Engraving machine stepper motor is an electrical pulse into the angular displacement of the actuator. When a stepper drive pulse signal is received , it will drive the stepping motor to set the direction of rotation of a fixed angle ( referred to as " step angle " ) , which is fixed to the rotational angle of the step by step operation . The number of pulses can be controlled by controlling the amount of angular displacement , so as to achieve accurate positioning ; while the pulse frequency can be controlled by controlling the motor rotation speed and acceleration to achieve speed control purposes . Stepper motor control can be used as a special motor , using its no accumulation of errors ( accuracy of 100% ) , which is widely used in a variety of open-loop control .
Now more commonly used include stepper motor stepper motor response (VR), permanent magnet stepper motor (PM), hybrid stepper motors (HB) and single-phase stepper motor.
Permanent magnet stepper motor is generally a two-phase , small torque and volume , step angle of 7.5 degrees , or 15 degrees ;
The reaction is generally a three-phase stepping motor can achieve high torque output , step angle of 1.5 degrees , but the noise and vibration are great. Reaction stepping motor rotor magnetic soft magnetic materials, multi-phase field windings on the stator , the use of magnetic permeability changes generated torque.
Hybrid stepper motor is a mix of permanent and reactive advantages. It is divided into two phases and five phase: two -phase step angle of 1.8 degrees while the five -phase stepper angle of 0.72 degrees. This stepper motor applications most widely used, but also in this segment of the selected drive stepper motor program .
Some of the basic parameters of the stepper motor :
Inherent motor step angle :
Each of which represents the control system sends a pulse signal, the motor rotation angle. Motor factory gives a step angle value , such as 86BYG250A motor gives a value of 0.9 ° / 1.8 ° ( half step when said work is 0.9 °, while working as a full step 1.8 °), this step angle You can call it " inherent motor step angle ," it is not necessarily true motor step angle when the actual work , the real step angle and driver related.
Stepper motor phases :
Is the number of coils inside the motor group , currently used for two -phase , three-phase , four-phase , five-phase stepper motor. Motor phase number is different, the step angle is different, generally two-phase step motor angle of 0.9 ° / 1.8 °, three-phase is 0.75 ° / 1.5 °, five- phase is 0.36 ° / 0.72 °. In the absence of sub-drive , the user to select a different number of phases depends mainly on the stepper motor step angle to meet their requirements . If you use a sub-drive , then ' phases ' will become meaningless , users only need to change the number of segments on the drive , you can change the step angle .
Holding torque (HOLDING TORQUE):
Refers to the stepper motor power but no rotation , the stator locked rotor torque . It is one of the most important parameters of the stepper motor , usually a stepper motor at low speeds close to the torque holding torque . As the stepper motor output torque with speed and continuous decay , the output power with increasing speed of change, so holding torque has become one of the most important parameters to measure the stepper motor. For example, when people say 2N.m stepper motor , in the absence of special note is to keep the torque 2N.m stepper motor .
Refers to the case of a stepper motor is not energized , the stator locked rotor torque . DETENT TORQUE translation in the country there is no uniform way , so that we can easily misunderstand ; due to the reaction of the rotor permanent magnet material is not stepping motor , so it does not DETENT TORQUE.
Stepper motor characteristics:
1 . General accuracy of the stepper motor step angle of 3-5 % , and does not accumulate.
2 . Stepper motor appearance maximum temperature allowed .
First, make a stepper motor temperature demagnetization magnetic motor , resulting in the loss of torque down even further , so the maximum temperature of the motor should be allowed depending on the appearance of magnetic motor demagnetization points ; Generally speaking, the magnetic demagnetization points are more than 130 degrees Celsius , and some even as high as 200 degrees Celsius , so the stepper motor surface temperature at 80-90 degrees Celsius completely normal.
3 . Stepper motor torque will increase with the speed of the decline .
When the stepping motor rotates , the inductance of the motor windings of each phase will form a counter electromotive force ; the higher the frequency, the greater the back EMF . In its role, the motor with frequency ( or speed ) increases the phase current is reduced , resulting in decreased torque .
4 . Low-speed stepper motor can operate normally , but if more than a certain speed will not start , accompanied by howling.
Stepper motor has a technical parameter : load starting frequency , ie stepper motor under no-load conditions to start the normal pulse frequency , if the pulse frequency is higher than this value, the motor does not start properly , you may lose steps or stall . Under a load , the starting frequency should be lower . If you want the motor to achieve high-speed rotation , the pulse frequency should speed up the process , which starts at lower frequencies , and then rise to the hope that at a certain acceleration frequency ( motor speed rise from low speed ) .
Stepper motor with its remarkable features in the era of digital manufacturing plays a significant purpose. Along with improving the different development of digital technology and the technology itself, stepper motor , stepper motors will be applied in more fields .