ISSN Vol.04,Issue.18, November-2016, Pages:

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1 ISSN Vol.04,Issue.18, November-2016, Pages: Power Quality Enhancement in BLDC Motor Drive Using Fuzzy Controller Based Bridge Less CUK Converter S. RAJESH 1, V. VEERA NAGI REDDY 2 1 PG Scholar, Dept of EEE, MJR College of Engineering and Technology, Piler, Chittoor A.P, India, rajesh.08230@gmail.com. 2 Asst. Professor, Dept of EEE, MJR College of Engineering and Technology, Piler, Chittoor A.P, India, vvnr352@gmail.com. Abstract: This paper presents a bridgeless Cuk converter-fed brushless DC (BLDC) motor drive for a cooling system. A new approach of speed control of BLDC motor is proposed by controlling the voltage at DC bus utilizing a single voltage sensor. The proposed drive uses a fuzzy controlled based working in inductor current mode (DICM) for the force component adjustment (PFC) and enhanced force quality (PQ) at the AC mains for an extensive variety of pace control. The bridgeless Cuk converter working in a DICM gives a natural PFC and requires a basic voltage supporter approach for the voltage control. The bridgeless converter topology is intended for getting the low conduction losses and requirement of low size of warmth sink for the switches. Keywords: BLDC, PFC, Cuk Converter, DICM. I. INTRODUCTION Attributable to high effectiveness, high torque/inertia ratio, high energy density, low support necessity and wide scope of pace control; brushless DC (BLDC) motors are getting to be prominent in numerous low and medium power applications. It is utilized as a part of numerous family sorts of hardware like fans, aeration and cooling systems, water pumps, fridges, clothes washers and so forth. BLDC engine has a three phase disseminated windings on the stator and lasting magnet in the rotor. As the name shows, it has no brushes for the compensation rather an electronic compensation is utilized in which Hall sensors are utilized for the rotor position detecting to determine the required compensation state utilizing a voltage source inverter (VSI). The BLDC motor encouraged by a diode bridge rectifier (DBR) with a high estimation of DC-link capacitor results in highly mutilated supply current and a poor element a power factor rectified (PFC) converter is required for getting the enhanced PQ at the AC mains for a VSI-fed BLDC motor drive. Two phase PFC converters have been in typical practice in which one converter is utilized for the PFC operation which is normally a support converter and other converter is utilized for the voltage control, choice of which relies on the sort of utilization. This has more losses because of result of higher number of segments and two switches. A single stage PFC converter has picked up prominence due to single stage operation which has diminished number of segments. A PFC and DC-link voltage control can be achieved in a single stage operation. Two basic methods of operation of a PFC converter, that is, continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are broadly utilized as a part of practice. In CCM or DCM, the inductor's current or the voltage crosswise over middle of the road capacitor in a PFC converter remains continuous or discontinuous in a switching period, separately. To work a PFC converter in CCM, one requires three sensors (two voltage, one current) while a DCM operation can be accomplished utilizing a single voltage sensor. The weights on PFC converter switch working in DCM are nearly higher as compared with its operation in CCM; subsequently decision of working mode is a exchange off between the reasonable anxiety and the force rating. A PFC boost half-bridge encouraged BLDC engine drive utilizing a four switch VSI has been proposed. This utilizes a steady DC-link voltage with PWM exchanging of VSI and have high switching losses. have proposed a PFC support converter encouraging a direct torque controlled (DTC)- based BLDC motor drive which requires higher number of sensors for DTC operation, have high switching losses. In PWM-VSI and expanded multifaceted nature of the control unit.a similar configuration using a front-end cascaded buck boost converter-fed BLDC motor have proposed a active PFC utilizing a single ended essential inductance converter (SEPIC) for feeding a BLDC motor drive which once more used a PWM-based VSI for rate control of BLDC motor which have switching losses corresponding to the exchanging recurrence of PWM pulses. A PFC Cuk converter working in CCM for feeding a BLDC engine drive has been proposed by Singh and Singh, however it requires three sensors for DC-link voltage control and PFC operation and subsequently this topology is suited for high-control applications. II. PROPOSED BRIDGELESS CUK A. Converter-Fed BLDC Motor Drive Fig. 1 demonstrates the proposed bridgeless Cuk converterfed BLDC motor driving an air conditioning compressor. The bridgeless Cuk converter is utilized to control the DC-link voltage (Vdc) of the VSI and to achieve a unity power component at AC mains. To eliminate a DBR in the front end, a bridgeless converter topology is utilized which has preference of low conduction losses and warm weight on the devices. Another methodology of speed control by controlling 2016 IJIT. All rights reserved.

2 the voltage at the DC link is utilized which uses a basic recurrence exchanging of VSI (i.e. electronic substitution of BLDC motor) consequently offers decreased switching losses. A voltage follower approach is utilized for the control of bridgeless Cuk converter working in spasmodic inductor current mode (DICM) in which a single voltage sensor is required for the detecting of DC-link voltage (Vdc). S. RAJESH, V. VEERA NAGI REDDY (2) Consequently the duty ratio for designed (ddes), greatest (dmax) and least (dmin) comparing to Vdcdes, Vdcmax and Vdcmin are computed utilizing (2) as , and , respectively. Now the nominal duty ratio (dnom) is taken not exactly ddes (planned obligation proportion) for an effective control in DICM, henceforth dnom is taken as 0.2. In the event that the measure of allowed swell current is ΔiLi (30% of Iin, where Iin = 2P/Vin = An) in both inductors Li1 and Li2, at that point the estimation of Li1 and Li2 is given as Fig. 1 proposed bridgeless Cuk converter-encouraged BLDC motor drive (3) Where Vm is the peak of supply voltage (i.e V), TS is the switching time frame (i.e 1/fS, where fs is the switching frequency = 20 khz). Subsequently, an estimation of 3 mh is chosen for inductor Li1 and Li2. The critical conduction parameter Kacrit is given as (4) Where M= Vdc/Vm and n is the turns proportion for isolated converter, (here n = 1 for non-isolated converter). Presently, the conduction parameter Ka for operation in DICM is to be taken as (5) The value of Ka is taken around two-thirds of Ka(critical) for an efficient control in DICM. Hence Ka is taken as Now, the equivalent inductance Leq is calculated as Fig.2. Operation of bridgeless Cuk converter for (a) positive & (2b) negative half cycle of supply voltage B. Design of bridgeless Cuk converter A bridgeless Cuk converter is designed for its operation in DICM to go about as a power factor (PF) pre-regulator with a wide voltage transformation proportion. In this mode, the input inductors (Li1 and Li2) and middle of the road capacitors (C1 and C2) are designed to work in nonstop conduction though; the current in output inductors (Lo1 and Lo2) gets to be broken in a complete exchanging period. A PFC converter of 500 W is intended for a 0.5 hp BLDC motor (full particulars are given in the index). For the supply voltage (Vs) of 220 V, the input average voltage Vinav is given as (6) Now the value of output side inductor (Lo1 and Lo2) is given as (7) Hence a value of 100 μh is selected to ensure a deep DICM condition (i.e. discontinuous conduction at very low duty ratio) to maintain a high-pf even at very low value of DC-link voltage. The capacitance of the energy transferring capacitors C1 and C2 is given as (1) The PFC bridgeless Cuk converter is intended for the DClink voltage control from 70 V (Vdcmin) to 310 V (Vdcmax) with a nominal value DC-link voltage as 190 V (Vdcdes). The duty proportion D, for a Cuk converter which is a buck boost converter topology is given as (8) Where ωr = 2πfr, fr is the resonant frequency of transitional capacitor (C1 and C2) and fs > fr > fl where fl is the line frequency. Subsequently for the line frequency and switching frequency of 50 and Hz, a resounding frequency of

3 Power Quality Enhancement in BLDC Motor Drive Using Fuzzy Controller Based Bridge Less CUK Converter 5000 Hz is chosen. Subsequently the estimation of capacitors C1 and C2 is chosen as 0.33 μf. The estimation of DC-link capacitor is given as (14) (9) Where Id is the DC-link current, ω is the line frequency in rad/s and ΔVdc is the permitted ripple voltage in DC-link capacitor which is taken as 1% of DC-link voltage. To avoid the reflection of high-order harmonics in supply system, a low-pass LC filter is designed. For a line frequency of 50 Hz, the cut-off frequency of filter is selected as 200 Hz. The maximum value of filter capacitance, Cfmax is given and calculated as (10) III. FUZZY CONTROL DESIGN Usually fuzzy logic control system is created from four major elements presented on Figure 2: fuzzification interface, fuzzy inference engine, fuzzy rule matrix and defuzzification interface. Each part along with basic fuzzy logic operations will be described in more detail below. Fig. 2. Fuzzy logic controller Compared with the sensed DC-link voltage to produce a voltage error signal to be fed in the rate controller. The reference voltage is generated by increasing the voltage constant (Kv) of the BLDC motor with the reference speed. A. Speed controller A voltage error signal is given to the rate controller which is a proportional integral controller for generating a controlled output for the PWM era stage. Whenever moment k, the voltage error signal Ve(k) and controller output Vc(k) is given as (12) (13) Where Kp and Ki represent the proportional and integral gain constants, respectively. B. PWM generator A fixed frequency, varying duty ratio PWM is generated by a PWM generator by comparing the controlled output of the speed controller with a high frequency saw-tooth generator Where Sw1 and Sw2 denote the switching signals as 1 and 0 for MOSFET Sw1 and Sw2 to switch on and off, respectively. C. Fuzzy logic Fuzzy logic is a complex mathematical method that allows solving difficult simulated problems with many inputs and output variables. Fuzzy logic is able to give results in the form of recommendation for a specific interval of output state, so it is essential that this mathematical method is strictly distinguished from the more familiar logics, such as Boolean algebra. D. Modelling of proposed drive system The modelling of a BLDC motor drive consists of a modelling of a BLDC motor, a VSI and an electronic commutation. E. BLDC motor The dynamic modelling of the BLDC motor is governed by following equations. Per phase voltage (Vxn, where x represents a, b or c and n represents neutral) are given as (15) (16) where p is the time differential operator, Rs speaks to resistance per phase, ix is the stage current, exn speaks to back emf, λx speaks to flux linkages, Vxo and Vno is potential distinction of a specific stage "x" and impartial "n" with the zero reference potential "o" which at the mid-point Of DC-link respectively as appeared in Fig. 3. The flux linkages are spoken to as Fig. 3. BLDC motor fed by a VSI (17) Where Ls is the self-inductance per phase and M is the mutual inductance of the windings. If x represents phase a, then y and z represent the phases b and c, respectively, and vice versa. Moreover for star connected three phase windings of the stator of BLDC motor (18) Hence by substituting (18) in (17) the flux linkages are obtained as (19)

4 Hence, the phase current derivative by using (15) and (19) are obtained as S. RAJESH, V. VEERA NAGI REDDY Moreover, the rotor position derivative of the BLDC motor is given as (20) The developed electromagnetic torque of the BLDC motor is given as (21) Where ωr is the rotor speed electrical rad/s.this expression for the torque confronts computational difficulty at zero speed as induced emfs are zero. Hence, it is reformulated by expressing back-emf as a function of rotor position angle θ, which can be written as (22) where kb is the back emf constant and fx(θ) are functions of rotor position having the trapezoidal shape as that of back-emf obtained in BLDC motor with a maximum magnitude of + or 1. The function fa(θ) corresponding to phase a is represented as (33) Hence, (20), (29) and (33) represent the time derivative of current, speed and rotor position and hence govern the dynamic model of a BLDC motor. Voltage source inverter The output of the VSI for phase a is given as Where Vdc represents the DC-link voltage and the on and off conditions for the IGBT s S1 and S2 are represented as 1 and 0, respectively. IV. RESULTS & DISCUSSION A. Supply voltage variation from 170 to 270 V Similarly the function fb(θ) and fc(θ) for phase b and c can be obtained by using a phase difference of 120 and 240, respectively. Now, substituting (22) into (21), the torque expression becomes Fig. 4. Supply voltage with PI The torque balance equation is given as (27) (28) Where Te is developed electromagnetic torque, TL is the load torque, B is the friction coefficient in N ms/rad, J is moment of inertia in kg m2 and P is the number of poles. Now (28) is used with (27) to obtain the time derivative of torque as (29) The potential of neutral terminal with respect to zero potential (Vno) is required to be considered in order to avoid unbalance in applied voltage. Substituting (16) in (15) and taking the sum for three phases, it results in Fig. 5. Supply current with PI Substituting (18) in (30) one obtains Thus (30) (31) (32) Fig. 6. Dc link voltage with PI

5 Power Quality Enhancement in BLDC Motor Drive Using Fuzzy Controller Based Bridge Less CUK Converter Fig. 7.Speed of the BLDC motor Drive with PI Fig. 12. Dc link voltage with PI Fig. 8. Electromagnetic torque with PI Fig. 13. Speed of the BLDC motor Drive with PI Fig. 9. Supply current with PI Fig. 14. Electromagnetic torque with PI B. Dynamic performance of the proposed bridgeless Cuk converter-fed BLDC motor drive during variation of DClink voltage Fig. 15. Stator current with PI Fig. 10. Supply voltage with PI C. Steady-state performance of the proposed bridgeless Cuk converter-fed BLDC motor drive (for DC-link voltage of 310 V) Fig. 11. Supply current with PI Fig. 16. Supply voltage with PI

6 S. RAJESH, V. VEERA NAGI REDDY Fig. 17. Supply current with PI Fig. 23. Switching stress voltagel with PI Fig. 18. Dc link voltage with PI Fig. 24. Switching stress current2 with PI Fig. 19. Speed of the BLDC motor Drive with PI Fig. 25. Switching stress voltage2 with PI Fig. 20. Electromagnetic torque with PI Fig. 26. Input inductor current1 with PI Fig. 21. Stator current with PI Fig. 27. Input inductor current2 with PI Fig. 22. Switching stress current with PI Fig. 28. Intermediate capacitor voltage1 with PI

7 Power Quality Enhancement in BLDC Motor Drive Using Fuzzy Controller Based Bridge Less CUK Converter Fig. 29. Intermediate capacitor voltage2 with PI Fig. 34. Dc link voltage with PI Fig. 30. Output inductor current1 with PI Fig. 34. Speed of the BLDC motor drive with PI Fig. 31. Output inductor current2 with PI Fig. 35. Electromagnetic torque with PI D. Steady-state performance of the proposed bridgeless Cuk converter-fed BLDC motor drive (for DC-link voltage of 70 V) Fig. 32. Supply voltage with PI Fig. 36. Stator current with PI Fig. 33. Supply current with PI Fig. 37. Switching stress current1 with PI

8 S. RAJESH, V. VEERA NAGI REDDY Fig. 38. Switching stress voltage1 with PI Fig. 43. Intermediate capacitor voltage1 with PI Fig. 39. Switching stress current2 with PI Fig. 44. Intermediate capacitor voltage2 with PI Fig. 40. Switching stress voltage2 with PI Fig. 45. Output inductor current1 with PI Fig. 41. Input inductor current1 with PI Fig. 46. Output inductor current2 with PI E. THD results Fig. 42. Input inductor current2 with PI

9 Power Quality Enhancement in BLDC Motor Drive Using Fuzzy Controller Based Bridge Less CUK Converter V. CONCLUSION In this paper a bridgeless PFC Cuk converter-encouraged BLDC motor drive system has been proposed for a ventilation system. Another plan of velocity control by controlling the voltage at the DC-connection of VSI utilizing a solitary voltage sensor has been proposed for a BLDC motor drive making it a financially savvy drive. An electronic replacement of BLDC motor has been utilized which uses a fundamental frequency switching of VSI consequently decreases the related switching misfortunes and speed. The front end PFC bridgeless Cuk converter working in DICM has been utilized for double operation of PFC and DC-link voltage control. The proposed drive system has kept up a high PF and enhanced PQ for a extensive variety of rate control and changing supply voltages. VI. REFERENCES [1] Kenjo, T., Nagamori, S.: Permanent magnet brushless DC motors (Clarendon Press, Oxford, 1985) [2] Gieras, J.F., Wing, M.: Permanent magnet motor technology design and application (Marcel Dekker Inc., New York, 2002) [3] Miller, T.J.E.: Brushless permanent magnet and reluctance motor drive (Clarendon Press, Oxford, 1989) [4] Handershot, J.R., Miller, T.J.E.: Design of brushless permanent magnet motors (Clarendon Press, Oxford, 2010) [5] Hanselman, D.C.: Brushless permanent magnet motor design (McGraw-Hill, New York, 2003) [6] Sokira, T.J., Jaffe, W.: Brushless DC motors: electronic commutation and control (Tab Books, USA, 1989) [7] Krishnan, R.: Electric motor drives: modeling, analysis and control (Pearson Education, India, 2001) [8]Toliyat, H.A.: Campbell S.: DSP-based electromechanical motion control (CRC Press, New York, 2004) [9] Limits for Harmonic Current Emissions (Equipment input current 16 A per phase), International Standard IEC , [10] Mohan, N., Undeland, T.M., Robbins, W.P.: Power electronics: converters, applications and design (John Wiley and Sons Inc, USA, 2009) Author Profile: Sri V.VeeraNagi Reddy, MJR College of Engineering and Technology (MJRCET), Piler, Chittoor (dt) A.P, India. He obtained masters degree from JNTU,Anantapur, India. Currently, he is working as HOD in electrical and electronics engineering department at MJRCET, A.P, INDIA. His research interests include Robotics, smart grids, distributed generation systems and renewable energy sources, power system operation and control.