The Drive for Simplicity: Trends in Motor Drives

Progress in AC drive technology is said to be making life easier for facility operating staffs.

By Ilpo Ruohonen, Mika Paakkonen and Mikko S. Koskinen, ABB Drives June 18, 2007

By combining functions and cutting part counts, ABB is one firm thatprogramming utility and parameters can be transferred between drives using its patented FlashDrop technology.

All these advances are part of an on-going effort

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 The need to answer the question, What does it do, has been replaced by the expectation that the drive will just do it.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%)and convenient operator interfaces (53%) 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

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.ted, 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

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.

To develop the keypad, ABB compiled 11 guiding usability principles that consider all aspects of visibility and readability; the type of text and terminology, and the icons used. Based on this, ABB is now harmonizing the keypads of all of its drives. A common look and feel allows the users to switch between different ABB products easily, without having to go through a time-consuming learning process for each new product.

The true value of the keypad The advantages are not all aesthetic. There is a real financial incentive for customers to choose this keypad and its intuitive commands. Most equipment investment decisions now carry a proviso for fast installation to ensure that production will start rapidly and smoothly. Paramount is the speed with which a machine can be up and running after the installation of new equipment or after a maintenance shut down. If a machine breaks down, it can cost the operator $20,000 per hour, so easy set-up and commissioning are a priority. Such urgency increases the risk of errors in installation and commissioning. These can be overcome by eliminating manual intervention wherever possible; the keypad is central to this aim.

These guiding principles, and the fact that there are only eight keys on the keypad, suggested the need for intuitive assistance. ABB developed a series of wizards aimed at guiding the user through various procedures. There are maintenance assistants, diagnostic assistants and, one of the most widely used, a start-up assistant.

The magic of wizards With the start-up assistant, a tool is provided

A common look and feel allows the users to switch between different ABB products easily, without having to go through a time-consuming learning process for each new product.

Specialist HMI FlashDrop is a patented new technology

While the HMI is clearly important, ABB has also been looking at ways to simplify customer applications using the functionality packed into a drive. One of the drivers is the customer’s interest in total cost of ownership, which includes commissioning, swap-outs and maintenance.

Application-specific solutions AC drive users can now reduce costs even more by employing application-specific drive solutions. These drives incorporate incremental functionality that supports specific applications such as fan and pump control, mixers, or crane controls. They can reduce the total cost of ownership through shorter start-up times, lower integration costs, and improved machine productivity.

Time savings during commissioning can range from one to several hours. The process does not require expert programmers and, therefore, saves the considerable expense of sending commissioning engineers around the globe to fine-tune individual drives.