A three-phase converter, configured to be connected between a direct current system and an alternating current system to perform interconversion between a direct current and an alternating current, wherein the three-phase converter comprises a switching network that is configured to convert a direct current into multiple levels, a three-phase filter that is connected to the switching network and that outputs three-phase currents i a, i b, and i c based on the multiple levels, a sampling unit connected to the three-phase filter, a control unit (20, 204) connected to the sampling unit, an active damping unit connected to both the control unit (20, 204) and the sampling unit, and a modulation unit connected between the active damping unit and the switching network, wherein the sampling unit is configured to: obtain the three-phase currents i a, i b, and i c that are output by the three-phase filter, and send the three-phase currents i a, i b, and i c to the active damping unit; the active damping unit is configured to: perform independent regulation on the three-phase currents i a, i b, and i c respectively by using mutually independent regulation functions to obtain regulation components v'a, v'b, and v'c that are in a one-to-one correspondence with the three-phase currents i a, i b, and i c, obtain a zero-sequence regulation component vo according to the regulation components υ' a, υ' b, and υ ' c, separately superpose the zero-sequence regulation component υ o with three-phase modulated waves v a, v b, and v c that are output by the control unit (20, 204) to obtain new three-phase modulated waves υ a_mod, υ b_mod, and υ c_mod, and transmit the new three-phase modulated waves υ a_mod, υ b_mod, and υ c_mod to the modulation unit; the modulation unit is configured to modulate the new three-phase modulated waves υ a_mod, υ b_mod, and υ c_mod into drive signals of the switching network, to drive the switching network to output the multiple levels to the three-phase filter; and the three-phase filter is configured to convert the multiple levels into an alternating current that is input to the alternating current system, wherein the active damping unit comprises a current regulator G a, a current regulator G b, and a current regulator G c; and the current regulator G a, the current regulator G b, and the current regulator G c respectively receive the three-phase currents i a, i b, and i c in a one-to-one correspondence, and regulate the three-phase currents i a, i b, and i c respectively by using the mutually independent regulation functions, to obtain the regulation components υ' a, υ' b, and υ ' c that are in a one-to-one correspondence with the three-phase currents i a, i b, and i c,; and characterized in that the active damping unit further comprises a zero-sequence regulation component calculator; and the zero-sequence regulation component calculator receives the regulation components υ' a, υ' b, and υ ' c that are respectively output by the current regulator G a, the current regulator G b, and the current regulator G c, and calculates an average or a weighted average of the regulation components υ' a, υ' b, and υ ' c, wherein a result of the average or the weighted average is the zero-sequence regulation component υ o.