An Intelligent Fuzzy Sliding Mode Controller for aBLDC Motor

ABSTRACT:  

Brushless DC (BLDC) motors are one of the most widely used motors, not only because of their efficiency, and torque characteristics, but also because they have the advantages of being a direct current (DC) supplied, eliminating the disadvantages of using Brushes. BLDC motors have a very wide range of speed, so speed control is a very important issue for it. Sliding mode control (SMC) is one of the popular strategies to deal with uncertain control systems. The Fuzzy Sliding Mode Controller (FSMC) combines the intelligence of a fuzzy inference system with the sliding mode controller. In this paper, an intelligent Fuzzy Sliding Mode controller for the speed control of BLDC motor is proposed. The mathematical model of the BLDC motor is developed and it is used to examine the performance of this controller. Conventionally PI controllers are used for the speed control of the BLDC motor. When Fuzzy SMC is used for the speed control of BLDC motor, the peak overshoot is completely eliminated which is 3% with PI controller. Also the rise time is reduced from 23 ms to 4 ms and the settling time is reduced from 46 ms to 4 ms by applying FMSMC. This paper emphasizes on the effectiveness of speed control of BLDC motor with Fuzzy Sliding Mode Controller and its merit over conventional PI controller.

KEYWORDS:

  1. BLDC motors
  2. Sliding Mode Control
  3. Fuzzy Sliding Mode controller
  4. PI Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig 1 Block diagram of BLDC speed control.

EXPECTED SIMULATION RESULTS:

 

Fig 2 Step response with Fuzzy SMC and Fuzzy PI and PI Controllers

Fig 3 Current in the three phases

 

CONCLUSION:

 Fuzzy sliding mode controller for the speed control of BLDC motor is designed and its performance comparison with PI controller is carried out in this paper. Conventionally PI controllers are used for the speed control of BLDC motor and they give moderate performance under undisturbed conditions even though they are very simple to design and easy to implement. But their performance is poor under disturbed condition like sudden changes in reference speed and sudden change in load. The BLDC motor with PI controller shows large overshoot, high settling time and comparatively large  speed variation under loaded condition.

The Fuzzy Sliding Mode Controller combines the intelligence of fuzzy logic with the Sliding Mode technique. The peak overshoot is completely eliminated and the rise time and settling time are improved when Fuzzy SMC is applied for the speed control of BLDC motor. The fluctuation in speed of the motor under loaded condition is also reduced when fuzzy SMC is applied. Thus this controller becomes an ideal choice for applications where very precise and fine control is required.

REFERENCES:

[1] Neethu U., Jisha V. R., “Speed Control of Brushless DC Motor : A Comparative Study”, IEEE International Conference on Power  Electronics, Drives and Energy Systems, Vol. 8, No. 12, 16-19 December 2012, Bengaluru India.

[2] Chee W. Lu, “T orque Controller for Brushless DC Motors”, IEEE Transactions on Industrial Electronics, Vol. 46, No. 2, April 1999.

[3] Tony Mathew, Caroline Ann Sam, ”Closed Loop Control of BLDC Motor Using a Fuzzy Logic Controller and Single Current Sensor”, International Conference on Advanced Computing and Communication Systems (ICACCS), Vol. 2, No. 13, 19-21 December 2013, Coimbatore India.

[4] T . Raghu, S. Chandra Sekhar, J. Srinivas Rao,“SEPIC Converter based – Drive for Unipolar BLDC Motor”, International Journal of Electrical  and Computer Engineering (IJECE), Vol.2, No.2, April 2012, pp. 159- 165.

[5] M. A. Jabbar, Hla Nu Phyu, Zhejie Liu, Chao Bi, “Modelling and Numerical Simulation of a Brushless Permanent – Magnet DC Motor in Dynamic Conditions by Time – Stepping T echnique”, IEEE Transactions on Industry Applications, Vol. 40, no. 3, MAY/JUNE 2004.

Sliding Mode Control Methods Time-Varying and Constant Switching Frequency Based Trans- former less DVR Employing Half-Bridge VSI

sliding mode control  IEEE Transactions on Industrial Electronics, 2016

 ABSTRACT:

sliding mode control This paper presents time-varying and constant switching frequency based sliding mode control (SMC) methods for three-phase transformerless dynamic voltage restorers (TDVRs) which employ half-bridge voltage source inverter (VSI). An equation is derived for the time-varying switching frequency. However, since the time-varying switching frequency is not desired in practice, a smoothing operation is applied to the sliding surface function within a narrow boundary layer with the aim of eliminating the chattering effect and achieving a constant switching frequency operation. The control signal obtained from the smoothing operation is compared with a triangular carrier signal to produce the PWM signals. The feasibility of both SMC methods has been validated by experimental results obtained from a TDVR operating under highly distorted grid voltages and voltage sags. The results obtained from both methods show excellent performance in terms of dynamic response and low total harmonic distortion (THD) in the load voltage. However, the constant switching frequency based SMC method not only offers a constant switching frequency at all times and preserves the inherent advantages of the SMC, but also leads to smaller THD in the load voltage than that of time-varying switching frequency based SMC method.

 

KEYWORDS:

  1. Constant switching frequency
  2. Dynamic voltage restorer
  3. Sliding mode control
  4. Time-varying switching frequency.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of three-phase TDVR with the proposed SMC methods. (a) Time-varying switching frequency based SMC method, (b) Constant switching frequency based SMC method.

 

EXPECTED SIMULATION RESULTS:.

Fig.2. Simulated responses of sk v , se k v , and Lk v obtained by the constant switching frequency based SMC under three-phase-to-ground fault. (a) sk v , (b) se k v , and (c)Lk v .

Fig. 3. Simulated responses of vsk , se k v , and Lk v obtained by the constant switching frequency based SMC under single-phase-to-ground fault. (a)sk v , (b) se k v , and (c)Lk v .

 

Fig. 4. Simulated responses of sk v , se k v , and Lk v obtained by the SMC method presented in [15]. (a) sk v , (b) se k v , and (c) Lk

 

Fig. 5. Simulated responses of sk v , se k v , and Lk v obtained by the time-varying switching frequency based SMC. (a) sk v , (b) se k v , and (c)Lk v .

Fig. 6. Simulated responses of sk v , se k v , and Lk v obtained by the constant switching frequency based SMC. (a) sk v , (b) se k v , and (c)Lk v .

 

CONCLUSION:

In this study, time-varying and constant switching frequency based SMC methods are presented for three-phase TDVR employing half-bridge VSI. An analytical equation is derived to compute the time-varying switching frequency. Since, the time-varying switching frequency is not desired in a real application, a smoothing operation is applied to the sliding surface function within a narrow boundary layer with the aim of eliminating the chattering effect and achieving a constant switching frequency. The control signal obtained from the smoothing operation is compared with a triangular carrier signal to produce the PWM signals. It is observed that the smoothing operation results in a constant switching frequency operation at all times. The feasibility of both SMC methods has been validated by experimental results obtained from the TDVR operating under highly distorted grid voltages and voltage sags. The results obtained from both methods show excellent performance. However, the constant switching frequency based SMC method not only offers a constant switching frequency at all times and preserves the inherent advantages of the SMC, but also leads to smaller THD in the load voltage than that of time-varying switching frequency based SMC method.

 

REFERENCES:

  • Bollen, Understanding Power Quality Problems. New York, NY, USA: IEEE Press, 2000.
  • Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques. West Sussex, United Kingdom: John Wiley & Sons Inc., 2015.
  • W. Li, F. Blaabjerg, D. M. Vilathgamuwa, and P. C. Loh, ”Design and comparison of high performance stationary-frame controllers for DVR implementation,” IEEE Trans. Power Electron., vol. 22, no. 2, pp. 602-612, Mar. 2007.
  • Kim, and S. K. Sul, ”Compensation voltage control in dynamic voltage restorers by use of feed forward and state feedback scheme,” IEEE Trans. Power Electron., vol. 20, no. 5, pp. 1169-1177, Sep. 2005.

Direct Power Control of Series Converter of Unified Power-Flow Controller With Three-Level Neutral Point Clamped Converter

 

ABSTRACT:

A unified power-flow controller (UPFC) can enforce unnatural power flows in a transmission grid, to maximize the power flow while maintaining stability. Theoretically, active and reactive power flow can be controlled without overshoot or cross coupling. This paper develops direct power control, based on instantaneous power theory, to apply the full potential of the power converter. Simulation and experimental results of a full three-phase model with nonideal transformers, series multilevel converter, and load confirm minimal control delay, no overshoot nor cross coupling. A comparison with other controllers demonstrates better response under balanced and unbalanced conditions. Direct power control is a valuable control technique for a UPFC, and the presented controller can be used with any topology of voltage-source converters. In this paper, the direct power control is demonstrated in detail for a third-level neutral point clamped converter.

KEYWORDS:

  1. Direct power control
  2. Flexible ac transmission control (FACTS)
  3. Multilevel converter
  4. Sliding mode control
  5. Unified power-flow controller (UPFC)

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. One-wire schematic of the transmission line with UPFC.

 EXPECTED SIMULATION RESULTS:

 Fig. 2. UPFC series converter controlling power flow under balanced conditions, 2.5-s view during stepwise changes of active and reactive power flow reference Pref , Qref. (a) Simulation ( P 948 Wpu, Q 948 VArpu) ( ia,ib ,ic 2.38 Apu). (b) Experimental (CH1: P 40 W/V, CH2: Q 40 VAr/V, 5 V/div) (CH3, CH4: ia,ib 0.22 A/V, 5 V/div). (c) Simulation ( P 948 Wpu, Q 948 VArpu) ( ia, ib,ic 2.38 Apu). (d) Experimental (CH1:P  40W/V, CH2: Q 40 VAr/V, 5 V/div) (CH3,CH4: ia,ib 0.22 A/V, 5 V/div).

Fig. 3. UPFC series converter controlling the power flow under balanced conditions, 250-ms view during stepwise change of active and reactive power flow reference Pref, Qref. (a) Simulation ( P 948Wpu, Q 948 VArpu) ( USa,USb ,USc 230 Vpu) ( ia, ib, ic2.38 Apu). (b) Experimental, (CH1: P 40 W/V, CH2: Q 40 VAr/V, 5 V/div)(CH3,CH4:ia , ib 0.22 A/V, 5 V/div). (c) Simulation ( P 948Wpu, Q 948 VArpu) (USa ,USb ,USc 230 Vpu) ( ia,ib ,ic 2.38 Apu). (d) Experimental, (CH1: P 40 W/V, CH2: Q 40 VAr/V, 5 V/div) (CH3,CH4: ia,ib 0.22 A/V, 5 V/div).

F ig. 4. UPFC series converter controlling power flow, comparison between controllers DPC (-) ADC(- -) [5] DIC (-.) [21]. (a) Simulation under balanced conditions, simultaneous step in active and reactive power references Pref, ,Qref 250-ms view ( P 948Wpu, Q 948 VArpu). (b) Simulation under balanced conditions, simultaneous step in active and reactive power references Pref, ,Qref, 6 ms view ( P 948 Wpu, Q 948 VArpu). (c) Simulation under unbalanced conditions, 70% single-phase voltage sag at 0.125 s, 250-ms overview (P 948 Wpu, Q 948 VArpu) ( USa, USb, USc 230 Vpu).

CONCLUSION:

The DPC technique was applied to a UPFC to control the power flow on a transmission line. The technique has been described in detail and applied to a three-level NPC converter. The main benefits of the control technique are fast dynamic control behavior with no cross coupling or overshoot, with a simple controller, independent of nodal voltage changes. The realization was demonstrated by simulation and experimental results on a scaled model of a transmission line. The controller was compared to two other controllers under balanced and unbalanced conditions, and demonstrated better performance, with shorter settling times, no overshoot, and indifference to voltage unbalance. We conclude that direct power control is an effective method that can be used with UPFC. It is readily adaptable to other converter types than the three-level converter demonstrated in this paper.

REFERENCES:

[1] L. Gyugyi, “Unified power-flow control concept for flexible ac transmission systems,” Proc. Inst. Elect. Eng., Gen., Transm. Distrib., vol. 139, no. 4, pp. 323–331, Jul. 1992.

[2] L. Gyugyi, C. Schauder, S.Williams, T. Rietman, D. 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.

[3] X. Lombard and P. Therond, “Control of unified power flow controller: Comparison of methods on the basis of a detailed numerical model,” IEEE Trans. Power Syst., vol. 12, no. 2, pp. 824–830, May 1997.

[4] H. Wang, M. Jazaeri, and Y. Cao, “Operating modes and control interaction analysis of unified power flow controllers,” Proc. Inst. Elect. Eng., Gen., Transm. Distrib., vol. 152, no. 2, pp. 264–270, Mar. 2005.

[5] H. Fujita, H. Akagi, and Y. Watanabe, “Dynamic control and performance of a unified power flow controller for stabilizing an ac transmission system,” IEEE Trans. Power Electron., vol. 21, no. 4, pp. 1013–1020, Jul. 2006.

Fixed Switching Frequency Sliding Mode Control for Single-Phase Unipolar Inverters

ABSTRACT:
Sliding mode control (SMC) is recognized as robust controller with a high stability in a wide range of operating conditions, although it suffers from chattering problem. In addition, it cannot be directly applied to multi switches power converters. In this paper, a high performance and fixed switching frequency sliding mode controller is proposed for a single-phase unipolar inverter. The chattering problem of SMC is eliminated by smoothing the control law in a narrow boundary layer, and a pulse width modulator produces the fixed frequency switching law for the inverter. The smoothing procedure is based on limitation of pulse width modulator. Although the smoothed control law limits the performance of SMC, regulation and dynamic response of the inverter output voltage are in an acceptable superior range. The performance of the proposed controller is verified by both simulation and experiments on a prototype 6-kVA inverter. The experimental results show that the total harmonic distortion of the output voltage is less than 1.1% and 1.7% at maximum linear and nonlinear load, respectively. Furthermore, the output dynamic performance of the inverter strictly conforms the standard IEC62040-3. Moreover, the measured efficiency of the inverter in the worst condition is better than 95.5%.
KEYWORDS:
1. Pulse width modulator
2. Sliding mode control
3. Unipolar single phase inverter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed controller for single-phase inverters with a resonator in voltage loop.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation result. a) Output voltage and current at 6-kW linear load. b) Output voltage and current at 6-kVA nonlinear load with CF = 2.75 and PF = +0.7.

Fig. 3. Simulation result: transient response of the output voltage for linear step load from zero to 100%

Fig. 4. Simulation result: transient response of the output voltage for linear
step load from 100% to zero.

Fig. 5. Experimental result: efficiency of inverter versus output power.

CONCLUSION:
In this paper, a fixed frequency SMC was presented for a single-phase inverter. The performance of the proposed controller has been demonstrated by a 6-kVA prototype. Experimental results show that the inverter is categorized in class1 of the IEC64020-3 standard for output dynamic performance. The inverter efficiency was measured up to 95.5% in the worst case.

Since the direct SMC cannot be applied to four switches unipolar inverter and it also suffers from the chattering problem, a PWM is employed to generate a fixed frequency switching law. The PWM modulates the smoothed discontinuous control law which is produced by SMC. To smooth the control law, the limitation of the PWM was considered.

The simulation and experimental results show that the load regulation is about 1% at the steady state as well. But, to obtain better regulation, a resonance compensator was added in the voltage loop. With this compensator, the load regulation was measured which has been below 0.2%.

REFERENCES:
[1] G. Venkataramanan and D.M. Divan, “Discrete time integral sliding mode control for discrete pulse modulated converters,” in Proc. 21st Annu. IEEE Power Electron. Spec. Conf., San Antonio, TX, 1990, pp. 67–73.
[2] J.Y.Hung,W. Gao, and J. C.Hung, “Variable structure control:Asurvey,” IEEE Trans. Ind. Electron., vol. 40, no. 1, pp. 2–22, Feb. 1993.
[3] E. Fossas and A. Ras, “Second order sliding mode control of a buck converter,” in Proc. 41st IEEE Conf. Decision Control, 2002, pp. 346– 347.
[4] C. Rech, H. Pinheiro, H. A. Gr¨undling, H. L. Hey, and J. R. Pinheiro, “A modified discrete control law for UPS applications,” IEEE Trans. Power Electron., vol. 18, no. 5, pp. 1138–1145, Sep. 2003.
[5] K. S. Low, K. L. Zhou, and D.W.Wang, “Digital odd harmonic repetitive control of a single- phase PWM inverter,” in Proc. 30th Annu. Conf. IEEE Ind. Electron. Soc., Busan, Korea, Nov. 2–6, 2004, pp. 6–11.

 

 

Indirect Vector Control of Induction Motor Using Sliding-Mode Controller

 

ABSTRACT:

The paper presents a sliding-mode speed control system for an indirect vector controlled induction motor drive for high performance. The analysis, design and simulation of the sliding-mode controller for indirect vector control induction motor are carried out. The proposed sliding-mode controller is compared with PI controller with no load and various load condition. The result demonstrates the robustness and effectiveness of the proposed sliding-mode control for high performance of induction motor drive system.

 KEYWORDS:

  1. Indirect vector control
  2. Sliding mode control
  3. PI controller
  4. Induction motor
  5. Speed control

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

image001

Figure 1: Indirect vector controlled induction motor drive

EXPECTED SIMULATION RESULTS:

 image002

Figure 2: Speed response of PI controller at no load

image003

Figure 3:Speed response of Sliding-mode controller at no load

image004

Figure 4: Speed response of PI controller at load

image005

Figure 5: Speed response of Sliding- mode controller at load

image006

Figure 6:X-Y plot of Rotor flux of PI controller

image007

Figure 7: x-v plot of Rotor flux of Sliding-mode controller

CONCLUSION:

In this paper sliding-mode controller for the control of an indirect vector-controlled induction motor was described. The drive system was simulated with sliding-mode controller and PI controller and their performance was compared. Here simulation results shows that the designed sliding-mode controller realises a good dynamic behaviour of the motor with a rapid settling time, no overshoot and has better performance than PI controller. Sliding-mode control has more robust during change in load condition.

.REFERENCES:

[1] B.K Bose “Modern power electronics and ac drives “Prentice-Hall OJ India, New Delhi, 2008.

[2] M.Masiala;B.Vafakhah,;A.Knght,;J.Salmon,;”Performa nce of PI and fuzzy logic speed control of field-oriented induction motor drive,” CCECE , jul. 2007, pp. 397-400.

[3] F.Barrero;A.Gonzalez;A.Torralba,E.Galvan,;L.G.Franqu elo; “Speed control of induction motors using a novel Fuzzy-sliding mode structure,”IEEE Transaction on Fuzzy system, vol. 10, no.3, pp. 375-383, Jun 2002.

[4] H.F.Ho,K.W.E.Cheng, “position control of induction motor using indirect adaptive fuzzy sliding mode control,” P ESA, , Sep. 2009, pp. 1-5.

[5] RKumar,R.A.Gupta,S.V.Bhangale, “indirect vector controlled induction motor drive with fuzzy logic based intelligent controller,” IETECH Journals of Electrical Analysis, vol. 2, no. 4, pp. 211-216, 2008.