Grid-Connected Induction Motor Using a Floating DC-Link Converter Under Unbalanced Voltage Sag

ABSTRACT:

This article proposes a series compensator with unbalanced voltage sag ride-through capability applied to grid connected induction motors. A conventional three-phase voltage source inverter (VSI) is intended to regulate the motor voltages. The VSI is connected in series with the grid and a three-phase machine with open-ended windings. The proposed system is suitable for applications in which no frequency variation is required, like large pumps or fans. The VSI dc-link voltage operates as a floating capacitor through the energy minimized compensation (EMC) technique, in which there is no dc source or injection transformer. The motor load condition determines the minimum grid voltage positive component (sag severity) to keep EMC operation. Meanwhile, a voltage unbalance may increase the dc-link voltage requirements. A 1.5-hp four-pole induction motor has been used to verify the ride-through capability of the proposed compensator under grid voltage disturbances. A total harmonic distortion (THD) analysis of grid currents demonstrates that the proposed system provides low THD even if no passive filter is used. The operating principle, converter output voltage analysis, pulse width modulation technique, control strategy, and components ratings are discussed as well. Simulation and experimental results are presented to demonstrate the feasibility of the system.

KEYWORDS:

1.      Floating capacitor

2.      Induction motor

3.      Series compensator

4.      Unbalanced voltage sag

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

  

Fig. 1. Block diagram of feedback small-signal model.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation waveforms at the steady state and half load with perphase grid (vga ) and load (vla ) voltages, as well as the converter’s line-to-line voltage (vcab ).

Fig. 3. Simulation waveforms with the proposed series compensator under balanced voltage sag at half load. (a) Rated grid voltages. (b) Three-phase voltage sag of 80%.

Fig. 4. Simulation waveforms with the proposed series compensator under unbalanced voltage sag:Fd = 15%and half load. (a) Grid voltages and currents. (b) DC-link voltage, torque, and speed.

CONCLUSION:

The proposed system has unbalanced voltage sag ride-through capability, being suitable for grid-connected induction motors applications. Indeed, the simulation and experimental results supported the theoretical analysis. A conventional three-phase VSI using a floating dc-link capacitor has been applied as a series compensator. Besides that, the proposed system does not require any additional passive filter, injection transformer, or extra power supply. A conventional three-phase H-bridge converter to compensate balanced grid voltage disturbances has recently been proposed in the literature. Compared to the conventional solution, the proposed one has a lower number of components, a single dc link, and can deal with unbalanced voltages without a complex control strategy. The higher dc-link voltage requirement of the proposed series compensator was highlighted as its main drawback. Although the proposed solution provided higher THD of grid currents, its levels were acceptable. Hence, the proposed system can be easily integrated along with standard squirrel-cage induction motors when no frequency variation is required.

REFERENCES:

[1] H. G. Sarmiento and E. Estrada, “A voltage sag study in an industry with adjustable speed drives,” IEEE Ind. Appl. Mag., vol. 2, no. 1, pp. 16–19, Jan. 1996.

[2] K. Pietilainen, L. Harnefors, A. Petersson, and H. Nee, “DC-link stabilization and voltage sag ride-through of inverter drives,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1261–1268, Jun. 2006.

[3] A. H. Bonnett and H.M. Glatt, “Ten things you should know about electric motors: Their installation, operation, and maintenance,” IEEE Ind. Appl. Mag., vol. 24, no. 6, pp. 25–36, Nov. 2018.

[4] G.C. Jaiswal, M. S. Ballal, D. R. Tutakne, and H. M. Suryawanshi, “Impact of power quality on the performance of distribution transformers: A fuzzy logic approach to assessing power quality,” IEEE Ind. Appl.Mag., vol. 25, no. 5, pp. 8–17, Sep. 2019.

[5] “IEEE Recommended Practice for Monitoring Electric Power Quality”, IEEE Std 1159-2009 (Revision of IEEE Std 1159-1995), pp. c 1–81, Jun. 2009.

Current and Speed Sensor Fault Diagnosis Method Applied to Induction Motor Drive

ABSTRACT:

The paper proposes a novel approach based on a current space vector derived from measured stator currents to diagnose speed and current sensor failures in the field-oriented control of induction motor drives. A comparison algorithm between the reference and measured rotor speed is used to detect the speed sensor faults. A counter is added to eliminate the influence of the encoder noise in the diagnosis method. In this approach, estimated quantities are not used in the proposed speed sensor fault diagnosis strategy, which increases the independence between the diagnosis stages in the fault-tolerant control (FTC) method. Moreover, in order to discriminate between the speed sensor faults and the current sensor faults, a new approach combining the current space vector and a delay function is proposed to reliably determine the current sensor failures. The MATLAB-Simulink software was used to verify the idea of the proposed method. Practical experiments with an induction motor drive controlled by DSP  were performed to demonstrate the feasibility of this method in practice. The simulation and experimental results prove the effectiveness of the proposed diagnosis method for induction motor drives.

KEYWORDS:

1.      Fault-tolerant control

2.      Diagnosis

3.       Induction motor

4.       FOC

5.      Sensorless control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 

Figure 1. Block Diagram of FTC Unit.

 EXPECTED SIMULATION RESULTS:

 

Figure 2. Simulation Results - Speed Sensor Fault _ FTC.

Figure 3. Simulation Results _ Scaling Current Sensor Fault _ FTC.

 

 

Figure 4. Simulation Results _ Total Current Sensor Fault _ FTC.

 

CONCLUSION:

This paper presents a novel diagnosis method for the speed and current sensor fault-tolerant control of induction motor drives. The proposed method has proven its effectiveness in dealing with multi-type sensor failures. The speed sensor fault diagnosis algorithm can reliably detect the inaccuracy of the speed sensor signals without interference by random pulse noises. The loss of the current sensor signals, which is the most severe current sensor fault, is quickly detected by the delay-algorithm. Other types of current sensor failures is reliably identified without misunderstanding with a speed sensor fault. The proposed diagnosis algorithm is simpler than other existing detection methods, and thus, the computational hardware system executes faster as well as cheaper due to the lower calculation burden for the same operating conditions. The simulation and experimental results have demonstrated the efficiency of the proposed method. Further research can be implemented to improve the diagnosis of the sensor faults in transient states.

REFERENCES:

[1] A. Gouichiche, A. Safa, A. Chibani, and M. Tadjine, ``Global fault-tolerant control approach for vector control of an induction motor,'' Int. Trans. Electr. Energy Syst., vol. 30, no. 8, Aug. 2020, Art. no. e12440, doi: 10.1002/2050-7038.12440.

[2] D. Diallo, M. E. H. Benbouzid, and M. A. Masrur, ``Special section on condition monitoring and fault accommodation in electric and hybrid propulsion systems,'' IEEE Trans. Veh. Technol., vol. 62, no. 3, pp. 962_964, Mar. 2013, doi: 10.1109/TVT.2013.2245731.

[3] A. A. Amin and K. M. Hasan, ``A review of fault tolerant control systems: Advancements and applications,'' Measurement, vol. 143, pp. 58_68, Sep. 2019, doi: 10.1016/j.measurement.2019.04.083.

[4] A. Raisemche, M. Boukhnifer, C. Larouci, and D. Diallo, ``Two active fault-tolerant control schemes of induction-motor drive in EV or HEV,'' IEEE Trans. Veh. Technol., vol. 63, no. 1, pp. 19_29, Jan. 2014, doi:  10.1109/TVT.2013.2272182.

[5] Y. Azzoug, A. Menacer, R. Pusca, R. Romary, T. Ameid, and A. Ammar, ``Fault tolerant control for speed sensor failure in induction motor drive based on direct torque control and adaptive stator _ux observer,'' in Proc. Int. Conf. Appl. Theor. Electr. (ICATE), Oct. 2018, pp. 1_6.

Combined Speed and Current Terminal Sliding Mode Control with Nonlinear Disturbance Observer for PMSM Drive

ABSTRACT:

A terminal sliding mode control method based on nonlinear disturbance observer is investigated to realize the speed and current tracking control for PMSM drive system in this paper. The proposed method adopts the speed-current single-loop control structure instead of the traditional cascade control in the vector control of PMSM. Firstly, considering the nonlinear and the coupling characteristic, a single-loop terminal sliding mode controller is designed for PMSM drive system through feedback linearization technology. This method can make the motor speed and current reach the reference value in finite time, which can realize the fast transient response. Although the sliding mode control is less sensitive to parameter uncertainties and external disturbance, it may produce a large switching gain, which may cause the undesired chattering. Meanwhile, the sliding mode control cannot keep the property of invariance in the presence of unmatched uncertainties. Then, a nonlinear disturbance observer is proposed to the estimate the lump disturbance, which is used in the feed-forward compensation control. Thus, a composite control scheme is developed for the PMSM drive system. The results show that the motor control system based on the proposed method has good speed and current tracking performance and strong robustness.

KEYWORDS:

1.      PMSM drive

2.      Terminal sliding mode control

3.      Feedback linearization

4.      Nonlinear disturbance observer

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

Figure 1: Block Diagram Of PMSM Control System

 EXPECTED SIMULATION RESULTS:

 

Figure 2: The Motor Response Waveforms Of The Proposed Method: (A) Motor Speed (B) Dq-Axes Current (C) Phase Current

 

Figure 3: The Speed Waveforms Of Three Methods: (A) The Speed When The Motor Starts (B) The Speed With Load Disturbance

 

Figure 4: The Motor Waveforms With The Parameter Disturbance. (A) Motor Speed (B) Dq-Axes Current

 

 

Figure 5: The Contrastive Results With The Common Sliding Mode Control Method. (A) D-Axes Current (B) Q-Axes Current

 

CONCLUSION:

In this paper, a novel control method based on terminal sliding mode control through feedback linearization technology has been studied for PMSM drive system. The controller adopts the speed-current single-loop structure, which has the fast transient response. With the designed terminal sliding mode controller, the speed and current stabilizing control is achieved. Then, considering the lump disturbance in the drive system, a nonlinear disturbance observer is designed to deal with the mismatched disturbance, and it is used for the feed-forward compensation, and the robustness is improved effectively. Simulation results have proved that the controller has good robust performance and speed tracking performance under various conditions. But the speed and current control problems in the flux-weakening control areas are not considered at present, which will be the future research emphases.

REFERENCES:

 [1] J. Yu, P. Shi and L. Zhao, “Finite-time command filtered backstepping control for a class of nonlinear systems,” Automatica, vol. 2018, no. 92, pp. 173–180, Jun. 2018.

[2] T. Li and Y. V. Rogovchenko, “Oscillation criteria for second-order superlinear Emden–Fowler neutral differential equations,” Monatshefte f´l´zr Mathematik, vol. 184, no. 3, pp. 489–500, Apr. 2018.

[3] A. Darba, F. D. Belie and P. D. Haese, “Improved dynamic behavior in BLDC drives using model predictive speed and current control,” IEEE Trans. On Industrial Electronics, vol. 63, no. 2, pp. 728–740, Sep. 2016.

[4] X. Lang, M. Yang and J. Long, “A novel direct predictive speed and current controller for PMSM drive,” Proceedings of 8th International Power Electronics and Motion Control Conference, Hefei, China, pp. 2551–2556, May. 2016.

[5] S. Katsuji, M. Yoshitaka and I. Toshiyuki, “Singularity-free adaptive speed tracking control for uncertain permanent magnet synchronous motor,” IEEE Trans. On Power Electronics, vol. 31, no. 2, pp. 1692–1701, Apr. 2015.

Bidirectional Power Flow Control Integrated With Pulse and Sinusoidal-Ripple-Current Charging Strategies for Three-Phase Grid-Tied Converters

ABSTRACT:

The objective of this paper is to propose bidirectional charging/discharging strategies for three-phase grid-tied converters. The bidirectional power flow control feature of the converter is able to realize both charging and discharging capability. Besides, in order to achieve high charging efficiency as well as extend the life of the battery, five charging strategies are adopted and developed: 1) the constant current (CC) charging, 2) the pulse-ripple-current (PRC) charging, 3) the sinusoidal-ripple-current (SRC) charging, 4) the bidirectional pulse-ripple-current (BPRC) charging and 5) the bidirectional sinusoidal ripple- current (BSRC) charging. The direct quadrature (d-q) transformation is utilized for the converter to realize different charging methods. These methods can be achieved by the digital signal processor (DSP) without adding extra circuit components. In addition, the charging power differences between each strategy are considered and analyzed in this paper. Finally, both simulation and experimental results obtained from a 5-kW prototype circuit verify the performance and feasibility of the proposed bidirectional charger.

KEYWORDS:

1.      Three-phase grid-tied converter

2.      Bidirectional chargers

3.      Energy storage system

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

Figure 1. The Circuit Diagram And Control Blocks.

 EXPECTED SIMULATION RESULTS:

Figure 2. Simulation Waveforms Of The V_bat , I^bat , I_d;C_md , I_ac And V_ac With Different Charging Strategies (A) The CC Charging (B) The PRC Charging (C) The SRC Charging (D) The BPRC Charging (E) The BSRC Charging.

CONCLUSION:

This paper proposes a bidirectional three-phase grid-tied converter with charging/discharging strategies. The converter is able to be operated in the AC-DC (PFC) mode and the DC-AC (inverter) mode to realize the bidirectional power flow control feature. In order to increase the charging efficiency as well as extend the battery life, five charging strategies are considered and developed. Main contributions of this paper can be concluded as: 1) a three-phase AC-DC converter with bidirectional power flow control is developed, 2) five charging/ discharging strategies are integrated with the proposed charger, 3) detailed control concepts and operational principles are revealed with mathematical derivations and 4) the charging power analysis of different charging strategies is presented. These charging methods can be achieved by the proposed bidirectional converter with the d-q transformation concept. Moreover, comprehensive analysis and mathematical derivations of the charging power differences between each strategy are presented. Finally, both simulation and experimental results obtained from a 5-kW prototype demonstrate the performance and feasibility of the proposed bidirectional charger.

REFERENCES:

[1] K. Thirugnanam, S. K. Kerk, C. Yuen, N. Liu, and M. Zhang, ``Energy management for renewable microgrid in reducing diesel generators usage with multiple types of battery,'' IEEE Trans. Ind. Electron., vol. 65, no. 8, pp. 6772_6786, Aug. 2018.

[2] P. B. L. Neto, O. R. Saavedra, and L. A. de Souza Ribeiro, ``A dual-battery storage bank con_guration for isolated microgrids based on renewable sources,'' IEEE Trans. Sustain. Energy, vol. 9, no. 4, pp. 1618_1626, Oct. 2018.

[3] U. Manandhar, N. R. Tummuru, S. K. Kollimalla, A. Ukil, G. H. Beng, and K. Chaudhari, ``Validation of faster joint control strategy for battery- and supercapacitor-based energy storage system,'' IEEE Trans. Ind. Electron., vol. 65, no. 4, pp. 3286_3295, Apr. 2018.

[4] F. Wu, X. Li, F. Feng, and H. B. Gooi, ``Multi-topology-mode gridconnected inverter to improve comprehensive performance of renewable energy source generation system,'' IEEE Trans. Power Electron., vol. 32, no. 5, pp. 3623_3633, May 2017.

[5] Z. Zhang, Y.-Y. Cai, Y. Zhang, D.-J. Gu, and Y.-F. Liu, ``A distributed architecture based on microbank modules with self-recon_guration control to improve the energy ef_ciency in the battery energy storage system,'' IEEE Trans. Power Electron., vol. 31, no. 1, pp. 304_317, Jan. 2016.

An Improved Technique for Energy-Efficient Starting and Operating Control of Single Phase Induction Motors

ABSTRACT:

 The recent increase in electricity prices and the usage of single-phase induction motors (SPIMs)provide a stimulus for a focused research on energy-efficient optimization of SPIM load such as air-conditioners and refrigerators. Variable speed control of SPIM provides a promising way forward to reduce its power consumption. However, during variable speed operation under the popular constant V=f method, SPIM is required to operate at non-rated conditions. The operation of SPIM at non-rated conditions disturbs its symmetrical and balanced operation, thus degrading its efficiency. Moreover, soft-starting of SPIM at non-rated conditions is also challenging due to the resulting reduction in starting-torque. In this article, after a detailed analysis of SPIM energy-efficiency, an improved sensor-less optimal speed control strategy is developed to enable the symmetrical and balanced operation of SPIM at all the operating points over the entire speed-range to improve its performance. A novel algorithm, termed as the phase-shift algorithm, is also devised for efficient implementation of the proposed optimal speed control strategy. In addition, a unique framework for efficient soft-starting of SPIM at very low frequencies is also developed. The simulation-based results of the motor operated through the proposed phase-shift algorithm validate the energy-saving potential of the proposed control strategy.

KEYWORDS:

1.      Energy-efficient control

2.      Variable speed drives

3.      Speed-sensorless induction motor control

4.      Magnetic field control

5.      Inrush current reduction

6.      Starting torque

7.      Pulsating torque

8.      Energy savings in HVAC

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

Figure 1. Switching Pattern Generation Using The Phase-Shift Algorithm For Efficient Variable Speed Operation Of Spim.

EXPECTED SIMULATION RESULTS:

Figure 2. Simulation-Based Results Of Spim Operation Under The Proposed Optimal Control At F D 30 Hz.

Figure 3. Simulation-Based Results Of Spim Operation Under The Constant V =F Control Method At F D 30 Hz.

 

 

Figure 4. Simulation-Based Results Of Spim Operation Under The Proposed Optimal Control Strategy At F D 60 Hz.

 

Figure 5. Simulation-Based Results Of Spim Operation Under The Constant V =F Control Method At F D 60 Hz.

 

Figure 6. Simulation-Based Results Of Spim Operation Under The Proposed Optimal Control Strategy At F D 10 Hz.

 

 

Figure 7. Simulation-Based Results Of Spim Operation Under The Constant V =F Control Method At F D 10 Hz.

 

Figure 8. Simulation-Based Results Of Spim Soft-Starting At F D 10 Hz Under The Proposed Soft-Starting Strategy.

 

 

Figure 9. Simulation-Based Results Of Spim Soft-Starting At F D 10 Hz Under The Constant V =F Control Method.

 

CONCLUSION:

In this article, it is demonstrated that conventional techniques for speed control of SPIMs are inefficient because they cause the formation of elliptical magnetic fields inside them at non-rated starting and operating conditions. After a detailed analysis of SPIM energy-efficiency, a novel sensor-less con- trol strategy was devised to improve the performance at non-rated conditions by enabling the symmetrical and balanced operation of SPIM. Formation of circular magnetic field inside SPIMs over the entire speed range is achieved by dynamically and optimally controlling the auxiliary volt- age and phase-difference between the windings voltages simultaneously with constant V=f control using the developed phase-shift algorithm. Simulation-based evaluation of the optimal control strategy demonstrates an improvement of more than 400% in energy-efficiency as compared to maximum 18% reported in case of conventional SPIM energy-efficiency optimization techniques. The developed control algorithm also enables the soft-starting of SPIM with substantial starting torque at low-frequencies, resulting in a significant reduction in inrush current. Simulation-based results of the proposed sensor-less optimal control strategy confirm an inrush current reduction of more than 84%. This efficient soft-starting results in further energy-savings.

REFERENCES:

[1] J. C. Gomez, C. Reineri, G. Campetelli, and M. M. Morcos, ``A study of voltage sags generated by induction motor starting,'' Electr. Power Compon. Syst., vol. 32, no. 6, pp. 645_653, Jun. 2004.

[2] X. Wang, J. Yong, W. Xu, and W. Freitas, ``Practical power quality charts for motor starting assessment,'' IEEE Trans. Power Del., vol. 26, no. 2, pp. 799_808, Apr. 2011.

[3] Z. B. Duranay and H. Guldemir, ``Selective harmonic eliminated V/f speed control of single-phase induction motor,'' IET Power Electron., vol. 11,no. 3, pp. 477_483, Mar. 2018.

[4] A. Sampathkumar, ``Speed control of single phase induction motor using V/f technique,'' Middle-East J. Sci. Res., vol. 16, no. 12, pp. 1807_1812, 2013.

[5] E. R. Collins, ``Torque and slip behavior of single-phase induction motors driven from variable-frequency supplies,'' IEEE Trans. Ind. Appl., vol. 28, no. 3, pp. 710_715, May/Jun. 1992.