Three-level converter

A three-level converter, comprising:

• first input/output portions to which a first voltage is applied;
• second input/output portions to which a second voltage that is lower than the first voltage is applied;
• a switch circuit unit including first to fourth switch groups, each of which includes n switches connected in series, wherein n is an integer that is greater than or equal to two, the first switch group, the second switch group, the third switch group, and the fourth switch group being connected in series between the first input/output portions sequentially from a low potential side of the first input/output portions;
• an inductor connected to a high potential side of the second input/output portions and connected in series with the first switch group and the second switch group between the second input/output portions;
• a controller configured or programmed to output a control signal that controls the switches;
• a flying capacitor connected between a first connection point and a second connection point, the first connection point being located between the first switch group and the second switch group, and the second connection point being located between the third switch group and the fourth switch group;
• first drive circuits to activate and deactivate the switches in the first switch group and the second switch group based on the control signal;
• second drive circuits to activate and deactivate the switches in the third switch group and the fourth switch group based on the control signal;
• a first power supply connected to one of the first drive circuits, to activate and deactivate one of the switches located at a side of the first input/output portions in the first switch group, the first power supply being to supply a voltage to the one of the first drive circuits connected to the first power supply;
• first bootstrap circuits respectively connected to the first drive circuits excluding the one of the first drive circuits connected to the first power supply, each of the first bootstrap circuits being to supply a voltage to the connected one of the first drive circuits based on a voltage of the first power supply;
• a second power supply connected to one of the second drive circuits, to activate and deactivate one of the switches located at a side of the first input/output portions in the third switch group, the second power supply being to supply a voltage to the one of the second drive circuits connected to the second power supply;
• and
• second bootstrap circuits respectively connected to the second drive circuits excluding the one of the second drive circuits connected to the second power supply, each of the second bootstrap circuits being to supply a voltage to the connected one of the second drive circuits based on a voltage of the second power supply;
• wherein
• a cathode of a boot diode in one of the first bootstrap circuits, to drive one of the switches located at a lowest potential side in the second switch group, is connected to an anode of a boot diode in another one of the first bootstrap circuits in the second switch group;
• a cathode of a boot diode in one of the second bootstrap circuits, to drive one of the switches located at a lowest potential side in the fourth switch group, is connected to an anode of a boot diode in another one of the second bootstrap circuits in the fourth switch group;
• and
• the controller is configured or programmed to execute a first operation that complementarily drives the switches in the first switch group and the switches in the fourth switch group and complementarily drives the switches in the second switch group and the switches in the third switch group.