What is a servo motor?
Servo motors are electric motors that are designed specially for high dynamics. Servo motors by ESR distinguish themselves by a compact design with high power density and a high degree of protection (up to IP 65). They come as AC servo motors (brushless) or DC servo motors (with brushes for the commutation). The high power density is achieved by permanent magnets made of neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), or ferrite material. The servo motor is equipped with a position sensor which provides the controller with position and speed information.
What kind of motor position sensor can be used?
As a standard, the AC servo motors are equipped with resolvers. In combination with the digital servo drives sincos encoders (absolute encoder, single-turn or multi-turn) and high-resolution incremental encoders may be used as well, in case higher accuracy or dynamics is required.
The DC servo motors can be equipped with tachogenerators and/or incremental encoders.
How to choose the appropriate servo motor?
For dimensioning the motor the following data are important: the mass of the parts to be moved, the cycle time of the application, and the friction torque. With these data the rated and peak torque (maximum acceleration or deceleration) and the rated speed can be calculated. If required, gears are used to match the moment of inertia of the motor to the moment of inertia of the application.
You can find technical specifications on ESR's servo motors at Products/Servo motors.
As a specialist for servo drive technology we offer a comprehensive support at choosing the right servo drive system, from drive system configuration in cooperation with users to solutions for special applications (see Support).
What is a servo drive?
The servo drive (also called "servo amplifier", "servo inverter", "servo controller", or just "controller") controls the current of the motor phases in order to supply the servo motor with exactly the current required for the desired torque and the desired speed. The essential parts of a servo drive are the power section and the control loops.
The power section consists of a mains rectifier, a DC-bus, and a power circuit which supplies the individual motor phases with current.
The control loops (analog or digital) drive the power circuit and by constantly comparing setpoint with actual values ensure that the motor keeps exactly to the desired motions even under varying load.
In addition, ESR servo drives offer a broad spectrum of functionality (see Applications).
How to choose the appropriate servo drive?
The servo drive has to supply the motor with the required current (rated current at continuous operation, peak current) and match the terminal voltage of the motor (125 V, 320 V, or 560 V). Also the intended purpose is important for the choice of the right drive:
Is the servo drive going to be used in velocity mode in a multi-axis application with a higher-level controller (e. g. CNC)? Then an analog servo drive may be sufficient.
Or should the drive be equipped with more functionality (e. g. for positioning control or axis synchronization) or a fieldbus (e. g. Interbus, CANopen, or Profibus-DP) for communication with the higher-level controller? In this case a digital servo drive has to be used.
We help you choose the right servo drive system matching your application and offer our support regarding drive system configuration (see Support).
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