SPRADJ1A June   2024  – August 2024 TMS320F280021 , TMS320F280023 , TMS320F280023C , TMS320F280025 , TMS320F280025C , TMS320F280033 , TMS320F280034 , TMS320F280037 , TMS320F280037C , TMS320F280039 , TMS320F280039C , TMS320F280041 , TMS320F280041C , TMS320F280045 , TMS320F280049 , TMS320F280049C , TMS320F28075 , TMS320F28076 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28376D , TMS320F28376S , TMS320F28377D , TMS320F28377S , TMS320F28378D , TMS320F28378S , TMS320F28379D , TMS320F28379S , TMS320F28P550SJ , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2HHC LLC Control Architecture and Logic Diagram
    1. 2.1 CMPSS
    2. 2.2 EPWM
    3. 2.3 Configurable Logic Block (CLB)
  6. 3C2000 Configurations in HHC LLC
    1. 3.1 CMPSS Configurations
    2. 3.2 EPWM Configurations
    3. 3.3 CLB Configurations
  7. 4System Control Method
    1. 4.1 Soft Start
    2. 4.2 Burst Mode Control
    3. 4.3 Minimum and Maximum Frequency Clamping
  8. 5Resonant Capacitor Voltage Sensing Design
  9. 6Summary
  10. 7References
  11. 8Revision History

1 Introduction

Voltage mode control has been typically used for LLC resonant converter where the output voltage loop directly controls the switching frequency. However, the compensation design is relatively challenging since the frequency response of the LLC converter with voltage mode control shows very complicated characteristics with multiple poles, and the location of the poles changes with input voltage and load conditions. [1]

With the higher requirement of load transient response requirements in power supply applications, some control methods like HHC (hybrid hysteretic control) or current mode control attract more attention in LLC converters. HHC scheme is proposed to achieve the best-in-class transient performance by overcoming the disadvantage of charge control and avoiding unstable condition by adding in a frequency ramp compensation [2]. It has changed the LLC plant transfer function to an equivalent first order system, characterized by a relatively stable cross frequency and small variation of DC gains, which has made the loop design easy to achieve higher bandwidth with enough phase margin.

Analog controllers, like UCC25640x series, are mature designs with HHC control schemes and widely used in the market. However, how to implement HHC LLC control scheme with digital controller has been requested for a long time from the market, especially for server PSU, which requires digital controllers for more flexible system design. The application report can discuss the design details on HHC LLC scheme with latest F2800x C2000 devices. Additional details can be found in the PMP41081 reference design, and the software of this design is available inside the latest C2000Ware Digital Power SDK.