Lenze i55AE155F

Details on encoder signal loss monitoring
The encoder signal loss monitoring disnguishes between the following signal failures:
a)
Complete failure (no encoder signals available at all, e. g. in case the encoder current sup-
ply has failed)
b)
Only one track has failed (track A or track B)
In order to detect a complete failure, the inverter calculates internally two trigger thresholds
for monitoring based on the conguraon of the HTL encoder:
1.
Based on the encoder resoluon set in 0x2C42:001 (P341.01), the minimum output fre-
quency is calculated:
max
number of motor pole pairs number of motor pole pairs
Minimum output frequency [Hz]
t [s] encoder increments
encoder increments
0.001 [s] 4
revolution
edge revolution
= =
× ×
×
Note: The maximum me (t
max
) per edge is 0.001 s. In order to prevent a false tripping,
this value is mulplied by the factor 4.
Calculaon example:
•
Number of pole pairs = 2
•
Encoder resoluon = 128 increments/revoluon
2
minimum output frequency [Hz] 3.9 [Hz]
0.001 [s] 4 128
= =
× ×
2.
The maximum permied me is calculated in which a new signal edge of the encoder
must arrive:
1
time per edge [s]
encoder increments
encoder frequency [Hz]
revolution
=
×
If the calculaon with the (synchronous) encoder frequency at minimum output frequency
(here: 2 * 3.9 Hz) is carried out, the resulng me interval equals the maximum me per
edge (here: 0.001 s)
If the real encoder frequency is lower than the calculated minimum output frequency AND if
the new signal edge has not arrived within the maximum permied item, monitoring is trig-
gered. The complete failure is displayed via the status bit 4 in 0x2C42:007.
If only track A or B fails, signals are connued to be detected. In this case, however, the sign of
the frequency changes with every new signal edge. In order to detect the failure of only one
track, an internal counter is increased by 1 every me the sign between two signal edges
changes. If the sign is unchanged in two signal edges in a row, the counter is reset. If the coun-
ter reaches the counter content "100", monitoring is triggered. The failure of only one track is
displayed via the status bit 5 in 0x2C42:007.
Both in case of a complete failure and in case only one track fails, the error message "Encoder
open circuit" (error code 29445 | 0x7305). The error response can be selected in 0x2C45
(P342.00).
Addional funcons
Encoder sengs
Encoder monitoring
499