Engine On Energy Management, Function - GF54.10-P-1060KJ
MODEL 453.0 (except 453.091), 453.3 (except 453.391), 453.4 (except 453.491)
Function requirements, general
- Signal "engine running" set
The ME-SFI [ME] control unit (N3/10) sends the "Engine running" signal over the interior CAN (CAN B) to the driver-side SAM control unit (N10/11).
Engine on energy management, general
Engine on energy management ensures the stability of the on-board electrical system as well as an even charge balance in the on-board electrical system battery (G1).
If lots of electrical consumers are operated simultaneously, overload situations may occur, which have to then be buffered by the on-board electrical system battery. If such an overload situation lasts for an extended period or if the charging capacity of the on-board electrical system battery is low, a negative charge/discharge ratio could arise. In such an instance, the mobility and the stable supply of all electrical consumers can no longer be assured. In situations where the on-board electrical system is overloaded for prolonged periods, the engine ON energy management increases the power output of the alternator (G2). Energy management for driving encompasses the following subfunctions:
- Function sequence for voltage provision
- Function sequence for ideal speed control
Function sequence for voltage provision
The voltage provision function comprises the following subfunctions:
- Function sequence for determining battery charge level
- Function sequence for charging on-board electrical system battery
- Function sequence for alternator regulation (alternator management)
Function sequence for determining battery charge level
The state of the on-board electrical system battery is recorded by the battery sensor (B95).
The Energy Smart Management integrated into the driver-side SAM control unit (N10/11) uses the voltage, current and temperature measurements of the battery sensor to determine the charge level, as well as the efficiency of the on-board electrical system battery. The charge level of the on-board electrical system battery is the ratio of the current charge to the maximum storable charge, given as a percentage. This is based on the calculation of the internal resistance. This, along with the battery capacity, is then used to compute the charge stored in the on-board electrical system battery. The driver-side SAM control unit reads in the battery sensor data over the battery sensor-LIN (LIN B15) and uses the current terminal voltage and the current no-load voltage to calculate the specified voltage for the alternator required to supply the energy.
Function sequence for charging on-board electrical system battery
Charging of the on-board electrical system battery requires that the specified voltage be determined. The specified voltage is the voltage that must be present at the terminals of the on-board electrical system battery in order to charge the on-board electrical system battery in an optimum manner.
Depending on various factors, the specified voltage is then determined based on the "Energy Smart Management" or the temperature-specific charging characteristic incl. rapid-charging function. After the engine is started, quick charging is performed first at high voltage until the charge level of the on-board electrical system battery is recognized as being sufficient.
Rapid charging is conducted depending on the measured no-load voltage for the battery, with up to 15.6V and it is then stopped after t = 30 minutes. After this, the Energy Smart Management system is then ignored.
Quick charging:
- Voltage up to U_=_15.6_V
- Once after terminal 50 ON
- Optimized battery charge level even in short-distance operation
- End of rapid charging after t = 30 min
- Coolant temperature TCool > 15°C
Transition to "Energy Smart Management"
- Quick charging ended
- Stable engine operation
- Temperature of on-board electrical system battery 0°C < TBatt < 50°C
- Charge level of on-board electrical system battery U > 12 V
Energy Smart Management
- On-board electrical system voltage dependent on battery temperature and charge level between U = 12 V and U = 14.8 V
- Consumer power supply primarily through on-board electrical system battery
- Linear charging characteristic
Transition to charging in decel mode
- Stable engine operation
- ME-SFI [ME] control unit detects deceleration mode
Charging in deceleration mode
- Voltage up to U = 15 V
- Activated by driver-side SAM control unit
- Charging of on-board electrical system battery and supply to consumers, when energy is available "free of charge" (regenerative braking)
Function sequence for alternator regulation (alternator management)
Alternator regulation (alternator management):
- Takes place in driver-side SAM control unit
- Sets the specified voltage of the energy management
- Switches to regenerative braking voltage in deceleration mode
- In exceptional circumstances this provides a lower voltage (e.g. stall protection, cold start at high altitude, catalytic converter heater)
The alternator control actuates the alternator's power output. The driver-side SAM control unit communicates over the drive-LIN (LIN C1) with the alternator and assesses the alternator operating rate.
The state of the on-board electrical system battery is recorded by the battery sensor. The battery sensor sends corresponding parameters for the on-board electrical system battery over the battery sensor-LIN to the driver-side SAM control unit. The driver-side SAM control unit evaluates all relevant information and uses it to calculate the required alternator specified voltage. Taking additional variables (e.g. A/C ON) into account, the driver-side SAM control unit uses the required alternator specified voltage to calculate the optimum specified voltage for the alternator. The driver-side SAM control unit then request the calculated, optimum specified voltage over the drive-LIN on the alternator, which then sets it. The driver-side SAM control unit compares the optimum specified voltage for the alternator with the actual alternator capacity, thereby enabling it to determine the energy level of the on-board electrical system. The continuous comparison of these two values and the corresponding corrections, is designated as energy management. As soon as it becomes apparent that the on-board electrical system voltage is not high enough, the power management is gradually reduced. The alternator can then make its full output available.
Function sequence for ideal speed control
The ideal speed control increases the idle speed, when the battery voltage drops below a voltage level of V = 12.5 V. The on-board electrical system battery is discharged when the level drops below this voltage limit. The idle speed control function should help to prevent this discharging process. The ME-SFI [ME] control unit is responsible for regulating the idle speed control increase.
| Overview of energy management system components | GF54.10-P-9990KJ |