Optimizing Machine Performance with Variable Frequency Drives

In the competitive landscape of machine design, engineers in food, pharmaceutical and manufacturing sectors face the challenge of creating machines that deliver precision, reliability and efficiency. Modern variable frequency drives (VFDs) are pivotal in achieving these goals. By integrating VFDs, instead of basic soft starters and fixed speed motors, machine designers can unlock significant operational advantages, from energy savings to enhanced operational control.

VFDs are essential for machine design and choosing the right one can impact performance and specific benefits in these critical industries.

Precision Control for Industry-Specific Applications

VFDs provide machine designers with the flexibility to fine-tune motor operation, leading to better overall performance, enhanced reliability and reduced cost. The added benefits of a simpler three-phase motor also benefit the user with greatly enhanced mechanical reliability. Single-phase motors require starting mechanisms, centrifugal switches and capacitors. There are many differences between markets. Some of the considerations unique to them are:

Food processing. In mixers, extruders, and conveyors, VFDs deliver precise speed control to maintain consistent rates of production. In addition, VFDs ensure uniform dough mixing or sauce blending by adjusting torque to handle viscosity changes. Changes in torque can also trigger events based on sensing smooth operation or torque levels.
Pharmaceutical manufacturing. VFDs enable precise control in granulators, tablet presses and packaging lines, where exact speeds are required to show adherence to validated operations. For improved operations, vibration control features minimize mechanical stress, ensuring tight tolerances for high-precision dosing and packaging.
General manufacturing. In CNC machines, robotic arms and assembly lines, VFDs optimize spindle speeds and motion control, accommodating diverse materials and production rates. Advanced sway control for material handling systems enhances safety and precision in automated warehouses.

With VFDs, designers can develop machines that integrate perfectly into diverse production environments. This enhances both new designs and retrofits—without requiring extensive system overhauls. Because VFDs are available in a variety of voltage and power ratings, they are easy to integrate into existing machines.

Mitsubishi Electric AC drives or VFDs — A grouping of Mitsubishi Electric’s AC drives or variable frequency drives (VFDs).

Benefits of VFD-Based Motor Controls

VFDs elevate machine performance by enabling precise, responsive motor control. This control can be set manually, through interfaces on the VFD or auxiliary controls connected to the VFD, and programmatically through connections to programmable logic controllers (PLCs). Key benefits include:

Smooth startups and reduced wear. Soft-start capabilities minimize inrush currents at startup and mechanical stress on motors, belts and gears. The minimized stress on equipment extends the lifespan of the motor and the equipment it interacts with. In food processing, this reduces wear on conveyor belts handling delicate products that would topple or shift during a rapid start. In pharmaceuticals, it lets the machine designer choose the optimal speeds to reduce stresses in high-speed packaging systems.
Vibration and noise reduction. Operating motors at optimal speeds reduces vibration and noise, which supports machine longevity and reliability. In pharmaceutical cleanrooms, the use of sealed three-phase motors supports compliance with strict environmental standards. In manufacturing, the combination of three-phase motors and VFDs enables precision and torque control for tight-tolerance machining applications.
Specialized mechanical functionality. VFDs can provide advanced features such as clog prevention when combined with centrifugal pumps. By monitoring changes in motor torque or power consumption, the VFD can detect signs of a potential clog. The VFD then can trigger a reversal cycle at the time, or on schedule, to maintain performance. Sway control is also available in material movement applications.
Wealth of operational data. When connected to automation systems through a communication protocol such as MODBUS, VFDs can deliver data such as power use; the number of starts, stops, trips and anomalous operations; and more.

Energy Efficiency: A Competitive Edge

Energy efficiency should always be a priority in any industry—not only are environmental concerns important, but rising costs of electricity need to be considered. VFDs deliver significant savings by aligning motor output with process demand. Smarter machines utilizing the adaptability of VFDs have a clear advantage. This includes:

Load matching for power savings. In power-heavy applications, VFDs can reduce motor speed by 20% and cut energy use by as much as 50%. Think of applications like food processing with pumps or extruders or the air distribution fans in pharmaceutical HVAC systems as excellent applications. These energy-intensive applications—e.g., refrigeration in food plants, air handling in cleanrooms—benefit from avoiding major power reductions.
Elimination of inefficiencies. When VFDs replace wasteful mechanical controls like throttling valves in food processing or dampers in pharmaceutical HVAC, energy use is optimized. For example, VFD-controlled pumps—like those used in beverage production—adjust flow precisely, to avoid any over-pumping and thus loss of energy.
Regenerative energy recovery. In material handling applications, VFDs can recover energy during braking operations and send it back into the system. This increases efficiency and reduces costs. Some examples of applications are high-speed conveyors or cranes.
Idle reduction. VFDs enable machines to ramp down or stop during idle periods between batches or just when production rates are slowed due to downstream conditions. For instance, a food processing plant retrofitting VFDs on mixers and pumps could achieve 30-50% energy savings. These savings align with sustainability goals, enhancing the marketability of VFD-equipped machines.

Seamless Integration for Advanced Machine Control

VFDs are designed for easy integration into modern machine control systems, offering robust connectivity options that cater to the automation needs of various industries. The protocols offered vary so that a VFD may be inserted into applications from various automation suppliers.

Electrical connections for local control. VFDs feature intuitive interfaces for local control panels, including digital inputs for start/stop commands, analog inputs for speed adjustments and safety inputs like emergency stops. In manufacturing environments, shielded cables ensure reliable operation in high-EMI environments. Temperature sensors can enable a VFD to monitor and then react to motor conditions.
Communication protocols for automation. VFDs support protocols like Modbus RTU, EtherNet/IP, CC-Link and BACnet. This enables seamless integration with PLCs and other control systems. In applications for pharmaceutical plants, Ethernet with TSN works well for real-time control in high-speed packaging. For food and pharma facilities, BACnet supports HVAC automation. CC-Link and EtherNet/IP are ideal for manufacturing, facilitating scalable, high-bandwidth networks for motion control systems.

Connectivity options like the applications described allow designers to create machines that integrate effortlessly into Industry 4.0 environments, supporting real-time monitoring and predictive maintenance.

Powering Precision and Efficiency in Machine Design

For machine designers in food, pharmaceutical and manufacturing markets, VFDs can provide just the thing for precision, reliability and efficiency. They offer tailored control for a variety of applications such as mixers, tablet presses and packaging machines. This ensures compliance with industry standards while optimizing performance.

VFDs can empower designers to develop innovative and cost-effective machines to meet the goals of modern factories and digitalization. Not to overlook the impressive energy savings, they can integrate well with automation and control systems. As industries prioritize sustainability and operational excellence, VFDs stand as a foundation of machine design, driving efficiency and competitiveness in an evolving industrial landscape.

This article was submitted by Roy Kok, senior partnership and alliance specialist, CC-Link Partner Association.