AC drives add flexibility to pressing tasks

Edited by the Engineeringtalk editorial team Aug 8, 2006

Lenze smd drives have been used to provide accurate variable speed control for the world-famous Electrolux range of industrial ironing machines.

Lenze smd drives have been used to provide accurate variable speed control for the world-famous Electrolux range of industrial ironing machines.

The smd units range from 15 to 22kW for the larger machines and were chosen because they were both easy to set up, cost effective and compact, fitting inside the existing machine design envelope.

This application is a showcase example of why Lenze introduced the smd range of AC drives, essentially to bring inverter drive functionality and efficiency to a wider range of simple motor control applications (often replacing mechanical speed control such as friction based clutches, brakes, 2x speed gearboxes, baffles and dampers etc).

The smd breaks through what was the existing price barrier for AC drives while retaining high functionality and offering easy to use features.

The ironing machines retain a combination of familiar manual speed control via a hand operated knob (a potentiometer wired directly to the smd drive) that can be used to control the rotation speed of the cylinder, this comes as standard on all machines.

Advanced models employ an automatic function where the machine senses moisture levels and adjusts the feed rate accordingly.

The signal is fed back to the drive and the fine speed adjustment is made according to preset parameters.

Maintaining a consistent speed and pressure is essential for good ironing results as anyone who has successfully ironed a shirt will attest.

The manufacturer claims that the direct ironer advanced moisture management system (or DIAMMS) for short is the only plug-and-play system available on the market that takes the guesswork out ironing by automatically regulating the ironing speed.

The process relies on the company's experience and the accuracy of the smd drive unit to achieve smooth and precise drum rotation at fine speed increments.

The result is dry linen with perfect finishing; a fully automatic DIAMMS is also claimed to save energy, labour and ironing process time.

The items being ironed are being pressed as well as steamed, hence the torque loads are high and variable, and with only a limited amount of space to fit the drive into, the smd's compact size proved to be a bonus for the engineers.

In-line filters were also supplied, ensuring that EMC levels are met; whatever markets the machine is intended for.

Another major benefit to Electrolux is the innovative EPM memory chip; the EPM is dimensionally a 1cm cube that can be programmed and copied independently, it plugs directly into the front of the smd drives outer casing and means that each ironing machine can be commissioned without power being supplied simply by plugging in a preprogrammed chip.

The EPM chip can be copied any number of times in seconds using a handheld EPM programmer, the program can be copied from a master chip or from the memory on the EPM programmer and transferred from drive to drive in seconds.

On a production line of machines, not having to program each one individually is a massive saving in time and resources.

Service is also easier because Electrolux keeps master copies of each model's operating parameters and in case of any service issues the customer or service agent can simply be sent a duplicate chip in the post.

smd drives have IP20 enclosures and feature inbuilt overload protection, to prevent tripping and tolerate current spikes of up to 180%.

An internal memory allows for storage of the last eight faults, providing simple service diagnostics.

A class A EMC filter is built in on smaller drives as standard, and an optional footprint RFI filters are available for the larger three-phase 240 and 400V models.

Drives from the smd range offer three-phase AC output from both standard single- and three-phase supply voltages including 220V for export to the USA.

Options include DIN rail mounting kits, removable heatsinks for through-cabinet mounting and dynamic braking units, which are easily mounted within control cabinets.