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 30delay 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” 10TH 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.

Model and system simulation of Brushless DC motor based on SVPWM control

 

ABSTRACT:

According to the disadvantages as large torque ripple of square wave drive brushless DC motor control system, this paper adopted the sine wave drive the permanent magnet brushless DC motor control system based on the space vector pulse width modulation (SVPWM) control method. The simulation model of space vector pulse width modulation control method of the rotated speed of brushless DC motor and current double closed-loop control system is simulated and analyzed in MATLAB/SIMULINK. The simulation results have verified the reasonability and validity of the simulation model.

KEYWORDS:

  1. Brushless DC motor
  2. Modeling and simulation
  3. Space vector pulse width modulation (SVPWM)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1 The overall system block diagram of BLDCM control system

EXPECTED SIMULATION RESULTS:

 

 

Figure 2 Speed information

Figure 3 Torque waveform

 

Figure 4 The motor stator three-phase current waveform

Figure 5 Phase A current use PWM and SVPWM control

 

CONCLUSION:

In this paper, the SVPWM control of BLDCM simulation model is established based on the MATLAB/SIMULINK, and used the classic speed, current double closed-loop PI control algorithm. From the output waveform, it can be seen the system corresponding speed fast, quickly achieve steady state. Plus load torque at t=0.1s, the speed happen fell but return to equilibrium state at soon. Three phase stator current waveform as nearly as sine wave. The simulation results show that the SVPWM control of BLDCM has good static and dynamic characteristics.

REFERENCES:

[1]Wu Quan-li, Huang Hong-quan. Simulation study of penmanent maagnet brushless DC motor based on PWM control. Electrical switches, Vol.5 (2010), p. 39-41

[2]Ma Ruiqing, Deng Junjun. Research on characteristic of sinusoidal current driving method for

BLDCM with hall position sensor. Micro-motor, Vol.7 (2011), p. 59-61

[3]Wang Shuhong. A control strategy of PMDC brushless motor based on SVPWM. Automation

Expo, Vol.10 (2008), p. 66-68

[4]Qiu Jianqi. SVPWM control for torque ripple attenuation of PM brushless DC motors. Small and medium-sized motor. Vol.2 (2003), p. 27-28

[5]Boyang Hu.180-Degree Commutation System of Permanent Magnet Brushless DC Motor Drive Based on Speed and Current Control.2009 Sencond International Conference on Intelligent Computation Technology and Automation,Vol.2 (2009), p. 723-726

Hybrid converter topology for reducing torque ripple of BLDC motor

 

 ABSTRACT

This study investigates the torque ripple performance of brushless DC (BLDC) motor drive system by integrating both modified single-ended primary inductor converter (SEPIC) and silicon carbide metal–oxide–semiconductor field-effect transistor based three-level neutral-point-clamped (NPC) inverter. In BLDC motor, the high commutation torque ripple is an important origin of vibration, speed ripple and prevents the use of the BLDC motor drive system in high-performance and high-precision applications. For torque ripple reduction, the modified SEPIC converter is employed at the entrance of the three-level NPC inverter, which regulates the DC-link voltage according to the motor speed. Moreover, the three-level NPC inverter is employed as a second-stage converter to suppress current ripple for further torque ripple reduction. Finally, the performance of the proposed hybrid converter topology is verified by simulation and laboratory experimental results.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

(a) Proposed converter topology

EXPECTED SIMULATION RESULTS

Fig. 2 Phase current and torque waveforms

(a) Phase current and torque waveforms from simulation at 2500 rpm and 0.825 N m, (b) Phase current and torque waveforms from simulation at 2500 rpm and 0.825 N m, (c) Phase current and torque waveforms from simulation at 6000 rpm and 0.825 N m, (d) Phase current and torque waveforms from simulation at 6000 rpm and 0.825 N m

CONCLUSION

A novel hybrid circuit topology has been proposed in this paperwhich is built by a modified SEPIC converter and a SiC-MOSFETbasedthree-level NPC converter for minimising torque ripple in aBLDC motor drive system. For efficient reduction of torque ripple,the first stage is the modified SEPIC converter that lifts the DClinkvoltage to the desired value based on the motor speedmeasurement. For further torque ripple reduction, the three-levelNPC inverter is employed as the second-stage converter tosuppress current ripple. Experimental results show that theproposed hybrid converter topology can suppress the torque rippleto 14.6% at the speed of 6000 rpm, commutation torque ripple isreduced substantially and produce smooth torque waveform thanthe BLDC motor driven by the two-level, three-level NPC, twolevelinverter with DC-link voltage control, and two-level inverterwith SEPIC converter and switch selection circuit topologies.

REFERENCES

[1] Singh, B., Bist, V.: ‘An improved power quality bridgeless Cuk converter fedBLDC motor drive for air conditioning system’, IET Power Electron., 2013,6, (5), pp. 902–913

[2] Carlson, R., Lajoie-Mazenc, M., Fagundes, J.C.D.S.: ‘Analysis of torqueripple due to phase commutation in brushless dc machines’, IEEE Trans. Ind.Appl., 1992, 28, (3), pp. 632–638

[3] Lee, S.K., Kang, G.H., Hur, J., et al.: ‘Stator and rotor shape designs ofinterior permanent magnet type brushless DC motor for reducing torquefluctuation’, IEEE Trans. Magn., 2012, 48, pp. 4662–4665

[4] Seo, U.J., Chun, Y.D., Choi, J.H., et al.: ‘A technique of torque ripplereduction in interior permanent magnet synchronous motor’, IEEE Trans.Magn., 2011, 47, (10), pp. 3240–3243

[5] Murai, Y., Kawase, K., Ohashi, K., et al.: ‘Torque ripple improvement forbrushless DC miniature motors’, IEEE Trans. Ind. Appl., 1989, 25, (3), pp.441–450

High-performance multilevel inverter drive of brushless DC Motor

ABSTRACT:

The brushless DC (BLDC) motor has numerous applications in high-power systems; it is simple in construction, is cheap, requires less maintenance, has higher efficiency, and has high power in the output unit. The BLDC motor is driven by an inverter. This paper presents design and simulation for a three-phase three-level inverter to drive the BLDC motor. The multilevel inverter is driven by discrete three-phase pulse width modulation (DPWM) generator that forced-commuted the IGBT’s three-level converters using three bridges to vectored outputs 12- pulses with three levels. Using DPWM with a three-level inverter solves the problem of harmonic distortions and low electromagnetic interference. This topology can attract attention in high-power and high-performance voltage applications. It provides a three-phase voltage source with amplitude, phase, and frequency that are controllable. The proposed model is used with the PID controller to follow the reference speed signal designed by variable steps. The system design is simulated by using Matlab/Simulink. Satisfactory results and high performance of the control with steady state and transient response are obtained. The results of the proposed model are compared with the variable DC-link control. The results of the proposed model are more stable and reliable.

KEYWORDS:

  1. Brushless DC Motor
  2. Multilevel Inverter
  3. High-Performance Drive
  4. Pulse Width Modulation (PWM)
  5. Maltlab
  6. Simulink

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Figure 1. BLDC motor with MLI driven with PID controller.

EXPECTED SIMULATION RESULTS:

 

 Figure. 2. Output of three-phase three-level inverter with DPWM.

Figure 3. The sample from output of the DPWM

Figure 4. Analysis of response for the proposed MLI with PID controller of BLDC motor.

Fig. 5. Two outputs of controllers with proposed MLI and variable DC-link

CONCLUSION:

The proposed MLI performance analysis was successfully presented by using Matlab/Simulink software. The proposed topology can be easily extended to a higher-level inverter. The simulation results were sine waves and exhibited fewer ripples and low losses. This system would show its feasibility in practice. The vector control was described in adequate detail and was implemented with a three-level MLI. This method enabled the operation of the drive at zero direct axis stator current. Transient results were obtained when a DPWM was started from a standstill to a required speed. The performance of the vector control in achieving a fast reversal of PDPWM even at very high speed ranges is quite satisfactory. The performance of the proposed three-phase MLI was investigated and was found to be quite satisfactory. A comparison was made between the PID controller–based proposed model MLI and the controller with variable DC-link voltage. The results showed that the proposed model responded better in transient and steady states and was more reliability with high performance.

REFERENCES:

[1] P. D. Kiran, M. Ramachandra, “Two-Level and Five-Level Inverter Fed BLDC Motor Drives”, International Journal of Electrical and Electronics Engineering Research, Vol. 3, Issue 3, pp 71-82, Aug 2013

[2] N. Karthika, A. Sangari, R. Umamaheswari , “Performance Analysis of Multi Level Inverter with DC Link Switches for Renewable Energy Resources”, International Journal of Innovative Technology and Exploring Engineering, Volume-2, Issue-6, pp 171-176, May 2013

[3] A. Jalilvand R. Noroozian M. Darabian, “Modeling and Control Of Multi-Level Inverter for Three-Phase Grid-Connected Photovoltaic Sources”, International Journal on Technical and Physical Problems of Engineering, Iss. 15, Vol. 5, No.2, pp 35-43, June 2013

[4] P. Karuppanan, K. Mahapatra, “PI, PID and Fuzzy Logic Controlled Cascaded Voltage Source Inverter Based Active Filter For Power Line Conditioners”, Wseas Transactions On Power Systems, Issue 4, Volume 6, pp 100-109, October 2011

[5] D. Balakrishnan, D. Shanmugam, K.Indiradevi, “Modified Multilevel Inverter Topology for Grid Connected PV Systems”, American Journal of Engineering Research, Vol. 02, Iss.10, pp-378-384, 2013

 

Compensation of torque ripple in high performance BLDC motor drives

 

ABSTRACT:

Brushless DC motor drives (BLDC) are finding expanded use in high performance applications where torque smoothness is essential. The nature of the square-wave current excitation waveforms in BLDC motor drives permits some important system simplifications compared to sinusoidal permanent magnet AC (PMAC) machines. However, it is the simplicity of the BLDC motor drive that is responsible for causing an additional source of ripple torque commonly known as commutation torque to develop. In this paper, a compensation technique for reducing the commutation torque ripple is proposed. With the experimental results, the proposed method demonstrates the effectiveness for a control system using the BLDC motors that requires high speed and accuracy.

KEYWORDS:

  1. Brushless DC motor drives
  2. Commutation
  3. Torque ripple
  4. Trapezoidal back EMF

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. The block diagram of the speed controller.

EXPECTED SIMULATION RESULTS:

Fig. 2. Experimental result in low-speed range (without compensation).

Fig. 3. Experimental result in low-speed range (with compensation).

Fig. 4. Experimental result in the high-speed range (without compensation).

Fig. 5. Experimental result in the high-speed range (with compensation).

Fig. 6. Experimental result in the high-speed range (with compensation).

Fig. 7. Sine wave response for the proposed speed controller.

CONCLUSION:

This paper has proposed a compensation technique for reducing the commutation torque ripple in high-performance BLDC motor drives. The idea is to equalize the mismatched times of two commutated phase currents during the commutation intervals. In low-speed operation, a method to slow down the rising time of the on-going phase current can be a desirable technique. In high-speed operation, a method to slow down the falling time of the off-going phase current becomes a desirable strategy. However, it is not easy to implement the proposed strategies by using cost-effective one-chip microprocessors because it is needed to calculate the commutation time intervals within the sampling period in low and high speed operation. Instead of calculating the commutation time intervals, two dimensional lookup tables that describe the relation of the commutation time interval and the motor parameters such as the back EMF and the initial motor current, are used. For the experiments, a 16-bit microprocessor was used for the controller. Additionally a CPLD (1600 gates) was used to generate gate signals of the inverter and the commutation time signals. To verify the feasibility of the propose method, it is applied to the spindle motor drive control for the industrial sewing machines. The effects of torque ripple are particularly undesirable in the industrial sewing machines. They lead to speed oscillations which cause deterioration in the performance. In addition, the torque ripple may excite resonances in the mechanical portion of the drive system, produce acoustic noise. With the experimental results, the proposed method demonstrates the effectiveness for a high-performance control system using the BLDC motors that requires high speed and accuracy.

REFERENCES:

 

Berendesen, C., Champenois, G., & Bolopion, A. (1993). Commutation strategies for brushless DC motor: influence on instant torque. IEEE Transactions on Power Electronics, 8(2), 231–236. Carlson, R., Lajoie-Mazenc, M., & Fagundes, J. C. S. (1992). Analysis of torque ripple due to phase commutation in brushless DC machines. IEEE Transactions on Industry Applications, 28(3), 632–638.

Chung, K., Zhu, Y., Lee, I., Lee, K., & Cho, Y. (2007). Simulation of the reduction of force ripples of the permanent magnet linear synchronous motor. Journal of E. E. T, 2(2), 208–215. Holtz, J., & Springob, L. (1996). Identification and compensation of torque ripple in high-precision permanent magnet motor drives. IEEE Transactions on Industrial Electronics, 43(2), 309–320.

Jahns, T. M., & Soong, W. L. (1996). Pulsating torque minimization techniques for permanent magnet AC motor drives—a review. IEEE Transactions on Industrial Electronics, 43(2), 321–330.

Commutation Torque Ripple Reduction in Brushless DC Motor Drives Using a Single DC Current Sensor

 

ABSTRACT:

This paper presents a comprehensive study on reducing commutation torque ripples generated in brushless dc motor drives with only a single dc-link current sensor provided. In such drives, commutation torque ripple suppression techniques that are practically effective in low speed as well as high speed regions are scarcely found. The commutation compensation technique proposed here is based on a strategy that the current slopes of the incoming and the outgoing phases during the commutation interval can be equalized by a proper duty-ratio control. Being directly linked with deadbeat current control scheme, the proposed control method accomplishes suppression of the spikes and dips superimposed on the current and torque responses during the commutation intervals of the inverter. Effectiveness of the proposed control method is verified through simulations and experiments.

KEYWORDS:

  1. Brushless dc motor drives
  2. Commutation torque ripple reduction
  3. Single dc current sensor

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Basic configuration of trapezoidal brushless dc motor drives with dc link current controlled.

EXPECTED SIMULATION RESULTS:

 

(a)

(b)

(c)

Fig. 2. Simulation results in the low speed range: (a) phase currents, (b) dc-link current, and (c) commutation torque ripple.

(a)

(b)

(c)

Fig. 3. Simulation results in the high speed range: (a) phase currents, (b) dc-link current, and (c) commutation torque ripple.

CONCLUSION:

In this paper, a commutation torque ripple reduction method has been proposed for brushless dc motor drives using a single dc current sensor. In such drives, the dc-link current sensor cannot give any information corresponding to the motor currents during the phase current commutation intervals. Using the commutated phase current waveforms synthesized from the measured dc current, a duty ratio control strategy has been devised to equalize the two mismatched commutation time intervals. By being directly linked with the deadbeat current control scheme, the proposed control method accomplishes successful suppression of the spikes and dips superimposed on the current and torque responses during the commutation intervals. This scheme shows attractive effectiveness in the low and the high speed regions through simulations and experiments.

REFERENCES:

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