Chargers from 50 kW to 350 kW
Design systems for high-power EV fast chargers
As electro mobility increasingly becomes part of our daily lives, the need for more efficient charging solutions grows. This translates to greater demand for higher charging power and fast charging stations. Establishing public charging infrastructure with high power levels can help meet these demands. With an eye on the requirements and technological developments in this field, you are challenged to respond with smart power conversion and management solutions for the charging networks of today and tomorrow.
Rising demands of public charging stations
Currently, public charging stations provide power of up to 150 kW in a single installation. In a charging park, a medium voltage transformer from 10 kV to 30 kV is a key component. It uses high-power chargers with up to 350 kW output power each. In this arrangement, all chargers can provide full power simultaneously by using non-isolated topology in each charger.
Selecting the right components
When choosing the ideal power semiconductor it is important to know the charger’s power level. Ultimately, the selection of suitable devices depends on this factor. Chargers in a power range above 50 kW are commonly built using Infineon’s IGBTs and CoolSiC™ MOSFETs and diode power modules, such as CoolSiC™ Easy Module, IGBT EconoPACK™ and the IGBT EconoDUAL™ family. With subunits from 50 kW to 100 kW, chargers with power ranges higher than 100 kW are built by stacking the subunits.
Our high-quality portfolio of power switches seamlessly works with the Rectifier Diode module. All switches need a driver and all drivers need to be controlled. That is why we also offer the best-fit EiceDRIVER™ as well as XMC™ and AURIX™ microcontrollers for your fast EV charging designs. Discover our line of OPTIGA™ products to ensure data protection and security.
The aim of high power chargers is to decrease the charging time to make electric vehicles on par with combustion engine cars. There are two possible charging infrastructure architectures: either isolate the primary AC side or the secondary DC side.
Isolating the primary AC side
In case of a charging park, 6 to 8 high power charging stations can be made available in an overall power setup of 2 MW to 3 MW, as proven in practice. Power is sourced from a medium voltage transformer, typically 22 kV to 500 V, to isolate the AC side of the system. The AC to DC stage follows, which may or may not involve an active rectifier. Multi-pulse passive rectification is one option. In this case, it’s possible to achieve the required input current harmonics of 5% to 7%. A highly efficient MW voltage transformer (around 99%) can be used to reduce overall system complexity. Isolating the primary side gives the designer freedom to use non-isolated DC-DC converter topologies for the DC-DC conversion stage. Usually, a multiphase buck converter is suitable for this architecture, with a DC conversion block.
Isolating the secondary DC side
The second infrastructure architecture reaches 350 kW by stacking 50 kW or 100 kW subunits for standalone applications.
The AC-DC system comes after an EMI filter, converts AC into DC voltage and usually has a controlled rectifier. The DC-DC conversion stage is shown in two systems: DC voltage to high frequency AC voltage on the isolation transformer’s primary side, and high frequency AC to DC voltage rectification on the secondary side.
The common strategy in this power category is to use power modules instead of discrete devices. IGBT-based solutions featuring EconoPACK™ and EconDUAL™ are perfect for both Vienna Rectifier and AFE, for AC-DC conversion, usually operating at around 20 kHz. CoolSiC™ Easy modules enable the AC-DC converter stage to operate at around 40 kHz to 50 kHz.