TIDUFC8 July   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Introduction
      2. 2.2.2 Basic Operation Principles and ZVS Requirements
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC27288
      2. 2.3.2 UCC23513
      3. 2.3.3 TMS320F2800137
      4. 2.3.4 TLV9062
      5. 2.3.5 INA181
      6. 2.3.6 TPSM861252
      7. 2.3.7 AMC0311R
  9. 3System Design Theory
    1. 3.1 Design Theory
      1. 3.1.1 Resonant Tank Design
      2. 3.1.2 Full-Range ZVS Realization
      3. 3.1.3 Total Control Algorithm
      4. 3.1.4 Resonant Tank RMS Current Analysis
    2. 3.2 Hardware Design Theory
      1. 3.2.1 Resonant Capacitors
      2. 3.2.2 Power Stage
      3. 3.2.3 Voltage Sensing
      4. 3.2.4 Current Sensing
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
      1. 4.2.1 Simulation
    3. 4.3 Test Setup
    4. 4.4 Test Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Layout Prints
    2. 5.2 Tools
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

3.1.1 Resonant Tank Design

The design of the DBSRC resonant tank is one of the most critical parts of the resonant converter. When designing the resonator, the first thing to consider is the design of the resonant frequency, which determines the approximate range of the switching frequency.

Since the switching frequency affects the volume of the passive components in one respect, and the switching loss of the system from another perspective, the resonant frequency fr is selected as 80kHz after considering these two factors.

For the effective value of the resonator current, different resonant frequency and different combinations of resonant inductors and resonant capacitors do not affect the effective value of the resonator current under a certain load, which is analyzed in the following sections.

The smaller the resonant capacitor, the greater the voltage on the capacitor. The cost of the capacitor increases, and then after comprehensive consideration, the resonant inductance 2.1μH is selected, and the resonant capacitance is 1600nF. In the topological circuit diagram in Figure 3-1, the resonant capacitance (Cr) is composed of the primary side C1, C2 and the secondary side C3 and C4, as in Equation 1.

Equation 1. C r = 1 1 C 1 + C 2 + 1 n 2 × ( C 3 + C 4 )

where

  • C1 = C2 = C3 = C4 = 1000nF
  • n is transformer ratio = 2

At this point, the peak-to-peak voltage on the capacitor is less than 100V.