Digital Hall sensors

Hall sensors on encoder channel 1

Alongside the resolver and optical encoder standard encoder types, Hall sensors can also be evaluated. The sensor supply at pin 3 is short-circuit proof in both +5 V and 11 V operation.

Pin assignment

Tabelle: Pin assignment for Hall sensor evaluation

Differential track signals

Note that track signals A and B must be fed in as differential signals on X7! When using standard Hall sensors with open-collector outputs, the following adaptation circuit is recommended for each channel:

Bild: Adaptation circuit for standard Hall sensors

Application of a Hall sensor

To use the Hall sensor, it is important to know whether the solenoids are 90° or 120° shaped. The Hall sensor function should first be executed on a scheme of a single pole pair Hall sensor with a 90° offset solenoid. The arrangement of solenoids A and B results in the states from the state table dependent on the magnetic field. They can be visualized using the scope function, producing the pattern diagram.

Bild: AB track of a Hall sensor with state table and pattern diagram

The four possible states from which the offset can result.

State table

Hall pattern signal

Application of the Hall sensor

Vorgehensweise: Parameterizing the Hall sensor function

Setting of the source from which autocommutation is executed. In order to use digital Hall sensors, this parameter must be set to "CH1(1)=Channel 1 (SinCos X7)" P 0520[0] ENC_MCON.

Bild: Encoder selection

Activate encoder activation. In order to use digital Hall sensors, this parameter must be set to "HALL(5)=digital hall-sensor" P 0505[0] ENC_CH1_Sel.
Selection of source for speed control. To close the speed control loop via the Hall sensors, this parameter must be set to "CH1(1)=Channel 1 (SinCos X7)"
P 0521[0] ENC_SCON.
Layout of Hall sensors. From the "2x90(1)=2 x 90°" and "2x120(2)=2 x 120°" settings select the layout applicable to the sensors in use P 0557[0] ENC_CH1_HallLayout (The layout cannot be changed online. The control must always be re-initialized in the event of a change).
The speed filter time P 0 351[0]_CON_SCALC_TF should be adapted from 0.6 ms to 10 ms. The pulses per revolution in parameter
P 0542[0] ENC_CH1_Lines must be set to 1.

Vorgehensweise: Find commutation

Selection of the autocommutation method
For automatic determination of the Hall sensors offset parameter
P 0390[0] CON_ICOM must be set to "HALLSDIGITAL(6)". The offset is determined in three stages:
Alignment of the motor on its d-axis:
P 0392[0] CON_ICOM_Time: Time for alignment in [ms]
P 0393[0] CON_ICOM_Current: Motor current to align the motor

The current should be applied so that one mechanical revolution per second is set.
P 0392[1] CON_ICOM_Time: Time to accelerate to a speed of 1 Hz
P 0393[0] CON_ICOM_Current: Motor current in the rotation phase
Measurement of the offset:
P 0392[1] CON_ICOM_Time: Time for offset measurement while the motor is rotating at 1 Hz. When the time has elapsed, the mean of all measured values is determined and applied as the encoder offset.

If wire break monitoring is activated at high frequencies, the value of P 0551 ENC_CH1_EncObsMin should be decreased.
For correct determination of the offset it must be ensured during the rotation phase that the motor is rotating evenly and without jerking. If it is not, the motor current should be adapted via P 0393[1] CON_ICOM_Current.
If no offset is measured, error message "Error 25-00" is generated. In this case the motor current should be increased during the rotation phase via P 0393[1] CON_ICOM_Current or the wiring should be checked.
Once the encoder offset has been successfully determined, automatic determination of the offset can be deactivated again. To do so, set P 0390[0] to "OFF(0)".

Manual setting for the Hall sensor offset

It would basically not be necessary to determine an offset if the Hall sensor is arranged orthogonally relative to the rotor. As that is not normally the case, the offset must be set manually. In manual setting in VFCON mode, the offset is set so that the electrical angle passes through zero simultaneously with the Hall pattern. If this link has been established, the offset is correctly set. To enable the motor to move without jerking even at low speeds, the PLL phase control must additionally be set so that a good overall result can be attained.

Manual determination of the offset with "VFCON"

Bild: Manual offset determination

When using Hall sensors, the speed recording at low speeds is inexact. Consequently, the angle P 0500 ENC_CH1_ActVal[0] must be amplified by way of the phase control loop PLL (Phased Locked Loop) so that the sawtooth signal of the angle does not fade.

Bild: Phase control loop

Vorgehensweise: Setting for PLL

Gain factor P 0559[0] Kr_PLL
Integral-action time: P 0559[1] Tn_PLL
Angle correction: P 0612[0] ENC_CH1_HALL_EpsCorr_Sel

OFF(0)=function off“ deactivates the angle correction.
CDC(1)=current dependent" effects a current-dependent correction.
SDC(2)=speed dependent“ and "CSDC(3)=current and speed dependent" are not yet implemented at present.

P 0613[0] epsMax indicates the maximum angle correction in degrees.
P 0613[1] eps1, P 0613[2] eps2 and P 0613[3] eps3 are additional correction values applied if the corresponding current
P 0614[0-3] is exceeded.

P 0614[0] currMax indicates the current in Amperes at which the maximum angle correction is to be applied. P 0614[1] curr1, P 0614[2] curr2 and P 0614[3] curr3 are the current values as from which the associated angle corrections
P 0613[0-3] epsX) are to be applied.

P 0615[0] ENC_CH1_HALL_EpsCorr_Dir permits a Hall sensor offset dependent on the direction of rotation to be set which is deducted from the encoder angle when calculating the position. Normally this value can be set to "0". For Hall sensors installed at an oblique angle this offset may be necessary however.

NOTE:

When using Hall sensors, the speed recording at low speeds is inexact. The recommendation is therefore to set P 0745[0] MON_RefWindow to a value ≥100.

If the speed signal is very noisy, it is possible to filter it via
P 0351[0] CON_SCALC_TF.

Example of a good PLL gain:

Bild: PLL gain

NOTE:

With a single pole pair motor, one period of the Hall pattern signal corresponds to one mechanical revolution.

Scope signals

Signal number	Signal type	Signal name	Unit	Icon
0004 [0]	Scope signal	current vector, comp. alpha	A	isalpha
0005 [0]	Scope signal	current vector, comp. beta	A	isbeta
0030 [0]	Scope signal	electrical angle of PWM and current control	pole width	epsFSM
1130 [0]	Scope signal	HALL: Table index (encoder CH1)	-	HALL-PATTERN
1131 [0]	Scope signal	HALL: Angle from table (encoder CH1)	-	HALL-epsVALUE

Tabelle: Assignment of scope signals for setting of the Hall sensor