Benchmarking C4D40120D, 1200V SiC Schottky diode B2D40120HC1 makes on-board charger more efficient

The on-board charger is the core component of electric vehicles. 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. As shown in the figure:

On-board charger charging block diagram

Traditional Si devices can no longer meet the growing performance requirements of on-board chargers due to their voltage resistance and switching frequency limitations. SiC devices with high voltage resistance, low loss and high-speed switching characteristics are gradually replacing Si devices and becoming the mainstream application of on-board chargers.

Below we take a 6.6kW on-board charger as an example to introduce the application of Basic Semiconductor's SiC Schottky diode B2D40120HC1 in the charger's AC-DC and DC-DC circuits:

1. AC-DC circuit

The input voltage of the on-board charger is usually 220V AC. The AC-DC can adopt a bridgeless PFC topology circuit, which can improve the power factor and obtain a wide range (400~800V) of bus voltage, as shown in the following figure:

Application of SiC diode in bridgeless PFC circuit

2. DC-DC circuit

For safety reasons, the on-board charger requires electrical isolation between the charging pile and the battery, which requires the use of an isolation transformer to achieve energy transfer. Currently, the commonly used topology is LLC resonance, as shown in the following figure:

Application of SiC diodes in LLC circuits

In the above PFC circuit and LLC circuit, the smaller the conduction loss and switching loss of the diode, the smaller the reverse leakage current and reverse recovery time, the higher the switching frequency can be. The higher the reverse withstand voltage, the higher the operating voltage can be selected, and the higher the efficiency.

Basic Semiconductor's SiC Schottky diode B2D40120HC1 achieves an extremely short reverse recovery time (trr close to zero) that Si fast recovery diodes cannot achieve, with a reverse recovery current of ≤5uA (at Vr=1200V, Tj=25℃), a withstand voltage of up to 1200V, and a junction temperature of up to 175℃. It can effectively reduce switching losses and increase switching frequency, which is crucial for reducing heat generation, increasing operating voltage, energy density, and efficiency of on-board chargers.

In addition, B2D40120HC1 can be directly compatible with many brand devices on the market, such as Cree C4D40120D, Rohm SCS240KE2, Infineon IDW40G120C5B, STMicroelectronics STPSC40H12CWL, and ON Semiconductor FFSH40120ADN-F155, to ensure performance.