3–13

L100 Inverter

Torque Control Algorithms

The inverter generates the motor output according to the V/f algorithm selected. Parameter A_44 selects the inverter algorithm for generating the frequency output, as shown in the diagram to the right. The factory default is 00 (constant torque).

Inverter Torque Control Algorithms

A44

V/f control,

00

constant torque

Output

Review the following description to help you

V/f control,

01

choose the best torque control algorithm for

variable torque

 

your application.

 

 

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

Constant and Variable (Reduced) Torque – The graph below (left) shows the constant torque characteristic from 0Hz to the base frequency A_03. 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

A_44 = 00

Constant torque

V

A_44 = 01

Variable torque

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

Hz

0

 

 

 

 

 

Hz

 

 

 

 

 

 

 

 

 

 

Base

Max.

 

Base

Max.

 

freq.

freq.

 

freq.

freq.

Torque Boost – The Constant and

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

V

 

 

 

 

 

 

 

 

A_42 = 11

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Variable Torque algorithms feature an

100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

adjustable torque boost curve. When the

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Torque boost

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

motor load has a lot of inertia or starting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

friction, you may need to increase the low

11.8%

 

 

 

 

 

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

frequency starting torque characteristics

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

by boosting the voltage above the normal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

V/f ratio (shown at right). The boost is

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

applied from zero to 1/2 the base

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.0Hz 30.0Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

f base =

frequency. You set the breakpoint of the

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(%)

 

 

 

 

 

 

60Hz

 

A_43 = 10

 

 

 

 

 

 

boost (point A on the graph) by using

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

parameters A_42 and A_43. The manual boost is calculated as an addition to the standard straight V/f line (constant torque curve).

Be aware that running the motor at a low speed for a long time can cause motor overheating. This is particularly true when manual torque boost is ON, or if the motor relies on a built-in fan for cooling.

Parameters Drive

Configuring