12.1.1.3 Calculation of the maximum torque M upon positioning and acceleration 12.1.2 Preliminary determination of mechanical gear ratio Calculate the maximum mechanical reduction ratio based on the required maximum speed and maximum rotating speed of the motor. Use the reduction ratio and the minimum revolution unit of the motor to check if the minimal position unit requirement is satisfied; if high position accuracy is required, increase the mechanical reduction ratio (actual maximum speed reduced) or select to use a motor with a higher rotating speed.
12.1.3 12.1.1 Inertia and torque check Convert the load inertia and load torque into the motor shaft by using the mechanical reduction ratio. The converted inertia shall generally be no greater than 5 times the motor's rotor inertia (with response speed requirements). The converted load torque and effective torque shall be no greater than the motor's rated torque. If the above requirements cannot be satisfied, the user may increase the mechanical reduction ratio (actual maximum speed reduced) or select to use a motor of a larger capacity.
12.2 Stop features When pulse trains are used to control the servo motor in the position control mode, there is a difference between the command pulse and the feedback pulse, which is known as hysteretic pulse. Hysteretic pulses are accumulatively calculated in the position deviation counter, and have the following relationship with the pulse frequency, the electronic gear ratio and the position proportional gain [Note] The relationship above is obtained under the condition that the [position feedforward gain] is 0%; if the [position feedforward gain] >0%, the count of hysteretic pulses will be smaller than the result obtained by using the formula above.
12.3 Servo system and calculation method for selection of the position controller model 12.3.1 Command displacement and actual displacement: Commanly S = I, and the command value is equal to the actual value. 12.3.2 CNC maximum command speed: 12.3.3 Maximum speed of the servo system: The actual maximum speed of the machine tool is restricted by the maximum speeds of the CNC and the servo system. 12.3.4 Minimum amount of machine tool movement:
206 Technical Manual for EA190 Series Servo Driver V100 nm Motor speed change during positioning and acceleration (r /min) ta Acceleration/deceleration time (s), if ta ≈3 /KS, take 0.15-0.2s KS Commonly 8s-1- 25s-1 is taken for open-loop gain of the system, and around 20s-1 is generally taken for a machining center ML Load torque (N•m) JM Motor's rotor inertia (kg•m2) JL Motor shaft inertia converted from load inertia (kg•m2) ε Hysteretic pulse (Puls) APR-P Position loop gain f Command pulse frequency (Hz) G Electronic gear ratio (P1-06÷P1-08) S Actual displacement, mm DR Servo frequency multiplication coefficient I Command displacement, mm DD Servo frequency division coefficient δ Minimal unit of CNC, in mm ST Number of scale division units per each revolution of the servo motor CR Command frequency multiplication coefficient Z1 Motor-side gear teeth CD Command frequency division coefficient Z2 Screw-side gear teeth L Screw lead, mm F Command speed, mm/min fmax CNC maximum output frequency, Hz Vmax Maximum allowed speed with load of the servo system, mm/min nmax Maximum allowed rotating speed of the servo motor, rpm α Minimum distance of machine tool movement, mm N Natural number INT( ) Represent rounding INT[ ]min Represent the smallest integer