[Taycan In-depth Analysis Series 2] Design details corresponding to the 800V battery

1) From modules 1 to 13, the upper and lower 4 modules form a small loop to form 3 groups

2) There is not much regularity in the arrangement of 14-26 

3) 28-33 are serially arranged. Note that the fuse of the main system is placed in the second-layer module and has a separate fuse box. 

Figure 2 Connection of modules in the battery system 

The high-voltage distribution box in the Taycan contains:

High-voltage current and voltage measurement sensors, fuses for front and rear inverter drives (350A+350A), main system fuses on the second-layer module, Hall current sensors, contactors for high-voltage positive and negative poles, pre-charge contactors with 30 ohm pre-charge resistors 

The high-voltage system adopts the strategy of pre-charging on the negative electrode. When the high-voltage system is enabled, the following high-voltage contactor sequence is used: high-voltage positive front end, high-voltage positive rear end, high-voltage negative pre-charge, and finally high-voltage negative electrode. When the system is powered off, the sequence is the opposite of the above. In emergency situations such as collisions, the contactors will adopt a simultaneous disconnection control strategy. 

Figure 3 Design of high voltage distribution box 

Porsche also defines the system functions of the battery management system. The battery management system realizes the functional safety, monitoring and temperature control of the high-voltage battery (starting the coolant pump of the high-voltage battery). The main functions include: 

Fault storage and fault memory output, monitoring of the SOC of the high-voltage battery and single battery, capacity calculation of single battery/battery, battery SOH aging calculation, monitoring of insulation resistance, current level monitoring, disconnection of the high-voltage system in the event of a fault, balancing control, output and input of data on the CAN bus, diagnosis of the high-voltage battery and control of the coolant pump of the high-voltage battery 

The energy management of the entire battery system is carried out by external control (gateway). Strictly speaking, Porsche has designed a very complex energy management strategy around the entire vehicle and coordinated with the driving control of the entire vehicle. For example, the emergency management approach below is designed and controlled from the perspective of the entire vehicle. 

Figure 4 Vehicle energy management 

The reason why Taycan's EPA range is relatively low is mainly because a lot of margin is taken into consideration here. The design below requires immediate charging at 7%, and these control points are made relatively conservative. 

Figure 5 Emergency mode and system management

02. CMU Design

Before CMU, as shown below, this module (with 12 cells inside) is connected in series and then in parallel. The nominal voltage of each cell is 3.65V and the capacity is 66Ah. After configuration, the module voltage is 22V and the module capacity is 132Ah.