Study On A New Bi-directional Three-level DC/DC Converter

With the development of power electronics technology, bi-directional DC/DC converters is applied more and more widely in the areas of electric vehicles, automotive electronics, communication power and aerospace, energy storage systems, and so on, which require bi-directional DC/DC converters to handle higher voltage and current level. While as the current equality of the switch, if applied to large-capacity high-pressure situations, traditional two-level converter is difficult to meet its processing requirements, so topology is a useful way to enhance property, extend applied area and enhance processing ability for voltage and current. For applying to large-capacity high-pressure situations, multi-level technology is introduced to bi-directional DC/DC converters to reduce the voltage level.After learning of a variety of multi-level bi-directional DC/DC converters home and abroad, this paper investigated a topology based on the basic half-bridge module, and expanding a series of topology, which include cascaded bi-directional DC/DC converter topology, multi-phase bi- directional DC/DC converter topology, combined multi-level bi- directional DC/DC converter topology and complex multi-level bi- directional DC/DC converter topology, and so on. And then this paper analyzes the operation principle of the complex three-level bi- directional DC/DC converter topology, which shows that this topology can not only reduce the tolerance of switch voltage level but also achieve the continuous voltage change and a large ratio without transformer.In order to verify the correction of this topology a three-level bi-directional DC/DC converter simulation model is built and completed the simulation experiments. In the open-loop control mode, affection parameter on the converters is analyzed and output characteristic under different duty ratio is observed. In the closed-loop control mode, output characteristic is observed in the situation of different input voltage, given voltage disturbance and input voltage disturbance. Simulation results show that this converter can not only achieve large ratio continuous changes but also can reduce the tolerance of switch voltage level, which providing strong protection for its application in high voltage.Finally, a test prototype is designed, including the main circuit, drive circuit, control circuit and detection circuit. By writing and debugging control program, the PWM control signal is output to drive the main circuit on the DSP 2812, and get part of the PWM test waveform.