A Simple Voltage Modulator Scheme for Torque Ripple Minimization in a Permanent Magnet Brushless DC Motor

 ABSTRACT:

 This paper presents a simple dc-link voltage modulation scheme to minimize the commutation torque ripple in a Permanent Magnet Brushless DC Motor (PMBLDCM). Maintaining a constant current in the non-commutating (NC) phase helps to minimize the torque ripple, which can be achieved by boosting the motor input voltage whenever two phase currents are undergoing commutation. At low speeds, since the required ac voltage at commutation is also less than nominal, the standard PWM operation of inverter with the nominal dc-link voltage suffices. However, at higher speeds, a momentary (only during the commutation interval) boost in the dc-link voltage (above the nominal level) is needed to ensure boost in motor voltage, hence a steady current in the NC phase. In the proposed scheme, the dc voltage boost at higher speeds is obtained by connecting two capacitors in series which are normally connected in parallel across the dc-link. The proposed scheme is verified for a 1hp PMBLDCM drive through simulations and experiments in the laboratory. Results exhibit a notable improvement in reducing the torque ripple.

KEYWORDS:

 

1.      Dc-link voltage modulation

2.      Permanent magnet brushless dc motor

3.      Commutation torque ripple

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

A simple capacitor switching based dc-link voltage modulation scheme to minimize the commutation torque ripple in a PMBLDCM is presented in this paper. Maintaining a steady value of the NC phase current by altering the dc-link voltage can effectively minimize the torque ripple. PWM control of inverter at low speed range and PWM control along with dc-link voltage modulation at high speed range (proposed scheme) ensure a low torque ripple. A simple additional circuitry is employed to momentarily boost the dc voltage to the inverter in the high speed range. The DVM scheme offers a significant diminution in torque ripple and a smooth and noise free operation of the PMBLDC machine.

REFERENCES:

 

[1] R. Krishnan, “Electric Motor Drives Modeling, Analysis and Control”, PHI Learning Private Limited, 2001.

[2] P. Pillay and R. Krishnan, “Modeling, simulation, and analysis of permanent-magnet motor drives, Part II: The permanent magnet synchronous drive,” IEEE Trans. Ind. Appl., vol. IA-25, no. 2, pp.265–273, Mar./Apr. 1989.

[3] R. Carlson, L.-M. Milchel, and J. C. Fagundes, “Analysis of torque ripple due to phase commutation in brushless dc machines,” IEEE Trans. Ind.Appl., vol. 28, no. 3, pp. 632–638, May/Jun. 1992.

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

[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 Sensorless Commutation Error Correction Method for High-speed BLDC Motors Based on Phase Current Integration

ABSTRACT:

 Inaccurate commutation in brushless dc motor (BLDCM) will induce current harmonic and increase motor loss, which reduce motor efficiency. Meanwhile, for the sensorless BLDCM, the motor commutation is seriously affected by detection errors and calculation errors, which are caused by the nonideal conditions and the parameters variation. In this paper, a novel commutation error correction method is proposed to determine optimal commutation instant for the sensorless high-speed BLDCM. First, the relationship between commutation error and motor phase current is analyzed. According to this relationship, an initial commutation error can be calculated and compensated in one conduction interval. Then, on-line commutation corrections are  performed to compensate for the residual error in following conduction intervals. The correction accuracy of commutation instant is determined by the phase current integral difference. This method is insensitive to motor parameters and back electromotive force (BEMF) waveform. Therefore, the commutation error is effectively eliminated in the whole speed range. Finally, the feasibility and effectiveness of the proposed method are evaluated by experimental results.

KEYWORDS:

1.      Brushless dc motor

2.      High-speed

3.      Commutation error

4.      Phase current

5.      On-line optimizing

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

It is analyzed that the changes of phase voltage and phase current are caused by commutation error in BLDCM. Based on the above analysis and analytical expressions, a novel commutation error correction method is proposed. The proposed method has three characteristics as follow. 1) It decomposes the correction process into step-by-step compensation. Through the initial estimation of commutation error, the speed of correction is greatly improved for more accurate determining optimal commutation instant. The proposed method has good real-time performance without complicated parameters identification algorithms. 2) The rolling process is not sensitive for motor parameters and BEMF waveform. The variable width hysteresis controller implements an optimal control between correction accuracy and correction speed. From the experiment results, it can be shown that commutation error is effectively eliminated in the low-speed range and high-speed range. 3)  Besides, the current sensor exists in the motor speed-current control loop and it does not add new sensor. So the system reliability is improved and the cost is reduced

 

REFERENCES:

[1] T. Chun, Q. Tran, H. Lee, and H. Kim, “Sensorless control of BLDC motor drive for an automotive fuel pump using a hysteresis comparator,” IEEE Trans. Power Electron, vol. 29, no. 3, pp. 1382- 1391, Mar. 2014.

[2] Kai Liu , Ming Yin , Wei Hua , Ziqi Ma , Mingyao Lin , Yong Kong, “Design and Optimization of an External Rotor Ironless BLDCM Used in a Flywheel Energy Storage System,” IEEE Trans. Magnetics, vol.54, pp:2797 – 2801, Nov. 2018.

[3] Shaohua Chen, Gang Liu, Shiqiang Zheng, “Sensorless Control of BLDCM Drive for a High-Speed Maglev Blower Using Low Pass Filter,” IEEE Trans. Power Electron, vol. 32, no. 11, pp. 8845-8856, Nov. 2017.

[4] Christof Zwyssig, Simon D. Round, Johann W. Kolar, “An Ultrahigh- Speed, Low Power Electrical Drive System,” IEEE Trans. Industrial Electron, vol. 55, no. 2, Feb. 2008

[5] P. Alaeinovin, S. Chiniforoosh, and J. Jatskevich, “Evaluating misalignment of Hall sensors in brushless dc motors,” in Proc. IEEE Electron. Power Energy Conf. (EPEC), pp. 1–6, 2008.

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.