一种适用于负载功率宽范围变化的直流电流源输入/电压源输出变换器

This article proposed a current-source input and voltage-source output converter for wide range variation of load power. The challenge of constant-current (CC) conversion is the input voltage tends to diverge to the highest at reduced load condition and tends to the lowest at increased load conditions, as the current cannot be varied abruptly. The proposed converter features regulated input characteristics and output voltage from rated power to no load, provides a current-freewheel branch composed of MOSFET and transformer for the constant input current, which solves the problem of input voltage disperse to the highest; besides, the energy stored in the floating capacitor is used as transient energy for the load power increase, which avoids the input voltage disperse to 0 V as it changes from no load to full load, and the energy of the floating capacitor is derived from the transformer magnetic reset. Furthermore, the typically CC supply systems operate at low currents and the power is limited by the input voltage, so the proposed converter employs two capacitors charging in series and discharging interleaved, which improved the input voltage level and reduced the output filter inductance. Moreover, the lagged freewheel switches realize zero-voltage turn-on, which is helpful for efficiency. A prototype with 2-A dc input and 250-V/530-W output is built to verify the feasibility of the proposed topology.