Research On Implementation Of The TCM Model In Bi-directional Buck/Boost Converter Without Currency Zero Crossing Detection

The bidirectional buck/boost converter is widely used in the new energy systems, electric vehicles and conventional drive power. However, this type converter is not easy to achieve soft switching, which case the contradictions between power density and the efficiency. And, it will also restrict the further development of this type of converter.Triangle Current Mode(TCM) control get buck/boost converter all switch achieved soft switch, Which improve the efficiency of this type converter. However the traditional TCM model based on control the time of each process, which requires a current zero-crossing detection, and control is very complex, which is not convenience to achieve the multi-module Interleaved. This paper proposes a control scheme base on the frequency control scheme to achieve TCM simplify the traditional control scheme, while makes multi-module interleaved easier to implement.Firstly, the relevant principles of the process and the implementation process of TCM patterns are analyzed to get the necessary condition to achieve soft-switching. Then, the characteristics of frequency and dead time of TCM patterns are analyzed to get the formula of critical dead time and critical frequency. Based on the formulas a strategy the based on the frequency control scheme to achieve TCM is proposed. The strategy does not need the zero-crossing detection and is more compact than traditional solutions. At the same time, a new master-slave control scheme make the multi-module Interleave much easier. After this, I design the main parameter of the main circuit and analysis the loss of various parts.To verify the correctness of the proposed scheme, a 500 w bidirectional buck/boost converter composed by three modules is set up in the laboratory. and buck, boost modes and interleaved mode experiment have been done to test the feasibility of the scheme.