An Envelope Type (E-Type) Module Asymmetric Multilevel Inverters With Reduced Components

ABSTRACT:

This paper presents a new E-Type module for asymmetrical multilevel inverters with reduced components. Each module produces 13 levels with four unequal DC sources and 10 switches. The design of the proposed module makes some preferable features with a better quality than similar modules such as the low number of semiconductors and DC sources and low switching frequency. Also, this module is able to create a negative level without any additional circuit such as an H-bridge which causes reduction of voltage stress on switches. Cascade connection of the proposed structure leads to a modular topology with more levels and higher voltages. Selective harmonics elimination pulse width modulation (SHE-PWM) scheme is used to achieve high quality output voltage with lower harmonics. MATLAB simulations and practical results are presented to validate the proposed module good performance. Module output voltage satisfies harmonics standard (IEEE519) without any filter in output.

KEYWORDS:

1.      Asymmetric

2.      Components

3.      E-Type

4.      Multilevel inverter

5.      Power electronics

6.      Selective harmonics elimination

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Proposed E-Type module of multilevel inverter (a) Circuit topology

 EXPECTED SIMULATION RESULTS:

Fig.2 Output voltage and FFT analysis of proposed multilevel

CONCLUSION:

This paper presented a new multilevel inverter topology named as Envelope Type (E-Type) module which can generate 13 levels with reduced components. It can be used in high voltage high power applications with unequal DC sources. As E-Type module can be easily modularized, it can be used in cascade arrangements to form high voltage outputs with low stress on semiconductors and lowering the number of devices. Modular connection of these modules leads to achieve more voltage levels with different possible paths. It causes an improvement in the reliability of the modular inverter which enables it to use different paths in case of malfunction for a switch or a driver. The main advantage of proposed module is its ability to generate both positive and negative output voltage without any H-bridge circuit at the output of the inverter. THDv% is obtained 3.46% and 4.54% in simulation and experimental results, respectively that satisfy harmonics standard (IEEE519). Also module is tested in three frequency and under different resistive – inductive loads which results shows good performance.

REFERENCES:

[1] R. Feldman, M. Tomasini, E. Amankwah, J.C. Clare, P.W. Wheeler, D.R. Trainer, R.S. Whitehouse, "A Hybrid Modular Multilevel Voltage Source Converter for HVDC Power Transmission," IEEE Trans. Ind. Appl., vol.49, no.4, pp.1577–1588, July-Aug. 2013.

[2] M. Odavic, V. Biagini, M. Sumner, P. Zanchetta, M. Degano, "Low Carrier–Fundamental Frequency Ratio PWM for Multilevel Active Shunt Power Filters for Aerospace Applications," IEEE Trans. Ind. Appl., vol.49, no.1, pp.159–167, Jan.-Feb. 2013.

[3] Liming Liu, Hui Li, Seon-Hwan Hwang, Jang-Mok Kim, "An Energy-Efficient Motor Drive With Autonomous Power Regenerative Control System Based on Cascaded Multilevel Inverters and Segmented Energy Storage," IEEE Trans. Ind. Appl., vol.49, no.1, pp.178–188, Jan.-Feb. 2013.

[4] Yushan Liu, Baoming Ge, H. Abu-Rub, F.Z. Peng, "An Effective Control Method for Quasi-Z-Source Cascade Multilevel Inverter-Based Grid-Tie Single-Phase Photovoltaic Power System," IEEE Trans. Ind. Inform., vol.10, no.1, pp.399–407, Feb. 2014.

[5] Jun Mei, Bailu Xiao, Ke Shen, L.M. Tolbert, Jian Yong Zheng, "Modular Multilevel Inverter with New Modulation Method and Its Application to Photovoltaic Grid-Connected Generator," IEEE Trans. on Power Electron., vol.28, no.11, pp.5063–5073, Nov. 2013.

Unknown Input Observer for a Novel Sensorless Drive of Brushless DC Motors

 ABSTRACT:

In this paper, a novel motor control method is proposed to improve the performance of sensorless drive of BLDC motors. In the terminal voltage sensing method, which is a great portion of sensorless control, a precise rotor position cannot be obtained when excessive input is applied to the drive during synchronous operation mode. Especially in the transient state, the response characteristic decreases. To cope with this problem, the unknown input (back-EMF) is modelled as the additional state of system in this paper. Taking into account the disturbance adopted by the back-EMF, the observer can be obtained by an equation of the augmented system. An algorithm to detect the back-EMF of a BLDC motor using the state observer is constructed. As a result, a novel sensorless drive of BLDC motors that can strictly estimate rotor position and speed is proposed.

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Block diagram of BLDC motor drive.

EXPECTED SIMULATION RESULTS:

Fig. 2. Speed response for the start and transient state. (a) In the proposed sensorless scheme. (b) In the conventional scheme use sensor.

Fig. 3. Simulation results of the proposed sensorless scheme at 2000 (rpm). (a) Rotor speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF. (e) Commutation function. (f) Commutation signal.

Fig. 4. Simulation results of the proposed sensorless scheme at 100 (rpm). (a) Rotor speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF. (e) Commutation function. (f) Commutation signal.

CONCLUSION:

In this paper, the unknown input (back-EMF) is modeled as the additional state of system. Considering disturbance that is adopted by back-EMF, the observer can be obtained effectively using the equation of augmented system and estimating back-EMF. As a result, an effective algorithm to estimate rotor position and speed of motor using the state observer is proposed. Use of sensorless control method can remove problem on manufacture that is happened in circuit to detect rotor position and speed. Moreover the production of inexpensive motor controller may be possible because the additional circuit such as encoder is not necessity. In cases using the proposed sensorless control method, the start-up performance has an almost analogous transient state characteristic after forced alignment, compared with the conventional method. This method also provides useful motor control because it is possible to analyze about transient state as well as steady state unlike various sensorless control methods that have been recently proposed. In addition, it can be easily applied in industry applications requiring the low-cost style drive of BLDC motor because actual realization is very simple.

REFERENCES:

[l] T. J. E Miller, “Brushless Permanent-Magnet and Reluctance Motor Drives,” Clarendon Press, Oxford 1989.

[2] S. Ogasawara and H. Akagi, “An Approach to Position Sensorless Drive for Brushless DC Motors,” IEEE Trans. Ind. Appl., vol. 27, no. 5, pp. 928-933, Sep./Oct. 1991.

[3] 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. 1392-1401, Nov./Dec. 1996.

[4] H. R. Andersen and J. K. Pedersen, “Sensorless ELBERFELD Control of Brushless DC Motors for Energy-Optimized Variable-Speed Household Refrigerators,” EPE Conf. Rec., vol. 1, pp. 314-318, Sep. 1997.

[5] Hyeong-Gee Yee, Chang-Seok Hong, Ji-Yoon Yoo, Hyeon-Gil Jang, Yeong-Don Bae and Yoon-Seo Park, “Sensorless Drive for Interior Permanent Magnet Brushless DC Motors,” Electric Machines and Drives Conf. Record, 1997, IEEE International 18-21 pp. TD1/3.1-TD1/3.3, May 1997.

Sensorless Brushless DC Motor Drive Based on the Zero-Crossing Detection of Back Electromotive Force (EMF) From the Line Voltage Difference

 ABSTRACT:

This paper describes a position sensorless operation of permanent magnet brushless direct current (BLDC) motor. The position sensorless BLDC drive proposed, in this paper, is based on detection of back electromotive force (back EMF) zero crossing from the terminal voltages. The proposed method relies on a difference of line voltages measured at the terminals of the motor. It is shown, in the paper, that this difference of line voltages provides an amplified version of an appropriate back EMF at its zero crossings. The commutation signals are obtained without the motor neutral voltage. The effectiveness of the proposed method is demonstrated through simulation and experimental results.

KEYWORDS:

1.      Back electromotive force (EMF) detection

2.       Brushless dc (BLDC) motor

3.      Sensorless control

4.      Zero crossing

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the experimental setup.

EXPECTED SIMULATION RESULTS:

Fig. 2. Phase current and speed waveform on no-load (experimental).

Fig. 3. Phase current and speed waveform on load (experimental).

Fig. 4. Phase current and speed waveform during loading transient (experimental).

Fig. 5. Phase current, virtual Hall, and real Hall sensor signal for 50% duty

ratio PWM switching.

CONCLUSION:

A simple technique to detect back EMF zero crossings for a BLDC motor using the line voltages is proposed. It is shown that the method provides an amplified version of the back EMF. Only three motor terminal voltages need to be measured thus eliminating the need for motor neutral voltage. Running the machine in sensorless mode is then proposed, in this paper, making use of the novel zero-crossing detection algorithm. While starting relies on triggering devices at the zero crossings detected using the proposed algorithm, continuous running is achieved by realizing the correct commutation instants 30◦ delay from the zero crossings. The motor is found to start smoothly and run sensorless even with load and load transients. Simulation and experimental results are shown which validate the suitability of the proposed method.

REFERENCES:

[1] K. Iizuka,H.Uzuhashi, M. Kano, T. Endo, and K.Mohri, “Microcomputer control for sensorless brushless motor,” IEEE Trans. Ind. Appl., vol. IA- 21, no. 4, pp. 595–601, May/Jun. 1985.

[2] J. Shao, D. Nolan,M. Teissier, and D. Swanson, “A novel micro controller based sensorless brushless DC (BLDC) motor drive for automotive fuel pumps,” IEEE Trans. Ind. Appl., vol. 39, no. 6, pp. 1734–1740, Nov./Dec. 2003.

[3] T.-H. Kim and M. Ehsani, “Sensorless control of BLDC motors from near-zero to high speeds,” IEEE Trans. Power Electron., vol. 19, no. 6, pp. 1635–1645, Nov. 2004.

[4] S. Ogasawara and H. Akagi, “An approach to position sensorless drive for brushless DC motors,” IEEE Trans. Ind. Appl., vol. 27, no. 5, pp. 928–933, Sep./Oct. 1991.

[5] R. C. Becerra, T. M. Jahns, and M. Ehsani, “Four-quadrant sensorless brushless ECM drive,” in Proc. IEEE APEC, Mar. 1991, pp. 202–209.

Analysis Of Solar Energy Embeded To Distribution Grid For Active & Reactive Power Supply To Grid

ABSTRACT:

This paper presents a system of grid connected photovoltaic (PV) to the monitoring point of maximum power (MPPT). The voltage source inverter (VSI) is connected between the dc output of photovoltaic system and ac grid. The control strategy applied is based on theory of instantaneous reactive power (p-q theory). According to this proposed PV system send active power to the grid at the same time the reactive power of load and harmonics will eliminate at change in both irradiation and load condition. During no sunlight system is available only reactive power and harmonic compensation. The applicability of our system tested in simulation in Matlab / Simulink.

KEYWORDS:

1.      Grid-connected PV system

2.      Instantaneous reactive power theory

3.      MPPT

4.      Reactive power compensation

5.      Power quality

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed Grid Connected PV System

EXPECTED SIMULATION RESULTS:

Fig. 2. Active Power of load, PV system and grid

Fig. 3. Reactive Power of load, PV system and grid

Fig. 4. Current of Load, PV Inverter and Grid

                  

Fig. 5. Harmonic analysis with and without PV system

Fig. 6 Waveform of Grid Volatge and Current

CONCLUSION:

Photovoltaic power seems to be the favorable clean energy source of the future. So, to optimize its use we have proposed a direct coupling of PV system to the grid. From the results obtained, it is proven that by using the proposed system, Photovoltaic power can be efficiently extracted by solar cells and injected into the grid and compensating reactive power of the load all 24 h of the day. The proposed system also compensates the harmonics content of nonlinear load. Finally, and according to the obtained results we can consider the proposed system to be efficient solution to the growing demand of power at the present and in the future.

REFERENCES:

[1] Pandiarajan N, Ramaprabha R and RanganathMuthu. “Application of Circuit Model for Photovoltaic Energy Conversion System” INTERNATIONAL CONFERENCE’2010.

[2] Marcelo GradellaVillalva, Jonas Rafael Gazoli, Ernesto RuppertFilho, “Modeling And Circuit-based Simulation of Photovoltaic Arrays” 10^TH Brazilian Power Electronics Conference (COBEP), pp.1244-1254, 2009.

[3] SoerenBaekhoejKjaer, John K. Pedersen FredeBlaabjerg “A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules” IEEE Transactions On Industry Applications, 41(5), pp.1292-1306, 2005.

[4] FredeBlaabjerg, ZheChen,SoerenBaekhoejKjaer, “Power Electronics as Efficient Interface in Dispersed Power Generation Systems” IEEE Transactions On Power Electronics, 19(5)1184-1194, 2004.

[5] D. Picault, B. Raison, and S. Bacha “Guidelines for evaluating grid connected PV system topologies”. IEEE International Conference on Industrial Technology1-5, 2009.

Reduction of Commutation Torque Ripple in a Brushless DC Motor Drive

ABSTRACT :

This paper describes the reduction in torque ripple due to phase commutation of brushless dc motors. With two-phase 120⁰ electrical conduction for the inverter connected to the conventional three-phase BLDC machine, the commutation torque ripple occurs at every 60 electrical degrees when a change over from one phase to another occurs. This effect increases the commutation time at higher speeds which increases the torque ripple. The torque ripple is reduced by changing the switching mode from 120⁰ to a dual switching mode with 120⁰ switching at lower speeds and 180⁰ electrical for the inverter at higher speeds.

KEYWORDS:

1.      Brushless dc motor

2.      Current commutation

3.      Torque ripple

4.      Electric vehicle

     SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. PWM inverter and equivalent circuit of BLDC motor

EXPECTED SIMULATION RESULTS:

Fig.2. (a) Relative torque ripple amplitude and (b) The duration of

commutation time

CONCLUSION:

This paper has presented an analytical study of torque ripple comparison due to commutation of phase currents in a brushless dc motor for both 1200 and 1800 conduction modes. The results have been validated by simulation and experimental verification. In three-phase switching mode at high speeds the torque ripple and losses are minimized and therefore the efficiency of the machine is increased. But the same cannot be achieved at low speed in this mode. On the other hand, the 1200 situation is exactly opposite. Thus a composite switching scheme is proposed for satisfactory operation of the machine at all speeds. The effectiveness of the method is validated by suitable experiments.

REFERENCES:

[1] T. Li, and G. Slemon, “Reduction of cogging torque in permanent magnet motors,” IEEE Trans. on Magnetics, vol.24, no.6, pp.2901-2903, Nov. 1988.

[2] R. Carlson, M. Lajoie-Mazenc, and J.C.D.S. 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.

[3] H. Tan, “Controllability analysis of torque ripple due to phase commutation in brushless DC motors,” in Proc. 5th int. conf. Elect. Mach. And Syst., Aug. 18-20, 2001, vol.2, pp. 1317-1322.

[4] Y. Murai, Y. Kawase, K. Ohashi, K. Nagatake and K. Okuyama, “Torque ripple improvement for brushless DC miniature motors,” IEEE Trans. Ind. Appl., vol.25, no.3, pp. 441-450, May/Jun. 1989.

[5] C.S. Berendsen, G. Champenois, and A. Bolopion, “Commutation strategies for brushless DC motors: Influence on instant torque,” IEEE Trans. Power Electron., vol.8, no.2, pp. 231-236, Apr.1993.

Reducing Torque Ripple of Brushless DC Motor by Varying Input Voltage

ABSTRACT

This paper presents the method of reducing torque ripple of brushless direct current (BLDC) motor. In the BLDC motor, the torque ripple is decided by the back-electromotive force (EMF) and current waveform. If the back-EMF is constant in the conduction region of current, the torque ripple depends on the current ripple. The period of freewheeling region in the conduction region can be acquired by circuit analysis using the Laplace transformation and the torque ripple can be also reduced by varying input voltage to reduce the current ripple. The suggested method to reduce the torque ripple is confirmed by the dynamic simulation with the parameters of 500W BLDC motor.

KEYWORDS

1.      BLDC motor

2.      Current ripple

3.      Torque ripple

4.      Varying input voltage

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. PWM inverter and equivalent circuit of BLDC motor

EXPECTED SIMULATION RESULTS

Fig. 2. Back-EMF of 500 W BLDC motor at 6660 rpm.

Fig. 3. Current waveform of 500 W BLDC motor at 6660 rpm. (a) Experimental data. (b) Simulation data.

Fig. 4. Current and torque waveform in simulation. (a) Constant input voltage.

(b) Various input voltage..

CONCLUSION

This paper presents the method of reducing torque ripple of the BLDC motor by varying the input voltage after circuit analysis using the Laplace transformation. In the simulation confirmed by experiment, the torque ripple is reduced to 10%. The 500WBLDC motor used for simulation and experiment dose not have a trapezoidal back-EMF waveform but a sinusoidal back-EMF waveform. So the torque ripple is not reduced conspicuously, although the current ripple is reduced conspicuously, and produced torque ripple waveform is similar to the back-EMF waveform of 500 W BLDC motor.

REFERENCES

[1] J.-G. Lee, C.-S. Park, J.-J. Lee, G. H. Lee, H.-I. Cho, and J.-P. Hong, “Characteristic analysis of brushless motor condering drive type,” KIEE, pp. 589–591, Jul. 2002.

[2] T.-H. Kim and M. Ehsani, “Sensorless control of the BLDC motor from near-zero to high speeds,” IEEE Power Electron., vol. 19, no. 5, pp. 1635–1645, Nov. 2004.

[3] J. R. Hendershot Jr. and T. Miller, “Design of brushless permanent magnet motor,” in Oxford Magna Physics, 1st ed., 1994.

[4] P. Pillay and R. Krishnan, “Modeling, simulation, and analysis a permanent magnet brushless dc motor drive,” in Conf. Rec. 1987 IEEE IAS Annu. Meeting, San Diego, CA, Oct. 1–5, 1989, pp. 7–14.

[5] R. Carlson, M. Lajoie-Mazenc, and J. C. dos Fagundes, “Analsys of torque ripple due to phase commutation in brushless dc machines,” IEEE Trans. Ind. Appl., vol. 28, no. 3, pp. 632–638.