A Position Sensorless Control Strategy for BLDCM Based on Flux-Linkage Function

 ABSTRACT:

 A novel sensorless control strategy for the brushless DC motor (BLDCM) is proposed in this paper. The proposed strategy is realized by employing new flux-linkage functions, and can be applied to drive the sensorless BLDCM in the high speed and low speed ranges with highly accurate and reliable commutation. Another attractive feature is that the jumping edges of the flux-linkage functions are utilized to determine the commutation points, so there is no threshold needed as comparing with other sensorless control methods. In addition, the three-phase current control method is adopted, and terminal voltages in flux-linkage function expressions can be easily obtained by calculation. By this way, the sample delay and the influence of the floating phase voltage can be eliminated which can improve the accuracy and reliability of the sensorless control strategy. The effectiveness of the proposed strategy is verified by experimental results.

KEYWORDS:

1.      Brushless dc motor

2.      Flux-linkage function

3.      Sensorless

4.      Rotor position.

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, a novel flux-linkage function was constructed. The relationship between the flux-linkage function and the commutation point has been analyzed, and the jumping edge is used to estimate the commutation point. A rotor-position table is established, and then the sensorless control principle of the flux-linkage function is illustrated. In conclusion, the proposed strategy has the following advantages.

1) The flux-linkage function is constructed by using the line to line PM flux linkage, whose magnitude is almost constant during the operation. At the same time, the waveform of the flux-linkage function is identical, so the proposed method is suitable for the high speed and low speed ranges and has a small commutation error.

2) The commutation point is obtained by the jumping edge of flux-linkage function without setting commutation threshold, which can reduce the commutation error caused by the unreasonable threshold setting. Meanwhile, the flux-linkage function is significantly large near extreme points, which makes it easier to detect the commutation point.

3) The three-phase current control method is adopted, so the terminal voltage of the flux-linkage function is calculated by the switching state of the power transistor. Therefore, the sampling circuit is not needed, and the error caused by sampling is avoided.

REFERENCES:

[1] C. L. Xia, G. K. Jiang, W. Chen, and T. N. Shi, “Switching-gain adaption current control for brushless DC Motors,” IEEE Trans. Ind. Electron., vol. 63, no. 4, pp. 2044–2052, Apr. 2016.

[2] C. L. Xia, Y. F. Wang, and T. N. Shi, “Implementation of finite-state model predictive control for commutation torque ripple minimization of permanent-magnet brushless DC motor,” IEEE Trans. Ind. Electron., vol.60, no.3, pp. 896–905, Mar. 2013.

[3] T. N. Shi, Y. T. Guo, P. Song, and C. L. Xia, “A new approach of minimizing commutation torque ripple for brushless DC motor based on DC-DC converter,” IEEE Trans. Ind. Electron., vol.57, no.10, pp. 3483–3490, Oct. 2010.

[4] J. C. Moreira, “Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range,” IEEE Trans. Ind. Appl., vol. 32, no. 6, pp. 1394–1401, Nov./Dec. 1996.

[5] J. X. Shen, Z. Q. Zhu, and D. Howe, “Sensorless flux-weakening control of permanent-magnet brushless machines using third harmonic back emf,” IEEE Trans. Ind. Appl., vol. 40, no. 6, pp. 1629–1636, Nov./Dec. 2004.

A New Method to Minimize Overall Torque Ripple in the Presence of Phase Current Shift Error for Three-Phase BLDC Motor Drive

ABSTRACT:

 

Torque ripple is always problematic in brushless dc (BLDC) motor drive. It is caused by nonsymmetric commutating phase current rate and phase current shift error. The latter is inevitable even in the latest sensor/sensorless BLDC motor control and drive. In this paper, a simple, robust, and low-cost method of minimizing overall torque ripple in the presence of phase current shift error is presented. It works and manages well to maintain the torque ripple increase within 10% even with 27° phase current shift, compared with more than 25% torque ripple increase without any compensator. The proposed technique is theoretically elucidated in detail, and the performance is verified via MATLAB/Simulink simulation and experiments.

KEYWORDS:

1.      Brushless rotating machines

2.      Dc motor drives

3.      Inverters

4.      Minimization methods

5.       Phase shifters

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, the proposed method reveals its suitability for reducing overall torque ripple caused by phase current shift error and nonsymmetric commutating phase currents. The proposed method is simulated with MATLAB/Simulink and experimentally verified. It reduces overall torque ripple for the BLDC drive system if any phase current shift error occurs.

REFERENCES:

[1] G.-J. Su and J. W. McKeever, “Low-cost sensorless control of brushless DC motors with improved speed range,” IEEE Trans. Power Electron., vol. 19, no. 2, pp. 296–302, Mar. 2004.

[2] K. Tabarraee, J. Iyer, S. Chiniforoosh, and J. Jatskevich, “Comparison of brushless DC motors with trapezoidal and sinusoidal back-EMF,” in Proc. 24th Can. Conf. Elect. Comput. Eng. (CCECE), Niagara Falls, ON, Canada, May 2011, pp. 803–806.

[3] H. Lu, L. Zhang, and W. Qu, “A new torque control method for torque ripple minimization of BLDC motors with un-ideal back EMF,” IEEE Trans. Power Electron., vol. 23, no. 2, pp. 950–958, Mar. 2008.

[4] Y.-K. Lin and Y.-S. Lai, “Pulsewidth modulation technique for BLDCM drives to reduce commutation torque ripple without calculation of commutation time,” IEEE Trans. Ind. Appl., vol. 47, no. 4, pp. 1786–1793, Jul./Aug. 2011.

[5] J. Shi and T.-C. Li, “New method to eliminate commutation torque ripple of brushless DC motor with minimum commutation time,” IEEE Trans. Ind. Electron., vol. 60, no. 6, pp. 2139–2146, Jun. 2013

A Direct Redundancy approach to Fault Tolerant Control of BLDC Motor with a damaged Hall-effect Sensor

 ABSTRACT:

 Often for closed loop operation of a Brushless direct current (BLDC) motor, Hall-effect sensors are used and recently theirs been a number of papers discussing Fault Tolerant Control (FTC) of the BLDC motor for a defective Hall-effect sensor. However, so far direct redundancy based approach for FTC of BLDC motor for a position sensor fault is not presented. This paper, contributes a direct redundancy based method by utilizing redundant Hall-effect sensors for FTC of BLDC motor. Redundant Hall-effect sensors generate additional transitions resulting in faster fault detection. To verify the proposed idea, Matlab/Simulink model is developed and the simulation results are presented by programing a Matlab function block acting as a fault tolerant controller. Furthermore, the algorithm is implemented into the MicroLabBox for experimental validation and the results are discussed.

KEYWORDS:

1.      Brushless machines

2.      Fault Tolerant Control

3.      Hall-effect devices

4.      Position measurement

5.       Signal Reconstruction

6.      Redundancy

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

Transitions of the redundant Hall-effect sensors provide supplementary opportunities to detect faults within electrical 30° or in worst case in electrical 45° and therefore the proposed FTC method results in faster fault compensation times as the experimental results show that the compensation is done in less than electrical 30°. Compared to other FTC methods that use Fourier coefficients and FFT calculations, requiring high end digital signal processors, this method offers less complexity, improved compensation time, and reduces the computational costs, however, use of direct redundancy does increase the system cost slightly. And furthermore, in recent research, for constant speed operation of BLDC motor, the Hall-effect sensor transitions are assumed to be equally spaced, however, experiments showed that transitions are not equally spaced, which makes implementation of the FTC process more complicated. To name a few reasons, there can be misaligned Hall-effect sensors, or cogging torque. Since the redundant sensor method presented here only considers the Hall-effect sensor signals, in that matter, the method presented in this paper offers robustness and simplicity.

REFERENCES:

[1]. J. Chiasson, Modeling and High-Performance Control of Electric Machines, Wiley-Interscience, 2005.

[2]. A. Tashakori and M. Ektesabi, "A simple fault tolerant control system for hall effect sensors failure of BLDC motor," in IEEE ICIEA, Melbourne, 2013.

[3]. Q. Zhang and M. Feng, "Combined commutation optimisation strategy for brushless DC motors with misaligned hall sensors," IET Electric Power Applications, vol. 12, no. 3, 2017.

[4]. X. Song, J. Fang and B. Han, "High-precision rotor position detection for high-speed surface PMSM drive based on linear hall-effect sensors," IEEE Transactions on Power Electronics, vol. 31, no. 7, July 2016.

[5]. S.-Y. Kim, C. Choi, K. Lee and W. Lee, "An improved rotor position estimation with vector-tracking observer in PMSM drives with low-resolution hall-effect sensors," IEEE Transactions on Industrial Electronics, vol. 58, no. 9, 2011.

 

A Commutation Torque Ripple Suppression Strategy for Brushless DC Motor Based on Diode-Assisted Buck-Boost Inverter

 ABSTRACT:

 

Based on diode-assisted buck-boost inverter, this paper proposes a new commutation torque ripple suppression strategy for brushless DC motor (BLDCM). Four types of switching vectors are constructed, according to the working pattern of the diode-assisted inverter and the operation mode of the BLDCM. Moreover, the effects of switching vector combination on commutation torque ripple suppression and motor speed regulation are analyzed in the commutation and normal conduction periods, respectively. Based on this analysis, the duration of switching vectors within each modulation cycle is derived and the sequence of vectors is arranged at the same time in these two periods. The proposed method can effectively suppress the commutation torque ripple over the full speed range by unified switching vectors during the commutation period, without needing to switch control strategies according to the speed range. In addition, the increase of the voltage stress of switching devices in the inverter bridge can be avoided by designing the duration and sequence of switching vectors during the commutation and normal conduction periods. The effectiveness of the presented method is validated by the experimental results.

KEYWORDS:

1.      Brushless DC motor

2.      Commutation torque ripple reduction

3.      Diode-assisted buck-boost inverter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a new commutation torque ripple suppression strategy is proposed based on the diode-assisted boost-buck inverter. This strategy has the following advantages:

1) The proposed method can effectively improve the utilization of DC supply voltage, and it is promising for the industrial applications supplied by low-voltage DC source such as fuel cell, lithium battery, and photovoltaic array.

2) The commutation torque ripple over the full speed range can be suppressed effectively under the proposed method, without needing to switch control strategies according to the speed range.

3) By designing the duration and sequence of the large vector, small vector and zero vector, the increase of the voltage stress of switching devices in the inverter bridge can be avoided during the commutation and normal conduction periods.

4) Compared with the methods of adding a DC-DC converter, the proposed method can reduce the number of switches and passive devices, which is beneficial to reduce the cost of drive system.

REFERENCES:

[1] R. Krishnan, Permanent magnet synchronous and brushless DC motor drives[M]. CRC Press/Taylor & Francis, 2010.

[2] S. Chen, X. Zhou, G. Bai, K. Wang, et al, “Adaptive commutation error compensation strategy based on a flux linkage function for sensorless brushless DC motor drives in a wide speed range,” IEEE Trans. Power Electron., vol. 33, no. 5, pp. 3752–3764, May. 2018.

[3] A. Lee, C. Fan, and G. Chen, “Current integral method for fine commutation tuning of sensorless brushless DC motor,” IEEE Trans. Power Electron., vol. 32, no.12, pp. 9249–9266, Dec. 2017.

[4] Y. Shen and Z. Q. Zhu, “Investigation of permanent magnet brushless machines having unequal-magnet height pole,” IEEE Trans. Magn., vol. 48, no. 12, pp. 4815–4830, Dec. 2012.

[5] W. Jiang, Y. Liao, J. Wang, and Y. Xie, “Improved control of BLDCM considering commutation torque ripple and commutation time in full speed range,” IEEE Trans. Power Electron., vol. 33, no.5, pp. 4249–4260, May. 2018.

A Novel V2V Charging Method Addressing the Last Mile Connectivity

 ABSTRACT

One of the main drawbacks in adopting EV vehicles is the last mile connectivity issue. There is always a chance that the user/rider may get stranded without EV charge and no EV charging stations nearby. With the aim of solving such an exigency, this paper proposes a novel V2V charging technique which allows charge transfer between two EVs off the grid, and discusses its modes of operation. Non-isolated bidirectional DC-DC converters with average current control technique are simulated in a MATLAB/Simulink environment to verify and validate the efficiency and charging time for the proposed charging technique.

KEYWORDS

1.      V2V charging

2.      Bi-directional converter

3.      Pricing strategy

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

A V2V charging scheme is proposed to synchronize the charging between two electric vehicles. This is particularly needed when an EV user is left stranded without battery charge and with no access to EV charging station. In this scenario, the proposed model allows another EV user to assist the stranded EV by charging from his EV thus solving last mile connectivity issues. The proposed model consists of a dual converter in the electric vehicle which enables fast DC charging or discharging. Extensive MATLAB simulation results on the model proves that the proposed work is capable of charging an EV from another under average current control method. The efficiency, SOC status and charging time for the proposed method is also analyzed. From the analysis it is evident that as the SOC difference increases the efficiency obtained also increases. To reduce the charging time and to enhance the efficiency average current control method is simulated and analyzed. The results obtained are presented and the results confirm the effectiveness of the proposed work. V2V energy transfers which were reported in the earlier literature uses the concept of connected ad-hoc networks present in parking lots etc., where the vehicles parked in the parking lot are used for energy transfer through a connected bus in the parking lot itself. The term ‘novel’ has been used here as the issue of EV being left stranded without battery charge and with no access to charging station is not addressed anywhere in the literature and also the technique of using cascaded bi-directional converters for charging one vehicle from the other vehicle adds novelty to the V2V energy transfer. Cascaded Bidirectional converters can even facilitate the charge transfer when the electric vehicles battery voltage levels are different, that’s why cascaded converters has been employed.

REFERENCES

[1] Markel, T., Saxena. S, Kahl. K, Pratt. R, "Multi-Lab EV Smart Grid Integration Requirements Study: Providing Guidance on Technology Development and Demonstration", National Renewable Energy Laboratory. Retrieved 2016-03-08, 2005.

[2] Liu, Wei-Shih, Jiann-Fuh Chen, Tsorng-Juu Liang, Ray-Lee Lin, and Ching-Hsiung Liu, “Analysis, design, and control of bidirectional cascaded configuration for a fuel cell hybrid power system," IEEE Transactions on Power Electronics 25,Vol. 6, 2010, pp no:- 1565-1575.

[3] Akshya, S., Anjali Ravindran, A. Sakthi Srinidhi, Subham Panda, and Anu G. Kumar, "Grid integration for electric vehicle and photovoltaic panel for a smart home." 2017 International Conference on Circuit, Power and Computing Technologies (ICCPCT), pp. 1-8, 2017.

[4] Nagar, Ishan, M. Rajesh, and P. V. Manitha, “A low cost energy usage recording and billing system for electric vehicle,” International Conference on Inventive Communication and Computational Technologies (ICICCT), pp. 382-384, 2017.

[5] Rajalakshmi, B., U. Soumya, and Anu G. Kumar. “Vehicle to grid bidirectional energy transfer: Grid synchronization using Hysteresis Current Control”, International Conference on Circuit, Power and Computing Technologies (ICCPCT), pp. 1-6, 2017.

Wind Energy Fed UPQC System for Power Quality Improvement

 ABSTRACT

The extensive use of non-linear loads in domestic, industrial and commercial services origin harmonic complications. Harmonics make malfunctions in profound equipment, voltage drop across the network, conductor heat increases and overvoltage through resonance. All these problems can be remunerated by using Unified Power Quality Controller (UPQC) and the operation of UPQC depends upon the available voltage across capacitor present in dc link. If the capacitor voltage is maintained constant then it gives satisfactory performance. The proposed research is basically on designing of Wind energy fed to the dc link capacitor of UPQC so as to maintain proper voltage across it and operate the UPQC for power quality analysis. The proposed technique is the grouping of shunt and series Active Power Filter (APF) to form UPQC which is fed wind energy system and connected to grid for better response in the output. In this paper, the simulation model of series APF, shunt APF, UPQC and Wind energy with UPQC are design in Matlab. The proposed Wind energy-UPQC is design in Matlab simulation for reduction of voltage sag, swell, harmonics in load current and compensation of active and reactive power.

KEYWORDS

1.      Harmonics

2.      Power quality

3.      Unified power quality conditioner

      Wind energy

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION

The advantage of wind energy system is to retain a constant voltage of 600 volts across the DC-Link capacitor. In this work the wind energy with boost converter output is 600V and simulation of wind energy-UPQC maintains constant voltage of 600V when Sag, Swell and Interruption occur. It also reduces the harmonics content to 2.33% if any nonlinear load is associated as shown in Figure 19. Hence the proposed scheme can regulate active and reactive power injection to the grid and compensate voltage sag and swell in addition to the other usual operation of UPQC effectible as the voltage across the dc link capacitor is maintained constant. Figure 20 shows DC link voltage.

REFERENCES

[1] Carrasco JM, Franquelo LG, Bialasiewicz JT, Galván E, PortilloGuisado RC, Prats MM, León JI, Moreno-Alfonso N. Power-electronic systems for the grid integration of renewable energy sources: A survey. IEEE Transactions on industrial electronics. 2006; 53(4): 1002-1016.

[2] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Wind Energy Integrated System Using Unified Power Quality Conditioner. International Journal of Power Electronics and Drive Systems (IJPEDS). 2017; 8(3): 1424.

[3] Samal S, Hota PK. Power Quality Improvement by Solar Photo-voltaic/Fuel Cell Integrated System Using Unified Power Quality Conditioner. International Journal of Renewable Energy Research (IJRER). 2017; 7(4): 2075-84.

[4] Samal S, Hota PK. Design and analysis of solar PV-fuel cell and wind energy based microgrid system for power quality improvement. Cogent Engineering. 2017; 4(1): 1402453.

[5] Basu M, Das SP, Dubey GK. Comparative evaluation of two models of UPQC for suitable interface to enhance power quality. Electric Power Systems Research. 2007; 77(7): 821-830.

 

Fuzzy Sliding Mode Control for Photovoltaic System

 ABSTRACT

In this study, a fuzzy sliding mode control (FSMC) based maximum power point tracking strategy has been applied for photovoltaic (PV) system. The key idea of the proposed technique is to combine the performances of the fuzzy logic and the sliding mode control in order to improve the generated power for a given set of climatic conditions. Different from traditional sliding mode control, the developed FSMC integrates two parts. The first part uses a fuzzy logic controller with two inputs and 25 rules as an equivalent controller while the second part is designed for an online adjusting of the switching controller’s gain using a fuzzy tuner with one input and one output. Simulation results showed the effectiveness of the proposed approach achieving maximum power point. The fuzzy sliding mode (FSM) controller takes less time to track the maximum power point, reduced the oscillation around the operating point and also removed the chattering phenomena that could lead to decrease the efficiency of the photovoltaic system.

KEYWORDS

1.      DC-DC converter

2.      Fuzzy sliding mode control

3.      photovoltaic system

4.      MPPT

5.      Solar energy

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION

In this paper, a fuzzy sliding mode controller based MPPT technique was developed and tested. The proposed controller is designed by combining the fuzzy logic and sliding mode control to guarantee the stability and the tracking performance and also to avoid the drawbacks of the traditional SM and FL controllers. A Matlab/Simulink based simulation of a stand-alone PV system under varying climatic conditions and two levels of load was carried out to validate the proposed controller. Simulation results demonstrate that the designed FSMC-MPPT exhibits good responses as it successfully and accurately achieved the maximum power point with a significantly higher performance than the P&O, SM and FLC strategies. The proposed approach provides a feasible approach to control PV power systems.

REFERENCES

[1] Dounis, A.I., Kofinas, P., Alafodimos, C., &Tseles, D. (2013). Adaptive fuzzy gain scheduling PID controller for maximum power point tracking of photovoltaic system. Renewable energy, 60, 202-214.

[2] Bhatnagar, P., & Nema, R.K. (2013). Maximum power point tracking control techniques: State-of-the-art in photovoltaic applications. Renewable and Sustainable Energy Reviews, 23, 224-241.

[3] Farhat, M., Barambones, O., & Sbita, L. (2015). Efficiency optimization of a DSP-based standalone PV system using a stable single input fuzzy logic controller. Renewable and Sustainable Energy Reviews, 49, 907-920.

[4] Kalashani, Mostafa Barzegar et Farsadi, Murtaza. New Structure for Photovoltaic Systems with Maximum Power Point Tracking Ability. International Journal of Power Electronics and Drive Systems, 2014, vol. 4, no 4, p. 489.

[5] Liu, F., Kang, Y., Zhang, Y., & Duan, S. (2008, June). Comparison of P&O and hill climbing MPPT methods for grid-connected PV converter. In Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference on (pp. 804-807). IEEE.