(Energy Management Detailed Information - GF54.10-S-0023A)
Model 447
With Code M7E (Electric motor 150 kW/battery 60 kWh (usable))
With Code M8E (Electric motor 85 kW/battery 60 kWh (usable))
With Code ME4 (Electric motor 145 kW)
With Code XM7 (MOPF II)
Overview of energy management, shown on model 447.8
Topology of energy management, shown on model 447.8
Overview
This document contains information on:
- General
- Energy management for high-voltage on-board electrical system
- Energy distribution
- Recuperation
- On-board electrical system support
- Drive programs
- Function
- Switching on and disconnecting the high-voltage on-board electrical system
- Deactivation of the high-voltage on-board electrical system in the event of an accident and short circuit
- Manual power disconnect of the high-voltage on-board electrical system
- High-voltage disconnect device (S7) (Service separating point in engine compartment)
- Disable (free of voltage)
- Alternative high-voltage disconnect device in case of emergency (high-voltage rescue separation point)
- Switching on and disconnecting the high-voltage on-board electrical system
- Energy management for high-voltage on-board electrical system
General
Energy management for high-voltage on-board electrical system
The high-voltage on-board electrical system makes it possible to operate the electric machine for the electric drive The high-voltage on-board electrical system also supplies consumes with high energy demands e g the electric refrigerant compressor (A9/6) the control unit for the high-voltage PTC heater (N33/7), and the control unit for the battery heater (N33/8), with electrical energy.
The high-voltage on-board electrical system energy management manages the provision (supply) and consumption (balance) of electrical energy. The goal is a low energy consumption and an optimal charging process.
In certain driving situations, the electric machine is used in generator mode for generating electrical energy (recuperation). The high-voltage on-board electrical system supplies the 12 V on-board electrical system with electrical energy from the high-voltage battery via the DC/DC converter control unit (N83/3).
The energy management function is integrated into the drivetrain control unit (N127). Some of its basic tasks are listed below:
- Activation and/or deactivation of high-voltage components in accordance with the high-voltage safety requirements
- Determining the usable amount of energy in the high-voltage battery
- Energy distribution between the high-voltage components based on the available energy
- Forecast of currently available electrical power of drivetrain
- Coordination of the charging process (interaction between the high-voltage battery and charge components)
- Calculation of the electric range and the electrical consumptions for the trip computer
- Check of high-voltage safety requirements and as-required transfer to a safe state
The following component parts are extensively involved in high-voltage on-board electrical system energy management:
- Electric machine (A79/1)
- Power electronics control unit (A79/3)
- DC charging/AC charging vehicle socket (G10)
- High-voltage battery (G1/29)
- DC charge-connection unit (N24/6)
- DC/DC converter control unit (N83/3)
- AC charger for high-voltage battery (N83/11)
- Drivetrain control unit (N127)
Energy distribution
The operation strategy in the vehicle is designed to control the flow of energy dynamically. Consequently, the necessary energy is prepared in good time for the given driving condition that arises. For this, numerous pieces of information are sent to the intelligent control system, which evaluates this information and allows the respective drive torques to be provided. This information includes the driver request, the requests for the vehicle and the environmental conditions.
Also, the achievable service life of the energy storage unit very much depends on the operation strategy. To increase the range of the vehicle, this requires (particularly with regard to heating) an intelligent energy management system that uses all available energy sources. In this respect, the energy distribution to the high-voltage components is limited depending on the current driving situation (12 V on-board electrical system, heating and climate control functions).
Recuperation
The drive concept permits recuperation during vehicle deceleration. The electric machine is operated as an alternator and generates a braking torque on the wheels. The electric power generated flows back into the high-voltage battery.
The energy management system controls the return flow of the energy.
On-board electrical system support
All implemented control units are supplied via the on-board electrical system battery (G1) of the 12 V on-board electrical system.
When the vehicle is stationary and the ignition is not switched on, all consumers are supplied by the on-board electrical system battery.
On-board electrical system support ensures that the on-board electrical system battery is charged at all times. The on-board electrical system is continuously supported via the DC/DC converter control unit (N83/3). The state of charge varies between 12 V and approx. 14.8 V depending on the state of charge of the on-board electrical system battery (G1) and other environmental conditions.
The DC/DC converter control unit (N83/3) converts the high voltage from the high-voltage on-board electrical system to the voltage level of the 12 V on-board electrical system for supplying 12 V consumers and for charging the on-board electrical system battery (G1). To do this, the DC/DC converter control unit (N83/3) receives a voltage specification for the 12 V on-board electrical system from the signal acquisition and actuation module (SAM) control unit (N10/1).
After the ignition has been switched on the available voltage of the on-board electrical system battery is checked and as required supercharged and supported via the DC/DC converter control unit (N83/3) by the high-voltage battery (G1/29) The consumers of the 12 V on-board electrical system continue to be supplied by the on-board electrical system battery The high-voltage onboard electrical system is continuously switched in while driving
When the charging cable is connected to the DC charging/AC charging vehicle socket (G10) and to a private power network (stationary domestic outlet) or a public power network (charging station) the high-voltage battery (G1/29) is externally charged In addition a "Mercedes-Benz Wallbox Home" is available Mercedes-Benz battery-electric vehicles can be charged much quicker via this than via a conventional mains socket.
Drive programs
The drive programs have different features in the mileage in the response time of the accelerator pedal and in the heating and climate control output When considered together, these properties can result in different vehicle ranges
Function
Switching on and disconnecting the high-voltage on-board electrical system
Always perform a power disable of the high-voltage on-board electrical system using XENTRY Diagnosis.
The repair maintenance and diagnostic activities in vehicles with a high-voltage onboard electrical system must only be performed by qualified employees Documented attendance of a high voltage training session is the minimum required qualification for this Disabling (de-energization) of the high-voltage on-board electrical system prior to undertaking activities on the vehicle and for the subsequent commissioning following the activities must only be performed by an electrician trained in dealing with high-voltage on-board electrical systems in motor vehicles in the series production vehicle field of activity.
The high-voltage on-board electrical system can and must be either switched on or disconnected as necessary according to the operating situation, e.g. charging, service, or accident.
Deactivation of the high-voltage on-board electrical system in the event of an accident and short circuit
Deactivation of the high-voltage on-board electrical system in the event of an accident is initiated by triggering the pyrofuse. The separator is actuated by the Supplemental Restraint System control unit (SRS) (N2/5) if a crash is detected.
This results in all the poles being separated from the power sources, deactivation of the electric machine's generator mode, and discharging of the capacitors to a value less than the dangerous voltage range. A gradual deactivation of the high-voltage on-board electrical system takes place in the event of a short circuit using software and electrical fuses.
In the event of an accident, a security system recognizes the severity of the crash and decides whether the high-voltage on-board electrical system must be switched off reversibly or irreversibly.
- Reversible: A small amount of minor damage without airbag deployment or impairment of the high-voltage on-board electrical system. The high voltage buffer is discharged within a few seconds. The vehicle can be restarted via the ignition.
- Irreversible: The power supply of the contactors is interrupted by a pyrotechnical element. The high voltage buffer is discharged within a few seconds. The vehicle cannot be started again by the operator.
Manual power disconnect of the high-voltage on-board electrical system
Before carrying out work on the high-voltage on-board electrical system, an absence of voltage and the de-energized state of the high-voltage on-board electrical system must be ensured.
The three safety rules must be observed and adhered to when conducting such work:
- Disable (free of voltage)
- Secure against reactivation.
- Check and ensure absence of voltage (attach vehicle power disable event log to the vehicle so that it is clearly visible).
For the power disconnect of the high-voltage on-board electrical system with XENTRY Diagnosis, the safety note must be observed and the instructions must be followed.
In this process, for example, the actual values are read out and evaluated from the respective control unit and the high-voltage component lock in the control units is actuated prior to activation of the high-voltage disconnect device (S7).
In the event of an accident, voltage must also be removed from the vehicle by the rescue services.
Two high-voltage disconnect devices are available for the manual power disconnect:
- High-voltage disconnect device (S7) (Service separating point in engine compartment)
Power disconnect of the high-voltage on-board electrical system, e.g. for work in the workshop, but also in the event of an accident.
- Alternative high-voltage disconnect device in case of emergency (high-voltage rescue separation point)
Irreversible power disconnect of the high-voltage on-board electrical system only in case of emergency, e.g. in the event of an accident.
High-voltage disconnect device (S7) (Service separating point in engine compartment)
The high-voltage disconnect device (S7) serves to secure the power disconnect and is located on the right front module holder in the engine compartment.
The high-voltage disconnect device (S7) disconnects the power supply of the contactors so that these can no longer be activated.
Actuate high-voltage disconnect device (S7)
Disable (free of voltage)
The bridging plug (2) is, as shown in the picture sequence (A, B, C), unlocked at the fuse (4), pulled out of the high-voltage disconnect device housing (1) and secured with a padlock (3) against a restart procedure.
Alternative high-voltage disconnect device in case of emergency (high-voltage rescue separation point)
The alternative high-voltage disconnect device (high-voltage rescue separation point) must only be actuated if the high-voltage disconnect device (S7) in the engine compartment cannot be actuated as this step is irreversible.
For the rescue services there are two special adhesive labels with the QR Code® as a link to the rescue card These are located on the driver's side B-pillar as well as on the front passenger side B-pillar and identify the location of the high-voltage on-board electrical system components as well as pyrotechnical devices and disconnect devices.
The alternative high-voltage disconnect device is located behind the front passenger seat box cover (5). It is identified with an information label (6) on the electric line. When doing so, cut through the electric line at the marked connecting point. The line is not located on the high-voltage on-board electrical system.
The standardized high-voltage rescue separation point is provided to allow emergency services to irreversibly shut off the high-voltage on-board electrical system if rescue and recovery is required.
| Detailed information | |||
| Overall network (GVN), detailed information | GF00.19-S-0020-01C |