One Drive, Many Destinations: Exploring Servo‑ and Motor‑Drive Roles 

Introduction – Why the Distinction Still Matters

In factory automation, the terms “servo drive” and “motor (or VFD) drive” often describe two very different philosophies of motion control. Servo drives close a feedback loop around position or torque to hit sub‑millimetre repeatability, while a general‑purpose variable‑frequency drive (VFD) regulates speed with enough accuracy for conveyors, fans, or pumps. Yet modern electronics, faster processors, and smarter firmware have blurred the line: a single inverter can now switch personalities with a few parameter changes. The 0.75 kW KEB Combivert F5 07.F5.B3A‑0A0A is a textbook example, able to run open‑loop sensor‑less vector control in the morning and closed‑loop servo control after lunch. Understanding how that flexibility is achieved—and where it pays dividends—helps designers squeeze more value out of every cabinet slot.

Servo vs Standard Drives: A Quick Technical Primer

Classic VFDs modulate the voltage and frequency sent to an induction motor so that shaft speed matches process demand. They rely on slip and scalar control models, good for ±2–3 % speed accuracy. Servo drives, by contrast, treat the motor as part of a tightly coupled electromechanical system. A high‑resolution encoder (or resolver) closes the loop around position, velocity, and torque, allowing the controller to command precise motion profiles, electronic cam tables, or rigid gearing between multiple axes. What makes hybrid units like the F5 attractive is a firmware layer that supports open‑loop V/Hz, sensor‑less vector, encoder vector, and full servo modes in the same hardware envelope.

The 07.F5.B3A‑0A0A—One Chassis, Two Personalities

Housed in an IP20 “B3A” frame, the 07.F5.B3A‑0A0A accepts either single‑ or three‑phase 230 V supplies and delivers 4 A continuous / 8.6 A peak output current—ample for small servo axes, gear pumps, or fractional‑horsepower fans. Its factory firmware unlocks switching frequencies up to 16 kHz, integrated braking chopper, eight programmable digital inputs, and dual analog channels for sensors or potentiometers. Short‑circuit and ground‑fault monitoring, plus SIL‑compliant Safe Torque Off (STO), let the same SKU satisfy both EN 61800‑5‑1 drive‑safety rules and ISO 13849 machine‑safety schemes.

Use Case 1 – High‑Precision Servo on a Cartoning Machine

Switch the drive to encoder vector or “Multi” mode, plug in a 17‑bit absolute encoder, and the F5 becomes a pure servo amplifier. On a pharmaceutical cartoner, push‑rod actuators must insert blister packs within ±0.2 mm to avoid crushed cartons. The drive’s internal electronic cam links push‑rod position to the master conveyor so phases stay locked regardless of line speed. Because the 07.F5.B3A‑0A0A can scan control terminals every 2 ms and update current loops just as fast, it can accelerate the rod, coast, and decelerate to a hard stop 60 times per minute without overshoot.

Use Case 2 – Sensor‑less Vector Control on a Coffee‑Roasting Drum

In a small‑batch roaster, precision is measured in degrees Celsius, not microns. Operators need a rock‑steady 15 rpm at 240 °C to develop sugars, then a burst to 90 rpm for bean cooling. Here, the same drive runs an induction motor with sensorless vector firmware. Rotor flux is estimated from current and voltage alone, eliminating encoders in a dusty, high‑temperature cavity. The wide 0–599 Hz frequency span listed for the unit ensures speed headroom even if roasting profiles change.

Use Case 3 – Regenerative Conveyors in E‑Commerce Fulfilment

Forty‑metre decline conveyors shuttle totes from mezzanine sorters to ground‑floor docks. Each descent is an energy‑positive event, and the F5’s built‑in chopper channels that braking energy back onto the DC bus, where companion drives or a line‑side regen module feed it into the plant grid. Field trials show 12 % net energy savings over drives that dump excess power into resistors. Because regenerative operation is a drive‑level function, it works regardless of whether the attached motor is a servo or a plain squirrel‑cage induction type.

Use Case 4 – Torque‑Controlled Servo‑Pump in Injection Moulding

Servo‑hydraulic retrofits replace inefficient fixed‑displacement pumps with variable‑speed gear pumps. Here, the 07.F5.B3A‑0A0A operates in torque mode, holding oil pressure within ±5 bar during each 4.7 s clamp cycle. The compact 0.75 kW rating is enough because the motor idles during cooling, and the selectable 4/8/16 kHz PWM lets designers trade acoustic noise against efficiency—handy for collaborative cells where human operators stand metres away.

Keys to Switching Roles without Switching Hardware

1. Feedback Flexibility – The drive’s modular control board accepts TTL, HTL, SinCos, or SSI encoders, making it trivial to add positional feedback when upgrading a legacy VFD process to servo accuracy.
2. Control‑Mode Parameter Sets – Up to eight fully independent parameter banks allow “Recipe 1” to be a sensor‑less vector, “Recipe 2” closed‑loop servo, each recalled via a digital input or field‑bus command.
3. Safety Built‑In – STO eliminates external contactors that once differentiated servo cabinets from simple fan panels; a single risk assessment now covers both duties.
4. Energy Strategy – Integrated regen and DC‑bus sharing means one drive can act as an energy sink while another serves as a source, maximising utilisation no matter which mode each axis is running.

Conclusion

The KEB 07.F5.B3A‑0A0A demonstrates how the vocabulary of “servo drive” and “motor drive” is converging. Firmware‑selectable control algorithms, high‑bandwidth power stage, and safety circuitry allow one 75‑millimetre‑wide inverter to roast coffee at dawn, index blisters by noon, and recover conveyor energy before lights‑out—all without leaving its cabinet slot. For machine builders and plant engineers, the takeaway is clear: investing in multifunctional drives reduces spares, eases retrofits, and opens a wider design envelope than locking every axis into a single control philosophy. As the border between precision motion and variable‑speed utility continues to dissolve, drives like the 07.F5.B3A‑0A0A will be the hardware bridges that make the transition seamless.