High-Performance VFD: Sensorless Vector Control

The published SVC figures

Published figure	Value
AU720 — starting torque (SVC)	150% at 0.25 Hz
AU720 — speed range / stability (SVC)	1:200; ±0.5%
AU720 — output frequency	Low-frequency mode 0–500 Hz; high-frequency mode 0–3,200 Hz
AU720 — overload	150% for 1 min; carrier frequency 0.8–16 kHz auto-adjusted with load
EV510 — starting torque (SVC)	150% at 0.5 Hz (G type)
EV510 — speed range / stability (SVC)	1:100; ±0.5%
EV510 — maximum frequency	Vector control 0–500 Hz; V/F control 0–500 Hz
EV510 — overload (G type)	150% of rated current for 60 s; 180% for 3 s

What sits behind the figures

The AUD32's documentation describes its sensorless vector control as built on motor parameter identification, online estimation and flux estimation. The three numbers above are the published SVC set: starting torque at low frequency, the speed range, and how closely speed holds as load changes (±0.5% in SVC on both series). The AU720 documentation describes its current vector control algorithm as providing strong load capacity and fast response across a wide speed range, with torque limit and control applied automatically in vector mode; the EV510 describes a high-performance current vector control with an instantaneous-stop ride-through function that uses motor feedback energy to keep running through short power dips.

The JT series in the company's platform catalogue (JT300, JT500, JT550, JT580) are vector-control drives in the same performance class — the JT550 is documented with PG-card vector options — and for their model-level ratings, ask with your enquiry. Closed-loop vector control, the mode that adds an encoder, is covered on the closed-loop VFD page; the AU720 page is here.

Reading the figures like an engineer

Three reading notes on the published SVC figures. First, starting torque is printed at a frequency: the AU720 SVC figure is 150% at 0.25 Hz. Second, speed range and precision are separate printed figures: the AU720 SVC documentation prints a 1:200 range and ±0.5% steady-speed precision as two lines of the same table. Third, overload is printed as a time-current pair, per series: 150% for one minute on the AU720; on the EV510 G type, 150% of rated current for 60 s and 180% for 3 s. The figures are printed with the conditions the documentation attaches to them.

Frequently asked questions

What closed-loop figures are published?

The FVC figures published for the AU720, and for the EV510's G type, are: starting torque 180% at 0 Hz, a 1:1000 speed range and ±0.02% steady precision, with ±5% torque control precision published for the EV510. Which control level a given application takes is an enquiry item — state the duty and ask for the control level to be addressed in the quotation. See the closed-loop page.

What does 150% at 0.25 Hz mean in practice?

The AU720's published figure is 1.5 times rated torque at a quarter of a hertz — crawl speed. For a specific machine, state its starting requirement in the enquiry and ask for it to be addressed in the quotation.

Are these figures marketing or specifications?

They are specifications, printed in the series' published specification tables (control characteristics sections of the AU720 and EV510 documentation). For a specific model, ask for its figures to be stated in the quotation.