© ebm-papst

Speedy inte­gra­tion thanks to intel­li­gent networking

EtherCAT (Ethernet for Control Automa­tion Tech­nology) offers every­thing modern automa­tion requires and combines this with the simplicity of tradi­tional fieldbus systems. As one of the fastest indus­trial Ethernet tech­nolo­gies, it is ideally suited for use with decen­tral­ized drive tech­nology, but to really benefit from this in appli­ca­tions, the drives should offer more than just a normal EtherCAT inter­face.


Inte­grated oper­ating modes make it easier to adapt to the indi­vidual task and prac­tical features make commis­sioning and servicing much easier. If a high power density and opti­mized control are then added to the mix, there is no reason why it should not be possible to achieve effi­cient plants and machines with network fuction­ality.

EtherCAT was devel­oped as a real-time Ethernet protocol specif­i­cally for indus­trial use and enables very fast trans­mis­sion of large amounts of data between the various compo­nents of an automa­tion system. It is flex­ibly scal­able and very robust and resis­tant to inter­fer­ence thanks to the ring struc­ture in commu­ni­ca­tion as well as decen­tral­ized design. The ECI-63 internal rotor motors from ebm-papst’s modular drive system  are now also avail­able with EtherCAT inter­face to ensure that these advan­tages for drive tech­nology can be exploited to the full. To achieve this, a tried-and-tested controller for EtherCAT commu­ni­ca­tion has been installed in the elec­tronics module along­side the power elec­tronics.

BLDC internal rotor drive in the ECI-63 series with EtherCAT inter­face and a wide range of inte­grated func­tions. (Photo | ebm-papst)

The possi­bil­i­ties offered by func­tions already inte­grated in the control elec­tronics (K5) can now also be conve­niently used in the network and the drives then process complete program sequences inde­pen­dently of the PLC/control system. In conjunc­tion with a safety control system, the TÜV-certi­fied STO (safe torque off) func­tion with perfor­mance level D and SIL-2 is also inte­grated into the drive elec­tronics for torque shut­down in hazardous situ­a­tions, for example in mobile robots or auto­mated guided vehi­cles.

Ready for use in no time

When devel­oping the drives, the focus was on the plug & play concept so that the user can get started right away and so that config­u­ra­tion and commis­sioning effort is reduced to a minimum for indi­vidual tasks. The EtherCAT SubDe­vice Infor­ma­tion file (ESI file for short) is avail­able for the drives – this file defines commu­ni­ca­tion between master and slave similar to the Elec­tronic Data Sheet in CAN (EDS for short). This means that a connec­tion to the drive can be estab­lished in any devel­op­ment envi­ron­ment and an appli­ca­tion can be put into action with just a few clicks of a mouse. If a user wants to control the drive directly from the PLC, pre-assem­bled struc­tures provide addi­tional support and example programs are also useful for inte­grating the drive using common motion libraries based on the CiA402 drive profile (CAN over EtherCAT).

The “jerk-limited” option enables accel­er­a­tion processes in the profile modes to be as gentle as possible. (Photo | ebm-papst)

In addi­tion, there are three different oper­ating modes: a speed and posi­tioning profile in which the drive calcu­lates its own path, including a homing func­tion, for refer­ence travel. Accel­er­a­tion and braking ramps can be adjusted indi­vid­u­ally in this profile.  In addi­tion, the “jerk-limited” option means that accel­er­a­tion processes are as smooth as possible. The latter can be essen­tial for appli­ca­tions in mobile conveyor tech­nology in partic­ular. The “Cyclic Synchro­nous Posi­tion Mode” is also already inte­grated for precise synchro­niza­tion of several axes.

Reduced commis­sioning effort

“Cyclic Synchro­nous Posi­tion Mode” opens up conve­nient options to the user in prac­tice, as the drive can be inte­grated as an NC axis at the touch of a button in the popular TwinCAT system manager, for example, and only a few settings need to be changed, such as the maximum encoder reso­lu­tion or the refer­ence speed. Refer­ence projects, for example, also provide assis­tance here, as data can be easily be taken over from them and they already contain expertly adjusted speed feed-forward for the controller. All this signif­i­cantly reduces the program­ming effort for the user, as has already become evident in prac­tice:

In the TwinCAT System Manager, the drive can be inte­grated as an NC axis at the touch of a button. (Photo | ebm-papst)

In a mechan­ical engi­neering appli­ca­tion, different weights had to be lifted depending on the automa­tion solu­tion required by the customer – some­times one drive can deal with this chal­lenge, but often four or even six are neces­sary. In the past, the machine builder kept the axes in sync via the PLC and CAN bus, which worked well, but always meant program­ming and initial config­u­ra­tion effort was required. In TwinCAT, it can now pair the drives with each other much more quickly and keep them in sync, saving a lot of time during machine setup.

MTPA for highest power density

The new ECI-63 drives with EtherCAT inter­face have even more to offer, for example inte­grated, field-oriented commu­ta­tion with MTPA (maximum torque per ampere) increases the power density and ensures higher torques and speeds. The motor is opti­mally utilized at every oper­ating point and it can be accel­er­ated more quickly or oper­ated for longer at a given oper­ating point. This reduces the thermal load on the motor and means that it consumes less current at the oper­ating point. The basis for this MTPA method is provided by the special design of the rotor with “buried” magnets fixed without adhe­sive, which support the magnetic field effect signif­i­cantly better than the usual surface magnets. At the same time, the rotor design ensures low cogging torque.

Compar­ison of the motor prop­er­ties with and without MTPA. (Photo | ebm-papst)

ID switch for Hot Connect

When designing the ECI-63 drives, the devel­opers took into account another detail that can signif­i­cantly shorten service times, in other words two addi­tional ID switches. EtherCAT addressing is normally based on the order of the nodes, but thanks to the ID switch, “Hot Connect groups” can be created with a fixed address in TwinCAT. For example, pre-config­ured sections can be removed from data traffic and added before start-up or during plant oper­a­tion. After main­te­nance measures are performed on this type of group, the config­u­ra­tion is imme­di­ately avail­able again, without the need for specialist inter­ven­tion.

The drives are part of the modular drive system from ebm-papst and can be config­ured in no time. (Photo | ebm-papst)

The drives are part of ebm-papst’s modular drive system and can be config­ured within a short time, i.e. combined with gear­boxes, encoders, and brakes. Stan­dard­iza­tion enables short delivery times to be achieved and all drives also meet the require­ments of the IP54 degree of protec­tion, and option­ally also IP65.

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