TIDUF18A October   2022  – February 2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1 CLLLC System Description
    1. 1.1 Key System Specifications
  8. 2 CLLLC System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations and System Design Theory
      1. 2.2.1 Tank Design
        1. 2.2.1.1 Voltage Gain
        2. 2.2.1.2 Transformer Gain Ratio Design (NCLLLC)
        3. 2.2.1.3 Magnetizing Inductance Selection (Lm)
        4. 2.2.1.4 Resonant Inductor and Capacitor Selection (Lrp and Crp)
      2. 2.2.2 Current and Voltage Sensing
        1. 2.2.2.1 VPRIM Voltage Sensing
        2. 2.2.2.2 VSEC Voltage Sensing
        3. 2.2.2.3 ISEC Current Sensing
        4. 2.2.2.4 ISEC TANK and IPRIM TANK
        5. 2.2.2.5 IPRIM Current Sensing
        6. 2.2.2.6 Protection (CMPSS and X-Bar)
      3. 2.2.3 PWM Modulation
  9. 3 Totem Pole PFC System Description
    1. 3.1 Benefits of Totem-Pole Bridgeless PFC
    2. 3.2 Totem-Pole Bridgeless PFC Operation
    3. 3.3 Key System Specifications
    4. 3.4 System Overview
      1. 3.4.1 Block Diagram
    5. 3.5 System Design Theory
      1. 3.5.1 PWM
      2. 3.5.2 Current Loop Model
      3. 3.5.3 DC Bus Regulation Loop
      4. 3.5.4 Soft Start Around Zero-Crossing for Eliminating or Reducing Current Spike
      5. 3.5.5 Current Calculation
      6. 3.5.6 Inductor Calculation
      7. 3.5.7 Output Capacitor Calculation
      8. 3.5.8 Current and Voltage Sense
  10. 4 Highlighted Products
    1. 4.1 C2000 MCU TMS320F28003x
    2. 4.2 LMG352xR30-Q1
    3. 4.3 UCC21222-Q1
    4. 4.4 AMC3330-Q1
    5. 4.5 AMC3302-Q1
  11. 5 Hardware, Software, Testing Requirements, and Test Results
    1. 5.1 Required Hardware and Software
      1. 5.1.1 Hardware Settings
        1. 5.1.1.1 Control Card Settings
      2. 5.1.2 Software
        1. 5.1.2.1 Opening the Project Inside Code Composer Studio
        2. 5.1.2.2 Project Structure
    2. 5.2 Testing and Results
      1. 5.2.1 Test Setup (Initial)
      2. 5.2.2 CLLLC Test Procedure
        1. 5.2.2.1 Lab 1. Primary to Secondary Power Flow, Open Loop Check PWM Driver
        2. 5.2.2.2 Lab 2. Primary to Secondary Power Flow, Open Loop CheckPWM Driver and ADC with Protection, Resistive Load Connected on Secondary
          1. 5.2.2.2.1 Setting Software Options for Lab 2
          2. 5.2.2.2.2 Building and Loading the Project and Setting up Debug Environment
          3. 5.2.2.2.3 Using Real-time Emulation
          4. 5.2.2.2.4 Running the Code
          5. 5.2.2.2.5 Measure SFRA Plant for Voltage Loop
          6. 5.2.2.2.6 Verify Active Synchronous Rectification
          7. 5.2.2.2.7 Measure SFRA Plant for Current Loop
        3. 5.2.2.3 Lab 3. Primary to Secondary Power Flow, Closed Voltage Loop Check, With Resistive Load Connected on Secondary
          1. 5.2.2.3.1 Setting Software Options for Lab 3
          2. 5.2.2.3.2 Building and Loading the Project and Setting up Debug Environment
          3. 5.2.2.3.3 Running the Code
          4. 5.2.2.3.4 Measure SFRA for Closed Voltage Loop
        4. 5.2.2.4 Lab 4. Primary to Secondary Power Flow, Closed Current Loop Check, With Resistive Load Connected on Secondary
          1. 5.2.2.4.1 Setting Software Options for Lab 4
          2. 5.2.2.4.2 Building and Loading the Project and Setting up Debug
          3. 5.2.2.4.3 Running the Code
          4. 5.2.2.4.4 Measure SFRA for Closed Current Loop
        5. 5.2.2.5 Lab 5. Primary to Secondary Power Flow, Closed Current Loop Check, With Resistive Load Connected on Secondary in Parallel to a Voltage Source to Emulate a Battery Connection on Secondary Side
          1. 5.2.2.5.1 Setting Software Options for Lab 5
          2. 5.2.2.5.2 Designing Current Loop Compensator
          3. 5.2.2.5.3 Building and Loading the Project and Setting up Debug
          4. 5.2.2.5.4 Running the Code
          5. 5.2.2.5.5 Measure SFRA for Closed Current Loop in Battery Emulated Mode
      3. 5.2.3 TTPLPFC Test procedure
        1. 5.2.3.1 Lab 1: Open Loop, DC
          1. 5.2.3.1.1 Setting Software Options for BUILD 1
          2. 5.2.3.1.2 Building and Loading Project
          3. 5.2.3.1.3 Setup Debug Environment Windows
          4. 5.2.3.1.4 Using Real-Time Emulation
          5. 5.2.3.1.5 Running Code
        2. 5.2.3.2 Lab 2: Closed Current Loop DC
          1. 5.2.3.2.1 Setting Software Options for BUILD 2
          2. 5.2.3.2.2 Designing Current Loop Compensator
          3. 5.2.3.2.3 Building and Loading Project and Setting Up Debug
          4. 5.2.3.2.4 Running Code
        3. 5.2.3.3 Lab 3: Closed Current Loop, AC
          1. 5.2.3.3.1 Setting Software Options for Lab 3
          2. 5.2.3.3.2 Building and Loading Project and Setting Up Debug
          3. 5.2.3.3.3 Running Code
        4. 5.2.3.4 Lab 4: Closed Voltage and Current Loop
          1. 5.2.3.4.1 Setting Software Options for BUILD 4
          2. 5.2.3.4.2 Building and Loading Project and Setting up Debug
          3. 5.2.3.4.3 Running Code
      4. 5.2.4 Test Results
        1. 5.2.4.1 Efficiency
        2. 5.2.4.2 System Performance
        3. 5.2.4.3 Bode Plots
        4. 5.2.4.4 Efficiency and Regulation Data
        5. 5.2.4.5 Thermal Data
        6. 5.2.4.6 PFC Waveforms
        7. 5.2.4.7 CLLLC Waveforms
  12. 6 Design Files
    1. 6.1 Schematics
    2. 6.2 Bill of Materials
    3. 6.3 Altium Project
    4. 6.4 Gerber Files
  13. 7 Software Files
  14. 8 Related Documentation
    1. 8.1 Trademarks
  15. 9 Terminology
  16. 10About the Author
  17. 11Revision History

3.2 Totem-Pole Bridgeless PFC Operation

The totem-pole PFC operates in the positive and negative cycles of the AC mains input, respectively, and determines the current flow depending on how the high frequency GaN MOSFETs are switched (see Figure 3-2 and Figure 3-3, respectively).

The high-frequency GaN MOSFETs together with the inductor create a synchronous mode boost converter. During the positive half cycle, S2 is the boost switch which is driven with duty cycle D and S1 is driven with a complementary pulse-width modulation (PWM) signal (1-D). Figure 3-2 (A) shows the direction in which the current flows. Similarly, during the period when S2 is switched with 1-D, S1 is switched with D; Figure 3-2 (B) shows the direction in which the current flows. Note that, during this cycle, SD2 conducts continuously.

During the negative half cycle, the operation is similar except that the role of the high-side- and low-side, high-frequency switches are swapped. Figure 3-3 shows the direction in which the current flows. Note that, during this cycle, SD1 conducts continuously.

GUID-2AF492FC-94E7-43E0-8047-9C9205B794B0-low.gifFigure 3-2 Totem-Pole Bridgeless PFC Operation During Positive Half Cycle: (A) While S2 is Switched ON (B) While S2 is Switched OFF
GUID-24E208C5-8C90-4FD6-8488-175BB6F5B74D-low.gifFigure 3-3 Totem-Pole Bridgeless PFC Operation During Negative Half Cycle: (A) While S1 is Switched ON (B) While S1 is Switched OFF

This reference design uses GaN FETs (LMG3522R030-Q1) and TI’s C2000™ Piccolo™ (TMS320F280039C) high-performance MCU. The high-frequency GaN FETs operate at a 120-kHz switching frequency and the pair of Si MOSFETs operate at the line frequency (approximately 45 Hz to 60 Hz). Thus the conduction path includes one GaN switch and one low-frequency Si switch with significantly-reduced conduction losses. The use of two-channel interleaving to reduce conduction loss and input current ripple. Test results demonstrate a high efficiency above 98.5%.