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HVAC Drive H300 131
Issue Number: 3
Enter the name-plate value for the motor rated current.
Enter the value from the rating plate of the motor.
This parameter defines the required switching frequency. The drive may
automatically reduce the actual switching frequency (without changing
this parameter) if the power stage becomes too hot. A thermal model of
the IGBT junction temperature is used based on the heatsink
temperature and an instantaneous temperature drop using the drive
output current and switching frequency. The estimated IGBT junction
temperature is displayed in Pr 07.034. If the temperature exceeds
145 °C the switching frequency is reduced if this is possible (i.e >3 kHz).
Reducing the switching frequency reduces the drive losses and the
junction temperature displayed in Pr 07.034 also reduces. If the load
condition persists the junction temperature may continue to rise again
above 145 °C and the drive cannot reduce the switching frequency
further the drive will initiate an ‘OHt Inverter’ trip. Every second the drive
will attempt to restore the switching frequency to the level set in
Pr 00.022.
The full range of switching frequencies is not available on all ratings of
Unidrive M. See section 8.3 Switching frequency on page 161 for the
maximum available switching frequency for each drive rating.
Open-loop
When the drive is enabled with Pr 00.023 = 0, the output frequency
starts at zero and ramps to the required reference. When the drive is
enabled when Pr 00.023 has a non-zero value, the drive performs a
start-up test to determine the motor speed and then sets the initial output
frequency to the synchronous frequency of the motor. Restrictions may
be placed on the frequencies detected by the drive as follows:
RFC-A mode
If sensorless mode is being used then it is recommended that catch a
spinning motor is disabled if the motor will always be stationary when the
drive is enabled as this gives a smooth start and avoids unwanted
transient movement of the motor on starting. If catch a spinning motor is
enabled, but the motor is at standstill or rotating slowly it is likely than
some unwanted movement will occur. This can be reduced by reducing
Magnetising Current Limit (04.049), however if this is reduced too much,
especially with larger motors, and over-current trip may occur on
starting. It is possible, although not likely, that the drive does not
correctly detect the speed of the motor when sensorless control is
active. If this is the case Spin Start Boost (05.040) can be increased to
correct this.
Open-Loop
There are two autotune tests available in open loop mode, a stationary
and a rotating test. A rotating autotune should be used whenever
possible so the measured value of power factor of the motor is used by
the drive.
Autotune test 1:
• A stationary autotune can be used when the motor is loaded and it is
not possible to remove the load from the motor shaft. The stationary
test measures the Stator Resistance (05.017) and Transient
Inductance (05.024) which are required for good performance in
vector control modes (see Open Loop Control Mode (00.014). The
stationary autotune does not measure the power factor of the motor
so the value on the motor nameplate must be entered into Pr
05.010. To perform a Stationary autotune, set Pr 00.024 to 1, and
provide the drive with both an enable signal (on terminal 29) and a
run signal (on terminal 24).
Autotune test 2:
• A rotating autotune should only be used if the motor is unloaded. A
rotating autotune first performs a stationary autotune, as above, then
a rotating test is performed in which the motor is accelerated with
currently selected ramps up to a frequency of Rated Frequency
(05.006) x
2
/
3
, and the frequency is maintained at that level for 4
seconds. Stator Inductance (05.025) is measured and this value is
used in conjunction with other motor parameters to calculate Rated
Power Factor (05.010). To perform a Rotating autotune, set
Pr 00.024 to 2, and provide the drive with both an enable signal (on
terminal 29) and a run signal (on terminal 24).
Following the completion of an autotune test the drive will go into the
inhibit state. The drive must be placed into a controlled disable condition
before the drive can be made to run at the required reference. The drive
can be put in to a controlled disable condition by removing the Safe
Torque Off signal from terminal 29, setting the Drive Enable (06.015) to
OFF (0) or disabling the drive via the Control Word (06.042) and Control
Word Enable (06.043).
RFC-A
There are two autotune tests available in RFC-A mode, a stationary test,
and a rotating test. A stationary autotune will give moderate performance
whereas a rotating autotune will give improved performance as it
measures the actual values of the motor parameters required by the
drive.
It is highly recommended that a rotating autotune is performed
(Pr 00.024 set to 2).
Autotune test 1:
00.020 {05.007} Rated Current
RW Num RA US
OL
Ú
0.000 to
VM_RATED_CURRENT A
Ö
Maximum rated current
(11.060) A
RFC-A
RFC-S
00.021 {05.006} Rated Frequency
00.021 {05.033} Volts per 1000 rpm
RW Num US
OL
Ú
0.0 to 550.0 Hz
Ö
50 Hz default: 50.0 Hz
60 Hz default: 60.0 Hz
RFC-A
Ú
0.0 to 550.0 Hz
RFC-S
Ú
0 to 10000 V / 1000 rpm
Ö
98 V / 1000 rpm
00.022 {05.018} Maximum Switching Frequency
RW Txt RA US
OL
Ú
2 kHz (0), 3 kHz (1),
4 kHz (2), 6 kHz (3),
8 kHz (4), 12 kHz (5),
16 kHz (6)
Ö
3 kHz (1)RFC-A
RFC-S
00.023 {06.009} Catch A Spinning Motor OL and RFC-A
RW Txt US
OL
Ú
Disable (0), Enable (1),
Fwd Only (2),
Rev Only (3)
Ö
Disable (0)
RFC-A
Pr 00.023 Pr string Function
0 Disable Disabled
1 Enable Detect all frequencies
2 Fwd only Detect positive frequencies only
3 Rev only Detect negative frequencies only
00.024 {05.012} Auto-tune
RW Num NC
OL
Ú
0 to 2
Ö
0RFC-A
Ú
0 to 2
Ö
RFC-S
Ú
0, 1, 2, 6
Ö
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