Introduction
A few days ago, AMG, the high-performance sport brand of Mercedes-Benz, released two powertrain options. On one hand, they are developing the HEV with a relatively small weight increase by using the powertrain from racing cars to create a complete system. On the other hand, they are reusing the system of EQS, which is a pure electric sports car, to develop a pure electric sports car. It seems that the two directions may develop in parallel in the high-end sports field.
Overview of Hybrid System
This AMG E Performance plug-in hybrid system consists of two types of engines, M177 4.0T V8 or M139 2.0T inline 4-cylinder engines (equipped with P0 start-up system on the engine), electric drive system, and battery. The former has a comprehensive output of 600 kW and the latter has an output of 480 kW. The goal is to maximize the characteristics of the engine in terms of comprehensive performance.
This architecture uses a simple P0P4 system and adopts a 2-speed transmission drive shaft on the rear axle, with a comprehensive output of 150 kW.
Interestingly, it is not clear whether only one battery is used here. The P0 drive system and electric turbocharger are both designed based on 48Vi, while the battery used later is 48V. According to the actual design, a multi-voltage output system of 400V to 48V and 12V may have been adopted. Note: This system has increased the weight by 200kg, and Mercedes-Benz may also add a small 48V battery to meet the needs of starting the engine.
Hybrid Battery
What is interesting about this high-power output hybrid battery system is its 6.1 kWh and 89 kg total weight that requires continuous cooling. According to its peak output power of 150 kW, it has an instantaneous discharge demand of around 25 C and a steady-state discharge demand of above 10 C, with a power density of 1.7 kW/kg.
The unique aspect of this battery is its use of 560 high-power cylindrical cells for output. The cells are arranged horizontally and connected to the battery system on both ends. The following figure shows a stack configuration, where a total of eight layers of cylindrical cells form a large integrated module that expands in the opposite direction. Note: This is similar to Toyota’s PHEV solution for China, which also uses cylindrical cells, but the power output of this battery is not as high.
The above figure shows a schematic of the module when it is opened, which is quite clear. The following figure shows the placement of the hybrid battery’s cooling pump on the right and the integration of the heat exchanger in the package. Overall, the structure uses lightweight cast aluminium housing.
Summary:
We can see the development path of hybrids, which is to be as compatible as possible with modular systems and to explore the characteristics of vehicles. Due to the overall weight limit and system layout restrictions, future hybrid systems will have some distinctive batteries that are not quite like the completely homogeneous design of BEVs.
This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.