TIDUF64A December   2023  – August 2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
    2. 1.2 PV Input with Boost Converter
    3. 1.3 Bidirectional DC/DC Converter
    4. 1.4 DC/AC Converter
  8. 2System Design Theory
    1. 2.1 Boost Converter
      1. 2.1.1 Inductor Design
      2. 2.1.2 Rectifier Diode Selection
      3. 2.1.3 MPPT Operation
    2. 2.2 Bidirectional DC/DC Converter
      1. 2.2.1 Inductor Design
      2. 2.2.2 Low-Voltage Side Capacitor
      3. 2.2.3 High-Voltage Side Capacitor
    3. 2.3 DC/AC Converter
      1. 2.3.1 Boost Inductor Design
      2. 2.3.2 DC-Link Capacitor
  9. 3System Overview
    1. 3.1 Block Diagram
    2. 3.2 Design Considerations
      1. 3.2.1 Boost Converter
        1. 3.2.1.1 High-Frequency FETs
        2. 3.2.1.2 Input Voltage and Current Sense
      2. 3.2.2 Bidirectional DC/DC Converter
        1. 3.2.2.1 High-Frequency FETs
        2. 3.2.2.2 Current and Voltage Measurement
        3. 3.2.2.3 Input Relay
      3. 3.2.3 DC/AC Converter
        1. 3.2.3.1 High-Frequency FETs
        2. 3.2.3.2 Current Measurements
        3. 3.2.3.3 Voltage Measurements
        4. 3.2.3.4 Auxiliary Power Supply
        5. 3.2.3.5 Passive Components Selection
    3. 3.3 Highlighted Products
      1. 3.3.1  TMDSCNCD280039C - TMS320F280039C Evaluation Module C2000™ MCU controlCARD™
      2. 3.3.2  LMG3522R030 650-V 30-mΩ GaN FET With Integrated Driver, Protection and Temperature Reporting
      3. 3.3.3  TMCS1123 - Precision Hall-Effect Current Sensor
      4. 3.3.4  AMC1302 - Precision, ±50-mV Input, Reinforced Isolated Amplifier
      5. 3.3.5  ISO7741 Robust EMC, Quad-channel, 3 Forward, 1 Reverse, Reinforced Digital Isolator
      6. 3.3.6  ISO7762 Robust EMC, Six-Channel, 4 Forward, 2 Reverse, Reinforced Digital Isolator
      7. 3.3.7  UCC14131-Q1 Automotive, 1.5-W, 12-V to 15-V VIN, 12-V to 15-V VOUT, High-Density > 5-kVRMS Isolated DC/DC Module
      8. 3.3.8  ISOW1044 Low-Emissions, 5-kVRMS Isolated CAN FD Transceiver With Integrated DC/DC Power
      9. 3.3.9  ISOW1412 Low-Emissions, 500kbps, Reinforced Isolated RS-485, RS-422 Transceiver With Integrated Power
      10. 3.3.10 OPA4388 Quad, 10-MHz, CMOS, Zero-Drift, Zero-Crossover, True RRIO Precision Operational Amplifier
      11. 3.3.11 OPA2388 Dual, 10-MHz, CMOS, Zero-Drift, Zero-Crossover, True RRIO Precision Operational Amplifier
      12. 3.3.12 INA181 26-V Bidirectional 350-kHz Current-Sense Amplifier
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Note
    3. 4.3 Test Setup
      1. 4.3.1 Boost Stage
      2. 4.3.2 Bidirectional DC/DC Stage - Buck-Mode
      3. 4.3.3 DC/AC Stage
    4. 4.4 Test Results
      1. 4.4.1 Boost Converter
      2. 4.4.2 Bidirectional DC/DC Converter
        1. 4.4.2.1 Buck Mode
        2. 4.4.2.2 Boost Mode
      3. 4.4.3 DC/AC Converter
  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 Authors
  13. 7Revision History

3.2.3.4 Auxiliary Power Supply

An auxiliary power supply for the GaN FETs, operation amplifiers, relays, isolated amplifiers, digital circuitry, and so on for the entire system is generated using UCC28710 in buck configuration. The idea is that, on start-up of a string inverter, the input voltage from the strings which appears across the DC bus when reaches a certain value, enables the operation of the UCC28710 buck controller and produces a 12V supply. This is a non-isolated topology, since the MCU also sits on the DC Bus-. The VS sense is set by the resistors R93 and R95 to have an output of 12V. And the current sense is set with the resistors R96, R97 and R98. It is important to keep in mind the peak current and DC current rating of the inductor L13 to have the necessary load current requirements of the circuitry satisfied.

Figure 3-10 shows the power supply schematic.

TIDA-010938 Auxiliary Power Supply Design Figure 3-10 Auxiliary Power Supply Design

Furthermore, as required by other components on the board, a buck converter TPS56020 was to convert the 12V rail to a 5V rail and an LDO TLV75533 was used to convert the 5V rail to a 3V3 rail.