Student: Cheng-Yi Chiang Adviser: Ming-Shyan Wang Date : 31th-Dec-2008 A Novel Motor Drive Design for Incremental Motion System via Sliding-Mode Control Method IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 52, NO. 2, APRIL 2005 Chiu-Keng Lai and Kuo-Kai Shyu, Member, IEEE Student: Cheng-Yi Chiang Adviser: Ming-Shyan Wang Date : 31th-Dec-2008

Outline Abstract INTRODUCTION FIELD-ORIENTED PMSM INCREMENTAL MOTION CONTROL OF PMSM A. Velocity Control Mode B. Position Control Mode C. Velocity Control Mode D. Position Control Mode SIMULATION RESULTS EXPERIMENTAL SETUP AND RESULTS A. Experimental System Setup B. Experimental Results CONCLUSION REFERENCES

Abstract This paper proposes a particular motor position control drive design via a novel sliding-mode controller. The newly designed controller is especially suitable for the motor incremental motion control which is specified by a trapezoidal velocity profile. The novel sliding-mode controller is designed in accordance with the trapezoidal velocity profile to guarantee the desired performance. A motor control system associated PC-based incremental motion controller with permanent-magnet synchronous motor is built to verify the control effect. The validity of the novel incremental motion controller with sliding-mode control method is demonstrated by simulation and experimental results.

INTRODUCTION The control of motors used in high-performance servo drives requires the prescribed torque accuracy, velocity, and/or position for all operating conditions being achieved. To obtain the desired performance, a precise system model is needed. It is difficult to construct because of the inherent nonlinearity of friction and dead zone, the parameter variations due to temperature, the uncertain external disturbances, and so on. PI-type control methods are not robust enough to accommodate the variations of external disturbances, parameters, and perturbations during operation

INTRODUCTION Variable-structure control (VSC) or sliding-mode control (SMC) has been known as a very effective way to control a system because it possesses many advantages. such as insensitivity to parameter variations, external disturbance rejection, and fast dynamic responses. VSC has been widely used in the position and velocity control of dc and ac motor drives. The system dynamics of a VSC system can be divided into two phases: the reaching one and the sliding one. The robustness of a VSC system resides in its sliding phase, rather the reaching phase.

INTRODUCTION This paper proposes a multisegment sliding-mode- control-method-based motion control drive design in accordance with a trapezoidal velocity profile. It also shows that the reaching phase existing in the conventional VSC does not exist in the designed multisegment sliding-mode controller. The robustness of the controlled system can be assured from start to finish.

FIELD-ORIENTED PMSM , the d, q-axes stator voltages. , the d, q-axes stator currents. , the d, q-axes inductance. , the d, q-axes stator flux linkages. , the stator resistance and inverter frequency. the equivalent d-axes magentizing current. the d-axis mutual inductance. (1) (2) (3) (4)

FIELD-ORIENTED PMSM the pole number of the motor. the rotor velocity. (5) the pole number of the motor. the rotor velocity. the rotor angular displacement. the moment of inertia. the damping coefficient. the external load. The inverter frequency is related to the rotor velocity as (6) (7)

FIELD-ORIENTED PMSM Since the magnetic flux generated from the permanent magnetic rotor is fixed in relation to the rotor shaft position. The flux position in the coordinates can be determined by the shaft position sensor.

FIELD-ORIENTED PMSM The PMSM used in this drive system is a threephase four-pole 750-W 3.47-A 3000-r/min type. Fig.1. (a) System configuration of fiele-oriented synchronous motor.

FIELD-ORIENTED PMSM Fig.1. (b) Simplified control system block diagram. (8) (9) is the inverter torque command which is proportional to the –axis current, .

INCREMENTAL MOTION CONTROL OF PMSM The rotor dynamics and the torque equation of PMSM given in (6)-(8) are rewritten as follows: (10)

INCREMENTAL MOTION CONTROL OF PMSM The incremental motion control is to move an object at rest at time to a fixed desired position at time , and then stop it. The control process is subjected to the desired velocity and acceleration. Therefore, the incremental motion control is performed under velocity control in obedience to a desired velocity profile, whereas stopping is done by position control mode.

INCREMENTAL MOTION CONTROL OF PMSM One first has to select a velocity profile which rapidly changes the load position in discrete step. The velocity profile should satisfy the motion constraints of the system. The velocity and acceleration limitations are generally taken into consideration for the determination of velocity profile. To satisfy the velocity and acceleration limitations, a trapezoidal velocity profile is usually used. The object here is to design a multisegment sliding mode controller according to the trapezoidal velocity profile

INCREMENTAL MOTION CONTROL OF PMSM Fig.2. Trapezoidal velocity profile for incremental motion control.

INCREMENTAL MOTION CONTROL OF PMSM With a specified rotor position , which is assumed to be a constant within the control process, one first defines the position error and its derivative as Combining (11) with (6) and (7), one obtains Note that (12) and (13) hold because the specified position is a constant. (11) (12) (13)

INCREMENTAL MOTION CONTROL OF PMSM According to the error dynamical equations (12) and (13), a multisegment SMC is proposed to drive the motor from initial position to the specified position according to the trapezoidal velocity profile given in Fig. 2. The multisegment SMC is composed of two modes, the velocity control mode and the position control mode. The velocity control mode is used to drive the rotor to the desired position and the position control mode is used to hold the rotor at the desired position

A. Velocity Control Mode 1) Acceleration segment : is the initial position error. To check the motor acceleration on Thus, the motor dynamics on the acceleration segment (14) have the desired constant acceleration . (14)

A. Velocity Control Mode 2) Run segment 3)Deceleration segment (15) (16)

B. Position Control Mode In the position control mode, the following position control segment is proposed: where is a positive constant. Lemma [6]–[8]: If a switching surface of the controlled system satisfies the following sliding condition: Where and are parameters to be designed in accordance with the corresponding sliding segment, and has been defined in (8). (17) (18) (19)

C.Velocity Control Mode First, the acceleration segment is considered. The parameters and in (19) will be designed to satisfy the sliding condition of the acceleration segment where , and is the sign function. (20) (21) (22) (23)

C.Velocity Control Mode where and where and (23) (24) (25) (26) (27) (28)

D.Position Control Mode Where and (29) (30) (31) (32)

Position Control Mode Fig. 3. Multisegment SMC-based incremental motion control for PMSM system

SIMULATION RESULTS Fig. 4. Simulated results of multisegment sliding-mode motion control. (a) Velocity responses. (b) Position responses. (c) Control output.

SIMULATION RESULTS Fig. 5. Trajectories of four switching functions of multisegment sliding- mode controller.

SIMULATION RESULTS Fig. 6. Simulated results of conventional sliding-mode motion control. (a) Velocity responses. (b) Position responses. (c) Control output.

SIMULATION RESULTS Fig. 7. Simulated results with external load 2 N‧m. (a) Velocity responses. (b) Position responses. (c) Control output.

SIMULATION RESULTS Fig. 8. Simulated results with external load 2 N‧m and

Experimental System Setup Fig. 9. Pentium-800–based PMSM incremental motion control system.

Fig. 10. (a) Experimental results controlled by multisegment SMC controller. From top to bottom: velocity responses, position responses, control output, and phase-A current.

Fig. 10. (b) Experimental trajectories of four segments controlled by multisegment SMC controller.

Fig. 11. Experimental results controlled by conventional SMC controller. From top to bottom: velocity responses, position responses, control output, and phase-A current.

Fig. 12. Experimental results with generator load. From top to bottom: velocity responses, position responses, and phase-A current.

CONCLUSION A particular incremental motion control using novel VSC strategy for a PMSM is presented. It has been shown that the multisegment SMC has the ability to control the motor system with a constant acceleration and deceleration rate to match the trapezoidal velocity profile of the incremental motion. Furthermore, the proposed system is robust to the external time-varying load. Both simulations and experimental results confirm the validity.

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