25 kilograms of Pure Energy | Automotive content from Electronic…

22 мая 2015 | Author: | No comments yet »

Mercedes-Benz C 200 K W20

25 kilograms of Pure Energy

25 That’s the weight of the hybrid in the 2010 Mercedes-Benz S-Class S 400 The battery consists of 35 cylindrical, lithium-ion batteries and delivers a power of up to 15 kW (20 HP). The electric and protection of this little of energy is one of the battery ECU’s important tasks. The ECU’s were developed in a joint between Johnson Controls and dSPACE TargetLink is used to the ECU software.

Mercedes-Benz S 400 HYBRID

The S 400 is a mild hybrid in which the drive is used for engine the start-stop function, boosting and recovery. To save space, the disk-shaped electric drive is in the enclosure of the torque converter, the engine and the 7G-TRONIC seven-speed transmission. This external motor is a 3-phase rotary permanent magnet electric with a maximum power of 15 kW (20 HP) and a torque of 160 Nm at an operating voltage of 120 V.

So space is saved by installing the battery in the engine compartment in of the conventional starter battery the vehicle’s spacious interior and do not need to be altered (Figure 1). The battery is not only an energy for the electric motor. Via the voltage the battery is also connected to the electrical system that the headlights and consumer comfort As with traditional autos, start-up is the biggest demand on the battery. If the battery charge is low due to low outside temperatures, and so forth, it manifests itself during start-up. If the charge ever too low, the hybrid system jump-starting.

A 12-volt lead-acid battery is in the trunk. It supplies power to consumer features and also to the system for the high-voltage components. to support from the lithium-ion it can be considerably smaller and lighter.

The hybrid has a specially designed engine. It utilizes the advantages of the principle, which increases the thermal efficiency and at the same reduces fuel consumption and emissions. The disadvantages of the Atkinson such as a relatively low torque in the speed range, are compensated by the motor.

Comprehensive energy ensures that all the components in the powertrain (battery, electric voltage converter) respond to the vehicle’s requirements. The electric supports the combustion engine acceleration and acts as a generator an energy recovery function braking. Especially during the phase, the hybrid battery electric power for the vehicle system via the voltage converter. suitable shifts in the working ensure that the combustion always runs in its optimum range, even in such situations as cross-country drives and traffic.

Cooled Hybrid

The heart of the modular, very very efficient hybrid is the new high-voltage lithium-ion battery 2), which was specially developed for use in Its essential advantages over nickel metal hydride are greater energy density and electric efficiency, plus compact dimensions and lower The hybrid battery supplies a voltage of 128 V at a maximum current of 200 A in the and discharge directions. It consists of 35 cells with a nominal of 3.6 V each and a capacity of 7 Ah (Figure 3). For the battery is connected to the vehicle’s control. Battery cooling has priority over the driver’s settings and can demand full power even if the climate is switched off.

The battery management system is the control center for the electric, (physical) and chemical processes in the The BMS is an independent ECU installed in the battery and has the functions:

Safety functions voltage cut-out)

Charge (via the instrument cluster, see 4)

Computation of current, voltage, and limits

Temperature management

of battery aging

Balancing charge differences)

Besides these control functions, the ECU acts as a black box, is, it stores all the battery data so that it can be retrieved via diagnostic To guarantee safe operation at the voltages and currents, there are safety functions that that the battery’s high-voltage are not live unless the battery is in The battery is therefore completely to install, transport and store.

Networking the Battery Management

To do its work properly, the BMS has to intervene in systems and also fetch for evaluation from other It is therefore connected to all the ECUs in the branch:

Energy management ECU)

Power electronics motor)

Voltage converter

To ensure a fast response to the battery and the climate control some messages directly, for the battery’s cooling requests and the status.

Control Strategy for the

To give the battery cells a life and make optimum use of power, the cooling strategies are to hold the battery temperature at 30°C. Under extreme overheating is avoided by means of and voltage limits. These prevent long-term damage and of capacity in the cells. The temperature is designed such that the temperature of 50°C is exceeded in exceptional circumstances (Figure 5).

temperatures, which are particularly to occur when the vehicle is not in can also damage the battery. operation, the battery is immediately by current flow. If the current is too high at temperatures below lithium precipitation can occur, drastically lowers the battery

The vehicle’s idle phases are used for recalibration, safety and balancing, that is, equalizing charge differences. Balancing is important because the battery’s decisively depends on an even state in the cells. To balance the levels of all the cells, specific are recharged on the basis of load analyses. This means the battery’s capacity can always be utilized without overloading cells (Figure 6).

Model-Based Development Process

Mercedes-Benz C 200 K W20

One of project’s greatest challenges was to the know-how of battery experts and the of automotive engineers, and develop a that guarantees high availability, while protecting the cells at the same time. The was to take theoretical battery and cell data obtained laboratory conditions, and shape into executable software in a way that they would be in practice, yet still provide precision.

Model-based development and the code generator TargetLink dSPACE made it possible to integrate existing Simulink algorithms and battery characteristics the controller model, and to use existing battery models for validation. the aim of this project was to design the control for lithium-ion technology, the software had to be developed entirely scratch, without using code from previous In-house modeling guidelines on the modeling guidelines published by helped to prepare the model for the possible implementation as efficient code.

The function developers for the management system (EMM) in the engine ECU also used so working with them ran and coordination between EMM developers and BMS in different companies was much

Implementing the Battery Controller

The ECU has a TriCore microcontroller from To implement the modeled controller on the ECU, production-capable fixed-point had to be generated from the model. all data that had global in the project, such as calibratable was defined in the dSPACE Data The necessary scaling of variables was in the model with the aid of the scaling provided by TargetLink. The fixed-point was validated by comparing model-in-the-loop and software-in-the-loop (SIL) simulations. The behavior and the resource consumption of the for the target processor were by processor-in-the-loop (PIL) simulation the TriBoard TC1796 evaluation (Figure 7).

Even the very first PIL revealed that the code had good run-time behavior particularly computation-intensive program The processor with its 150 MHz clock continued to fulfill the software’s requirements as development continued. generated approximately 25,000 of code for the controller model. The code generator was no problem to and quickly led to production-level results.

and Outlook

The battery ECU was first on a test bench. Verifying the functions and the effectiveness of the temperature were a particular focus Then the system’s suitability for roads, and for summer and winter was investigated in test drives. The battery plus ECU proved to be a system that is able to provide sufficient electric

Investigations into using the in other vehicles are currently The modular design of the software it possible to take the battery that were developed and in this project and reuse in other projects.

Torben Materna is a project for software development and developer of battery management systems at Controls-SAFT Advanced Power in Hanover, Germany

“With the code generator TargetLink, we turned a newly developed model into production-level for a hybrid battery management

Torben Materna, Johnson

Atkinson principle – Prolonging the phase compared with the phase in a four-stroke engine by the inlet valve open between intake and compression stroke”). Result: Greater and lower consumption.

Boosting – in the electric motor when peaks occur

Mild – A hybrid vehicle whose motor supports the combustion when required, but does not propulsion on its own.

Recovery – excess energy in the battery example, during braking).

Mercedes-Benz C 200 K W20
Mercedes-Benz C 200 K W20
Mercedes-Benz C 200 K W20


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