Comparison between NEMA 23 closed loop stepper motor and servo motor
Servo motor is respected and talked about by engineers nowadays. It is almost unimaginable to mention motion control without talking about servo motor. Engineers are obsessed with the closed-loop control of servo motor, and indulge in the advantages of high response, high speed and high precision. However, as the saying goes, every inch has its strong points. The servo motor also has the following unavoidable defects
1. Unable to be stationary: due to the closed-loop control, the structure of the servo motor and the characteristics of the motor decide that the servo motor cannot be absolutely stationary when it stops. Under the condition of small load disturbance or good parameter debugging of the servo motor, the servo motor always fluctuates between positive and negative 1 pulse (you can observe the value of encoder position on the servo driver, It fluctuates between plus and minus one all the time. In the case of image processing, this is a factor affecting the accuracy.
2. Overshoot: when changing from high speed to low speed or static, it is inevitable to overshoot for a certain distance and then correct it. When the controller sends a pulse to the servo motor, the servo motor usually goes three pulses instead of one pulse, and then goes back two pulses. This is fatal to those occasions where one pulse is needed and one pulse is needed and overshoot is absolutely not allowed.
3. Complex debugging: there are hundreds of parameters in the servo driver and hundreds of pages of instructions, which makes the novice really afraid; Replacing a brand of servo motor will also give veteran a headache. This also brings a lot of work for after-sales service and maintenance.
4. Low speed creep: at low speed, the servo motor will creep or crawl.
And the NEMA 23 closed loop stepper motor perfectly solves the above problems.
Because the NEMA 23 closed loop stepper motor is not simply equipped with an encoder, it is designed and developed according to the working principle of servo motor system. It uses 32-bit DSP as the main processor to ensure the high response and high speed of the whole system. It can adjust the current of the motor every 25 microseconds. It is equipped with a standard encoder of 10000 pulses / turns. It is also an encoder of metal encoder, which not only ensures the accuracy, but also ensures the high adaptability, stability and reliability to the environment, temperature and vibration, Even better than the servo motor using glass encoder.
First of all, the NEMA 23 closed loop stepper motor is absolutely stationary when it is stationary because it is the body of the motor and the stepper motor.
Secondly, because the NEMA 23 closed loop stepper motor combines the characteristics of stepper motor and servo control mode, it will not overshoot (because the characteristic of stepper motor is that it will not overshoot).
Third, the debugging and use is very simple. It only needs to adjust the position of the three potentiometers of the driver. Not only the equipment manufacturer can use it, but also the equipment user can use it. The requirements for users are very low.
Fourth, the driver uses real sine wave, vector and filter to control the current. The lowest speed can be controlled at 0.2 rpm, and the motor runs very smoothly and stably, which even the servo motor can't do (generally, the servo motor can do 1 RPM in theory, but it can't do 1 rpm in practical application, which is more than 5 RPM).