TIDUF63 December   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 PV or Battery Input With DC/DC Converter
    2. 1.2 Isolation and CLLLC Converter
    3. 1.3 DC/AC Converter
    4. 1.4 Key System Specifications
  8. 2System Design Theory
    1. 2.1 Boost Converter Design
    2. 2.2 MPPT Operation
    3. 2.3 CLLLC Converter Design
      1. 2.3.1 Achieving Zero Voltage Switching (ZVS)
      2. 2.3.2 Resonant Tank Design
    4. 2.4 DC/AC Converter Design
  9. 3System Overview
    1. 3.1 Block Diagram
    2. 3.2 Design Considerations
      1. 3.2.1 DC/DC Converter
        1. 3.2.1.1 Input Current and Voltage Senses and MPPT
        2. 3.2.1.2 Inrush Current Limit
      2. 3.2.2 CLLLC Converter
        1. 3.2.2.1 Low-Voltage Side
        2. 3.2.2.2 High-Voltage Side
      3. 3.2.3 DC/AC Converter
        1. 3.2.3.1 Active Components Selection
          1. 3.2.3.1.1 High-Frequency FETs: GaN FETs
          2. 3.2.3.1.2 Isolated Power Supply
          3. 3.2.3.1.3 Low-Frequency FETs
        2. 3.2.3.2 Passive Components Selection
          1. 3.2.3.2.1 Boost Inductor Selection
          2. 3.2.3.2.2 Cx Capacitance Selection
          3. 3.2.3.2.3 EMI Filter Design
          4. 3.2.3.2.4 DC-Link Output Capacitance
        3. 3.2.3.3 Voltage and Current Measurements
    3. 3.3 Highlighted Products
      1. 3.3.1  TMDSCNCD280039C - TMS320F280039C Evaluation Module C2000™ MCU controlCARD™
      2. 3.3.2  LMG3522R050 - 650-V 50-mΩ GaN FET With Integrated Driver
      3. 3.3.3  LMG2100R044 - 100-V, 35-A GaN Half-Bridge Power Stage
      4. 3.3.4  TMCS1123 - Precision Hall-Effect Current Sensor
      5. 3.3.5  AMC1302 - Precision, ±50-mV Input, Reinforced Isolated Amplifier
      6. 3.3.6  AMC3330 - Precision, ±1-V Input, Reinforced Isolated Amplifier With Integrated DC/DC Converter
      7. 3.3.7  AMC1311 - High-Impedance, 2-V Input, Reinforced Isolated Amplifier
      8. 3.3.8  ISO6741 - General-Purpose Reinforced Quad-Channel Digital Isolators with Robust EMC
      9. 3.3.9  UCC21540 - Reinforced Isolation Dual-Channel Gate Driver
      10. 3.3.10 LM5164 - 100-V Input, 1-A Synchronous Buck DC/DC Converter with Ultra-low IQ
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Test Setup
      1. 4.2.1 DC/DC Board
      2. 4.2.2 DC/AC Board
    3. 4.3 Test Results
      1. 4.3.1 Input DC/DC Boost Results
      2. 4.3.2 CLLLC Results
      3. 4.3.3 DC/AC Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author
3.2.3.2.3 EMI Filter Design

The following EMI filter was designed to attenuate both the differential-mode and common-mode noise injected into the grid.

The EMI filter can be analyzed in the common-mode and differential-mode domains. From the EMI filter shown in Figure 3-13, it is possible to derive the equivalent common- and differential-mode circuits as shown respectively in parts a) and b), where Lσ represents the leakage inductance of the common-mode choke.

GUID-20231206-SS0I-2J7G-ZGHF-XHVL7WPQSD6B-low.svg
a) Equivalent differential-mode model
b) Equivalent common-mode model
Figure 3-13 EMI Filter

The first critical frequency to be attenuated is the 250 kHz. The 125 kHz was not considered because that value is not in the EMI mask.

Differential-Mode Attenuation at 250 kHz 84 dB
Common-Mode Attenuation at 250 kHz 84 dB

An EMI filter with the values listed in Table 3-1 was designed:

Table 3-1 EMI Filter Values
PARAMETER VALUE
L1 110 μH
C1 2.2 μF
Lcm1 Lcm 6 mH, Lσ 6 μH
C2 1 μF
Lcm2 Lcm 6 mH, Lσ 6 μH
Cy1 and Cy2 2.2 nF

Two Bourns 47690 (D6744) CMCs were used in this EMI filter.