Droop Control Function - YASKAWA Varispeed G7 Series Instruction Manual

Feed Forward Control Structure
The following block diagram shows the speed controller (ASR) and the feed forward control structure.
•
N5-02, N5-03
Frequency
reference
Fig 6.80 Structure of Speed Controller (ASR) and Feed Forward Control
Setting Precautions
When N5-02 (Motor acceleration time) is not properly set, the acceleration time may not increase. The fac-
•
tory setting of N5-02 depends on the Inverter capacity. When the Inverter capacity is different from the
motor capacity, calculate an appropriate acceleration time using the equation given in N5-02 of Chapter 5
User Constants or set the time that corresponds to the motor capacity referring to Factory Settings that
Change with the Control Method (A1-02) (Page 5-90)
When setting the feed forward proportional gain (N5-03), take the inertia of the motor to be equivalent to
•
1. If the speed reference response is slow, increase the feed forward proportional gain (N5-03). If over-
shoot occurs with the actual speed, or if a negative torque reference is output when acceleration is com-
pleted, reduce the feed forward proportional gain (N5-03).
When using the droop control function (i.e., if b7-01 is not set to 0.0), disable feed forward control (i.e., set
•
N5-01 to 0).


Droop Control Function

Droop control is a function that allows the user to set the amount of motor slip.
When a single load is operated with two motors (such as in a crane conveyor), a high-resistance motor is nor-
mally used. This is to use torque characteristics that exhibit proportion movements due to changes in the sec-
ondary resistor to maintain torque balance with the load and overall speed balance with the load.
If droop control is used, a high-resistance motor characteristics can be set for a general-purpose motor.
Torque
T B
Motor B's torque
characteristics
Load balance when using a general-purpose motor
Feed
forward
controller
Speed controller (ASR)
U1-05
Detected speed
(Calculated speed)
The balance of the load is very different with different amounts of slip.
Motor A's torque
characteristics
T A
Load torque
The difference between
T and T is getting larger.
A B
Reference Speed
speed
Fig 6.81 Droop Control Function
U1-45
Torque limit
U1-44
Primary
filter
C5-06
L7-01 to L7-04
(C5-10)
Motor A's torque characteristics
Torque
Motor B's torque characteristics
T A
T B
Reference
speed
Load balance when using a high-purpose motor
Individual Functions
Secondary
current
reference
Load torque
The difference between
T and T is getting smaller.
A B
Speed
6-
145