PowerTec DFS-1 manual Maximum Motor Speed, Encoder Pulses PER Revolution

Models: DFS-1

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0000h Normal current limits (motor current not limited at a lower level)

0001h Motoring torque setpoint (motoring current to be limited at a lower level)

0002h Regenerative torque setpoint (regenera- tive current to be limited at a lower level)

0003h Horsepower setpoint (the product of motor current and motor speed is limited)

0004h through 000Fh available for future use

When in the normal mode, the current in the motor is not controlled below current limit.

If one of the modified operational modes is chosen, the torque/horsepower setpoint is selectable in one of three places:

1.Analog Input #1 (must be set up in parameter #17)

2.Analog Input #2 (must be set up in parameter #21)

3.The Set Application Mode (8F) Command via communications

If one of these three setpoints is not present, the setpoint defaults to the appropriate current limit level.

6.MAXIMUM MOTOR SPEED

USE PARAMETER #6 TO SET THE ABSOLUTE MAXIMUM MOTOR SPEED.

RANGE OF VALUES: 0000 0001h to 0000 2710h 1 TO 10,000 (decimal)

Default Value: 0000 06D6h

1750 (decimal)

The maximum motor speed parameter is set directly in Revolutions Per Minute (RPM) once the Encoder Pulses Per Revolution (PPR) is set in parameter # 7. If the incorrect PPR is set in param- eter #7, the maximum motor speed will not be correct and the motor may overspeed or not be able to go fast enough.

The maximum motor speed is normally the number given on the nameplate of the motor. This number may be set higher than the motor nameplate in some situations because the Brushless DC motor is capable of some overspeed with light loads.

This parameter may be set to a value which is lower than the motor’s base speed in cases where it is not desired to use the full speed of the motor.

7.ENCODER PULSES PER REVOLUTION

USE PARAMETER #7 TO ESTABLISH THE PULSE FEEDBACK RATE FROM THE MOTOR. RANGE OF VALUES: 0000 0001h to 0000 4E20h

1 TO 20,000 (decimal)

Default Value: 0000 0078h

120 (decimal)

This parameter tells the DFS-1 the resolution of the encoder in Pulses Per Revolution (PPR). This is normally four times (4X) the rate of one channel of the motor’s encoder.

Motors from the 42 frame through the 259T frame have a 30 PPR, two channel, quadrature internal encoder. For these motors using the internal encoders the parameter should be set to 120 PPR.

Motors from 287TZ through 5010ATZ have an internal 60 PPR, two channel, quadrature encoder. The parameter for these motors using the internal encoders should be set to 240 PPR.

External encoders may have almost any PPR rate, and they must have two channels in quadrature (the channels have the same pulse rate, but they are 90° out of phase with each other). The pulse rate will be on the ENCODER nameplate.

Encoders with higher pulse rates are normally used to obtain lower speeds and/or finer resolution of motor shaft position. The most common external encoder on POWERTEC motors is a 600 PPR, two channel, quadrature optical encoder. For this encoder the PPR in this parameter will be 2400.

For other encoders, multiply the pulse rate for one channel (the usual number given on the name- plate) by four and enter that number in this param- eter.

This parameter may not be changed while running. Attempting to change this parameter while running will result in the effect being delayed until the next time a setpoint command is given or until the control is stopped. Changing this number will drastically affect the calibration of the system.

(Also see Parameter 46)

Revised 7/95

DFS-1 Manual

Page 21

POWERTEC Ind. Corp.©

 

 

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PowerTec DFS-1 manual Maximum Motor Speed, Encoder Pulses PER Revolution