A series active voltage quality regulator（AVQR） that the DC-link voltage can be adjusted automatically is proposed. With thyristor rectifiers， the implementation of the variable DC-link voltage adapted to the missing voltage of the AVQR improves the regulators efficiency greatly. The strategy is analyzed in detail. Taking a 2 kVA experimental prototype as an example， the losses and efficiency of the diode and thyristor rectifier are compared and analysed. Finally， the validity and effectiveness of the proposed strategy are verified by experimental test. The experimental test results show that the efficiency of the prototype is increased significantly at the same supply voltage and load condition.