Power conversion device
Disclosed is a power conversion device which achieves reductions in switching loss due to a reverse recovery current and heat generation loss. Specifically disclosed is a power conversion device provided with a cascode element configured by electrically connecting a normally-on switching element and a normally-off switching element in series and connecting a gate terminal of the normally-on switching element and a source terminal of the normally-off switching element via a cascode connection diode, and a high-speed diode electrically connected in parallel with the cascode element and having a cathode region connected to a positive electrode terminal and an anode region connected to a negative electrode terminal.
1. A power conversion device comprising:
a DC power source; a plurality of main circuit switching elements constituting a positive arm and a negative arm which are bridge-connected so as to convert DC of the DC power source into AC; high-speed diodes connected in reverse parallel to the plurality of main circuit switching elements, respectively; and gate driving circuits that perform switching of the plurality of main circuit switching elements, respectively, at a desired timing,
the main circuit switching elements constituting the positive and the negative arms each including a normally-on switching element, a normally-off switching element whose positive terminal is connected to the negative terminal of the normally-on switching element, and a cascode-connecting diode series-connected between the gate of the normally-on switching element and the negative terminal of the normally-off switching element in a forward direction, and
each of the gate driving circuit being connected to the gate of the normally-on switching element and the normally-off switching element constituting the main circuit switching element.
2. The power conversion device according to claim 1 , wherein
the gate driving circuit drives the normally-on switching element and the normally-off switching element in an independent manner.
3. The power conversion device according to claim 1 , wherein
withstand voltage of the normally-off switching element is set lower than that of the normally-on switching element.
4. The power conversion device according to claim 1 , wherein
withstand voltage of the cascode-connecting diode is set equal to that of the normally-off switching element.
5. The power conversion device according to claim 1 , wherein
the high-speed diode is a unipolar diode.
6. The power conversion device according to claim 5 , wherein
the unipolar diode is a Schottky Barrier Diode, a Junction Barrier Controlled Schottky Diode, or a Merged PiN Schottky Diode.
7. The power conversion device according to claim 1 , wherein
the normally-on switching element is constituted by a wide-gap semiconductor.
8. The power conversion device according to claim 7 , wherein
the wide-gap semiconductor is SiC (silicon carbide), GaN (gallium nitride), or diamond.
9. The power conversion device according to claim 1 , wherein
the high-speed diode is constituted by a wide-gap semiconductor.
10. The power conversion device according to claim 9 , wherein
the wide-gap semiconductor is SiC (silicon carbide), GaN (gallium nitride), or diamond.
11. A power conversion device comprising:
a DC power source; a plurality of main circuit switching elements constituting a positive arm and a negative arm which are bridge-connected so as to convert DC of the DC power source into AC; a plurality of high-speed diodes connected in reverse parallel to the main circuit switching elements, respectively; and a plurality of gate driving circuits that perform switching of the main circuit switching elements, respectively, at a desired timing,
the main circuit switching elements constituting the positive arm including a normally-on switching element, a normally-off switching element whose positive terminal is connected to the negative terminal of the normally-on switching element, and a cascode-connecting diode series-connected between the gate of the normally-on switching element and the normally-off switching element in a forward direction,
the main circuit switching elements constituting the negative arm including normally-on switching elements provided for respective phases, a normally-off switching element shared by respective phases and whose positive terminal is connected to the negative terminals of the normally-on switching elements, and a plurality of cascode-connecting diodes series-connected between each of the gates of the normally-on switching element and the negative terminal of the normally-off switching element, and
each of the gate driving circuit being connected to the gate of the normally-on switching element and the normally-off switching element constituting the main circuit switching element.
12. The power conversion device according to claim 11 , wherein
the gate driving circuit drives the normally-on switching element and the normally-off switching element in an independent manner.
13. The power conversion device according to claim 11 , wherein
withstand voltage of the normally-off switching element is set lower than that of the normally-on switching element.
14. The power conversion device according to claim 11 , wherein
withstand voltage of the cascode-connecting diode is set equal to that of the normally-off switching element.
15. The power conversion device according to claim 11 , wherein
the high-speed diode is a unipolar diode.
16. The power conversion device according to claim 15 , wherein
the unipolar diode is a Schottky Barrier Diode, a Junction Barrier Controlled Schottky Diode, or a Merged PiN Schottky Diode.
17. The power conversion device according to claim 11 , wherein
the normally-on switching element is constituted by a wide-gap semiconductor.
18. The power conversion device according to claim 17 , wherein
the wide-gap semiconductor is SiC (silicon carbide), GaN (gallium nitride), or diamond.
19. The power conversion device according to claim 11 , wherein
the high-speed diode is constituted by a wide-gap semiconductor.
20. The power conversion device according to claim 19 , wherein
the wide-gap semiconductor is SiC (silicon carbide), GaN (gallium nitride), or diamond.