Calculating The Thyristor Blocking Voltage - Siemens SINAMICS DCM Operating Instructions Manual

Descriptions of functions

10.22 Calculating the thyristor blocking voltage

10.22 Calculating the thyristor blocking voltage
The SINAMICS DCM converter offers the possibility of continually determining the voltage
available at each individual thyristor of the armature converter. The voltage is used to identify
which armature thyristors are presently conducting and which are presently blocked.
This information is available via BICOs (see function diagram 6950).
This information is used for the following functions as input variable:
● Inverter commutation fault detection and initiation of the CCP
● Torque direction changeover (sequential logic module)
The voltage at the armature thyristors is determined from the following measured values:
● 2 phase-to-phase line supply voltages (UV, VW)
● Voltage at a thyristor (for 4Q: Anti-parallel thyristor pair) (X13/X26)
● DC voltage (Va)
Selecting the thyristor blocking voltage calculation using p50166:
The thyristor blocking voltage calculation is only really required in just a few applications and
requires approx. 5% processor utilization; this is the reason that it is deactivated in the
factory setting.
p50166 = 0Thyristor blocking voltage monitoring not active (factory setting)
Activation is recommended in the following cases:
● If a SIMOREG CCP is connected to the SINAMICS DCM.
● If a motor is not connected to the armature converter, but instead, a very large
Note
The thyristor blocking voltage calculation function is available from the following version of
the power interface module
 C98043-A7105-L1-8
 C98043-A7105-L4-8
 C98043-A7106-L1-6
 C98043-A7106-L4-7
 C98043-A7107-... (option L05): All releases
 C98043-A7108-... (option L05): All releases
This information is provided on the bar code label on the printed circuit board.
446
The thyristor that is relinquishing the current must assume the blocking voltage,
otherwise, commutation was unsuccessful.
Before a thyristor of the new torque direction is triggered, all thyristors associated with the
old torque direction must be blocked. The condition is evaluated in addition to the Ia=0
message.
= 1Thyristor blocking voltage monitoring active
inductance.
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
SINAMICS DCM DC Converter