Power conversion device, power conversion method, and program

A power conversion device, comprising:

• a matrix converter circuit including a plurality of switching elements, the matrix converter circuit being configured to perform bidirectional power conversion between alternating current power on a primary side and alternating current power on a secondary side;
• a power conversion control unit configured to switch on and off, in unison with a carrier wave, the plurality of switching elements to cause a voltage or a current on the secondary side to follow a control command;
• and
• a carrier wave changing unit configured to change, based on a nearness level of a frequency of the voltage or the current on the secondary side to a frequency of a voltage on the primary side, a frequency of the carrier wave, wherein
• a variable range of the frequency of the voltage or the current on the secondary side provided by the power conversion control unit includes a first frequency band including the same frequency as the frequency of the voltage on the primary side, a second frequency band lower than the first frequency band, and a third frequency band higher than the first frequency band,
• when the frequency of the voltage or the current on the secondary side is within the second frequency band, or when the frequency of the voltage or the current on the secondary side is within the third frequency band, the carrier wave changing unit sets the frequency of the carrier wave to a first carrier frequency, and
• when the frequency of the voltage or the current on the secondary side is within the first frequency band, the carrier wave changing unit sets the frequency of the carrier wave to a second carrier frequency lower than the first carrier frequency.

A power conversion method, comprising:

• switching on and off, in unison with a carrier wave, a plurality of switching elements of a matrix converter circuit to cause a voltage or a current on a secondary side of the matrix converter circuit to follow a control command, the matrix converter circuit being configured to perform bidirectional power conversion between alternating current power on a primary side and alternating current power on the secondary side;
• and
• changing, based on a nearness level of a frequency of the voltage or the current on the secondary side to a frequency of a voltage on the primary side, a frequency of the carrier wave, wherein
• a variable range of the frequency of the voltage or the current on the secondary side provided by a power conversion control unit includes a first frequency band including the same frequency as the frequency of the voltage on the primary side, a second frequency band lower than the first frequency band, and a third frequency band higher than the first frequency band, and
• the power conversion method further comprises:
• when the frequency of the voltage or the current on the secondary side is within the second frequency band, or when the frequency of the voltage or the current on the secondary side is within the third frequency band, setting the frequency of the carrier wave to a first carrier frequency;
• and
• when the frequency of the voltage or the current on the secondary side is within the first frequency band, setting the frequency of the carrier wave to a second carrier frequency lower than the first carrier frequency.