appendices vacon • 91
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9
9. APPENDICES
In this chapter you will find additional information on special parameter groups. Such groups are:
Closed Loop parameters (Chapter 9.1)
Parameters of Motor thermal protection (Chapter 9.2)
Parameters of Stall protection (Chapter 9.3)
Fieldbus control parameters (Chapter 9.4)
9.1 Closed loop parameters (ID’s 612 to 621)
Select the Closed loop control mode by setting value 3 or 4 for parameter ID600.
Closed loop control mode (see page 61) is used when enhanced performance near zero speed and
better static speed accuracy with higher speeds are needed. Closed loop control mode is based on
"rotor flux oriented current vector control". With this controlling principle, the phase currents are
divided into a torque producing current portion and a magnetizing current portion. Thus, the squirrel
cage induction machine can be controlled in a fashion of a separately excited DC motor.
Note: These parameters can be used with Vacon NXP drive only.
EXAMPLE:
Motor Control Mode = 3 (Closed loop speed control)
This is the usual operation mode when fast response times, high accuracy or controlled
run at zero frequencies are needed. Encoder board should be connected to slot C of the
control unit. Set the encoder P/R-parameter (P7.3.1.1). Run in open loop and check the
encoder speed and direction (V7.3.2.2). Change the direction parameter (P7.3.1.2) or switch
the phases of motor cables if necessary. Do not run if encoder speed is wrong. Program
the no-load current to parameter ID612 and set parameter ID619 (Slip Adjust) to get the
voltage slightly above the linear U/f-curve with the motor frequency at about 66% of the
nominal motor frequency. The Motor Nominal Speed parameter (ID112) is critical. The
Current Limit parameter (ID107) controls the available torque linearly in relative to motor
nominal current.
9.1.1 Note on use of permanent magnet motors (“AC brushless” motors)
Parameter
Magnetizing current
(par. ID612) is not relevant to CL control of these motors.
Suggested values for other CL motor control parameters:
• ID613
Speed control Kp
: much lower value, 10 to 20, for low inertia loads.
• ID617
Current control Kp
= 20 for typical V/f values (eg. 400V/150Hz), values proportional to full
load V/f ratio.
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