具有短路限流能力的大变比DC/DC变换器

A large-step-ratio DC/DC converter with the abilities of automatic current-limiting and bidirectional power flow is proposed. It is suitable to be used as an interface circuit between high voltage direct current (HVDC) and low voltage direct current (LVDC) transmission lines. The DC/DC converter works with three-level voltage. By adjusting its duty ratio and phase shift, the transmission power of the converter can be changed, while the bidirectional power flow can be realized. The circuit operates with a trapezoidal current wave, and realizes partial soft switching with a high efficiency. When a short-circuit fault occurs the DC/DC converter can automatically limit the current, whose peak current value through the switch is same as that in normal operation. Based on these features, a converter is designed and validated by simulation, whose input voltage is 12 kV, output voltage is 1 kV, and transmission power is 100 kW.