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HVAC Drive H300 135
Issue Number: 3
Date Format (00.038) selects the display style for Date (00.034), Timer 1
Start Date (09.035), Timer 1 Stop Date (09.037), Timer 2 Start Date
(09.045), Timer 2 Stop Date (09.047), and for the trip time stamping date
parameters (10.041, 10.043, 10.045, 10.047, 10.049, 10.051, 10.053,
10.055, 10.057 and 10.059) when displayed on a keypad connected to
the drive. The format selection made in this parameter does not affect
the value of these parameters if they are read using comms or by an
applications program.
If Date Format (00.038) is 0 then standard format is used and the date is
displayed on the keypad as dd.mm.yy and if Date Format (00.038) is 1
then US format is used and the date is displayed on the keypad as
mm.dd.yy.
6.3.8 Additional parameters for RFC-S sensorless
control
If sensorless mode is being used and is active (i.e. Sensorless Mode
Active (03.078) = 1) and the motor speed is below Rated Speed (00.019)
/ 10 then a special low speed algorithm must be used to control the
motor. RFC Low Speed Mode (00.040) is used to select the algorithm to
be used.
0: Injection
A high frequency signal is injected into the motor to detect the motor flux
axis. This can be used in a similar way to operation with position
feedback except that for the drive to remain stable the speed controller
bandwidth may need to be limited to 10 Hz or less and the current limit
may need to be limited (see Low Speed Sensorless Mode Current
(00.041)).
1: Non-salient
If the ratio Lq/Ld < 1.1 on no load then the injection mode cannot be
used and this mode should be used instead. This mode does not provide
the same level of control as injection mode and has the following
restrictions:
• Speed control is possible, but not torque control.
• Spinning start is not possible and the motor must start from
standstill.
• Below Rated Speed (00.019 / 10 it will not be possible to produce
more than approximately 60 % to 70 % of rated torque.
• There may be some movement of the motor shaft in either direction
as the motor starts.
• It is not possible to measure the motor inertia using auto-tuning with
Auto-tune (00.024) = 4.
• Normally the ramp rate should not be slower than 5 s/1000 rpm
when operating in the region below Rated Speed (00.019) / 10.
• This mode is not intended to control the motor for prolonged periods
below Rated Speed (00.019) / 10, but is intended to allow the motor
to be started from standstill to run outside the low speed region.
• This mode is not intended to allow motor reversals. If the direction
does need to be reversed, the motor should be stopped and any
oscillations must die away, before the motor is restarted in the other
direction.
Low Speed Sensorless Mode Current (00.041) defines a current applied
in the motor d axis to aid starting. The default value is suitable for most
motors with a load of up to 60% rated torque. However, in some
applications this level may need to be adjusted.
2: Current
This method, which applies a rotating current vector at the frequency
defined by the speed reference, can be used with any motor with no
saliency or moderate saliency. It should only be used with motors where
more of the torque is produced in conjunction with the magnet flux rather
than from saliency torque. This mode does not provide the same level of
control at low speed as injection mode, but is easier to set up and more
flexible than "Non-salient" mode. The following should be considered:
1. Only speed control can be used when low speed mode operation is
active.
2. A current specified by Low Speed Sensorless Mode Current
(00.041) is applied when low speed mode is active. This current
should be sufficient to start the motor with the highest expected load.
If the motor has some saliency with no-load applied, and a suitable
saturation characteristic, the drive can detect the rotor position and
apply the current at the correct angle to avoid starting transient. If
the motor is non-salient as defined by the conditions for Inductance
trip then the drive will not attempt to detect the rotor position and the
current will be applied at an arbitrary angle. This could cause a
starting transient if the level of current applied is high, and so Low
Speed Sensorless Mode Current (00.041) should not be set to a
higher level than necessary. To minimise the movement as a result
of applying the current, it is increased over the period defined by
Sensorless Mode Current Ramp (05.063) in the form of a squared
characteristic (i.e. it is increased with a low rate of change at the
beginning and the rate of change is gradually increased).
3. It is not possible to measure the motor inertia using auto-tuning with
Auto-tune (00.023) = 4.
4. As the level of current when low speed mode is active is not
dependent on the applied load, but is as defined by Low Speed
Sensorless Mode Current (00.041), and so the motor may become
too hot if low speed mode is active for a prolonged period of time.
5. Generally Low Speed Sensorless Mode Current (00.041) should be
set to a level higher than the expected maximum load, and can be
set to a much higher level than the load if the saliency and saturation
characteristic allow the position of the rotor to be detected on
starting. However, Low Speed Sensorless Mode Current (00.041)
should be matched more closely to the expected load under the
following conditions: the load inertia is high compared to the motor
interia, or there is very little damping/loss in the load system, or
where the q axis inductance of the motor changes significantly with
load.
3: Current no test
The "Current" method is used, but no attempt is made to determine the
position of the rotor before applying the current. This can be selected for
example, if the motor does not have a suitable saturation characteristic
to allow the rotor position to be determined during starting, or if faster
starting is required. The initial current vector angle will be at an arbitary
position with respect to the actual rotor position. As the vector sweeps
round it must make the rotor start to rotate. If the ramp rate is too high
the rotor may not keep up with the current vector and the motor may not
start. If this is the case then the ramp rate should be reduced and/or the
current used to start the motor should be increased.
00.038 {06.020} Date Format
RW Txt US
OL
Ú
Std (0)
or
US (1)
Ö
US (1)RFC-A
RFC-S
00.040 {05.064} RFC Low Speed Mode
RW Txt US
OL
Ú Ö
RFC-A
RFC-S
Ú
Injection (0),
Non-salient (1),
Current (2),
Current No Test (3)
Ö
Non salient (1)
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