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Application of SiC devices in on-board charger

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The on-board charger is the core part of the electric vehicle,and its function is to dynamically adjust the charging current and voltage parameters according to the instructions of the battery management system to complete the charging process of the electric vehicle.

As a power electronic device.the power circuit of the on-board charger is mainly composed of AC-DC and DC-DC circuits.

With the continuous development of electric vehicle technology and people 'S increasing demand for charging efficiency,the performance of on-board chargers is also constantly improving.

Traditional Si can't meet the growing performance needs of on-board charger due to its voltage resistance and the limitations of switching frequency.

The SiC with high voltage resistance,low loss and high-speed switching are gradually replacing Si to be the mainstream application of on-board charger.

Here we will take the 6.6KW on-board charger as an example to introduce the application of the SiC Schottky Barrier Diode in the AC-DC and DC-DC.

The input voltage of the on-board charger is usually AC 220V AC-DC can use an active power factor to correct the PFC topology circuit.Increasing the power factor,a wide range (400~800V) bus voltage can be obtained at the same time.

For safety reasons,the charging pile and the battery are required to be electrically isolated,which need to use isolation DC-DC circuit to accomplish energy transfer.The topology usually used is LLC resonant circuit.

In the above of PFC and LLC circuits,the smaller the loss of conduction and switch of the diode,and the smaller time of the reverse leakage current and reverse voltage resistance,the higher switching frequency.

The higher reverse voltage resistance,the higher choice of operating voltage and higher efficiency.

SiC Schottky Barrier Diode accomplish the very short reverse recovery time(trr is close to zero) that Si diode can't do,which can effectively reduce switching loss and improve switching frequency.It is vital for on-board charger to reduce heat generation and improve operating voltage, energy density and efficiency.