Abstract：When the Vienna rectifier is connected to unbalanced loads operating under light load conditions，

the slight power difference causes unbalanced voltage of bipolar DC bus，which increases the voltage stress on the

switching device and DC-link capacitance. To solve the above problems，a DC offset reduction of neutral point

voltage strategy based on reactive current compensation for Vienna rectifier with bipolar DC-link was proposed. By

combining the amplitude of zero-sequence component，which is superimposed onto the three-phase reference

voltage，the neutral point current for various power conditions can be obtained. The effect of the phase angle

difference between the reference voltage and the input current on the neutral point current was analyzed，and the

maximum reactive currents of the odd and even sectors was obtained according to the operating region of the

Vienna rectifier. In order to increase the neutral point current under light load condition，the reactive current was

injected to change the phase angle difference according to the contour of neutral point current，thereby achieving

the balance of bipolar DC bus under light load conditions. Finally，the effectiveness of the proposed strategy was

verified on the Vienna rectifier experimental platform.

      Key words：Vienna rectifier；balance of DC-link voltage；light load；bipolar DC-link voltage；compensation of

reactive current