Elmo HARmonica, HARSFEN0602 software manual 108, Encoder parameterization

HARSFEN0602ElmoHARmonicaSoftwareManual PRELIMINARYDRAFT

hardly noticeable in low speed, significantly looses motor torque at high speed.

If Hall sensors not present, and if the commutation is performed using an incremental encoder, then upon motor start the Harmonica must first find the electrical direction of the motor.

If digital Hall sensors are not present (CA[20]=0), then at motor on, a commutation search is made. The commutation search is described in the section "Commutation search".

The following seven parameters describe the Hall sensors:

CA[1]	The polarity of the A digital Hall sensor. 1 for active high, 0 for active low.
CA[2]	The polarity of the B digital Hall sensor. 1 for active high, 0 for active low.
CA[3]	The polarity of the C digital Hall sensor. 1 for active high, 0 for active low.
CA[4]	The actual Hall sensor connected to the A Hall connector pin 1 for A, 2 for B and 3
	for C
CA[5]	The actual Hall sensor connected to the B Hall connector pin 1 for A, 2 for B, and 3
	for C
CA[6]	The actual Hall sensor connected to the C Hall connector pin 1 for A, 2 for B, and 3
	for C
CA[7]	The offset of the digital Hall Sensors in encoder units. The range for this parameter
	is [0..CA[18]-1]. This parameter compensate for deviations in the hall sensor
	switching point.
	If no encoder is present, set this parameter to zero.
CA[20]	Digital Hall sensors present.
	0: No digital Hall sensors are connected
	1: Digital Hall sensors are connected.

9.3.4.3Encoder parameterization

Accurate commutation requires high a resolution sensor. Many types of high-resolution sensors exist. The selections available for Harmonica are:

CA[17] Commutation sensor type.

1:Main Encoder

CA[21] Position sensor present

0:No high-resolution commutation sensor. Commutation will be done based on the digital Hall sensors only.

1:The main position sensor shall be used for commutation

The encoder is normally used both for motion feedback and for commutation. As a motion feedback counter, it must count up when the motor go forward in the application sense. As a commutation counter, it must count up when the commutation angle increases.

The above two requirements are not necessarily same, so we need the following two parameters:

CA[16] Encoder direction: Set 0 or 1 so that the encoder will count forward in the desired movement direction.

CA[25] Motor direction: Set 0 or 1 so that with positive torque, the motor will rotate in the direction for which the encoder counts up.

The encoder measures the shaft angle. In order to commutate, we must know the encoder count per an electrical revolution. Normally, the number of encoder counts per motor revolution is an integer (If not, we may not be able to commutate correctly with an encoder...). The number of pole pairs per revolution is always integer. By knowing the encoder counts per mechanical revolution, and by knowing how many pole pairs are within a revolution, the commutation counter can infinitely update without accumulating errors. For linear motors, it is best to set the number of pole pairs CA[19] as the largest number of

108