Control Techniques SM-Resolver - Page 28

28 SM-Resolver User Guide
www.controltechniques.com Issue Number: 4
A sliding window filter may be applied to the feedback. This is particularly useful in
applications where the feedback is used to give speed feedback for the speed controller
and where the load includes a high inertia, and so the speed controller gains are very
high. Under these conditions, without a filter on the feedback, it is possible for the speed
loop output to change constantly from one current limit to the other and lock the integral
term of the speed controller. The filter is not active if the parameter value is 0 or 1ms,
but operates over the defined window for parameter values of 2, 4, 8 and 16ms.
Pr x.24 = Pr x.05
Encoder simulation output is derived from the resolver input via hardware. The
resolution multiplier can be set up using Pr x.25 as shown in the table below. The
marker output is active when the resolver position is zero, therefore the marker pulse
width is equivalent to one encoder count if the ratio is 1, but is reduced if the ratio is less
than 1.
x.19 Feedback filter
RW Uni US
Ú
0 to 5 (0 to 16 ms)
Ö
0
Update rate: Background read
Value in Pr x.19 Filter window
0 Not active
1 Not active
22ms
34ms
48ms
516ms
x.24 Encoder simulation source
RW Uni PT US
Ú
Pr 0.00 to Pr 21.51
Ö
Pr 0.00
Update rate: Background read
x.25 Encoder simulation ratio numerator
RW Uni US
Ú
0.0000 to 3.0000
Ö
1.0000
Update rate: Background read
Some ratios are not possible when the resolver resolution is reduced below 14 bits as
shown in the table below.
NOTE
Pr x.25
Resolver resolution
14 bit 12 bit 10 bit
0.0000 to 0.0312 1/32 1/8 1/2
0.0313 to 0.0625 1/16 1/8 1/2
0.0626 to 0.1250 1/8 1/8 1/2
0.1251 to 0.2500 1/4 1/4 1/2
0.2501 to 0.5000 1/2 1/2 1/2
0.5001 to 3.0000 1 1 1