A converter (120, 300), configured to be connected between a direct current system and an alternating current system for mutual conversion between a direct current and an alternating current, wherein the converter (120, 300) comprises a switching network, a filter, and a control unit, the switching network comprises a first switching circuit and a second switching circuit, the control unit is configured to output a control signal to the switching network, the switching network is configured to convert, into multiple-levels voltage according to the control signal that is output by the control unit, a direct current that is output by the direct current system, and the filter is configured to output an alternating current to the alternating current system according to the multiple levels; the first switching circuit comprises M energy storage elements and M bridge arm circuits, one of the M bridge arm circuits comprises only one full-controlled component, remaining M-1 bridge arm circuits each comprise two full-controlled components that are reversely connected in series, and M is an integer greater than or equal to 1; a first end of an i th bridge arm circuit in the M bridge arm circuits is connected to a first end of an (i+1) th bridge arm circuit in the M bridge arm circuits by using an i th energy storage element in the M energy storage elements, a first end of an M th bridge arm circuit in the M bridge arm circuits is connected to a first end of the filter by using an M th energy storage element in the M energy storage elements, a second end of each of the M bridge arm circuits is connected to a second end of the filter, and i is an integer that is greater than or equal to 1 and less than M+1; the second switching circuit comprises N energy storage elements and N bridge arm circuits, one of the N bridge arm circuits comprises only one full-controlled component, remaining N-1 bridge arm circuits each comprise two full-controlled components that are reversely connected in series, and N is an integer greater than or equal to 4-M; a first end of a j th bridge arm circuit in the N bridge arm circuits is connected to a first end of a (j +1) th bridge arm circuit in the N bridge arm circuits by using a j th energy storage element in the N energy storage elements, a first end of an N th bridge arm circuit in the N bridge arm circuits is connected to the first end of the filter by using an N th energy storage element in the N energy storage elements, a second end of each of the N bridge arm circuits is connected to the second end of the filter, and j is an integer that is greater than or equal to 1 and less than N+1; and each full-controlled component in the N bridge arm circuits and the M bridge arm circuits is connected to the control unit, and the control unit is specifically configured to control turning-on and turning-off of each full-controlled component, wherein the first switching circuit and the second switching circuit comprise different numbers of bridge arm circuits, and wherein each full-controlled component is a switching transistor. the first switching circuit comprises M energy storage elements and M bridge arm circuits, one of the M bridge arm circuits comprises only one full-controlled component, remaining M-1 bridge arm circuits each comprise two full-controlled components that are reversely connected in series, and M is an integer greater than or equal to 1; a first end of an i th bridge arm circuit in the M bridge arm circuits is connected to a first end of an (i+1) th bridge arm circuit in the M bridge arm circuits by using an i th energy storage element in the M energy storage elements, a first end of an M th bridge arm circuit in the M bridge arm circuits is connected to a first end of the filter by using an M th energy storage element in the M energy storage elements, a second end of each of the M bridge arm circuits is connected to a second end of the filter, and i is an integer that is greater than or equal to 1 and less than M+1; the second switching circuit comprises N energy storage elements and N bridge arm circuits, one of the N bridge arm circuits comprises only one full-controlled component, remaining N-1 bridge arm circuits each comprise two full-controlled components that are reversely connected in series, and N is an integer greater than or equal to 4-M; a first end of a j th bridge arm circuit in the N bridge arm circuits is connected to a first end of a (j +1) th bridge arm circuit in the N bridge arm circuits by using a j th energy storage element in the N energy storage elements, a first end of an N th bridge arm circuit in the N bridge arm circuits is connected to the first end of the filter by using an N th energy storage element in the N energy storage elements, a second end of each of the N bridge arm circuits is connected to the second end of the filter, and j is an integer that is greater than or equal to 1 and less than N+1; and each full-controlled component in the N bridge arm circuits and the M bridge arm circuits is connected to the control unit, and the control unit is specifically configured to control turning-on and turning-off of each full-controlled component, wherein the first switching circuit and the second switching circuit comprise different numbers of bridge arm circuits, and wherein each full-controlled component is a switching transistor.