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

4.4.2.2 Boost Mode

Figure 4-8 and Table 4-3 show the efficiency of the bidirectional DC/DC converter functioning in boost mode at 400V DC-link output. The input battery voltages considered are 80V, 160V, 240V, and 320V and the table shows that the converter achieves peak efficiencies of 97.7%, 98.8%, 99.3% and 99.5% respectively.

TIDA-010938 Bidirectional DC/DC Efficiency in Boost Mode Figure 4-9 Bidirectional DC/DC Efficiency in Boost Mode
Table 4-3 Bidirectional DC/DC Efficiency in Boost Mode
OUTPUT POWER EFFICIENCY AT VBat=80 V OUTPUT POWER EFFICIENCY AT VBat=160 V OUTPUT POWER EFFICIENCY AT VBat=240 V OUTPUT POWER EFFICIENCY AT VBat=320 V
0.1kW 95.6% 0.2kW 97.0% 0.6kW 98.7% 0.8kW 99.1%
0.2kW 96.4% 0.5kW 98.3% 1.0kW 99.0% 1.3kW 99.3%
0.4kW 97.0% 0.9kW 98.5% 1.6kW 99.1% 2.1kW 99.4%
0.6kW 97.1% 1.2kW 98.8% 2.0kW 99.2% 2.7kW 99.4%
0.7kW 97.3% 1.8kW 98.6% 2.5kW 99.2% 3.4kW 99.4%
0.9kW 97.6% 2.1kW 98.8% 3.0kW 99.2% 4.0kW 99.5%
1.0kW 97.6% 2.5kW 98.8% 3.4kW 99.3% 4.5kW 99.5%
1.2kW 97.6% 2.8kW 98.8% 4.0kW 99.2% 5.3kW 99.5%
1.4kW 97.7% 3.1kW 98.8% 4.4kW 99.2% 5.9kW 99.4%
1.5kW 97.6% 3.4kW 98.8% 5.0kW 99.2% 6.6kW 99.4%
1.7kW 97.6% 3.7kW 98.7% 5.4kW 99.2% 7.2kW 99.4%
1.8kW 97.4% 4.1kW 98.6% 5.8kW 99.2%
2.0kW 97.3% 4.4kW 98.6% 6.4kW 99.1%
2.2kW 97.0% 4.5kW 98.5% 6.9kW 99.0%
2.4kW 96.8%

The results for the boost mode are similar to that of buck mode, however the losses at low power are higher, hence the efficiency is lower. This is due to the boosting operation, and higher losses of the GaN FET when boosting up to a higher voltage.

Figure 4-10 shows the voltage of the switching node of one of the legs during operation of the converter in Boost mode. From the picture, observe the sharp switching edges without overshoot and ringing. A rise-time of around 30ns can be observed.

TIDA-010938 Bidirectional DC/DC Switching Node in Boost Mode Figure 4-10 Bidirectional DC/DC Switching Node in Boost Mode

The GaN junction temperature for the can be seen in Figure 4-11. The other GaNs have a similar temperature profile. This operation corresponds to a conversion of VBat of 240V to a DC-link voltage of 400V. The temperature does not go higher than 70°C.

TIDA-010938 GaN v/s Heatsink Temperature for Bidirectional DC/DC Converter Figure 4-11 GaN v/s Heatsink Temperature for Bidirectional DC/DC Converter