The Design and Simulation of Electro-Hydraulic Velocity Control System

Transcription

1 Te Design and Siulation of Electro-Hydraulic Velocity Control Syste Fengtao in * Key aboratory of Ministry of Education for Conveyance and Equipent, East Cina Jiaotong University, Nancang , Cina enggu_lin@163.co Abstract. In tis paper, te principle of electro-ydraulic proportional control syste are introduced, electro-ydraulic velocity control syste are designed and can realize volevity control wit ig accuracy. In te syste, relative aplitude abundant degree and pasic abundant degree and corresponding frequency of passing of Body syste is easily obtained under different open ring gain of K, tus it is siple and accurate to coose reasonable paraeters, and ten can carry on sulation to syste by Matlab/Siulink to exaine te design results. Keywords: Electro-ydraulic servo syste, Matlab, Siulation. 1 Introduction Velocity control syste[1,]is widely used in practical projects need for velocity control, suc as turrets, radar, turntable, etc; and te projects need for straigt line otion velocity control, suc as lifting platfor, ail-sorting acine autoatically conveyor, acine tool feeding device, etc. velocity control syste wit electro-ydraulic servo controller is a control circuit tat output velocity variation feeds back to te input side via te sensor. In electro-ydraulic velocity control syste[3,4] designing, te traditional approac is to identify te syste coposition and control ode based on te requireents, ten to build te ateatical odel and te syste paraeters, and adjust te open loop gain K of te syste to ensure te syste stability based on te bode diagra or nyquist diagra analysis of te open loop transfer function. In tis paper, open-loop transfer function of a syste was described use atlab language, te aplitude argin, pase argin, and te corresponding crossover frequency of te relatively stable syste can be calculated after evaluating te K value. According to te critical condition of te syste stability argin, te K value is adjusted and te new gain argin and pase argin were calculated repeatedly until at least one of te argins close to te critical condition steadily at te preise of all stability conditions are eet. and te paraeters k value was decided. In tis way, te open loop syste aplitude and crossover frequency increased as uc as possible, and also ensure te syste stability. A rotating device velocity control syste design of an equipent was presented as an exaple to illustrate te application of tis etod. * Corresponding autor. Tel.: D. i, Y. iu, and Y. Cen (Eds.): CCTA 0, Part IV, IFIP AICT 347, pp , 011. IFIP International Federation for Inforation Processing 011

2 Te Design and Siulation of Electro-Hydraulic Velocity Control Syste 569 Metods and Applications A device rotator syste paraeters are defined as follows[5]: oad rotational inertia J = 0.4 kg, rotational velocity range n =35 00 r/in, Working Pressure p =8MPa, Maxiu load torque M =50N, static gain of velocity Sensor is 0V /00 r in 1, and perforance index requireents are defined as follows: tracking precision is ±1 r /in, copleting te tracking task accurately witin 0.15 s..1 Working Principle of te Contronl Syste As te control power is saller, so valve- controlled electro-ydraulic syste[6] is doinated directly by te servo valve. Te working principle is sown by Fig. 1. ui + ue I Q θ u f θ Fig. 1. Diagra of syste working principle Were, u i is velocity contronl singal; e valve flow; θ is output velocity; u is feedback. ' f u is deviations; I is input current; Q is servo. Motor Discarge In tis paper, axiu load value is two-tirds of supply oil pressure value and is found to be: P 8 6 P 5.3MPa = = = (1) 3 3 π M otor discarge is found to be: D = = = /rad 6 π P 5.3 Te BM1 type cycloid ydraulic otor was selected, and te discarge D is: /rad.

3 570 F. in.3 Servo Valve Specifications Deterination Te servo valve flow is found to be: Q pressure drop is: = = 7 πdnax π p = p p = = V 3 3 = 0.4 /in, Pa QDYIC63 type servo valve can eet te paraeters requireents, and it s rated no-load flows Q 3 3 V is 1.05 /s,rated current I V is 0.03A, supply oil pressure is Pa..4 Te Dynaic Caracteristic Deterination Control syste diagra is sown as figure,were, K is integral aplifier gain, KV is servo valve gain, ξ V is daping ratio of te servo vaulve, V is natural fre- is natural fre- quency of servo valva; D is te ydraulic otor displaceent, quency of ydraulic otor, ξ is te daping ratio of ydraulic otor. a ui + u V e K I Q a s ξv S + s + 1 V V u f K K T s 1 D ξv + s + 1 θ θ Fig.. Control syste diagra 1) te transfer function of electro-ydraulic servo valve te servo valve gain is defined as follows: 3 QV KV = = = 3.5 /sa () IV 0.03 Dynaic paraeters of servo valve are decided in accordance wit saple values, and natural frequency V is 340 rad / s, daping ratio ξ V is 0.70, so te transfer function expression can be prescripted as follows: Q I = s s (3)

4 Te Design and Siulation of Electro-Hydraulic Velocity Control Syste 571 ) Te transfer function of ydraulic otor By calculation, te total volue of otor oil cavity and te volue between servo 6 3 valve to te otor is V t = 50, effective volue elasticity coefficients 5 β = 7000 Pa,So natural frequency expression of otor can be defined as follows: e 4βeD = = 193 (4) JV and daping ratioξ = 0., ten te transfer function of ydraulic otor can be sown as follows: 1 ' 7 5 θ (5) = = Q s 0. s 0. + s+ 1 + s t 3) Transfer function of velocity sensor deterination Static gain of velocity sensor is 0 V/r in 1, K = 0.0 T V/r in 1 = 0.19 V s/rad transfer function of integral aplifier is defined as follows: I u e Ka = (6) S.5 Integral Aplifier Gain Deterination Transfer function of open loop syste is defined as follows: WS ( ) Ka = s 0.7 s 0. s + s+ 1 s (7) 5 K = Ka = 170Ka Based on Bode diagra of te syste, te crossover frequency of te corresponding pase; G is te stable aplitude argin, Wcg is p is pase argin, Wcp is te crossover frequency of te corresponding aplitude. For te control engineering practice, stability argin ust be ensured, so te paraeters of te syste are prescribed as follows: G > 6dB, tat is: G > ; p 30, Te syste is single input-output syste, te progra was designed as follows:

5 57 F. in Te results are sown as follows: su = [K]; den1 = [1/340^ 1.4 / ] ; den = [0 1 /193^ 0.4 /193 1 ] ; den = conv(den1,den); sys =tf(su,den); [ G, p, Wcg, Wcp ] =argin(sys) Table 1. Results of te progra operation In tis paper, K =36.9 based on te analysis of table 1,and so tere be: 36.9 Ka = = Transfer function of open loop syste was sown as follows: W( S) 36.9 = s 0.7 s 0. s + s+ 1 s (8) (9).6 Te Steady-State Syste Error Te open loop syste is 1 type syste because te introduction of an integral part. Te error of syste response to velocity instruction is zero, wic can fully eet te tracking accuracy requireents of ± 1 r / in..7 Syste Siulation and Results Syste siulation diagra is sown by Fig. 3. and siulation results of syste response to step signals is sown by Fig. 4.

6 Te Design and Siulation of Electro-Hydraulic Velocity Control Syste 573 Fig. 3. Syste siulation diagra Fig. 4. Siulation results of syste response to step signal Te siulation results sow tat te existing syste is stable and non-oversoot, te increasing process was not onotonous, wit a few sall oscillations. te transition process witin 0.11 s, and quickly reac convergence. so te syste can coplete te tracking task accuratly witin 0.5s, te volecity control syste design is eet te requireents very well. 3 Conclusion 1) In te velocity control syste designing, relatively stable aplitude argin, pase argin, te crossover frequency of te corresponding pase and reasonable syste paraeters can be easy to calculated accurately based on te siulation of open loop syste use atlab language. ) Siulation on te designed syste using atlab/siulink can predict te results, verify correctness and provide a reference for designers. Availability of te siulation results depends on te correctness of te ateatical odel, so rational odel and paraeters selection of te syste are iportant. Acknowledgeent. Tis work was sponsored by Supported by Foundation of Jiangxi Educational Coittee(GJJ09).

7 574 F. in References 1. i, H.: Hydraulic control syste. National Defence Industry Press, Beijing (February 1981). Wang, C.: Hydraulic servo control syste. Cina Macine Press, Beijing (1993) 3. Eryilaz, B., Wilson, B.H.: Unified Modeling and Analysis of a Proportional Valve. Journal of te Franklin Institteu 343(1), (006) 4. iu, J.-R., Jin, B., Xie, Y.-J., Cen, Y., Weng, Z.-T.: Researc on te electro- ydraulic variable valve actuation syste based on a tree-way proportional reducing Autoovalve. International Journal of tive Tecnology (1), 7 36 (009) 5. Guan, J.T.: Electro ydraulic Control Tecnique. Tongji University Press, Sangai (003) 6. Wang, C.: Electro-Hydraulic Servo Control Syste. Cina Macine Press, Beijing