Encoder Phase Angle; Encoder With Commutation Signals (Ab.servo, Fd.servo, Fr.servo) - Control Techniques unidrive sp Advanced User's Manual

Parameter Keypad and Parameter
structure display x.00
3: Closed-loop vector mode without position feedback with no maximum speed limit
In some applications using closed-loop vector control the maximum speed of the system is above the speed at which the encoder feedback
frequency is too high to be used by the drive. For these type of applications Pr 3.24 should be set to 2 for low speed operation and 3 for high
speed operation. It should be noted that the drive no longer checks that the maximum encoder frequency cannot be exceeded in closed-loop
vector control, and so the user must ensure that Pr 3.24 is set to 3 before the encoder frequency limit is reached.
If the drive encoder lines per rev (Pr 3.34) is set to a value that is not a power of 2 and the drive encoder type (Pr 3.38) is used to select any type
of SINCOS encoder this parameter is forced to zero. This is because the extra processing time required to support the feedback device would not
allow enough time for the closed- loop vector algorithm without position feedback to be executed. It should be noted that if the algorithm without
position feedback is active that the sample rate for 6 and 12kHz operation is reduced from 12kHz to 6kHz (see Pr 5.37).

Encoder phase angle

3.25
Drive modes Servo
Bit SP
Coding
Range Servo
Second motor
Servo
parameter
Update rate Background read
The phase angle between the rotor flux in a servo motor and the encoder position is required for the motor to operated correctly. If the phase angle is
known it can be set in this parameter by the user. Alternatively the drive can automatically measure the phase angle by performing a phasing test (see
Pr 5.12 on page 109). When the test is complete the new value is written to this parameter. The encoder phase angle can be modified at any time and
becomes effective immediately. This parameter has a factory default value of 0.0, but is not affected when defaults are loaded by the user.
The alignment required for zero encoder phase angle (i.e. Pr 3.25 = 0.0) is given below for different feedback devices. Forward rotation of the motor
is produced when Vu leads Vv leads Vw. Although it is not essential, forward rotation of a motor is normally defined as clockwise when looking at the
motor shaft end. When the motor is rotating forwards the motor speed is shown as positive and the position increases.

Encoder with commutation signals (Ab.Servo, Fd.Servo, Fr.Servo)

The alignment required between the no-load motor voltages and the commutation signals for Pr 3.25 = 0 is shown in the following diagram below:
Vv
Vu
Vuv Vvw
180 o 240 o 300 o 0 o 60 o
32768 43691 54613 0 10923 21845 32768
Encoder alignment for zero encoder phase angle
Unidrive SP Advanced User Guide
Issue Number: 7
Parameter Advanced parameter
description format descriptions
FI DE Txt VM DP ND
1 1
0.0 to 359.9 ° electrical
Pr 21.20
Vw
No load phase
voltages
Vwu
No load line
voltages
120 o 180 o Encoder angle
U Encoder commutation
signals (high = U > U)
V
W
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Serial comms
Macros
protocol
RA NC NV PT US RW BU
1 1
Electronic Feature look-
Performance
nameplate up table
PS
1
Menu 3
Closed-loop
59