A power supply comprising: a three-phase AC power source; a first diode bridge comprised of six diodes which are connected to the three-phase AC power source via reactors (2, 3, 4); a second diode bridge comprised of six diodes, having a positive-polarity output terminal (P OUT 6) commonly connected to a positive-polarity output terminal (P OUT 5) of the first diode bridge; characterised in that the power supply further comprises: a third diode bridge comprised of six diodes, having a negative-polarity output terminal (N OUT 7) commonly connected to a negative-polarity output terminal (N OUT 5) of the first diode bridge and having a positive-polarity output terminal (P OUT 7) connected to a negative-polarity output terminal (N OUT 6) of the second diode bridge; and total six capacitors (8, 10, 12; 9, 11, 13), with three capacitors (8, 10, 12) thereof being connected between AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u2, v2, w2) of the second diode bridge respectively with one capacitor per phase, and with the remaining three capacitors (9, 11, 13) thereof being connected between the AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u3, v3, w3) of the third diode bridge respectively with one capacitor per phase. a three-phase AC power source; a first diode bridge comprised of six diodes which are connected to the three-phase AC power source via reactors (2, 3, 4); a second diode bridge comprised of six diodes, having a positive-polarity output terminal (P OUT 6) commonly connected to a positive-polarity output terminal (P OUT 5) of the first diode bridge; characterised in that the power supply further comprises: a third diode bridge comprised of six diodes, having a negative-polarity output terminal (N OUT 7) commonly connected to a negative-polarity output terminal (N OUT 5) of the first diode bridge and having a positive-polarity output terminal (P OUT 7) connected to a negative-polarity output terminal (N OUT 6) of the second diode bridge; and total six capacitors (8, 10, 12; 9, 11, 13), with three capacitors (8, 10, 12) thereof being connected between AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u2, v2, w2) of the second diode bridge respectively with one capacitor per phase, and with the remaining three capacitors (9, 11, 13) thereof being connected between the AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u3, v3, w3) of the third diode bridge respectively with one capacitor per phase. a third diode bridge comprised of six diodes, having a negative-polarity output terminal (N OUT 7) commonly connected to a negative-polarity output terminal (N OUT 5) of the first diode bridge and having a positive-polarity output terminal (P OUT 7) connected to a negative-polarity output terminal (N OUT 6) of the second diode bridge; and total six capacitors (8, 10, 12; 9, 11, 13), with three capacitors (8, 10, 12) thereof being connected between AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u2, v2, w2) of the second diode bridge respectively with one capacitor per phase, and with the remaining three capacitors (9, 11, 13) thereof being connected between the AC input terminals (u1, v1, w1) of the first diode bridge and AC input terminals (u3, v3, w3) of the third diode bridge respectively with one capacitor per phase.