Closed loop stepper motor Vs Servo

Closed-loop stepper motors are stepper motors with high-precision encoders and servo control algorithms to achieve torque, speed, and position loops.

Is a closed-loop stepper a servo?

The closed-loop stepper motor is a stepper motor, it has all the functional characteristics of a stepper motor. The biggest difference between stepper motors and servo motors is that stepper motors are open-loop control and servo motors are closed-loop control.

Closed-loop Stepper Motor and Servo Motor difference

1. closed-loop stepper motor body is a stepper motor, at a standstill is stationary. The Servo motor in the stop can not be stationary, in the case of small load disturbance or servo motor parameters are well tuned, the servo motor always fluctuates between positive and negative 1 pulse, in actual use can be properly adjusted motor rigidity to enhance its locking torque and performance.
2. closed-loop stepper motor combines the characteristics of the stepper motor and servo control method, so it will not overshoot (because the characteristics of the stepper motor are not overshot).
   Overshoot is common when a servo motor is turned from high speed to low speed or stationary. When the controller sends a pulse to the servo motor, the servo motor often does not go one pulse, but three pulses, and then back 2 pulses. This is not allowed for those scenarios with strict environmental requirements.

3. Closed-loop stepper motor commissioning and use are very simple, only need to adjust the position of the driver’s 3 potentiometers, which not only equipment manufacturers can use, but also equipment users can use, the user’s requirements are extremely low. Servo motor parameters are more difficult to debug and require experienced engineers to debug.
4. closed-loop stepper motor using a true sine wave, vector, and filtering way to control the current, the lowest speed can be controlled at 0.2 rpm, and the motor runs very smoothly and steadily, which even servo motors can not do (general servo motors can do 1 rpm in theory, the actual application is unable to do 1 rpm, roughly above 5 rpm).
5. Relatively speaking, the accuracy of servo motors is higher than that of closed-loop stepper motors.
6. The cost, to achieve the same function in the case of a servo motor price is greater than the same power closed-loop stepper motor, in the cost of the stepper motor is an advantage.

A Nema24 2 Phase Closed-Loop Servo Motor is a type of electric motor that is specifically designed for use in closed-loop control systems, which means that the motor is controlled by a feedback system that ensures it stays on track and performs according to the desired specifications. The L88mm version of this motor has a length of 88mm, and a rated current of 5A, and a rated torque of 3N.m.

The HSS60 6A Hybrid Step-servo Driver is a type of motor driver that is used to control a Nema24 2 Phase Closed-Loop Servo Motor. It is a hybrid driver, which means it combines the features of both a stepper motor driver and a servo motor driver. It has a rated current of 6A and is compatible with 24-50V voltage inputs.

The Nema24 2 Phase Closed-Loop Servo Motor, HSS60 6A Hybrid Step-servo Driver, and CNC controller kit is a package that includes all of the components needed to control a CNC machine using a closed-loop servo system. It is likely used in applications that require precise control and high performance, such as in the manufacturing or robotics industries.

Closed-loop stepper motor and servo motor product performance differences

1. Speed

Stepper motors with closed-loop control can achieve high-speed operation, a speed almost comparable to servo motors, but also retains the characteristics of the traditional stepper motor’s low speed. Servo motor at high speed can be its performance, in high speed to low speed or stationary, there will be an overshoot phenomenon.

2. Moment frequency characteristics

Closed-loop stepper motor speeds faster the torque is smaller, servo motor in rated speed torque constant.

3. Overload capability

Closed-loop stepper motor has a small (such as 1.5 times) short-time overload output capability, which improves the dynamic response of the stepper motor. The Servo motor is generally 3 times overloaded.

4. Commissioning difficulty

Closed-loop stepper motor commissioning and use are very simple, only needs to adjust the position of a few potentiometers of the driver. Servo motors have hundreds of parameters, debugging complex, often requiring experienced engineers to debug.

5. Noise, heat, vibration

Closed-loop stepper motor and servo motor in the application environment is not particularly rigorous, noise, heat, and vibration is almost not much different, but the servo motor or slightly superior.

6. Working mode

Closed-loop stepper motors work in position mode and speed mode (integrated stepper motors support a variety of remote point of return mode), and servo motors support position mode, speed mode, and torque mode.

7. Precision

Closed-loop stepper motors increase the accuracy of closed-loop control has improved a lot, but relatively speaking, it is still lower than the accuracy of servo motors.

8. Cost and price

Closed-loop stepper motor the cost of the stepper motor is an advantage, to achieve the same function in the case of a servo motor price is greater than the same power of the closed-loop stepper motor, the servo motor’s high response, and high speed and the advantages of high precision determines the high price of the product, which is inevitable.

To sum up, servo motors are used for high precision and high speed in order to give full play to their due speed and accuracy advantages, but in the application environment, the not very strict closed-loop stepper motor is not bad.