108
Fig. F5-5 Voltage Control Mode 1
This control mode is widely applied in areas like EPS
power source. The control principle is as showed in
the following wireframe figure.
U*——setting value of P5.13 channel
U1——analog feedback voltage (PT)
PT——electrical quantity transducer
Fig. F5-6 EPS Control Principle
Notice:
Analog feedback channel voltage has a corresponding
relation F6.06~F6.11 with actual voltage, and the
relation is only determined by voltage transducer (PT),
the computational method is as follows:
Hypothetically U*=120%*Ue=456V(AI1)
PT ratio=50 (input AC 0-500V, output DC 0-10V)
When output reaching the target voltage 456V, the
feedback voltage of PT output is
456/50V=9.12V
AI1 upper limit input is 10V, input voltage is 500V, the
ratio to rated voltage value is
500/380=132%
So F6.09 (AI2 input upper limit voltage) can be set as
10.00V, F6.10 (AI2 upper limit corresponding setting)
can be set at 132%.
2: VF fully separated mode, voltage open-loop output
In this mode, output frequency and voltage of
VFD are completely independent. Frequency changes
according to set acc/dec time, voltage is adjust to
target value according to rise/fall time defined by
F5.19, F5.20, as showed in figure F5-7. This control
mode is mainly applied in designing of some
variable-frequency power source.