Performance Enhancement of Evaporative Water Cooler Equipped with Permanent Magnet Brushless Motor Drive Based on Power Control Strategy

 ABSTRACT:

 Evaporative coolers with single-phase induction motors (SPIMs) are one of the least efficient and most commonly used electrical power consumers all over the world. Recently, it has been suggested to substitute SPIMs with higher-efficiency motors, such as permanent magnet brushless (PMBL) motors. However, control method for brushless motors often work based on speed, while laboratory tests indicate that, due to fluid characteristics of the blower, the airflow rate is not just related to the speed, where increasing the cooler’s duct length reduces the airflow rate, thereby preventing the desired airflow rate to be reached. To overcome this problem, in this work, a new power based control scheme has been developed to stabilize the outlet airflow rate instead of the speed control. In this approach, output power of PMBL motor is regulated around a set point power corresponding to the desired air flow rate. A 5000 m3/h evaporative cooler equipped with brushless motor was tested with both constant speed and power control strategies. Results indicated superiority of the proposed brushless motor drive and power control scheme.

KEYWORDS:

1.      Brushless motor

2.      Efficiency

3.      Electric drive

4.      Energy saving

5.      Evaporative cooler

6.      Power control

SOFTWARE:MATLAB/SIMULINK

 CONCLUSION:

In this paper, application of a brushless motor drive for a 5000 m3/h commercial evaporative cooler to replace a conventional SPIM has been investigated. Efficiency test results indicate an improved efficiency of at least 75% compared to SPIM. This would improve the energy ranking grade of the evaporative cooler system from IE1 to IE5. Challenges involved in airflow reduction due to various pressure differences caused by restrictions in ducting systems (length, bends, etc.) were discussed. A newly constant power control method was proposed to replace the conventional constant speed control method to overcome such challenges. Various approaches were expressed for determination of feedback power, required in the proposed power control method. For simplicity and cost efficiency, the input current of the drive, proportional to the feedback power was employed for this purpose. Air flow rate test results confirmed that the proposed method could maintain a desired flow at longer ducting systems or operating conditions yielding higher pressure differences. Further improvements may be achieved in increasing the system reliability and cost efficiency, using sensorless control methods or employing directly coupled brushless motor assembly.

REFERENCES:

[1]. F. Sojdei, M. Eslami, N. Sayfi, ―Potential of Energy Conservation in the Industry of Iran‖, ECEEE Industrial Summer Study Proceedings, pp. 323-330, 2014.

[2]. Fernando J. T. E. Ferreira, Aníbal T. de Almeida, ―Overview on Energy Saving Opportunities in Electric Motor Driven Systems – Part 1 System Efficiency Improvement‖, IEEE/IAS 52nd Industrial and Commercial Power Systems Technical Conference (I&CPS), pp. 1-8, 2016.

[3]. R.G.D. Caetano, M.G.S.R. Pontes, V. L.L. Costa, R.S.T. Pontes, ―Energy efficiency electric motor systems: Motor replacement analysis — A case study‖, Simposio Brasileiro de Sistemas Eletricos (SBSE), pp. 1-6, 2018.

[4]. K.S. Rathikrindi, S.Paramasivam, L. Sandeep, ―Energy saving opportunities through Variable Frequency Drive for Commercial Air Conditioners‖, 4th International Conference on Electrical Energy Systems (ICEES), pp. 338-340, 2018.

[5]. D. Pullaguram, S. Mishra, S, Banerjee, ―Standalone BLDC based solar air cooler with MPPT tracking for improved efficiency‖, IEEE 7th Power India International Conference (PIICON), pp. 1-5, 2016

 

Sensorless Start-Up Strategy for a 315 kW High-Speed Brushless DC Motor with Small Inductance and Non-ideal Back-EMF

 ABSTRACT:

 This paper presented a novel sensorless start-up strategy for a 315kW high-speed magnetic suspension brushless DC (BLDC) motor with small inductance and non-ideal back electromotive force (back-EMF). Two key strategies on the sensorless start-up strategy of BLDC motor were presented: (1) small current start-up strategy for the high-speed BLDC motor with small inductance, and (2) self-adaption control strategy to compensate the commutation error for the BLDC motor with non-ideal back-EMF in the start-up stage. A hybrid pulse width modulation (PWM) strategy based on the load torque was proposed to limit the start-up current. An optimal motor start-up curve based on the system parameters was presented, and a self-adaption control strategy was proposed to solve the synchronous switching problem. The effectiveness and feasibility of the proposed method were verified by a series of experiments on the 315 kW-20000 rpm magnetic suspension blower platform.

KEYWORDS:

1.      BLDC motor

2.      Small inductance

3.      Non-ideal back-EMF

4.      Sensorless

5.      Start-up strategy

6.      Self-adaption control strategy

SOFTWARE:MATLAB/SIMULINK

CONCLUSION:

This paper analyzed the main factors that influence the sensorless start-up performance of the high-power high-speed BLDC motor with small inductance and non-ideal back-EMF. A reliable start-up strategy was proposed by improving the detection of the initial rotor position, the closed-loop acceleration, and the synchronous switching process. The important conclusions were listed as follows.

(1) The rotor initial position can be positioned by the “two step” detection strategy. The start-up current can be adjusted according to the load torque in real time. Therefore, the method proposed in this paper ensured that the motor can start-up successfully under the load condition.

(2) The speed-up curve in the external-synchronization stage was optimized by analyzing the relationship between the motor speed and the terminal voltage. The rotor rotating time from the stationary position to a specify position was obtained by analyzing the average torque in 1/6 cycle and the rotor inherent characteristic.

(3) The synchronous switching process was improved by estimating the commutation error angle and the free decelerating. The influence of the back-EMF shape was analyzed by Eq. (28) and (29). The problems of high frequency noise and the rotor position error were solved by the free decelerating.

REFERENCES:

[1] A. Boglietti, C. Gerada, A. Cavagnino, “High-speed electrical machines and drives,” IEEE Trans. Ind. Electron., vol. 61, no. 6, pp. 2943-2945, Jun. 2014.

[2] W. Li, J. Fang, H. Li, J. Tang, “Position sensorless control without phase shifter for high–speed BLDC motors with low inductance and non-ideal back EMF,” IEEE Trans. Power Electron., vol. 31, no. 2, pp. 1354–1366, Feb. 2016.

[3] S. Chen, G. Liu, S. Zheng, “Sensorless control of BLDCM drive for a High-Speed maglev blower using a low pass filter,” IEEE Trans. Power Electron., vol. 32, no. 11, pp. 8845–8856, Nov. 2017.

[4] S. Shinnaka, “New “D-state-observer”-based vector control for sensorless drive of permanent-magnet synchronous motors,” IEEE Trans. Ind. Appl., vol. 41, no. 3, pp. 825–833, Jun. 2005.

[5] G. Liu, C. Cui, K. Wang, B. Han, S. Zheng, “Sensorless control for high–speed brushless DC motor based on the line–to–line back EMF,” IEEE Trans. Power Electron., vol. 31, no. 7, pp. 4669–4683, Jul. 2016.

 

Sensorless BLDC Motor Commutation Point Detection and Phase Deviation Correction Method

ABSTRACT:

 Phase-to-neutral voltage or neutral-to-virtual neutral voltage zero-crossing points (ZCPs) detection method is usually used for sensorless BLDC motor commutation control. Unfortunately, neither of them can be realized in lower speed range. In this paper, a simple commutation point detection method is proposed based on detecting inactive phase terminal to dc-link midpoint voltage. It eliminates the requirement of neutral wire or virtual neutral voltage and provides an amplified version of back electromotive force (EMF) at the ZCPs which makes the lower speed range detection possible. As the speed increasing, commutation point error is enlarged due to the low pass filter (LPF) et al. Utilizing the symmetry of the terminal to midpoint voltage the phase error can be corrected. However, due to the nonlinear relationship between the detected voltage difference and phase error, it is difficult to regulate the error fast and robustly. Therefore, a novel phase regulator based on fuzzy neural network (FNN) is proposed in this paper with simple structure and learning ability. The validity of the proposed ZCPs detection method and commutation instant shift correction method are verified through experimental results.

KEYWORDS:

 

1.      Brushless motor

2.      Efficiency

3.      Electric drive

4.      Energy saving

5.      Evaporative cooler

6.      Power control

SOFTWARE:MATLAB/SIMULINK

CONCLUSION:

In this paper, application of a brushless motor drive for a 5000 m3/h commercial evaporative cooler to replace a conventional SPIM has been investigated. Efficiency test results indicate an improved efficiency of at least 75% compared to SPIM. This would improve the energy ranking grade of the evaporative cooler system from IE1 to IE5. Challenges involved in airflow reduction due to various pressure differences caused by restrictions in ducting systems (length, bends, etc.) were discussed. A newly constant power control method was proposed to replace the conventional constant speed control method to overcome such challenges. Various approaches were expressed for determination of feedback power, required in the proposed power control method. For simplicity and cost efficiency, the input current of the drive, proportional to the feedback power was employed for this purpose. Air flow rate test results confirmed that the proposed method could maintain a desired flow at longer ducting systems or operating conditions yielding higher pressure differences. Further improvements may be achieved in increasing the system reliability and cost efficiency, using sensorless control methods or employing directly coupled brushless motor assembly.

REFERENCES:

[1]. F. Sojdei, M. Eslami, N. Sayfi, ―Potential of Energy Conservation in the Industry of Iran‖, ECEEE Industrial Summer Study Proceedings, pp. 323-330, 2014.

[2]. Fernando J. T. E. Ferreira, Aníbal T. de Almeida, ―Overview on Energy Saving Opportunities in Electric Motor Driven Systems – Part 1 System Efficiency Improvement‖, IEEE/IAS 52nd Industrial and Commercial Power Systems Technical Conference (I&CPS), pp. 1-8, 2016.

[3]. R.G.D. Caetano, M.G.S.R. Pontes, V. L.L. Costa, R.S.T. Pontes, ―Energy efficiency electric motor systems: Motor replacement analysis — A case study‖, Simposio Brasileiro de Sistemas Eletricos (SBSE), pp. 1-6, 2018.

[4]. K.S. Rathikrindi, S.Paramasivam, L. Sandeep, ―Energy saving opportunities through Variable Frequency Drive for Commercial Air Conditioners‖, 4th International Conference on Electrical Energy Systems (ICEES), pp. 338-340, 2018.

[5]. D. Pullaguram, S. Mishra, S, Banerjee, ―Standalone BLDC based solar air cooler with MPPT tracking for improved efficiency‖, IEEE 7th Power India International Conference (PIICON), pp. 1-5, 2016

 

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.