Power switcher, power rectifier, and power converter including cascode-connected transistors

A power rectifier, comprising:

• first and second input terminals to which an AC input voltage is applied;
• first and second output terminals from which a rectified voltage is output;
• and
• a first power switcher connected between the first or second input terminal and the first or second output terminal, wherein the first power switcher comprises
• a first normally-off transistor including a first electrode, second electrode and a first control electrode, the first normally-off transistor switching between interrupting and not interrupting a current path between first and second electrodes according to a drive voltage input to the first control electrode,
• a second normally-on transistor cascode-connected to the first normally-off transistor and including a second control electrode to which the second electrode of the first normally-off transistor is connected,
• a control voltage generator that generates a control voltage in accordance with a voltage between the first and second electrodes of the first normally-off transistor, and
• a drive voltage generator that generates the drive voltage equal to or lower than a withstand voltage of the first normally-off transistor in accordance with the control voltage,
• wherein
• the second electrode is connected to the first or second input terminal, a third electrode of the second normally-on transistor is connected to the first or second output terminal,
• the second control electrode is applied with a voltage between the first electrode and the second electrode of the first normally-off transistor, and the first electrode is a drain, and the second electrode is a source.

A power converter, comprising:

• first and second input terminals to which an AC input voltage is applied;
• a plurality of AC-DC converters connected in series between the first and second input terminals and each converting a divided input voltage, which is obtained by dividing the AC input voltage, to a full-wave rectified voltage in an electrically isolated state;
• and
• first and second output terminals from which the full-wave rectified voltage converted by the plurality of AC-DC converters is output, wherein
• the AC-DC converters each comprise
• a power rectifier that rectifies the divided input voltage, and
• a DC-DC converter that converts a voltage level of an output voltage of the power rectifier,
• the power rectifier comprises a first power switcher,
• the first power switcher comprises
• a first normally-off transistor including a first electrode, a second electrode and the first control electrode, the first normally-off transistor switching between interrupting and not interrupting a current path between the first and second electrodes according to a drive voltage input to the first control electrode,
• a second normally-on transistor cascode-connected to the first normally-off transistor and including a second control electrode to which the second electrode of the first normally-off transistor is connected,
• a control voltage generator that generates a control voltage in accordance with a voltage between the first and second electrodes of the first normally-off transistor, and
• a drive voltage generator that generates the drive voltage having a withstand voltage equal to or lower than the withstand voltage of the first normally-off transistor in accordance with the control voltage,
• the divided input voltage is input to the second electrode,
• a voltage output from a third electrode of the second normally-on transistor is input to the DC-DC converter,
• the second control electrode is applied with a voltage between the first electrode and the second electrode of the first normally-off transistor, and
• the first electrode is a drain, and the second electrode is a source.