How to choose stepper motor
Stepper motor has step Angle (related to the number of phases), static torque, and current three elements. Once the three elements are determined, the model of the stepper motor is determined.
1. Choice of step Angle
The step Angle of the motor depends on the requirements of load accuracy, and the minimum resolution (equivalent) of the load is converted to the motor shaft, and how many angles (including deceleration) should be taken by each equivalent motor. The motor step Angle should be equal to or less than this Angle. At present, the step Angle of the stepper motor on the market is generally 0.36 degrees /0.72 degrees (five-phase motor), 0.9 degrees /1.8 degrees (two and four-phase motors), 1.5 degrees /3 degrees (three-phase motors) and so on.
2. the choice of static moment
The dynamic torque of the stepper motor is difficult to determine all of a sudden, and we often determine the static torque of the motor first. The choice of static moment is based on the load of the motor, and the load can be divided into inertia load and friction load. A single inertial load and a single friction load do not exist. When starting directly (generally at low speed), the two loads should be considered, the inertial load should be mainly considered when accelerating the start, and the friction load should be considered when running at constant speed. Under normal circumstances, the static moment should be 2-3 times the friction load, and once the static moment is selected, the frame and length of the motor can be determined (which size).
3. the choice of current
Static moment of the same motor, due to different current parameters, its operating characteristics are very different, according to the moment frequency characteristic curve, judge the current of the motor (refer to the drive power supply, and drive voltage).
4. torque and power conversion
Stepper motor is generally used in a wide range of speed regulation, its power is changed, generally only measured by torque, torque and power conversion is as follows: P= Ω· Mω =2π·n/60 P=2πnM/60, where P is the power unit of watts,Ω is the angular velocity per second, in radians,n is the speed per minute,M is the torque unit of Newton · meters P=2πfM/400(half step work), where f is the number of pulses per second (PPS).
