VFDs: Moving Toward Intelligent Controllers

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Rapid advancements in technology are continuing to alter the way we view the world. Over the past few hundred years we have transitioned through several different industrial revolutions and gone from work performed by steam, water, or horsepower to electrical motors. Looking back half a century, process control primarily focused on variable DC, complicated multi-pole motors, or many other mechanical and electrical variations. To increase efficiency and performance, industries have since transitioned to variable speed three-phase motors.

This has been made possible with pulse-width modulation (PWM) technology that provides variable voltage and frequency to operate electrical motors based on need, rather than at a fixed speed. Furthermore, through intelligent design, we have been able to integrate feedback loops to help increase performance and provide more efficiency.

Today, the variable frequency drive comes in many different variations — from simple volts/hertz machines to more advanced, high-performance devices that have secondary functions and features integrated into their control structure. VFDs now have the capacity to utilize external sensors and monitor more aspects of a process. Further, they can be connected into local or remote monitoring systems to have data logged and trigger warnings when performance appears abnormal.

In essence, these newer intelligent controllers can provide critical data about themselves, their connected motors, or transfer information from other sensors to provide a more holistic picture about the integrity of the process. For a building, plant, or other operation, this frees up critical staffing resources to focus on other tasks, and only attend to problems or maintenance as they arise. 

Intelligent capabilities also reduce the need for multiple controllers as functions are now being integrated into a single module, reducing space, costs, and complexity.

Yet, many of our core systems today are often accepted to just work as-is, without consideration for the possibilities yielded by newer, more efficient technologies. Existing equipment typically is on regular maintenance programs, the cost to operate is relatively fixed, and it is left to run unless and until it fails. Further, many of these systems are operating in a digital means, either fully on or off.

Intelligent controllers for HVAC

By applying intelligent controls to a building’s HVAC system, through new units or via retrofits, users now have more opportunities to improve both energy and lifecycle efficiency for the entire process. Take, for example, the addition of pressure sensors across air filters. This technology can intelligently advise when a filter needs to be changed based on the filter’s integrity rather than at a predefined maintenance interval. Knowing when to change a filter based on need can prevent the extra operating costs that occur when a system uses partially blocked filters or when filters are changed prematurely.

Further, integrated condition-based monitoring for motors can continuously check the integrity of the motor windings and provide alerts before catastrophic failures occur. And because these units are often located in low-traffic areas, the addition of vibration sensors can help to detect problems in either the motor, fan, or pump.

Ultimately, this data can be fed back into the VFD and then distributed throughout the building’s automation network. It can quickly trigger warnings or alerts about potential problems and notify maintenance staff before a severe issue arises.

Intelligent controllers for water and industry

As part of our most critical infrastructure, how we manage the supply and treatment of water is essential to daily life. Many water and wastewater facilities are small and spread out, with minimal observation. More advance technologies today provide ways for operators to remotely manage and monitor these facilities. In fact, there could be several monitoring devices located onsite or near the electric motors which could also deliver data into the VFD.

With the growth of IoT systems, some VFD manufacturers have the capacity to integrate remote monitoring systems that, through an internet connection, are then able to feed information back to the cloud. This can allow users to remotely check in on their equipment and even quickly diagnose problems. Further, remote monitoring can be set up so that external sensors are integrated into the VFD to provide auxiliary information about other aspects of the system such as temperature, pressure, and tank levels.

If an issue were to arise for which outside support was required, the cloud data could easily be shared with VFD technical support teams who could read and interpret it.

This can mean faster dispatch of the resources required to address the problem, reducing the costs and time for diagnosis trips to the site, especially for remote locations.

As we continue to move into a world characterized by bold energy transformation, new applications for VFDs beyond simple motor controls are becoming more relevant and impacting the way we approach systems design. In fact, the same VFD components are now able to perform DC-DC conversion with a few ancillary parts, allowing users to connect batteries or capacitors into VFDs, so that they can continue to run, at least for a few minutes, during a brownout or power failure.

Further, DC-DC converters can store regenerative energy, such as on a lift when lowering. Other applications are utilizing PWM technology to push or pull energy from the grid with an Active Front End. It is even being extended to grid interactive inverters that have the capacity to store energy in batteries for peak power shaving or ride through during brownouts or a grid failure. Combining all these across a DC power network enables users the opportunity to manage multiple energy sources such as wind, solar and storage.

As these intelligent technological advances are still new to industries, we must continue to challenge ourselves on how we utilize energy to perform work. It is important to find the right partners to help unlock new efficient solutions that not only save energy but are ready to help support the ongoing transformation of the energy sector.

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