EV Charging Solution

SiC MOSFET advantages vs IGBTs: (1) No reverse recovery: zero Qrr eliminates diode reverse recovery losses

(2) Low switching losses: 80% reduction enables 100kHz+ high frequency operation

(3) Low on-resistance: Rds(on) has small temperature variation, efficiency advantage at high temperature

(4) High efficiency: system efficiency up to 99%, 2-3 percentage points higher than IGBT

(5) Small size: high frequency reduces magnetic component size by 60%

(6) Simple cooling: high efficiency reduces cooling requirements

(7) High reliability: SiC material characteristics suitable for high temperature and high voltage. Fuji FMF800DX-24A (1200V) and FMF400HX-12A (650V) are ideal for EV chargers.

Choose SiC for high efficiency and power density; IGBT for cost-sensitive applications with lower power density requirements.

EV charger PFC circuit design points: (1) Topology selection: below 30kW can use single-phase or interleaved Boost PFC

above 30kW recommend three-phase Vienna rectifier or totem-pole bridgeless PFC

(2) Switching devices: use SiC MOSFET (FMF400HX-12A) or super-junction MOSFET as switches

(3) Switching frequency: SiC solution 65-100kHz, IGBT solution 15-30kHz

(4) Inductor design: consider current ripple and core losses, recommend iron-silicon-aluminum powder core

(5) Control loop: voltage loop bandwidth <10Hz, current loop bandwidth <5kHz

(6) EMI filter: install three-phase EMI filter on input side

(7) Soft start: limit starting current to protect devices. Fuji SiC solution can achieve 99%+ PFC efficiency.

Below 30kW use single-phase Boost PFC; above 30kW use three-phase Vienna or totem-pole PFC; choose SiC for ultimate efficiency.

LLC resonant converter design points: (1) Resonant frequency: typically 100-200kHz to leverage SiC high-frequency advantages

(2) Transformer design: use planar core to reduce height and leakage inductance, improve efficiency

(3) Resonant inductor: can be integrated in transformer using leakage inductance

(4) Dead time: precise control to ensure ZVS, typically 200-500ns

(5) Gain range: design sufficient gain range for input voltage and load variations

(6) Rectifier diodes: use SiC Schottky diodes to eliminate reverse recovery losses

(7) Control strategy: use variable frequency control, burst mode at light load. Fuji SiC MOSFET's low output capacitance benefits ZVS implementation.

Choose LLC for isolated applications; resonant frequency 100-200kHz; use SiC diodes for rectification.

Fuji EV charger solution supports 200V-1000V wide voltage output: (1) Voltage range: through LLC variable frequency control for wide voltage regulation covering all EV battery voltages

(2) Charging standards: support GB/T (China), CCS Combo (Europe), CHAdeMO (Japan) and other standards

(3) BMS communication: CAN bus communication with vehicle BMS, dynamic output adjustment based on battery needs

(4) Power allocation: multi-gun design supports intelligent power allocation improving equipment utilization

(5) Charging curve: optimal charging curve based on battery characteristics to protect battery life

(6) Safety protection: overvoltage, overcurrent, overtemperature, insulation monitoring and other protections. Solution has passed compatibility testing with multiple mainstream automakers.

Public charging stations support multiple standards; dedicated scenarios can choose single standard; new projects prioritize GB/T and CCS standards.

EV charger cooling solution selection: (1) Below 30kW: can use forced air cooling, simple design and low cost

(2) 30-120kW: recommend intelligent air cooling, adjusting fan speed based on temperature to balance cooling and noise

(3) Above 120kW: recommend liquid cooling, power density up to 6kW/L+, low noise

(4) SiC solution: due to high efficiency and low losses, can simplify cooling design, 30kW modules can use natural or light forced air cooling

(5) Liquid cooling design: use deionized water coolant, flow rate 10-20L/min, inlet temperature 40°C

(6) Thermal management: intelligent temperature control system, dynamically adjusting cooling capacity based on module temperature. Fuji solutions provide both air and liquid cooling reference designs.

Power density >4kW/L consider liquid cooling; cost-sensitive choose air cooling; SiC solutions can simplify cooling design.

EV charger EMC design requirements: (1) Standards compliance: meet GB/T 18487.2 and CISPR 11 Class B standards

(2) Input filtering: three-phase EMI filters to suppress common mode (100kHz-30MHz) and differential mode (150kHz-30MHz) interference

(3) Output filtering: filter ferrite rings at charging gun output to suppress high frequency noise

(4) Shielding design: power module metal enclosure grounded for shielding

(5) Grounding system: power ground connected to chassis through Y capacitors single point, control ground separate

(6) Cable shielding: charging gun cables use shielded wire with both ends grounded

(7) Margin: recommend 10-15dB margin to avoid later corrections. Early EMC pre-testing is recommended.

Public chargers must meet Class B standard; reserve EMC correction margin; early EMC pre-testing recommended.