Journal ofScience & Technology 102 (2014) 001-005 Cascade Sliding Mode Control of DC Motor Nguyen Xuan Anh, Nguyen Huy Phuong, Nguyen Quang Dich * Hanoi University ofScience and Technology No.l Dai Co Viet Str HaNol VietNam Received: March 04, 2013; accepted: April 22, 2014 Abstract This paper deals with a sliding mode control technique as a novel solution for separately excited DC motor speed control The basic principle of cascade sliding mode control method is also introduced thereafter Then, the performance of SMC is assessed via ^AATLAB simulation using a personal computer and model of the DC motor The simulation result shows that the sliding mode controller (SMC) has many advantages for the speed control of DC motor Keywords: Sliding mode control; Speed control; DC motor Tom tat Bai bao trinh bay mot l \L— -t Ri-\" \ dt ,,,, 2TJ , dn d n dt dt' Jf„V •) + -, (10) - {m,^c -• Kipnl ' \ dt L Simulation result To abide by the sliding condition: ss < , which means that sliding phenomenon can occur in s ^ b Velocity control In traditional cascade method to design controllers for DC Motor, the speed controller in an outer loop, the current control loop in an inner loop and may be treated as an ideal current source This happens because the electrical time constant is much smaller than the mechanical time constant Similarly, with SMC, we also apply that principle The outer loop will supply the reference armature current /* to feed the inner loop The sliding surface and discontinuous control are set up interns of the output speed error as; de S = ce ^ , /* (7) I = ZoSign(s) Where, c is a positive constant to be chose by the designer such that polynomial F(s) = c + is a Hurwitz polynomial, which graduates roots e(t) of the equation (7) s(t) = always satisfy for all initial The controllers designed in Section III are simulated wdth DC Motor of Siemens No, 1GH5 1020ED40 - 4TV1 on MATLAB techmcal software Simulation parameters of the DC motor used for simulation are listed below It is supposed that armature resistance and inductance are various parameters in a range about ±15% The control method will be verified through some following simulation scenarios Fig 4.1 illustrates the response of the armature current of the sliding mode current controller used when appearing a current step with starting at 7A and rose to 5.4A after 0.005 seconds f i g and Fig display the motor speed and controlled armature current when the reference speed «* has the change as step signal, Imtially, the reference speed is a half of the rated speed 585rpm, and after 0,2 seconds this figure is set at the rated speed by 1170rpm Fig 4.4 is control voltage, which oscillates with frequency l700Hz and 220Hz, respectively For both reference values, output speeds and armature current are stable after approximate 0.02 seconds Table 1, Simulation Parameters ir MO) ^ inputs e(U) , —^-^ so that: Armature Resistance Similar to current control, we also have a Lyapunov function candidate is positive definite fiinction: Xt) V{t) /fa-10 ± % Armature Inductance i,fl-0,0405H±15% Torque of Inertia y-0.013Kg.m= Rated Current /,v=5.4A Rated Moment miV=8.9Nm Rated Speed nw = 1! 70rpm Rated Power PN = 09kW and a negative definite fiinction: v(t) = smt) To assure sliding siu"face s=0, where: ,dn d n