Novel Back EMF Zero Difference Point Detection Based Sensorless Technique for BLDC Motor

ABSTRACT

In this paper a novel position sensorless scheme named Back EMF Zero Difference Point (ZDP) detection has been proposed for six-switch VSI converter fed permanent magnet BLDC motor. This technique is based on the comparison of back EMFs and detection of the points in the back EMF waveforms where they cross each other or in other words they are equal. Commutation point is achieved exactly at the same instant when the difference of back EMFs of any two phases becomes zero. The simulation study has been carried out for the proposed sensorless scheme. The proposed sensorless scheme has the excellent performance from zero to the extra high speed. The method needs no additional delay circuit as used for calculation of commutation point from back EMF ZCP and involves less calculation burden. The method is fault tolerant and accurate even in the case of noise in measurement (or estimation) of phase back EMFs. A nonzero threshold value proportional to input voltage (or reference speed) is used for overcoming the problem due to quantization and sampling for digital implementation. This method proves to be excellent substitute of hall sensing scheme as it also senses at zero speed.

KEYWORDS:

1.      BLDC motor

2.      Back EMF ZDP

3.      Commutation

4.      Sensorless control

5.      Zero difference point.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig.1 VSI fed BLDC motor with indirect Back EMF detection scheme

EXPECTED SIMULATION RESULTS:

Fig.2. Phase Back EMF ZDPs, switching signals, counter output and triggering sequence signals.

Fig.3. Steady state operation at the low speed of 600 rpm.

Fig.4. performance of proposed sensorless scheme at 17000 rpm

Fig.5. Noise immune performance during steady state operation for reference speed of 17000rpm.

Fig.6. sensing fault occurs at 0.5 second in the measurement of phase-B back EMF.

Fig.7. speed increases when sensing fault occurs (here phase-B sensing fault

CONCLUSION

In the proposed Back EMF Zero Difference Point (ZDP) detection method, the very first commutation signal is achieved at starting itself i.e. one step before the ZCP method, which proves the superiority of the method. The back EMF for the proposed scheme can be applied to various existing back EMF detection or estimation techniques. This technique is insensitive to the inherent noise in measurement (or estimation) of back EMF. This method does not need extra circuitry as needed for delay after ZCP for getting commutation point, thereby less computational complexity is involved. The speed (or input voltage) proportional threshold used for avoiding uncertainty in the zero difference of back EMF, sets its scope of wide usability in precise operation from zero to extra high speed. Operation at initial zero back EMF is the main strength of this method and it doesn’t necessitate separate starting techniques. Speed response at transient period is 0.15 ms faster than previous methods for identical motor parameters.

REFERENCES

[1]   M.V.Kesava Rao, Department of Electrical technology, IISc Bangalore, ‘‘Brush Contact Drops in DC machines’’, Accepted 25-6-1934, Bangalore Press.

[2]    Y.S. Jeon, H.S. Mok, G.H. Choe, D.K. Kim, J.S. Ryu, “A New Simulation Model of BLDC Motor with Real Back EMF waveform”, 7 th workshop on Computers in power Electronics , 2000 (COMPEL 2000), page 217- 220.

[3]   Padmaja yedmale, “Brushless DC (BLDC) Motor Fundamentals”, AN885, 2003 Microchip Technology.

[4]    S. Tara , Syfullah Khan Md “Simulation of sensorless operation of BLDC motor based on the zero cross detection from the line voltage” International Journal of Advanced Research in Electrical Electronics and Instrumentation Engineering, vol 2, issue 12 , December 2013, ISSN 2320-3765.

J. R. Frus and B. C. Kuo, “Closed-loop control of step motors using waveform detection,” in Proc. Int. Conf. Stepping Motors and Systems, Leeds, U.K., 1976, pp. 77–84.

Power Quality Improvement and Mitigation Case Study Using Distributed Power Flow Controller

ABSTRACT

According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, voltage sag and swell of the power quality issues are studied and distributed power flow controller (DPFC) is used to mitigate the voltage deviation and improve power quality. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. The case study contains a DPFC sited in a single-machine infinite bus power system including two parallel transmission lines, which simulated in MATLAB/Simulink environment. The presented simulation results validate the DPFC ability to improve the power quality.

KEYWORDS:

1.      FACTS

2.      Power Quality

3.      Sag and Swell Mitigation

4.      Distributed Power Flow Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. The DPFC Structure

EXPECTED SIMULATION RESULTS:

Fig. 2. Three-phase load voltage sag waveform

Fig. 3. Mitigation of three-phase load voltage sag with DPFC

Fig. 4. Three-phase load current swell waveform without DPFC

Fig. 5. Mitigation of three-phase load current swell with DPFC

Fig. 6. Total harmonic distortion of load voltage without DPFC

Fig. 7. Total harmonic distortion of load voltage with DPFC

CONCLUSION

To improve power quality in the power transmission system, there are some effective methods. In this paper, the voltage sag and swell mitigation, using a new FACTS device called distributed power flow controller (DPFC) is presented. The DPFC structure is similar to unified power flow controller (UPFC) and has a same control capability to balance the line parameters, i.e., line impedance, transmission angle, and bus voltage magnitude. However, the DPFC offers some advantages, in comparison with UPFC, such as high control capability, high reliability, and low cost. The DPFC is modeled and three control loops, i.e., central controller, series control, and shunt control are design. The system under study is a single machine infinite-bus system, with and without DPFC. To simulate the dynamic performance, a three-phase fault is considered near the load. It is shown that the DPFC gives an acceptable performance in power quality mitigation and power flow control.

REFERENCES

[1]   S. Masoud Barakati, Arash Khoshkbar Sadigh and Ehsan Mokhtarpour, “Voltage Sag and Swell Compensation with DVR Based on Asymmetrical Cascade Multicell Converter” , North American Power Symposium (NAPS), pp.1 – 7, 2011

[2]   Alexander Eigels Emanuel, John A. McNeill “Electric Power Quality”. Annu. Rev. Energy Environ 1997, pp. 263-303.

[3]    I Nita R. Patne, Krishna L. Thakre “Factor Affecting Characteristics Of Voltage Sag Due to Fault in the Power System” Serbian Journal Of Electrical engineering. vol. 5, no.1, May2008, pp. 171-182.

[4]   J. R. Enslin, “Unified approach to power quality mitigation,” in Proc. IEEE Int. Symp. Industrial Electronics (ISIE ’98), vol. 1, 1998, pp. 8– 20.

[5]    B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron. vol. 46, no. 5, pp. 960–971, 1999.

Designing of Multilevel DPFC to Improve Power Quality

ABSTRACT

According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, Enhancement of power quality by using fuzzy based multilevel power flow controller (DPFC) is proposed. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. This eventually enables the DPFC to fully control all power system parameters. It, also, increases the reliability of the device and reduces its cost simultaneously. In recent years multi level inverters are used high power and high voltage applications .Multilevel inverter output voltage produce a staircase output waveform, this waveform look like a sinusoidal waveform leads to reduction in Harmonics. Fuzzy Logic is used for optimal designing of controller parameters. Application of Fuzzy Multilevel DPFC for reduction of Total Harmonic Distortion was presented. The simulation results show the improvement of power quality using DPFC with Fuzzy logic controller.

KEYWORDS:

1.      FACTS

2.      Power Quality

3.      Multi Level Inverters

4.      Fuzzy Logic

5.      Distributed Power Flow Controller component

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1: The DPFC Structure

EXPECTED SIMULATION RESULTS:

Fig.2: 5 Level Voltage Waveform

Fig.3: Three Phase output Voltage and Current Waveform

Fig.4: Supply Voltage and Current Waveform with unity PF

Fig.5: THD with out fuzzy

Fig.6: THD with fuzzy

CONCLUSION

In this paper Fuzzy Logic Controller technique based distributed power flow controller (DPFC) with multilevel voltage source converter (VSC) is proposed. The presented DPFC control system can regulate active and reactive power flow of the transmission line. We are reducing the THD value from 24.84% to 0.41% by using this technic as shown in fig’s (12) & (13).The series converter of the DPFC employs the DFACTS concept, which uses multiple converters instead of one large-size converter. The reliability of the DPFC is greatly increased because of the redundancy of the series converters. The total cost of the DPFC is also much lower than the UPFC, because no high-voltage isolation is required at the series converter part and the rating of the components are low. Also results show the valid improvement in Power Quality using Fuzzy Logic based Multilevel DPFC.

REFERENCES

[1]   K Chandrasekaran, P A Vengkatachalam, Mohd Noh Karsiti and K S Rama Rao, “Mitigation of Power Quality Disturbances”, Journal of Theoretical and Applied Information Technology, Vol.8, No.2, pp.105- 116, 2009

[2]    Priyanka Chhabra, “Study of Different Methods for Enhancing Power Quality Problems”, International Journal of Current Engineering and Technology, Vol.3, No.2, pp.403-410, 2013

[3]    Bindeshwar Singh, Indresh Yadav and Dilip Kumar, “Mitigation of Power Quality Problems Using FACTS Controllers in an Integrated Power System Environment: A Comprehensive Survey”, International Journal of Computer Science and Artificial Intelligence, Vol.1, No.1, pp.1-12, 2011

[4]    Ganesh Prasad Reddy and K Ramesh Reddy, “Power Quality Improvement Using Neural Network Controller Based Cascaded HBridge Multilevel Inverter Type D-STATCOM”, International Conference on Computer Communication and Informatics, 2012

[5]   Lin Xu and Yang Han, “Effective Controller Design for the Cascaded Hbridge Multilevel DSTATCOM for Reactive Compensation in Distribution Utilities”, Elektrotehniski Vestnik, Vol.78, No.4, pp.229- 235, 2011

Smooth Shunt Control of a Fuzzy based Distributed Power Flow Controller to Improve Power Quality

ABSTRACT

Presently, the quality of power supplied is essential to many customers. Power quality (PQ) is a valued utility service where many customers are prepared to pay and get it. In the future, distribution system operators ought to decide, to provide their customers with distinct PQ ranges at different prices. Here, in this paper, a new control action to improve and maintain and enhance the power quality of an electrical power system is proposed in this paper. Fuzzy based distributed power flow controller (DPFC) is designed and put into action to compensate the voltage imbalances arising in a power system. This customized DPFC is an advanced FACTS device, which has its structure analogous to unified power flow controller (UPFC). DPFC comprises of both series and shunt converters, in which its three phase series converter is distributed over the transmission line as several single phase static converters ensuring high controllability and reliability at a low cost compared to an UPFC. A central controlling circuit is designed to supply reference signals to each of the individual controlling circuits of both series and shunt converters. This customized device is applied to a single machine infinite bus power system having nonlinear loads connected to it and is simulated in MATLAB/Simulink environment by using OPAL-RT 5600 Real-time digital Simulator. The results demonstrate the validation of proposed technique to enhance the power quality.

KEYWORDS:

1.      Power quality

2.      Voltage fluctuations

3.      Harmonic analysis

4.      Power harmonic filters

5.      Voltage control

6.      Load flow Voltage Sag and Swell

7.      Fuzzy Logic.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Basic configuration of DPFC

EXPECTED SIMULATION RESULTS:

Fig. 2. Voltage waveform during fault condition

Fig. 3. Current waveform during fault condition

Fig. 4. Simulated results for Voltage by employing DPFC controller

Fig. 5. Simulated results for Current by employing DPFC controller

Fig. 6. THD of load voltage without Controller

Fig. 7. FFT Analysis for PI Controller

Fig. 8. FFT Analysis for Fuzzy Controller

CONCLUSION

The work is presented to provide a solution for maintaining Power Quality at the distribution end, compensation of harmonics in grid voltage and in load currents. In order to consummate specified intentions in this paper a new concept for controlling power quality problems was proposed and implemented. By putting the customized device into action, results were analyzed for voltage dips and their mitigations for a three phase source with non-linear loads. The DPFC is modeled by positioning three control circuits designed independently. In this paper we also proposed and implemented the concept of fuzzy logic controller for having better controlling action, which will help in minimization/elimination of harmonics in the system. As compared to all other facts devices the Fuzzy based DPFC converter effectively controls all power quality problems and with this technique we can put THD to 3.04% proving the effectiveness of the proposed controller.

REFERENCES

[1]   D. Divan and H. Johal, “Distributed facts-A new concept for realizing grid power flow control,” in IEEE 36th Power Electron. Spec. Conf. (PESC), 2005, pp. 8–14.

[2]   K K. Sen, “Sssc-static synchronous series compensator: Theory, modeling, and application”,IEEE Trans. Power Del., vol. 13, no. 1, pp. 241–246, Jan. 1998.

[3]   L.Gyugyi, C.D. Schauder, S. L.Williams, T. R. Rietman, D. R. Torgerson, and A. Edris, “The unified power flow controller: A new approach to power transmission control”, IEEE Trans. Power Del., vol. 10, no. 2, pp. 1085– 1097, Apr. 1995.

[4]   M. D. Deepak, E. B. William, S. S. Robert, K. Bill, W. G. Randal, T. B. Dale, R. I. Michael, and S. G. Ian, “A distributed static series compensator system for realizing active power flow control on existing power lines”, IEEE Trans. Power Del., vol. 22, no. 1, pp. 642–649, Jan.2007

[5]    M. Mohaddes, A. M. Gole, and S. Elez, “Steady state frequency response of statcom”, IEEE Trans. Power Del., vol. 16, no. 1, pp. 18–23, Jan. 2001.

Power Quality Improvement in Transmission Systems Using DPFCPower Quality Improvement in Transmission Systems Using DPFC

ABSTRACT

The flexible ac-transmission system (FACTS) family called distributed power flow controller (DPFC). The DPFC is derived from the unified power flow controller (UPFC) with eliminated common dc link. The active power exchange between the shunt and series converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third harmonic frequency. The DPFC is to use multiple small size single phase converters instead of large size three phase series converter in the UPFC. The large number of series converters provides redundancy, thereby increasing the system reliability. As the D-FACTS converters are single phase and floating with respect to the ground, there is no high voltage isolation required between the phases. The cost of the DPFC system is lower than the UPFC. The DPFC has the same control capability as the UPFC, which comprises the adjustment of the line impedance, the transmission angle, and the bus voltage. Due to the high control capability DPFC can also be used to improve the power quality and system stability, such as low frequency power oscillation damping, voltage sag restoration or balancing asymmetry.

KEYWORDS:

1.      AC–DC power conversion

2.      Load flow control

3.      Power electronics

4.      Power semiconductor devices

5.      Power system control

6.      Power-transmission control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1.DPFC configuration

EXPECTED SIMULATION RESULTS:

Figure 2.Supply voltage during sag condition

Figure 3. Injected voltage during sag condition

Figure 4. Elimination of sag voltage

Figure 5. Supply voltage during swell

Figure 6. Injected voltage for swell

Figure 7. Elimination of swell voltage

CONCLUSION

The series converter of the DPFC employs the DFACTS concept, which uses multiple small single-phase converters instead of one large-size converter. It is proved that the shunt and series converters in the DPFC can exchange active power at the third-harmonic frequency, and the series converters are able to inject controllable active and reactive power at the fundamental frequency. The DPFC is also used to improving power quality problems such as sag and swell. The reliability of the DPFC is greatly increased because of the redundancy of the series converters. The total cost of the DPFC is also much lower than the UPFC, because no high-voltage isolation is required at the series converter part and the rating of the components of is low.

REFERENCES

[1]   D. Divan and H. Johal, “Distributed facts-A new concept for realizing grid power flow control,” in IEEE 36th Power Electron. Spec. Conf. (PESC), 2005, pp. 8–14.

[2]    K K. Sen, “Sssc-static synchronous series compensator: Theory, modeling, and application”,IEEE Trans. Power Del., vol. 13, no. 1, pp. 241–246, Jan. 1998.

[3]    L.Gyugyi, C.D. Schauder, S. L.Williams, T. R. Rietman, D. R. Torgerson, and A. Edris, “The unified power flow controller: A new approach to power transmission control”, IEEE Trans. Power Del., vol. 10, no. 2, pp. 1085– 1097, Apr. 1995.

[4]    M. D. Deepak, E. B. William, S. S. Robert, K. Bill, W. G. Randal, T. B. Dale, R. I. Michael, and S. G. Ian, “A distributed static series compensator system for realizing active power flow control on existing power lines”, IEEE Trans. Power Del., vol. 22, no. 1, pp. 642–649, Jan.2007.

[5]   M. Mohaddes, A. M. Gole, and S. Elez, “Steady state frequency response of statcom”, IEEE Trans. Power Del., vol. 16, no. 1, pp. 18–23, Jan. 2001.