Varying Phase Angle Control In Isolated Bidirectional DC–DC Converter For Integrating Battery Storage And Solar PV System In Standalone Mode

ABSTRACT:

This study proposes a varying phase angle control (VPAC) in isolated bidirectional dc–dc converter (IBDC) for integrating battery storage unit to a DC link in a standalone solar photovoltaic (PV) system. The IBDC is capable of power transfer using high step up/down ratio between DC link and battery. The VPAC control proposed in this study effectively manage the power flow control between the battery storage unit and the solar PV fed DC link by continuously varying the phase angle between high voltage and low voltage (LV) bridge voltage of the IBDC. The solar PV system is incorporated with the maximum power point tracking using DC–DC converter. In order to control the voltage across the AC load a voltage source inverter is used. The study also presents the design aspects of the IBDC converter for the application considered. The performance of the proposed power flow control strategy has been studied through PSCAD/EMTDC simulation and validated using LPC 2148 ARM processor.

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1 Block diagram for proposed standalone system

(a) Generalised block diagram, (b) Mode 1 operation, (c) Mode 2 operation, (d) Mode 3 operation

EXPECTED SIMULATION RESULTS:

 

 Fig. 2 Simulation results of IBDC

(a) Battery current during change in mode 1 to mode 2, (b) Battery current during change in mode 2 to mode 1, (c) Solar PV power, load power and battery power during change in mode 1 to mode 2, (d) Solar PV power, load power and battery power during change in mode 2 to mode 1

 CONCLUSION: 

The proposed variable phase angle control of IBDC converter balances the power flow between the solar PV system, battery storage unit and AC load in all the modes. The VPAC algorithm ensures that the, (i) solar PV system delivers maximum demanded power corresponding to the load and battery gets charged/ discharged through the available excess/short power. The governing mathematical formulation of problem reveals the dependency of average battery current on phase angle between the voltages of LV and HV side of the IBDC converter and hence provides a strategy to control the power flow. The analysis presented can be used to design the passive components and switches of the IBDC. From the obtained results, the performance of the proposed VPAC has been established with smooth transition of power flow between the PV fed DC link and the battery through the IBDC converter. The maximum power is extracted from the solar PV and AC load voltage is controlled in all the modes.

REFERENCES:

[1] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89, (8), pp. 1216–1226

[2] Solodovnik, E.V., Liu, S., Dougal, R.A.: ‘Power controller design for maximum power tracking in solar installations’, IEEE Trans. Power Electron., 2004, 19, (5), pp. 1295–1304

[3] Kuo, Y.-C., Liang, T.-J., Chen, J.-F.: ‘Novel maximum-power-point tracking controller for photovoltaic energy conversion system’, IEEE Trans. Ind. Electron., 2001, 48, (3), pp. 594–601

[4] Koutroulis, E., Kalaitzakis, K., Voulgaris, N.C.: ‘Development of a microcontroller-based, photovoltaic maximum power point tracking control system’, IEEE Trans. Power Electron., 2001, 16, (1), pp. 46–54

 

Direct Torque Control using Switching Table forInduction Motor Fed by Quasi Z-Source Inverter

ABSTRACT:

 Z-source inverters eliminate the need for front-end DC-DC boost converters in applications with limited DC voltage such as solar PV, fuel cell. Quasi Z-source inverters offer advantages over Z-source inverter, such as continuous source current and lower component ratings. In this paper, switching table based Direct Torque Control (DTC) of induction motor fed by quasi Z-Source Inverter (qZSI) is presented. In the proposed technique, dc link voltage is boosted by incorporating shoot through state into the switching table. This simplifies the implementation of DTC using qZSI. An additional DC link voltage hysteresis controller is included along with torque and flux hysteresis controllers used in conventional DTC. The results validate the boost capability of qZSI and torque response of the DTC.

KEYWORDS:

  1. DTC
  2. QZSI
  3. DC-DC Converter
  4. DC Link Voltage
  5. Hysteresis Controller

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

Fig. 1: Block Diagram for DTC using qZSI

EXPECTED SIMULATION RESULTS:

 Fig.2: Torque vs. Time

Fig. 3: Stator Phase ‘a’ Current

Fig. 4: Speed vs. Time

 

Fig. 5: DC Link Voltage

Fig. 6: Capacitor Voltage, VC1

 CONCLUSION:

 In this paper, direct torque control of induction motor fed by qZSI is presented. Dynamic torque response for step change obtained is 3 ms, which is needed for high performance applications. qZSI provides a single stage solution for drives with variable input DC voItage, instead of DC-DC converter cascaded with 3-leg inverter bridge. This paper presents a solution for drives with lesser DC input voItage availability and also requiring very fast torque response. The results shows that by introducing shoot through state in switching table of direct torque control, DC link voItage in qZSI is boosted. The DC link voItage hysteresis controller uses the input and capacitor voItage for controlling DC link voItage. If there is any disturbance in input voItage, the reference for capacitor voItage will be changed accordingly to maintain the DC link voItage.

REFERENCES:

 [I] 1. Takahashi and Y. Ohmori, “High-performance direct torque control of an induction motor, ” IEEE Trans. Ind. Appl., vol. 25, no. 2, pp. 257-264, 1989.

[2] B.-S. Lee and R. Krishnan, “Adaptive stator resistance compensator for high performance direct torque controlled induction motor drives, ” in Industry Applications Conference, 1998. Thirty-Third lAS Annual Meeting. The 1998 IEEE, vol. I, Oct 1998, pp. 423-430 voLl.

[3] G. Buja and M. Kazmierkowski, “Direct torque control of pwm inverter-fed ac motors-a survey, ” IEEE Trans. Ind. Electron., vol. 51, no. 4, pp. 744-757, Aug 2004.

[4] F. Z. Peng, “Z-source inverter, ” IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. 504-510, Mar 2003.

[5] F. Z. Peng, A. Joseph, J. Wang, M. Shen, L. Chen, Z. Pan, E. Ortiz-Rivera, and Y. Huang, “Z-source inverter for motor drives, ” IEEE Trans. Power Electron., vol. 20, no. 4, pp. 857-863, July2005.

A DSP Based Digital Control Strategy for ZVS Bidirectional Buck+Boost Converter

ABSTRACT:

 The non-isolated bidirectional DC-DC converters are the most popular topology for low or medium power of the hybrid electric vehicle (HEV) or fuel cell vehicle (FCV) applications. These kinds of converters have the advantages of simple circuit topology, bidirectional flows, zero-voltageswitching (ZVS), high efficiency, and high power density. The turned-on ZVS for all MOSFETs is achieved by the negative offset of the inductor current at the beginning and the end of each switching period. To do this, the converter requires a complex switching strategy which is preferred to be implemented by the digital signal processing (DSP). This paper presents the digital implementation of the switching pattern to ensure the ZVS condition for such converter. A 5kW prototype is performed to verify the capability of such control scheme.

KEYWORDS:

  1. DC-DC converter
  2. Bidirectional converter
  3. Digital control
  4. Phase shift control

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig1. Bidirectional dc dc converter

EXPECTED SIMULATION RESULTS:

 Fig. 2. Inductor current waveforms of (a) boost mode and (b) buck mode

 

Fig. 3. ZVS turn on of switch S1

Fig. 4. Overall efficiency of both boost and buck operating modes

 CONCLUSION:

 A DSP based digital control strategy for the bidirectional DC-DC converter is proposed in this paper. The new control strategy provides a negative inductor current at the beginning of each pulse period that, in conjunction with just the parasitic MOSFET output capacitances but no additional components, allows ZVS with the full voltage and load range. The DSP chip TMS320F28035 from Texas Instruments is employed to perform this control algorithm. The experimental results not only show the ZVS for four switches but also provide an excellent overall efficiency at least 96% at the power range.

REFERENCES:

 [1] S. S. Williamson, S. M. Lukic, and A. Emadi, “Comprehensive drive train efficiency analysis of hybrid electric and fuel cell vehicles based on motor controller efficiency modeling,” IEEE Trans. Power Electron., vol. 21, no. 3, pp. 730-740, May 2006.

[2] K. Wang, C. Y. Lin, L. Zhu, D. Qu, F. C. Lee, and J. Lai, “Bidirectional dc to dc converters for fuel cell systems,” in Conf. Rec. 1998 IEEE Workshop Power Electronics in Transportation, pp. 47-51.

[3] A. Emadi, S. S. Williamson, and A. Khaligh, “Power electronics intensive solutions for advanced electric, hybrid electric, and fuel cell vehicular power systems,” IEEE Trans. Power Electron., vol. 21, no. 3, pp. 567-577, May 2006.

[4] D. Patel Ankita, “Analysis of bidirectional Buck-Boost converter by using PWM control scheme,” ISSN: 2321-9939, Electronics and Communication, Marwadi Education Foundation Group of Institute, Rajkot, India.

[5] Texas Instruments, “Modeling of bidirectional Buck/Boost converter for digital control using C2000 microcontroller,” Application report SPRABX5, January 2015.

Grid to Vehicle and Vehicle to Grid Energy Transfer using Single-Phase Bidirectional ACDC Converter and Bidirectional DC – DC converter

ABSTRACT:

 In this paper, a configuration of a single-phase bidirectional AC-DC converter and bidirectional DC-DC converter is proposed to transfer electrical power from the grid to an electrical vehicle (EV) and from an EV to the grid while keeping improved power factor of the grid. In first stage, a 230 V 50 Hz AC supply is converted in to 380V dc using a single-phase bidirectional AC-DC converter and in the second stage, a bidirectional buck–boost dc-dc converter is used to charge and discharge the battery of the PHEV (Plug-in Hybrid Electric Vehicle). In discharging mode, it delivers energy back to the grid at 230V, 50 Hz. A battery with the charging power of 1.2 kW at 120V is used in PHEV. The buck-boost DC-DC converter is used in buck mode to charge and in a boost mode to discharge the battery. A proportional-integral (PI) controller is used to control the charging current and voltage. Simulated results validate the effectiveness of proposed algorithm and the feasibility of system.

KEYWORDS:

  1. Plug-in Hybrid Electric Vehicle (PHEV)
  2. Bidirectional AC-DC Converter
  3. DC-DC Converter
  4. Vehicle to grid (V2G)
  5. Electric drive vehicle (EDVs)

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 Fig.1 Proposed configuration for V2G and G2V Energy transfer

 EXPECTED SIMULATION RESULTS:

 Fig.2 Charging and discharging of PHEV battery (Full profile)

               Fig.3 Charging and discharging of PHEV battery (in large view)

Fig.4. Discharging and Charging of PHEV battery demonstrating unity

Power factor operation

Fig.5 Waveform and harmonics spectrum of the discharging grid current

Fig.6 Waveform and harmonics spectrum of the Charging grid current

CONCLUSION:

The proposed converter has delivered the AC current to/and from the grid at unity power factor and at very low current harmonics which ultimately prolongs the life of the converter and the battery and minimizes the possibility of distorting the grid voltage. It also enables V2G interactions which could be utilized to improve the efficiency of the grid.

REFERENCES:

[1] Young-Joo Lee, Alireza Khaligh, and Ali Emadi, “Advanced Integrated Bidirectional AC/DC and DC/DC Converter for Plug-In Hybrid Electric Vehicles,” IEEE Trans. on Vehicular Tech. vol. 58, no. 8, pp. 3970-3980, Oct, 2009.

[2] Bhim Singh, Brij N. Singh, Ambrish Chandra, Kamal Al-Haddad, Ashish Pandey and Dwarka P. Kothari, “A review of single-phase improved power quality ac–dc converters,” IEEE Trans. Industrial Electronics, vol. 50, no. 5, pp. 962-981, Oct. 2003.

[3] M.C. Kisacikoglu, B. Ozpineci and L.M. Tolbert, “Examination of a PHEV bidirectional charger system for V2G reactive power compensation,” in Proc. of Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2010, 21-25 Feb.2010, pp.458-465.

[4] M.C. Kisacikoglu, B. Ozpineci and L.M. Tolbert, “Effects of V2G reactive power compensation on the component selection in an EV or PHEV bidirectional charger,” in Proc. of Energy Conversion Congress and Exposition (ECCE), 2010 IEEE, 12-16 Sept. 2010, pp.870-876.

[5] W. Kempton and J. Tomic, “Vehicle-to-grid power fundamentals: Calculating capacity and net revenue,” J. Power Sources, vol. 144, no. 1, pp. 268–279, Jun. 2005.

Power management in PV-battery-hydro based standalone microgrid

ABSTRACT:

This work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC–DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG. The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. The battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. The experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:
Fig. 1 Microgrid Topology and MPPT Control

(a) Proposed PV-battery-hydro MG

 EXPECTED SIMULATION RESULTS

 

 Fig. 2 Dynamic performance of PV-battery-hydro based MG following by solar irradiance change

(a) vsab, isc, iLc and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isa, iLa and ivsca, (d) Vdc, Ipv, Vb and Ib

 

Fig. 3 Dynamic performance of hydro-battery-PV based MG under load perturbation

(a) vsab, isc, Ipv and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isc, Ipv and ivscc, (d) Vdc, Ipv, and Vb

CONCLUSION:

In the proposed MG, an integration of hydro with the battery, compensates the intermittent nature of PV array. The proposed system uses the hydro, solar PV and battery energy to feed the voltage (Vdc), solar array current (Ipv), battery voltage (Vb) and battery current (Ib). When the load is increased, the load demand exceeds the hydro generated power, since SEIG operates in constant power mode condition. This system has the capability to adjust the dynamical power sharing among the different RES depending on the availability of renewable energy and load  demand. A bidirectional converter controller has been successful to maintain DC-link voltage and the battery charging and discharging currents. Experimental results have validated the design and  control of the proposed system and the feasibility of it for rural area electrification.

REFERENCES:

[1] Ellabban, O., Abu-Rub, H., Blaabjerg, F.: ‘Renewable energy resources: current status, future prospects and technology’, Renew. Sustain. Energy Rev.,2014, 39, pp. 748–764

[2] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89  (8), pp. 1216–1226

[3] Malik, S.M., Ai, X., Sun, Y., et al.: ‘Voltage and frequency control strategies of hybrid AC/DC microgrid: a review’, IET Renew. Power Gener., 2017, 11, (2), pp. 303–313

[4] Kusakana, K.: ‘Optimal scheduled power flow for distributed photovoltaic/ wind/diesel generators with battery storage system’, IET Renew. Power  Gener., 2015, 9, (8), pp. 916–924

[5] Askarzadeh, A.: ‘Solution for sizing a PV/diesel HPGS for isolated sites’, IET Renew. Power Gener., 2017, 11, (1), pp. 143–151

 

 

 

Single- and Two-Stage Inverter-Based Grid Connected Photovoltaic Power Plants With Ride-Through Capability Under Grid Faults

IEEE TRANSACTIONS ON SUSTAINABLE ENERGY, VOL. 6, NO. 3, JULY 2015

 ABSTRACT Grid-connected distributed generation sources interfaced with voltage source inverters (VSIs) need to be disconnected from the grid under: 1) excessive dc-link voltage; 2) excessive ac currents; and 3) loss of grid-voltage synchronization. In this paper, the control of single and two stage grid-connected VSIs in photovoltaic (PV) power plants is developed to address the issue of inverter disconnecting under various grid faults. Inverter control incorporates reactive power support in the case of voltage sags based on the grid codes’ (GCs) requirements to ride-through the faults and support the grid voltages. A case study of a 1-MW system simulated in MATLAB/Simulink software is used to illustrate the proposed control. Problems that may occur during grid faults along with associated remedies are discussed. The results presented illustrate the capability of the system to ride-through different types of grid faults.

 

KEYWORDS:

  1. DC–DC converter
  2. Fault-ride-through
  3. Photovoltaic (PV) systems
  4. Power system faults
  5. Reactive power support
  6. single and two stage inverter

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

single and two stage inverter

Fig. 1. Diagram of a single-stage GCPPP

 single and two stage inverter

Fig. 2. Diagram of the two-stage conversion-based GCPPP

 

EXPECTED SIMULATION RESULTS:

Fig. 3. Short-circuiting the PV panels: (a) grid voltages; (b) grid currents; and (c) dc-link voltage when applying a 60% SLG voltage sag at MV side of the transformer.

Fig. 4. Short-circuiting the PV panels: (a) overall generated power; (b) injected active power; and (c) reactive power to the grid.

Fig. 5. Turning the dc–dc converter switch ON: (a) grid voltages; (b) grid currents; and (c) dc-link voltage when applying a 60% SLG voltage sag at the MV side.

Fig. 6. Control of the dc–dc converter to produce less power under voltage sag: (a) grid voltages; (b) grid currents; (c) dc-link voltage; (d) input voltage of the dc–dc converter; (e) estimated duty cycle; and (f) actual duty cycle under a 3LG with 45% voltage sag at MV side.

Fig. 7. Control of the dc–dc converter to produce less power under voltage sag: (a) grid voltages under a 3LG with 45% voltage sag at MV side; (b) related grid currents for G = 300 W/m2; and (c) related dc-link voltage; (d) grid voltages under an SLG with 65% voltage sag at theMV side; (e) related grid currents for G = 1000 W/m2; (f) related dc-link voltage; (g) related grid currents under G = 300 W/m2; and (h) related dc-link voltage.”

single and two stage inverter

CONCLUSION

Performance requirements of GCPPPs under fault conditions for single and two stage grid-connected inverters have been addressed in this paper. Some modifications have been proposed for controllers to make the GCPPP ride-through compatible to any type of faults according to the GCs. These modifications include applying current limiters and controlling the dc-link voltage by different methods. It is concluded that for the single-stage configuration, the dc-link voltage is naturally limited and therefore, the GCPPP is self-protected, whereas in the two-stage configuration it is not. Three methods have been proposed for the two-stage configuration to make the GCPPP able to withstand any type of faults according to the GCs without being disconnected. The first two methods are based on not generating any power from the PV arrays during the voltage sags, whereas the third method changes the power point of the PV arrays to inject less power into the grid compared with the prefault condition. The validity of all the proposed methods to ride-through voltage sags has been demonstrated by multiple case studies performed by simulations.

 

REFERENCES

  1. Trilla et al., “Modeling and validation of DFIG 3-MW wind turbine using field test data of balanced and unbalanced voltage sags,” IEEE Trans. Sustain. Energy, vol. 2, no. 4, pp. 509–519, Oct. 2011.
  2. Popat, B. Wu, and N. Zargari, “Fault ride-through capability of cascaded current-source converter-based offshore wind farm,” IEEE Trans. Sustain. Energy, vol. 4, no. 2, pp. 314–323, Apr. 2013.
  3. Marinopoulos et al., “Grid integration aspects of large solar PV installations: LVRT capability and reactive power/voltage support requirements,” in Proc. IEEE Trondheim Power Tech, Jun. 2011, pp. 1–8.
  4. Islam, A. Al-Durra, S. M. Muyeen, and J. Tamura, “Low voltage ride through capability enhancement of grid connected large scale photovoltaic system,” in Proc. 37th Annu. Conf. IEEE Ind. Electron. Soc. (IECON), Nov. 2011, pp. 884–889.

 MPPT with Single DC–DC Converter and Inverter for Grid-Connected Hybrid Wind-Driven PMSG–PV System

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, 2015

ABSTRACT: A new topology of a hybrid distributed generator based on photovoltaic and wind-driven permanent magnet synchronous generator is proposed. In this generator, the sources are connected together to the grid with the help of only a single boost converter followed by an inverter. Thus, compared to earlier schemes, the proposed scheme has fewer power converters. A model of the proposed scheme in the d − q-axis reference frame is developed. Two low-cost controllers are also proposed for the new hybrid scheme to separately trigger the dc–dc converter and the inverter for tracking the maximum power from both sources. The integrated operations of both proposed controllers for different conditions are demonstrated through simulation and experimentation. The steady-state performance of the system and the transient response of the controllers are also presented to demonstrate the successful operation of the new hybrid system. Comparisons of experimental and simulation results are given to validate the simulation model.

KEYWORDS:

  1. Grid-connected hybrid system
  2. Hybrid distributed generators (DGs)
  3. Smart grid
  4. Wind-driven PMSG–PV

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Proposed DG system based on PMSG–PV sources.

EXPECTED SIMULATION RESULTS:

(a)

(b)

Fig. 2. DC link steady-state waveforms. (a) Experimental (voltage—50 V/div, current—10 A/div, and time—500 ms/div). (b) Simulated (voltage—20 V/div, current—5 A/div, and time—500 ms/div.

(a)

(b)

Fig. 3. Steady-state grid voltage and current waveforms. (a) Experimental (voltage—50 V/div, current—10 A/div, and time—20 ms/div). (b) Simulated (voltage—50 V/div, current—5 A/div, and time— 20 ms/div).

Experimental (Voltage 50V/div, Duty-cycle 0.6/div, Time 2s/div)

Simulated (Voltage 20V/div, Duty-cycle 0.5/div, Time 2s/div)

(a) Changes in rectifier output voltage and duty cycle of the boost converter.

Experimental (Voltage 50V/div, Current 10 A/div, Time 2s/div)

Simulated (Voltage 50V/div, Current 10/div)

(b) Changes in dc-link voltage and current

Experimental (Voltage 50V/div, Current 10A/div, Time 2s/div)

Simulated (Voltage 50V/div, Current 10A/div, Time 2s/div)

Fig.4. Transient response for a step change in PMSG shaft speed.. (c) Changes in grid current.

 CONCLUSION:

A new reliable hybrid DG system based on PV and wind driven PMSG as sources, with only a boost converter followed by an inverter stage, has been successfully implemented. The mathematical model developed for the proposed DG scheme has been used to study the system performance in MATLAB. The investigations carried out in a laboratory prototype for different irradiations and PMSG shaft speeds amply confirm the utility of the proposed hybrid generator in zero-net-energy buildings. In addition, it has been established through experimentation and simulation that the two controllers, digital MPPT controller and hysteresis current controller, which are designed specifically for the proposed system, have exactly tracked the maximum powers from both sources. Maintenance-free operation, reliability, and low cost are the features required for the DG employed in secondary distribution systems. It is for this reason that the developed controllers employ very low cost microcontrollers and analog circuitry. Furthermore, the results of the experimental investigations are found to be matching closely with the simulation results, thereby validating the developed model. The steady state waveforms captured at the grid side show that the power generated by the DG system is fed to the grid at unity power factor. The voltage THD and the current THD of the generator meet the required power quality norms recommended by IEEE. The proposed scheme easily finds application for erection at domestic consumer sites in a smart grid scenario.

REFERENCES:

[1] J. Byun, S. Park, B. Kang, I. Hong, and S. Park, “Design and implementation of an intelligent energy saving system based on standby power reduction for a future zero-energy home environment,” IEEE Trans. Consum. Electron., vol. 59, no. 3, pp. 507–514, Oct. 2013.

[2] J. He, Y. W. Li, and F. Blaabjerg, “Flexible microgrid power quality enhancement using adaptive hybrid voltage and current controller,” IEEE Trans. Ind. Electron., vol. 61, no. 6, pp. 2784–2794, Jun. 2014.

[3] W. Li, X. Ruan, C. Bao, D. Pan, and X. Wang, “Grid synchronization systems of three-phase grid-connected power converters: A complexvector- filter perspective,” IEEE Trans. Ind. Electron., vol. 61, no. 4, pp. 1855–1870, Apr. 2014.

[4] C. Liu, K. T. Chau, and X. Zhang, “An efficient wind-photovoltaic hybrid generation system using doubly excited permanent-magnet brushless machine,” IEEE Trans. Ind. Electron, vol. 57, no. 3, pp. 831–839, Mar. 2010.

[5] S. A. Daniel and N. A. Gounden, “A novel hybrid isolated generating system based on PV fed inverter-assisted wind-driven induction generators,” IEEE Trans. Energy Convers., vol. 19, no. 2, pp. 416–422, Jun. 2004.

Design of Fuzzy Logic Based Maximum Power Point Tracking Controller for Solar Array for Cloudy Weather Conditions

 

ABSTRACT:

This paper proposes Maximum Power Point Tracking (MPPT) of a photovoltaic system under variable temperature and solar radiation conditions using Fuzzy Logic Algorithm. The cost of electricity from the PV array is more expensive than the electricity from the other non-renewable sources. So, it is necessary to operate the PV system at maximum efficiency by tracking its maximum power point at any weather conditions 111. Boost converter increases output voltage of the solar panel and converter output voltage depends upon the duty cycle of the MOSFET present in the boost converter. The change in the duty cycle is done by Fuzzy logic controller by sensing the power output of the solar panel. The proposed controller is aimed at adjusting the duty cycle of the DC-DC converter switch to track the maximum power of a solar cell array. MATLABI Simulink is used to develop and design the PV array system equipped with the proposed MPPT controller using fuzzy logic 12][31. The results show that the proposed controller is able to track the MPP in a shorter time with less fluctuation. The complete hardware setup with fuzzy logic controller is implemented and the results are observed and compared with the system without MPPT (Fuzzy logic controller).

KEYWORDS:

  1. MPPT
  2. Fuzzy Logic Control
  3. DC-DC Converter,
  4. Photo voltaic systems.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of MPPT of PV array.

EXPECTED SIMULATION RESULTS:

 Fig. 2. Power Vs output voltage

Fig. 3. Voltage Vs Current output of solar panel

Fig. 4. Output voltage of the solar panel without MPPT.

Fig. 5. Output of the solar panel with MPPT FLC under cloudy weather conditions.

Fig. 6. PWM output when driven by FLC

 CONCLUSION:

This paper presents an intelligent control method of tracking maximum power and Simulation and hardware result show that proposed MPPT controller increases the efficiency of the PV array energy conversion efficiency. Results are compared with the panel without MPPT controller.

REFERENCES:

[1] Chetan Singh Solanki,” Solar Photo Voltaics “, PHI Learning pvt. Ltd ,2009.

[2] Bor-Ren Lin,”Analysis of Fuzzy Control Method Applied to DCDC Converter controf’ , IEEE Prowe .h g APK’93, pp. 22- 28,1993.

[3] Rohin M.Hillooda, Adel M.Shard,”A rule Based Fuzzy Logic controller for a PWM inverter in Photo Voltaic Energy Conversion Scheme”, IAS’SZ, PP.762-769, 1993.

[4] Pongsakor Takum, Somyot Kaitwanidvilai and Chaiyan Jettasen ; ‘Maximum POlVer Point Tracking using jilzzy logic control for photovoltaic systems.’ Proceedings Of International Multiconference of Engineers and Computer scientists ,Vol 2,March 2011.

[5] M.S.Cheik , Larbes, G.F Kebir and A ZerguelTas; ‘Maximum power point tracking using a jilzzy logic control scheme.’; ‘Departementd’Electronique’, Revue des Energies Renouvelables, VoI.lO,No 32 , September 2007, pp 387-395

Analysis and design of a current-fed zero-voltage-switching and zero-current-switching CL-resonant push–pull dc–dc converter

 

ABSTRACT:

A current-fed zero-voltage-switching (ZVS) and zero-current-switching (ZCS) CL-resonant push–pull dc – dc converter is presented in this paper. The proposed push–pull converter topology is suitable for unregulated low-voltage to high-voltage power conversion with low ripple input current. The resonant frequency of both capacitor and inductor is operated at approximately twice the main switching frequency. In this topology, the main switch is operated under ZVS because of the commutation of the transformer magnetising current and the parasitic drain–source capacitance. Because of the leakage inductance of the transformer and the resonant capacitance from the resonant circuit, both the main switch and output rectifier are operated by implementing ZCS. The operation and performance of the proposed converter has been verified on a 400-W prototype.

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Figure 1 Schematic diagram of the proposed current-fed ZVS–ZCS CL-resonant push–pull dc–dc converter

EXPECTED SIMULATION RESULTS:

Figure 2 Measured waveforms of gate to source voltage and drain to source voltage a ZVS operations for Q1 and Q2 at the full load b Expanded scale of Fig. 7a in point A

 

Figure 3 ZCS operations for Q1 and Q2 at the full load

Figure 4 ZCS operations for rectifier diode at the full load

Figure 5 Waveforms of vin, iin, ip and icr at the full load

Figure 6 Waveforms with excessive dead time

Figure 7 Step change with resistance load

a Load connection

b Load disconnection

CONCLUSION:

This study proposed, analysed, and quantified a current-fed ZVS–ZCS CL-resonant push–pull dc–dc converter that utilises the commutation of the transformer magnetizing current and the parasitic drain–source capacitance to obtain the main switch to be operated under ZVS. By using the leakage inductance of a transformer and resonant capacitor, a sinusoidal current is formed in this resonant circuit by turning on and off the switch. Thus, both the main switch and the output rectifier can be operated under ZCS. Because this proposed converter includes an input inductance, the input terminal of the converter cannot be added with a filter. This converter can reach a steady state with a small ripple input current, which is especially suitable for unregulated dc–dc conversion from a low-voltage high-current source. From the experimental results, the main switch can be operated using both ZVS and ZCS and the output rectifier can be operated using ZCS. The operating principles and theoretical analysis of this proposed converter were verified by using a 400-W and 65-kHz prototype. The overall efficiency of the converter nearly reached 93% at full output power.

REFERENCES:

[1] SHOYAMA M., HARADA K.: ‘Steady-state characteristics of the push-pull dc-to-dc converter’, IEEE Trans. Aerosp. Electron. Syst., 1984, 20, (1), pp. 50–56

[2] THOTTUVELIL V.J., WILSON T.G., QWEN H.A.: ‘Analysis and design of a push-pull current-fed converter’. Proc. IEEE PESC, 1981, vol. 5, pp. 192–203

[3] REDL R., SOKAL N.: ‘Push –pull current-fed, multiple output regulated wide input range dc/dc power converter with only one inductor and with 0 to 100% switch duty ratio: operation at duty ratio below 50%’. Proc. IEEE PESC, 1981, pp. 204–212

[4] WILDON C.P., DE ARAGAO F., BARBI I.: ‘A comparison between two current-fed push-pull dc-dc converters – analysis, design and experimentation’. Proc. IEEE INTELEC, 1996, pp. 313–320

[5] YING J., ZHU Q., LIN H., WU Z.: ‘A zero-voltage-switching (ZVS) push-pull dc/dc converter for UPS’. Proc. IEEE PEDS, 2003, pp. 1495–1499

Naturally Clamped Zero Current Commutated Soft-switching Current-fed Push-Pull DC/DC Converter: Analysis, Design, and Experimental Results  

 

ABSTRACT:

The proposed converter has the following features: 1) zero current commutation (ZCC) and natural voltage clamping (NVC) eliminate the need for active-clamp circuits or passive snubbers required to absorb surge voltage in conventional current-fed topologies; 2) Switching losses are reduced significantly owing to zero-current switching (ZCS) of primary side devices and zero-voltage switching (ZVS) of secondary side devices. Turn-on switching transition loss of primary devices is also negligible. 3) Soft-switching and NVC are inherent and load independent. 4) The voltage across primary side device is independent of duty cycle with varying input voltage and output power and clamped at rather low reflected output voltage enabling the use of low voltage semiconductor devices. These merits make the converter good candidate for interfacing low voltage dc bus with high voltage dc bus for higher current applications. Steady state, analysis, design, simulation and experimental results are presented.

KEYWORDS:

  1. Current-fed converter
  2. DC/DC converter
  3. Natural clamping
  4. Soft-switching
  5. Zero-current commutation

 

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Diagram of a FCV propulsion system.

CIRCUIT DIAGRAM:

Fig.2. Proposed ZCS current-fed push-pull dc/dc converter.

 

EXPECTED SIMULATION RESULTS:

Fig. 3. Operating waveforms of proposed ZCS current-fed push-pull converter in the buck mode.

Fig. 4. Simulation results for output power of 250W at 300V. (a) Current through input inductor iL and voltage VAB. (b) Primary switches currents iS1 and iS2 and secondary switches currents iS3 and iS4.

Fig. 5. Experimental results for output power of 250W at 300V(x-axis: 2μs/div): (a) Boost inductor current iL (5A/div), (b) Voltage vAB (100V/div) and voltage across secondary of transformer vsec (500 V/div), (c-d) Gate-to-source voltage Vgs (10V/div) and drain-to-source voltage Vds (50V/div) across the primary side MOSFETs and currents through them (10A/div). (e-f) Gate-to-source voltage Vgs (10V/div) and drain-to-source voltage Vds (200V/div) across the secondary side MOSFETs and currents through them (2A/div).

Fig. 6. Experimental results for output power of 100W at 300V(x-axis: 2μs/div): (a) Boost inductor current iL (5A/div), (b) Voltage vAB (100V/div) and voltage across secondary of transformer vsec (500 V/div), (c-d) Gate-to-source voltage Vgs (10V/div) and drain-to-source voltage Vds (50V/div) across the primary side MOSFETs and currents through them (10A/div). (e-f) Gate-to-source voltage Vgs (10V/div) and drain-to-source voltage Vds (200V/div) across the secondary side MOSFETs and currents through them (2A/div).

 

CONCLUSION:

This paper presents a novel soft-switching snubberless bidirectional current-fed isolated push-pull dc/dc converter for application of the ESS in FCVs. A novel secondary side modulation method is proposed to eliminate the problem of voltage spike across the semiconductor devices at turn-off. The above claimed ZCC and NVC of primary devices without any snubber are demonstrated and confirmed by the simulation and experimental results. ZCS of primary side devices and ZVS of secondary side devices are achieved, which reduces the switching losses significantly. Soft-switching is inherent and is maintained independent of load. Once ZCC, NVC, and soft-switching are designed to be obtained at rated power, it is guaranteed to happen at reduced load unlike voltage-fed converters. Turn-on switching transition loss of primary devices is also shown to be negligible. Hence maintaining soft-switching of all devices substantially reduces the switching loss and allows higher switching frequency operation for the converter to achieve a more compact and higher power density system. Proposed secondary modulation achieves natural commutation of primary devices and clamps the voltage across them at low voltage (reflected output voltage) independent of duty cycle. It therefore eliminates requirement of active-clamp or passive snubber. Usage of low voltage devices results in low conduction losses in primary devices, which is significant due to higher currents on primary side. The proposed modulation method is simple and easy to implement. These merits make the converter promising for interfacing low voltage dc bus with high voltage dc bus for higher current applications such as FCVs, front-end dc/dc power conversion for renewable (fuel cells/PV) inverters, UPS, microgrid, V2G, and energy storage. The specifications are taken for FCV but the proposed modulation, design, and the demonstrated results are suitable for any general application of current-fed converter (high step-up). Similar merits and performance will be achieved.

REFERENCES:

[1] A. Khaligh and Z. Li, “Battery, ultracapacitor, fuel cell, and hybrid energy storage systems for electric, hybrid electric, fuel cell, and plug-in hybrid electric vehicles: State of the art”, IEEE Trans. on Vehicular Technology, vol. 59, no. 6, pp. 2806- 2814, Oct. 2009.

[2] A. Emadi, and S. S. Williamson, “Fuel cell vehicles: opportunities and challenges,” in Proc. IEEE PES, 2004, pp. 1640-1645.

[3] K. Rajashekhara, “Power conversion and control strategies for fuel cell vehicles,” in Proc. IEEE IECON, 2003, pp. 2865-2870.

[4] A. Emadi, S. S. Williamson, and A. Khaligh, “Power electronics intensive solutions for advanced electric, hybrid electric, and fuel cell vehicular power systems,” IEEE Trans. Power Electron., vol. 21, no. 3, pp. 567–577, May. 2006.

[5] A. Emadi, K. Rajashekara, S. S. Williamson, and S. M. Lukic, “Topological overview of hybrid electric and fuel cell vehicular power system architectures and configurations” IEEE Trans. on Vehicular

Technology, vol. 54, no. 3, pp. 763–770, May. 2005.