Lenze DSD - Manual (Page 68)

7 Applications
7.2 Basic calculations
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Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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7.2 Basic calculations
In this chapter the basic calculations required for ascertaining the requirement of the application
are described. The initial situation results from the calculations which have to be carried out for the
respective application (e. g. travelling drive).
The requirement of the application results from
• The torque required,
• The speed required,
• The power resulting from the two.
7.2.1 Torque
To dimension the drive system correctly, the torque of the application is required. It should be cal-
culated completely for the application, taking the losses (e. g. friction) into consideration. A division
into a dynamic and a stationary component cannot be effected, as the friction partly has an effect
on dynamic components, and to some extent it has not.
For instance, in the case of a spindle, due to the linearly moved masses losses are created with re-
gard to the dynamic forces, and due to the moment of inertia of the spindle the dynamic torques act
on the drive system without losses. Furthermore the losses depend on different factors depending
on the application. It is therefore assumed that the required torque of the application M
app
is given:
[7-1] Equation 1: Total torque of the application

Tip!
The equation for calculating the torque can be found in the chapter for the respective ap-
plication model.
Basically the total requirement of the torque results from the following.
• The dynamic torque of the application results from the multiplication of the moment of inertia
and the angular acceleration:
[7-2] Equation 2: Dynamic torque of the application
• The stationary torque M
sds
is calculated on the basis of the application-specific equations that
are listed in the chapter for the respective application model.
• The total torque of the application results from adding the dynamic and the stationary compo-
nent:
[7-3] Equation 3: Total torque of the application
M
sum
M
app
=
M
dyn
J α ⋅ =
M
sum
M
dyn
M
sds
+ =