Parameters
M-Max Series Adjustable Frequency Drive MN04020003E—October 2013 www.eaton.com 107
V/Hz-Characteristic Curve (P11)
The M-Max series frequency inverters operate with a
sinusoidal pulse width modulation (PWM) in the inverter. The
IGBTs are actuated by two V/f-based control procedures that
you can select in parameter P11.8.
P11.8 = 0:
●
Frequency control (Hz)
●
Parallel connection of several motors
●
Large power difference (P
FU
>> P
Motor
)
●
Switching in the output
P11.8 = 1:
●
Speed control (RPM, min
–1
) with slip compensation
●
Single operation (only one motor), maximum one power
rating smaller
●
High torque (requirement: exact motor data for the motor
calculation model)
The V/f characteristic (voltage/frequency characteristic)
represents a control procedure of the frequency inverter in
which the motor voltage is controlled in a specific ratio to the
frequency. If the voltage/frequency ratio is constant (linear
characteristic), the magnetizing flux and the torque behavior
of the connected motor is virtually constant.
In the standard application, the benchmark values for the
V/Hz-characteristic curve correspond with the rated
operational data of the connected motor (see the motor
ratings plate):
●
Cut-off frequency P11.2 = Rated motor frequency
P7.6 = Maximum frequency P6.4
●
Output voltage P11.3 = Nominal motor voltage P7.5
The rating data of the V/Hz-characteristic curve is assigned
automatically and corresponds with the values of parameter
P7.5 (nominal motor voltage) and P7.6 (rated motor frequency).
If you require other values for the V/Hz-characteristic curve,
you must first set parameters P7.5 and P7.6, before you
change the parameters of the V/Hz-characteristic curve
shown here.
V/Hz-Characteristic Curve
PNU ID
Access
RUN Value/Range Description
Factory Setting
(P1.3)
P11.1 108 X — V/Hz characteristic curve 0
0 Linear
The output voltage changes linearly with the output frequency;
from zero to voltage P11.3 with the cut-off frequency P11.2
By defining a minimum frequency (P6.3), a voltage
corresponding with one of the linear characteristic curves is
output
The V/Hz ratio running linearly between zero and the cut-off
frequency remains constant
With parameter P11.6, the voltage value can be raised by
percentages in a linear V/Hz-ratio over the entire manipulating
range
1 Squared
The output voltage changes quadratically with the output
frequency; from zero to voltage P11.3 with the cut-off
frequency P11.2
By defining a minimum frequency P6.3, a voltage corresponding
with one of the quadratic characteristic curves is output. The
V/Hz ratio running quadratically between zero and the cut-off
frequency remains constant
With parameter P11.6, the voltage value can be raised as a
percentage by a quadratic V/Hz ratio over the entire
manipulating range
2 Configurable
In connection with parameters P11.4, P11.5 and P11.6, the V/Hz
ratio and therefore the parameters for characteristic curve
progress can be defined as required
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