Front-End Buck Rectifier with Reduced Filter Size and Single-Loop Control

ABSTRACT:

This paper presents a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulse width modulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage. A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multi order decomposition. An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.

KEYWORDS:

1.      Buck rectifier (BR)

2.      Single-loop control

3.      Single phase

4.      Traction

5.      Transformerless

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a single-loop control scheme for single-phase BR has been presented. A nonlinear modulation scheme is proposed, and its effect is analyzed using a multi order system decomposition. The effectiveness of the proposed scheme is proved by simulation and experimental results. From experimental results, it is clear that the proposed control scheme is capable of maintaining sinusoidal source current and near-UPF operation with optimum filter volume, even under distorted grid conditions. Generalized design of the dc inductor, which is the most critical element, is presented in detail. Since source current wave shape is maintained despite ripples in dc current, requirement of an inner current loop is rendered superfluous. Apart from justifying the single-loop control scheme, this also entails greatly simplified controller design and realization.

REFERENCES:

[1] M. Brenna, F. Foiadelli, and D. Zaninelli, “New stability analysis for tuning PI controller of power converters in railway application,” IEEE Trans. Ind. Electron., vol. 58, no. 2, pp. 553–543, Feb. 2011.

[2] M. Carpita, M. Marchesoni, M. Pellerin, and D. Moser, “Multilevel converter for traction applications: Small-scale prototype test results,” IEEE Trans. Ind. Electron., vol. 55, no. 5, pp. 2203–2212, May 2008.

[3] P. Drabek, Z. Peroutka, M. Pitterman, and M. Cedl, “New configuration of traction converter with medium-frequency transformer using matrix converters,” IEEE Trans. Ind. Electron., vol. 58, no. 11, pp. 5041–5048, Nov. 2011.

[4] A. Rufer, N. Schibli, C. Chabert, and C. Zimmermann, “Configurable front-end converters for multicurrent locomotives operated on 16 2/3 Hz and 3 kV DC systems,” IEEE Trans. Power Electron., vol. 18, no. 5, pp. 1186–1193, Sep. 2003.

                                                                                                  

[5] S. Dieckerhoff, S. Bernet, and D. Krug, “Power loss-oriented evaluation of high voltage IGBTs and multilevel converters in transformerless traction applications,” IEEE Trans. Power Electron., vol. 20, no. 6, pp. 1328–1336, Nov. 2005

Initial Rotor Position Detection for Brushless DC Motors Based on Coupling Injection of High-Frequency Signal

ABSTRACT:

 In applications where motor inversion is forbidden, it is important to detect the initial rotor position of the motor. For this reason, based on coupling injection of high-frequency signal, a novel method of initial rotor position detection for brushless DC motors (BLDCM) is proposed in this paper. Firstly, the proposed method detects the relationship between three-phase winding inductances by injecting the high frequency detection signal into motor windings in a coupling way, and the initial rotor position is determined into two sectors with 180 degrees electric angle difference. Then, the polarity of the permanent magnet rotor is determined by applying two opposite voltage vectors to motor windings, so that the initial rotor position is determined into a unique sector, and the positioning accuracy is 30 degrees electric angle. The proposed method significantly reduces the amplitude of the detection signal while increases its frequency by the way of coupling injection, thus reducing the response current and electromagnetic torque generated by the high-frequency signal and reducing the possibility of rotor inversion. Finally, the effectiveness of the proposed method is verified by experimental results.

KEYWORDS:

1.      Brushless DC motor

2.      Initial rotor position

3.      High-frequency signal

4.      Coupling injection

SOFTWARE:MATLAB/SIMULINK

 CONCLUSION:

In this paper, the relationship between winding inductances and the rotor position of BLDCM is analyzed in detail, and a novel method of initial rotor position detection based on high-frequency signal coupling injection is proposed. The initial rotor position can be determined into a sector with 30 degrees electric angle. The proposed method overcomes the limitations of fixed DC-link voltage and limited switching frequency of the inverter by the way of coupling injection, and significantly reduces the amplitude of the detection signal while increases its frequency. Experimental results show that, compared with traditional methods, the method proposed in this paper can accurately detect the initial rotor position and effectively reduce the electromagnetic torque, thus reducing the possibility of rotor inversion in the process of initial position detection.

REFERENCES:

[1] K. Liu, Z. Zhou and W. Hua, “A Novel Region-Refinement Pulse Width Modulation Method for Torque Ripple Reduction of Brushless DC Motors,” IEEE Access, vol. 7, pp. 5333-5342, Dec. 2019, DOI. 10.1109/ACCESS.2018.2888630.

[2] C. L. Xia, G. K. Jiang, W. Chen and T. N. Shi, “Switching-Gain Adaptation Current Control for Brushless DC Motors,” IEEE Trans. Ind. Electron., vol. 63, no. 4, pp. 2044–2052, Apr. 2016, DOI. 10.1109/TIE.2015.2506144.

[3] 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, DOI. 10.1109/TIE.2012.2189536.

[4] B. Tan, X. Wang, D. Zhao, K. Shen, J. Zhao and X. Ding, “A Lag Angle Compensation Strategy of Phase Current for High-Speed BLDC Motors,” IEEE Access, vol. 7, pp. 9566-9574, Dec. 2019, DIO. 10.1109/ACCESS.2018.2887106.

[5] J. Shao, “An improved microcontroller-based sensorless brushless DC (BLDC) motor drive for automotive applications,” IEEE Trans. Ind. Appl., vol. 42, no. 5, pp. 1216–1221, Sep. 2006, DOI. 10.1109/TIA.2006.880888

A New Five-Level Buck-Boost Active Rectifier

 ABSTRACT:

 In this paper a new single-phase five-level buck boost active rectifier is introduced called capacitor tied switches (CTS). The proposed rectifier has two independent DC outputs that can be connected to two different loads. Different switching  states and the average mode of the proposed topology are analyzed to design the associated controller aims at regulating the two output DC voltages, generating five-level voltage at the input of the rectifier and finally draw unity power factor and sinusoidal current from AC grid. From AC grid view, the rectifier works in boost mode however the generated DC voltage can be split into two separate outputs which may be less than the AC peak voltage or even more leads to work in both buck and boost operation mode. Full simulation results are shown and analyzed to validate the effective operation and good dynamic performance of the proposed five-level buck-boost rectifier.

KEYWORDS:

1.      Multilevel converter

2.      Packed U-Cell

3.      Active PFC rectifier

4.      Buck-boost rectifier

5.      Capacitor Tied Switches (CTS).

SOFTWARE:MATLAB/SIMULINK

CONCLUSION:

In this paper a new topology of buck-boost active rectifier has been introduced based on slight modification of the third U-cell of the PUC original design. The proposed rectifier called CTS includes six switches tied by two capacitors as two output independent DC terminals and generates five-level voltage waveform at the input. The latter draw low harmonic current in-phase with the grid voltage making the operation at unity power factor rectifier easy in both buck and boost mode. This topology does not need additional bulky filters while switching at low frequency which constitute a big advantage of the presented CTS rectifier. Simulation results including regulated DC voltages, high power factor, and low supply THD current mainly obtained by the five-level rectifier input voltage. Moreover, good dynamic performance, fast response and reliable operation of the implemented controller and CTS converter topology were proven and discussed in details.

REFERENCES:

[1] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, "A review of single-phase improved power quality ACDC converters," Industrial Electronics, IEEE Transactions on, vol. 50, pp. 962-981, 2003.

[2] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, "A review of three-phase improved power quality AC-DC converters," Industrial Electronics, IEEE Transactions on, vol. 51, pp. 641-660, 2004.

[3] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[4] L. Yacoubi, K. Al-Haddad, L.-A. Dessaint, and F. Fnaiech, "Linear and nonlinear control techniques for a three-phase three-level NPC boost rectifier," Industrial Electronics, IEEE Transactions on, vol. 53, pp. 1908-1918, 2006.

[5] L. Yacoubi, K. Al-Haddad, L.-A. Dessaint, and F. Fnaiech, "A DSPbased implementation of a nonlinear model reference adaptive control for a three-phase three-level NPC boost rectifier prototype," Power Electronics, IEEE Transactions on, vol. 20, pp. 1084-1092, 2005.

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.