Synchronizing controller
6
MG.10.N4.02 - VLT is a registered Danfoss trademark
Calculation with insufficient numerical values
The master/slave gear ratio (numerator to denominator) is now calculated as follows:
Master side = increments * i1 * i2 * power take off =
460995
,
48
*
102
1
*
40
20
*
33
.
30
*
1024
=
π
mm
incr
Slave side = increments * i1 * power take off
=
7856
,
29
200
*
8
1
*
54
.
46
*
1024
=
mm
incr
This gives a ratio of
7856
,
29
460995
,
48
That gives a numerical value of 48,460995 for the numerator and 29,7856 for the denominator. Note: It
is only possible to enter integer values. The most serious error: The master expression contains the
value Pi, an infinite number sequence. Even with small numerical values for master and slave, the
effect would always be that the drives drifted apart, as the Numerator: Denominator expression can
never be an integer.
Another error arises from the gear ratios given, as the master drive was specified with a value of i =
30.33. The correct ratio is easily found by recalculating the individual numbers of teeth. The gear is a
2-stage gear; the first stage is formed from two pinions, 126 to 27, and the second stage from two
pinions, 117 to 18.
The ratio is calculated as:
1/3
30
18
*
27
117
*
126
=
The specified value of 30.33 thus deviates by 0.1
0
/
00
.
This may appear small; if this error is related to the encoder resolution, however, it will be seen that
even this error is serious.
From the example it can be seen that it is important to maintain the exact values of the gear stages
and to ensure that the data include Pi either for both drives or for none of them.
Example with corrected numerical values:
Master side: Gear 1st stage 126/27 2nd stage 117/18; belt ratio 40/20; drive shaft 100 mm
Slave side: Gear 1st stage 97/10, 2nd stage 43/11, 3rd stage 27/22; effective diameter of the
sprocket wheel 510mm
Master side:
π
*
102
*
40
*
18
*
27
20
*
117
*
126
*
.
1024Incr
Slave side:
π
*
510
*
22
*
11
*
10
27
*
43
*
97
*
.
1024Incr
To remove Pi from the equations, substitute both equations into the combined formula:
Slaveside
Masterside
=
÷
π
*
102
*
40
*
18
*
27
20
*
117
*
126
*
.
1024Incr
π
*
510
*
*
22
*
11
*
10
27
*
43
*
97
*
.
1024Incr
π
π
*
102
*
27
*
43
*
97
*
.
1024
*
40
*
18
*
27
22
*
11
*
10
*
*
510
*
20
*
117
*
126
*
.
1024
Incr
Incr
Reduce by Pi and 1024 incr.:
102
*
27
*
43
*
97
*
40
*
18
*
27
22
*
11
*
10
*
510
*
20
*
117
*
126
Reduce further:
27
*
43
*
97
*
27
117
*
22
*
11
*
5
*
5
*
7