Part 2
2 Monitoring Functions Contd...2.6 Phase U/W over current monitor (P0C01)
The goal is to detect an over current in phase U or W
2.6.1 Monitoring strategy
This is diagnosis is implemented in the inverter hardware which detects an over current
2.6.2 Enable condition
No enable condition necessary.
2.6.3 Chart(s) and flow chart(s)
2.7 Drive motor position sensor system monitor
The drive position sensor is used to detect the actual angle of the rotor field and to calculate the drive motor speed. The sensor consists of three different hall sensors which are called sensor 1...3.
The output of each hall sensor is converted inside the DMCM to a digital "high" or "low" signal. Under good conditions the sensor combination "high-high-high" or "0-0-0" is not possible.
The diagnosis of the sensor system is staged in a error detection of the sensor system and a detailed pin pointing to each sensor 1...3.
2.7.1 Drive motor position sensor system short cut to battery (P0A42)
Stage 1 diagnosis
The goal of this diagnosis is to detect a short cut to ground of any of the three position sensors. In this stage there is no pin pointing implemented, but it will be done in stage 2 after the detection of this error.
2.7.1.1 Monitoring strategy
The physical position of the three sensor is prohibits the sensor combination "1-1-1" and "0-0-0". If this combination occurs an drive motor position sensor system "short cut to battery" is detected.
2.7.1.2 Enable condition
- drive motor phase angle is valid
2.7.1.3 Chart(s) and flow chart(s)
2.7.2 Drive motor position sensor system "short cut to ground" or "open loop" (P0A41)
Stage 1 diagnosis
The goal of this diagnosis is to detect a short cut to ground or open loop of any of the three position sensors. In this stage there is no pin pointing implemented, but it will be done in stage 2 after the detection of this error.
2.7.2.1 Monitoring strategy
The physical position of the three sensor is prohibits the sensor combination "1-1-1" and "0-0-0". If the combination "0-0-0" occurs, a drive motor position sensor system "short cut to ground" or "open loop".
As the sensor system has a common power supply line a short cut or open loop of the whole sensor system is possible.
2.7.2.2 Enable condition
- drive motor phase angle is valid
2.7.2.3 Chart(s) and flow chart(s)
2.7.3 Drive motor position sensor system "rationality fault" (P0A40)
The goal of this diagnosis is to detect implausible position sensor signals. If this error occurs either the sensor system or the DMCM has to be replaced.
2.7.3.1 Monitoring strategy
The time between two transitions of the position sensor depends on the actual drive motor speed. If a transition time is lower than a lower limit a drive motor position sensor system "rationality fault" is detected.
2.7.3.2 Enable condition
- drive motor speed is within the operation range
2.7.3.3 Chart(s) and flow chart(s)
2.7.4 Drive motor position sensor 1...3 "short cut to battery" (P0C53, P0C5D, P0CDD)
Stage 2 diagnoses for pin pointing
The goal of this diagnosis is to detect which of the three sensor 1...3 has a "short cut to battery"
2.7.4.1 Monitoring strategy
After the detection of the stage 1 diagnosis drive motor position sensor system "short cut to battery" the pin pointing will be activated. This is done within the next key on cycle after detection of the system error. Therefore an offset angle calibration is commanded by the DMCM. This means the electric drive motor will be accelerated without traction to the wheels.
Depending on which of the three sensors is erroneous 2 of the 6 valid combination will not be occur, for example "0-0-1" will not occur if sensor 1 has a short cut to battery.
2.7.4.2 Enable condition
- stage 1 failure "short cut to battery" detected
2.7.4.3 Chart(s) and flow chart(s)
2.7.5 Drive motor position sensor 1...3 "short cut to ground" or "open loop" (P0C52, P0C5C, P0CDC)
Stage 2 diagnoses for pin pointing
The goal of this diagnosis is to detect which of the three sensors 1...3 has a "short cut to ground" or "open loop"
2.7.5.1 Monitoring strategy
After the detection of the stage 1 diagnosis drive motor position sensor system "short cut to ground" or "open loop" the pin pointing will be activated. This is done within the next key on cycle after detection the system error. Therefore an offset angle calibration is commanded by the DMCM. This means the electric drive motor will be accelerated to about 1000 rpm without traction to the wheels.
Depending on which of the three sensors is erroneous 2 of the 6 valid combination will not be occur, for example "1-0-1" will not occur if sensor 1 has a short cut to ground.
2.7.5.2 Enable condition
- stage 1 failure "short cut to battery" detected
2.7.5.3 Chart(s) and flow chart(s)
2.8 Drive motor offset angle calibration monitor
2.8.1 Offset angle calibration cycle
The offset angle calibration is used, if either
- no offset angle is stored,
- fault code memory was cleared,
- fault suspicion (performance check/ position sensor) is present.
The offset angle calibration cycle is divided into three phases.
First phase: A basic rotating field is used to rotate the drive motor with low rpm. Under this condition, a first offset angle can be estimated.
Second phase: The estimated offset angle is used to speed up the drive motor to a maximum rpm.
Third phase: While freewheeling down to zero rpm, the accurate offset angle will be calculated.
2.8.2 Incorrect phase connection or sensor position (P0C4E)
2.8.2.1 Monitoring strategy
By using the synthetic rotation field in phase 1 (figure 11) the rotation direction of the drive motor will be monitored. To recognize a wrong direction the DMCM checks the order of position sensor signal information.
If the order is wrong, the calibration cycle will be stopped and a fault code will be stored.
2.8.2.2 Enable condition
The system has to be in the state "offset angle calibration".
2.8.2.3 Chart(s) and flow chart(s)
2.8.3 Offset angle estimation (P0C17)
2.8.3.1 Monitoring strategy
After the offset angle estimation within phase 1, this angle is used to accelerate the drive motor. If the drive motor starts to move in wrong direction, the calibration cycle will be stopped and a fault code will be stored.
2.8.3.2 Enable condition
The system has to be in offset angle calibration mode. No further conditions necessary
2.8.3.3 Chart(s) and flow chart(s)
2.8.4 Timeout while acceleration (P0C4E)
2.8.4.1 Monitoring strategy
After the offset angle estimation within phase 1, this angle is used to accelerate the drive motor to given maximum rpm. If it takes to long to reach this given drive motor speed, the calibration cycle will be stopped and a fault code will be stored.
2.8.4.2 Enable condition
The system has to be in offset angle calibration mode.
No further conditions necessary
2.8.4.3 Chart(s) and flow chart(s)
2.8.5 Drive motor speed to high (P0C4E)
2.8.5.1 Monitoring strategy
This monitor will check if the drive motor speed will over travel the desired maximum speed within phase 2 (figure 11). If the drive motor speed is too high, the calibration cycle will be stopped and a fault code will be stored.
2.8.5.2 Enable condition
The system has to be in offset angle calibration mode.
No further conditions necessary
2.8.5.3 Chart(s) and flow chart(s)
2.8.6 Unplausibility of offset angle calibration while freewheeling (P0C4E)
2.8.6.1 Monitoring strategy
Within phase 3 (figure 11), the DMCM will check if there is any current flow from the free-wheeling diode to the DC voltage link. If a current flow is detected, the rotor could be decelerated and a proper offset angle calculation is not possible. If that case the calibration cycle will be stopped and a fault code will be stored.
2.8.6.2 Enable condition
The system has to be in offset angle calibration mode with freewheeling. No further conditions necessary
2.8.6.3 Chart(s) and flow chart(s)
2.8.7 Timeout while offset angle calculation (P0C4E)
2.8.7.1 Monitoring strategy
The calculation of the offset angle while freewheeling (figure 11: phase 3) has to be done in a maximum time period.
If the time to calculate the offset angle is to long, the calibration cycle will be stopped and a fault code will be stored.
2.8.7.2 Enable condition
The system has to be in offset angle calibration mode.
No further conditions necessary
2.8.7.3 Chart(s) and flow chart(s)
2.8.8 Offset angle deviation (P0C17)
2.8.8.1 Monitoring strategy
After calculation of the offset angle while freewheeling, the difference between this angle and the estimated angle from phase 1 will be checked. If the deviation between estimation and calculation exceeds a limit, the calibration cycle will be stopped and a fault code will be stored.
2.8.8.2 Enable condition
The system has to be in offset angle calibration mode.
No further conditions necessary
2.8.8.3 Chart(s) and flow chart(s)
2.9 DC link voltage sensor monitor
2.9.1 DC link voltage sensor "out of range high" (P0C79)
2.9.1.1 Monitoring strategy
The Monitoring function checks the DC link voltage sensor to exceed a maximum limit of voltage.
2.9.1.2 Enable condition
No enable condition necessary.
2.9.1.3 Chart(s) and flow chart(s)
2.9.2 DC link voltage sensor rationality (P0D2E)
2.9.2.1 Monitoring strategy
This monitoring strategy combines the DC link voltage and the high voltage battery voltage signal via CAN. If the deviation between both signals is too high, a DC link voltage sensor malfunction is detected. The high voltage battery voltage signal was monitored by the battery energy control system while its initialization phase. If the BECM has detected a voltage sensor malfunction the drive motor control module will not get into drive state and did not receive any this CAN message.
2.9.2.2 Enable condition
BECM message can be received
System state: drive
2.9.2.3 Chart(s) and flow chart(s)
