Current Control of Three-phase Grid connected PV Inverters using Adaptive PR Controller

ABSTRACT:

In recent years, there has been a rapid increase in the number of grid connected three phase inverter systems being connected to the distribution network. As a result, the need for high quality, low harmonic distortion, and current injection into the grid is essential. To achieve this, careful consideration of the inverter controller is necessary. Many control methods are based on the traditional proportional-integral controller (PI), or the more recently adopted Proportional Resonant controller (PR). This paper presents a new technique of minimizing the error of the current control in a three phase grid connected inverter using a readily implementable Adaptive Proportional Resonance controller. Simulation and experimental results demonstrate the effectiveness of the proposed technique.

 

KEYWORDS:

  1. Proportional Resonant
  2. Grid- connected Inverter
  3. LCL filter.

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

 Adaptive PR controller in stationary reference control

Fig 1 Adaptive PR controller in stationary reference control

  

EXPECTED SIMULATION RESULTS:

 Simulation result waveforms. (a) Three phase voltage waveform. (b) Three phase current waveform. 

Fig.2 Simulation result waveforms. (a) Three phase voltage waveform. (b) Three phase current waveform.

Simulation waveforms for conventional PR controller. (a) i-alpha. (b) ibeta.

Fig.3 Simulation waveforms for conventional PR controller. (a) i-alpha. (b) ibeta.

. Simulation waveforms for adaptive PR controller. (a) i-alpha. (b) i-beta.

Fig. 4. Simulation waveforms for adaptive PR controller. (a) i-alpha. (b) i-beta.

 Simulation result waveforms unbalanced grid condition. (a) Three phase voltage waveform. (b) Three phase current waveform.

Fig. 5. Simulation result waveforms unbalanced grid condition. (a) Three phase voltage waveform. (b) Three phase current waveform.

   

CONCLUSION:

This paper has considered the impact of an adaptive PR current control scheme of a three phase grid connected inverter. In particular, this work has shown the performance of the adaptive PR controller compared with the conventional PR controller which is popular in grid connected inverters. Simulation studies confirm that the adaptive PR controller demonstrates better performance under normal and abnormal operating conditions. There is no steady state error output, and the harmonic content of the current waveform is very low. In addition, the adaptive PR controller offers superior output power regulation, and improved power quality performance. Overall, it can be concluded that the adaptive PR controller is better suited in the event of grid faults, or operation in weak grid environments, compared to fix gain controllers.

 

REFERENCES:

  • Wuhua and H. Xiangning, “Review of Nonisolated High-Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications,” Industrial Electronics, IEEE Transactions on, vol. 58, pp. 1239-1250, 2011.
  • Chenlei, R. Xinbo, W. Xuehua, L. Weiwei, P. Donghua, and W. Kailei, “Step-by-Step Controller Design for LCL-Type Grid- Connected Inverter with Capacitor–Current-Feedback Active-Damping,” Power Electronics, IEEE Transactions on, vol.29, pp. 1239-1253, 2014.
  • “IEEE Standard for Interconnecting Distributed Resources With Electric Power Systems,” IEEE Std 1547-2003, 0_1-16, 2003.
  • Nicastri and A. Nagliero, “Comparison and evaluation of the PLL techniques for the design of the grid-connected inverter systems,” in Industrial Electronics (ISIE), 2010 IEEE International Symposium on, 2010, pp. 3865-3870.

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Control and Performance Analysis of a Single-Stage Utility-Scale Grid-Connected PV System

IEEE SYSTEMS JOURNAL, VOL. 11, NO. 3, SEPTEMBER 2017

ABSTRACT:

For utility-scale photovoltaic (PV) systems, the control objectives, such as maximum power point tracking, synchronization with grid, current control, and harmonic reduction in output current, are realized in single stage for high efficiency and simple power converter topology. This paper considers a highpower three-phase single-stage PV system, which is connected to a distribution network, with a modified control strategy, which includes compensation for grid voltage dip and reactive power injection capability. To regulate the dc-link voltage, a modified voltage controller using feedback linearization scheme with feedforward PV current signal is presented. The real and reactive powers are controlled by using dq components of the grid current. A small-signal stability/eigenvalue analysis of a grid-connected PV system with the complete linearized model is performed to assess the robustness of the controller and the decoupling character of the grid-connected PV system. The dynamic performance is evaluated on a real-time digital simulator.

 

KEYWORDS:

  1. DC-link voltage control
  2. Feedback linearization (FBL)
  3. Photovoltaic (PV) systems
  4. Reactive power control
  5. Small signal stability analysis
  6. Voltage dip.

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

One of the four 375-kW subsystems.

Fig. 1. One of the four 375-kW subsystems.

  

EXPECTED SIMULATION RESULTS:

(a) PV array voltage for MPPT. (b) PV array (PPV) and grid injected real power (Pg). (c) Grid injected reactive power (Qg).

Fig. 2. (a) PV array voltage for MPPT. (b) PV array (PPV) and grid injected real power (Pg). (c) Grid injected reactive power (Qg).

Grid injected currents and THD.

Fig. 3. Grid injected currents and THD.

PV system response to voltage dip in grid.

Fig. 4 PV system response to voltage dip in grid.

PV system response to a three-phase fault at bus 3.

Fig. 5. PV system response to a three-phase fault at bus 3.

PV system response to an LG fault.

Fig. 6. PV system response to an LG fault.

Pg  response of the whole 1.5-MW PV system.

Fig. 7. Pg  response of the whole 1.5-MW PV system.

 

CONCLUSION:

The proposed modified dc-link voltage controller with FBL technique, using INC MPPT, and real and reactive power controls with enhanced filter for compensation for grid voltage dips has been tested at different insolation levels on a real-time digital simulator (RTDS). Small-signal analysis of a PV system connected to an IEEE 33-bus distributed system is performed. The results from simulation and eigenvalue analysis demonstrate the effectiveness of the FBL controller compared with the controller without FBL. It is found that the FBL controller  outperforms the controllerwithout FBL, as the FBL controller’s  performance is linear at different operating conditions. With grid voltage dip compensator filter, the dynamic performance is much improved in terms of less oscillations and distortion in waveforms. In addition, the eigenvalue analysis shows that the effect of the disturbance in distribution system is negligible on PV system stability as the eigenmodes of the PV system are almost independent of the distribution system. This has been also confirmed by three-phase fault analysis of distribution system in RTDS model. The controller performance is also validated on 4×375 kW PV units connected to the distribution system.

 

REFERENCES:

  • Oprisan and S. Pneumaticos, “Potential for electricity generation from emerging renewable sources in Canada,” in Proc. IEEE EIC Climate Change Technol. Conf., May 2006, pp. 1–10.
  • Petrone, G. Spagnuolo, R. Teodorescu, M. Veerachary, and M. Vitelli, “Reliability issues in photovoltaic power processing systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2569–2580, Jul. 2008.
  • Jain and V. Agarwal, “A single-stage grid connected inverter topology for solar PV systems with maximum power point tracking,” IEEE Trans. Power Electron., vol. 22, no. 5, pp. 1928–1940, Jul. 2007.
  • Katiraei and J. Aguero, “Solar PV integration challenges,” IEEE Power Energy Mag., vol. 9, no. 3, pp. 62–71, May-Jun. 2011.
  • H. Ko, S. Lee, H. Dehbonei, and C. Nayar, “Application of voltageand current-controlled voltage source inverters for distributed generation systems,” IEEE Trans. Energy Convers., vol. 21, no. 3, pp. 782–792, Sep. 2006.

Three-phase grid connected PV inverters using the proportional resonance controller

2016 IEEE

ABSTRACT

The development in grid connected three phase inverter has increased the importance of achieving low distortion and high quality current waveform. This paper describes a method of reducing current ripple in a three phase grid connected inverter utilizing Proportional Resonance (PR) controller. The effectiveness of the PR current controller is demonstrated by comparing its performance with that of the Proportional Integral (PI) controller. Simulation and experimental results show that Proportional Resonance (PR) controller achieves better reduction in total harmonic distortion (THD) in the current signal spectrum.

 

KEYWORDS

  1. Grid-connected inverter
  2. LCL filter
  3. PI controller
  4. PR controller.

 

SOFTWARE:MATLAB/SIMULINK

  

BLOCK DIAGRAM:

block diagram

Fig.1. PI controller in synchronous reference scheme.

Fig. 2 PR controller in stationary reference control

SIMULATION RESULTS

Fig.3. The phase grid voltage

Fig.4. The phase current waveform using PI controller

 

Fig.5 The phase current waveform using Proportional resonance  controller

Fig.6. The FFT of the phase current waveform using PI controller

Fig.7. The FFT of the phase current waveform using Proportional Resonance controller

 

CONCLUSION

This paper has considered the impact of the current control scheme of a three-phase grid-connected inverter under normal and abnormal grid conditions using PI and PR controllers. In particular, this work has compared the performance of the industrially accepted PI controller, and the emerging PR controller which is popular in grid connected renewable energy applications. In keeping with the claims of other literature, simulation studies have confirmed that the PR controller shows better performance under normal operating conditions. There is no steady state error output, and the harmonic content of the current waveform is very low. Moreover, in this paper, the effect of grid voltage dips on the performance of the grid connected inverter was considered. Whilst the PI controller demonstrates very good performance, the Proportional Resonance controller offers superior output power regulation, and improved power quality performance. Overall, it suggests that the PR controller is better suited in the event of grid faults, or operation in weak grid environments.

 

REFERENCES

  1. Wuhua and H. Xiangning, “Review of Nonisolated High-Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications,” IEEE Trans. Ind Electron., vol. 58, pp. 1239-1250, 2011.
  2. Atkinson, G. Pannell, C. Wenping, B. Zahawi, T. Abeyasekera, and M. Jovanovic, “A doubly-fed induction generator test facility for grid fault ride-through analysis,” Instrumentation & Measurement Magazine, IEEE, vol. 15, pp. 20-27, 2012.
  3. Cecati, A. Dell’Aquila, M. Liserre, and V. G. Monopoli, “Design of H-bridge multilevel active rectifier for traction systems,” Industry Applications, IEEE Transactions on, vol. 39, pp. 1541-1550, 2003.
  4. Hassaine, E. Olias, J. Quintero, and V. Salas, “Overview of power inverter topologies and control structures for grid connected photovoltaic systems,” Renewable and Sustainable Energy Reviews, vol. 30, pp. 796-807, 2014.
  5. Nicastri and A. Nagliero, “Comparison and evaluation of the PLL techniques for the design of the grid-connected inverter systems,” in Industrial Electronics (ISIE), 2010 IEEE International Symposium on, 2010, pp. 3865-3870.

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Automatic droop control for a low voltage DC Microgrid

ABSTRACT

A DC microgrid (DC-MG) provides an effective mean to integrate various sources, energy storage units and loads at a common dc-side. The droop-based, in the context of a decentralized control, has been widely used for the control of the DC-MG. However, the conventional droop control cannot achieve both accurate current sharing and desired voltage regulation. This study proposes a new adaptive control method for DC-MG applications which satisfies both accurate current sharing and acceptable voltage regulation depending on the loading condition. At light load conditions where the output currents of the DG units are well below the maximum limits, the accuracy of the current sharing process is not an issue. As the load increases, the output currents of the DG units increase and under heavy load conditions accurate current sharing is necessary. The proposed control method increases the equivalent droop gains as the load level increases and achieves accurate current sharing. This study evaluates the performance and stability of the proposed method based on a linearised model and verifies the results by digital time-domain simulation and hardware-based experiments.

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig. 1 Simplified DC-MG with two DG units

 

EXPECTED SIMULATION RESULTS:

 

Fig. 2 Output currents of the DG units obtained in Simulation Results

a Conventional droop control method with small droop gains

b Conventional droop control method with large droop gains

c Proposed method

 

 

Fig. 3 Output voltages of the DG units obtained in Simulation Results

a Conventional droop control method with small droop gains

b Conventional droop control method with large droop gains

c Proposed method

 

CONCLUSION

This paper presents a new control scheme for DC-MG without using any communication links. In the conventional droop control, small droop gains result in good voltage regulation but inaccurate current sharing, and large droop gains result in accurate current sharing but unacceptable voltage regulation. To overcome this drawback, a new control method is proposed in which the equivalent droop gains automatically change based on the loading condition. The simulation results show and the experimental results verify that by adaptively changing the droop gains according to the load size, both accurate current sharing and desirable voltage regulation are achieved.

REFERENCES

  • Guerrero, J., Loh, P.C., Lee, T.-L., et al.: ‘Advanced control architectures for intelligent microgrids; part ii: Power quality, energy storage, and ac/dc microgrids’, IEEE Trans. Ind Electron., 2013, 60, (4), pp. 1263–1270
  • Vandoorn, T., De Kooning, J., Meersman, B., et al.: ‘Automatic power-sharing modification of p/v droop controllers in low-voltage resistive microgrids’, IEEE Trans. Power Deliv., 2012, 27, (4), pp. 2318–2325
  • Khorsandi, A., Ashourloo, M., Mokhtari, H.: ‘An adaptive droop control method for low voltage dc microgrids’. 2014 Fifth Power Electronics, Drive Systems and Technologies Conf. (PEDSTC), 2014, pp. 84–89
  • Loh, P.C., Li, D., Chai, Y.K., et al.: ‘Hybrid ac-dc microgrids with energy storages and progressive energy flow tuning’, IEEE Trans. Power Electron., 2013, 28, (4), pp. 1533–1543
  • Loh, P., Li, D., Chai, Y.K., et al.: ‘Autonomous operation of hybrid microgrid with ac and dc subgrids’, IEEE Trans. Power Electron., 2013, 28, (5), pp. 2214–2223

New Perspectives on Droop Control in AC Microgrid

ABSTRACT

Virtual impedance, angle droop and frequency droop control play important roles in maintaining system stability, and load sharing among distributed generators (DGs) in microgrid. These approaches have been developed into three totally independent concepts, but a strong correlation exists. In this letter, their similarities and differences are revealed. Some new findings are established as follows: 1) the angle droop control is intrinsically a virtual inductance method; 2) virtual inductance method can also be regarded as a special frequency droop control with a power derivative feedback; 3) the combination of virtual inductance method and frequency droop control is equivalent to the proportional–derivative (PD) type frequency droop, which is introduced to enhance the power oscillation damping. These relationships provide new insights into the design of the control methods for DGs in microgrid.

 

KEYWORDS

  1. Microgrid
  2. Droop control
  3. Virtual Impedance

 

SOFTWARE: MATLAB/SIMULINK

  

BLOCK DIAGRAM:

block diagram

Fig. 1 Equivalent output voltage source considering virtual impedance.

 

EXPECTED SIMULATION RESULTS:

Fig. 2 Power response during load change in conventional frequency droop. (a) Active power, (b) reactive power.

Fig. 3 Power response during load change in frequency droop plus virtual reactance. (a) Active power, (b) reactive power.

Fig. 4 Power response during load change in modified frequency droop. (a) Active power, (b) reactive power.

 

CONCLUSION

This letter compares the similarities and differences among three different concepts, virtual impedance method, angle droop and frequency droop control. Although each of them has been well researched, new perspectives are bought to readers by relating all three together. Thus, the inherent relationships are established, and new insights into the controller design are provided. Finally, the modified droop control unifies these three independently developed droop control methods into a generalized theoretical framework. To the reader, this letter explores the possibilities of further enhancing the existing methods and inspiring the development of new methods.

 

REFERENCES

  • M. Guerrero, L. GarciadeVicuna, and J. Matas, “Output impedance design of parallel-connected UPS inverters with wireless load-sharing control,” IEEE Trans. Ind. Electron., vol.52, no.4, pp.1126-1135, Aug.2005.
  • He and Y. Li, “Analysis, design, and implementation of virtual impedance for power electronics interfaced distributed generation,” IEEE Trans. Ind. Appl., vol.47, no.6, pp. 2525-2538, Nov. 2011.
  • Mahmood, D. Michaelson, and J. Jiang, “Accurate reactive power sharing in an islanded microgrid using adaptive virtual impedances,” IEEE Trans. Power Electron., vol.30, no.3, pp. 1605-1617, Mar.2015.
  • Majumder, G. Ledwich, A. Ghosh, S. Chakrabarti, and F. Zare, “Droop control of converter-interfaced microsources in rural distributed generation, ” IEEE Trans. Power Del., vol. 25, no. 4, pp.2768-2778, Oct. 2010.
  • C, Chandorkar, D. M. Divan, and R. Adapa, “Control of parallel connected inverters in standalone ac supply systems,” IEEE Trans. Ind. Appl., vol.29, no.1 pp.136-143, Jan.1993.

 

Control Strategy of Three-Phase Battery Energy Storage Systems for Frequency Support in Microgrids and with Uninterrupted Supply of Local Loads

 

ABSTRACT

Frequency control in autonomous microgrids (MG) with high penetration of renewable energy sources represents a great concern to ensure the system stability. In this regard, this paper presents an enhanced control method for battery energy storage systems (BESS) to support the frequency of MG and with the ability of disconnecting from the MG to supplying in the island mode a local consumer. A frequency controller, combining a conventional droop control with an inertia emulation function, governs the BESS active power transfer during the primary frequency control level. The BESS may also provide voltage support in the point of common coupling with the MG. Moreover, the proposed BESS may compensate, partially or totally, the power absorbed by the local loads in order to improve the MG frequency response. When the MG power quality worsens below a certain level, in terms of voltage and frequency, the BESS detaches from the MG and continues to operate islanded.

The reconnection is accomplished following a smoothly resynchronization of the local voltage with the MG, without disturbing the local loads supply. Additionally, this paper also discusses about the aspects related to the BESS management and its integration within the proposed system. The simulation and experimental results assess the feasibility of the proposed control solutions. Frequency control in autonomous microgrids (MG) with high penetration of renewable energy sources represents a great concern to ensure the system stability. In this regard, this paper presents an enhanced control method for battery energy storage systems (BESS) to support the frequency of MG and with the ability of disconnecting from the MG to supplying in the island mode a local consumer. A frequency controller, combining a conventional droop control with an inertia emulation function, governs the BESS active power transfer during the primary frequency control level. The BESS may also provide voltage support in the point of common coupling with the MG.

Moreover, the proposed BESS may compensate, partially or totally, the power absorbed by the local loads in order to improve the MG frequency response. When the MG power quality worsens below a certain level, in terms of voltage and frequency, the BESS detaches from the MG and continues to operate islanded. The reconnection is accomplished following a smoothly resynchronization of the local voltage with the MG, without disturbing the local loads supply. Additionally, this paper also discusses about the aspects related to the BESS management and its integration within the proposed system. The simulation and experimental results assess the feasibility of the proposed control solutions.

 

KEYWORDS

  1. Battery energy storage systems (BESS)
  2. Frequency control
  3. Inverter, microgrid (MG)
  4. Seamless transfer

 

SOFTWARE: MATLAB/SIMULINK

  

BLOCK DIAGRAM:

 

 

 

 

 

Fig. 1 BESS Structure

 

EXPECTED SIMULATION RESULTS:

 

 

 

 

 

Fig. 2. MG frequency (Top) and BESS active power (Bottom) for different operating conditions (simulation results).

 

 

 

 

 

Fig. 3 MG frequency (Top) and BESS active power (Bottom) for different levels of the local load compensation

 

CONCLUSION

This paper presented a Battery Energy Storage Systems BESS mainly designed to provide frequency support in MG, but having special control features. The BESS can operate both connected to the MG (G-mode) or in (I-mode), whereas the transition between the two states is seamlessly coordinated by an original control method. The BESS may serve local sensitive consumers connected on the local bus, by including special control functions to protect them in adverse MG operating conditions. The BESS management is also taking into discussion from the perspective of its influence upon the proposed controller performance. Simulations and experimental results were provided to validate the proposed BESS. An improved frequency controller, with conventional droop and virtual inertia was proposed and in the simulation results, it proved to be an efficient solution, resulting in faster damping of the MG frequency oscillations. Moreover, by partially or totally compensating the local loads, the MG is relieved by the corresponding power disturbance produced by their stochastic operation and thus the MG frequency deviation can be diminished.

By this approach, the BESS along with the local loads may be considered as a sort of smart load. The transition between G-mode to I-mode took place when the PCC power quality worsened and the experimental results showed a clean transfer without important voltage and frequency variations. The transition between I-mode to G-mode included a smoothly synchronization period of the local voltage with the MG voltage, after which the switching to G-mode did not disturb either the local loads or the MG. During I-mode, the local loads are supplied directly by the BESS and the presented experimental results including a comprehensive operating case, proved that the voltage control quality falls into the required standards. Future studies are intended to be carried out on the system availability to contribute to the MG power quality improvement.

 

REFERENCES

  • European Commission, Energy Roadmap 2050, 2011. [Online].Available: http://ec.europa.eu/energy/energy2020/roadmap/index_en.htm
  • Bevrani, A. Ghosh, and G. Ledwich, “Renewable energy sources and frequency regulation: Survey and new perspectives,” IET Renew. Power Gen., vol. 4, no. 5, pp. 438–457, Sep. 2010.
  • Tan, Q. Li, and H. Wang, “Advances and trends of energy storage technology in Microgrid,” Int. J. Elect. Power Energy Syst., vol. 44, no. 1, pp. 179–191, Jan. 2013.
  • Bottrell, M. Prodanovic, and T. C. Green, “Dynamic stability of a microgrid with an active load,” IEEE Trans. Power Electron., vol. 28, no. 11, pp. 5107–5119, Nov. 2013.
  • A. P. Lopes, F. J. Soares, and P. M. R. Almeida, “Integration of electric vehicles in the electric power system,” Proc. IEEE, vol. 99, no. 1, pp. 168–183, Jan. 2011.

Design and Analysis of an On-Board Electric Vehicle Charger for Wide Battery Voltage Range

ABSTRACT:

The scarcity of fossil fuel and the increased pollution leads the use of Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV) instead of conventional Internal Combustion (IC) engine vehicles. An Electric Vehicle requires an on-board charger (OBC) to charge the propulsion battery. The objective of the project work is to design a multifunctional on-board charger that can charge the propulsion battery when the Electric Vehicle (EV) connected to the grid. In this case, the OBC plays an AC-DC converter. The surplus energy of the propulsion battery can be supplied to the grid, in this case, the OBC plays as an inverter. The auxiliary battery can be charged via the propulsion battery when PEV is in driving stage. In this case, the OBC plays like a low voltage DC-DC converter (LDC). An OBC is designed with Boost PFC converter at the first stage to obtain unity power factor with low Total Harmonic Distortion (THD) and a Bi-directional DC-DC converter to regulate the charging voltage and current of the propulsion battery. The battery is a Li-Ion battery with a nominal voltage of 360 V and can be charged from depleted voltage of 320 V to a fully charged condition of 420 V. The function of the second stage DC-DC converter is to charge the battery in a Constant Current and Constant Voltage manner. While in driving condition of the battery the OBC operates as an LDC to charge the Auxiliary battery of the vehicle whose voltage is around 12 V. In LDC operation the Bi-Directional DC-DC converter works in Vehicle to Grid (V2G) mode. A 1KW prototype of multifunctional OBC is designed and simulated in MATLAB/Simulink. The power factor obtained at full load is 0.999 with a THD of 3.65 %. The Battery is charged in A CC mode from 320 V to 420 V with a constant battery current of 2.38 A and the charging is switched into CV mode until the battery current falls below 0.24 A. An LDC is designed to charge a 12 V auxiliary battery with CV mode from the high voltage propulsion battery.

KEYWORDS:

  1. Bi-directional DC-DC converter
  2. Boost PFC converter
  3. Electric vehicle
  4. Low voltage DC-DC converter
  5. Vehicle-to-grid

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig 1. Block Diagram of Power distribution in EV

EXPECTED SIMULATION RESULTS:

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

Fig 2.Simulated Results of Charging operation of the propulsion battery (a)Voltage and (b)Current in Beginning Point(c)voltage and (d)current in Nominal Point (e)voltage and (f)current in Turning Point(g)voltage and (h)current in End Point

Fig 3. DC link voltage and current during G2V operation (The current is multiplied by 100 for batter visibility)

Fig 4.Voltage and Current of Auxiliary battery during charging

(Current is multiplied by 10 for better visibility)

 CONCLUSION:

The second stage of OBC i.e. DC-DC converter is essential as it regulates the battery voltage and current. The most common method of charging Li-Ion batteries i.e. CC/CV mode charging is obtained by using a DC-DC converter in this chapter. The Battery is charged from 320 V to 420 V in a CC manner with a constant current of 2.38 A and further in a CV manner by keeping the battery voltage fixed at 420 V. The designed DC-DC converter supports Bi-directional power flow and the V2G mode of operation is simulated with the V2G controller, a new concept of LDC is designed here by utilizing the OBC to charge in Auxiliary battery from the propulsion battery. A single stage controller is developed in order to maintain a desired voltage across the Auxiliary battery.

REFERENCES:

[1] a. Emadi and K. Rajashekara, “Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles,” IEEE Trans. Ind. Electron., vol. 55, no. 6, pp. 2237–2245, 2008.

[2] M. Yilmaz and P. T. Krein, “Review of charging power levels and infrastructure for plug-in electric and hybrid vehicles,” 2012 IEEE Int. Electr. Veh. Conf. IEVC 2012, vol. 28, no. 5, pp. 2151–2169, 2012.

[3] H. Wang, S. Dusmez, and A. Khaligh, “Design and analysis of a full-bridge LLC-based PEV charger optimized for wide battery voltage range,” IEEE Trans. Veh. Technol., vol. 63, no. 4, pp. 1603–1613, 2014.

[4] P. Maheshwari, Y. Tambawala, H. S. V. S. K. Nunna, and S. Doolla, “A review of plug-in electric vehicles charging: Standards and impact on the distribution system,” Power Electronics, Drives and Energy Systems (PEDES), 2014 IEEE International Conference on. pp. 1–6, 2014.

[5] S. K. Sul and S. J. Lee, “Integral battery charger for four-wheel drive electric vehicle,” IEEE Trans. Ind. Appl., vol. 31, no. 5, pp. 1096–1099, 1995.

Space Vector Pulse Width Modulation Fed Direct Torque Control Of Induction Motor Drive Using Matlab-Simulink

ABSTRACT:

Now a day’s induction motor drives are highly demanding to design both mechanical and electrical drive system which is used widely in many industrial applications. Recent years many mathematical models for induction motor drive using Simulink models are employed. Scalar and Vector control method can be applied to induction motors in three phases symmetric as well as unsymmetrical two-phase form. The mathematical and Simulink operation of the induction motor drive can be studied and it is equivalent to a DC motor by the vector control method. With the combined performance of the numerical electronics and power electronics we are capable to smoothly control the variable speed and torque in low power industrial operations. With the help of technological achievements, several command and control techniques are developed by the technologists to control the time, flux and torque of the industrial electrical machine drives. The direct torque control (DTC) technique is one of the most advanced mechanisms in control operation of torque and speed. This technique with SVPWM gives fine regulation without rotational speed controlled feedback. The electromagnetic torque and stator flux are estimated in DTC technique only stator currents and voltage and it is independent of the parameters of the motor except for the Rs i.e. stator resistance [7].

KEYWORDS:

  1. Controller
  2. DTC
  3. IDM
  4. SVPWM and switching table.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig.1. DTC block diagram

EXPECTED SIMULATION RESULTS:

 

Fig.2. Electromagnetic torque

Fig.3. Rotor speed

Fig.4. Stator current

Fig.5. d-axis stator flux

Fig.6. q-axis stator flux

Fig.7. Electromagnetic torque

Fig.8. Rotor speed

Fig.9. Trajectory of direct axis stator and quadrature axis

flux (stationary reference frame)

Fig.10. Electromagnetic torque

Fig.11. Rotor speed

Fig.12. Direct axis stator flux

Fig.13. Quadrature axis stator flux

Fig.14. Direct axis stator current

Fig.15. Quadrature axis stator current

Fig.16. Stator flux trajectory

Fig.17. Rotor flux trajectory

CONCLUSION:

The proposed paper highlights to create a Simulink model of  DTC in induction motor drive. The DTC technique allows the decoupled control of torque and stator flux operate indipendently. The control process is simulated with the help of simpower system MATLAB Simulink block set and Sector determination with open-loop induction motor drive is obtained. In conventional DTC technique, high torque ripple is produced because the voltage space vector which are considered is applied for the whole switching period without considering the torque error value. This torque ripple can be minimized in order to achieve a smooth operation of the drive system and its performances, by changing the duty cycle ratio of the voltage vector which are selected during each switching cycle period, based on the stator flux position and torque error magnitude. This constitutes the basic of SVPWM technique. here simulate DTC scheme based on SVPWM technique and comparative study of conventional DTC-SVM scheme is derived and studied.

REFERENCES:

[1] Takahashi Isao, Noguchi Toshihiko, ,,’’A New Quick-Response IEEE Transactions on Industry Applications , Vol. IA-22No-5, Sept/Oct 1986.

 

Direct Torque Control of Brushless DC Drives With Reduced Torque Ripple

ABSTRACT:

The application of direct torque control (DTC) to brushless ac drives has been investigated extensively. This paper describes its application to brushless dc drives, and highlights the essential differences in its implementation, as regards torque estimation and the representation of the inverter voltage space vectors. Simulated and experimental results are presented, and it is shown that, compared with conventional current control, DTC results in reduced torque ripple and a faster dynamic response.

KEYWORDS:

  1. Brushless dc (BLDC) drives
  2. Direct torque control (DTC)
  3. Permanent-magnet motor

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Schematic of DTC BLDC drive.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulated results for Motor 1 (1500 r/min). (a) Phase-to-ground voltage. (b) Phase voltage. (c) Phase current. (d) Locus of stator flux linkage. (e) Electromagnetic torque.

Fig. 3. Simulated results for Motor 2 (400 r/min). (a) Phase-to-ground voltage. (b) Phase voltage. (c) Phase current. (d) Locus of stator flux linkage. (e) Electromagnetic torque.

CONCLUSION:

DTC has been applied to a BLDC drive, and its utility has been validated by simulations and measurements on two BLDC motors which have very different back-EMF waveforms. The main difference between the implementation of DTC to BLAC and BLDC drives is in the estimation of torque and the representation of the inverter voltage vectors. It has been shown that DTC is capable of instantaneous torque control and, thereby, of reducing torque pulsations.

REFERENCES:

[1] J. R. Hendershort Jr and T. J. E. Miller, Design of Brushless Permanent- Magnet Motors. Oxford, U.K.: Magana Physics/Clarendon, 1994.

[2] T. Kenjo and S. Nagamori, Permanent-Magnet and Brushless DC Motors. Oxford, U.K.: Clarendon, 1985.

[3] P. J. Sung,W. P. Han, L. H. Man, and F. Harashima, “A new approach for minimum-torque-ripple maximum-efficiency control of BLDC motor,” IEEE Trans. Ind. Electron., vol. 47, no. 1, pp. 109–114, Feb. 2000.

[4] C. French and P. Acarnley, “Direct torque control of permanent magnet drives,” IEEE Trans. Ind. Appl., vol. 32, no. 5, pp. 1080–1088, Sep./Oct. 1996.

[5] T. S. Low, K. J. Tseng, K. S. Lock, and K.W. Lim, “Instantaneous torque control,” in Proc. Fourth Int. Conf. Electrical Machines and Drives, Sep. 13–15, 1989, pp. 100–105.

A Novel Direct Torque Control Scheme for Induction Machines With Space Vector Modulation

ABSTRACT:

In this paper a new method for Direct Torque Control (DTC) based on load angle control is developed. The use of simple equations to obtain the control algorithm makes it easy tu understand and implement. Fixed switching frequency and low torque ripple are obtained using space vector modulation. This control strategy overcomes the must important drawbacks of classic DTC. Results shows the feasibility of the proposed method, obtaining good speed control bandwidth while overcoming classic DTC drawbacks.

 KEYWORDS:

  1. Electric Drives
  2. AC Machines
  3. Direct Torque Control
  4. Space Vector Modulation

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig.  1. Classic DTC control block diagram

EXPECTED SIMULATION RESULTS:

Fig. 2. Comparison of dynamic response klween DTC-SVM.F ield Oriented Control and Classic DTC. (a) Field Oriented Control. (b) Classic Direct Torque Control. (e) proposed Method.

Fig. 3. Torque response comparison between DTC-SVM and classic DTC. (a) Field Onenled Control, (h) Classic Direct Torque Control, (c) Proposed Method.

Fig. 4. Size of hysteresis band and sampling frequency effects on torque

ripple for clasic DTC.

Fig. 5. Torque spectral analJsis cornpanson. (a) DTC-SVM torque spectrum,

(b) Classic DTC torque spectrum.

Fig. 6. Stator Current during speed reversal.

 CONCLUSION:

The DTC-SVM strategy proposed in this work to control flux and torque is based on few induction machine fundamental equations. Consequently, the control method is simple and easy to implement. No coordinate rotation and less PI controllers than in field oriented control are needed. 0.1 (1.2 0.3 0.4 0.5 0.6 In addition, the proposed DTC strategy is well suited for use lime Is] in conjunction with space vector modulation resulting in a powerful alternative to overcome the well known drawbacks Fig. IO. Stator Current during speed reversal. of the original DTC solution: variable switching frequency and high torque ripple.

REFERENCES:

[1] F. Blaschke. “A New Method for the Estructural Decoupling of AC Induction Machines”. Cmj Rec. IFAC, Duessektorf. Genmny, pages 1-15, Oct. 1971.

[2] 1. Takahashi, Y. Ohmori. “High-Performance Direct Torque Control of an Induction Motor?. IEEE Trons. on Indu.~rriol Applicutions, 25(2):257- 262. MarcWApril 1989.

[3] M. Depenbmk. “Direct Self-Control (DSC) of Inverter-Fed Induction Machine”. IEEE Trans. on Power Elecrronicr. 3(4):42M29, October 1988.

[4] D. Casadei. G. Sera, A. Tani. “Implementation of a Direct Torque Control Algorithm for Induction Motors Based on Discrete Space Vector Modulation”. IEEE Trans. on Power Electronics. 15(4):769-777, July 2Mm.

[5] C. Manins, X. Roboarn. T.A. Meynard. A. Carvalho. “Switching frequency lmposition and Ripple Reduction in DTC Drives by Using a Multilevel Converer”. IEEE Trans. on Power Electmnicr. 17(2):28& 297, March 2002.