Parker GVI Series - MTTF and Mttfd Values for Different Functions; Power Stage

Parker EME
Incorporation of GVI in the vehicle safety system
27 192-300300N1 GVI Frames C, D & E 2019-9
7.18.2.3 MTTF and MTTFd values for different functions
The external interfaces are shown schematically in Figure 15. Table 6 contains calculated MTTFd for
different functions in the motor controller for Category 2 architecture, see ISO 13849-1 chapter 6.2.5.
Functions
MTTFd [years]
MTTF [years]
Input blocks
Digital input
17 081
TBA
Analog input
9 487
Encoder input
5 028
Logic block
Logic MCU1
1 082
Output block
Open Drain output
7 350
Logic block TE (test equipment)
Logic MCU2
1 433
Output block OTE
High side switch
2 249
Supporting blocks
Sensor Supply
3 968
DC/DC
335
CAN
1 684
Motor current measurement
8 456
Motor temperature sensor interface
4 193
Power stage M
54
Power stage L
24
Table 6. MTTF and MTTFd values for different functions
NOTE
MTTFd for complete GVI D is calculated to 36 years and for GVI E 19years
7.18.2.4 Power stage
Although the power stage is an important block in the basic functionality of a motor controller, it has not been
considered in all the MTTFd calculations on the grounds that faults in the power stage will not lead to a
dangerous fault.
It is an inherent trait of AC motor controllers that hardware failures in the power stage do not cause
uncontrolled acceleration in the motor. Instead, the motor is de-energized when the power stage is in failure
mode. When designing a system around an AC motor controller though, it is important to ensure that is
doesn’t result in a dangerous situation in the application when the motor loses power. As an example, a
system shall not depend 100 % on the motor controller to provide emergency braking power in a vehicle that
must be brought to a stop to ensure the safety of it. In such a case, some redundant braking mechanism
must also be installed.