How to Achieve Optimal Motor Flux with VFD Technology and WEG

WEG developed this Optimal Flux solution to address the needs of the broader constant torque AC VSD market. Specifically, to satisfy applications with +/-0.5% regulation without an encoder, and with a CT speed range greater than 10:1 (less than 100:1 is required).

Optimal Flux allows the operation of certain WEG motors over speed ranges approaching 1000:1 without thermal damage and closed loop feedback from a motor-mounted encoder.

As each 10°C of temperature reduction typically doubles motor life, the 11% reduction in operating temperature (compared with non-Optimal Flux Control VFD) means motors also last twice as long.

Cutting your losses

Most heat in motors is the result of I²t losses. If motor current can be reduced even slightly, the losses are noticeably reduced.

Variable torque loads do this because they need less torque (and therefore less current) as their speed is reduced. Constant torque loads, on the other hand, may require full torque even at low speeds. So reducing the current to reduce losses isn’t feasible because it reduces torque.

However, with the design characteristics of the WEG motor loaded into the CFW11 VFD, the optimal flux control algorithm increases motor flux slightly at low speeds. This allows the same torque to be developed at lower current.

The result? The WEG VFC can optimise motor flux at low speeds, simultaneously producing fill torque and minimising motor losses.