tailieunhanh - Adjusting Servo Drive Compensation

A drive sizing makes sure that the drive has enough torque to satisfy the load requirements to overcome friction losses, provide sufficient load thrust, and provide enough acceleration torque for the type of acceleration required. Once the drive-sizing requirement is satisfied, the servo drive stability must be addressed. Stabilizing the servo drive is a matter of adjusting the servo compensation. All industrial servo drives require some form of compensation often referred to as proportional, integral, and differential (PID). The process of applying this compensation is known as servo equalization or servo synthesis. In general, commercial industrial servo drives use proportional. | 14 Adjusting Servo Drive Compensation MOTOR AND CURRENT LOOP A drive sizing makes sure that the drive has enough torque to satisfy the load requirements to overcome friction losses provide sufficient load thrust and provide enough acceleration torque for the type of acceleration required. Once the drive-sizing requirement is satisfied the servo drive stability must be addressed. Stabilizing the servo drive is a matter of adjusting the servo compensation. All industrial servo drives require some form of compensation often referred to as proportional integral and differential PID . The process of applying this compensation is known as servo equalization or servo synthesis. In general commercial industrial servo drives use proportional plus integral compensation PI . It is the purpose of this discussion to analyze and describe the procedure for implementing PI servo compensation. The block diagram of Figure 1 represents DC and brushless DC motors. All commercial industrial servo drives make use of a current loop for torque regulation requirements. Figure 1 includes the current loop for the servo drive with PI compensation. Since the block diagram of Figure 1 is Copyright 2003 by Marcel Dekker Inc. All Rights Reserved Fig. 1 Motor and current loop block diagram. not solvable block diagram algebra separates the servo loops to an inner and outer servo loop of Figure 2. For this discussion a worst-case condition for a large industrial servo axis will be used. The following parameters are assumed from this industrial machine servo application Motor Kollmorgen motor M607B Machine slide weight 50 000 lbs Ball screw Length 70 in. Diameter 3 in. Lead in. revolution Pulley ratio JT total inertia at the motor te electrical time constant second 50 rad sec t1 te Ke motor voltage constant volt-sec radian Kt motor torque constant . amp Kg amplifier gain 20 volts volt Kie current loop feedback constant 3 volts 40A volt amp