TIDUF87 November   2024

 

  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 Design Considerations
      1. 2.2.1 Current and Voltage Controller
      2. 2.2.2 DC/DC Start-Up
      3. 2.2.3 High-Resolution PWM Generation
    3. 2.3 Highlighted Products
      1. 2.3.1 TMS320F28P650DK
      2. 2.3.2 ADS8588S
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Software Requirements
      1. 3.2.1 Opening the Project Inside Code Composer Studio
      2. 3.2.2 Project Structure
      3. 3.2.3 Software Flow Diagram
    3. 3.3 Test Setup
      1. 3.3.1 Hardware Setup to Tune the Current and Voltage Loop
      2. 3.3.2 Hardware Setup to Test Bidirectional Power Flow
      3. 3.3.3 Hardware Setup for Current and Voltage Calibration
    4. 3.4 Test Procedure
      1. 3.4.1 Lab Variables Definitions
      2. 3.4.2 Lab 1. Open-Loop Current Control Single Phase
        1. 3.4.2.1 Setting Software Options for Lab 1
        2. 3.4.2.2 Building and Loading the Project and Setting up Debug Environment
        3. 3.4.2.3 Running the Code
      3. 3.4.3 Lab 2. Closed Loop Current Control Single Phase
        1. 3.4.3.1 Setting Software Options for Lab 2
        2. 3.4.3.2 Building and Loading the Project and Setting up Debug Environment
        3. 3.4.3.3 Running the Code
      4. 3.4.4 Lab 3. Open Loop Voltage Control Single Channel
        1. 3.4.4.1 Setting Software Options for Lab 3
        2. 3.4.4.2 Building and Loading the Project and Setting up Debug Environment
        3. 3.4.4.3 Running the Code
      5. 3.4.5 Lab 4. Closed Loop Current and Voltage Control Single Channel
        1. 3.4.5.1 Setting Software Options for Lab 4
        2. 3.4.5.2 Building and Loading the Project and Setting up Debug Environment
        3. 3.4.5.3 Running the Code
      6. 3.4.6 Lab 5. Closed Loop Current and Voltage Control Four Channels
        1. 3.4.6.1 Setting Software Options for Lab 5
        2. 3.4.6.2 Building and Loading the Project and Setting up Debug Environment
        3. 3.4.6.3 Running the Code
      7. 3.4.7 Calibration
    5. 3.5 Test Results
      1. 3.5.1 Current Loop Load Regulation
      2. 3.5.2 Current Loop Linearity Test
      3. 3.5.3 Voltage Loop Linearity Test
      4. 3.5.4 DCM Start-Up
      5. 3.5.5 Bidirectional Current Switching Time
      6. 3.5.6 Thermal Performance
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author

2.2.2 DC/DC Start-Up

A bidirectional power stage is used to charge and discharge batteries. In a normal start-up condition, buck converter output increases from 0V to the target voltage. If a battery load is connected while buck is ramping from 0V, this can result in large current overshoot. This problem can be avoided in two ways. The first method is starting the buck converter with output relay open, and setting the relay to closed position when buck converter reaches close to the battery voltage, as shown in the Figure 2-3. The second method is starting the buck converter in DCM mode with the low-side switch OFF during charging, or with the high-side OFF during discharging, as shown in Figure 2-4. A timer is required to switch from non-synchronous mode to synchronous mode.

TIDA-010090 Synchronous Start-Up Figure 2-3 Synchronous Start-Up
TIDA-010090 Nonsynchronous Start-Up Figure 2-4 Nonsynchronous Start-Up