Direct Torque Control Based on Space Vector Modulation with Adaptive Stator Flux Observer for Induction Motors

Direct Torque Control Based on Space Vector Modulation with Adaptive Stator Flux Observer for Induction Motors

ABSTRACT:

 This paper describes a combination of direct torque control (DTC) and space vector modulation (SVM) for an adjustable speed sensor less induction motor (IM) drive. The motor drive is supplied by a two-level SVPWM inverter. Using the IM model in the stator – axes reference frame with stator current and flux vectors components as state variables. In this paper, a conventional PI controller is designed accordingly for DTC-SVM system. Moreover, a robust full-order adaptive stator flux observer is designed for a speed sensor less DTC-SVM system and a new speed adaptive law is given. By designing the observer gain matrix based on state feedback control theory, the stability and robustness of the observer systems is ensured. Finally, the effectiveness and validity of the proposed control approach is verified by simulation results.

KEYWORDS:

1.     DTC

2.      Stator Flux Observer

3.     Torque Ripple

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig. 1 Block Diagram of DTC-SVM system

 CONCLUSION:

A novel DTC-SVM scheme has been developed for the IM drive system, In this control method, a SVPWM inverter is used to feed the motor, the stator voltage vector is obtained to fully compensate the stator flux and torque errors. Furthermore, a robust full-order adaptive flux observer is designed for a speed sensor-less DTC-SVM system. The stator flux and speed are estimated synchronously. By designing the constant observer gain matrix, the robustness and based on state feedback stability of the observer systems is ensured. Therefore, the proposed sensor-less drive system is capable of steadily working in very low speed, has much smaller torque ripple and exhibits good dynamic and steady-state performance.

REFERENCES:

[1] I. Takahashi and T. Noguchi, “A new quick-response and high efficiency control strategy of an induction motor,” IEEE Trans. Ind. Appl.,vol. IA-22, no. 5, pp. 820–827, 1986.

[2] Y. S. Lai and J. H. Chen, “A new approach to direct torque control ofinduction motor drives for constant inverter switching frequency andtorque ripple reduction,” IEEE Trans. Energy Convers., vol. 16, no. 3,pp. 220–227, 2001.

 [3] S. Mir, M. E. Elbuluk, and D. S. Zinger, “PI and fuzzy estimators for tuning the stator resistance in direct torque control of induction machines,” IEEE Trans. Power Electron., vol. 13, no. 2, pp. 279–287,1998.

[4] F. Bacha, R. Dhifaoui, and H. Buyse, “Real-time implementation ofdirect torque control of an induction machine by fuzzy logic controller,” in Proc. ICEMS, 2001, vol. 2, pp. 1244–1249.

[5] A. Arias, J. L. Romeral, and E. Aldabas, “Fuzzy logic direct torquecontrol,” in Proc. IEEE ISIE, 2000, vol. 1, pp. 253–258.

Simulation and Analysis of Zero Voltage Switching PWM Full Bridge Converter

Simulation and Analysis of Zero Voltage Switching PWM Full Bridge Converter

ABSTRACT:

In the conventional zero voltage switching full bridge converter the introduction of a resonant inductance and clamping diodes are introduced the voltage oscillation across the rectifier diodes is eliminated and the load range for zero-voltage switching (ZVS) achievement increases. When the clamping diode is conducting, the resonant inductance is shorted and its current keeps constant. So the clamping diode is hard turned-off, leading to reverse recovery loss if the output filter inductance is relatively larger. By introducing a reset winding in series with the resonant inductance to make the clamping diode current decay rapidly when it conducts this paper improves the full-bridge converter. The conduction losses are reduced by the use of reset winding. Also the clamping diodes naturally turn-off and avoids the reverse recovery. The proposed converter has been simulated for two different configurations and results have been compared. A 1 kW prototype converter is built to verify the operation principle and the experimental results are also demonstrated.

KEYWORDS:

1.      Clamping diodes

2.       full bridge converter

3.       Reset winding

4.       zero-voltage-switching (ZVS)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig: 1. Transformer-lag type ZVS PWM full bridge converter

Fig: 2. Transformer-lead type ZVS PWM full bridge converter

 CONCLUSION:

A ZVS PWM full-bridge converter is proposed in this paper, it employs an additional reset winding to make the clamping diode current decay rapidly when the clamping diode conducts, thus the conduction losses of the clamping diodes. The reset winding removes the need of auxiliary switches and the resonant inductance is reduced. The use of reset winding removes the need of hard switching for clamping diodes so there will not be any power loss due to switching of clamping diodes and the conversion efficiency will increased. In the meanwhile, the clamping diodes can be turned off naturally without reverse recovery over the whole input voltage range, and the output filter inductance can be designed to be large to obtain small current ripple, leading to reduced filter capacitance. Compared with the traditional full bridge converter, the proposed circuit provides another simple and effective approach to avoid the reverse recovery of the clamping diodes. The structure and operation of the proposed ZVS PWM full-bridge converter with reset winding topology are described and two configurations have been studied i.e. Transformer leading and Transformer-Lagging connections. We have studied the performance of both the configuration. If we compare the rectifier output in both the case we find that Tr-Lag connection produces less ripples. Transformer lagging configuration is advisable for more accurate results.

REFERENCES:

 [1] B.P. Mcgrath, D.G. Holmes, McGoldrick and A.D. Mclve, “Design of a soft-switched 6-kW battery charger for traction applications,” IEEE Trans. Power Electron, vol.22,no. 4, pp. 1136-1144, Jull. 2007.

[2] J. Dudrick, P. Spanik and N.D. Trip, “Zero-voltage and zero-current switching full-bridge dc-dc converter with auxiliary transformer,” IEEE Trans. Power Electron, vol.21, no.5, pp.1328-1335, Sep. 2006.

[3] J.Zhang, X. Xie, X. Wu, G. Wu and Z. Qian, “ A novel zero-current transition full bridge dc-dc converter,” IEEE Trans. Power Electron, vol. 21, no. 2, pp. 354-360, Mar. 2006.

[4] Darlwoo Lee, Taeyoung Abu, Byungcho Choi, “A new soft switching dc-to-dc converter employing two transformer”, . PESC, pp. 1-7, June 2006.

[5] Xinyu Xu Ashwin M. Khambadkhone, Toh Meng Leong, Ramesh Oruganti, “ A 1 MHz zero-voltage switching asymmetrical half bridge dc/dc converter: analysis and design” IEEE Trans. Power Electron, vol.21, no. 1, pp. 105-113, Jan. 2006.

High-Step-Up and High-Efficiency Fuel-Cell Power-Generation System With Active-Clamp Flyback–Forward Converter

High-Step-Up and High-Efficiency Fuel-Cell Power-Generation System With Active-Clamp Flyback–Forward Converter

ABSTRACT:

A high-efficiency fuel-cell power-generation system with an active-clamp flyback–forward converter is presented in this paper to boost a 12-V dc voltage into a 220-V 50-Hz ac voltage. The proposed system includes a high-efficiency high-step-up interleaved soft-switching flyback–forward converter and a full-bridge inverter. The front-end active-clamp flyback–forward converter has the advantages of zero-voltage-switching performance for all the primary switches, reverse-recovery-problem alleviation for the secondary output diodes, large voltage-conversion ratio, and small input-current ripple. Furthermore, there are two coupled inductors in the proposed converter. Each coupled inductor can work in the flyback mode when the corresponding main switch is in the turn-on state and in the forward mode when it is in the turnoff state, which takes full use of the magnetic core and improves the power density. In addition, the full-bridge inverter with an LC low-pass filter is adopted to provide low-total-harmonic-distortion ac voltage to the load. Therefore, high-efficiency and high-power density conversion can be achieved in a wide input-voltage range by employing the proposed system. Finally, a 500-W prototype and another 1-kW converter are implemented and tested to verify the effectiveness of the proposed system.

 KEYWORDS:

1.      Active clamp

2.       Fly back–forward converter

3.       Fuel cell generation system.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Proposed high-efficiency fuel-cell power-generation system

CONCLUSION:

In this paper, an interleaved high-step-up ZVS flyback– forward converter has been proposed for the fuel-cell power generation system. The voltage doubler rectifier structure is employed to provide a large voltage-conversion ratio and to remove the output-diode reverse-recovery problem. Furthermore, ZVS soft-switching operation is realized for all the primary active switches to minimize the switching losses. In addition, the input-current ripple is small due to the interleaved operation and the current-fed-type configuration. The steady state operation analysis and the main circuit performance are discussed to explore the advantages of the proposed converter in a high-efficiency high-step-up power-generation system. Finally, a 500-W 12-V dc to 220-V ac system is employed and another 1-kW prototype operated at 100 kHz is tested as examples to illustrate the important design guidelines of the proposed converter. Experimental results have demonstrated that the proposed system is an excellent power-converter system for fuel-cell applications, featuring high efficiency, high-step up ratio, and high power density.

REFERENCES:

[1] S. Jemei, D. Hissel, M. C. Pera, and J. M. Kauffmann, “A new modeling approach of embedded fuel-cell power generators based on artificial neural network,” IEEE Trans. Ind. Electron., vol. 55, no. 1, pp. 437–447, Jan. 2008.

[2] M. H. Todorovic, L. Palma, and P. N. Enjeti, “Design of a wide input range dc–dc converter with a robust power control scheme suitable for fuel cell power conversion,” IEEE Trans. Ind. Electron., vol. 55, no. 3, pp. 1247–1255, Mar. 2008.

[3] K. Jin,M. Yang, X. Ruan, and M. Xu, “Three-level bidirectional converter for fuel-cell/battery hybrid power system,” IEEE Trans. Ind. Electron., vol. 57, no. 6, pp. 1976–1986, Jun. 2010.

[4] C. T. Pan and C. M. Lai, “A high-efficiency high step-up converter with low switch voltage stress for fuel-cell system applications,” IEEE Trans. Power Electron., vol. 57, no. 6, pp. 1998–2006, Jun. 2010.

[5] E. H. Kim and B. H. Kwon, “Zero-voltage- and zero-current-switching full-bridge converter with secondary resonance,” IEEE Trans. Ind. Electron., vol. 57, no. 3, pp. 1017–1025, Mar. 2010.

Dynamic Modeling of Microgrid for Grid Connected and Intentional Islanding Operation

Dynamic Modeling of Microgrid for Grid Connected and Intentional Islanding Operation

ABSTRACT:

Microgrid is defined as the cluster of multiple distributed generators (DGs) such as renewable energy sources that supply electrical energy. The connection of microgrid is in parallel with the main grid. When microgrid is isolated from remainder of the utility system, it is said to be in intentional islanding mode. In this mode, DG inverter system operates in voltage control mode to provide constant voltage to the local load. During grid connected mode, the Microgrid operates in constant current control mode to supply preset power to the main grid. The main contribution of this paper is summarized as

1) Design of a network based control scheme for inverter based sources, which provides proper current control during grid connected mode and voltage control during islanding mode.

2) Development of an algorithm for intentional islanding detection and synchronization controller required during grid reconnection.

3) Dynamic modeling and simulation are conducted to show system behavior under proposed method using SIMULINK.

From the simulation results using Simulink dynamic models, it can be shown that these controllers provide the microgrid with a deterministic and reliable connection to the grid.

KEYWORDS:

1.      Distributed generation (DG)

2.       grid connected operation

3.       intentional islanding operation and islanding detection

4.       Microgrid

5.       Synchronization

6.       voltage source converter (VSC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1. Dynamic model of microgrid with controller.

CONCLUSION:

Current and voltage Control techniques have been developed for grid connected and intentional islanding modes of operation using PI controllers. An intentional islanding detection algorithm responsible for switching between current control and voltage control is developed using logical operations and proved to be effective. The reconnection algorithm coupled with the synchronization controller enabled the DG to synchronize itself with the grid during grid reconnection. The performance of the microgrid with the proposed controllers and algorithms has been analyzed by conducting simulation on dynamic model using SIMULINK. The simulation results presented here confirms the effectiveness of the control scheme.

REFERENCES:

[1] L. Shi, M.Y. Lin Chew. “A review on sustainable design of renewable energy systems,” science direct journal present in Renewable and Sustainable Energy Reviews, Vol. 16, Issue 1, 2012, pp. 192–207.

[2] Q. Lei, Fang Zheng Peng, Shuitao Yang. “Multi loop control method for high performance microgrid inverter through load voltage and current decoupling with only output voltage feedback,” IEEE Trans. power. Electron, vol. 26, no. 3, 2011, pp. 953–960.

[3] J. Selvaraj and N. A. Rahim, “Multilevel inverter for grid-connected PV system employing digital PI controller,” IEEE Trans. Ind. Electron., vol. 56, no. 1, 2009, pp. 149–158.

[4] I. J. Balaguer, Fang Zheng Peng, Shuitao Yang, Uthane Supatti Qin Lei. “Control for grid connected and intentional islanding modes of operations of distributed power generation,” IEEE Trans. Ind. Electron., vol. 56, no. 3, 2009, pp. 726–736.

[5] R. J. Azevedo, G.I. Candela, R. Teodorescu, P.Rodriguez , I.E-Otadui “Microgrid connection management based on an intelligent connection agent,” 36th annual conference on IEEE industrial electronics society, 2010, pp. 3028–3033. 

A ZVS Grid-Connected Three-Phase Inverter

A ZVS Grid-Connected Three-Phase Inverter

ABSTRACT:

A six-switch three-phase inverter is widely used in a high-power grid-connected system. However, the anti parallel diodes in the topology operate in the hard-switching state under the traditional control method causing severe switch loss and high electromagnetic interference problems. In order to solve the problem, this paper proposes a topology of the traditional six-switch three-phase inverter but with an additional switch and gave a new space vector modulation (SVM) scheme. In this way, the inverter can realize zero-voltage switching (ZVS) operation in all switching devices and suppress the reverse recovery current in all anti parallel diodes very well. And all the switches can operate at a fixed frequency with the new SVM scheme and have the same voltage stress as the dc-link voltage. In grid-connected application, the inverter can achieve ZVS in all the switches under the load with unity power factor or less. The aforementioned theory is verified in a 30-kW inverter prototype.

KEYWORDS:

1.      Grid connected

2.       soft switching

3.       space vector modulation (SVM)

4.       three-phase inverter

5.       zero-voltage switching (ZVS)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1.Soft-switching three-phase inverter topology: (a) dc-side topology and (b) ac-side topology.

CONCLUSION:

The analysis and experimentation presented verify that the SVM-controlled three-phase soft-switching grid-connected inverter can realize ZVS operation for all switching devices, and the reverse recovery current in the antiparallel diodes of all switching devices is suppressed well. SVM can be realized at the fixed switching frequency. And the switching voltage stress across all the power switch devices is the same as the dc-link voltage. The ZVS can be achieved in the grid-connected ZVS inverters under the load with unity power factor or less. The reduced switching loss increases its efficiency and makes it suitable for practical applications.

REFERENCES:

[1] N. Mohan, T. Undeland, andW. Robbins, Power Electronics: Converters, Applications and Design. New York: Wiley, 2003, pp. 524–545.

[2] M. D. Bellar, T. S. Wu, A. Tchamdjou, J. Mahdavi, and M. Ehsani, “A review of soft-switched DC–AC converters,” IEEE Trans. Ind. Appl., vol. 34, no. 4, pp. 847–860, Jul./Aug. 1998.

[3] D. M. Divan, “Static power conversion method and apparatus having essentially zero switching losses and clamped voltage levels,” U.S. Patent 48 64 483, Sep. 5, 1989.

[4] M. Nakaok, H. Yonemori, and K. Yurugi, “Zero-voltage soft-switched PDM three phase AC–DC active power converter operating at unity power factor and sinewave line current,” in Proc. IEEE Power Electronics Spec. Conf., 1993, pp. 787–794.

[5] H. Yonemori, H. Fukuda, and M. Nakaoka, “Advanced three-phase ZVSPWM active power rectifier with new resonant DC link and its digital control scheme,” in Proc. IEE Power Electron. Variable Speed Drives, 1994, pp. 608–613.

Research on Three-phase Voltage Type PWM Rectifier System Based on SVPWM Control

Research on Three-phase Voltage Type PWM Rectifier System Based on SVPWM Control

ABSTRACT:

The fundamental principle of SVPWM is introduced in this study. The design on the structure of three phase voltage type PWM rectifier system based on SVPWM control was also discussed. Then we calculate the DC capacitor and AC side inductance. The computer simulation tool MATLAB/Simulink is taken and the result is shown in the end. The result indicates that the design of such platform is feasible.

KEYWORDS:

1.      Power factor

2.       PWM rectifier

3.       space voltage vector

4.       three-phase voltage

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1: The three phase PWM rectifier voltage fixed vector control diagram

CONCLUSION:

This study introduces SVPWM control principles and adopts three-phase PWM rectifier digital control system based on SVPWM control on the basis of this. Besides, AC-side incoming inductance and DC-side capacitance are calculated and selected. Then, each simulation module is established for the whole system by use of simulation software MATLAB/Simulink and simulation researches are conducted. The simulation result shows the digital control system designed is feasible.

REFERENCES:

 Boon, T.O. and W. Xiao, 1990. Voltage angle lock loop control of the boost type PWM converter for HVDC application [J]. IEEE Tran. Power Elec., 5(2): 229-235.

Fujita, H., Y. Watanabe and H. Akayi, 1998. Control and ana1ysis of a unified power flow controller [J]. IEEE PELS, 98: 805-811.

Li, Z., J. Wang and L. Huade, 2006. Review on nonlinear control strategies of three phase boosttype PWM rectifiers. Electric Drive, 36(1): 9-13.

Marian, P.K. and M. Luigi, 1998. Current control techniques for three-phase voltage-source PWM converters [J]. A survey. IEEE Trans. Power Elec., 45(5): 508-515.

Mariusz, M., M. Jasin’ski and P.K. Marian, 2004. Simple direct power control of three-phase PWM  rectifier using space-vector modulation [J]. IEEE Trans. Ind. Elec., 51(2): 447-454.

Simulation Analysis of SVPWM Inverter Fed Induction Motor Drives

Simulation Analysis of SVPWM Inverter Fed Induction Motor Drives

ABSTRACT:

In this paper represent the simulation analysis of space vector pulse width modulated(SVPWM) inverter fed Induction motor drives. The main objective of this paper is analysis of Induction motor with SVPWM fed inverter and harmonic analysis of voltages & current. for control of IM number of Pulse width modulation (PWM) schemes are used to for variable voltage and frequency supply. The most commonly used PWM schemes for three-phase voltage source inverters (VSI) are sinusoidal PWM (SPWM) and space vector PWM (SVPWM). There is an increasing trend of using space vector PWM (SVPWM) because of it reduces harmonic content in voltage, Increase fundamental output voltage by 15% & smooth control of IM. So, here present Modeling & Simulation of SVPWM inverter fed Induction motor drive in MATLAB/SIMULINK software. The results of Total Harmonic Distortion (THD), Fast Fourier Transform (FFT) of current are obtained in MATLAB/Simulink software.

KEYWORDS:

1.      Inverter

2.       VSI

3.       SPWM

4.       SVPWM

5.       IM drive

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1 Simulation Block Diag. of SVPWM Three level inverter with IM load

CONCLUSION:

The SVPWM Inverter fed induction motor drive Modeling & then simulation is done in MATLAB/SIMULINK 12. From simulation results of THD & FFT analysis concluded that SVPWM technique is better over all PWM techniques which gives less THD in Inverter current 4.89%., which under the permissible limit.

REFERENCES:

 [1] A. R. Bakhshai H. R. Saligheh Rad G. Joos, space vector modulation based on classification method in three-phase multi-level voltage source inverters, IEEE 2001

[2] Bimal K Bose, modern power electronics and ac drives © 2002 Prentice hall ptr.

[3] Dorin O. Neacsu, space vector modulation –An introduction tutorial at IECON2001 IEEE 2001

[4] Fei Wang, Senior Member, “Sine-Triangle versus Space-Vector Modulation for Three-Level PWM Voltage-Source Inverters”, IEEE transactions on industry applications, vol. 38, no. 2, March/April 2002. The 27th Annual Conference of the IEEE Industrial Electronics Society

[5] F. Wang, Senior, Sine-Triangle vs. space vector modulation for three-level voltage source inverters ,IEEE 2000