Before the official release of the CTB battery system of the seal, let’s take a closer look at the battery system of dolphin E3.0. Before, I spent a lot of time collecting information and consulting to understand the follow-up battery iteration path of BYD.

From the perspective of cell, E3.0 is divided into two different configurations:

● the low mileage version is a newly developed 100Ah lithium iron phosphate battery cell, with a total power of 30.7kwh and a system voltage of 307.2v;

● the high mileage version adopts the first generation of 135ah lithium iron phosphate battery cell of blade battery. The total power is 44.9kwh, the rated voltage is 332.8v, and the energy density of the battery system is 140wh / kg.

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▲ Figure 1 Two different specifications of dolphin battery system

Dolphin E3.0 adopts the flat battery system, which is also a big difference between the subsequent E3.0 and the previous dynasty series. Not only the layout of blade cells is relatively perfect, but also the layout of electronic and electrical components can be optimized.

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▲ Figure 2 BYD dolphin battery system

Part 1

Battery arrangement

A beam stiffener is added in the middle of the lower box of 45kwh dolphin battery, but this thing is not seen in the 30kwh battery pack. I understand that due to the difference between Han EV and Han EV, they are all made into 1100mm wide battery system, which is arranged on A0 level trolley. The side impact pressure is relatively large, especially the positive and negative poles of the cell are on the side. Therefore, the shorter 100Ah does not need to be the middle beam, but directly made into a whole block, while the longer cell needs to be divided into two blocks.

Note: the two cells adopt the capacity configuration method with different lengths.

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▲ Figure 3 Differences in battery design between two different versions

14 fasteners are used for the connection between the battery system and the chassis of the whole vehicle. Dolphin optimizes both sides to make up for the weight brought by the increased beam. The whole lower shell realizes the reinforcement of the vehicle body through three beams.

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▲ Figure 4 Overall layout of dolphin battery

The design of dolphin E3 makes the PDU into a long strip, and a very narrow area is reserved in the lower shell to arrange high and low voltage electronic and electrical components.

Part 2

Interface and EE design

The battery management collection part of dolphin E3 battery system is placed inside the battery pack, including battery sampling and execution unit, BIC and battery sampling line. In the publicity, the battery management calculation part has been integrated into the three electric domain controller. In BDU, there is only one main positive and one main negative, and then do a precharge.

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▲ Figure 5 High voltage electrical components of dolphin battery system

As shown in the figure below, the high-voltage interface begins to be simplified and returns to the mode of fast charging management in the precursor system, which was the earliest leaf. There are few low-voltage connector harnesses on the left, so it is easier to take care of.

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▲ Figure 6 High voltage interface and direct cooling interface

From this figure, the BDU contains hvsu to control the contactor and complete four-way high-voltage acquisition, then cooperate with current sampling (this may be in hvsu), cooperate with BIC for communication, and then output through low-voltage connector. The main functions of BIC include single battery voltage sampling, battery temperature sampling, battery equalization, etc.

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▲ Figure 7 Dolphin battery system

In this battery pack, the direct cooling mode is adopted, so the heating problem is OK. In fact, BYD has reserved the heating film power supply mode (12V power supply). In fact, the whole interface has only one can, which is very simple here.

Reviewed and edited by: Li Qian

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