The differences between a servo motor and a stepper motor lies in the torque, price, and performance – and of course in the underlying technology. In a stepper motor, the rotor is driven by an electrical field in the stator that rotates in steps. Depending on the predetermined step angle of the electromagnetic field, the motor moves more precisely. However, if the motor becomes overloaded, the rotor can no longer follow the torque.
The resulting step loss and incorrect positioning of the rotor must then be prevented by what is known as a position encoder. The motor usually ends up being oversized to meet the torque requirements at all times and to ensure that no steps are lost. The oversized motor requires a lot of energy. Which is why stepper motors are particularly effective when working in a low speed range.
Due to their holding torque in the idle position, they are also suitable for holding loads. However, they must be permanently supplied with power – even when stationary. In everyday life, stepper motors have a wide range of applications. They are used in automatic assembly machines in industry, for controlling camera lenses, for positioning control elements in combustion engines, in robotics, and in 3D printers. But if you want to perform precise work in higher speed ranges, a servo motor is the better choice.
An electric motor is also equipped with a rotor position sensor for positioning. The electromagnetic rotor rotates in the magnetic stator. The movement of the motor is controlled by a servo controller. Together with the servo motor, this forms a servo drive. Because of the control characteristics of the position, speed and power supply, drives of this type are often used in industrial systems.
They are also used in tools and industrial robots – and even in remote-controlled model vehicles, aircraft and ships. Compared to a stepper motor, the purchase price for a servo motor is rather high.
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