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.

 

Efficiency Optimization of Induction Motor Drive at Steady-State Condition

 

ABSTRACT:

Induction motors are workhorse of industries due to its power/mass relation, efficiency, low cost and nearly maintenance free operation in its life cycle. However motors with low efficiency waste a lot of energy that will increase its operational cost. As a result of high energy consumption and the huge number of operating units, even a small increase in efficiency improvement has significant effect on the entire energy consumptions and operational cost. This paper uses key features of loss model control (LMC) and search control (SC) together for estimation and reproduction of optimal flux component of current (Ids), for optimal efficiency operation of induction motor. At first, a d-q loss model of induction motor is used to derive a loss-minimization expression considering core saturation. The loss expression is used to derive optimal Ids expression and then Ids is estimated for various load profiles and finally tabulated. Based on those tabulated values, a look-up table in MATLAB is designed, and thus optimal Ids* value can be reproduced, depending upon run-time load profile, in feed-forward manner, and thus eliminates run-time loss model complex computation. Efficiency is compared for conventional vector control (constant Ids) and proposed optimal control (optimal Ids) operations. Superior efficiency performance (1-18%) is observed in optimal flux operation at steady-state, for load torque above 60% in simulation, for wide range of speed. The proposed hybrid concept is easy to implement, run-time computation free operation, ripple free operation, and offers higher power saving ratio with respect to useful output power.

KEYWORDS:

  1. Induction motor drive
  2. Efficiency optimization
  3. Vector control
  4. Optimal control
  5. Look-up table

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1(a). MATLAB model for efficiency validation

EXPECTED SIMULATION RESULTS:

Fig. 2. Speed, Torque and Efficiency perfonnance at (a) at rated load torque (200N-m) at 120 radis speed, 12% efficiency rise, (b) at 3/4th rated load torque (150Nm) at 120 radis speed, 5% efficiency rise

Fig.3 Ids* values at different speeds

Fig. 4(a) Efliciency- vs- Load-Torque at 120 radis, (b) Efliciency- vs- Speed

Fig. 5(a) Input Power- vs- Speed, (b) %age power saving- vs- speed

CONCLUSION:

In this work, it is verified that the optimal flux operation is superior to that of vector control method under steady – state condition, in terms of efficiency enhancement and hence energy-saving. In general I – 18% improvement is observed on 50 HP, 60 Hz motor, at different load-torques (above 60%) and speeds, in simulink environment. Efficiency improvement margin is seen degraded below 60% of rated load, and conventional vector control performs better. This can be seen as shortcoming of proposed method. The dynamic performance is seen satisfactory (similar to vector control), but speed and torque tracking accuracy is degraded a bit, but still the proposed approach is extremely suitable for such an application where maintaining speed and torque very precisely is not a critical issue, such as an induction motor drive used in an industrial HV AC applications. A lot of electricity can be saved with this minute compromise in speed and torque, since it offers higher amount of energy savings as compared to existing methods, hence a great contribution towards social and environmental aspects. The proposed method can be easily implemented on other induction motor drive systems also, for which the steady-state speed-vs.-torque load characteristics are already known or can be predicted. Also, the proposed hybrid approach eliminates the need of runtime computation complexity in traditional loss model controller (LMC), so less hardware installations required in implementation, hence cost-effective. Also, since no runtime perturbations happening as it usually happen in conventional search control (SC), so no torque ripples, hence less wear and tear of induction motor drive.

REFERENCES:

[1] A. H. M. Yatim and W. M. Utomo, “To develop an efficient variable speed compressor motor system,” universiti teknologi Malaysia (UTM), Skudai, Malasia, 2007.

[2] R. Hanitsch, “Energy efficienct electric motors,” university of technology berlin, germany, 2000.

[3] Y. Yakhelet: “Energy efficiency optimization of induction motors,” Boumerdes University, Boumerdes, Algeria, 2007.

[4] M. W. Turner, V. E. McCormick and 1. G. Cleland, Efficiency optimization control of AC induction motors: Initial laboratory results, United States Environmental Protection Agency, Research and Development, National Risk Management Research Laboratory, 1996.

[5] T. Fletier, W. Eichhammer and 1. Schleich, “Energy efficiency in electric motor systems: Technical potentials and policy approacehs fir developing countries,” United Nations Industrila Development, Vienna,2011.

 

Efficiency Optimization of Induction Motor Drive in Steady- State using Artificial Neural Network

 

ABSTRACT:

Induction motors have good efficiency at rated conditions, but at partial loads if operated with rated flux, they show poor efficiency, Motors in such conditions waste a lot of electricity, results in increased operational cost, hence significant loss of revenue, if run for long duration, Because of robustness, good power/mass relation, low cost and easy maintenance throughout its life cycle, induction motors, particularly squirrelcage induction motors are vastly used in industries. Because of the huge number of operational units worldwide, they consume a considerable amount of electrical energy, so even a minute efficiency improvement may lead to significant contributions in global electricity consumption, revenue saving and other environmental aspects. This paper uses key concepts of loss model control (LMC) and search control (SC) together for efficient operation of induction motors used in various industrial applications, where aforesaid load conditions may occur for prolonged durations. Based on the induction motor loss model in d-q frame, and using classical optimization techniques, done earlier, an optimal Ids expression in terms of machine parameters and load parameters is used to estimate optimal Ids values for various load conditions, offline, and finally tabulated. Based on which, an artificial neural network (ANN) controller is designed, taking torque and speed as input and Ids as output. The ANN controller reproduces the optimal Ids * value, as per load conditions, in feed-forward manner, and thus eliminates run-time computations and perturbations for optimal flux. The ANN training is performed in MA TLAB and the results have shown the superb accuracy of the model. Dynamic and steady-state performances are compared for conventional vector control (constant Ids) and proposed optimal control (optimal Ids) operations. Excellent dynamic as well as superior efficiency performance (1-18%) at steady- state, is observed in optimal flux operation, for load torque above 60% of rated, in simulation, for a wide range of speed, by the proposed method. Also, the method is easy to implement for real – time industrial facilities, fast response, ripple free operations, and offers higher energy savings ratio as compared to useful output power, in comparison with similar works done earlier.

KEYWORDS

  1. Energy-efficiency
  2. Induction motor drive
  3. Vector control
  4. Optimal control
  5. Efficiency optimization
  6. ANN

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1(a). MATLAB model for efficiency validation, (b) Id,* values at different speeds

EXPECTED SIMULATION RESULTS:

 

 

Fig. 2(a) Efficiency- vs- Load-Torque at 120 rad/s, (b) %age Power saving – vs- Speed

Fig. 3. Speed, Torque, Input power and Efficiency performance at for a load cycle of (150 N -m, 120 radls) for 4 sec, (200 N -m, 150 rad/s) for 3 sec, and (150 Nm, 90 rad/s) for 3 sec.

Fig. 4. Switching state performances at sample 120 rad/sec speed at a load cycle of 16 seconds.

CONCLUSION:

In this work, it is verified that the optimal flux operation is superior to that of vector control method under steady – state condition, in terms of efficiency enhancement and hence energy-saving. In general 1 – 18% efficiency improvement is observed on 50 HP, 60 Hz motor, at different load-torques (above 60%) and speeds, in Simulink environment. Efficiency improvement margin is seen degraded below 60% of rated load, and conventional vector control performs better. This can be seen as shortcoming of proposed method. The dynamic performance is seen satisfactory, similar to vector control or even better, in terms of overshoot, undershoot and settling time, speed and torque tracking accuracy is little bit deviated, but still the proposed approach is extremely suitable for such an application where maintaining speed and torque very precisely is not a critical issue, such as an induction motor drive used in an industrial HV AC applications [7, Bose 2004]. A lot of electricity can be saved with this minute compromise in speed and torque accuracy, since it offers higher amount of energy savings as compared to existing methods, hence a great contribution towards social and environmental aspects. The proposed method can be easily implemented on other induction motor drive systems also, for which the steady-state speed-vs.torque load characteristics are already known or can be predicted. The offline optimization as done here, is a limitation, as the optimal flux trajectories are only valid for one specific application, can also be considered as drawback. But, the proposed hybrid approach eliminates the need of run-time computation complexity in traditional loss model controller (LMC), so less hardware installations required in implementation, hence cost-effective. Also, since no run-time perturbations happening as it usually happen in conventional search control (SC), so no torque ripples, hence less wear and tear of induction motor drive.

REFERENCES:

[1] A. H. M. Yatim and W. M. Utomo, “To develop an efficient variable speed compressor motor system,” Universiti Teknologi Malaysia (UTM), Skudai, Malaysia, 2007.

[2] R. Hanitsch, “Energy efficient electric motors,” University of Technology, Berlin, Germany, 2000.

[3] Y. Yakhelef, “Energy efficiency optimization of induction motors,” Boumerdes University, Boumerdes, Algeria, 2007.

[4] M. W. Turner, V. E. McCormick and J. G. Cleland, Efficiency optimization control of AC induction motors: Initial laboratory results, United States Environmental Protection Agency, Research and Development, National Risk Management Research Laboratory, 1996.

[5] T. Fletier, W. Eichhammer and 1. Schleich, “Energy efficiency in electric motor systems: Technical potentials and policy approaches for developing countries,” United Nations Industrial Development, Vienna, 2011.

Efficiency Optimization of Induction Motor Drive at Steady-State Condition

ABSTRACT:

Induction motors are workhorse of industries due to its power/mass relation, efficiency, low cost and nearly maintenance free operation in its life cycle. However motors with low efficiency waste a lot of energy that will increase its operational cost. As a result of high energy consumption and the huge number of operating units, even a small increase in efficiency improvement has significant effect on the entire energy consumptions and operational cost. This paper uses key features ofloss model control (LMC) and search control (SC) together for estimation and reproduction of optimal flux component of current (Ids), for optimal efficiency operation of induction motor. At first, a d-q loss model of induction motor is used to derive a loss-minimization expression considering core saturation. The loss expression is used to derive optimalIds expression and then Ids is estimated for various load profiles and finally tabulated. Based on those tabulated values, a look-up table in MATLAB is designed, and thus optimal Ids* value can be reproduced, depending upon run-time load profile, in feed-forward manner, and thus eliminates run-time loss model complex computation. Efficiency is compared for conventional vector control (constant Ids) and proposed optimal control (optimal Ids) operations. Superior efficiency performance (1-18%) is observed in optimal flux operation at steady-state, for load torque above 60% in simulation, for wide range of speed. The proposed hybrid concept is easy to implement, run-time computation free operation, ripple free operation, and offers higher power saving ratio with respect to useful output power.
KEYWORDS:
1. Induction motor drive
2. Efficiency optimization
3. Vector control
4. Optimal control
5. Look-up table

SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:

Fig.1. MATLAB model for efficiency validation

EXPECTED SIMULATION RESULTS:


Fig. 2. Speed, Torque and Efficiency perfonnance at (a) at rated load torque (200N-m) at 120 radis speed, 12% efficiency rise, (b) at 3/4th rated load torque (150Nm) at 120 radis speed, 5% efficiency rise

Fig 3. Ids* values at different speeds

Fig. 4 Efficiency- vs- Load-Torque at 120 radis, (b) Efliciency- vs- Speed

Fig. 5 Input Power- vs- Speed, (b) %age power saving- vs- speed

CONCLUSION:
In this work, it is verified that the optimal flux operation is superior to that of vector control method under steady – state condition, in terms of efficiency enhancement and hence energy-saving. In general I – 18% improvement is observed on 50 HP, 60 Hz motor, at different load-torques (above 60%) and speeds, in simulink environment. Efficiency improvement margin is seen degraded below 60% of rated load, and conventional vector control performs better. This can be seen as shortcoming of proposed method. The dynamic performance is seen satisfactory (similar to vector control), but speed and torque tracking accuracy is degraded a bit, but still the proposed approach is extremely suitable for such an application where maintaining speed and torque very precisely is not a critical issue, such as an induction motor drive used in an industrial HV AC applications. A lot of electricity can be saved with this minute compromise in speed and torque, since it offers higher amount of energy savings as compared to existing methods, hence a great contribution towards social and environmental aspects. The proposed method can be easily implemented on other induction motor drive systems also, for which the steady-state speed-vs.-torque load characteristics are already known or can be predicted. Also, the proposed hybrid approach eliminates the need of runtime computation complexity in traditional loss model controller (LMC), so less hardware installations required in implementation, hence cost-effective. Also, since no runtime perturbations happening as it usually happen in conventional search control (SC), so no torque ripples, hence less wear and tear of induction motor drive.

REFERENCES:

[I] A. H. M. Yatim and W. M. Utomo, “To develop an efficient variable speed compressor motor system,” universiti teknologi Malaysia (UTM), Skudai, Malasia, 2007.
[2] R. Hanitsch, “Energy efficienct electric motors,” university of technology berlin, germany, 2000.
[3] Y. Yakhelet: “Energy efficiency optimization of induction motors,” Boumerdes University, Boumerdes, Algeria, 2007.
[4] M. W. Turner, V. E. McCormick and 1. G. Cleland, Efficiency optimization control of AC induction motors: Initial laboratory results, United States Environmental Protection Agency, Research and Development, National Risk Management Research Laboratory, 1996.
[5] T. Fletier, W. Eichhammer and 1. Schleich, “Energy efficiency in electric motor systems: Technical potentials and policy approacehs fir developing countries,” United Nations Industrila Development, Vienna,2011.

Dynamic Behavior of DFIG Wind Turbine Under Grid Fault Conditions

 

ABSTRACT:

The use of doubly fed induction generators (DFIGs) in wind turbines has become quite common over the last few years. These machines provide variable speed and are driven with a power converter which is sized for a small percentage of the turbine-rated power. This paper presents a detailed model of induction generator coupled to wind turbine system. Modeling and simulation of induction machine using vector control computing technique is done. DFIG wind turbine is an integrated part of distributed generation system. Therefore, any abnormalities associates with grid are going to affect the system performance considerably. Taking this into account, the performance of DFIG variable speed wind turbine under network fault is studied using simulation developed in MATLAB/SIMULINK.

KEYWORDS

  1. DFIG
  2. DQ Model
  3. Vector Control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Simulink model of DFIG system

EXPECTED SIMULATION RESULTS:

 Time (sec)

 Fig. 2 Stator currents during balance condition

Time (sec)

Fig. 3 Rotor currents during balance condition

   Time (sec)

Fig. 4 Speed and torque during balance condition.

Time (sec)

Fig. 5 Acive and reactive power during balance condition

CONCLUSION:

This paper presents a study of the dynamic performance of variable speed DFIG coupled with wind turbine. The dynamic behavior of DFIG under power system disturbance was simulated using MATLAB/SIMULINK.Accurate transient simulations are required to investigate the influence of the wind power on the power system stability. The DFIG considered in this analysis is a wound rotor induction generator with slip rings. The stator is directly connected to the grid and the rotor is interface via a back to back power converter. Power converter are usually controlled utilizing vector control techniques which allow the decoupled control of both active and reactive power flow to the grid. In the present investigation, the dynamic DFIG performance is presented for both normal and abnormal grid conditions. The control performance of DFIG is satisfactory in normal grid conditions and it is found that, both active and reactive power maintains a study pattern in spite of fluctuating wind speed and net electrical power supplied to grid is maintained constant.

REFERENCES:

[1] T. Brekken, and N. Mohan, “A novel doubly-fed induction wind generator control scheme for reactive power control and torque pulsation compensation under unbalanced grid voltage conditions”, IEEE PESC Conf Proc., Vol 2, pp. 760-764, 2003.

[2] L. Xu and Y. Wang, “Dynamic modeling and control of DFIG-based wind turbines under unbalanced network conditions”, IEEE Trans. On Power System, Vol 22, Issues 1, pp. 314-323, 2007.

[3] F.M. Hughes, O. Anaya-Lara, N. Jenkins, and G. Strbac, “Control of DFIG based wind generation for power network support”, IEEE Trans. On Power Systems, Vol 20, pp. 1958-1966, 2005.

[4] S. Seman, J. Niiranen, S. Kanerva, A. Arkkio, and J. Saitz, “Performance study of a doubly fed wind-power induction generator Under Network Disturbances”, IEEE Trans. on Energy Conversion, Vol 21, pp. 883-890, 2006.

[5] T. Thiringer, A. Petersson, and T. Petru, “Grid disturbance response of wind turbines equipped with induction generator and doubly-fed induction generator”, in Proc. IEEE Power Engineering Society General Meeting, Vol 3, pp. 13-17, 2003.

 

Fuzzy Controller for Three Phases Induction Motor Drives

ABSTRACT:

Because of the low maintenance and robustness induction motors have many applications in the industries. Most of these applications need fast and smart speed control system. This paper introduces a smart speed control system for induction motor using fuzzy logic controller. Induction motor is modeled in synchronous reference frame in terms of dq form. The speed control of induction motor is the main issue achieves maximum torque and efficiency. Two speed control techniques, Scalar Control and Indirect Field Oriented Control are used to compare the performance of the control system with fuzzy logic controller. Indirect field oriented control technique with fuzzy logic controller provides better speed control of induction motor especially with high dynamic disturbances. The model is carried out using Matlab/Simulink computer package. The simulation results show the superiority of the fuzzy logic controller in controlling three-phase induction motor with indirect field oriented control technique.

 KEYWORDS:

  1. Vector control
  2. Fuzzy logic
  3. Induction motor drive

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

image001

Fig. 1. Block diagram of scalar controller for IM.

image002

Fig. 2. Indirect Field Oriented Control of IM.

 EXPECTED SIMULATION RESULTS:

 image003

Fig. 3. Speed response of scalar and vector control

image004

Fig 4. Torque response of scalar and vector control.

image005

Fig. 5. Flux response of scalar control.

image006

Fig. 6. Flux response of vector control.

CONCLUSION:

Fuzzy logic controller shows fast control response with three-phase induction motor. Two different control techniques are used with Fuzzy logic controllers which are scalar and field oriented control techniques. Fuzzy logic controller system shows better response with these two techniques. Meanwhile, the scalar controller has a sluggish response than FOC because of the inherent coupling effect in field and torque components. However, the developed fuzzy logic control with FOC shows fast response, smooth performance, and high dynamic response with speed changing and transient conditions.

 REFERENCES:

 [1] A. Mechernene, M. Zerikat and M. Hachblef, “Fuzzy speed regulation for induction motor associated with field-oriented control”, IJ-STA, volume 2, pp. 804-817, 2008.

[2] Leonhard, W.,” Controlled AC drives, a successful transfer from ideas to industrial practice”, CETTI, pp: 1-12, 1995.

[3] M. Tacao, “Commandes numérique de machines asynchrones par lagique floue”, thése de PHD, Université de Lava- faculté des science et de génie Québec, 1997.

[4] Fitzgerald, A.E. et al., Electric Machinery, 5th Edn, McGraw-Hill, 1990.

[5] Marino, R., S. Peresada and P. Valigi, “Adaptive input-output linearizing control of induction motors”, IEEE Trans. Autom. Cont., 1993.