Switching element unit

A switching element unit, comprising:

• a series element unit made up of at least one set of a switching element and a diode element which are electrically connected in series to each other;
• and
• a smoothing capacitor configured to suppress fluctuation in DC voltage to be supplied to the series element unit, wherein
• the smoothing capacitor is a ceramic capacitor whose dielectric portion interposed between electrodes is formed of a ceramic material,
• outer surfaces of the smoothing capacitor include an element placement surface formed integrally with the dielectric portion,
• a first planar surface crossing the element placement surface at an end of the element placement surface which is located on one side in a reference direction that is set along the element placement surface, and
• a second planar surface crossing the element placement surface at an end of the element placement surface which is located on an other side in the reference direction, a positive terminal of the smoothing capacitor is formed on the first planar surface, and a negative terminal of the smoothing capacitor is formed on the second planar surface,
• a positive-side connection electrode that is electrically connected to the positive terminal and a negative-side connection electrode that is electrically connected to the negative terminal are formed on the element placement surface, and
• the switching element and the diode element of the series element unit are placed over the element placement surface, a positive-side terminal portion of the series element unit is electrically connected to the positive-side connection electrode, and a negative-side terminal portion of the series element unit is electrically connected to the negative-side connection electrode.

The switching element unit according to 11, wherein

• a connection portion between a positive-side element placed on a positive side, which is one of the switching element and the diode element of the series element unit, and a negative-side element placed on a negative side, which is an other of the switching element and the diode element of the series element unit, is an intermediate connection portion,
• the respective intermediate connection portions of a plurality of the series element units are electrically connected together to form a series element unit set,
• a direction perpendicular to the reference direction along the element placement surface is a reference perpendicular direction, and
• each of a plurality of the positive-side elements included in the same series element unit set is placed on the same side in the reference perpendicular direction with respect to the negative-side element forming the same series element unit.

The switching element unit according to 23, wherein

• a connection portion between a positive-side element placed on a positive side, which is one of the switching element and the diode element of the series element unit, and a negative-side element placed on a negative side, which is an other of the switching element and the diode element of the series element unit, is an intermediate connection portion,
• the respective intermediate connection portions of a plurality of the series element units are electrically connected together to form a series element unit set,
• a direction perpendicular to the reference direction along the element placement surface is a reference perpendicular direction, and
• each of a plurality of the positive-side elements included in the same series element unit set is placed on the same side in the reference perpendicular direction with respect to the negative-side element forming the same series element unit.