5motor control (mctrl) – Lenze 8400 StateLine User Manual

Page 225

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Lenze · 8400 StateLine · Reference manual · DMS 12.0 EN · 06/2014 · TD05/TD14

225

5

Motor control (MCTRL)

5.10

Encoder/feedback system

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Low speeds (except for edge counting)
For the first method (

C00496

= 1), the minimum speed that can be measured depends on the

encoder resolution.
The quantisation error

• is independent of the encoder resolution,
• exclusively depends on the encoder quality (encoder errors).
• at least amounts to 0.5 rpm.

Internal arithmetic operations automatically maintain the minimally required value of the scanning

time in order to achieve maximum dynamics.

Low speeds with edge counting
The minimum speed that can be measured and the quantisation error of speed measurement in the

edge-counting procedure (

C00496

= 3) depend on the scanning time that can be set in

C00425/1

and the encoder resolution.
Depending on accuracy and the requirements with regard to the dynamic performance, the

respective scanning time must be selected and set in

C00425/1

:

Encoder

resolution

(Number of

increments)

Min. measurable speed in [rpm]

8

16

16

8

32

4

64

2

128

1

256

0.5

Encoder

resolution

(Number of

increments)

Scanning time [ms]

1

2

5

10

20

50

100

200

500

1000

Min. measurable speed in [rpm]

8

1875

938

375

188

93.8

37.5

18.8

9.4

3.8

1.9

16

938

469

188

94

46.9

18.8

9.4

4.7

1.9

0.9

32

469

234

94

46.9

23.4

9.4

4.7

2.3

0.9

0.5

64

234

117

46.9

23.4

11.7

4.7

2.3

1.2

0.5

0.2

128

117

58.6

23.4

11.7

5.9

2.3

1.2

0.6

0.2

0.12

256

58.6

29.3

11.7

5.9

2.9

1.2

0.6

0.3

0.12

0.06

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