The role of four control modes of Invidon servo motor
In the CNC machine, the operation of the Inverter servo motor drive can be divided into open loop control and closed loop control according to its structure. If detailed classification, open-loop control can be divided into ordinary type and reaction compensation type, and closed-loop (semi-closed loop) control can also be divided into ordinary type and reaction compensation type. 1. Closed loop control Because the accuracy of the open loop control is not very satisfactory for the machine tool, in order to improve the control precision of the Invitro servo drive, the fundamental method is to use the closed loop control method. That is to say, not only the predecessor control channel, but also the reaction channel for detecting the output, the command signal is compared with the reaction signal, and the deviation signal is formed to form a closed-loop control system controlled by the deviation. 2. Reaction-compensated open-loop control The accuracy of the open-loop system is low. This is because the step size error, start-stop error, and mechanical system errors of the INVT servo drive directly affect the positioning accuracy. The compensation type should be selected for improvement. This system has the advantages of both open-loop and closed-loop, namely, the stability of the open loop and the precision and accuracy of the closed loop. The system will not oscillate due to the resonant frequency, 匍匐, and misalignment of the machine tool. The reaction-compensated open-loop control does not require clearance compensation and pitch compensation. 3. Reaction-compensated semi-closed-loop control. The servo motor driver control compensation principle is the same as the open-loop compensation system. The two sets of independent measurement systems consisting of a resolver and an inductive synchronizer are Work in the method of discrimination. The shortcoming of this system is that the cost is high. It is necessary to use two sets of detection systems. The advantage is that it is easier to adjust than the full-closed system and has good stability. It is suitable for the feed drive of high-precision large-scale CNC machine tools. 4. Semi-closed loop control
Regarding the closed-loop control system, reasonable planning can be obtained, to the firm stability and high precision, but the direct measurement of the orientation signal of the workbench requires the use of gratings and magnetics. Equipment such as ruler or linear induction synchronizer, and azimuth detection equipment with high maintenance requirements. By measuring the angular displacement of the drive shaft or the screw, the equivalent reaction signal of the azimuth output can be obtained indirectly. Because the error caused by this part of the transmission can not be included in the transmission chain between the rotating shaft and the workbench in the closed-loop system, the error caused by this part of the transmission cannot be actively compensated by the closed-loop system, so it is called the equivalent reaction signal. The closed-loop control system is a semi-closed-loop servo driver. This control method is called semi-closed loop control method.