Those who rely on AC drives in complex food manufacturing applications have come to realize that smaller is indeed better. Thanks to advances in electronics and materials, the latest generation of AC drives is more reliable, simpler to use and program, and delivers more functionality in a smaller footprint than ever before. And since drives play such an integral role in the food manufacturing industry – by giving processors the ability to optimize their yield, quality and throughput to achieve maximum efficiency – size has become a key factor.
One of the most valuable assets in a food processing facility is space. Smaller components, such as drives, reduce the space requirements of control cabinets, allowing for more room for food processing machinery on the plant floor. In addition, by improving the reliability of the drives, food manufacturing operations can avoid failures due to heat or failed mechanical components that can bring the process to a standstill. Unscheduled stops to result in lost production while the drive is being replaced and lost time as the process ramps up again. Also, food manufactured during the ramp-up time will not meet quality standards and must be thrown away, resulting in yet another loss. The impact can be devastating to a food manufacturer. Reliable drives, therefore, greatly minimize downtime and increase the operational efficiency of food manufacturing operations. This is one of the key factors driving the overall productivity of the processing application. How do engineers create variable-speed drives that deliver consistent quality and take up less space? The formula is simple – replace electro-mechanical components with smaller and efficient electronic technology. Engineers have successfully developed new drives with components that generate significantly less heat than previous generations of drives, helping to eliminate a major cause of drive failures. In addition, they have worked to reduce the amount of wiring needed and the number of wiring connection points, saving space and eliminating a potential failure and major source of electromagnetic noise. Here are some innovations that have advanced drive performance and improved reliability in food manufacturing applications. Reducing HeatHeat is one of the worst enemies of electronic performance, particularly in a small-footprint, high-use component such as an AC drive. To combat excess heat, design engineers have taken advantage of a wide range of new technologies:
• Improved IGBTs
The new generation of insulated gate bipolar transistors (IGBTs) offers attributes such as high switching speed, low conduction voltage drop and high current carrying capability – thanks to “trench technology” – that helps to lower the cost of systems while allowing the same drives to be effective over a broader range of food processing applications. Trench technology improves the resistance of IGBTs, reducing the heat generated as a byproduct of IGBT operation. Less heat generation in the transistor means better thermal efficiencies, which translates into a more reliable drive. When there is less heat to dissipate the drive can be engineered in a smaller package. This gives engineers a cost-effective alternative to use the same drive for numerous food manufacturing applications: mixing, heater/blowers in confection ovens, to simple material handling.
• Nanocrystalline Core Technology
Like IGBTs, improvements in the core material used in a drive’s electromagnetic compatibility (EMC) filter offer another key advancement in reducing heat. The latest generation of EMC filters uses nanocrystalline material, an amorphous structure that is highly permeable compared to the ferrous materials traditionally used in EMC cores. Nanocrystalline material provides higher inductance and, consequently, generates less heat because it is permeable. This allows designers to use a filter that is 20 percent smaller than those found in previous generations of drives, freeing up valuable space.
• Improved Heat Sinks
Virtually all power electronic devices feature a heat sink that is designed to radiate heat away from the components inside. A well-designed heat sink is essential to drive reliability because it dissipates unwanted heat that can lead to component failure. Engineers have developed a heat sink fabricated of a unique aluminum alloy that transfers heat better, allowing a smaller heat sink to dissipate heat more efficiently. On average, the heat sink size can be reduced by 10 percent when using this new alloy. Again, this frees up manufacturing space for critical processing equipment.
Eliminating Potential Failure-Points
Heat isn’t the only enemy of drive performance in food manufacturing, however. Failed mechanical components and electrical connections also contribute to drive failure. New AC drive designs eliminate these components, greatly increasing reliability.
A controlled input bridge is a combination of diodes and silicon controlled rectifiers (SCRs) that convert incoming AC power to DC power. Replacing mechanical components with an input bridge controlled by a microprocessor reduces its size and also makes it more reliable because it is a solid state package.
Replacing traditional wiring and wiring connections with laminated bus technology, which is used for carrying high-power current within an AC drive, is another significant innovation in food processing applications. Bus technology greatly reduces drive size while also eliminating electrical noise.
Modern drive technology advancements continue to make new and better solutions available to component designers in food processing applications. Understanding and taking advantage of these advances can help manufacturers optimize their processes, prevent drive failures and reduce overall downtime.
