tailieunhanh - Drive Sizing Considerations

INTRODUCTION In the application of industrial servo drives to machines it is important that the drive be large enough to meet all the load torque requirements and be stable. It is necessary to make sure that the servo drive torque rating is large enough to meet the load thrust and acceleration requirements plus the machine friction losses; an organized method to accomplish this is referred to as ‘‘sizing the drive.’’ There are many drive-sizing software programs available from commercial servo drive suppliers. It is of critical importance that machine designers size the servo drive in an organized engineering manner. Either manual. | 13 Drive Sizing Considerations INTRODUCTION In the application of industrial servo drives to machines it is important that the drive be large enough to meet all the load torque requirements and be stable. It is necessary to make sure that the servo drive torque rating is large enough to meet the load thrust and acceleration requirements plus the machine friction losses an organized method to accomplish this is referred to as sizing the drive. There are many drive-sizing software programs available from commercial servo drive suppliers. It is of critical importance that machine designers size the servo drive in an organized engineering manner. Either manual or computer software sizing must be used to avoid an unacceptable servo-drive performance. It is also a requirement that the software drivesizing programs be documented and interactive with the user. Machine design engineers may not have a feedback control background thus it is important that the programs have complete documentation sometimes referred to as remark statements . To be of value to the user the software programs should be interactive with enough description of what is happening during the drive-sizing process. The criteria of the drive sizing are different for hydraulic and electric drive sizing. Hydraulic servo drives usually have more than ample torque to Copyright 2003 by Marcel Dekker Inc. All Rights Reserved meet the load requirements. However the hydraulic fluid has compressibility which is like a spring inside the servo loop and can cause a minor loop instability. This hydraulic spring is represented as a hydraulic resonance. Any hydraulic servo drive with a large volume of hydraulic oil compressed between the actuator and the servo valve has a potential for an unstable minor loop servo drive. Hydraulic servo valve drives that use long-travel piston actuators have a great potential for servo instability. Likewise hydraulic servo pump drives with large volumes of hydraulic fluid between .