TIDUES0E June   2019  – April 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1  UCC21710
      2. 2.2.2  UCC14141-Q1
      3. 2.2.3  AMC1311
      4. 2.2.4  AMC1302
      5. 2.2.5  OPA320
      6. 2.2.6  AMC1306M05
      7. 2.2.7  AMC1336
      8. 2.2.8  TMCS1133
      9. 2.2.9  TMS320F280039C
      10. 2.2.10 TLVM13620
      11. 2.2.11 ISOW1044
      12. 2.2.12 TPS2640
    3. 2.3 System Design Theory
      1. 2.3.1 Dual Active Bridge Analogy With Power Systems
      2. 2.3.2 Dual-Active Bridge – Switching Sequence
      3. 2.3.3 Dual-Active Bridge – Zero Voltage Switching (ZVS)
      4. 2.3.4 Dual-Active Bridge - Design Considerations
        1. 2.3.4.1 Leakage Inductor
        2. 2.3.4.2 Soft Switching Range
        3. 2.3.4.3 Effect of Inductance on Current
        4. 2.3.4.4 Phase Shift
        5. 2.3.4.5 Capacitor Selection
          1. 2.3.4.5.1 DC-Blocking Capacitors
        6. 2.3.4.6 Switching Frequency
        7. 2.3.4.7 Transformer Selection
        8. 2.3.4.8 SiC MOSFET Selection
      5. 2.3.5 Loss Analysis
        1. 2.3.5.1 SiC MOSFET and Diode Losses
        2. 2.3.5.2 Transformer Losses
        3. 2.3.5.3 Inductor Losses
        4. 2.3.5.4 Gate Driver Losses
        5. 2.3.5.5 Efficiency
        6. 2.3.5.6 Thermal Considerations
  9. 3Circuit Description
    1. 3.1 Power Stage
    2. 3.2 DC Voltage Sensing
      1. 3.2.1 Primary DC Voltage Sensing
      2. 3.2.2 Secondary DC Voltage Sensing
        1. 3.2.2.1 Secondary Side Battery Voltage Sensing
    3. 3.3 Current Sensing
    4. 3.4 Power Architecture
      1. 3.4.1 Auxiliary Power Supply
      2. 3.4.2 Gate Driver Bias Power Supply
      3. 3.4.3 Isolated Power Supply for Sense Circuits
    5. 3.5 Gate Driver Circuit
    6. 3.6 Additional Circuitry
    7. 3.7 Simulation
      1. 3.7.1 Setup
      2. 3.7.2 Running Simulations
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Required Hardware and Software
      1. 4.1.1 Hardware
      2. 4.1.2 Software
        1. 4.1.2.1 Getting Started With Software
        2. 4.1.2.2 Pin Configuration
        3. 4.1.2.3 PWM Configuration
        4. 4.1.2.4 High-Resolution Phase Shift Configuration
        5. 4.1.2.5 ADC Configuration
        6. 4.1.2.6 ISR Structure
    2. 4.2 Test Setup
    3. 4.3 PowerSUITE GUI
    4. 4.4 LABs
      1. 4.4.1 Lab 1
      2. 4.4.2 Lab 2
      3. 4.4.3 Lab 3
      4. 4.4.4 Lab 4
      5. 4.4.5 Lab 5
      6. 4.4.6 Lab 6
      7. 4.4.7 Lab 7
    5. 4.5 Test Results
      1. 4.5.1 Closed-Loop Performance
  11. 5Design Files
    1. 5.1 Schematics
    2. 5.2 Bill of Materials
    3. 5.3 Altium Project
    4. 5.4 Gerber Files
    5. 5.5 Assembly Drawings
  12. 6Related Documentation
    1. 6.1 Trademarks
  13. 7Terminology
  14. 8About the Author
  15. 9Revision History

2.3.3 Dual-Active Bridge – Zero Voltage Switching (ZVS)

Between turn-off of one MOSFET and turn-on of the other MOSFET of a branch there is dead time. During this dead time the energy stored in the inductor discharges the output capacitances of the MOSFETs and holds them close to zero voltage before they are turned on. This phenomenon, where the voltage across the MOSFET is close to zero at turn on, is referred to as zero voltage switching (ZVS). This is a major advantage with this topology, where due to the natural lagging current in one of the bridges, the inductive stored energy causes ZVS of all of the lagging bridge switches and some of the switches of the leading bridge. This depends on the stored inductive energy (EL = 0.5LI2) available to charge and discharge the output capacitances of MOSFETs (EC = 0.5CV2), which again depends on the load of the converter and the input to output voltage ratio. A more detailed look on the boundaries of ZVS is documented in Section 2.3.4.2. Here the principal of ZVS is explained with the transition from interval one to interval two. Similar analysis can be done for all turn-on events.

When transition happens from interval one to two, the primary side switches Q1 and Q5 continue conduction, whereas in the secondary, Q6 and Q7 turn off and Q5 and Q8 turn on. Initially the voltage across Q6 and Q7 is zero when conducting, and Q5 and Q8 block the entire secondary voltage. During dead time, when all of the switches in the secondary are off, the inductor-stored energy circulates current which discharges the capacitor across MOSFETs Q5 and Q8 to zero and charges the capacitor across MOSFETs Q6 and Q7 to the full secondary voltage. The current commutation is shown in Figure 2-11.

TIDA-010054 ZVS Transition in Secondary Side - CapacitorFigure 2-11 ZVS Transition in Secondary Side - Capacitor

Once the capacitors have been charged and discharged, the current must continue to flow. The current flows through the diodes D5 and D8, thereby clamping the voltage across MOSFETs Q5 and Q8 to zero as shown in Figure 2-12. During the next interval, MOSFETs Q5 and Q8 are turned on at zero voltage, thereby reducing turn on losses completely. The arrow close to the diode indicates that the diode is conducting and the MOSFET is off.

TIDA-010054 ZVS Transition in Secondary Side - DiodeFigure 2-12 ZVS Transition in Secondary Side - Diode

Similarly, zero voltage switching across the switches of the primary during the transition from interval 2 to 3 is explained in the following section. When transition happens from interval two to three, the secondary side switches Q5 and Q8 continue conduction, whereas in the primary, Q1 and Q4 turn off and Q2 and Q3 turn on. Initially, the voltage across Q1 and Q4 is zero when conducting, and Q2 and Q3 block the entire secondary voltage. During dead time when all of the switches in the primary are off, the inductor stored energy circulates current, which discharges the capacitor across MOSFETs Q2 and Q3 to zero and charges the capacitor across MOSFETs Q1 and Q4 to the full primary voltage. The current commutation is shown in Figure 2-13.

TIDA-010054 ZVS Transition in Primary Side - CapacitorFigure 2-13 ZVS Transition in Primary Side - Capacitor

Once the capacitors have been charged and discharged, the current must continue to flow. The current flows through diodes D2 and D3, thereby clamping the voltage across MOSFETs Q2 and Q3 to zero as shown in Figure 2-14. During the next interval, MOSFETs Q2 and Q3 are turned on at zero voltage, thereby reducing turn on losses completely. The arrow close to the diode indicates that the diode is conducting and the MOSFET is off.

TIDA-010054 ZVS Transition in Primary Side - DiodeFigure 2-14 ZVS Transition in Primary Side - Diode