Shanghai Belling in the automotive DC charging pile charging module application product solutions

I. Overview

With the rapid development of new energy vehicle technology, the penetration rate of terminal applications is increasing rapidly, and in the foreseeable future, the scale of the entire new energy vehicle market will continue to expand and move towards the stage of large-scale and high-quality development. Charging pile as an important part of the new energy vehicle industry chain, accelerating the construction and improvement of charging pile supporting facilities is crucial to alleviate the anxiety of charging and promote the deeper popularization of electric vehicles. In order to meet the fast and safe charging needs of users, improving the power level and efficiency of charging piles is the mainstream direction of its development.

Second, the working principle and topology of DC charging module

The DC charging pile is connected to the power grid, and after the rectification and voltage boost, the output can be adjusted direct current to charge the power battery. It has the characteristics of wide voltage regulation range, high output power, fast charging speed, etc., and has been widely used. Its overall structure block diagram is shown in Figure 1. The power part is composed of multiple DC charging modules in parallel. As the power of DC charging pile continues to increase, the power level of its charging module also increases, gradually increasing from the mainstream 20kW/30kW to 40kW/50kW and above. The system block diagram is shown in Figure 2.

Figure 1 DC charging pile structure block diagram

Source: Thoughts on thermal design of charging pile
Figure 2 Block diagram of DC charging pile system

The power circuit of the DC charging module consists of AC/DC and DC/DC. The AC/DC part is connected to the power grid side for rectification and power factor correction; The DC/DC part outputs adjustable DC voltage to meet the charging requirements of different types of batteries.
Figure 3 DC charging module structure diagram

The topology of a typical unidirectional DC charging module is shown in Figure 4. AC/DC part adopts three-phase Vienna PFC, which can effectively reduce the voltage stress of power devices, high switching frequency, effectively reduce the volume of magnetic devices, and improve the power density of the system. The DC/DC part adopts the LLC topology of primary side series and secondary side interleaving parallel, which can realize the ZVS of primary side and ZCS of secondary side, reduce the system loss and improve the charging efficiency.
Figure 4. Typical topology of DC charging module

With the development of V2G, V2X and other technologies, DC charging piles need to achieve two-way flow of energy to help the higher quality development of the new energy industry. A typical bidirectional topology is shown in Figure 5, with 1200V power devices available for both front and rear stages. In this application, the high voltage MOSFETs will exhibit excellent device characteristics.
图5 双向直流充电模块典型拓扑结构