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Drives: yesterday’s technology or tomorrow’s unsung heroes?

13 November 2015

Inverter drives: have they changed much over the past 20 years? Parker’s David Blood and Grant Shoebridge discuss developments and make their predictions for drive technology.

Cutaway of an Energy Grid Tie container, showing the battery racks and Parker inverters
Cutaway of an Energy Grid Tie container, showing the battery racks and Parker inverters

Inverter drives: have they changed much over the past 20 years? Not at first glance; with underlying drive technology, there hasn’t been a significant leap forward. The industry is still using IGBTs, and while these may have evolved a few generations, fundamentally it’s the same technology underneath. Yet this apparent lack of evolution belies a wide range of advancements and innovations in engineering.

Most engineers are familiar with the use of in-factory drives. But the core products used in industrial environments are increasingly becoming widespread in other industries, such as mobile and energy applications.

One area of significant change over the years has been the trend towards high power, low-voltage, variable speed drives (up to 2MW or more). This development has triggered the need for additional cooling measures, to dissipate the extra heat generated. Typically, water is viewed as the obvious cooling solution, but there are alternatives; for example, Parker offers a refrigerant system providing benefits such as high efficiency and low power device temperature variation.

Energy efficiency for drive technology has also improved. That’s mostly because of improvements in the silicon technology, coupled with more intelligent use of cooling strategies. Historically, fans inside the drive would run the whole time; now, there’s greater operational control and the ability to switch cooling on and off when it is needed.

The market for variable speed drives has grown substantially, with hundreds of suppliers competing in the pan-European marketplace. These providers tend to fall into one of three categories: major industry players; price-driven companies with less emphasis on feature sets and innovation; and businesses that have focused on particular markets and developed specialist features for market-specific applications.

The processors being used in today’s drives are also much more powerful, as the embedded technology that runs inverters has come a long way in terms of speed, memory capacity and communications capabilities. For example, the latest generation of drives features Ethernet ports, serves web pages and can potentially participate in the Internet of Things (IoT) – and that’s an important trend that is set to continue.

Embracing connectivity and the IoT
As the IoT evolves and is embraced more widely, engineers can expect to see an increase in product launches with saleable IoT features. But that’s for tomorrow’s - or next year’s - agenda, rather than today’s.

For now, Parker is investing considerable resources in product development for connectivity; the goal is to make life easier for customers by launching products that are easy to use across multiple applications. Alongside this, enhanced software features offer engineers greater flexibility.

For example, more and more suppliers are now using Codesys, the IEC61131 programming platform. The beauty of using Codesys is its flexibility, especially for engineers working with multiple suppliers – or wanting to switch from one to another without rewriting all the software inside their drive.

Over the past decade, Parker has extended its reach into new areas of business. There is still demand for the standard industrial drives that are a familiar feature in factory settings; but increasingly, the business has also moved into new specialist markets. For example, in the mobile market, it’s all about marrying hydraulic expertise on vehicles together with electrical motors and rugged inverters.

Another major shift has been the development of renewable energy, and making inverters grid-facing. Large-scale battery storage on the power grid is a business stream that did not exist twenty years ago; but it’s very relevant today, with clear political intent to decarbonise the power grid as much as possible. 

The UK economy is growing, but our carbon intensity is dropping. There is a push for more and more intermittent renewable generators being placed on the grid, such as wind turbines and solar farms. At the same time, existing thermal plants are coming under scrutiny, with some being taken off the grid because they are not as profitable as they once were; so investment decisions are becoming harder. 

The combination of these two factors (increases in intermittent green power with the removal of conventional plants from the grid) makes it very difficult to balance supply and demand on the power grid, leading to power quality issues and, potentially, outages as this trend continues. In the coming years, it’s likely that a cohesive national strategy will be developed for grid-based energy storage – and the use of inverters may well have a central role to play.

Predictions for technological advancement
The next big shift for inverter drives is probably the trend towards higher-temperature, higher-voltage devices, such as the introduction of silicon carbide technology, which can run harder and hotter. This development could dramatically change both the size and efficiency of variable speed drives. In the coming years, the cost of this technology is likely to reduce and become more standardised – which will help to significantly reduce manufacturing costs and, in turn, trigger demand.

Another area to watch is the harnessing of big data. So far, the industry has not really harnessed the potential for big data that drives and other industrial equipment are increasingly able to provide. But we’re starting to see products where this is potentially achievable. For example, smart power meters (that can be read over the web) are already being used for billing; build on that functionality to capture and store more information online, and the potential for big data analytics becomes obvious. Imagine if your drive could spot bigger and bigger tool pulsations over a given period, and started to self-diagnose possible system problems or highlight the need for maintenance spend.

The popularity of application-specific drives is likely to grow, and the numbers of inverters with applications and displays tuned to specific market needs are likely to increase. And that’s critical for certain sectors of industry where application knowledge is either non-existent or in decline, as companies remain under pressure to streamline their resources.

If a product is tuned to a specific application, it becomes easier for people to perform key tasks, as much of the ‘smart stuff’ has already been programmed into the inverter. Drives such as Parker’s AC30, for example, which can be configured into a refrigeration or hydraulics drive just by changing the user application inside it, mean there’s no need for expensive product redevelopment. And with options available to vary applications for specific markets, demand is expected to increase over the coming years.

So, despite the basic technologies behind inverter drives staying constant over the past decade, it’s clear that they are far from being ‘yesterday’s technology’. With inverters finding new markets and new applications, they hold potential for supporting significant change in industry, for years to come.

Dr David Blood is marketing manager, Energy Grid Tie Division, Parker Hannifin
Grant Shoebridge is business development manager, Parker SSD Drives

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