Power conversion apparatus

摘要

When a snubber capacitor is charged to a level greater than or equal to a predetermined voltage, a protection circuit renders a clamp diode conductive to complete charging of the snubber capacitor.

主权项

1. A power conversion apparatus converting DC power supplied from a DC power supply having a first electrode and a second electrode into AC power for supply to a load, said power conversion apparatus comprising:
an AC terminal for outputting said AC power, a first DC division capacitor and a second DC division capacitor connected in series between said first electrode and said second electrode, a first main switch having a first end coupled to said first electrode of said DC power supply, and a second end coupled to said load, a first main diode connected in parallel with said first main switch, so as to have a conducting direction opposite to the conducting direction of said first main switch, a second main switch having a first end coupled to a second end of said first main switch, and a second end coupled to said second electrode of said DC power supply, and provided so as to have a conducting direction identical to the conducting direction of said first main switch, a second main diode connected in parallel with said second main switch, so as to have a conducting direction opposite to the conducting direction of said second main switch, a first snubber capacitor and a second snubber capacitor, a first snubber diode and a second snubber diode connected in series between said first snubber capacitor and said second snubber capacitor, a protection circuit for causing, when voltage applied to said first snubber capacitor becomes greater than or equal to a predetermined value or when voltage applied to said second snubber capacitor becomes greater than or equal to a predetermined value, a charging current formerly flowing from said DC power supply to said first snubber capacitor or said second snubber capacitor to flow to another current path, and a control circuit controlling said first main switch and said second main switch to be turned on and off, said first snubber capacitor provided between an anode of said first main diode and a cathode of said first snubber diode, said second snubber capacitor provided between a cathode of said second main diode and an anode of said second snubber diode, said protection circuit including a transformer, and a first clamp diode and a second clamp diode connected in parallel with said first main switch and said second main switch, and provided between said first electrode and said second electrode, so as to have a conducting direction opposite to the conducting direction of said first main switch and said second main switch,
said transformer including
a first primary winding and a second primary winding connected in series, anda first secondary winding and a second secondary winding provided corresponding to said first and second primary windings, respectively, a connection node of said first primary winding and said second primary winding being connected to said AC terminal, and a coupling node of a first unit having said first clamp diode and said first secondary winding connected in series and a second unit having said second clamp diode and said second secondary winding connected in series being connected to a connection node of said first DC division capacitor and said second DC division capacitor.