Indirect field-oriented control of induction motor drive based on adaptive fuzzy logic controller

ABSTRACT:  

Recently, Asynchronous Motors are extensively used as workhorse in a multitude of industrial and high performance applications. Induction Motors (IM) have wide applications in today’s industry because of their robustness and low maintenance. A smart and fast speed control system, however, is in most cases a prerequisite for most applications. This work presents a smart control system for IM using an Adaptive Fuzzy Logic Controller (AFLC) based on the Levenberg–Marquardt algorithm. A synchronously rotating reference frame is used to model IM. To achieve maximum efficiency and torque of the IM, speed control was found to be one of the most challenging issues. Indirect Field-Oriented Control (IFOC) or Indirect Vector Control techniques with robust AFLC offer remarkable speed control with high dynamic response. Computer simulation results using MATLAB/Simulink® Toolbox are described and examined in this study for conventional PI and AFLC. AFLC presents robustness as regards overshoot, undershoot, rise time, fall time, and transient oscillation for speed  variation of IFOC IM drive in comparison with classical PI. Moreover, load disturbance rejection capability for the designed control scheme is also verified with the AFL controller.

KEYWORDS:

1.      Induction Motor (IM)

2.      Indirect Field-Oriented Control (IFOC)

3.       Pulse Width Modulation (PWM)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Proposed system block diagram using AFLC

EXPERIMENTAL RESULTS:

Fig. 2 dq axis stator currents  for both AFLC & PI controller

Fig. 3 Stator phase voltage for both AFLC & PI controller

Fig. 4 Stator phase current for both AFLC & PI controller

Fig. 5 Rotor speed under variable load torque, a comparison of AFLC based on LM & PI

Fig. 6 dq-axis stator currents for both AFLC & PI controller

Fig. 7 Stator phase voltage for both AFLC & PI controller

Fig. 8 Stator phase current for both AFLC & PI controller

Fig. 9 Rotor speed under variable load torque, a comparison of AFLC based on LM & PI

Fig. 10 dq-axis stator currents for both AFLC & PI controller

Fig. 11 Stator phase voltage for both AFLC & PI controller

Fig. 12 Stator phase current for both AFLC & PI controller

 CONCLUSION:

In this paper, an Indirect Field-Oriented Control (IFOC) scheme for a drive system of three-phase induction motor is effectively investigated and validated using various simulation results in Matlab/Simulink. The performance of proposed controller is verified by introducing variation in speed and load torque. Simulation results demonstrate that PI has sluggish response compared to AFLC. In all load torque variations, the proposed AFLC shows robustness and continues to track the reference with small steady-state error. Moreover, AFLC based on LM is robust to model parameter variations, load variations and less sensitive to uncertainties and disturbances. The proposed scheme verifies superior and smoother performance with improved dynamic response.  Furthermore, the effectiveness of proposed AFLC is evaluated  and justified from performance indices IAE, ISE and ITAE.

REFERENCES:

1. Leonhard W (1996) Controlled AC drives, a successful transfer from ideas to industrial practice. Control Eng Pract 4(7):897–908

2. Fitzgerald AE,KingsleyCU, StephenD(1990) Electricmachinery, 5th edn. McGraw-Hill, New York

3. Marino R, Peresada S, Valigi P (1993) Adaptive input-output linearizing  control of induction motors. IEEE Trans Autom Cont 38(2):208–221

4. Leonhard W (1985) Control of electrical drives. Springer-, Berlin 

5. HeinemannG(1989) Comparison of several control schemes for ac induction motors. In: Proceedings of European Power Electronics Conference (EPE’89), pp 843–844

A New Switched-Capacitor Five-Level Inverter Suitable for Transformerless Grid-Connected Applications

ABSTRACT:  

 Transformerless grid-connected inverters have been extensively popular in renewable energy-based applications owing to some interesting features like higher efficiency, reasonable cost and acceptable power density. The major concern of such converters is the leakage current problem and also the step-down feature of the output voltage which causes a costly operation for a single stage energy conversion system. A new five-level transformerless inverter topology is presented in this study, which is able to boost the value of the input voltage and can remove the leakage current problem through a common-grounded architecture. Here, providing the five-level of the output voltage with only six power switches is facilitated through the series-parallel switching of a switched-capacitor module. Regarding this switching conversion, the self- voltage balancing of the integrated capacitors over a full cycle of the grid’s frequency can be acquired. Additionally, to inject a tightly controlled current to the local grid, a peak current controller-based technique is employed, which can regulate both the active and reactive power support modes. Theoretical analyses besides some experimental results are also given to corroborate the correct performance of the proposed topology.

KEYWORDS:

1.      Transformerless inverter

2.      Common ground type

3.      Switched Capacitor module and Grid connected applications

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. The overall block diagram of the controlled system.

 EXPERIMENTAL RESULTS:

Fig. 2. (a) Inverter’s output voltage (200 V/div) and the injected grid’s current (4 A/div) (b) Inverter’s output voltage (200V/div) and the local’s grid voltage (200V/div) (c) Injected grid’s current (4A/div) and local grid’s voltage (100 V/div) (d) the voltage across (200V/div) and the voltage across (100V/div). 2 C 1 C

Fig. 3.(a) The leading injected grid’s current (4 A/div) with the grid’s voltage (100 V/div) (b) The lagging injected grid current (4 A/div) with the grid’s voltage (100 V/div) (c) The grid’s voltage (blue trace) (200 V/div) and the injected grid current (green trace) (4 A/div) under the step-change of the PF from unity to a non-unity one.

Fig. 4. The measured current waveform through 1 C and 2 C (4 A/div).

Fig. 5. The measured PIV of power switches; (100 V/div) and (200 V/div). 1 2 / SS4 5 6 / / S S S

Fig. 6. The current stress waveforms of (a) (5 A/div) and (5 A/div), (b) (5 A/div), and (2 A/div) (c) (2 A/div) and (5 A/div). 1 S 2 S 3 S 6 S 4 S 5 S

Fig. 7. Dynamic performance of the proposed system under a voltage sag in the local grid’s voltage (a) The injected current (blue trace) (4 A/div) and the local grid’s voltage (red trace) (200 V/div) (b) The injected current (4 A/div) and the voltage across C1 (100 V/div) (c) The injected current (4 A/div) and the voltage across C2 (200 V/div).

CONCLUSION:

A new five-level SC-based transformerless grid-connected inverter has been presented in this study. The proposed topology is able to remove the leakage current concern with a common-grounded architecture. Also, with the reasonable number of active and passive involved elements, it offers a two times voltage boosting feature that makes it suitable for PV string applications. A PCC-based strategy has also been employed in following to regulate the value of the injected current. Details of such a controlled system besides some analysis as for the conduction losses, the design guidelines and voltage/current stresses of the switches were also given to further explore the performance of the proposed topology. Finally, a comprehensive comparative study alongside the experimental results of a 590 W built prototype have been presented to confirm the superiority and accurate operation of the proposed system.

REFERENCES:

[1] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Applicat., vol. 41, no. 5, pp. 1292-1306, Sep./Oct. 2005.

[2] M. Islam, S. Mekhilef, M. Hasan, “Single phase transformerless inverter topologies for grid-tied photovoltaic system: A review,” Renewable and Sustainable Energy Reviews, vol. 45, pp. 69-86, 2015.

[3] H. Xiao and S. Xie, “Leakage current analytical model and application in single-phase transformerless photovoltaic grid-connected inverter,” IEEE Trans. Electromagn. Compat., vol. 52, no. 4, pp. 902–913, Nov. 2010.

[4] D. Meneses, F. Blaabjerg, Ó Garcia, and Jo ´ se A. Cobos, “Review ´and comparison of step-up transformerless topologies for photovoltaic AC-module application,” IEEE Trans. Power Electron., vol. 28, no. 6, pp. 2649–2663, Jun. 2013.

[5] S. Saridakis, E. Koutroulis, F. Blaabjerg, “Optimization of SiC-Based H5 and Conergy-NPC Transformerless PV Inverters,” IEEE Emerg. Select. Topics Power Electron., vol. 3, no. 2, pp. 555-567, June. 2015.

A Seven-level Inverter with Self-balancing and Low Voltage Stress

ABSTRACT:  

Based on the switched-capacitor (SC) principle, a seven-level inverter is proposed, which can synthesize seven levels containing a single dc source. Moreover, it can further generate more levels by a cascaded extension. Meanwhile, the proposed topology does not require any sensor due to the use of SC technology. Furthermore, the capacitor voltage is self-balanced without utilizing the complicated control strategy and additional control circuits. The phase disposition pulse width modulation (PD-PWM) is adopted to reduce the total harmonic distortion (THD). The topology can generate the different levels with a wide range of modulation index. In addition, the topology can also work in over modulation. Compared with the traditional SC multilevel inverter (MLI), the absence of H-bridge makes low-voltage stress in proposed topology. The voltage stress of all switches is not more than the input voltage. Operational principles, modulation strategy, and voltage stress analysis are discussed. Simulation and experiment are conducted in low power to verify the feasibility of the proposed topology.

KEYWORDS:

1.      Multilevel inverters

2.       Low-voltage stress

3.      Switched-capacitor

4.      Voltage self-balancing

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. The circuit of the proposed seven-level inverter.

EXPERIMENTAL RESULTS:

Fig. 2. Simulation waveforms of the output voltage and current. (a) Output voltage and current. (b) THD of the output voltage.

CONCLUSION:

In this paper, the seven-level inverter is proposed by utilizing the switched capacitor technology. In addition, the inverter can be used as the basic cell to construct more output levels through a cascaded configuration. With the PD-PWM modulation, the capacitor voltage can be self-balanced without any sensor to detect the voltage. Moreover, the topology can work in different modulation index and can generate a different number of voltage levels. The working principle and capacitor parameters are analyzed in detail. In addition, the performances are compared with the existing topologies to prove the advantages. A low-power prototype is constructed to prove the feasibility of the proposed topology, and good performance of steady and transient state is testified.

REFERENCES:

[1] E. Samadaei, A. Sheikholeslami, S. A. Gholamian, and J. Adabi, “A Square T-Type (ST-Type) Module for Asymmetrical Multilevel Inverters,” IEEE Trans. Power Electron., vol. 33, no. 2, pp. 987–996, Feb. 2018.

[2] R. Barzegarkhoo, M. Moradzadeh, E. Zamiri, H. M. Kojabadi, and F. Blaabjerg, “A New Boost Switched-Capacitor Multilevel Converter with Reduced Circuit Devices,” IEEE Trans. Power Electron., vol. 33, no. 8, pp. 6738–6754, Aug. 2018.

[3] M. Norambuena, S. Kouro, S. Dieckerhoff, and J. Rodriguez, “Reduced Multilevel Converter: A Novel Multilevel Converter With a Reduced Number of Active Switches,” IEEE Trans. Ind. Electron., vol. 65, no. 5, pp. 3636–3645, May. 2018.

[4] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, J. Rodriguez, M. A. Pérez, and J. I. Leon, “Recent advances and industrial applications of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553–2580, Aug. 2010.

[5] A. Nabae, I. Takahashi, and H. Akagi, “A new neutral-point-clamped PWM inverter,” IEEE Trans. Ind. Appl., vol. IA-17, no. 5, pp. 518–523, Sep. 1981.

A Hybrid Boundary Conduction Modulation for a Single-Phase H-bridge Inverter to Alleviate Zero-Crossing Distortion and Enable Reactive Power Capability

ABSTRACT:  

Boundary Conduction Modulation (BCM) featuring zero voltage switching has caught researchers’ eyes recently. In single-phase full-bridge inverter with one leg operating in high switching frequency and one leg in line frequency, it is easy to achieve high conversion efficiency for low power applications. However, severe distortion will be introduced during zero voltage crossing area due to too low switching frequency around this area, and reactive power generation is not allowed under this modulation scheme due to zero voltage crossing issue. This paper proposes a hybrid BCM strategy for a single-phase full-bridge inverter to both alleviate voltage zero-crossing distortion and enable reactive power generation by reshaping the triangular waveform of inductor current into quadrangle waveform through rearranging the driving signals during voltage zero crossing area. This alleviates zero-crossing distortion by avoiding too low switching frequency and enables reactive power generation by employing the hybrid BCM around voltage zero crossing area. High efficiency can be maintained by combining the proposed hybrid BCM employed only for a small portion of zero crossing area and the conventional BCM for the rest. The principle of operation, theoretical analysis and simulation results are presented in this paper. A 300W microinverter prototype was built to verify the feasibility and effectiveness of the proposed hybrid BCM scheme.

KEYWORDS:

1.      Microinverter

2.      BCM operation

3.      Hybrid  modulation strategy

4.       High efficiency

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. The control diagram of the prototype proposed.

                

 EXPERIMENTAL RESULTS:

Fig. 2. The simulated wave forms of inverter operated in the proposed

control scheme (a) full load (b) half load.

Fig. 3. The simulated waveforms of BCM inverter when output reactive

power. (a)output current leads grid voltage 30o phase. (b)output current lags

grid voltage 30o phase.

Fig. 4. The detailed wave forms of hybrid BCM when output reactive power.

CONCLUSION:

This paper proposes a hybrid BCM for single-phase full bridge inverters to both overcome the current distortion at voltage zero-crossing region and have capability of reactive power generation. By combining the proposed hybrid BCM and unipolar BCM, the inverter will alleviate the current distortion without lowering efficiency. The hybrid modulation scheme is explained in details and the design considerations are also given for selecting control parameters and driving signal arrangement. To verify the proposed control scheme, a two-stage 300W microinverter prototype has been built. Simulation and experimental results verify the feasibility and effectiveness of the proposed control scheme.

 REFERENCES:

[1] Z. Zhang, X. F. He, and Y. F. Liu, “An optimal control method for  photovoltaic grid-tied-interleaved flyback microinverters to achieve high efficiency in wide load range,” IEEE Trans. Power Electron., vol. 28, no. 11,pp. 5074–5087, Nov. 2013.

[2] D. M. Scholten, N. Ertugrul, and W. L. Soong, “Micro-inverters in small scale PV systems: A review and future directions,” in Proc. Australas. Univ. Power Eng. Conf., Hobart, Tas., Australia, 2013, pp. 1–6.

[3] Z. Zhang, M. Chen, W. Chen, C. Jiang, and Z. Qian, “Analysis and implementation of phase synchronization control strategies for BCM  interleaved flyback microinverters,” IEEE Trans. Power Electron., vol. 29, no. 11, pp. 5921–5932, Nov. 2014.

[4] R. C. Beltrame, J. R. Zientarski, M. L. Martins, and J. R. Pinheiro, “Simplified zero-voltage-transition circuits applied to bidirectional poles: Concept and synthesis methodology,” IEEE Trans. Power Electron., vol. 26, no. 6, pp. 1765–1776, Jun. 2011.

[5] C. M. de Oliveira Stein, H. A. Grundling, H. Pinheiro, J. R. Pinheiro,  and H. L. Hey, “Zero-current and zero-voltage soft-transition commutation cell for PWM inverters,” IEEE Trans. Power Electron., vol. 19, no. 2, pp. 396–403, Mar. 2004.