The Drive for Simplicity: Defining Trends in Motor Drives

Progress in AC drives technology is making life ever easier for operators.

By Ilpo Ruohonen, Mika Paakkonen, Mikko S. Koskinen

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ABB offers one of the world's largest portfolios of AC drives, serving an expanding horizon of applications. With increasing demands for flexibility, reliability and ease of use, ABB has come up with a number of solutions to make life simpler and cheaper for its customers.

By combining functions and cutting part counts, ABB has reduced the size of its drives while enhancing their reliability. The company has also developed a simplified set-up procedure using a harmonized keypad and software wizards that can be used across the ABB drive family. More complex programming can be carried out using ABB's Adaptive Programming utility and parameters can be transferred between drives using ABB's patented FlashDrop technology.

All these advances are part of an on-going effort at ABB to offer cutting edge technology in high performance, yet user-friendly systems.

Traditionally, the primary use of drives has been in such applications as powering pumps, fans and conveyors. And while they will continue to be used in these applications, today's end-users have a very different approach to that of a decade ago.

Drives are now fully developed and are therefore more widely accepted as a product. The need to answer the question, "what does it do?" has been replaced by the expectation that the drive will "just do it." This shift in attitude brings with it the assumption that the drives are simple to buy, simple to install, simple to start-up, simple to commission and simple to own and run.

At the same time, drives are finding new applications: in exercise machines, pizza ovens, honey centrifuges and car washes. In these applications, the drive is very definitely considered a commodity, and the original equipment manufacturers (OEMs), who may not traditionally have used drives, are once again demanding pure simplicity. In fact, a recent survey showed that simple controls and set-ups (70 percent) and convenient operator interfaces (53 percent) were rated as "very important" by AC drives users.

The quest for miniaturization

Simplicity and ease of use manifest themselves in many ways. The mere fact that drives can now be used in domestic washing machines is a testimony to their extreme compactness. Drives have become smaller, more -capable, easier to use and cheaper, by orders of magnitude.

Smaller drives are easier to install. Panel builders are able to fit more drives into a standard cubicle, so the whole panel can be smaller. This allows the use of smaller and less costly control rooms. It also becomes easier for OEMs to fit drives into their equipment. A classic example of this is in cranes, an application that has always had very limited space for the drive.

The reductions in drive size have resulted from the use of fewer components, greater packing density, improvements in semiconductor technology and improved cooling techniques. In fact, there has been a ten-fold decrease in the size of drives over the past 10 years.

Driving down cost

An additional benefit of reducing the component count in a drive is that it cuts costs. ABB predicts that, over the next few years, the parts count of its drives will be reduced by approximately 20 percent through the use of integrated electronics to eliminate separate components such as external flash and RAM memories and analog/digital converters. Mechanical parts are also being integrated, for example, by combining frames and enclosures, allowing them to perform multiple functions.

Reducing part count also enhances reliability: fewer parts mean fewer interfaces and fewer mechanical fixings, which are often a source of failures.

Improved cooling

Advances in the development of power semiconductors have also helped to improve drives. A reduction in the power losses per-unit-area-of-silicon used means that the same silicon area is able to handle more power. This has enabled smaller semiconductors and reduced the need for cooling within the drive. This, in turn, allows the use of smaller heat sinks and reduced air volumes inside the drive – the result is smaller and smaller drives. The only limitations are the terminals because these must accommodate cables that are large enough to carry sufficient current to the drive.

But it is not just the development of power semiconductors that has enabled miniaturization of drives. Of prime importance is the technology used for cooling. Considerable R&D effort is being put into developing new cooling techniques, as well as into reducing the need for cooling.
While air cooling is likely to remain the dominant technique, liquid cooling is finding increasing use in areas such as wind power, transportation and marine applications, as reflected by the recently launched, liquid-cooled ABB industrial drive.

Increased functionality

These ever-shrinking drives contain ever-expanding functionality – thanks to developments in software. Today's software monitors, diagnoses, configures and archives information and -parameters concerning drives in industrial plants.
Set-ups are performed entirely using software functions, and then downloaded to the appropriate drives.

The set-up information is archived for future retrieval. To obtain the full benefit of this technology, however, operators must still refer to the user manual. ABB is striving to develop -intelligent control panels that will -significantly decrease the need for -paper-based manuals. The secret, though, is to find an easy way of accessing this kind of functionality. Enter the keypad.

The ideal keypad

ABB's R&D team scrutinized every -aspect of how a user interfaces with a drive and developed what it believes is the most user-friendly keypad ever. The keypad for the ABB standard drive features only eight soft keys, through which all parameters, functionality and set-ups can be accessed.

Even the actual buttons on the keypad were carefully selected to ensure that just the right level of built-in resistance gives the user the feeling of stability and accurate key-press detection.

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