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Flexible design brings VFDs to wider market

Nov. 23, 2021
VFD design is driven by desire for more safety, energy management and communication options

With worker safety and cybersecurity concerns growing, along with supply chain and workforce issues, these challenges are pushing manufacturers to build new solutions quickly. The Industrial Internet of Things (IIoT) continues to influence every aspect of industrial automation; and real-time data analytics, remote condition monitoring and asset optimization lead the digital trends for variable-frequency drives (VFDs).

Eight suppliers—SEW Eurodrive, Bosch Rexroth, Siemens, ABB, Schneider Electric, Hitachi Industrial Equipment & Solutions America, Danfoss, Nidec Control Techniques—discuss market trends driving VFD development and design, as well as predictions for the future of VFDs, including new applications and industries, more integration with system components and easier programming.

Customer and market trends for VFDs

Of all the customer and market trends identified, some manufacturers repeated three themes: safety, energy management and design flexibility. Integrated safety is becoming the norm, rather than the exception, and it’s being used beyond worker safety to improve production. With energy management coming to the forefront for many industrial automation applications, electric motors are a natural place to start. Manufacturers are being pushed to develop not only more efficient VFDs, but also incorporate solutions for integrated energy management. These solutions and smarter equipment have made VFDs a significant investment, maybe not suitable to the whole industry, but VFD applications are growing overall. Modular, flexible and scalable designs are enabling safer and more efficient VFDs for a wider audience.

Drive safe

The current market wants safety functions that are more reliable and easier to use. “The VFD has to provide integrated safety functions for safe torque off (STO); this built-in functionality provides a much improved and reliable way to provide an emergency-stop mechanism to stop the motor if an unsafe condition or if an e-stop occurs,” says Leo Young, business development manager, drive and automation, at SEW Eurodrive. “STO functions are designed to be fail-safe by removing all output torque to the motor, which allows the motor to coast to a stop. STO implementation removes the need to de-energize the VFD with upstream contactors, which could still have residual energy in the drive to power the motor or downstream contactors, which could disconnect the motor, but could damage the VFD. VFD manufacturers are implementing integrated-safety functionality and communications to provide a safer and more user-friendly way to integrate safety in the automation system.”

Safety is also being used to improve production. “Safety has become an important factor in machine building,” says Joaquin Ocampo, product manager for automation and electrification at Bosch Rexroth. “While STO is a valid safety solution, it does not help in the reduction of downtime. Machine builders and end-users understand the advantages of using safe -motion functions, such as safe limited speed, safe direction or safe stop 1. For example, machine builders can create safe zones, where one part of the machine can be set to safe state, while other parts of it continue to run at production speed. This keeps the production going and certain disruptions can be attended at the root of the problem and not by stopping the entire machine.”

Apart from increasing uptime, using safe motion can help in the reduction of scrap material, says Ocampo. “If the machine is set to safe state, it maintains the material in place, the machine is still holding on to material or tension. Adjustments could be done, using the enable signal and moving the machine in safe speed and then the machine can continue to operate without resetting the machine and losing material due to this process.”

Energy management

Sustainability and energy impact are key factors that manufacturers must consider for new designs. “There is more concern over energy consumption and shaving of peak demand, and, since electric motors use 60% to 70% of the electricity consumed in industrial applications in the United States, it is the natural place to start for reducing energy consumption,” says Young of SEW Eurodrive. “Energy-efficiency standards are being implemented around the world for minimum efficiency of motors to help reduce energy consumption, as well as carbon footprint. All of these things are driving VFD manufacturers to provide not only more energy-efficient drive and motor solutions, but also more robust networking, and software solutions to monitor and control energy consumption for optimizing processes to achieve a much higher energy efficiency from the system.”

The purpose of using VFDs is to provide only the power you need, but they do come with a significant cost. “Customers are seeking higher efficiency and reliability for their processes,” says Navid Binesh, senior technical consultant at Siemens. “This has been the major force driving adoption and utilization of VFDs. In low power markets, typically 150 hp and lower, the capital cost of VFDs is the determining factor in investment evaluation; however, as power rating grows, other factors such as operating cost of VFDs, such as cooling; reliability and availability, which dictate the downtime; and routine maintenance costs, which define the annual maintenance cost, are becoming more important. Today, customers understand that adding a VFD to a process is an investment, and it needs to be evaluated like other investments using methods such as payback period, breakeven time and return on investment.”

Design flexibility

VFDs are being used in more applications, as designs become more flexible to meet a wider swath of applications. “Reducing or eliminating the control panel enables the machine builder to offer a solution for customers to optimize floor space and simplify system complexity,” says SEW Eurodrive’s Young. “Field-mountable VFDs eliminate the need for the complex wiring within the panel by providing sealed units, as well as network and power cabling to withstand environmental conditions. A decentralized drive also reduces the energy consumption required by a drive panel by eliminating the heat generated in the control enclosure, which would require active cooling and increased energy consumption in the panel.”

Modular, scalable and flexible drive solutions allow design flexibility, says Young. “This is accomplished by providing motor-control solutions that are networkable and modular, which allows for simple integration into various applications and upper-level machine control platforms,” he explains. “The use of industry-standard industrial Ethernet communication protocols, such as EtherCAT, Ethernet/IP and Profinet, can provide a backbone for connecting devices, as well as machine modules to allow communication and coordination of all machine data. Also, providing a field-mountable decentralized drive solution allows machine builders the ability to provide a more distributed system architecture to reduce installation time and costs by allowing for a modular solution without having to wire back to a main enclosure. This type of field-mountable drive architecture optimizes floor-space utilization and eliminates up to 50% of the wiring cost by eliminating the requirement for large drive panels to provide a more flexible, scalable and modular solution. VFD manufacturers must be able to provide a modular scalable solution, which can provide a range of functionality from simple speed control up to and including intelligent VFDs, which are easily programmed, configured and started up with a single software tool or via an onboard keypad.”

End users and OEMs alike are looking for products that are easier to use, explains says David Orlikowski, LV drives regional engineer at ABB. “This has led to additions such as a common parameter structure across product families, plain text keypads and Bluetooth connectivity for ease of programming,” he says.

“Machine flexibility is a key market factor. Not only do machine builders want modular machines they also want machines that can accommodate multiple products with different dimensions, weights and design,” says Ocampo of Bosch Rexroth.

“Customers are now going a step further, looking for application-centric VFDs that offer more than just simple motor control,” says David Chen, senior offer manager at Schneider Electric. “These are designed specifically for certain applications with benefits targeting those domains. For example, VFDs have been used in fluid control for years and have generally been built with V/F2 motor-control curve to achieve energy saving as part of their standard offer. Now, these VFDs are being designed to be used in a broader range of industrial and residential projects, with embedded features specific to an application, be it pumps or fans, offering users greater benefits, both electrical and mechanical.”

Also read: Motors and drives become smaller, more powerful and more efficient

Other customer and market trends for VFDs

Manufacturers also identified other important trends for VFD design and development, which center around top trends for components throughout the industry: connectivity, integration with other components and data analysis for improved production.

Built-in communication and connectivity

“Connected devices such as VFDs provide access to the real-time data from the factory or warehouse floor, which allows you to make real-time decisions for process optimization for better control of your quality, processes and throughput,” says SEW Eurodrive’s Young. “This device data can be sent to a computerized maintenance management system (CMMS) for predictive maintenance to improve machine uptime and overall equipment effectiveness (OEE). It can also be used by a manufacturing execution system (MES) to help make decisions to respond to customer demands in real time. More manufacturers are requesting this data for the CMMS, MES, enterprise-resource-planning (ERP) system or warehouse management system (WMS), so motion-control suppliers are creating easier ways to share this data with their partners through the development of APIs, cloud services or web service or servers built into the device.”

Many very capable real-time Ethernet networks with the capability to provide synchronization of machine motion control are available, says Young, so picking just one may be difficult. “A VFD as a machine component has to have the ability to provide support to all of the major Ethernet networks on the market today to provide a flexible and easy-to-integrate drive solution,” he explains. “A VFD should offer integrated communication interface, which allows connection to commonly used control systems. It should offer the ability to be connected via Profinet, EtherNet/IP, EtherCAT/SBusPLUS, Modus TCP, EtherCAT CiA 402 or PowerLink CiA 402 as a standard. This type of networking capability offers the end user a more easily managed spare-parts inventory by reducing the number of VFDs, which they would require, based upon the number of different networks used by machines in the facility.”

Standard for harmonic distortion

“Meeting the IEEE 519-2014 standard for harmonic distortion has been a focus for customers for a while now,” says ABB’s Orlikowski. “Previously, this was done using legacy solutions such as external harmonic filters or 18-pulse VFDs, which created additional cost and took up additional floor space. Now some manufacturers are integrating active front-end ultra-low harmonic technology into the VFD itself. This leads to simpler installation of both new and retrofit drives for the customer, as well as the ability to efficiently achieve unity power factor at the VFD, while meeting IEEE 519-2014 requirements.”

Connected controls

“Customers are expecting the same conveniences as other appliances and hardware goods, such as internet-connected doorbells and temperature controls in their VFD panels,” says Robert Pauley, sales manager, ac drives division, at Hitachi.

Integrated motor/VFD

“We see more and more integrated motor solutions, where the VFD and the motor are one and mounted on the machine. Connectivity is essential, and adding Ethernet communication protocols is being integrated to the VFD systems,” says Ocampo of Bosch Rexroth.

Predictive maintenance

“Condition-based monitoring is a more recent trend allowing customers more visibility into the current condition of their equipment,” says Miles Mahaffy, manager of North America Application Development Center at Danfoss. “By monitoring not just the VFD internal devices, but also the connected equipment, end users can plan for maintenance before shutdowns occur based on the actual conditions of their equipment rather than time-based maintenance schedules.”

About the Author

Anna Townshend | Managing Editor

Anna Townshend has been a writer and journalist for 20 years. Previously, she was the editor of Marina Dock Age and International Dredging Review, until she joined Endeavor Business Media in June 2020. She is the managing editor of Control Design and Plant Services.

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