Detent torque compensation

NAVIGATION: Closed-loop control > Torque control > Detent torque compensation

Detent torque compensation

In order to compensate for detent torques (caused by non-sinusoidal EM curves), the torque-forming q-current is entered in a table and "taught-in".
After elimination of the offsets (compensated table), the q-current is inverted and fed-in as the pre-control value of the control.

The compensation function can be described by means of compensating currents (q-current, scope signal "isqref_comp") dependent on a position (electrical angle, scope signal "epsRS"). A "teach-in" is used to import the values into a table. With parameter P 0382 CON_TCoggComp the method to be used is selected:

OFF(0), switched off
EPSRS(1), compensation referred to electrical angle
(250 values).
ABSPOS(2), compensation referred to a freely definable position (4000 values).
EPMS(3), compensation referred to one mechanical revolution (250 values).

The interpolation between the table values is linear. The characteristic is not saved automatically; it must be saved manually. The progress of the teach process and the compensation can be tracked on the scope. The signal 55_isqCoggingTeach indicates the momentary output value of the teach table during teach mode, while 56_isqCoggingAdapt contains the momentary value from the compensation table.

Vorgehensweise: Populate table (teach EPSRS)

Open manual mode window
Speed control setting (set high rigidity, for smooth running)
Set parameter P 0385 CON_TCoggTeachCon to "TeachTab(1)" for EPSRS.
Start control
Run motor at low speed (approx. 1 rpm), wait at least one motor revolution.
Set parameter P 0385 CON_TCoggTeachCon to "CalCorrTab(3)" for EPSRS. This imports all values into the compensation table
P 0380 CON_Add Tab.
Stop control
With P0382 CON_TCoggComp = (1)EPSRS activate the process.
Save device data

Vorgehensweise: Populate table (teach ABSPOS)

Open manual mode window
Speed control setting (set high rigidity, for smooth running)
Set parameter P 0385 CON_TCoggTeachCon to "TeachTab(2)" for ABSPOS.
Parameter P 0442 CON_TAB_PosStart:Define start position
Parameter P 0443 CON_TAB_PosDelta: Define position delta: Start position +(position delta*4000)=end position
Parameter P 0445 CON_TAB_TeachDir: Define direction of rotation: (pos-/neg-/both-direction)
Start control
Move the motor at low speed (approx. 1 rpm) until parameter
P 0440 CON_TAB_TabIndex > 4000 (table ABSPOS is not visible).
Set parameter P 0385 CON_TCoggTeachCon to COMPTab(5) for ABSPOS. This imports all values into the compensation table.
Stop control
With P0382 CON_TCoggComp = (2)ABSPOS activate the process.
Save device data

Vorgehensweise: Teach-in (teach EPMS)

Open manual mode window
Speed control setting (set high rigidity, for smooth running)
Set parameter P 0385 CON_TCoggTeachCon to "TeachTab(6)" for TeachEPMS.
Start control
Run motor at low speed (approx. 1 rpm), wait several motor revolutions.
Set parameter P 0385 CON_TCoggTeachCon to "CalCorrTab(3)". This imports all values into the compensation table
P 0380 CON_Add Tab.
Stop control
With P0382 CON_TCoggComp = (3)EPMS activate the process.
Save device data

Parameters

P. no.	Parameter name	Function
P 0380	CON_TCoggAddTab	Taught-in values (EPSRS)
P 0382	CON_TCoggComp	Selection of process
(1)	EPSRS	Compensation referred to the electrical angle; example – three-pole pair motor: The table in P 0380 CON_TCoggAddTab is populated three times within one mechanical motor revolution. The compensation is effected with the averaged table values.
(2)	ABSPOS	Compensation referred to a freely definable position.
(3)	EPMS	Compensation referred to one mechanical revolution
(4)	ENCPOS	Compensation referred to one revolution of the encoder
P 0385	CON_TCoggTeachCon	Selection of teach function
(1)	TeachTab(1)	Activation of Teach function EPSRS
(2)	TeachTab(2)	Activation of Teach function APSPOS
(3)	CalcCorTab(3)	Calculation of compensation
(4)	RESET(4)	Reset table values
(5)	COMPTAB(5)	Calculation of compensation APSPOS
P 0440	CON_TAB_TabIndex	Compensation table: Index
P 0441	CON_TAB_TabVal	Compensation table: Actual
P 0442	CON_TAB_PosStart	Compensation table: Start position
P 0443	CON_TAB_PosDelta	Compensation table: Position delta
P 0445	CON_TAB_TeachDir	Compensation table: Direction of rotation Teach mode
P 0446	CON_TAB_OutVal	Compensation table: Output value

Tabelle: Detent torque compensation