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Speedy digital servo drive is software adjustable

An Inmoco product story

Edited by the Engineeringtalk editorial team Jun 25, 2002

The novel Saxophone digital servo drive can be supplied as a fully digital velocity mode amplifier, as a CANopen network drive or as a stand-alone motion controller for single-axis servo control.

The highly integrated design of Inmoco's Elmo Saxophone digital servo drive provides unmatched flexibility, enabling the drive to be supplied as a fully digital velocity mode amplifier, as a network drive in distributed motion systems using the CANopen interface, or as a stand-alone motion controller for single axis servo control.

In all these operating modes the Saxophone design ensures excellent levels of linearity and response, and smooth motor operation via a digital sinusoidal commutation feature The ease of configuration, setup and tuning and the simplicity in mounting (panel or DIN rail) of the new Saxophone make it the ideal product for OEM machine builders.

As such it conforms to all relevant CE regulations and meets all the requirements of UL508c.

Designed particularly for high performance automated machinery, the Saxophone integrates a position loop, sinusoidal commutation and both digital current and digital velocity loops, the latter two featuring automatic offset adjustment.

Conveniently, adjustments to these loops, and to motor commutation functions, can also be undertaken via an RS232 serial communication link.

This is achieved using Windows-based Composer software, which is part of the automated setup, startup and tuning package that supports the amplifier.

The advanced full wave PWM switching of the Saxophone servo amplifier, with its up to 20kHz switching frequency (10-20kHz selectable), ensures high motor operating efficiencies at the rated current.

In addition, the amplifier's sinusoidal commutation function helps to maintain smooth motion and low torque ripple at low speeds.

This allows nearly constant torque throughout the motor cycle to be achieved.

Added to this, a zero deadband feature ensures that motor transitions from forward to reverse are seamless, and linearity is also excellent.

Rated for operation in the range from 3 to 14A (RMS), the Saxophone series is able to operate directly from either a three-phase 400V AC supply or a single-phase 240V AC line.

A major feature of the unit is that the control and the auxiliary supplies are derived from a 24V AC/DC supply that is isolated from the internal DC bus.

This allows a safe and an economical "power backup" feature that is essential for positioning systems.

In addition, an optional external backup supply enables the user to keep the micro-controller part of the amplifier alive when the main power is shut down in case of an emergency.

The flexibility of the Saxophone amplifier for OEM use is enhanced by the number of feedback options available.

In addition to standard high-resolution resolver feedback other options include encoders with Hall sensors, encoders only and Hall sensors only.

The microcontroller part of the Saxophone amplifier package is designed to detect, process and report a large number of possible fault conditions.

These are handled and reported through the communication line, but some are treated with a higher priority (especially those that could damage the system components) and are displayed for immediate attention on the seven-segment LED display.

The Saxophone also possesses a comprehensive range of protective features against a range of conditions, including excessive temperature, under/over voltage, loss of commutation signal, short circuits between the motor power outputs and between each output and power input return.

Protection is also provided against failure of the internal power supplies, loss of velocity feedback and high velocity and communication errors.

(This was Engineeringtalk's Top Story on 24 June 2002).