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.

 

Solar Powered Based Water Pumping System Using Perturb and Observation MPPT Technique

ABSTRACT:

This paper concentrates on solar photovoltaic(PV) water pumping system using perturb and observation maximum power point tracking(MPPT) technique. This whole system is divided into two stages. In the first stage, an arrangement of PV modules is made which is a combination of number PV cells in series or parallel to extract the solar energy and convert into electricity. To maximize the power output of PV module, perturb and observation (P&O) MPPT technique has been used. In its second stage, direct torque and flux control(DTFC) with space vector modulation(SVM) is used to control switching pulses of the voltage source inverter(VSI). The speed of induction motor drive is controlled by DTFC technique. The whole system is developed in MATLAB and outputs are observed.

 KEYWORDS:

  1. Solar PV array
  2. MPPT
  3. P&O Algorithm
  4. DC-DC Boost converter
  5. DTFC-SVM
  6. Induction motor

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 Fig-1: Solar Water Pumping System

EXPECTED SIMULATION RESULTS:

Fig. 2. DC link voltage (output voltage of the boost converter)

Fig. 3. output waveform of IMD under no load

Fig. 4. Waveforms under loading condition

CONCLUSION:

In this paper control methods which regulates the flow rate of water supply of solar powered based water pumping systen using IMD is illustrated. From the simulation results it can be concluded that this system has good performance. As per view of irrigation system , the SPV array has been operated under standard enviromental conditions. The system is operated on maximum power by using P&O MPPT algorithm. Water flow rate and stator current of motor is controlled by the speed PI controller.

 REFERENCES:

 [1] U. Sharma, S. Kumar, and B. Singh, “Solar array fed water pumping system using induction motor drive,” 1st IEEE Int. Conf. Power Electron. Intell. Control Energy Syst. ICPEICES 2016, 2017.

[2] M. A. G. De Brito, L. P. Sampaio, L. G. Jr, G. A. Melo, and C. A. Canesin, “Comparative Analysis of MPPT Techniques for PV Applications,” pp. 99–104, 2011.

[3] D. P. Hohm, “Comparative Study of Maximum Power Point Tracking Algorithms Using an Experimental, Programmable, Maximum Power Point Tracking Test Bed,” 2000.

[4] S. Member, “A Comparative study of different MPPT techniques using different dc-dc converters in a standalone PV system,” pp. 1690–1695, 2016.

[5] Z. Ben Mahmoud, M. Ramouda, and A. Khedher, “A Comparative Study of Four Widely-Adopted MPPT Techniques for PV Power Systems,” no. 1, pp. 16–18, 2016.

Control of Induction Motor Drive using Space Vector PWM

ABSTRACT:  

In this paper speed of acceptance engine is controlled, supply from three stage connect transformer because the variety in information Voltage or recurrence in turn both changes the speed of an taking in engine. Variable voltage and recurrence for Adjustable Speed Drives (AS D) is constantly acquires from a three-stage Voltage Source Invert er (V SI) also P WM strategies controls the Voltage and recurrence of transform er, so which is an imperative viewpoint in the use of AS D s.

P WM Techniques

A number of P WM techniques are there to obtain variable voltage and frequency supply such as P WM, SP WM, S VP WM and among the various modulation strategies, SVPWM is one of the most efficient techniques as it has better performance and output voltage is similar to sinusoidal. SVPWM the modulation index in linear region will also be high when compared to other.

 BLOCK DIAGRAM:

 Figure 1: AS D Block Diagram

 EXPECTED SIMULATION RESULTS:

 Figure 2: SP WM Pulses

Figure 3: Invert er o/p line voltages

Figure 4: Motor Speed and Electromagnetic torque.

Figure 5: SVPWM output gate pulses

                  Figure 6:Open Loop Drive Speed response with TL=0

Figure 7: Open Loop Drive Speed response with different TL

Figure 8: Sinusoidal PWM based open loop drive Load Current T H D

 CONCLUSION:

MAT LAB/Sim u link is used to carryout the simulation of “Control of Induction Motor Drive Using Space Vector P WM” for open loop as well as closed control by which the appropriate output results are obtained. The variation of speed of Induction Motor is observed by varying the load torque in open loop control and the table gives the results. Also observed that for the change in input speed commands the motor speed is settled down to its final value within 0.1 sec in closed loop model.

REFERENCES:

[1] Ab d e l fat ah K o l l i, Student Member, IEEE, Olivier Be t ho u x, Member, IEEE, A l e x a n d re D e Be r n a  r d in i s, Member, IEEE, Eric Lab our e, and G e r a rd Co q u e r y “Space-Vector P WM Control Synthesis for an H-Bridge Drive in Electric Vehicles” IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 62, NO. 6, JULY 2013. pp. 2241-2252.

[2]Mr. Sand e e p N Pan ch a l, Mr. Vi s h a l S She t h, Mr. A k s hay A P and ya “Simulation Analysis of S V P WM Invert er Fed Induction Motor Drives” International Journal of Emerging Trends in Electrical and Electronics (IJET E  E) Vol. 2, Issue. 4, April-2013. pp. 18-22 .

[3]H a o ran S hi, Wei X  u, Chen  g h u a F u and Y a o Yang. “Research on Three phase Voltage Type P  WM Rectifier System Based on S V P WM Control” Research Journal of Applied Sciences, Engineering and Technology 5(12): 3364-3371, 2013. pp. 3364-3371.

Space Vector Pulse Width Modulation Fed Direct Torque Control Of Induction Motor Drive Using Matlab-Simulink

ABSTRACT:

Now a day’s induction motor drives are highly demanding to design both mechanical and electrical drive system which is used widely in many industrial applications. Recent years many mathematical models for induction motor drive using Simulink models are employed. Scalar and Vector control method can be applied to induction motors in three phases symmetric as well as unsymmetrical two-phase form. The mathematical and Simulink operation of the induction motor drive can be studied and it is equivalent to a DC motor by the vector control method. With the combined performance of the numerical electronics and power electronics we are capable to smoothly control the variable speed and torque in low power industrial operations. With the help of technological achievements, several command and control techniques are developed by the technologists to control the time, flux and torque of the industrial electrical machine drives. The direct torque control (DTC) technique is one of the most advanced mechanisms in control operation of torque and speed. This technique with SVPWM gives fine regulation without rotational speed controlled feedback. The electromagnetic torque and stator flux are estimated in DTC technique only stator currents and voltage and it is independent of the parameters of the motor except for the Rs i.e. stator resistance [7].

KEYWORDS:

  1. Controller
  2. DTC
  3. IDM
  4. SVPWM and switching table.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig.1. DTC block diagram

EXPECTED SIMULATION RESULTS:

 

Fig.2. Electromagnetic torque

Fig.3. Rotor speed

Fig.4. Stator current

Fig.5. d-axis stator flux

Fig.6. q-axis stator flux

Fig.7. Electromagnetic torque

Fig.8. Rotor speed

Fig.9. Trajectory of direct axis stator and quadrature axis

flux (stationary reference frame)

Fig.10. Electromagnetic torque

Fig.11. Rotor speed

Fig.12. Direct axis stator flux

Fig.13. Quadrature axis stator flux

Fig.14. Direct axis stator current

Fig.15. Quadrature axis stator current

Fig.16. Stator flux trajectory

Fig.17. Rotor flux trajectory

CONCLUSION:

The proposed paper highlights to create a Simulink model of  DTC in induction motor drive. The DTC technique allows the decoupled control of torque and stator flux operate indipendently. The control process is simulated with the help of simpower system MATLAB Simulink block set and Sector determination with open-loop induction motor drive is obtained. In conventional DTC technique, high torque ripple is produced because the voltage space vector which are considered is applied for the whole switching period without considering the torque error value. This torque ripple can be minimized in order to achieve a smooth operation of the drive system and its performances, by changing the duty cycle ratio of the voltage vector which are selected during each switching cycle period, based on the stator flux position and torque error magnitude. This constitutes the basic of SVPWM technique. here simulate DTC scheme based on SVPWM technique and comparative study of conventional DTC-SVM scheme is derived and studied.

REFERENCES:

[1] Takahashi Isao, Noguchi Toshihiko, ,,’’A New Quick-Response IEEE Transactions on Industry Applications , Vol. IA-22No-5, Sept/Oct 1986.

 

Power Electronics IEEE Projects 2017-2018

power electronics ieeePower electronics ieee

power electronics ieee is the application of solid-state electronics to the control and conversion of electric power.

The first high power electronic devices were mercury-arc valves. In modern systems the conversion is performed with semiconductor switching devices such as diodesthyristors and transistors, pioneered by R. D. Middlebrook and others beginning in the 1950s. In contrast to electronic systems concerned with transmission and processing of signals and data, in power electronics substantial amounts of electrical energy are processed. An AC/DC converter (rectifier) is the most typical power electronics device found in many consumer electronic devices, e.g. television sets, personal computersbattery chargers, etc. The power range is typically from tens of watts to several hundred watts. In industry a common application is the variable speed drive (VSD)that is used to control an induction motor. The power range of VSDs start from a few hundred watts and end at tens of megawatts.

The power conversion systems can be classified according to the type of the input and output power

energy renewable

Fuzzy Efficiency Enhancement of Induction Motor Drive

 

ABSTRACT:

Efficiency improvement of motor drives is important not only from the viewpoints of energy loss and hence cost saving, but also from the perspective of environmental pollution. Several efficiency optimization methods for induction motor (IM) drives have been introduced nowadays by researchers. Distinctively, artificial intelligence (AI)-based techniques, in particular Fuzzy Logic (FL) one, have been emerged as a powerful complement to conventional methods. Design objectives that are mathematically hard to express can be incorporated into a Fuzzy Logic Controller (FLC) using simple linguistic terms. The merit of FLC relies on its ability to express the amount of ambiguity in human reasoning. When the mathematical model of a process does not exist or exists with uncertainties, FLC has proven to be one of the best alternatives to move with unknown process. Even when the process model is well-known, there may still be parameter variation issues and power electronic systems, which are known to be often approximately defined. The purpose of this paper is to demonstrate that a great efficiency improvement of motor drive can be achieved and hence a significant amount of energy can be saved by adjusting the flux level according to the applied load of an induction motor by using an on-line fuzzy logic optimization controller based on a vector control scheme. An extensive simulation results highlight and confirm the efficiency improvement with the proposed algorithm.

KEYWORDS:

  1. Induction Motor Drive
  2. Indirect Field Oriented Control (IFOC)
  3. Efficiency Enhancement
  4. Losses Minimization
  5. Optimization
  6. Fuzzy Logic

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig.1. Block diagram of the optimization system

 EXPECTED SIMULATION RESULTS:

Fig.2. Motor Performances Comparison

Fig.3. Motor efficiency evolution with motor load

 CONCLUSION:

This paper aims to improve the induction motor drive efficiency that leads to a significant amount of energy saving. This efficiency enhancement is carried out by adjusting the flux level depending on the applied load of an induction motor by using an on-line fuzzy logic optimization controller based on a vector control scheme. A series of the induction motor drive performances are obtained with a variable load under this proposed algorithm. The application of the proposed algorithm yields to a series of simulation performances of the induction motor drive with a variable load. They present the IM drive efficiency evolution with a certain load profile with the suggested losses minimization strategy based on fuzzy control and the conventional field oriented control. The comparison between these two control schemes reveals that the achieved results are of a great interest. Indeed, the fuzzy control contributes with a great deal to the efficiency improvement for all operating speeds particularly in light load region. This contribution conducts to a paramount energy saving and hence to environment protection.

REFERENCES:

[1] I. Boldea, A. Nasser, The Induction Machine Design Handbook, CRC Press Inc; 2nd Revised Edition, 2009.

[2] Jinchuan. Li and all, “A new Optimization Method on Vector Control of Induction Motors”, Electric Machines and Drives, 2005 IEEE International Conference, 15-18 May 2005, pp.1995-2001.

[3] H. Sepahv and, Sh. Ferhangi, “Enhancing Performance of a Fuzzy Efficiency Optimizer for Induction Motor Drives”, Power Electronics Specialists Conference, 2006. PESC ’06. 37th IEEE, 18-22 June.2006, pp.1-5.

[4] Branko Blanusa and all, “An Improved Search Based Algorithm for Efficiency Optimization in the Induction Motor Drives”, XLII Konferencija- za ETRAN, Hercy-Novi, 2003.

[5] D. S. Kirischen, D. W. Novoty and T. A. Lipo, “Optimal Efficiency Control of an Induction Motor Drive”, IEEE Transaction on Energy Conversion, Vol. EC-2, N° 1, March 1987, pp.70-76.

Direct torque control of squirrel cage induction motor for optimum current ripple using three level inverter

ABSTRACT:

Control of induction motor is most precisely required in many high performance applications. With the development in power electronic field various control methods for control of induction motor have been developed. Among these Direct torque control (DTC) seems to be particularly interesting, being independent of machine rotor parameters and requiring no speed or position sensors. In addition to the simple structure it also allows a good torque control in transient and steady state conditions. The disadvantage of using DTC is that it results in high torque and flux ripple and variable switching frequency of voltage source inverter, owing to the use of hysteresis controllers for torque and flux loop. In order to overcome these problems, various methods have been proposed by several researchers like variable hysteresis band comparators, space vector modulation, predictive control schemes and intelligent control techniques. However these methods have diminished the main feature of DTC that is simple control structure. This report presents constant switching frequency based torque and flux controllers to replace conventional hysteresis based controllers where almost fixed switching frequency with reduced torque and flux ripple is obtained by comparing the triangular waveforms with the compensated error signals

KEYWORDS:

1.3-phase VSI
2. Torque controller
3. Flux controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:


Fig.1. Block diagram of conventional DTC method


Fig.2. MATLAB/SIMULINK Model of the DTC Drive

Fig.3. Torque response (a) Conventional DTC scheme (b) Improved DTC Scheme


Fig.4. Speed and Torque response for (a) Conventional DTC scheme (b) Improved DTC scheme

Fig.5. Circular flux locus (a) conventional DTC scheme (b) Improved DTC scheme


Fig.6. 3-phase line-line voltages and currents (a) Conventional DTC scheme (b) Improved DTC scheme

CONCLUSION:

In this paper a detailed comparison between the conventional DTC and improved DTC scheme is made with help of some Matlab simulation results and hence it is shown that a significant reduction in torque and flux ripple can be achieved with the improved DTC scheme also with improved controllers the switching frequency which is constant can be varied by varying the frequency of the triangular carrier waveforms of the torque controller

REFERENCES:

  1. Takahashi and T. Noguchi, “A new quick-response and high efficiency control strategy of an induction motor,” IEEE Trans. Ind. Appl., vol. IA-22,no. 5, pp. 820–827, Sep.–Oct. 1986. [2] J-K. Kang, D-W Chung, S. K. Sul, (2001) “Analysis and prediction of inverter switching frequency in direct torque control of induction machine based on hysteresis bands and machine parameters”, IEEE Transactions on Industrial Electronics, Vol. 48, No. 3, pp. 545-553.
  2. Casadei, G.Gandi,G.Serra,A.Tani,(1994)“Switching strategies in direct torque control of induction machines,in Proc. of ICEM’94, Paris (F), pp. 204-209.
  3. J-K. Kang, D-W Chung and S.K. Sul, (1999) “Direct torque control of induction machine with variable amplitude control of flux and torque hysteresis bands”, International Conference on electric Machines and Drives IEMD’99,pp.640-642.
  4. Vanja Ambrozic, Giuseppe S. Buja, and Roberto Menis, ”Band- Constrained Technique for Direct Torque Control of Induction Motor”, IEEE Trans. On industrial electronics , vol. 51, no. 4, august 2004, pp.776-784

Analysis of Performance of the Induction Motor under Hysteresis Current Controlled DTC

ABSTRACT:

The direct torque control method is a powerful control technique for specially induction motor drive due its fast dynamic torque response. It originates in the fact that torque and flux is directly controlled by instantaneous space voltage vector unlike. Field Oriented Control (FOC) and smooth control of drives are being utilized to perform real time simulation on the ac motor variables, such as electromagnetic torque, fluxes, mechanical speed, etc. For the reason, direct torque control gradually has been used in the field requiring fast response since its introduction in the mid-1980. Even though the direct torque control has several problems. These problems are: (I) low switching frequency and variation in speed; (2) the increase of the torque ripple in the low speed region; (3) the short control period (25 /ls) for the good performance. To solve the problems of Direct Torque Control, several studies were carried out. This paper improves one of the drawbacks of Direct Torque Control with the Hysteresis direct torque control. In some papers to avoid these problems 2 level inverter with induction motor has been used but it is very complicated and didn’t show large improvement. In this paper, Hysteresis direct torque control method with 3 level inverter has been implemented and its effectiveness is compared with conventional direct torque control with 2 level inverter by using Matlab/Simulink.

KEYWORDS:

  1. Direct Torque Control
  2. Hysteresis Direct Torque Control
  3. Two Level Inverter
  4. Three Level Inverter.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Basic DTC Scheme

Induction Motor Hysteresis Current Controlled DTC

SIMULINK BLOCK DIAGRAM:

Simulink model of the direct torque controlled induction motor with Conventional DTC.

Induction Motor Hysteresis Current Controlled DTC

Simulated two level phase voltage s of Inverter with Conventional DTC and Simulated output wave form of the Id, Iq currents Drawns from Induction motor with conventional DTC

Induction Motor Hysteresis Current Controlled DTC

Fig.5. Simulated output wave form of the Reference and Simulated output wave form of the and actual speeds of the Induction Reference and actual Torque of the motor with conventional DTC Induction motor with conventional DTC

Induction Motor Hysteresis Current Controlled DTC

Simulated XY plot wave form of .Simulated phase voltages of inverter with flux current with conventional DTC. Hysteresis current controlled DTC

Induction Motor Hysteresis Current Controlled DTC

Simulated XY plot wave form of flux current with Hysteresis current controlled DTC

Induction Motor Hysteresis Current Controlled DTC

CONCLUSION:

In the present work initially the modeling and simulation of a three phase three level synchronous link converter using hysteresis controller and adaptive hysteresis controller is presented. The hysteresis controller for the 3 level converters is designed and developed in the Simulink model. The modeling, simulation of a direct torque and direct flux control of an induction motor fed from a three phase three level inverter is presented in this paper. The effectiveness of the proposed 3 level inverter fed induction motor drive controlled with hysteresis current controlled DTC is compared with 2 level inverter fed induction motor drive with conventional DTC and it is observed in simulation results the improvement in low speed operation performance of induction motor for high power three level inverter applications.

REFERENCES:

[I] Rakesh Kantaria and S.K.Joshi “A review on power quality problems and solutions” Power electronics National Conference November 2008.

[2]IEEE Std. 1159 – 1995, “Recommended Practice for Monitoringn Electric Power Quality.

[3]Yan Li, Chengxiong Mao, Buhan Zhang, Jie Zeng, “Voltage Sag Study for a Practical Industrial Distribution Network”, 2006 International Conference on Power System Technology, pp.I-4, Oct., 2006.

[4]Understanding FACTS: Concepts and Technology of Flexible AC Transmission Systems. Narain G. Hingorani, Laszlo Gyugyi. Wiley IEEE press.

[5] J. G. Nielsen, M. Newman, H. Nielsen, and F. Blaabjerg, “Control and testing of a dynamic voltage restorer (DVR) at medium voltage level,”iEEE Trans. Power Electron., vol. 19, no. 3,p.806,May 2004

 

 

Direct Torque Control of Induction Motor With Constant Switching Frequency

ABSTRACT

Direct Torque Control (DTC) has become a popular technique for the control of induction motor drives as it provides a fast dynamic torque response and robustness to machine parameter variations. Hysteresis band control is the one of the simplest and most popular technique used in DTC of induction motor drives. However the conventional direct torque control has a variable switching frequency which causes serious problems in DTC. This paper presents the DTC of induction motor with a constant switching frequency torque controller. By this method constant switching frequency operation can be achieved for the inverter. Also the torque and flux ripple will get reduced by this technique. The feasibility of this method in minimizing the torque ripple is verified through some simulation results.

 

KEYWORDS

  1. Direct torque control(DTC)
  2. Constant switching frequency
  3. Induction motor
  4. Three phase inverter.

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig. 1. Block diagram of conventional DTC

 

EXPECTED SIMULATION RESULTS

Fig. 2. Step response of torque (a) hysteresis based (b) modified torque controller

Fig. 3. Response of torque and speed for squre wave torque reference in (a) hysteresis based (b)modified torque controller

Fig. 4.(a) Hysteresis based controller (b) modified torque controller

Fig. 5. flux waveform for (a) hysteresis based (b)modified torque controller

Fig. 6. flux locus for (a) hysteresis based (b)modified torque controller

Fig. 7. Frequency spectrum of the switching pattern Sb for (a) hysteresis based (b) modified torque controller

 

CONCLUSION

This paper presents a constant switching frequency torque controller based DTC of induction motor drive. By using the modified torque controller the switching frequency of the inverter also becomes constant at 10 kHz. As a result, the harmonic contents in the phase currents are very much reduced. So the phase current distortion is reduced. The torque ripple is also reduced by replacing the torque hysteresis controller with the modified torque controller. Moreover, with the modified torque controller, an almost circular stator flux locus is obtained. Without sacrificing the dynamic performance of the hysteresis controller, the modified scheme gives constant switching frequency. This work can be implemented using DSP. The work can be extended by increasing the switching frequency above audible range, i.e. more or equal to 20 kHz. This is an effective way to shift the PWM harmonics out of human audible frequency range. With high switching frequency the harmonic content of stator current will be reduced significantly.

 

REFERENCES

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