Implementation of a loss-free programmable AC load

The burn-in and operation tests of power converters, UPSs and other kinds of power supplies are carried out using resistors combined with reactive elements as load, which have losses of energy. Several solutions have been proposed using switching power converters as DC load, with the purpose of saving energy during these reliability tests. The implementation of a loss-free programmable AC load is presented, which can be programmed with arbitrary current waveforms and work in the four quadrants of the I-V characteristic. The topology of switching current inverter, implemented with IGBTs as switching devices, was used. This kind of solution can be used as an emulator of the actual loads during the burn-in test and operation tests of the circuits with voltage source behaviour. The energy demanded from the circuit under test can be recycled to the utility.