Development On Half-bridge LLC Resonant DC/DC Converter

With the development of science and technology and the improvement of human life, auto industry has been rapid development, and increasingly high levels of electronic, digital and intelligent in vehicle control system, air conditioning, sound and other vehicle electronic equipment becomes richer and more complex, The corresponding vehicle power systems have become increasingly demanding, especially the rise of environmental protection energy-saving vehicles, such as electric vehicles, electric buses, so the car DC power system requires increasing the capacity and performance. Relative to gasoline generator vehicles, electric vehicles is generally equipped with DC/DC converter, it converters the high voltage DC battery power (typically 280V-360V) to low voltage to power the vehicle electronic system. Due to special application environment of on-board DC/DC converter, requested its small size, high power, high efficiency and high characteristics of earthquake-resistant.Traditional PWM DC/DC converter is a hardware switch, produces a large amount of loss in switch's turn-on and turn-off, has low conversion efficiency.In order to achieve high efficiency,the DC/DC converter of electric vehicles must achieve soft-switching technique.Half-bridge LLC resonant converter soft-switching technology can achieve ZVS of the primary switches in the condition or wide input and full load, easy to realize ZCS of secondary rectifier diodes and has low witching loss, high conversion efficiency,applies to the DC/DC converter of electric vehicles.In this paper, Half-bridge LLC resonant converter is analyzed in detail and used in the electric vehicles dedicated DC/DC converter. In this thesis, a variety of traditional resonant converters is described, and the working process of Half-bridge LLC resonant converter is introduced.Based on the FHA (First Harmonic Approximation),the steady-state model of Half-bridge LLC resonant converter is given, a method on designing the parameters of Half-bridge LLC resonant converter is proposed, finally the method is checked by saber simulation. In order to achieve transmission of information between DC/DC converter and the electric vehicle control unit, so DSP is selected as the control IC in the paper, Designed based on TMS320F28033,the DSP implementation of an incremental digital PID control algorithm and system software architecture is given.Finally,the converter experimental platform is build, the experimental waveforms and data analysis prove the correctness of the theoretical analysis and reasonable of design method.