Feature 40 years of drives & motors
weight, size, assembly and cost advantages. Digital technology also opened the floodgate of increased functionality on a drive – “It’s only software” was a common statement of the marketing team, looking to include a differentiating feature to give a customer a system cost benefit. In the late 1980s IGBT technology arrived, heralding the era of relatively quiet, efficient and ultimately reliable AC drives. Drives continued to get smaller, easier to use and volumes grew.
A developing technology The mid 1990s saw the introduction of the first truly Universal drive, which by parameter selection only, met, without compromise, the diverse requirements of an open loop (vector) drive, a closed loop drive, a servo drive, and a sinusoidal grid-tied converter. This was also the birth of what has become known as the intelligent drive with user programmable functionality and Fieldbus connectivity. Multi-axis requirements inspired a range of developments: multiple drives in a single package; drives with the position and speed loop embedded in the encoder housing on the motor itself. This later concept processed position information close to the source, avoiding noise problems, which allowed dramatic improvements in con- trol resolution, stiffness and reduced wire count between drive and motor. In the early years of the new millennium, rapid change continued. Users, looking at drives as components in a large control system, demanded ever greater connectivity. The Fieldbus ‘wars’ were raging with passionate claims for many systems (I counted over 200 in a 12 month period), most of which have since disappeared. The war has now morphed into the Ethernet wars, with advocates of the different protocols all predicting dominance.
Communications
Modern communications systems open up new opportunities for the highest levels of system performance through dynamic distributed control. Synchronising all control loops (with <2µs jitter) within and between drives brings a new level of determinism. Functionality has been greatly enhanced to a level where PLC func- tionality is available for users to pro- gramme very complex and demanding system applications including motion control with drives, some having multi-axis interpolation capability. Ongoing development is driven by customer needs, component technol- ogy, design techniques and the vision of the industry. Power devices drive efficiency, whilst microprocessor performance yields not only improved motor shaft performance, but
S18
enhanced functionality. Ease of use remains a key focus.
While there remain specific motor types and controls best suited to certain applications, users should not have to deal with a plethora of different user interfaces and modes of operation. While the Universal drive has been a major step forward,
ambitions for a low-carbon economy. Government targets are for a 34% cut
in 1990 CO2 emission levels by 2020, and a greater than 80% cut by 2050. Achieving these levels will require action on many fronts, but consider the potential of motor drives. Industrial electric motors account for more than 60% of all electrical energy
‘Industrial electric motors account for more than 60% of all electrical
energy consumption. The application of a drive results in typically a 30-40% reduction in energy used, and could be applied in over 50% of applications. This would result in a 9% reduction in all electrical energy consumption – a significant contribution achieved at modest cost’
more will come. Similarly, automatic tuning routines in drives, matching the drive to both motor and mechani- cal load, ease the burden on the commissioning engineer. But, further advances are needed. Robustness of control and stability even within non rigid structures will be important future areas. Significant advances occur when users and drive designers get together and consider system solutions holistically.
Driving the future Amazingly, some drives are sold to customers today who have no motor to control! These have been purchased purely to use the comprehensive auxiliary functions. Will manufacturers continue to pour more and more functionality into drive products? Perhaps not, as drives are, despite LCD displays with menus, macros and wizards, already bewil- dering for many users. The drive may become like a PC, with a basic operat- ing system and a limited number of core functions, and then have functionality loaded by the user. The market for industrial drives will continue to grow apace. Energy efficiency will at last be a substantial driver of growth, through both regula- tion and common sense. Automation drives the development of the indus- trial world, and drives are at the heart of automation. Alternative energy sources such as wind and photo- voltaic rely upon efficient power elec- tronic energy conversion, and drives companies are well placed to play a significant role in this market. Spin off’s and leverage will result.
An important solution
Industrial drives are very important to the UK. The drives industry provides employment for over 12,000 people, and contributes in excess of £1 billion to the nations GDP.
Furthermore, they are critically important to achieving the UK's
- 40TH ANNIVERSARY SUPPLEMENT - Design Solutions 1971-2011
Control Techniques’ Unidrive SP zero drive
consumption. The application of a drive results in typically a 30-40% reduction in energy used, and could be applied in over 50% of applica- tions. This would result in a 9% reduction in all electrical energy con- sumption – a significant contribution achieved at modest cost, as payback on applications tends to be within months rather than several years.
Control Techniques T: 01686 612900
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