Abstract
In the DC distribution system, to step down the DC voltage level from the AC grid voltage, the conventional topologies require multiple power conversion stages and bulky line-frequency transformers, which degrade their power density and cost-effectiveness. In addition, the conventional topologies suffer from a shoot-through problem resulting in their low system reliability. In this paper, to overcome the above issues, systematic design approaches of a three-phase buck rectifier with an uninterruptible power supply (UPS) and a protection algorithm are proposed to obtain the high reliability of the DC distribution system, which can deal with fault conditions and can regulate the output voltage level. It only requires a single stage of the three-phase buck rectifier. Also, a thyristor switch is added without any commutation circuits to cut off the output from the fault circuit. The shoot-through faults do not occur in the buck rectifier, leading to high reliability. A dual-active-bridge (DAB) DC-DC converter is applied as the UPS to supply the electric power from the battery when the buck rectifier is shut down under the fault conditions. Finally, the protection algorithm is proposed to detect the fault conditions and to regulate the output voltage level.
Highlights
Nowadays, DC distribution systems are replacing conventional AC systems due to their outstanding features [1,2,3]
Since the conventional boost-type AC-DC rectifiers are based on topologies, the shoot-through fault occurs when one or one more are broken in a short-circuit bridge topologies, the shoot-through fault occurs when orswitches more switches are broken in a shortmanner
Even if the buck rectifier has more diodes than the conventional AC-DC rectifier to cause component failures, it is more robust against failures than the conventional system
Summary
DC distribution systems are replacing conventional AC systems due to their outstanding features [1,2,3]. Since the conventional boost-type AC-DC rectifiers are based on topologies, the shoot-through fault occurs when one or one more are broken in a short-circuit bridge topologies, the shoot-through fault occurs when orswitches more switches are broken in a shortmanner It makes the DC-link voltage to zero resulting in a shut-down of the entire system. TheThe three-phase buck rectifier can can directly step step down the DC-link voltage from fromAC thegrid, AC grid, which reduce additional components powerconversion conversionstages stagesin in the the entire entire the which can can reduce additional components or or power system This this topology topology does does not not have have the the shoot-through shoot-through problem problem in in aa switch switch fault fault case. Detect the fault condition and to regulate the output voltage, a protection algorithm is developed
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