A three-level converter includes at least one phase bridge arm, each including an upper-half and a lower-half bridge arm circuit modules. The upper-half bridge arm circuit module includes a first and a second switch units that are in series connection, and a first diode unit. The lower-half bridge arm circuit module includes a third and a fourth switch units that are in series connection, and a second diode unit. The first and second diode units are connected to the neutral point of the capacitor unit; the second and third switch units are connected to the alternating-current terminal; The first and the fourth switch unit is respectively connected to the positive terminal and negative terminal of the direct-current bus; the capacitor unit is connected to the direct-current bus between the positive and negative terminals. The two modules are disposed side by side and facing each other.