FTM Board Club
STMicroelectronics
STDES-7KWOBC
7 kW on-board charger (OBC) reference design

The STDES-7KWOBC is an on-board charger (OBC) reference design which allows charging the battery of electric vehicles (EV) through your home AC mains plug or a private/public outlet (AC charging station).

The reference design embeds two sections: an interleaved totem pole PFC with SiC and a dual galvanic isolated LLC DC-DC ZVS resonant converter, based on MDmesh DM6 super-junction power MOSFETs. 

The power platform is a 7 kW module able to deliver a constant current (CC) or constant voltage (CV) on the output to be used as standalone (1 PH+ N), in parallel or in 3-phase mode (3Ph + N) to reach 21 kW.
The underlying insulated metal substrate on aluminum base plate enables very effective heat dissipation, forced or liquid cooling.  

Each module composing the reference design allows an easy interconnection among modules of the same type through wires or bus bar connection, reaching a higher output power. 

This reference design key factor is the efficiency and high-power density gained thanks to SiC and SJ power MOSFETs, silicon and SiC diodes, gate drivers, the SPC58NN84E7 power architecture automotive-grade microcontroller, and SCR thyristors for inrush current limitation. 

The STDES-7KWOBC is a fully assembled kit developed for performance evaluation only, not available for sale.

Features
  • Front end PFC stage using 2-channel interleaved totem pole topology operating at 70 kHz
  • Digital inrush current control
  • DC-DC stage using FB LLC resonant topology with 140 kHz resonant frequency
  • Constant current and constant voltage mode
  • Control stage based on SPC58NN84E7
  • 12 V input supply voltage galvanically isolated from output voltage GND (high voltage battery)
  • Bus bar interconnection possibility
  • RoHs compliant
  • PFC:
    • Key products: TN3050H-12GY-TR SCRs, STBR3012G2Y bypass diodes, SCTH35N65G2V-7AG SiC power MOSFET
    • Input: 85 to 265 VAC, 45 to 65 Hz
    • Digital inrush current limiter
    • Max. input current: 32 Arms
    • Switching frequency: 70 kHz
    • Average current mode control in continuous conduction mode (CCM)
    • PID or 2p2z 2x independent current loop regulators
    • PID or 2p2pz voltage regulator
    • SPC58NN84E7 MCU controller
  • DC-DC:
    • Key products: STH47N60DM6-7AG power MOSFET, STPSC20065GY-TR output diodes, A6387 gate driver
    • Output voltage: 250 to 450 VDC
    • Switching frequency: 92 to 250 kHz with start-up at 350 kHz
    • Two independent current loops (CC)
    • One voltage loop plus current balancing (CV)
    • PID regulators
    • SPC58NN84E7 MCU controller