BECKHOFF DK9222-0610-0027 User Manual

I/O

Application Note DK9222-0610-0027

Motion

Keywords

Buffer capacitor
Brake chopper
Fieldbus
Drive
Stepper
DC motor
Output stage
DC link
Overload
Recovery
EtherCAT
K-Bus
Bus Terminal
PLC

Overvoltage protection and voltage stabilization for
Motion Control terminals

This application example describes how Motion Control applications with the output stages for servo, DC

and stepper motors by Beckhoff are optimized by the utilization of buffer capacitors. The buffer capacitor

terminals EL9570 for EtherCAT and KL9570 for K-Bus stabilize the voltage supply by absorbing the fed back

energy and dumping the energy that the buffer capacitor cannot protect against into an external braking

resistor. The buffer capacitor terminal protects the DC power supply and other motor terminals that may

be sharing the same DC power source. The buffer capacitor terminal extends the area of application for

Beckhoff Motion Control terminals to also include applications with short start/stop ramp times and large

inertia. Additional installation space in control cabinets is saved due to the solution’s compact design as a

double-sized standard terminal block.

Electrical drives

Variable-speed electrical drives are used in practically all industrial sectors. They are preferred for the following reasons:

– Good system efficiency

– Good or very good static and dynamic control characteristics

– Communication with higher-level controllers is possible

– Market prices are in line with user expectations.

Electrical drives are also influenced by the control electronics. New servo drives make complete solutions that are compact

and energy-saving possible. These exhibit dynamic control behavior, good torque stability, and control capability down to zero

speed.

For application notes see disclaimer on the last page

Beckhoff

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I/O

Overview of Motion Control terminals

EtherCAT Terminals Bus Terminals

Servomotors

EL7201

50 V DC, 4 A

–

DC motors

Stepper motors

EL7332

24 V DC, 1 A

EL7342

50 V DC, 3.5 A

EL7031

24 V DC, 1.5 A

EL7041

50 V DC, 5 A

KL2532

24 V DC, 1 A

KL2552

50 V DC, 5 A

KL2531

24 V DC, 1.5 A

KL2541

50 V DC, 5 A

Application Note DK9222-0610-0027

Motion

Servo motors are suitable drives for position control applications. They combine motor, speed and angular position measuring

systems. For cost-sensitive applications with low dynamics, stepper motors may be used as an alternative. In the lower capacity

range, DC motors offer good control ability with low costs. The suitability of a drive is judged on the basis of the torque

produced and the dynamics.

Motion Control in a very compact form factor

The modular I/O system from Beckhoff also encompasses Motion Control in an exceptionally compact form factor. Motors are

driven directly from the PLC with output stages for servo, stepper and DC motors. To have an output stage means that the

motor amplifier is built right into the motor terminal. Whether using an EtherCAT or a Bus Terminal, these I/O devices with

a built in drive can be integrated into any control environment using Beckhoff Bus Couplers. The TwinCAT System Manager

reduces familiarization efforts to a minimum, since TwinCAT enables equal treatment of all motors on the software side. The

interfaces are almost identical, and parameterization is quite straightforward.

Fig. 1 Overview of the Motion Control terminals

DC, servo and stepper motors (principle of operation)

The principles of operation for DC motors and stepper motors are fundamentally different. DC motors generate a torque and a

rotary motion when a voltage is applied. Stepper motors only generate a torque. A prerequisite for the rotary motor motion is

For application notes see disclaimer on the last page

commutation of the current, i.e. inversion of the direction of current flow in the electromagnetic coil during a motor rotation.

DC motors with brushes are self-commutating. Stepper motors cannot commutate independently. Servo motors do not differ

from the aforementioned types of motors in their physical operating principle, but rather in the way they are controlled: they

are operated in conjunction with position feedback in a closed control loop.

Beckhoff

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