Closed-Loop VFD: Vector Control with Encoder Feedback

The published FVC figures

Series	Published closed-loop figures
AU720 — FVC	Starting torque 0 Hz/180%; speed range 1:1000; steady precision ±0.02%; overload 150% for 1 min
EV510 — FVC	Starting torque 0 Hz/180% (G type); speed range 1:1000; steady precision ±0.02%; torque control precision ±5%
AU1000 — CLVC	Starting torque 0 Hz/180% (G type); speed range 1:1000; steady precision ±0.02%
AU550	The “close-loop inverter” series named in the platform catalogue — the dedicated closed-loop line; model ratings per enquiry

Encoder options (documented)

The EV510 documentation lists three optional PG (encoder) card types explicitly: a differential input PG card, a rotating transformer (resolver) PG card and an OC input PG card. The AU1000 documents five encoder families: differential, open-collector, resolver, UVW and SIN/COS. Encoder selection is therefore part of the order conversation: state your encoder type (or that one must be supplied) with the enquiry.

The EV510 publishes its FVC starting torque for the G class (180% at 0 Hz); its P class publishes its own vector figures in the same documentation. The AU1000's closed-loop figures are published in its elevator documentation, alongside individualised functions that include slip compensation and torque limits.

Lifts, hoisting and the servo route

• Duties whose specification cites the published FVC figures themselves — starting torque at 0 Hz/180% (AU720; EV510 G type), steady-speed precision of ±0.02% (AU720 and EV510), or the EV510's ±5% torque-control accuracy.
• For lifts and hoisting contexts, see the elevator and crane pages.
• For the PMSM servo route, the LS590 servo system has its own page.

Where none of those apply, the sensorless figures for the same duties are on the high-performance VFD page.

Torque control in the published figures

The published FVC set includes ±5% torque-control accuracy (EV510) alongside the speed figures, and 180% starting torque at 0 Hz on the AU720, and on the EV510 and AU1000 for their G types. Torque limit and control are documented functions of the vector modes. Which of those figures a given installation works to is an enquiry item: state the application data with the enquiry and ask for the applicable figures to be addressed in the quotation.

Fitting the loop: practical notes

The documented card families exist because encoders vary: the EV510 lists three PG card types and the AU1000 lists five encoder families, as set out above. State what encoder is fitted (or that one must be supplied) when you enquire, and ask for the card matching your encoder to be covered in the quotation rather than treated as a second order.

Frequently asked questions

What encoder does the drive need?

The EV510 documents three PG card options — differential input, rotating transformer (resolver) and OC input; the AU1000 documents differential, open-collector, resolver, UVW and SIN/COS encoder support. State your encoder with the enquiry.

AU550 or AU720 in FVC mode?

The AU550 is the catalogue's named close-loop series; the AU720 publishes its FVC figures. For model-level positioning of the two, send your application data with your enquiry and ask for it to be addressed in the quotation.