International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 8, August 2017, pp. 1287 1293, Article ID: IJMET_08_08_130 Available online at http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=8&itype=8 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 IAEME Publication Scopus Indexed RENEWABLE ENERGY BASED TORQUE CONTROL OF SQIM BASED ON VOLTAGE ANGLE Assistant Professor, Department of Electrical and Electronics Engineering, Veltech Dr. RR & Dr. SR University, Chennai, India ABSTRACT In a motor control, voltage saturation is a serious problem when a motor speed tends to increase. To solve the problem, various flux weakening methods were studied for a long time. The field weakening with PI controllers are normally used,however the voltage angle control without PI controllers is receiving attention because of its easy implementation In this work, a torque control method is proposed based on Voltage angle control using Renewable energy as PV is implemented.the simulations were conducted to verify the proposed method. Keywords: SQIM drive, voltage angle control. Cite this Article: Mr. Prabu. K, Mr. Vinoth John Prakash. S, Mr. Barathi. K, Mr. Gopikaramanan R, Renewable Energy Based Torque Control of Sqim Based on Voltage Angle, International Journal of Mechanical Engineering and Technology 8(8), 2017, pp. 1287 1293. http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=8&itype=8 1. INTRODUCTION A Squirrel cage induction motor (SQIM) are the most common motors used in industrial drives and home appliances because of its Simple, rugged design, low-cost and require less maintenance. Voltage saturation problem occurs, when frequency changes Synchronous speed changes, with decrease in frequency flux will increase and this change in value of flux causes saturation of rotor and stator cores which will further cause increase in no load current of the motor. So, it s important to maintain flux constant and it is only possible if we change voltage. The field weakening control is advisable to avoid the voltage saturation [1][2] Therefore, there have been many researches on the field-weakening control scheme of the SQIM. In [3], a feed forward based field-weakening control was implemented. The method is sensitive to the motor parameters so that the voltage margin is necessary. To reduce the sensitivity to the machine parameter, a stator voltage feedback based field-weakening control was implemented [4] to control the stator voltage, proportion and integral (PI) controller was used, thus additional gain tuning is needed. http://www.iaeme.com/ijmet/index.asp 1287 editor@iaeme.com
Renewable Energy Based Torque Control of Sqim Based on Voltage Angle In the field weakening control, the maximum stator voltage is always utilized; thereby the only thing to remain is to determine the voltage angle. Therefore, the voltage angle controllers without the PI current controllers were studied previously [6]-[7]. They does not require a voltage margin and uses a single PI controller, however, their main drawback is weak stability. On the other hand, the six-step operation has many advantages in the high speed region: it expands the voltage utilization range and it reduces the number of switching s [5]. However, the conventional PI current controllers hardly used, because of the undesired current harmonics [9], [10]. For this reason, the voltage angle control was adopted for the sixstep operation [11]-[14]. In [11], the voltage angle was obtained using only PI controller, thus it has weak stability. In this work the induction motor with torque control technique is proposed. Torque constant for irrespective of speed. The voltage angle control technique is implemented sudden change in load causes hunting problem. The mechanical transient from load side removed by voltage angle control method. The controller used to control the speed and also fixed the torque constantly. The source proposed for this model is Renewable energy source in order to reduce the conversion losses occurs in converters. 2. RELATION BETWEEN VOLTAGE AND TORQUE A. SQIM Model In three phases induction motors the emf induced by induction similar to that of transformer is given by =4.44 (1) Where K is the winding constant, T is the number of turns per phase and f is frequency. =. Controlling supply voltage: The torque produced by running three phase induction motor is given by (3) In low slip region (sx) 2 is very small as compared to R 2. So, it can be neglected. So torque becomes (4) Since rotor resistance R 2 is constant so the equation of torque further reduces to (5) We know that rotor induced emf E 2 V. So, T sv 2.From the equation above it is clear that if we decrease supply voltage torque will also decrease. But for supplying the same load, the torque must remain the same.in our model; we proposed voltage angle measurement by making torque constant irrespective of load. The Voltage angle control algorithm helps by providing both a magnitude and angle between the voltage and current.. By controlling this angle, low speed operation and torque control are improved over the standard drive. Thus, the control algorithms can be arranged to minimize the dependence on motor parameters. This methodology improves the performance of drive under all the operating condition and field weakening method can be reduced in order to increase the life time of the equipment. (2) http://www.iaeme.com/ijmet/index.asp 1288 editor@iaeme.com
3. BLOCK DIAGRAMFOR PROPOSED MODEL Figure 1 Block Diagram of Proposed Model The proposed model enhances the system stability by usage of Renewable energy which overcomes the losses involved in other sources. The existing system with IPMSM Based on voltage angle method with d-axis concept was implemented to make system stability better [15]. To reduce complexity in design PI controller along with voltage angle control of SQIM was implemented at various load conditions The input supply is extracted from the renewable energy source is fed in to the inverter circuit for production of three phase supply for SQIM. The filters are placed in between source and Inverter in order to damp the unnecessary oscillations that occur in circuits. The three phase output from six-pulse converter is given to LC filter in order to reduce extinction angle due to inductive load as well as to reduce higher order harmonics that occurs normally in ac circuits. By comparing the reference voltage with the inverter output is compared with controller for producing gate pulse to trigger inverter circuit during the operation. Controller s compares voltage angle with reference voltage angle irrespective load change the torque will be maintained constant by giving a feedback modulated value to torque parameter through inverter circuit. By providing PWM techniques adds additional advantage to our proposed model Voltage feedback was studied in this work. In the simulation, and the experimental results, the proposed method worked well in the transient and steady state region. 3.1 VOLTAGEANGLE CONTROL ALGORITHM The phase angle of a line voltage is used to calculate and control the flow of active/reactive power, and transform the feedback variables to a synchronous reference frame (SRF). The phase angle, therefore, is critical piece of information for the operation of most power conditioning equipment such as: controlled AC/DC converter, UPS, series voltage compensator, static VAR compensator, active filter, etc. If voltage sag takes place in one or two phases in a three-phase power system, it causes voltage unbalance by generating a negative sequence voltage. The voltage unbalance induces an oscillating error in the measurement of the phase angle. In the power conditioning equipment, if there is an error in the phase angle estimation then it may directly correct the compensation voltage, and thus deteriorate the performance. To avoid the performance deterioration, it is necessary to find the positive and the negative sequence voltage instantaneously. However it is normally difficult to estimate the positive and the negative sequences separately from their summed values. Considering the torque controller to ensure perfect tracking of the output torque and providing means for eliminating torque fluctuations, the frequency based disturbances to be eliminated should be included in the stable closed-loop system. At this condition, the tracking http://www.iaeme.com/ijmet/index.asp 1289 editor@iaeme.com
Renewable Energy Based Torque Control of Sqim Based on Voltage Angle error will not contain these frequency modes. This criterion is satisfied if the torque controller can supply an internal model. This approach has been used in the study where an iterative learning controller is used to supply an internal model in the reference-current-generating controller. However, the iterative control is not easy to stabilize for all unknown disturbances and cannot obtain very fast response. Another approach to design the torque controller is employing the variable-structure control (VSC). In the VSC approach, a discontinuous fast switching control law forces an infinite gain at the equilibrium point. Subsequently, a wideband of frequency modes are supplied through an equivalent internal model. By this technique, a wide range of perturbations can be rejected. However, the approach has practical limitations, such as chattering and nonlinear sliding-motion effects, which arise from the extremely high gain around the equilibrium and the limited switching frequency. 4. CIRCUIT DIAGRAM Figure 2 Circuit configuration of proposed model The circuit diagram for the proposed model is shown above. The Saturatable reactor is used for creating a reactance in order to measure the voltage angle of squirrel cage induction motor. The implementation of Hardware and its results were discussed in this paper. PIC microcontroller is used to generate pulse to the inverter circuit based on voltage angle parameter measured from the motor input supply.pic microcontroller provide more advantages than the other controller because of inbuilt DC facilities with the other features. Figure 3 Hardware Circuit Diagram http://www.iaeme.com/ijmet/index.asp 1290 editor@iaeme.com
Figure 4 PIC MICROCONTROLLER 5. SIMULATION CIRCUITS WITH RESULTS Figure 5 Matlab Simulink Blocks Waveform A: Output of AC Voltage http://www.iaeme.com/ijmet/index.asp 1291 editor@iaeme.com
Renewable Energy Based Torque Control of Sqim Based on Voltage Angle Waveform B: Output of Modulation Waveform C: Output of speed and Torque Waveform D: Output of Rotor angle For modulation and the corresponding speed the angle will be maintain in constant level. Thus the torque also maintained in stable manner. To control torque at low speed, quick change of δ can be obtained by avoiding the zero voltage vectors and by applying vectors which move the stator flux relative to rotor flux as quickly as possible. At high speed, this may not be necessary where the rotor move sufficiently to produce the required change in torque. 6. CONCLUSION The inverter output voltage will be shown corresponding to the squirrel cage induction motor at various load conditions. The mechanical parameters don t take from the motor. It is torque fixing method, so we only taken the temperature and angular displacement. Sudden change in load affects the inverter output voltage. Because the motor will be directly connected to the motor through the load. Also single PWM controller gives the pulses to the thyristors that are placed in the inverter circuit. REFERENCES [1] W. L. Soong and T. J. E. Miller, Theoretical limitations to the Field weakening performance of the five classes of brushless synchronous AC drives, in Proc. IEEE IEMDC, pp. 127-132,1993. http://www.iaeme.com/ijmet/index.asp 1292 editor@iaeme.com
[2] W. L. Soong and T. J. E. Miller, Field-weakening performance of brushless synchronous AC motor drives, in Proc. Inst. Electr Eng., vol. 141, no. 6, pt. B, pp. 331-340, Nov. 1994. [3] S. Morimoto, M. Sanada, and Y. Takeda, Wide-speed operation of interior permanent magnet synchronous motors with high performance current regulator, IEEE Trans. Ind. Appl, volume. 30, no. 4, pp. 920-926, Jul. /Aug. 1994. [4] J. M. Kim and S. K. Sul, Speed control of interior permanent magnet synchronous motor drive for the ux weakening operation, IEEE Trans. Ind. Appl, volume. 33, no. 1, pp. 43-48, Jan. /Feb. 1997. [5] J. Holtz, W. Lotzkat and M. Khambadkone, on continuous control of PWM inverters in the over modulation range including the six-step mode, IEEE Trans. Power Electron., volume. 8, no. 4, pp.546-553, Oct. 1993. [6] L. Zhu, S. Xue, X. Wen, Y. Li, and L. Kong, A New Deep Field-Weakening Strategy of IPM Machines based on Single Current Regulator and Voltage Angle Control, in Proceedings of theecce 2010, pp. 1144-1149, 2010. [7] W. Hatsuse, Y. Notohara, K. Ohi, K. Tobari, K. Tamura, C. Unoko, and Y. Iwaji, A Stable Field-Weakening Control Using Voltage Phase Operations in the High-Power Region, in The 2010 IPEC, pp.599-604, 2010. [8] D. Stojan, D. Drevensek, Z. Plantic, B. Grcar, and G. Stum-berger, Novel Field- Weakening Control Scheme for Permanent-Magnet Synchronous Machines based on Voltage Angle Control, in IEEE Trans. on Industry Applications, volume. 48, no. 6, pp. 2390-2401, 2012. [9] A. M. Khambadkone and J. Holtz, Compensated Synchronous PI Current Controller in Overmodulation Range and Six-Step Operation of Space-Vector-Modulation-based Vector-Controlled Drives, in IEEE Trans. Ind. Electron., volume. 49, no. 3, pp. 574-580, Jun. 2002. [10] S. Lerdudomsak, M. Kadota, S. Doki and S. Okuma, Harmonic Currents Estimation and Compensation Method for Current Control system of IPMSM in over modulation range, in Proc of the PCC nagoya 2007, pp. 1320-1326, 2007. [11] H. Nakai, H. Ohtani, E. Satoh, and Y. Inaguma, Development and Testing of the Torque Control for the Permanent-Magnet Synchronous Motor, in IEEE Trans. Ind. Electron., volume. 52, no.3, pp. 800-806, Jun. 2005. [12] S. H. Kim, and J. K. Seok, Maximum Voltage Utilization of IPMSMs Using Modulating Voltage Scalability for Automotive Applications, in IEEE Trans. Power Electron., volume. 28, no. 12, pp. 5639-5646. Dec. 2013. [13] T. Schoenen, A. Krings, D. van Treek, and R. De Doncker, Maximum DC-link Voltage Utilization for Optimal Operation of IPMSM, in IEEE International IEMDC 09, 3-6 2009, pp.1547-1550. [14] T. Miyajima, H. Fujimoto, and M. Fujitsuna, A Precise Model- Based Design of Voltage Phase Controller for IPMSM, in IEEE Trans. Power Electron, vol. 28, pp. 5655-5663, Dec. 2013. [15] Torque Control for IPMSM in the High Speed Range Based on Voltage Angle Heekwang Lee, Junwoo Kim, Jinseok Hong and Kwanghee Nam 978-1-4799-2325-0/14/$31.00 2014 IEEE. [16] Manish Kaushik, Vikash Kumar, Pramesh Kumar, Direct Torque Control of Induction Motor Using Space Vector Modulation, International Journal of Electrical Engineering and Technology (IJEET), Volume 4, Issue 5, September October (2013), pp. 01-08. [17] Ritu Tak, Sudhir Y Kumar and B. S. Rajpurohit, Modeling The Torque Control Scheme of Surface Mounted Permanent Magnet Synchronous Motor, International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp. 1137-1146. http://www.iaeme.com/ijmet/index.asp 1293 editor@iaeme.com