3kW Full-Bridge LLC Resonant Digital Power Supply Evaluation Kit

The STEVAL-DPSLLCK1 from STMicroelectronics is a digitally-controlled 3kW full-bridge LLC resonant dc-dc converter with output synchronous rectification. The kit consists of a power board, digital control board, adapter board, and firmware modules.

The full -ridge primary section of the LLC converter is based on MDmesh™ DM2 Power MOSFETs for high efficiency performance. The pwm switching frequency is digitally controlled to regulate the output voltage. The converter operates at near resonant frequencies to maximize efficiency and achieve Zero Voltage Switching (ZVS) over the entire operating range.

The HF transformer provides galvanic isolation and magnetic integration of the inductive elements for a compact design.

Synchronous rectification (SR) with STripFET™ F7 Power MOSFETs is employed on the secondary side to reduce conduction losses.

The STM32F334 microcontroller on the digital control board embeds a high resolution timer for finer regulation and can communicate status information via USART, CAN, SMBus, and opto-coupled serial communication.

STEVAL-DPSLLCK1 topology (click on image to enlarge)

Both the primary and secondary sections are supplied by an off-line flyback circuit based on VIPer27HD which provides regulated voltages to the control board, the gate driver ICs and the signal conditioning circuits.

Users can connect a PFC to the power board and extend communication and interfacing with the supplied adapter board.

STEVAL-DPSLLCK1

Summary of key features:

• Power ratings:
  • input dc voltage: 375V to 425V
  • output voltage: 48V
  • maximum output current: 62.5A
  • output power: 3kW
  • peak efficiency: 95.3%
• HF transformer isolation voltage: 4kV
• Resonant and switching frequencies:
  • max dc-dc switching frequency: 380kHz (at startup)
  • closed loop switching frequency: 120kHz to 250kHz
  • resonant frequency: 175kHz
• Protection mechanisms:
  • undervoltage and overvoltage protection on input and output
  • overtemperature protection
  • short-circuit protection
  • forced cooling with air flow speed modulation according to the output power and temperature
• Efficiency:
  • adaptive synchronous rectification
  • light load burst mode
• Digital control with STM32F334 microcontroller

STEVAL-DPSLLCK1 block diagram (click on image to enlarge)