Optimal Control for Single-Phase Brushless DC Motor with Hall Sensor

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1 Reearch Journal of Applied Science, Engineering and Technology 5(4): 87-92, 23 ISSN: ; e-issn: Maxwell Scientific Organization, 23 Submitted: June 22, 22 Accepted: Augut 7, 22 Publihed: February, 23 Optimal Control for Single-Phae Bruhle DC Motor with Hall Senor Dawei Meng, 2 Xifeng Wang, Yongming Xu and Yufeng Lu Harbin Univerity of Science and Technology, Harbin, 58, China 2 Heilongjiang Intitute of Technology, Harbin, 55, China Abtract: Thi tudy deal with the optimization control of a ingle-phae bruhle DC motor (BLDCM) with Hall enor. A imple modeling method with feaible parameter identification i adopted to meet characteritic of inglephae BLDCM. With the linear Hall enor feedback, the advantage of current-mode control cheme and oftcommutation cheme are propoed to achieve maximum efficiency over the entire peed range. Thi thei alo develop a low-cot and high efficiency control for ingle-phae BLDCM. The hardware tet platform ha been contructed on a ingle-chip Field Programmable Gate Array (FPGA) of Cyclone II Family of Altera to verify the performance and feaibility of the propoed optimization control trategie. When uing the control cheme with Hall enor, experimental reult how that there are at leat a % improvement for average value of dc-link current, a % improvement for RMS value of phae current and a 4% improvement for peak value of phae current. Keyword: BLDCM, FPGA, hall enor, optimization control method INTRODUCTION Along with the rapid development of economy, it i eential for the electronic product to be elaborated and ophiticated and the internal function are variou and high peed. The phae winding of BLDCM can be claified a ingle-phae or 3-phae, their flux ditribution can be either inuoidal or trapezoidal. Single-phae BLDCM i le expenive and eaier to manufacture compared to 3-phae BLDCM and i widely ued in low-cot and low-power application. However, it exhibit zero torque point at certain rotor poition. Even though thee dead point could be avoided by applying an aymmetric air gap, thi deteriorate motor characteritic in torque and efficiency. Becaue of rapid development of integrated circuit, the integration of control and drive IC have been widely implemented in BLDCM. The linear Hall enor provide the information of rotor poition and velocity via ignal proceing technique. However, there are ome unuitable for high temperature environment. Sun et al. (27) analyze the drive of ingle-phae bruhle dc motor baed on torque. Rubaai et al. (22) have a reearch of the development and implementation of an adaptive fuzzy-neural-network controller for bruhle drive. Son et al. (28) tudy the integrated MOSFET inverter module of low-power drive ytem. Xia et al. (29) have a tudy of the control trategy for fourwitch 3 phae bruhle dc motor uing ingle current enor. Su and Mckeever (24) analyze the low-cot enor le control of bruhle dc motor with improved peed range. Pan and Fang (28) tudy a phae-lockedloop-aited internal model adjutable-peed controller for BLDC motor. Sathyan et al. (29) have a reearch of the FPGA-baed novel digital PWM control cheme for BLDC motor. Liu et al. (27) analyze the commutation torque ripple minimization in directtorque-controlled pm bruhle dc drive. With the development of digital integrated circuit, digital motor control ytem have been widely implemented with oftware and hardware baed on microcontroller or FPGA. Thee approache provide flexibility and are uitable for motor drive application. For imple tructure and requirement of ingle-phae BLDCM motor, it eay to employ to lim type application of conumer electronic. Moreover, due to the characteritic of wide peed range, mall ize, eay controllability and long lifetime expectancy, ingle-phae BLDC motor are now the major choice for forced air cooling in PC, NB and other information appliance. The propoed control cheme have been implemented on a ingle-chip FPGA controller to verify the performance and feaibility for ingle-phae BLDCM. Experimental verification ha been carried out on a ingle-phae BLDCM control ytem. STRCTURE AND MATHEMATICAL MODELING Figure how an initially deigned ingle-phae BLDCM. It i an outer rotor type and conit of 4 pole Correponding Author: Xifeng Wang, Heilongjiang Intitute of Technology, Harbin 55, China 87

2 Re. J. Appl. Sci. Eng. Technol., 5(4): 87-92, 23 vemf = KE ω (2) r where, ω r : The rotor velocity K E : The back-emf contant which i aociated with the form of nonlinear flux ditribution in thi application Fig. : The overall diagram of our method and four lot. To olve the optimum problem, effective deign variable capable of ignificantly influencing the objective function need to be choen. The marked feature of ingle-phae BLDCM i the aymmetric air gap to eliminate dead point. If dead point, where the developed torque value i zero, exit in ingle phae BLDCM, there i a poibility that the motor will top at the dead-point and be unable to tart. The tator winding can be modeled a a winding reitance in erie with a winding inductance and a back-emf voltage. The voltage equation decribing the dynamic behavior of ingle-phae BLDCM i given a follow: di v = L + ir + v () emf dt where, v : The phae voltage i : Phae current R S : The winding reitance L S : The winding inductance v emf : The back-emf voltage induced by rotor flux variation and the value i proportional to motor peed and can be computed by: For the mechanical ytem, the developed torque mut overcome the inertial acceleration torque, friction torque and the load torque. Therefore, the torque-peed characteritic can be formulated a: dω T = J + B ω + T dt r e m m r L (3) where, the inertial acceleration torque i repreented by the product of the moment of inertia J m and the angular acceleration dω r /dt. The load torque referred to the motor haft, while the friction torque i the product of the rotor velocity and vicou friction coefficient B m. According to previou equation, the modeling of ingle-phae BLDCM can be repreented by a block diagram a hown in Fig. 2: MODEL VERIFICATION According to previou decription, a imple modeling method with an illutrated parameter identification cheme for ingle-phae BLDCM ha been propoed. Uing the open-loop voltage-mode of hard-commutation cheme (Fig. 3) how the conitency of the propoed model and the real motor, it can be een that imulation reult are cloe to experiment meaurement under different duty ratio. Figure 4 how the RMS value of phae current and rotor peed curve under different duty ratio, the imulation reult i alo cloe to experiment Inverter R B m v a vb vab PWM φ f θ e L Flux Ditribution Table T e K T T L T L J m 2 TL = Kωr ω ω r Commutation Control v emf K E H Hall Senor θe Fig. 2: Block diagram for modeling of the ingle-phae BLDCM 88

3 Re. J. Appl. Sci. Eng. Technol., 5(4): 87-92, 23 meaurement. That i, above of all confirm the validity of the propoed model. EFFCIENCY OPTIMATIZATION CONTROL SHEME (a) Both of hard-commutation and oft-commutation cheme are till enitive to the rotor flux ditribution, o the overall efficiency will be eriouly degraded in wide peed control application. Thi reearch develop the efficiency optimization control cheme baed on cloed-loop current-mode control cheme for inglephae BLDCM. Moreover, the advantage of oft-commutation control at high peed operation will be adopted to widen the peed control range and to reduce the current pike. Thi reearch ue the digital PI controller to realize the current-regulation which enure that the meaured tator current track the required value accurately and to horten the tranient interval a much a poible. Figure 5 how the continuou time equivalent of current-loop control ytem, where the controller block i repreented by typical PI regulator tructure. The controller deign i typically baed on pecification concerning the required cloed loop bandwidth and phae margin. In our application, we uppoe that the ytem bandwidth f CL equal to about one tenth of the witching frequency and at leat a 45 degree phae margin PM. So, parameter K P and K I have to determine to guarantee thee requirement. HARDWARE TEST PLATFORM AND EXPERIMENTAL RESULT ANALYSIS (b) Fig. 3: Phae current comparion between imulation reult and experiment meaurement (a) duty = %, (b) duty = 5% RMS current (ma) Experimental reult Simulation reult Duty (%) Fig. 4: The RMS value of phae current and rotor peed curve The microelectronic technologie have become a major trend. The digital control cheme ha the advantage of imple circuitry, oftware control and flexibility in variou application. In order to verify the validity of the developed control trategie with linear Hall enor, a FPGA-baed control ytem i etup for the experiment. Two fat periodic interrupt with 2 khz perform the A/D converter ynchronization, PWM generation, enor algorithm, tart-up control and current-loop control. It hould be noted that both the control algorithm with, are realized in thi ISR. The ynchronou ampling technique i adopted to ene the phae current. The FPGA controller perform the real-time control algorithm, including the PI algorithm, tart-up control and cloed-loop current-mode control. Experiment on the developed control trategie with Hall enor are carried out. Uing the ingle-phae BLDCM drive etup decribed in the previou ection, the ytem 89

4 Re. J. Appl. Sci. Eng. Technol., 5(4): 87-92, 23 PWM module * i + - PI module KI KP + Static gain v tri Delay module TSW 4 TSW + 4 Motor model V DC R + L Inverter gain i K ADC H Current enor Fig. 5: The continuou time equivalent of current-loop control ytem (a) (b) Fig. 6: Steady-tate repone when uing the open-loop voltage-mode control of hard commutation cheme (a) 4 RPM, (b) 3 RPM, (c) RPM (c) (a) (b) Fig. 7: Steady-tate repone when uing the oft-commutation cheme (a) 4 RPM, (b) 3 RPM 9

5 Re. J. Appl. Sci. Eng. Technol., 5(4): 87-92, 23 Average value of dc-link current (ma) Hard-commutation control cheme Soft-commutation control cheme Current-loop control cheme Current-loop+oft-commutation cheme Speed (RPM) Fig. 8: The tep repone of current-loop control ytem at zero current by 4 ma tep input performance are evaluated for variou teady-tate and tranient operating condition. The teady-tate repone when uing the open-loop voltage-mode control of hard-commutation cheme at 4, 3 and RPM, repectively. The waveform can be een in Fig. 6. Figure 7 how the teady tate repone when uing the open-loop voltage-mode control of oftcommutation cheme at 4, 3 and RPM, repectively. In Fig. 7(a), the phae voltage waveform exit a blanking time of 5% commutation cycle. Beide, from phae current waveform, there are a 4% reduction of peak value and a % reduction of RMS value. However, In Fig. 7(b), the blanking time i horten to 5% commutation cycle and the improvement of peak current i only 5% and RMS current i only 2%. A expected, the oft-commutation control i only uitable for high peed operation. The efficiency optimization control cheme i the combination of cloed-loop current-mode control for low and middle peed operation and open-loop voltagemode control of oft-commutation cheme for high peed operation. Figure 8 how the tep repone of current-loop control ytem at zero current by 4 ma tep input. Uing the ingle-phae BLDCM drive etup decribed in the previou ection, the ytem performance are evaluated for variou teady-tate and tranient operating condition. In order to verify the propoed control trategy, the overall efficiency i compared by variou control cheme. Figure 9(a) how the average value of dc-link current veru rotor peed. For entire peed range, the curve of hard- commutation control cheme ha higher value than other control method, which mean that it need more input power to drive the fan motor at the ame peed. Figure 9(b) how the RMS value of phae current veru rotor peed. Similarly, the developed control cheme ha relatively lower value for four method, which mean that it ha higher utility ratio of 9 RMS value of phae current (ma) Peak value of phae current (ma) (a) Average value of dc-link current veru rotor peed (b) RMS value of phae current veru rotor peed Hard-commutation control cheme Soft-commutation control cheme Current-loop control cheme Current-loop+oft-commutation cheme Speed (RPM) Hard-commutation control cheme Soft-commutation control cheme Current-loop control cheme Current-loop+oft-commutation cheme Speed (RPM) (c) Peak value of phae current veru rotor peed Fig. 9: Statitic curve of variou control cheme current and o a to electrical output power for fan motor. Figure 9(c) how the peak value of phae

6 Re. J. Appl. Sci. Eng. Technol., 5(4): 87-92, 23 current veru rotor peed. Obviouly, the peak value ha ignificant reduction for entire peed range and thi will reduce the acoutic noie and power circuit rating. CONCLUSION Thi tudy preent the efficiency optimization control for ingle-phae BLDCM with Hall enor. The control cheme ha been verified by computer imulation baed on the propoed model. Beide, the drive ytem i implemented by FPGA and ome experimental reult have been hown to verify the performance and feaibility. Thi tudy preent an efficiency optimization control cheme for ingle-phae BLDCM with linear Hall enor. To produce the maximum output power, the each back-emf control ytem with Hall enor on a digital ignal proceing hardware platform. The FPGA controller perform the real-time control algorithm, tart-up control and current-loop control, etc. Then, the practical realization iue and analye of experimental reult are alo preented. In ummary, thi tudy preent efficiency optimization control for ingle-phae BLDCM with Hall enor. The developed control trategie are firt verified by propoed model and then fulfill on a real ingle-phae BLDCM with Hall enor baed on FPGA controller. REFERENCES Pan, C.T. and E. Fang, 28. A phae-locked-loopaited internal model adjutable-peed controller for BLDC motor. IEEE T. Ind. Electron, 55(9): Rubaai, A., D. Rickett and M.D. Kankam, 22. Development and implementation of an adaptive fuzzy-neural-network controller for bruhle drive. IEEE T. Ind. Appl., 38(2): Sathyan, A., N. Milivojevic, Y.J. Lee, M. Krihnamurthy and A. Emadi, 29. An FPGAbaed novel digital PWM control cheme for BLDC motor. IEEE T. Ind. Electron, 56(8): Son, Y.C., K.Y. Jang and B.S. Suh, 28. Integrated MOSFET inverter module of low-power drive ytem. IEEE T. Ind., 44(3): Su, G.J. and J.W. Mckeever, 24. Low-cot enorle control of bruhle DC motor with improved peed range. IEEE T. Power Electr., 9(2): Sun, L., Q. Fang and J. Shang, 27. Drive of inglephae bruhle DC motor baed on torque. IEEE T. Magn., 43(): Xia, C., Z. Li and T. Shi, 29. A control trategy for four-witch 3 phae bruhle DC motor uing ingle current enor. IEEE T. Ind. Electron, 56(6): Liu, Y., Z.Q. Zhu and D. Howe, 27. Commutation torque ripple minimization in direct-torquecontrolled PM bruhle DC drive. IEEE T. Ind. Electron, 43(4):