3–16

“A” Group: Standard Functions

Torque Control Algorithms

The inverter generates the motor output according to the V/f algorithm or the intelligent sensorless vector control algorithm. Parameter A044 selects the inverter algorithm for generating the frequency output, as shown in the diagram to the right (A244 for 2nd motor). The factory default is 02 (intelligent sensorless vector control).

Review the following descriptions to help you choose the best torque control algorithm for your application.

Inverter Torque Control Algorithms

 

00

 

A044

 

V/f control,

 

 

 

 

 

 

 

constant torque

01

 

 

 

Output

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

V/f control,

 

 

 

 

 

 

 

 

 

variable torque

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Intelligent sensor-

02

 

 

 

 

 

 

less vector control

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(iSLV)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Configuring

Drive Parameters

 

 

•The built-in V/f curves are oriented toward developing constant torque or variable torque characteristics (see graphs below).

•Intelligent sensorless vector control (iSLV) calculates an ideal torque vector based on current motor position, winding currents, and so on. It is a more robust and precise control method than the V/f control methods. Using the iSLV mode, the inverter automatically adapts to the electrical characteristics of your motor.

Constant and Variable (Reduced) Torque – The graph below (left) shows the constant torque characteristic from 0Hz to the base frequency A003. The voltage remains constant for output frequencies higher than the base frequency. The graph below (right) shows the general variable (reduced) torque curve. The range from 0Hz to the base frequency is the variable characteristic.

V

A044 = 00

Constant torque

V

A044 = 01

Variable torque

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

Hz

0

 

 

 

 

 

Hz

 

 

 

 

 

 

 

 

 

 

Base

 

 

 

 

 

 

 

 

 

Max.

 

Base

Max.

 

freq.

freq.

 

freq.

freq.

Manual Torque Boost – The Constant and Variable Torque algorithms feature an adjustable torque boost curve. When the motor load has a lot of inertia or starting friction, you may need to increase the low frequency starting torque characteristics by boosting the voltage above the normal V/f ratio (shown at right). The function attempts to compensate for voltage drop in the motor primary winding in the low speed range. The boost is applied from zero to 1/2 the base frequency. You set the

V

 

 

 

 

 

 

 

 

A042 = 5

(%)

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Torque boost

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5%

 

 

 

 

 

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.8Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

30.0Hz f base =

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(%)

 

 

 

 

 

 

 

 

 

 

60Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A043 = 3