Three-phase four-wire active load with performance of energy regeneration

In this paper, a three-phase four-wire active load capable of energy regeneration is proposed. The proposed active load comprises a load characteristic power converter, an energy regeneration power converter and a DC capacitor. The load characteristic power converter and the energy regeneration power converter are connected in series, and the DC capacitor acting as the energy buffer is located at the common dc bus of both power converters. The load characteristic power converter can be used to simulate a resistive load, a resistive/inductive load, a resistive/capacitive load and a rectifier load. The energy consumed by the load characteristic power converter will be regenerated back to the utility through the energy regeneration power converter. Moreover, the energy regeneration power converter also serves as an active power filter (APF) to suppress the harmonic current and compensate for the reactive power of the tested equipment. Hence, the utility supplies only a small real power to overcome the power loss of the active load and tested equipment. A prototype is developed and tested to verify the performance of the proposed active load. Experimental results show that the proposed active load can efficiently perform the expected function.