ID34243 'Offset commutation'

Sphere of action:

DRIVE

Default value:

0

Access:

READING / WRITING

Scale:

 0

Temporarily changeable:

YES

Unit:

Increments

Data length:

2 byte

Min. value:

0

Signed:

NO

Max. value:

65535

Format:

DEC

    

List:

NO

    

 

 WARNING

Risk of injury from uncontrolled movements of the motor shaft

If the offset is entered incorrectly, the motor is not controllable and can carry out uncontrolled movements as soon as the controller enable is set!

With 'Initial program loading' the offset is reset to the default value of 0. A previously determined commutation offset is lost. There is no remanent storage in the encoder.

Steps to prevent:

  • Check the entered offset before setting the controller enable.
  • Takes precautionary measures to ensure that no persons are in the total possible range of movement of the motor when the controller enable is set for the first time after the input of the offset.

 

The ID34243 'Offset commutation' is calculated in the run-up with the commutation angle stored in the encoder.

The 'Offset commutation' is added to the actual commutation angle of the encoder.

If the motor negation bit ID32773 'Service bits' bit 16 is set, the commutation offset is subtracted from the commutation angle.

Only positive values in the range 0 - 65535 [increments] can be specified as 'Offset commutation'.

The value 65535 corresponds to a displacement by one mechanical revolution of the motor (360°).

 

Areas of application:

Foreign motors where the determination of the commutation angle deviates from the method by AMK.

Advantage:

With 'Offset commutation', the commutation angle of the foreign motor can be adapted to the AMK inverter, without changing the manufacturer-specific value in the encoder.

The 'Offset commutation' works for the following encoder types EnDat and Hiperface (AMK designations E, F, S, T, P, Q, U, V).

 

Another area of application is the 'fine tuning' of the commutation angle. An existing deviation from the optimum commutation angle can be compensated by small offset values.

 

 

Example: Calculation of the commutation angle from offset commutation and the encoder position

ID32831 'Commutation angle' from encoder position: 451 increments

Example

Parameter

Value

1

ID32773 'Service bits' Bit 16

ID34243 'Offset commutation'

ID32831 'Commutation angle'

0

0 [Increments]

451 [Increments]

2

ID32773 'Service bits' Bit 16

ID34243 'Offset commutation'

ID32831 'Commutation angle'

0

13000 [Increments]

13451 [Increments]

3

ID32773 'Service bits' Bit 16

ID34243 'Offset commutation'

ID32831 'Commutation angle'

1

0 [Increments]

65085 [Increments]

4

ID32773 'Service bits' Bit 16

ID34243 'Offset commutation'

ID32831 'Commutation angle'

1

13000 [Increments]

52085 [Increments]

Example: Compensate errors in the commutation angle

Mechanical motor revolution (360°)

The electrically-aligned synchronous motor shows e.g. a commutation angle of ID32831 = 2350 increments (angle error). To compensate this value to 0, the commutation offset is calculated as follows:

Offset commutation

= Commutation angle - Angle error

= 65536 Increments - 2350 Increments

= 63186 Increments

Check:

Commutation angle

= Commutation offset + Commutation error

= 63186 Increments + 2350 Increments

= 65536 Increments → Correspond the modulo value 0