposed to obtain the duty ratio. The experimental results carried on a dSPACE platform with a laboratory prototype of the permanent-magnet machine verify that the proposed duty-based DTC method can achieve excellent transient response, less torque ripple, and less steady-state error, without resorting to the complicated control method over a wide range of operating regions.

KEYWORDS:
1. Direct torque control (DTC)
2. Duty ratio
3. Permanent-magnet synchronous machines (PMSMs)
4. Steady-state error
5. Torque ripple

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

image001Fig. 1. Control diagram of DTC of PMSM.

EXPECTED SIMULATION RESULTS:

image002

Fig. 2. Comparison of steady-state performance of various DTC methods (rated condition: 400 r/min, 5 N • m). (a) Conventional DTC method. (b) M1. (c) M2. (d) Proposed DTC method.

image003Fig. 3. Dynamic performances of torque response with inner torque loop control only and without outer speed loop. Reference torque from 2 to −2 N • m. (a) Conventional DTC method. (b) M1. (c) M2. (d) Proposed DTC method.

image004Fig. 4. Dynamic and steady-state performances when reference speed changes from 200 to −200 r/min. (a) Conventional DTC. (b) Proposed DTC.

image005Fig. 5. Steady-state performance of the proposed DTC method with different control parameters: Ka = 0.7, Kb = 0.0005 (rated condition: 400 r/min,5 N • m).

CONCLUSION:
This paper has proposed, analyzed, and experimentally verified a simple and effective method for determining the appropriate duty ratio in DTC three-phase PMSM drives to reduce the torque ripple and the steady-state error of torque, accounting for the influence of machine angular velocity. A simple estimated method is proposed to obtain the range of the key control parameters. Compared to the existing duty-based DTC methods, the proposed method can achieve the decent performance of torque and flux at the lower price of increased average communication frequency.
The proposed duty ratio determination has the following features.
1) Simple structure: Compared to conventional DTC, just a very simple duty ratio regulator is added.
2) Parameter independent: Unlike the previous duty-based methods, where many parameters such as stator inductance and PM flux are required, in the proposed DTC method, only the torque error and speed are needed to compute the duty ratio, which makes it robust to parameter variation.
3) Outstanding steady-state performance over a wide range of operating regions, even when speed is reversed.
4) Similar excellent transient response to the conventional DTC.
Although the analysis and experiments in this paper are based on the DTC of three-phase PMSM drives, the proposed duty ratio determination can be also extended for general use and applied to the other machines of switching-table-based direct torque and power control methods, which may exhibit the same problem of ripple and/or steady-state error.

REFERENCES:
[1] I. Takahashi and T. Noguchi, “A new quick-response and high-efficiency control method of an induction-motor,” IEEE Trans. Ind. Appl., vol. IA-22, no. 5, pp. 820–827, Sep. 1986.
[2] M. Depenbrock, “Direct self-control (DSC) of inverter-fed induction machine,” IEEE Trans. Power Electron., vol. 3, no. 4, pp. 420–429, Oct. 1988.
[3] G.W. Chang, G. Espinosa-Perez, E. Mendes, and R. Ortega, “Tuning rules for the PI gains of field-oriented controllers of induction motors,” IEEE Trans. Ind. Electron., vol. 47, no. 3, pp. 592–602, Jun. 2000.
[4] A. K. Jain and V. T. Ranganathan, “Modeling and field oriented control of salient pole wound field synchronous machine in stator flux coordinates,” IEEE Trans. Ind. Electron., vol. 58, no. 3, pp. 960–970, Mar. 2011.
[5] S. Mathapati and J. Boecker, “Analytical and offline approach to select optimal hysteresis bands of DTC for PMSM,” IEEE Trans. Ind. Electron., vol. 60, no. 3, pp. 885–895, Mar. 2013.