L_TB1P_IdentMInertia

By means of this FB, the current moment of inertia can be automatically identified. The FB takes over the drive control on request and carries out the identification process.

When the identification run has been completed successfully, the moment of inertia is output via lrMInertiaIdent .

		L_TB1P_IdentMInertia
BOOL	-	xIdent	xBusy	-	BOOL
BOOL	-	xFollowerActive	xDone	-	BOOL
LREAL	-	lrActReelSpeedIn	xError	-	BOOL
LREAL	-	lrActTorqueIn	eErrorID	-	L_IE1P_Error
LREAL	-	lrMaxSpeedIdent	xEnableFollower	-	BOOL
LREAL	-	lrMaxTorqueIdent	lrSetTorqueOut	-	LREAL
LREAL	-	lrFilterTimeSpeed	lrMInertiaIdent	-	LREAL
LREAL	-	lrFilterTimeTorque
LREAL	-	lrFilterTimeReelSpeed

Inputs

Name Data type	Information/possible settings
xIdent BOOL	TRUE	Start identification of the moment of inertia.
xFollowerActive BOOL	Interface to basic "torque follower" function
lrActReelSpeedIn LREAL	Current speed of the motor shaft (actual speed value) Unit: rev/s
lrActTorqueIn LREAL	Current torque (actual torque value) Unit: Nm
lrMaxSpeedIdent LREAL	Maximum speed for the identification of the moment of inertia Unit: rev/s
lrMaxTorqueIdent LREAL	Maximum torque for the identification of the moment of inertia Unit: Nm
lrFilterTimeSpeed LREAL	Filter time constant for the actual speed value Unit: s Initial value: 0.0 (with this value, the filter is not active.)
lrFilterTimeTorque LREAL	Filter time constant for the actual torque value Unit: s Initial value: 0.0 (with this value, the filter is not active.)
lrFilterTimeReelSpeed LREAL	Filter time constant for the speed setpoint Unit: s Initial value: 0.0 (with this value, the filter is not active.)

Outputs

Name Data type	Value/meaning
xBusy BOOL	TRUE	Identification of the moment of inertia is active.
xDone BOOL	TRUE	Identification of the moment of inertia has been completed successfully.
xError BOOL	TRUE	An error has occurred. For details see eErrorID .
eErrorID L_IE1P_Error	If xError = TRUE: Error number for the error that has occurred.
xEnableFollower BOOL	TRUE	The basic function "Torque follower" is activated.
lrSetTorqueOut LREAL	Torque setpoint for the identification of the moment of inertia Unit: Nm
lrMInertiaIdent LREAL	Moment of inertia identified Unit: kgcm ²

Process of identifying the moment of inertia

The basic function "Torque follower" is activated.

The xBusy output changes to TRUE.

If the drive is still coasting, it is waited until the motor has coasted down.

The drive is accelerated to the defined maximum speed with the torque setpoint specified.

When the drive has reached the maximum speed, it is braked to a standstill again with the inverse torque setpoint.

The moment of inertia available is calculated.

At the lrMInertiaIdent output, the value calculated is shown as a physical value in the unit [kgcm ² ].

After a successful identification process, ...

the xBusy output is set to FALSE;

the xDone output is set to TRUE.

The identification is executed according to the following state machine:

State machine for the identification of the moment of inertia

Aborting the identification process of the moment of inertia

If the xIdent input is reset to FALSE, the active identification process is cancelled immediately. Resetting the xFollowerActive input to FALSE also results in the immediate abort of the process.

The xBusy output is reset to FALSE.

The drive is brought to a standstill via quick stop (QSP).

The cause of abort is shown via the eErrorID output.

Smoothing the actual speed signal

If incremental encoders are used, it may be required to filter the actual speed value signal.

The time constant for the filter can be set via the lrFilterTimeSpeed input. A setting of '10 ms' is sufficient in most cases.