Fuzzy Logic control of solar PV based BLDC motor driven for water pumping system employing with Cuk converter.

Transcription

1 Fuzzy Logic control of solar PV based BLDC motor driven for water pumping system employing with Cuk converter AUTHOR 1 Name : N. Anil Dattu M.tech 2nd year Institute of Aeronautical Engineering, Hyderabad, INDIA AUTHOR 2 HOD & GUIDE : Dr. P Sridhar (Professor & Head) QUALIFICATION : PH.D Department of Electrical and Electronics Engineering Institute of Aeronautical Engineering, Hyderabad, INDIA ABSTRACT This Paper explains about the design and control of PV array based BLDC Motor using CUK converter for the usage of irrigation and drinking water pumping system. Solar energy is defined as the conversion of sunlight in to electricity and it is an important source of renewable energy, Photovoltaic cells are used to absorb and convert the sunlight in to electricity. The maximum solar energy has been taken and utilized for powering the motor to water pumping system. For extracting the maximum power generated by photovoltaic array, CUK converter is used as maximum power point track with perturbation and observation method. With sudden changes in PV array power supply and also on the climatic variations CUK converter is operated either as a Buck or as a Boost. The CUK converter is fed to three phase inverter to provide proper supply to BLDC motor. The motor speed is controlled by adjusting the dc bus Voltage of Voltage source inverter (VSI). The fundamental frequency switching pulses are generated to operate the VSI in order to minimize the switching losses. In comparison with other motors, the BLDC Motor has a high power density, high efficiency, high torque/ inertia ratio and unity power factor. The performance of BLDC motor is studied under different operating conditions. In this project Fuzzy Page No:584

2 logic controller is used to generate pulses to the VSI for enhancing the efficiency of the system. Thus, the design and control of PV array based BLDC motor using CUK converter is modelling and simulation by using MATLAB/SIMULINK. Key Terms: PV, Cuk Converter, Fuzzy logic controller, BLDC motor. 1. INTRODUCTION Solar based photovoltaic (SPV) energy has developed as an elective wellspring of power era having quantities of points of interest. Also, the water pumping has turned into a cost powerful utilization of SPV energy now a days, particularly in remote areas and provincial territories1,2a threephase induction (IM) is generally utilized as a part of SPV exhibit nourished water pumping for water system and local purposes because of its appropriateness for applications in tainted and disconnected zones, minimal effort, unwavering quality and low support prerequisite3,4. A DC motor is additionally utilized as a part of5-7, yet attributable to a high upkeep necessity caused by the nearness of brushes and commutator, it is not favored for water pumping. Nonetheless, a confounded control of IM and high proficiency of a permanent magnet synchronous motor (PMSM) than an IM has persuaded the specialists to utilize a PMSM drive where a powerful submersible water pumping system is introduced. A few endeavours in the zone of SPV array fed water pumping utilizing a synchronous reluctance motor (SRM) have been made in the writing. It has been watched that the SRM can run satisfactorily for a constrained scope of solar oriented insolation level. Moreover, an exchanged reluctance motor (SRM) has likewise not gotten much consideration for SPV exhibit sustained water pumping till presently, most likely because of a high torque swell and acoustic commotion issue related with this drive. In the SRM is utilized in SPV exhibit based water pumping system also, satisfactorily operation even under the dynamic condition is guaranteed. On account of quantities of advantages of a permanent magnet brushless DC (BLDC) motor drive, for example, high productivity, long life, high unwavering quality, low radio frequency noise and no up keep different analysts are concentrating on this drive for SPV exhibit based water pumping thus picked in this work. A BLDC motor is utilized to drive the water draw in light of SPV array, which shows its reasonableness for water pumping. A DC- DC converter is regularly set between the Page No:585

3 SPV array and VSI (voltage source inverter) nourished BLDC motor pump with a specific end goal to track the ideal working purpose of the SPV array utilizing a most maximum power point tracking (MPPT) method. Fig. 1 presents a schematic diagram of the conventional BLDC motor drive for SPVwater pumping. The maximum power point tracking (MPPT) is performed by a DC DC converter. Two phase currents and a DC bus voltage are required to be sensed for motor control. The pulse width modulated (PWM) pulses operate a VSI, inviting the additional switching losses. A Z-source inverter (ZSI) replaces the DC DC converter, other components of Fig. 1 remaining unchanged, asserting a single-stage solution. However, the sensing of motor phase currents and DC bus voltage, and operation of the VSI in PWM mode are still required. In addition, the ZSI is unable to provide a soft starting to the BLDC motor with-out current control, which calls for the motor currents sensing. In order to resolve the aforementioned shortcomings, a cost-effective, simple and efficient photovoltaic (PV)-BLDC motor pumping system is proposed in this work as shown in Fig. 2. A Cuk converter is utilised for MPPT in various SPV pumping systems [27, 30]. Nonetheless, such a system with a BLDC motor drive is not precisely explored as of now with a Cuk converter. A Cuk converter- VSI-BLDC motor driven water pump powered by SPV array is reported in [27], however, no experimental study is carried out and it is demonstrated concisely only through a MATLAB/Simulink based simulation. Fig.1 Schematic diagram of conventional water pumping system. 2 WORKING PRINCIPLE OF PROPOSED SYSTEM The schematic graph of proposed topology is exhibited in Fig. 2.A Cuk converter is put between the PV exhibit and the VSI. The BLDC motor pump is fed by a VSI. The three inbuilt Hall sensors are utilized to produce the gating signals for VSI by methods for an electronic recompense. The electronic replacement alludes to commutating the currents moving through windings of BLDC motor in a predefined succession utilizing a decoder to such an extent that a symmetrical direct current is drawn from the DC bus of VSI for 120 and Page No:586

4 set in phase with back electro-motive force constrain (EMF).Additionally, the Cuk converter is worked for controlling the SPV exhibit through an incremental conductance (INC) MPPT procedure. It pressures the PV exhibit to be worked at maximum power point tracking (MPP) by relentlessly refreshing the duty ratio. As appeared in Fig. 2, the proposed BLDC motor drive wipes out the phase current sensors. In this manner, the speed is represented just by a variable DC bus voltage of VSI as the phase currents don't play any part in speed control. A variable DC bus voltage causes a variety in the output voltage of VSI (or information voltage to the motor) and henceforth in the motor speed. As the working point is moved towards MPP, by MPPT calculation, the duty ratio of Cuk converter increments bringing about a development of the DC bus voltage. This causes the BLDC motor to pivot and achieve certain speed relating to the connected DC voltage. The VSI is changed just to commutate the streams through the windings of BLDC engine by supposed electronic replacement. It doesn't take an interest in speed control. Fig. 2 Schematic diagram of proposed water pumping system. Rather, a greatness of the accessible DC bus voltage of VSI chooses the working velocity by controlling the size of its output voltage, like a square wave inverter which is exchanged at a crucial frequency. The DC bus voltage is reliably represented by MPPT through the duty ratio of Cuk converter. It fluctuates with an adjustment in climate profile; the speed is in this manner balanced appropriately. The control and plan of proposed topology are delineated in the further segments. 3 CONTROL APPROACH The control of proposed system is ordered into two noteworthy parts: Control of SPV cluster working point through a MPPT technique,and BLDC engine electronic replacement. These control approaches are examined as takes after. 3.1 Maximum power point tracking The MPPT approach in view of an INC is received to track an ideal point on the current voltage (Ipv Vpv) attributes of Page No:587

5 the sunlight based PV exhibit. This strategy investigates that the power incline of a PV cluster attributes is invalid at MPP (dppv/dvpv = 0), negative at right of MPP and positive at left of MPP. Along these lines, an ideal working point is inferred in light of an INC as The duty ratio, D is perturbed with fixed perturbation size and rate according to the power slope until the operating point of solar PV array reaches MPP. The tracking is started with an initial value of the duty cycle as zero. This leads to a soft starting of the motor by reducing the rate of rise of DC bus voltage. 3.2 Fuzzy logic control FLC has two inputs and one output. These are error (e), error change (de) and control signal, respectively. Linguistic variables which implies inputs and output have been classified as: NB, NM, NS, Z, PS, PM, PB. Inputs and output are all normalized in the interval of [-10,10] as shown in Fig. 5 Figure 5. Membership functions of output In view of the simplicity, a duty ratio control is adopted to realise the INC-MPPT. This method directly uses duty cycle, D as the control parameter. The two input fuzzy controller with coupled rules formed by combining both PI and PD actions. The linguistic labels used to describe the Fuzzy sets were Negative Big (NB), Negative Medium (NM), Negative Small (NS), Zero (Z), Positive Small (PS), Positive Medium (PM), Positive Big (PB). It is possible to assign the set of decision rules as shown in Table IV. The fuzzy rules are extracted from fundamental knowledge and human Page No:588

6 experience about the process. These rules contain the input/the output relationships that define the control strategy. Each control input has seven fuzzy sets so that there are at most 49 fuzzy rule. TABLE IV. TABLE OF FUZZY RULE CE E NB NM NS Z PS PM PB NB NB NB NB NB NM NS Z NM NB NB NB NM NS Z PS NS NB NB NM NS Z PS PM Z NB NM NS Z PS PM PB PS NM NS Z PS PM PB PB PM NS Z PS PM PB PB PB PB Z PS PM PB PB PB PB 3.3 Electronic commutation of BLDC motor By methods for an electronic replacement, a symmetrical direct current is drawn from the high at any moment, bringing about a low conduction losses. The essential frequency switching of VSI, in correlation with a highfrequency PWM switching, offers a few advantages regarding effectiveness, execution and the switching gadget usage. A higher switching frequency implies more prominent power losses, requesting derating of the switching gadgets, and more board space or a warmth sink to disperse the warmth. Additionally, the electro-attractive impedance can be tricky to the engine execution while working at high switching frequency. As the switching losses rely upon the connected DC transport voltage and switching frequency, it shifts with a variety in the working conditions. In this manner, the losses are additionally lessened under terrible climate profile. DC connection of VSI for 120 and set at the focal point of back-emf. The three Hall sensors create an arrangement of Hall signals (H1 H3) at an interim of 60 as per the rotor position [6, 9,11], as appeared in Table 2. Utilizing a decoder, these signs are changed into the six essential frequency beats (S1 S6),which choose the switching conditions of VSI. Just two heartbeats are 4 SYSTEM DESIGN A suitable plan and particulars of BLDC motor pump, SPV exhibit and Cuk converter assume a huge part in the coveted task of a water pump. A six-shaft BLDC engine with 3000 rpm and 5.8 kw is chosen. The PV cluster, Cuk converter and water pump are chosen with the end goal that working of the system isn't hindered under any unsettling influence in the air conditions. Page No:589

7 4.1 PV cluster outline A SPV cluster with a pinnacle energy of 6.8 kw is intended for a 5.8 kw motor pump because of the way that marginally overabundance control must be created by an exhibit keeping in mind the end goal to remunerate the converters and engine control losses. HB-12100, a HBL Power System Ltd. PV module, is considered for the outline of a cluster. At 1000 W/m2,the determinations of HB and the parameters of an outlined cluster are said in Table 3. parameters of Cuk converter is summarised in Table 4. Table 4 Cuk converter design: 4.2 Design of Cuk converter The Cuk converter is designed such that it operates in a continuous conduction mode (CCM) regardless of the climatic conditions. According to the climatic variations, the converter is operated either as a buck or a boost converter. Estimation of the All the parameters are calculated at an irradiance level of 1000 W/m2. As a dropoff in their radiance occurs, the currents flowing through both inductors are reduced. This causes an increase of ripple contents in the inductor currents. However, the duty ratio and PV array voltage are also reduced simultaneously, resulting in a suppressed ripple. Thus, the reduced inductor current leads to an increase in ripple content only by small amount, as a resultant reduction caused by the duty ratio and PV array voltage is somewhat less than a reduction in the inductor current. Ultimately, the CCM operation is retained. Contrary to it, as the Page No:590

8 reduction in a PV array current is more than the reduction in a voltage across the energy transfer capacitor, a drop-off in the irradiance causes a significant reduction of ripple contents in the voltage. Therefore, the capacitor voltage becomes further continuous. In this fashion, CCM operation of the converter is ensured regardless of the operating conditions. The inductors of 5 MH are justifiable in a selected range of voltage and power (289 V, 6.8 kw) for the system design. The lower value scan also serve the purpose, but there are following trade-offs due to increased ripple content on the inductor currents: The peak current stress on the power devices increases, the devices with higher current rating are thereby required. The core magnetic hysteresis losses are increased. In addition, the AC winding losses due to skin effect and proximity effect become more significant. The RMS current flowing through the inductor increases, which results in an increased I2R losses followed by the inductor temperature rise. Therefore, the selected inductors lead to a significant reduction in the power losses (especially in the selected power range), and the power devices with a reduced current rating. These features are indeed required in the proposed system. 4.3 Water pump design A centrifugal pump, coupled to the shaft of BLDC motor, is used as a water pump in the proposed system. It is modelled and designed to operate at its rated speed and power such that a full volume of wateris delivered under the standard atmospheric condition. The torque speed relationship of a centrifugal pump is given as [25] The first term (square torque speed relationship) in (6) is derived from the power equation of the affinity laws, which is represented by (7). The factors k1, k2, k3 depend on the discharge valve settings. In general, the lower order terms are neglected at high speed. The second and third terms in (6) together represent a breakaway torque, required to overcome the static friction to start the centrifugal pump. These terms, respectively, denote the transition from static to kinetic friction, and Coulomb friction. It is assumed that the effect of these frictions vanishes as the pump attains a certain speed (10 20% of rated). Thus, the centrifugal pump is Page No:591

9 approximately designed using the pump affinity laws which endorses a square torque speed or a cubic power speed relationship as (b)torque 5. SIMULATION RESULTS (c)dc link voltage (d)line to line voltage simulation circuit (a)rotor speed 6 CONCLUSION The proposed PV-water pumping plan has been approved through a show of its different unfaltering state, beginning and dynamic exhibitions. The execution of the system has been recreated utilizing the Page No:592

10 MATLAB tool compartments, and actualized on an exploratory system. The DC link voltage and motor phase current detecting components have been completely wiped out, bringing about a basic and financially savvy drive. The VSI has embraced a basic frequency switching, offering an improved productivity because of the diminished switching losses in VSI. The other wanted capacities are speed control through factor DC link voltage with no extra circuit and a delicate beginning of the motor pump. The Cuk converter has given an unbounded MPPT district and nonthrobbing streams, wiping out the swell channels. The definite similar investigation of the proposed and the current work have eventually showed the predominance of the proposed system. policies, IET Renew. Power Gener., 2016, 10, (1), pp Hirth, L.: Market value of solar power: is photovoltaics cost-competitive, IET Renew. Power Gener., 2015, 9, (1), pp Mapurunga Caracas, J.V., De Carvalho Farias, G., Moreira Teixeira, L.F., et al.: Implementation of a high-efficiency, high-lifetime, and low-cost converter foran autonomous photovoltaic water pumping system, IEEE Trans. Ind. Appl.,2014, 50, (1), pp Hwang, C.C., Li, P.L., Liu, C.T., et al.: Design and analysis of a brushless DC motor for applications in robotics, IET Electr. Power Appl., 2012, 6, (7),pp REFERENCES 1 Vithayasrichareon, P., Mac Gill, I.F.: Valuing large-scale solar photovoltaics in future electricity generation portfolios and its implications for energy and climate Page No:593