Stepper Motor Wiring Method And Current Setting

- Oct 09, 2017-

Stepper motor wiring method and curren setting

The stepper motor wiring method is an electromagnetic actuator that converts digital input pulses into rotary or linear incremental motion.Each input a pulse,motor shaft is stepped by a step angle increment.

The total rotation angle of the motor is proportional to the number of input pulses,and the corresponding speed depends on the input pulse frequency.Stepper motor wiring method is one of the key components of mechatronics products,usually used  as positioning control and fixed speed control.

Stepper motor inertia is low,high positioning accuracy,no cumulative error,simple control and so on.Stepper motor wiring method is widely used in mechanical and electrical integration products,such as: CNC machine tools,packaging machinery, computer peripherals,copiers,fax machines.

When select a stepper motor,first make sure that the output power of the stepper motor is greater than the power required for the load.Stepping motor wiring method at selection power stepper motor,first calculate the mechanical system load torque,the motor torque characteristics to meet mechanical load and have a certain margin to ensure its operation.

Stepping motor wiring method in actual work process,the load torque at various frequencies must be within the range of the

Torque-Frequency characteristic curve.Generally speaking,the large maximum static torque Mjmax stepper motor,the load torque

is large.

When select a stepper motor,the step angle should be matched to the mechanical system,so that the pulse equivalent required for the machine can be obtained.Stepping motor wiring method in the process of mechanical transmission,in order to make a smaller pulse equivalent,one can change screw wire lead,the second is to complete through stepper motor micro-step drive.

Stepper motor wiring method segmentation can only change its resolution without its accuracy.The accuracy is determined by the inherent characteristics of the motor.

When select the power stepper motor,the load inertia of the mechanical load and the starting frequency of the machine tool should be estimated,so as to match the inertia frequency characteristics of the stepper motor with a margin,so that the highest continuous operating frequency can meet the machine fast moving needs.

Stepping Motor Wiring Method select stepper motor that needs to be calculated as follows:

(1) Calculate the gear reduction ratio.According to the required pulse equivalent,the gear reduction ratio "i" is calculated as follows: i = (φ.S) / (360.Δ) (1-1) where φ --- step Angle (o / pulse) S --- screw pitch (mm) Δ --- (mm / pulse)

(2) Calculate the inertia of the workbench,screw and gear to the motor shaft inertia Jt.Jt = J1 (1 / i2) (1-2) where Jt --- inertia converted to the motor shaft ( J1, J2 --- gear inertia ( Js- --- screw inertia ( W --- table weight (N) S --- screw pitch (cm)

(3) Calculate the total torque of the motor output M.M = Ma Mf Mt (1-3) Ma = (Jm Jt) .n / T× 1.02 × 10 ˉ 2 (1) where

 Ma --- motor starting acceleration torque (N.m ) Jm、Jt --- motor inertia and load inertia ( n --- motor required speed (r / min) T --- motor speed time (s) Mf = (uWs ) / (2πηi) × 10 ˉ 2 (1-5) Mf --- torque of the rail converted to the motor torque (N.m) u --- friction coefficient η --- transfer efficiency Mt = (Pt.s) / (2πηi) × 10 ˉ 2 (1-6) Mt --- Cutting force converted to motor torque (N.m) Pt --- Maximum cutting force (N)

(4) Load start frequency estimation.The starting frequency of the motor which is controlled by stepper motor wiring method CNC systems has close relationship with load torque and inertia.fq=fq0 1/2(1-7) where the fq---load starting frequency(Hz) fq0 --- 

No-load starting frequency Ml --- Motor output torque (N.m) determined by torque-frequency characteristic at the starting  frequency,if load parameter can not be accurately determined,it can be estimated by fq = 1 / 2fq0.

(5) the highest frequency of operation and calculation of acceleration time.

Stepping motor wiring method,since the output torque of the motor decreases as the frequency increases,the output torque from torque-frequency characteristic at highest frequency,should be able to drive the load and leave sufficient margin.

(6) Load torque and maximum holding torque Mmax.

The load torque can be calculated according to equations (1-5) and (1-6). When the motor is at maximum feed rate, the motor output torque determined by the moment characteristic is greater than the sum of Mf and Mt. Leave margin.

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