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

2.2.1 Inductor Design

In any power converter design, the inductor design is the most important part. The four important characteristics pertaining to the inductor design are namely the inductance value, ripple current, saturation current and the DC resistance (DCR).

Normally, the value of inductance can be calculated with Equation 7

Equation 7. L ≥ V i n × V o u t - V i n Δ i L p k - p k × f s w × V o u t

where,

  • Vout is the output voltage of the boost converter
  • Vin is the input voltage of the boost converter
  • fsw is the switching frequency of the converter
  • iL is the inductor ripple current

Hence, the inductor ripple can also be given by Equation 8

Equation 8. Δ i L ( p k - p k ) ≥ V i n × ( V o u t - V i n ) L × f s w × V o u t

where,

  • Vout is the output voltage of the boost converter
  • Vin is the input voltage of the boost converter
  • L is the value of inductance
  • fsw is the switching frequency

The worst-case duty cycle for a boost converter or a single-phase converter is can be seen from Figure 1-3, to be at 25%. Hence the inductance value is calculated for the corresponding condition. Normally, it is advisable to work with an inductor peak-to-peak current of less than 40% of the average inductor current for maximum output current. A smaller ripple from a larger valued inductor reduces the magnetic hysteresis losses in the inductor and EMI. The saturation current of the inductor must be higher than the calculated peak inductor current.

In a boost regulator, the inductor DC current can be calculated by Equation 9

Equation 9. I L - D C = V o u t × I o u t V i n × η

where,

  • Vout is the output voltage of the boost converter
  • Iout is the output current of the boost converter
  • Vin is the input voltage of the boost converter
  • η is the power conversion efficiency

Therefore, the inductor peak current is calculated with Equation 14,

Equation 10. i L - p k = i L - D C + Δ i L ( p k - p k ) 2

where,

iL(pk-pk) is the peak-to-peak inductor current ripple