Double Closed-loop Control System Design of PMSM Based on DSP MoupengTao1, a,songjianguo2, b, SongQiang3, c

Transcription

1 4th International Conference on Mechatronics, Materials, Chemistry an Computer Engineering (ICMMCCE 2015) Double Close-loop Control System Design of PMSM Base on DSP MoupengTao1, a,songjianguo2, b, SongQiang3, c 1 College of Electronic Information an Control Engineering, Beijing University of Technology, Beijing, , China 2 College of Electronic Information an Control Engineering, Beijing University of Technology, Beijing, , China 3 College of Electronic Information an Control Engineering, Beijing University of Technology, Beijing, , China a @163.com, b sjglcy@163.com c @qq.com Keywors: PMSM; Vector control theory; Double close loop control system;svpwm;dsp Abstract. In this paper, the vector control theory of PMSM is stuie, an the ouble close-loop control system of PMSM is esigne. By analyzing the mathematical moel of PMSM, vector control principle an control strategy base on vector control, the control strategy an realization metho of this paper are etermine. The operating principle an algorithm of space vector pulse with moulation (SVPWM) are analyze. The SVPWM an the whole control moel are simulate by Matlab/Simulink. Finally, the harware system is built with TMS320F28335 TI as the control core. The control system is teste. The test results prove the practicability an effectiveness of the control system. Introuction Vector control system [1]of PMSM is a kin of high performance AC control system, which has the avantages of simple structure, small size, light weight, high efficiency, high overloa capacity, small inertia an small torque ripple. Because of the current loop, the current loop is ecouple into DC control, which can achieve DC control performance. The current loop can hanle the problem of its pulse. Because of the high spee loop, the current loop is given. The three-phase AC motor is controlle by the vector control theory. The three-phase stator current is ecouple into the torque current an exciting current by the coorinate transformation, an the control strategy is easy to achieve a goo control performance[2]. PMSM vector control principle an mathematical moel Vector control theory solve the problem of AC motor rive strategy incluing PMSM, so that the AC motor can be controlle like a DC motor. The metho is: by means of coorinate transformation, the electric potential of the armature in the stationary two-phase coorinate system can be ecompose into the irect axis electric potential an the quarature axis. An the two components are mutually perpenicular, so we can ajust them separately in orer to achieve the control effect of similar irect current motor[3]. The coorinate transformation is the basis of analyzing the mathematical moel of PMSM an its control strategy. Because the coorinate transformation can be use for the AC motor in the three-phase AC wining is equivalent to two phase vertical AC wining an two phase rotating DC wining, which will greatly simplify the analysis an control of AC motor. Vector control in the coorinate system use in three: The authors - Publishe by Atlantis Press 1471

2 (a)three phase AC wining (b)two phase AC wining(c)rotary DC wining Fig.1. Physical moel of the motor wining In vector control, the coorinate transformation is mainly refers to the transformation of the three phase static ABC coorinate system to the two-phase static coorinate system, the Clark transform an the two-phase rotating coorinate system, the Park transform an the inverse transform. By means of coorinate transformation, we can get the mathematical moel of the PMSM uner the q coorinate system with the mathematical moel of the three phase stationary ABC coorinate system[4][5]. Voltage equation: u q Rsi 1 t q uq Rsiq 2 t Flux linkage equation: Li 3 f q Lqiq 4 Electromagnetic torque equation: 3 3 Tem p( iq qi ) p[ f iq ( L Lq ) iiq ] Motor motion equation: J Tem TL p t 6 The electromagnetic torque equation is ivie into two parts. The first part is the electromagnetic torque generate by the interaction between the current an the permanent magnet. In the secon part, it is cause by the effect of the rotor, which is calle the reluctance torque. Uner the effect of rotating magnetic fiel of stator, the asymmetry of the magnetic fiel of the cross shaft an the axis of the shaft is proportional to the ifference between the shaft an the shaft. So we can control the size an irection of the electromagnetic torque by controlling the size an irection of the DQ axis current, an then control the motor rotation. Double close-loop control system esign an SVPWM The PMSM control system is compose of current loop an spee loop. An the performance of the whole system is the basis of the whole system performance, an the performance of the outer ring is epenent on the optimization of the inner loop. Current loop is the basic of high performance control system. The ynamic response of the system is irectly relate to the 1472

3 realization of vector control strategy, an also irectly affects the ynamic performance of the whole system. Spee loop is also an extremely important link. The control performance is an important part of the system control performance[6]. In a broa sense, spee servo control shoul have high accuracy an fast response characteristics. Fig.2. Double close loop control system structure iagram Accoring to the ynamic structure iagram of the motor, the spee loop is opene. The electromagnetic time constant of the motor is much less than the mechanical time constant. An because the anti electromotive force an spee is proportional to the spee loop, but a slow change in the current loop in the process of rapi ajustment, it can be consiere. This oes not take into account the effect of the potential feeback, thus simplifying the current loop structure, an the transfer function of the current loop of the controlle object is: G s T s 1 Rs After the current regulator 1 is ae, the ynamic structure of the current loop is shown in Fig3[7]. After the current regulator is correcte, the transfer function is a typical I type. The current loop an the controlle object are use as the control object in the spee loop. After correction of the open loop function: n s 1 G K After correction, the ynamic structure of the spee loop is s N 2 s ( T s 1) n shown in Fig4. Fig.3.Current loop ynamic structure Fig.4.Dynamic structure iagram of spee loop In summary, accoring to the specific parameters of permanent magnet synchronous motor, the spee current controller can be esigne accoring to the engineering setting metho, an the spee current controller is esigne, an then the PI parameters are etermine accoring to the actual situation. Double close loop system topology is shown in Fig5: Fig.5.Double close loop system topology Vector Pulse With Moulate Space (SVPWM) is an important part of vector control. Through frequency conversion to achieve the motor spee control strategy, the motor control of the regulator is ajuste, the final will be transforme into PWM as the inverter switch evice on the conuction an off signal. As the last part of the control strategy, the performance of the control system is very important. SVPWM has the avantages of high utilization rate, low harmonic components an low power consumption. It can be use in combination with the vector control algorithm to maximize the performance of the evice. Therefore, the application of SVPWM in motor frequency conversion spee control system is more frequent[8]. 1473

4 System simulation After the research an analysis of the permanent magnet synchronous motor an its control strategy, we nee to simulate the whole control system, an set provie reference for our esign. we establish the simulation moel of the coorinate transformation moule, SVPWM moule an control system in Matlab/Simulink environment. Finally, the whole control system is simulate an the simulation results are analyze. First, the PMSM plus a fixe loa torque, at the same time given an electromagnetic torque value, the simulation results are shown in the following figure: (a)sector N (b)time switching point (c) Phase voltage ()Line voltage Fig.6.Simulationg results of SVPWM From the above picture (b), we can see that the moulation waveform obtaine by SVPWM moulation is sale shape, which is beneficial to improve the voltage utilization. From the () line voltage waveform we can get, the SVPWM moulation moe can make the line voltage peak is equal to the DC bus voltage, relative to the SPWM, improve the voltage utilization. SVPWM can better control the inverter, so that the phase voltage is 6 step wave. PMSM plus a fixe loa torque, while a given electromagnetic torque values, the simulation results obtaine as shown below: (a)rotational spee (b) torque (c) phase current () line voltage Fig.7.Simulationg results of constant torque From the above (a) an (b) can be seen, the motor spee of the motor increases with the torque, the final rive torque an loa torque to achieve a balance, spee is also stable at a fixe value. (c) in the phase current of the simulation shows that the amplitue of the phase current increases, the final magnitue of the same, an the frequency is not the same as the line voltage waveform, amplitue also reache the DC bus voltage value, the frequency remaine unchange. Seconly, given the PMSM loa torque, the torque is given, the simulation results are shown in the following iagram: (a)rotational spee (b) torque (c) phase current () line voltage Fig.8.Simulationg results of variable torque Due to the beginning of the torque is greater than the loa torque, spee up, an then stabilize at a fixe value, when the simulation time reaches 0.25s, the torque value of the given value is small, the riving torque an the loa torque is not balance, the spee an then ecrease, an finally stable at the other fixe spee, rive torque an loa torque to achieve balance. We can see from the 1474

5 three phase current waveform, the given value of the torque is reuce, the stator current amplitue is reuce, an the frequency is also reuce. The with of the line voltage waveform is also increasing, an the frequency is ecreasing. Harware esign an Test results The whole control experiment platform has the following parts: the host computer, the main control boar, the isolation rive boar, the IPM inverter moule an the PMSM. The main control boar an IPM moule between the nee to a a separate river boar to isolate the river signal. The main control boar is mainly on the sampling circuit, communication circuit, level conversion circuit, rotating transformer ecoing circuit an the main control chip TMS320F28335 minimum system circuit. The main circuit of the system is supplie by DC power supply, an the IPM inverter moule is supplie to the PMSM power supply, an the riving signal of the inverter is provie by the main control boar which is separate by the six PWM signal. The rotor position of the PMSM has a rotating transformer to etect, an the etection signal passes through the SPI bus an the main control chip is in communication with the main control chip. The host computer through CAN communication to transmit system given signal an control switch signal, an receive a variety of sampling signal. Fig.9.Harware system iagram The motor control program is ownloae to the DSP, an the CCS compiler is ebugge online, an the output of the sub moules is observe. CCS not only can monitor the changes of the variables, but also provies a graphical monitoring interface, which can observe the change of a variable. The DSP output waveform receive IGBT river, accoring to the principle of the IGBT main circuit esign: if you want to open the IGBT security an reliability, the riving voltage shoul be +15V an -8V, as shown in figure. DSP output of the PWM signal for +3.3V an 0V, after riving the circuit can output +15V an -8V rive signal, inicating that the river circuit esign to achieve the esire requirements. Fig.10.Driver boar output SVPWM waveform Fig.11.Spee close loop 1475

6 Conclusion In this paper, the principle of vector control is introuce. Base on the mathematical moel of PMSM in rotating q axis coorinate system, the vector control principle an vector control scheme are escribe in etail. Base on the control scheme of this paper, the harware system base on TMS320F28335 is built, an the control system is teste. The experimental results show that the control system is feasible an correct. References [1] Wang Chengyuan. Vector control AC servo rive motor [M]. Machinery Inustry Press, 1995 [2] Morimoto S, Takea Y, Hirasa T, et al. Expansion of operating limits for permanent magnet motor by current vector control consiering inverter capacity[j]. Inustry Applications, IEEE Transactions on, 1990, 26(5): [3] Tang RenYuan Moem permanent magnet machines theory an esign)[j] [4] Pillay P, Krishnan R. Moeling of permanent magnet motor rives[c]//robotics an IECON'87 Conferences. International Society for Optics an Photonics, 1987: [5]Morimoto S, Takea Y, Hirasa T, et al. Expansion of operating limits for permanent magnet motor by current vector control consiering inverter capacity[j]. Inustry Applications, IEEE Transactions on, 1990, 26(5): [6] LiJian.Design an implementation of the three close loop AC permanent magnet synchronous motor servo system base on DSP [M]University of Electronic Science an technology.2007 [7]Jagaish H Pujar, S.F. Koa,Digital Simulation of Direct Torque Fuzzy Control of PMSM Servo System[C],International Journal of Recent Trens in Engineering,2009:89-93 [8]Zhang Qinglu.Design of control system for permanent magnet synchronous motor[m]beijing University of Technology,