The trend in automa­tion has thus far been toward compo­nents with maximum flex­i­bility that can be assem­bled from a set for quick customiza­tion. Now minia­tur­iza­tion of the elec­tronics makes it possible to go a step further by “replacing” some hard­ware func­tion­ality with soft­ware. Elec­tric drives are an example of this trend: Now a devel­oper no longer needs a number of different elec­tric motors but can use inte­grated elec­tronics to program modern EC drives for an application’s drive profile, e.g. torque-controlled for a thread winder or speed-controlled for pump appli­ca­tions.

Figure 1: Cross-section of drive with K4 elec­tronics module and EtaCrown® angular gear.

Automa­tion increas­ingly calls for the ability to elec­tron­i­cally regu­late motors for vari­able speed or torque or limited output as needed. ebm-papst has been observing this trend for some time and has mean­while inte­grated the entire control system and power elec­tronics in the drive unit’s K4 module (Figure 1), expanding the range of uses for modern, elec­tron­i­cally commu­tated drives.

Whereas conven­tional DC drives needed to be mechan­i­cally designed for certain torque or speed ranges, EC motors are intrin­si­cally able to cover much more exten­sive ranges. Now an inte­grated control system makes it possible to fully exploit this poten­tial without compro­mising on reli­a­bility. In addi­tion, program­mable drives can be more easily inte­grated into appli­ca­tions and reduce cabling effort and instal­la­tion time.

Config­urable drives

Modern EC drives excel thanks to their rugged construc­tion; their magnetic circuits can easily with­stand even the most extreme mechan­ical and elec­tro­mag­netic stresses. The result is an enor­mous poten­tial output at maximum effi­ciency, though to date the full output range has seldom really been utilized. That will change radi­cally with the new control elec­tronics, desig­nated “K4,” which monitor the drives and enable 100% motor output exploita­tion with the spec­i­fied para­me­ters for optimum utiliza­tion of drive bene­fits such as full motor torque from zero speed with high short-term over­load capacity for appli­ca­tions such as rapid accel­er­a­tion of heavy loads. With recon­fig­ured para­me­ters, the same motor can also wind even the finest thread at vari­able speed, or it can be oper­ated like a stepper motor to auto­mat­i­cally move to specific posi­tions on command.

Bene­fits of an inte­grated control system

Figure 2: Screen­shot of Kick­start tool: the menu enables fast config­u­ra­tion of para­me­ters with the mouse.

A flex­ible control system makes it possible to tailor a drive to an application’s require­ments. Three oper­ating modes are possible, with the motor working in speed, posi­tioning or torque mode to reduce the burden on external control systems. The fully inte­grated control elec­tronics provide several analog and digital inputs and outputs, which can be config­ured via an RS485 inter­face.

The drive’s func­tion­ality during oper­a­tion can also be controlled by moni­toring numerous quan­ti­ties such as voltage, current, speed, temper­a­ture, etc., so that users can concen­trate on their core exper­tise – devel­op­ment – and drives operate with optimum values in the permitted range of perfor­mance data. In addi­tion, the number of drive vari­ants needed by users with broad require­ments profiles is reduced substan­tially, and subse­quent adjust­ments during oper­a­tion are also possible.

The control and power elec­tronics make these modern drives suit­able for a wide variety of uses.

The control and power elec­tronics make these modern drives suit­able for a wide variety of uses and can be config­ured quickly using the powerful “Kick­start” PC config­u­ra­tion tool (Figure 2). An endless variety of appli­ca­tions is conceiv­able with the concept described here; two prac­tical exam­ples are described below.

Use as a steering motor

Precise and repro­ducible posi­tioning is needed for an active rear axle in trans­port vehi­cles, an example of the use of the ECI 63.20-K4 as a steering motor. The vehicle’s control system supplies a target angle to the motor, which works in stepper motor mode. The drive then converts this input into a corre­sponding steering angle auto­mat­i­cally.

Since the inte­grated control system preprocesses the steering angle inputs for the motor and passes them on to the power unit, the user need not be concerned with motor control and can concen­trate on the core task of correct posi­tioning. In addi­tion, depending on input, the current, voltage, posi­tion, speed and other para­me­ters are constantly moni­tored with a diag­nostic tool and alarms are issued when neces­sary. A config­u­ra­tion tool helps with famil­iar­iza­tion, signif­i­cantly reducing the time needed for devel­op­ment and testing. Only a few mouse clicks are needed to quickly assemble entire func­tional sequences, which can be acti­vated through two digital inputs. Thanks to the drive’s small size and its over­load capacity, the steering unit can be built small and light.

Drives for intral­o­gis­tics

Figure 3: ECI series and VDC series.

With their compact designs and high over­load capacity, the drives in the ECI and VDC series lend them­selves to appli­ca­tions char­ac­ter­ized by confined spaces and dynamic require­ments. A good example is a diverter unit used in conveyor systems. In this case, a drive based on the VDC-3-49.15-K4 motor is used.

Only 120 mm long and 63 mm in diam­eter, it contains the motor, the plan­e­tary gear and the asso­ci­ated K4 elec­tronics. “Here the customer bene­fits from both the compact design and the fast config­u­ra­tion of the drives (Figure 3),” says Dominik Häßler, a devel­oper at ebm-papst. “Via the elec­tronics, every motor can be config­ured to its specific drive task along the conveyor line, which opti­mizes the system while also lowering costs for spare part inven­tory. This dras­ti­cally reduces the number of different drive units.”

The customer bene­fits from both the compact design and the fast config­u­ra­tion of the drives.

In spite of their compact­ness, the drives trans­port pack­ages weighing up to 50 kg at a speed of about 1 m/s. The accel­er­a­tion needed for distrib­uting or diverting the pack­ages is approx­i­mately 2.5 m/s2. The drive bene­fits here from the high effi­ciency of the EC motors and their pronounced over­load capacity. Low dissi­pa­tion and compact motor design keep the thermal effects of high tran­sient load peaks manage­able.

Modular system plus soft­ware

Since the elec­tronics can only work within the power range dictated by the motor design, this motor series is also designed as a modular system, with a variety of compo­nents such as gear­boxes, brakes or elec­tronics modules being combined around a compat­ible EC drive to match the appli­ca­tion. The appli­ca­tion band­width of a drive config­ured in this fashion is further expanded by the K4 elec­tronics, which provide espe­cially precise control to unfold the entire capa­bility of each EC motor. Output ranges up to 400 watts for the ECI series of internal rotor motors and 120 watts for the elec­tron­i­cally commu­tated VARIODRIVE Compact external rotor motors.