Sensor less Speed Control of Induction Motor Using MRAS

ABSTRACT:

In order to implement the vector control technique, the motor speed information is required. Tachogenerators, resolvers or incremental encoders are used to detect the speed. These sensors require careful mounting and alignment and special attention is required with electrical noises. Speed sensor needs additional space for mounting and maintenance and hence increases the cost and the size of the drive system .These problems are eliminated by speed sensorless vector control by using model reference adaptive system. Model reference adaptive system is a speed estimation method having two models namely reference and adaptive model .The error between two models estimates induction motor speed. This project proposes a Model Reference Adaptive System (MRAS) for estimation of speed of induction motor. An Induction motor is developed in stationary reference frame and Space Vector Pulse Width Modulation (SVPWM) is used for inverter design. PI controllers are designed controlling purpose. It has good tracking and attains steady state response very quickly which is shown in simulation results by using MATLAB/SIMULINK.

KEYWORDS:

1.      Sensorless vector control

2.       Model Reference Adaptive System (MRAS)

3.       Induction motor

4.       stationary reference frame

5.       Speed estimation

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                     

Fig 1:Block Diagram of Sensor less Control of Induction Motor

                       

Fig 2: block diagram of MRAS

EXPECTED SIMULATION RESULTS:

                 

                         

Fig 3: 3-f currents, Speed, and Torque for no-load reference speed of 100 rad/sec

               

Fig 4:3-f currents, Speed, and Torque for no-load reference speed of 100 rad/sec

               

Fig 5: 3 -f currents, Speed, and Torque for step signal

CONCLUSION:

In this thesis, Sensorless control of induction motor using Model Reference Adaptive System (MRAS) technique has been proposed. Sensorless control gives the benefits of Vector control without using any shaft encoder. In this thesis the principle of vector control and Sensorless control of induction motor are given elaborately. Simulation results of Vector Control and Sensorless Control of induction motor using MRAS technique were carried out by using Matlab/Simulink. From the simulation results, the following observations are made.

i) The transient response of the drive is fast, i.e. we are attaining steady state very quickly.

ii) By using MRAS we are estimating the speed, which is same as that of actual speed of induction motor.

Thus by using sensor less control we can get the same results as that of vector control without shaft encoder. Hence by using this proposed technique, we can reduce the cost of drive i.e. shaft encoder’s cost, we can also increase the ruggedness of the motor as well as fast dynamic response can be achieved.

REFERENCES:

[1] Abbondanti, A. and Brennen, M.B. (1975). “Variable speed induction motor drives use electronic slip calculator based on motor voltages and currents”. IEEE Transactions on Industrial Applications, vol. IA-11, no. 5: pp. 483-488.

[2] Nabae, A. (1982). “Inverter fed induction motor drive system with and instantaneous slip estimation circuit”. Int. Power Electronics Conf., pp. 322-327.

[3] Jotten, R. and Maeder, G. (1983). “Control methods for good dynamic performance induction motor drives based on current and voltages as measured quantities”. IEEE Transactions on Industrial Applications, vol. IA-19, no. 3: pp. 356-363.

[4] Amstrong, G. J., Atkinson, D. J. and Acarnley, P. P. (1997). “A comparison of estimation techniques for sensorless vector controller induction motor drives”. Proc. Of IEEE-PEDS.

[5] Wang yaonan,lu jintao,haung shoudao(2007).”speed sensorless vector control of induction motor based on MRAS theory”.

A seventeen-level inverter with a single DC link for motor drives

           

ABSTRACT:  

In the present paper, a novel topology for generating a 17–level inverter using three-level flying capacitor inverter and cascaded H-bridge modules with floating capacitors. The proposed circuit is analyzed and various aspects of it are presented in the paper. This circuit is experimentally verified and the results are shown. The stability of the capacitor balancing algorithm has been verified during sudden acceleration. This circuit has many pole voltage redundancies. This circuit has an advantage of balancing all the capacitor voltages instantaneously by switching through the redundancies. Another advantage of this topology is its ability to generate all the 17 pole voltages from a single DC link which enables back to back converter operation. Also, the proposed inverter can be operated at all load power factors and modulation indices. Another advantage is, if one of the H-bridges fail, the inverter can still be operated at full load with reduced number of levels.

KEYWORDS:

1.      Seventeen level inverter

2.       Multilevel inverter

3.      Flying Capacitor

4.       Cascaded H-bridge

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

       

Fig.1. Proposed seventeen level inverter configuration formed by cascading three level flying capacitor inverter with 3 H-bridges using a Single DC link.

EXPECTED SIMULATION RESULTS:

         

                                                                  (a)

                                                                    (b) 

                        

                                                                    (c)

                  

                                                                    (d)

Fig.2: Voltages of  Capacitors C2, C3, C4 along with the phase current IA

(a)  10Hz operation, VAC4: (100V/div), VAC3: (10V/div), VAC2: (25V/div),IA:5A/div, Timescale: (20 mS/div).

(b)  20Hz operation, VAC4: (20V/div), VAC3: (10V/div), VAC2: (25V/div),IA:2A/div, Timescale: 10mS/div

(c)  30Hz operation, VAC4: (20V/div), VAC3: (10V/div), VAC2: (25V/div),IA:2A/div, Timescale: 10mS/div

(d)  40Hz operation, VAC4: (10V/div), VAC3: (10V/div), VAC2: (100V/div), IA:2A/div,Timescale:5mS/div

                          

                                 

                           

                                                                       (a)

                       

                                                                       (b)

                          

                                                                       (c)

                            

                                                                      (d)

Fig.3: Voltages of  Cap1 with Pole voltage VAO, Phase A Voltage VAN and  phase current IA. 

(a)   10Hz operation, VAC1( 50V/div), VAO: Pole voltage( 100V/div),VAN: Phase Voltage (100V/div),  IA: 2A/div, Timescale: (20mS/div).

(b)  20Hz operation, VAC1: ( 50V/div), VAO: Pole voltage( 100V/div),VAN: Phase Voltage (100V/div),  IA: 2A/div, Timescale: (10mS/div).

(c)    30Hz operation, VAC1: ( 50V/div), VAO: Pole voltage( 100V/div), VAN: Phase Voltage (100V/div),  IA: 2A/div, Timescale: (10mS/div).

(d)    40Hz operation, VAC1: ( 50V/div), VAO: Pole voltage( 100V/div),VAN: Phase Voltage (100V/div),  IA: 2A/div, Timescale: (10mS/div).

                    

                                                                      (a)

                                                                        (b)

Fig.4.  Performance of the capacitor balancing algorithm during sudden acceleration at no load from 10Hz to 40Hz  (a) VAC1:Cap AC1 voltage(100V/div), VAO: Pole Voltage(100V/div) , VAN: Phase Voltage(100V/div), IA: Phase current(2A/div)  (b) VAC4:Cap AC4 voltage(10V/div), VAC3:Cap AC3 voltage (20V/div), VAC2:Cap AC2 voltage (20V/div), IA: Phase current(2A/div)

CONCLUSION:

A  seventeen  level  inverter  formed  by  cascading  a  three level  flying  capacitor  with  floating  capacitor  H-bridges  has been proposed. The proposed inverter has reduced number of  switches as compared with standard configurations.  The  inverter  has  other  advantages  like  ability  to  balance  all  the  capacitor voltages at all  load currents and power  factors  there  by  generating  seventeen  pole  voltages  with  very  little  distortion.   Another advantage of  the  inverter  is ability  to generate all  the  required  voltage  levels  using  a  single  DC  link.  This  possibility  of  using  single  DC  link  enables  back  to  back  converter  operation  where  a  front  end  can  be  used  so  that  power  can  be  drawn  and  supplied  to  grid  at  desired  power  1%#' factor. Another important advantage is if one of devices in one of H-bridges fail, the inverter can still be operated at full load at reduced number of levels.  The proposed  inverter  is  analyzed  and  its  performance  is  experimentally  verified  for  various  modulation  indices  and  load  currents  by  running  a  three  phase  3kW  squirrel  cage  induction  motor.  The  stability  of  the  capacitor  balancing  algorithm  has  been  tested  experimentally  by  suddenly  accelerating  the motor  at no  load  and observing  the  capacitor  voltages at various load currents.

REFERENCES:

 [1] L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, M.A.M.  Prats,  “The  age  of multilevel  converters  arrives,”  IEEE  Ind.  Electron.  Magazine, vol. 2, no. 2, pp. 28–39, June.2008.

[2] S.  Kouro,  M.  Malinowski,  K.  Gopakumar,  J.  Pou,  L.  G.  Franquelo,  B.Wu, J. Rodriguez, M. A. Perez, and J. I. Leon, “Recent Advances and  Industrial  Applications  of  Multilevel  Converters,”  IEEE  Trans.  Ind.  Electron.,vol. 57, no. 8, pp. 2553–2580, Aug. 2010.

[3] A. Nabae,  I.  Takahashi,  and H. Akagi,  “A  new  neutral-point-clamped  PWM inverter,” IEEE Trans. Ind. Appl., vol. IA-17, no. 5, pp. 518–523,  Sep. 1981. 

[4] M. Marchesoni, M. Mazzucchelli, and S. Tenconi, “A non-conventional  power  converter  for  plasma  stabilization,”  in  Proc.  IEEE  19th  Annu.  Power  Electron.  Spec. Conf.  (PESC’88) Rec., Apr.  11–14,  vol.  1,  pp.  122–129.

[5] Z.  Du,  L.M.  Tolbert,  J.  N.  Chiasson,  B.  Ozpineci,  H.  Li,  and  A.  Q.  Huang,  “Hybrid  cascaded H-bridges multilevel motor drive  control  for  electric vehicles,” in Proc. IEEE 37th Power Electron. Spec. Conf., Jun.  18–22, 2006, pp. 1–6.

Modeling and Simulation of Micro-grid Based on Small-hydro

ABSTRACT:

As a renewable resource, small hydro is gaining more and more attention due to its variable advantages. The paper focuses on the operation of the micro-grid based on small-hydro. A simulation model of the micro-grid is established by Simulink, which takes the following two cases into account, the grid-connected operation and isolated operation. Under these two cases, the differences of the excitation voltage and rotator speed are analyzed respectively. Power quality of the voltage is also analyzed. Faults are pre-set in the grid and micro-grid. Then the operations of the micro-grid when faults happen are simulated. By comparison of the results, the effects of the fault-cutting-off time are discussed.

KEYWORDS:

1.      Small-hydro

2.       Micro-grid

3.       Model

4.       Simulation

5.      Faults

SOFTWARE: MATLAB/SIMULINK

 SIMULING BLOCK DIAGRAM:

 Fig. 1. Simulation model of the entire system

EXPECTED SIMULATION RESULTS:

             

  Fig. 2. Field voltage of generator

             

                                            

    Fig. 3. Rotator speed of generator

 

                                

    Fig. 4. Output voltage (RMS) of generator 1(THD=0.80%)

                              

                               

      Fig. 5. Active power assumption of load 1

                                    

                                

         Fig. 6. Field voltage of generator

    

                               

 Fig. 7. Rotator speed of generator

                              

 

  Fig. 8. Output voltage (RMS) of generator 1(THD=1.91%) 

 

  

   Fig. 9. Active power assumption of load 1

        

       Fig. 10. Field voltage of generator

         

 Fig. 11. Rotator speed of generator

              

    Fig. 12. Output voltage (RMS) of generator 1

 

         

Fig. 13. Active power assumption of load 1

 

                                    

  Fig. 14. Field voltage of generator     

         Fig. 15. Rotator speed of generator

 

    

       Fig. 16. Output voltage (RMS) of generator 1

 

       

Fig. 17. Active power assumption of load 1

          

   Fig. 18. Field voltage of generator

                                    

                                  

Fig. 19. Rotator speed of generator

 

                                 

  Fig. 20. Output voltage (RMS) of generator 1

                                  

 

Fig. 21. Active power assumption of load 1

CONCLUSION:

The micro-grid based on small-hydro can work normally without disturbance by simulating the grid-connected operation and islanded operation. The power quality would have been improved when the micro-grid connected to the grid by comparing the waveforms of output voltage and active power assumption. And the THD would have decreased when the micro grid is in grid-connected operation. Analyze the recovering time and influence of fault-cutting time by setting fault to the micro-grid and grid. The simulation results stress the importance of fault-cutting time. Cutting off the fault in time would suppress the system oscillation, and the generators are easier to get synchronous again. The system would oscillate fiercely with high frequency if the fault could not be cut off in time. However, the actual situation is more complex. Considering the change of load, actual situation of small-hydro power plants (changes of water level and so on), development of different distributing power and so on, the structure of the conventional micro-grid will become more complex, so the model in the paper needs some improvement.

 REFERENCES:

[1] Tao YU,Haihua LIANG. “Smart power generation control for microgrids islanded operation based on reinforcement leaning”,. Master's degree thesis of south china university of technoiogy,2012

[2] Fred H. Schwartz, Mohammad Shahidehpour. “Small Hydro As Green Power.” Power Engineering Society General Meeting, USA, 2005, pp. 2050 - 2057.

[3] ZHANG YuanSheng, et al. “The effects on the load model of the distributed network with small hydro power.” 2011 The International Conference on Advanced Power System Automation and Protection, China, 2011, pp.911-916.

[4] Anuradha Wijesinghe, Loi Lei. “Small Hydro Power Plant Analysis and Development,” Electric Utility Deregulation and Restructuring and Power Technologies (DRPT), China, 2011, pp.25 –30.

[5] Guillermo C. Zu˜niga-Neria, Fernando Ornelas-Tellez,J. Jesus Rico. “Optimal Operation of Energy Resources in a Micro-grid.” Power Systems Conference, USA, 2014, pp. 1-6.