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DSP-based microstepper takes Eurocard form factor

Edited by the Engineeringtalk editorial team Nov 10, 2003

At Southern Manufacturing next February Smartdrive will launch the T-Series: a new Eurocard implementation of the company's Taranis ultrasmooth DSP-based microstepping drive/controller.

At Southern Manufacturing next February Smartdrive will launch the T-Series: a new Eurocard implementation of the company's Taranis ultrasmooth DSP-based microstepping drive/controller.

At the heart of the Taranis technology is a super-fast digital signal processor (DSP) with dedicated peripheral functions that enable direct precise control of the motor current switching devices.

The use of direct control, combined with adaptive mathematical modelling software, allows the winding current waveforms to be controlled very accurately, resulting in the elimination of most motor noise.

In addition, it enables extremely smooth motion to be achieved, with over three million steps per revolution, as well as adapting to any motor nonlinearities.

This level of control makes the T-Series particularly attractive in scientific applications, where such fine control is desirable but until now has been largely unachievable.

The T-Series can be used in two fundamental modes: a step and direction slave mode which emulates a traditional microstepping drive and an intelligent controller/drive mode capable of self-contained operation without the need for a separate signal generation source.

Both implementations use a base microstepping resolution of 51,200 steps per revolution.

In slave mode, the T-Series Eurocard receives an external motion clock signal, but intelligently converts the input to ultra-smooth microstepping pulses.

This feature ensures smoothness and reduced noise, even if the input source is operating at lower resolutions - with full- or half-stepping frequency, for example.

Using the full potential of the internal Texas Instruments DSP system, the intelligent Eurocard becomes a stand-alone combined drive and controller, supported by a 130-keyword Basic language, Flash memory, RS485 serial port and Windows-based development tools.

By utilising the serial port in multidrop mode, it is possible to "daisychain" multiple Eurocards for multiple-axis applications.

Designed around advanced surface-mount technology, the compact (3U x l60mm Euromodule format) unit uses rugged MOSFET power stages and a compact high-efficiency heatsink to obtain continuous operation from the drive, with natural free-air convection cooling normally being sufficient.

A standard module width of 9HP allows as many as eight drives plus a power supply to be housed in one 19in-wide rack.

Winding current can be easily set to match the motor characteristics to the load while the motor is running, either by a rotary switch on the front panel or a resistor connected to the drive backplane.

Five current ranges from 0.5 to 16.5A are available.

In addition, the drive has a boost input which increases current output by 30%, a useful feature for providing rapid acceleration and one that can also be used continuously.

A feature known as comprehensive dynamic protection (CDP) monitors the drive's dynamic environment and reacts within 5us to protect the unit against all motor winding faults, including short-circuit to winding, short-circuit to ground and low-inductance winding.

In addition, there is protection against irregular motor supply voltage, low logic supply and overtemperature conditions.

Reliability is ensured by the use of conservatively rated components combined with thorough production testing of all units under simulated fault conditions and for correct thermal performance.