TIDUFC8 July   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Introduction
      2. 2.2.2 Basic Operation Principles and ZVS Requirements
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC27288
      2. 2.3.2 UCC23513
      3. 2.3.3 TMS320F2800137
      4. 2.3.4 TLV9062
      5. 2.3.5 INA181
      6. 2.3.6 TPSM861252
      7. 2.3.7 AMC0311R
  9. 3System Design Theory
    1. 3.1 Design Theory
      1. 3.1.1 Resonant Tank Design
      2. 3.1.2 Full-Range ZVS Realization
      3. 3.1.3 Total Control Algorithm
      4. 3.1.4 Resonant Tank RMS Current Analysis
    2. 3.2 Hardware Design Theory
      1. 3.2.1 Resonant Capacitors
      2. 3.2.2 Power Stage
      3. 3.2.3 Voltage Sensing
      4. 3.2.4 Current Sensing
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
      1. 4.2.1 Simulation
    3. 4.3 Test Setup
    4. 4.4 Test Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Layout Prints
    2. 5.2 Tools
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

1 System Description

Energy storage system (ESS) play an important role in renewable energy applications. Depending on the system voltage, capacity and usage, ESS can be divided into three different categories: residential ESS, commercial and industrial ESS, and grid ESS. Commercial and industrial, and grid ESS contain several racks that each contain packs in stack. Residential ESS only contains packs. Residential ESS is divided into high-voltage residential ESS and low-voltage residential ESS. Among them, the high-voltage system is composed of packs connected in series with each other to form high voltage, and then inverted to the grid through PCS (bidirectional DC/DC + bidirectional DC/AC). Figure 1-1 shows the system architecture for a high-voltage residential ESS.


TIDA-010966 Architecture of High-Voltage Residential ESS

Figure 1-1 Architecture of High-Voltage Residential ESS

Battery packs connected in series produce identical charge and discharge current profiles. Pack voltage imbalances result from degree of aging differences between packs. Inconsistent voltage levels affect system utilization and lifespan. Weaker packs develop higher voltages under same charging energy, further exacerbating imbalance.

There are several reasons why the aging degree of a pack is not the same:

  • With the increase of the service life of the energy storage system, the heat of different packs is different, which gradually causes inconsistencies between packs.
  • There is a mix of old and new packs in residential ESS which causes capacity inconsistencies between packs.

Therefore, to optimize the imbalance between packs, active pack balance is required to balance the voltages between different packs, Figure 1-2 shows several bidirectional isolated DC/DC converters are used here as active pack balance.

These bidirectional DC/DC converters are terminated with a battery pack on one end and an auxiliary power rail on the board on the other.

When high-voltage conditions prevail, discharge the pack directly from the battery connector. Conversely, recharge the pack when low-voltage conditions exist. Using this approach maintains voltage balance between packs.


TIDA-010966 Active Pack Balance in High-Voltage Residential ESS

Figure 1-2 Active Pack Balance in High-Voltage Residential ESS

Power density, system cost, and system efficiency are important requirements of a converter used in this system. A bidirectional isolated dual-bridge series resonant DC/DC converter only has two half bridges that can achieve isolated bidirectional power transmission. Less switches can help improve power density and system cost. This topology also can help release Zero Voltage Switching (ZVS), which also can help improve system efficiency.

This reference design proposes a brand-new architecture for active pack balance in residential ESS, and uses bidirectional isolated dual-bridge series resonant DC/DC converter to achieve power transmission. For this topology, this reference design proposes new varying frequency plus phase-shift control methods to provide full-range ZVS.