High-Stability Position-Sensorless Control Method for Brushless DC Motors at Low Speed

 ABSTRACT

In order to improve the stability of brushless DC (BLDC) motors at low speed, a high-stability position-sensorless control method is proposed in this paper. Because the back electromotive force (EMF) is very small at low speed, a novel algorithm is proposed to detect the zero crossing point (ZCP) of back EMF accurately. First, the line-to-line back EMF is computed based on the mathematical model of BLDC motors. Then, a low pass filter (LPF) with alterable cut-off frequency is used to reduce the disturbance of the line-to-line back EMF. Last, the commutation signal is obtained through. However, the commutation signal is delayed by the LPF. For this reason, based on the three-phase back EMF, a novel compensation algorithm including an open-loop and a close-loop is proposed to compensate commutation error. Moreover, the speed feedback has a big delay at low speed. According to this, a novel speed calculation algorithm is presented to decrease the delay. Both the simulation and experimental results validate the high stability and reliability of the proposed method.

KEYWORDS

1.      Brushless DC (BLDC) Motor

2.      Sensorless control

3.      Back electromotive force (EMF)

4.      Zero crossing point (ZCP)

5.      Commutation error

6.      High stability

7.      Low speed

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

This paper proposed a novel position-sensorless control method for BLDC motors at low speed. This method includes three new algorithms. (1) A novel ZCP detection algorithm which combined G function and a digital LPF with alterable cut-off frequency. (2) A new speed calculation algorithm. (3) A novel compensation algorithm. The simulation and experimental results show that the commutation error is less than 1.5% at around 1.7 ~ 17% of the rated speed. Therefore, the stability and reliability are verified.

REFERENCES

[1] Arashloo R S, Salehifar M, Romeral L, et al., “A robust predictive current controller for healthy and open-circuit faulty conditions of five-phase BLDC drives applicable for wind generators and electric vehicles.” Energy Convers. Magn., vol. 92, no. 2, pp. 437-447, 2015.

[2] Kim N H, Yang O, Kim M H, “BLDC motor control algorithm for industrial applications using a general purpose processor.” J. Power Electron., vol. 7, no. 2, pp. 132-139, 2007.

[3] Cheng K Y, Lin Y T, Tso C H, et al., “Design of a sensorless commutation IC for BLDC motors.” IEEE Power Electron Specialists Conf., vol. 18, no. 6, pp. 295-300, Nov. 2003.

[4] Zhang X Z, Wang Y N, “A novel position-sensorless control method for brushless DC motors.” Energy Convers. Magn., vol. 52, no. 3, pp. 1669-1676, 2011.

[5] Damodharan P, Vasudevan K, “Sensorless brushless DC motor drive based on the zero-crossing detection of back electromotive force (EMF) from the line voltage difference.” IEEE Trans. Energy Convers, vol. 25, no. 3, pp. 661-668, Sep. 2010.

Grid Interactive Solar PV Based Water Pumping Using BLDC Motor Drive

 ABSTRACT:

 This paper proposes a bidirectional power flow control of a grid interactive solar photovoltaic (PV) fed water pumping system. A brushless DC (BLDC) motor-drive without phase current sensors, is used to run a water pump. This system enables a consumer to operate the water pump at its full capacity for 24-hours regardless of the climatic condition and to feed a single phase utility grid when the water pumping is not required. The full utilization of a PV array and motor-pump is made possible in addition to an enhanced reliability of the pumping system. A single phase voltage source converter (VSC) with a unit vector template (UVT) generation technique accomplishes a bidirectional power flow control between the grid and the DC bus of voltage source inverter (VSI), which feeds a BLDC motor. The VSI is operated at fundamental frequency, which minimizes the switching loss. The maximum power point (MPP) operation of a PV array, and power quality improvements such as power factor correction and reduction of total harmonic distortion (THD) of grid are achieved in this system. Its applicability and reliability are demonstrated by various simulated results using MATLAB/Simulink platform and hardware implementation.

KEYWORDS:

1.      Power flow control

2.      Solar photovoltaic

3.      Brushless DC motor

4.      Voltage source converter

5.      Unit vector template

6.      Voltage source inverter

7.       Maximum power point

8.       Power quality

9.      Power factor

10.  Total harmonic distortion

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

REFERENCES:

[1] M. T. A. Khan, G. Norris, R. Chattopadhyay, I. Husain and S. Bhattacharya, “Autoinspection and Permitting With a PV Utility Interface (PUI) for Residential Plug-and-Play Solar Photovoltaic Unit,” IEEE Trans. Ind. Appl., vol. 53, no. 2, pp. 1337-1346, March-April 2017.

[2] M. Montorfano, D. Sbarbaro and L. Morán, “Economic and Technical Evaluation of Solar-Assisted Water Pump Stations for Mining Applications: A Case of Study,” IEEE Trans. Ind. Appl., vol. 52, no. 5, pp. 4454-4459, Sept.-Oct. 2016.

[3] Billel Talbi, Fateh Krim, Toufik Rekioua, Saad Mekhilef, Abdelbaset Laib and Abdesslam Belaout, “A high-performance control scheme for photovoltaic pumping system under sudden irradiance and load changes,” Solar Energy, vol. 159, pp. 353-368, 2018.

[4] Packiam Periasamy, N.K. Jain and I.P. Singh, “A review on development of photovoltaic water pumping system,” Renewable and Sustainable Energy Reviews, vol. 43, pp. 918-925, March 2015.

[5] R. Kumar and B. Singh, “BLDC Motor Driven Solar PV Array Fed Water Pumping System Employing Zeta Converter,” IEEE Trans. Ind. Appl., vol. 52, no. 3, pp. 2315-2322, May-June 2016.

 

Flux Observer Model for Sensorless Control of PM BLDC Motor with a Damper Cage

ABSTRACT: 

Sensorless control methods are commonly employed to derive the rotor position and speed information indirectly in permanent magnet (PM) brushless motor drives. Thereinto, the simple yet effective flux observer method is extensively applied in a wide range of applications. However, damper cage is sometimes employed in the rotor of certain PM brushless motor. Normally, high order current harmonic components occur in such damper cage during operations. The introduction of these extra current contents can significantly hinder the performance of conventional flux observer. By applying Park transformation, the fundamental harmonic components of stator phase currents, flux linkages, and voltages during steady-state operation, become constants under rotor synchronous reference frame, while the currents in the rotor damper cage are still alternating. In this paper, an improved flux observer method is proposed to filter the harmonic contents under the rotor synchronous reference frame for PM brushless motor with rotor damper cage. The validity and performance of the proposed flux observer are verified by both numerical analysis and experimental results.

KEYWORDS:

1.      Flux observer

2.      Mathematical model

3.      PM BLD motor

4.      Damper cage

5.       Harmonic components

 

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The harmonic components of the stator currents of the PM BLDC motor affect the accuracy of the flux observer-based sensorless control method. Moreover, some BLDC motors employ a damper cage or similar structure (such as the shield outside magnets, or the metal retaining sleeve) in the rotor. Since the currents in the damper cage cannot be measured, the flux observer-based sensorless control method is not readily applicable to such BLDC motors. Considering that the damper cage makes the stator currents have more harmonic components, an improved flux observer model is proposed. It is under the d-q synchronous rotating reference frame, so that all the fundamentals of voltage, current and flux linkage become DC components, whilst the harmonics of the stator currents and rotor cage currents are still AC components and can be easily eliminated with low pass filters. Using the left DC components (i.e., the fundamental components), the rotor position can be estimated accurately. According to the numerical analysis and experiment results, it is verified that 1the improved flux observer method works well for the BLDC motor with a damper cage, and the error between the observed and actual rotor position is sufficiently small.

REFERENCES:

 

[1] Apoorva Athavale, Kensuke Sasaki, Brent S. Gagas, Takashi Kato, Robert Lorenz, Variable Flux Permanent Magnet Synchronous Motor (VF-PMSM) Design Methodologies to Meet Electric Vehicle Traction Requirements with Reduced Losses, IEEE Trans. Ind. Appl., Vol. PP, No. 99, pp. 1-1, 2017.

[2] Ramakrishnan Raja, Tomy Sebastian, Mengqi Wang, Abraham Gebregergis, Mohammad Islam, Effect of Position Sensor Error on the Performance of Permanent Magnet Motor Drives, IEEE Trans. Ind. Appl., Vol. PP, No. 99, pp. 1-1, 2017.

[3] Peng Li, Wei Sun, Jian-Xin Shen, Flux Observer Model for Sensorless Control of PM BLDC Motor with a Damper Cage, Twelfth International Conference on Ecological Vehicles and Renewable Energies, 2017, Monte Carlo, Monaco:1-6.

[4] P. Snary, B. Bhangu, C. M. Bingham, ET AL., Matrix converters for sensorless control of PMSMs and other auxiliaries on deep-sea ROVs, IEE Proc., Electr. Power Appl., Vol. 152, No. 2, pp. 382–392, 2005.

[5] A. Kulkarni, M. Ehsani, A novel position sensor elimination technique for the interior permanent magnet synchronous motor drive, IEEE Trans. Ind. Appl., Vol. 28, No. 1, pp. 144–150, 199

Enhanced Generalized Vector Control Strategy for Torque Ripple Mitigation of IPM-type Brushless DC Motors

ABSTRACT:

 Optimal currents with appropriate harmonic components injected into the motor windings can effectively mitigate torque ripple for interior permanent magnet (IPM) type brushless DC motors (BLDCMs). However, existing approaches may fail to accurately inject the optimal currents into motors due to the limited current loop bandwidth. This paper proposes a simple enhanced generalized vector control strategy to mitigate the torque ripple for IPM-type BLDCMs. With the proposed vector control strategy, the control block diagram for IPM-type BLDCMs is as simple as that with traditional vector control for sinusoidal permanent magnet synchronous motors. Firstly, an electromechanical energy conversion voltage (EECV), considering the effects of the non-sinusoidal back-EMF and the rotor salience property, is proposed in -axis. Then, a novel coordinate frame is constructed with the proposed EECV, which is based on the arbitrary reference frame theory. As a result, the currents of IPM-type BLDCMs can be decomposed into two constant components, one being linked to the torque and the other one to the flux linkage. Thus, the bandwidth of current loop with simple proportional integral regulator can be equivalently expanded in the proposed coordinate frame. Finally, comprehensive experiments are conducted in different operation conditions to validate the effectiveness of the proposed vector control strategy. 1

KEYWORDS:

1.      Brushless DC motors (BLDCMs)

2.      Vector control

3.      Optimal currents

4.      Torque ripple mitigation

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

An enhanced generalized vector control strategy based on the arbitrary reference frame theory is proposed. And a voltage component involving in electromechanical energy conversion, namely EECV, is utilized to establish the novel coordinate frame of the generalized vector control strategy. Therefore, the current components of BLDCMs mapped in the proposed coordinate frame are constant, surmounting the bandwidth limitations of PI current regulator thoroughly. With the proposed strategy, the torque ripple minimization and MTPA operation for BLDCMs can be achieved simultaneously, and the steady and dynamic performance have been verified by experimental results. In addition, the influence of permanent magnet flux and inductance term variations on the torque ripple mitigation has been investigated with experimental tests.

In conclusion, the proposed method has the following advantages:

1) Compared with two phase feeding mode, the proposed method eliminates the switching of control strategy between normal conducting period and commutation period, and between low speed and high speedarea. Thus, the executability of torque ripple mitigation is enhanced.

2) Compared with the traditional vector control with Park transformation [4] and the vector control with GSRF [11], the proposed method can simplify the mathematical model of IPM-type BLDCMs, being similar with that of the surface sinusoidal PMSMs. Then, with simple PI current regulator, the steady state and transient state performance of torque ripple mitigation are improved.

3) Compared with the vector control based on the conventional rotor orientation with the additional resonant controllers[15]-[20]or repetitive controllers[21], or the method based on multiple reference frames[22], all torque ripple harmonic componentscan be mitigatedtheoretically, not only the selective torque harmonic components.Thus, the torque ripple can be mitigated further with the proposed method.

REFERENCES:

 

[1] T. Shi, X. Niu, W. Chen, and C. Xia, “Commutation torque ripple reduction of brushless DC motor in braking operation,”. IEEE Trans. Power Electron., vol.33 no.2, pp.1463-1475, Dec, 2018.

[2] H.S. Seol, J. Lim, D.W. Kang, J. S. Park and J. Lee, “Optimal design strategy for improved operation of IPM BLDC motors with low-resolution hall sensors,” IEEE Trans. Ind. Electro., vol.64, no.12, pp.9758-9766, Dec, 2017.

[3] M. Bertoluzzo, G. Buja, R. K. Keshri, and R. Menis, “Sinusoidal versus square-wave current supply of PM brushless DC drives: a conven-ience analysis,” IEEE Trans. Ind. Electro., vol.62, no.12, pp.7339-7349, Dec, 2015.

[4] G. Buja, M. Bertoluzzo, and R. K. Keshri, “Torque ripple-free operation of PM BLDC drives with petal-wave current supply,” IEEE Trans. Ind. Electro., vol.19, no.2, pp.4034-4043, July, 2015.

[5] J.-H. Song, and I. Choy, “Commutation torque reduction in brushless dc motor drives using a single dc current sensor,” IEEE Trans. Power Electron., vol.33 no.2, pp.312-319, Mar, 2004.

DC Environment for a Refrigerator With Variable Speed Compressor; Power Consumption Profile and Performance Comparison

 ABSTRACT:

 DC power distribution in residential sector has regained interest among researchers and industrial players as new electronics-based appliances became locally available. However, the compatibility of appliances with DC distribution systems still requires much research effort. This work mainly explores on the power consumption profile of an inverter-driven Variable Speed Controller (VSC-based) refrigerator that has not yet been analyzed as one of the most important household loads. This paper compares the power consumption in two scenarios; 1) using three supply configurations for a VSC-based refrigerator, a Battery-Inverter-Load, a Battery-Load and Grid-Load, and 2) using a same AC power source to supply a VSC-based refrigerator and a same-size conventional refrigerator. This analysis helps toward modeling and energy estimation of PV system applications involving storage batteries. A wireless monitoring circuit has been employed to handle temperature, current and voltage measurements with a high sampling rate to cover the potential surge power. The experimental measurements show a better performance on using DC over AC power source and the power rate consumed has a smooth pattern at the starting-on time until approach a rated power. The measured efficiency of the Battery-Load topology approaches 99% compared to that of the Battery-inverter-load topology, which is approximately 78.5%. It is also found that the tested refrigerator with Battery-Load topology consumes an energy amounting to 1.850 kWh daily, while with Battery-inverterload topology consumes 2.466 kWh daily under the same operating conditions. These results can serve as a model for modeling refrigerators and other appliances that adopt speed controller technology to drive their motors.

KEYWORDS:

1.      Compression refrigeration system

2.      Dc microgrid

3.      Total power consumption

4.      Building energy

5.      Modeling

6.      PV-battery systems

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, experimental tests have been conducted to evaluate the performance of a VSC-based refrigerator and the effectiveness of using such refrigerator with the proposed DC level of voltage towards the solar PV applications. Based on the obtained results, the followings can be concluded:

1) Since the power circuit of the new commerciallyavailable inverter-driven refrigerators is already rectifying an AC input, it is possible to efficiently use such refrigerators with the DC voltage level that equivalent to the rectified grid AC without any modification.

2) Using VSC-based refrigerators with the proposed (Battery-Load) has better performance than that with the traditional (Battery-Inverter-Load) configuration of PV systems, which increases system efficiency, prolongs system storage and decreases cost through dispensing the use of inverter.

3) As compared with the traditional, the power consumption pattern of the VSC-based refrigerator does not have any surge power, in which it is possible avoiding the using a very high capacity inverter and batteries even with the traditional configuration Battery- Inverter-Load.

4) The outcome of the conducted experiments for power consumption patterns can serve for further analysis such as; refrigerator consumption modeling, forecasting, and control purposes.

5) It is recommended to use a VSC-based refrigerator for systems that have battery pack within the solar PV scheme as the system would be more efficient and economical.

REFERENCES:

[1] M. J. Al-Dulaimi, F. A. Kareem, and F. A. Hamad, ``Evaluation of thermal performance for natural and forced draft wet cooling tower,'' J. Mech. Eng. Sci., vol. 13, no. 4, pp. 6007_6021, Dec. 2019, doi: 10.15282/jmes.13.4.2019.19.0475.

[2] O. Ekren, S. Celik, B. Noble, and R. Krauss, ``Performance evaluation of a variable speed DC compressor,'' Int. J. Refrig., vol. 36, no. 3, pp. 745_757, May 2013, doi: 10.1016/j.ijrefrig.2012.09.018.

[3] C. L. Xia, Permanent Magnet Brushless DC Motor Drives and Controls. Hoboken, NJ, USA: Wiley, Apr. 2012.

[4] Mathwork. Residential Refrigeration Unit_MATLAB & Simulink. Accessed: Mar. 29, 2020. [Online]. Available: https://www.mathworks. com/help/physmod/hydro/examples/residential-refrigeration-unit.html

[5] F. A. Qayyum, M. Naeem, A. S. Khwaja, A. Anpalagan, L. Guan, and B. Venkatesh, ``Appliance scheduling optimization in smart home networks,'' IEEE Access, vol. 3, pp. 2176_2190, 2015, doi: 10.1109/ACCESS.2015.2496117.

Comprehensive Controller Implementation for Wind-PV-Diesel Based Standalone Microgrid

 ABSTRACT:

  In this paper, a comprehensive controller of a standalone microgrid is implemented, which has three dispersed generation units based on a wind, solar photovoltaic array and a diesel generator. The power ratio variable step perturb and observe method is applied to achieve maximum power point tacking of a solar photovoltaic array and a variable speed wind turbine coupled a permanent magnet brushless DC generator without rotor/wind speed sensors. Moreover, to ensure perfect synchronization of a diesel generator to the point of common coupling (PCC), a control algorithm is developed, which is based on in-phase and quadrature units. An active power control based on proportional-integral controller with anti-windup, is used for voltage and frequency regulation. The LCL filter based on virtual resistor, is used for power quality improvement at PCC. Simulation and test results are presented for the validation of proposed system using a prototype of 2 kW in the laboratory.

KEYWORDS:

1.      Standalone microgrid

2.      Solar photovoltaic array

3.      Wind turbine

4.      Diesel generator

5.      Active damping

6.      LCL filter based virtual resistor

7.      PCC voltage regulation

8.      power quality improvement and PI controller with anti-windup

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The proposed microgrid for an isolated water treatment station based on three dispersed generation units; fixed speed DG, variable speed wind turbine and solar photovoltaic array, has been found to operate safely at sever conditions while supplying the load demand continuously at regulated voltage. The power ratio variable step P&O method for MPPT, has easily been implemented in a prototype to achieve high level of performance from wind turbine and solar photovoltaic array without any wind/speed sensors and without oscillations around MPP. The developed active power control based on AWPI controller with virtual resistor based active-damping for voltage regulation at PCC, has been implemented effectively and obtained results have demonstrated desired performance without saturation issue during transitions. The BES is protected from overcharging with utilization of excess power for space heating system as a DC dump load. DG has been used only as a backup energy source and its synchronization with PCC has been achieved safely without destabilizing the system operation. Switching harmonics are perfectly attenuated without losses using LCL filter based virtual resistor. Therefore, it is concluded that the comprehensive control proposed in this work for wind-solar diesel based standalone microgrid, is expected to be an effective alternative for uninterrupted supply in remote and isolated areas.

 REFERENCES:

[1] N. Mendis, K. M. Muttaqi, S. Perera, and M. N. Uddin, “Remote Area Power Supply System: An Integrated Control Approach Based on Active Power Balance,” IEEE Industry Applications Magazine, vol.21, no.2,pp.63-76, Mar. 2015.

[2] M. Rezkallah, S. Sharma, A. Chandra and B. Singh, “Implementation and control of small-scale hybrid standalone power generation system employing wind and solar energy,” in Proc. IEEE IAS Annual Meeting, 2016.

[3] Y. Tan, K. M. Muttaqi, P. Ciufo, and L. Meegahapola, “Enhanced Frequency Response Strategy for a PMSG-Based Wind Energy Conversion System Using Ultracapacitor in Remote Area Power Supply Systems,” IEEE Trans. Industry Applications., vol.53, no.1, pp. 549-558, Feb.2017.

[4] M. Rezkallah, A. Hamadi, A. Chandra, and B. Singh, “Hybrid AC-DC standalone system based on PV array and wind turbine,” in Proc. IECON, 2014, pp. 5533-5539.

[5] M. Rezkallah, A. Hamadi, A. Chandra, and B. Singh, “Real-Time HIL Implementation of Sliding Mode Control for Standalone System Based on PV Array Without Using Dumpload,” IEEE Trans. Sustainable Energy, vol. 6, no.4, pp. 1389-1398, Oct.2015.

 

Analysis of the Three-Phase Inverter Power Efficiency of a BLDC Motor Drive Using Conventional Six-Step and Inverted Pulsewidth Modulation Driving Schemes

ABSTRACT:

 In this paper, the three-phase inverter power efficiency of a brushless DC (BLDC) motor drive

is analyzed theoretically and verified experimentally. An inverted pulsewidth modulation driving scheme has higher power efficiency than a conventional six-step driving scheme, particularly under low rotor speed due to less diode conduction power loss of Sync metal–oxide–semiconductor field-effect transistors (MOSFETs). However, the difference in the power efficiency decreases as the rotor speed increases; for a rotor speed above 1000 r/min, the difference in the power efficiency is negligible. In addition, the power efficiency of the inverted driving scheme drops further than one for the conventional six-step driving scheme with sampling frequency increase. It is due to the additional switching power loss of Sync MOSFET. The theoretical analysis of power loss in a three-phase inverter verifies the experimental results.

KEYWORDS:

1.      Brushless dc (BLDC)

2.      Inverted pulsewidth modulation (PWM)

3.      Power efficiency

4.       Power loss

5.      Three-phase inverter

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, two different driving schemes for a BLDC motor drive, conventional six-step and inverted PWM, are analyzed in terms of power efficiency and loss to facilitate the understanding of the type and amount of the power loss in a three-phase inverter driving BLDC motor. Besides the conduction and switching power loss of HS and LS MOSFETs, the additional conduction and switching power loss from Sync MOSFET driven by an inverted PWM driving scheme must be compared to the conduction power loss from the diode of Sync MOSFET to select the more power-efficient driving scheme of the two schemes studied. The power efficiency of the three-phase inverter driven by the inverted PWM driving scheme is greater than that driven by the conventional six-step  driving scheme, particularly in the low rotor speed range. This is due to the reduction of the Sync MOSFET diode conduction power loss in the three-phase inverter driven by the inverted PWM driving scheme.

REFERENCES:

[1] J. Shao, D. Nolan, and T. Hopkins, “A novel direct back EMF detection for sensorless brushless DC (BLDC) motor drives,” in Proc. 17th Annu. IEEE Appl. Power Electron. Conf. Expo., Dallas, TX, USA, vol. 1, Mar. 2002, pp. 33–37.

[2] P. Yedamale, “Brushless DC (BLDC) motor fundamentals,” Microchip Technol. Inc., Chandler, AZ, USA, Appl. Note. 20:3-15, 2003.

[3] M. R. Rahman and P. Zhou, “Analysis of brushless permanent magnet synchronous motors,” IEEE Trans. Ind. Electron., vol. 43, no. 2, pp. 256–267, Apr. 1996.

[4] A. Hughes and W. Drury, Electric Motors and Drives: Fundamentals, Types and Applications. Oxford, U.K.: Newnes, 2013.

[5] J. S. Lawler, J. M. Bailey, J. W. McKeever, and J. Pinto, “Limitations of the conventional phase advance method for constant power operation of the brushless DC motor,” in Proc. IEEE Southeast Con, Apr. 2002, pp. 174–180.