Page 210 - Root Cause Failure Analysis
P. 210
198 Root Cause Failure Analysis
Per unit
Torque
667 83.3
Speed in Hertz
Figure 16-3 V/Hz drive cannot apply full torque as speed approaches zero.
most cases, the flux-vector inverter will have better response characteristics than the
V/Hz inverter. The feedback logic used in flux-vector inverters provide a more posi-
tive means for both detection and compensation for load variations.
Acceleration Control
Inverters must provide positive speed and torque control over the full operating range
of the controlled motor and system. Inverter speed-control characteristics, especially
2
Torque
1
12 5 10 30 40
Speed (Hz)
Figure 164 Flux vector has limited ability to supply full torque at low speeds.
