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V/f curve diagram – Delta Electronics AC Motor Drive VFD-G User Manual

Page 140

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Chapter 4 Parameters|

Revision July 2008, EG03, SW V1.06

4-89

This parameter is to set V/F curve. If this parameter isn’t set to 00, parameter 01-03 and 01-04

will disable.

Input current of the motor could divide into two orthogonal vectors: magnetic vector and torque

vector. Gap flux, which is produced by Magnetic vector, is in direct proportion with output

voltage of motor. Torque vector produces torque. Torque is in direct proportion with the result

of magnetic vector multiply by torque vector. In theory, if the value of magnet vector is the

same with torque vector (in unsaturated flux condition), the input current is minimum. If motor

loading is unsteady torque loading (loading torque is in direct proportion with speed. For

example, the loading of fan or pump), loading torque is low during low speed, suitable lower

input voltage will decrease input current of magnetic field to lower flux loss and iron loss of the

motor and promote whole efficiency.

When this parameter is set to high power V/F curve and low frequency torque is lower, it is not

suitable for AC drive to accel/decel quickly. If it needs to accel/decel quickly, it is not

recommended to use this parameter.

Frequency

%

0

20

40

60

80

100

10

20

30

40

50

60

70

80

90

100

Voltage%

01-02

01-01

1.5 power curve

1.7 power curve

2 power curve

3 power curve

V/F Curve Diagram