A New Approach to Sensorless Control Method for Brushless DC Motors

 ABSTRACT:

This paper proposes a new position sensorless drive for brushless DC (BLDC) motors. Typical sensorless control methods such as the scheme with the back-EMF detection method show high performance only at a high speed range because the magnitude of the back-EMF is dependent upon the rotor speed. This paper presents a new solution that estimates the rotor position by using an unknown input observer over a full speed range. In the proposed method, a trapezoidal back-EMF is modelled as an unknown input and the proposed unknown input observer estimating a line-to-line back-EMF in real time makes it possible to detect the rotor position. In particular, this observer has high performance at a low speed range in that the information of a rotor position is calculated independently of the rotor speed without an additional circuit or complicated operation process. Simulations and experiments have been carried out for the verification of the proposed control scheme.

KEYWORDS:

1.      BLDC motor

2.      Full speed range

3.      Sensorless control

4.      Unknown input observer

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig. 1. Overall structure of the proposed sensorless drive system.

EXPECTED SIMULATION RESULTS:

       

                       

(a)    Rotor speed.

                              

(b)   Load torque.

                              

(c)    Phase current.

                       

(d)   Line-to-line back-EMF.

                               

(e)    Commutation function.

                              

(f)    Commutation signal.

Fig. 2. Response waveforms at under step change of load torque. (Speed reference: 50 rpm, Load: 0.2 → 0.5 Nm).

                                            

(a)    Rotor speed.

                                     

(b)   Load torque.

                                 

(c)    Phase current.

                               

(d)   Line-to-line back-EMF.

                              

(e)    Commutation function.

                            

(f) Commutation signal.

Fig. 3. Response waveforms under step change of load torque. (Speed reference: 1650 rpm,

Load: 0.75 → 1.5 Nm).

                                     

(a)    Rotor speed.

                                

(b)   Speed reference.

                               

(c)    Phase current.

                              

(d)   Line-to-line back-EMF.

                         

(e)    Commutation function.

                          

(f) Commutation signal.

Fig. 4. Response waveforms under step change of speed reference. (Load: 0.75 Nm, Speed

reference: 50 → 1650 → 50 rpm).

CONCLUSION:

This paper presented a new approach to the sensorless control of the BLDC motor drives using the unknown input observer. This observer can be obtained effectively by using the equation of augmented system and an estimated line-to-line back- EMF that is modelled as an unknown input. As a result, the actual rotor position as well as the machine speed can be estimated strictly even in the transient state from the estimated line-to-line back-EMF. The novel sensorless method using an unknown input observer can

v   be achieved without additional circuits.

v   estimate a rotor speed in real time for precise control.

v   make a precise commutation pulse even in transient state as well as in steady state.

v   detect the rotor position effectively over a full speed range, especially at a low speed range.

v   calculate commutation function with a noise insensitive.

v   be easily realized for industry application by simple control algorithm.

The simulation and experimental results successfully confirmed the validity of the developed sensorless drive technique using the commutation function.

 REFERENCES:

[1] N. Matsui, “Sensorless PM brushless DC motor drives,” IEEE Trans. on Industrial Electronics, vol. 43, no. 2, pp. 300-308, 1996.

[2] K. Xin, Q. Zhan, and J. Luo, “A new simple sensorless control method for switched reluctance motor drives,” KIEE J. Electr. Eng. Technol., vol. 1, no. 1, pp. 52-57, 2006.

[3] S. Ogasawara and H. Akagi, “An approach to position sensorless drive for brushless DC motors,” IEEE Trans. on Industry Applications, vol. 27, no. 5, pp. 928-933, 1991.

[4] J. C. Moreira, “Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range,” IEEE Trans. on Industry Applications, vol. 32, no. 6, pp. 1394-1401, 1996.

[5] J. X. Shen, Z. Q. Zhu, and D. Howe, “Sensorless flux-weakening control of permanent-magnet brushless machines using third harmonic back EMF,” IEEE Trans. on Industry Applications, vol. 40, no. 6, pp. 1629-1636, 2004.

Torque Hysteresis Control of BLDC Drives for EV Application by using fuzzy logic controller

ABSTRACT:

With ever increasing oil prices and concerns for the natural environment, there is a fast growing interest in electric vehicles (EVs). However, energy storage is the weak point of the EVs that delays their progress. For this reason, a need arises to build more efficient, light weight, and compact electric propulsion systems, so as to maximize driving range per charge. There are basically two ways to achieve high power density and high efficiency drives. The first technique is to employ high-speed motors, so that motor volume and weight are greatly reduced for the same rated output power. Most adjustable speed drive systems employ a single three-phase induction motor. With such a drive system, the drive has to be shut down if any phase fails. In order to improve reliability of drive systems, six-phase induction motors fed by double current source inverters have been introduced. Such a drive requires a specially wound multiphase motor but enables the motor to continue to operate at failure of any single drive unit, although it does degrade motor performance. Compared to induction motors, permanent magnet (PM) motors have higher efficiency due to the elimination of magnetizing current and copper loss in the rotor. It has become possible because of their superior performance in terms of high efficiency, fast response, weight, precise and accurate control, high reliability, maintenance free operation, brushless construction and reduced size. This project presents a current blocking strategy of brushless DC (BLDC) motor drive to prolong the capacity voltage of batteries per charge in electric vehicle applications. The BLDC motor employs a fuzzy controller for torque hysteresis control (THC) that can offer a robust control and quick torque dynamic performance. The proposed concept is verified by using Matlab/Simulink software and the corresponding results are presented.

KEYWORDS:

1.      Components

2.       Brushless DC motor

3.       Hall effect

4.       Current controller

5.       Electric vehicle (EV)

6.       Hybrid electric vehicle (HEV)

7.       Torque hysteresis controller (THC)

8.      Fuzzy logic controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                            

         

Fig 1. Structure of Optimal Current Control drive for BLDC motor.

CONTROL BLOCK DIAGRAM:

                     

       

            

Fig 2.proposed blocking strategy based on hysteresis comparator.

EXPECTED SIMULATION RESULTS:

Fig 3. Motor currents are controlled such that follow their references which are generated according to the hall effect signals (Time/div=0.5s/div).

Waveform of current and emf

Waveform of speed

Waveform 0f torque

Fig 4 (a) THC without current blocking strategy

                      

Waveform of current and emf

Waveform of speed

Waveform of torque

Fig 5.(b) THC with current blocking strategy.

CONCLUSION:

This project presented the modelling and experimental result of THC for BLDC motor. The current controller has been applied to a BLDC drive and the results shows that the current ripple stays within the hysteresis band as defined by the controller. The proposed current blocking strategy shows that the energy wastage from the batteries is prevented such that it can prolong the capacity of voltage battery and it also showed that the hysteresis controller by using fuzzy logic controller can offer inherent current protection/limitation and robustness in controlling the motor torque.

REFERENCES:

[1] Lefley, P., L. Petkovska, and G. Cvetkovski. Optimization of the design parameters of an asymmetric brushless DC motor for cogging torque minimization in Power Electronics and Applications (EPE 2011), Proceeding of the 2011-14th European Conference on 2011.

[2] Bahari N., Jidin A., Abdullah A. R. and Othman M. N., “Modeling and Simulation of Torque Hysteresis Controller for Brushless DC Motor Drives”, IEEE Symposium on Industrial Electronics and Applications ISIEA, 2012.

[3] Mayer, J.S. and O. Wasynczuk, “Analysis and modelling of a single-phase brushless DC motor drive system”, Energy

[4] Jidin, A., Idris, N. R. N., Yatim, A. H. M., Sutikno, T. and Elbuluk, M. E. „An Optimized Switching Strategy for Quick Dynamic Torque Control in DTC-Hysteresis-Based Induction Machines‟, IEEE Transactions on Industrial Electronics,2011, Vol. 58, pp. 3391-3400.

[5] Norhazilina Binti Bahari; Jidin, Auzani bin; Abdullah, Abdul Rahim bin; Md Nazri bin Othman; Manap, Mustafa bin, "Modeling and simulation of torque hysteresis controller for brushless DC motor drives," Industrial Electronics and Applications (ISIEA), 2012 IEEE Symposium on , vol., no., pp.152,155, 23-26 Sept. 2012

Current Control of BLDC Drives for EV Application

ABSTRACT:

This paper presents a current blocking strategy of brushless DC (BLDC) motor drive to prolong the capacity voltage of batteries per charge in electric vehicle applications. The BLDC motor employs a simple torque hysteresis control (THC) that can offer a robust control and quick torque dynamic performance. At first, a mathematical modeling of BLDC motor and principle of torque hysteresis control will be described, so that the benefit offered by the proposed current blocking strategy can be highlighted. It can be shown that the current control method naturally provides current limitation, in which the current error (or ripple) is restricted within the pre-defined band-gap furthermore provide current protection. The benefit of proposed current blocking strategy will be highlighted such that it can prevent the current drained from the batteries when the torque demand is released to set to 0 Nm. The control scheme is validated and verified by the simulation and experimental results.

KEYWORDS:

1.      Components

2.      Brushless DC motor

3.      Hall effect

4.      Current controller

5.      Electric vehicle (EV)

6.      Hybrid electric vehicle (HEV)

7.      Torque hysteresis controller (THC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig 1. Structure of Optimal Current Control drive for BLDC motor.

 CONTROL BLOCK DIAGRAM:

               

Fig 2. Proposed current blocking strategy based on hysteresis comparator

 EXPECTED SIMULATION RESULTS:

         

                   

Fig 3. Motor currents are controlled such that follow their references which are generated according to the hall effect signals (Time/div=0.5s/div).

                

                        

Fig 4. Waveforms of output torque, speed and currents (a) THC without current blocking strategy (b) THC with current blocking strategy.

CONCLUSION:

This paper presented the modelling and experimental result of THC for BLDC motor. The current controller has been applied to a BLDC drive and the results shows that the current ripple stays within the hysteresis band as defined by the controller. The proposed current blocking strategy shows that the energy wastage from the batteries is prevented such that it can prolong the capacity of voltage battery and it also showed that the hysteresis controller can offer inherent current protection/limitation and robustness in controlling the motor torque.

REFERENCES:

[1] Lefley, P., L. Petkovska, and G. Cvetkovski. Optimization of the design parameters of an asymmetric brushless DC motor for cogging torque minimization in Power Electronics and Applications (EPE 2011), Proceeding of the 2011-14th European Conference on 2011.

[2] Bahari N., Jidin A., Abdullah A. R. and Othman M. N., “Modeling and Simulation of Torque Hysteresis Controller for Brushless DC Motor Drives”, IEEE Symposium on Industrial Electronics and Applications ISIEA, 2012.

[3] Mayer, J.S. and O. Wasynczuk, “Analysis and modelling of a single-phase brushless DC motor drive system”, Energy Conversion, IEEE Transactions on, 1989. 4(3): p. 473-479.

[4] Jidin, A., Idris, N. R. N., Yatim, A. H. M., Sutikno, T. and Elbuluk, M. E. ‘An Optimized Switching Strategy for Quick Dynamic Torque Control in DTC-Hysteresis-Based Induction Machines’, IEEE Transactions on Industrial Electronics,2011, Vol. 58, pp. 3391-3400.

[5] Norhazilina Binti Bahari; Jidin, Auzani bin; Abdullah, Abdul Rahim bin; Md Nazri bin Othman; Manap, Mustafa bin, "Modeling and simulation of torque hysteresis controller for brushless DC motor drives," Industrial Electronics and Applications (ISIEA), 2012 IEEE Symposium on , vol., no., pp.152,155, 23-26 Sept. 2012

Transient and Steady States Analysis of Traction Motor Drive with Regenerative Braking and Using Modified Direct Torque Control (SVM-DTC)

ABSTRACT:

Direct torque control (DTC) is a suitable control method for electric drives which are supplied by inverters, specially voltage source inverters (VSI). This method has some advantages compared with other methods such as field oriented control (FOC) with some drawbacks like switching frequency variation, that leads to introduce DTC improvement methods. Using space vector modulator (SVM) in DTC structure is the most important method that is referred to as space vector modulator for direct torque control (SVM-DTC). Utilizing regenerative braking method in electrical transportation makes it necessary to analyze the traction motor behavior in regenerative braking mode. In this paper three major types of SVM-DTC are mentioned and SVM-DTC method with Closed Loop Torque and Flux Control in the Stator flux coordinates is used for simulation of traction motor driver of Ghatar Shahri Esfahan Organization. Moreover, traction motor behavior in regenerative braking mode using SVM-DTC driver is simulated.The simulation results are analyzed in the paper

KEYWORDS:

                                 1.Direct Torque Control (DTC)

                                 2. Space Vector Modulation (SVM)

                                 3. Traction Motor Drive

                                 4. Speed Control of Induction Motors

                                 5. Regenerative Braking.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of DTC

Fig. 2. Block diagram of SVM-DTC based on closed loop flux and torque control in stator flux coordinates

SIMULATION RESULTS:

                             

Fig. 3. Applied load torque at speed 0[201.4 rad/s.

                              

Fig. 4. Simulation results of SVM-DTC with reference speed of 201.4 rad/

Fig. 5. Applied load torque at speed of 170 rad/s

Fig. 6.simulation results of SVM-DTC with reference speed of 170 rad/s.

                        

Fig. 7 DC-link behavior during regenerative braking with and without regenerated energy absorption.

                              

Fig. 8. Traction motor and DC-link behavior during regenerative braking with regenerated energy absorption.

CONCLUSION:

In the case of induction traction motor control methods ,DTC has better performance. DTC has some shortcoming such as varying switching frequency proportional to motor speed variation. Therefore, it is necessary to use maximum sampling frequency in DTC. These issues result in increasing flux ripple in lower speed and increasing torque ripple in higher speed in addition to increasing switching loss. SVM-DTC with fixed switching frequency solves these problems significantly. Among different methods of electrical braking, regenerative braking has special advantages such as reduction in energy consumption and improvement in power quality of DC link. SVM-DTC operation is also appropriate and acceptable in regenerative braking. Therefore, it is suggested to utilize SVM-DTC in electric rail transportation applications

REFERENCES:

[1] Sergaki, E.S.; Moustaizis, S.D., "Efficiency optimization of a direct torque controlled induction motor used in hybrid electric vehicles," Electrical Machines and Power Electronics and 2011 Electro motion Joint Conference (ACEMP), 20111nternational Aegean Conference on , vol., no., pp.398,403, 8-10 Sept. 2011

[2] Zhongbo Peng; XueFeng Han; Zixue Du, "Direct Torque Control for Electric Vehicle Driver Motor Based on Extended Kalman Filter," Vehicular Technology Conference Fall (VTC 201 a-Fall), 2010 IEEE 72nd , vol., no., pp.I,4, 6-9 Sept. 2010

[3] Rehman H, Longya X. Alternative energy vehicles drive system: control, flux and torque estimation, and efficiency optimization. IEEE Trans Veh Technol 2011; 60:3625-34.

[4] Rongmei, P. L., et al. "A Novel Fast Braking System for Induction Motor. " international Journal of Engineering and innovative Technology (IJEIT), vol. 1,2012.

[5] H. Abu-Rub, A. Iqbal, and 1. Guzinski, "Direct Torque Control of AC Machines," in High Performance Control of AC Drives with MATLABISimulink Models, John Wiley & Sons, Ltd, 2012, pp. 171-254.