Servo Motor and Stepper Motor – What’s the difference?
Understand the difference between Servo Motor and Stepper Motor
This is a step by step tutorial for our customer to understand, not only to a structural level, but in terms of functions, the pros and cons of stepper motro and servo motor.
How Servo and Stepping Motors work differently?
Stepping motor is also referred to as pulse motor or stepping motor. It is in essence an open-loop system, or say, there is no inbuilt encoder feedback from the motor to its drive.
By mentioned drive or motor driver, it is a inner part or say device that drives and controls the motor. The stepping motor responds to pulse signals generated by PLC which then are inputed to motor driver and as a result the rotation-axis of motor would rotate and thus embodies a full working cycle of stepping motor.
The angle to which the motor rotates is fixed. Supposing the 1 pulse stands for 0.72 degress, to rotate 90 degrees 150 pulses. The speed of a stepping motors is proportional to the frequency of pulse. The higher the frequency is, the faster the stepping motor works.
Servo motor, however, works in a manner called “Closed loop system”. In difference with the stepping motor, the servo motor is incoporated with an inbult encoder that gives current feedback to servo driver. Pulses generated from PLC is transferred to servo driver with directio signal which in turn gives supply to motor and leads to that the motor starts rotating. The motor would also inturn gives runing feeback to servo drive with the encoder cable which we can take in PLC by control cables.
Sounds complicate? Here are the brief pros and cons for you easy understanding
Stepping motor is usually used as an economic option due to it relative lower cost in comparison with servo motor, however, this also signifies that the stepping motor is outstripped by servo motor in terms of functions and efficiency. Yet this does not necessarily mean that servo motor is always the better option than steppper motor. Generally the servo motor is used to meed high standard specifications or specific need in machine construction and design, but when it comes to specific parts where no such a high standard is required the used of servo motor would be a redundancy and a less “lean” option than stepper motor. As following a brief comparison between stepper and servo motor in terms of various specifications.
|#||Specifications||Stepper Motor||Servo Motor|
|01||System function||Open-loop system (no position feedback or encoder)||Closed-loop system (position feedback or encoder present)|
|02||What is the cost of stepper & servo motors?||Cost-effective||Very expensive|
|03||How fast can stepper & servo motors turn?||Low Speed (1500 RPM maximum)||High Speed (5000 RPM maximum)|
|04||Torque/ speed control odf||No torque-control or speed-control mode||torque-control or speed-control mode|
|05||Are stepper & servo motors AC or DC?||DC current use||AC current use|
|06||Torque of stepper & servo motor||High torque in low speed||High torque in high speed|
|07||Requirement||No tuning required||tuning required|
|08||Consuming power||Consumes less power||Consumes more power|
|09||Function||Simple and easier for commissioning||Complex for commissioning|
|10||Size||Maximum 750W motor size available||50W to 15KW motor size available|
Servo Motor used for Packaging Machines
Servo motors are widely applied in constructing packaging machines due to its precision, excellent function and capability of being used in complex context. Almost all the machines among ÉLITER´s catalogue are incorporated with servos. This complies with our commitment of quality focused spirit. We strive to provide our customer with high standard machine of reliable, efficient, highly precision and fully trustworthy machines.