TIDUFD2 May   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Input Capacitors Selection
      2. 2.2.2 DC Side
      3. 2.2.3 AC Side
    3. 2.3 Highlighted Products
      1. 2.3.1 TMDSCNCD28P55X - controlCARD Evaluation Module
        1. 2.3.1.1 Hardware Features
        2. 2.3.1.2 Software Features
      2. 2.3.2 LMG2100R026 - 100V, 53A GaN Half-Bridge Power Stage
      3. 2.3.3 LMG365xR035 - 650V 35mΩ GaN FET With Integrated Driver and Protection
      4. 2.3.4 TMCS1123 - Precision 250kHz Hall-Effect Current Sensor With Reinforced Isolation
      5. 2.3.5 TMCS1133 - Precision 1MHz Hall-Effect Current Sensor With Reinforced Isolation
      6. 2.3.6 INA185 - 26V, 350kHz, Bidirectional, High-Precision Current Sense Amplifier
      7. 2.3.7 LM5164 – 100V Input, 1A Synchronous Buck DC-DC Converter With Ultra-Low IQ
      8. 2.3.8 ISO6762 – General-Purpose Six-Channel Reinforced Digital Isolators With Robust EMC
  9. 3System Design Theory
    1. 3.1 Isolation for Solar Inverters
    2. 3.2 Topology Overview
    3. 3.3 Control Theory
      1. 3.3.1 Single and Extended Phase Shift Modulation Technique
      2. 3.3.2 Zero Voltage Switching and Circulating Current
      3. 3.3.3 Optimized Control Method
      4. 3.3.4 Dead-Time Compensation
      5. 3.3.5 Frequency Modulation
      6. 3.3.6 Controller Block Diagram
    4. 3.4 MPPT and Input Voltage Ripple
  10. 4Hardware, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Test Setup
      1. 4.2.1 Board Check
      2. 4.2.2 DC-DC Tests
      3. 4.2.3 DC-AC Tests
    3. 4.3 Test 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

3.3 Control Theory

The DAB converter consists of two voltage sources on the primary and secondary sides and a transformer with an inductor between the sides. The voltage sources and switch networks form high-frequency AC square waveforms across the inductor.

In the case of a full-bridge switching network, the AC square voltage generator can form +VDC, 0, and –VDC voltage. In the case of a half-bridge switching network, the AC voltage generator can form only +VAC/2 and –VAC/2 voltage. In case of this reference design, the DC side has full-bridge and AC side has half-bridge configuration.

Note: From this point in the document to the end of the document, the DC side is called primary and the AC side is called the secondary side.

Each leg in the bridges has a 50% duty cycle and the power flow is controlled by changing the phase shift between legs. The phase shift between primary side leg is called internal phase shift. This phase shift determines the width of the voltage pulse applied to the inductor from the primary side. The secondary side does not have internal phase shift ability due to the half-bridge nature. Nevertheless, the controller has the ability to control the phase shift between centers of the primary and secondary side voltage pulses. This phase shift is commonly called external, or fundamental phase shift. The power transfer has much higher sensitivity to the external phase shift, so power transfer is commonly used for the output power regulation. The internal phase shift is commonly used for optimization purposes to decrease RMS current and extend ZVS range.