Comparison of Stepper Motor and Servo Motor

There is no absolute answer to which is better between stepper motor and servo motor. The most suitable one is the best! The following is an analysis of the advantages, disadvantages and performance characteristics of stepper motors and servo motors:

Stepper motor is a kind of induction motor. Its working principle is to use electronic circuit to turn direct current into time-sharing power supply, and multi-phase sequence control current. Use this current to supply power to stepper motor, so that stepper motor can work normally. The driver is a time-sharing power supply for the stepper motor, a multi-phase sequence controller.

Advantages of stepper motors:
1. The angle of motor rotation is proportional to the number of pulses;

2. When the motor stops, it has the maximum torque (when the winding is excited);

3. Since the accuracy of each step is 3% to 5%, and the error of one step will not be accumulated to the next step, it has better position accuracy and motion repeatability;

4. Excellent start-stop and reverse response;

5. Since there is no brush, the reliability is high, so the life of the motor only depends on the life of the bearing;

6. The response of the motor is only determined by the digital input pulse, so open-loop control can be used, which makes the structure of the motor relatively simple and control costs;

7. Only by directly connecting the load to the shaft of the motor, it can also rotate synchronously at a very low speed;

8. Since the speed is proportional to the pulse frequency, it has a relatively wide speed range.

shortcomings:

1. If the control is improper, it is easy to produce resonance;

2. It is difficult to run to a higher speed;

3. It is difficult to obtain a large torque;

4. There is no advantage in volume and weight, and the energy utilization rate is low;

5. When the load is exceeded, the synchronization will be destroyed, and vibration and noise will be emitted when working at high speed.

Servo motor refers to an engine that controls the operation of mechanical components in a servo system, and is an auxiliary motor indirect speed change device.

The servo motor can control the speed and position accuracy very accurately and can convert the voltage signal into torque and speed to drive the control object. The rotor speed of the servo motor is controlled by the input signal and can respond quickly. In the automatic control system, it is used as an executive element, and has the characteristics of small electromechanical time constant, high linearity, starting voltage, etc., which can convert the received electrical signal. Converted to angular displacement or angular velocity output on the motor shaft. It is divided into two categories: DC and AC servo motors. Its main feature is that when the signal voltage is zero, there is no rotation phenomenon, and the speed decreases uniformly with the increase of torque.

Servo motor advantages:
1. There are no brushes and commutators, so the work is reliable and the maintenance and maintenance requirements are low.

2. It is more convenient for stator winding to dissipate heat.

3. The inertia is small, which is easy to improve the rapidity of the system.

4. It is suitable for high-speed and high-torque working conditions.

shortcomings:

1. The servo must be adjusted according to the needs of the load;

2. The brushes will be consumed and need maintenance for a relatively long cycle time;

3. Price is higher than stepper motor.