Control of power conversion device for decreasing total harmonic distortion

A power conversion device, comprising:

• a plurality of power conversion modules being connected in parallel to receive input power and provide output AC power;
• and
• a frequency controller configured to control each operating frequency of the plurality of power conversion modules,
• wherein, the frequency controller includes a function as a first frequency regulating step for regulating each operating frequency of the plurality of power conversion modules, so that the operating frequencies of the plurality of power conversion modules have a specific relationship with each other,
• wherein, in the first frequency regulating step, the frequency controller regulates a difference among the operating frequencies of the plurality of power conversion modules so as to be m times a frequency of the output AC power, where m is one of 0 or an even number, and
• wherein a difference between operating frequencies of at least two power conversion modules among the plurality of power conversion modules is not zero.

A power conversion device, comprising:

• a plurality of power conversion modules being connected in parallel to receive input power and provide output AC power;
• and
• a frequency controller configured to control each operating frequency of the plurality of power conversion modules,
• wherein, the frequency controller includes a function as a first frequency regulating step for regulating each operating frequency of the plurality of power conversion modules, so that the operating frequencies of the plurality of power conversion modules have a specific relationship with each other, and
• wherein, in the first frequency regulating step, the frequency controller regulates each of the plurality of power conversion modules to be operated at any one of a first operating frequency or a second operating frequency, and a difference between the first operating frequency and the second operating frequency to be 2 times a frequency of the output AC power.

A frequency controller configured to control each operating frequency of a plurality of power conversion modules connected in parallel which receive input power and supply output AC power, the frequency controller comprising:

• an information obtainer configured to obtain information for the output AC power;
• and
• a frequency regulator configured to perform a first frequency regulating step for regulating each operating frequency of the plurality of power conversion modules so that each operating frequency of the plurality of power conversion modules have a specific relationship with each other,
• wherein, in the first frequency regulating step, the frequency regulator regulates a difference among the operating frequencies of the plurality of power conversion modules so as to be m times a frequency of the output AC power, where m is one of 0 or an even number, and
• wherein a difference between operating frequencies of at least two power conversion modules among the plurality of power conversion modules is not zero.

A frequency controller configured to control each operating frequency of a plurality of power conversion modules connected in parallel which receive input power and supply output AC power, the frequency controller comprising:

• an information obtainer configured to obtain information for the output AC power;
• and
• a frequency regulator configured to perform a first frequency regulating step for regulating each operating frequency of the plurality of power conversion modules so that each operating frequency of the plurality of power conversion modules have a specific relationship with each other,
• wherein, in the first frequency regulating step, the frequency regulator regulates each of the plurality of power conversion modules to be operated at any one of a first operating frequency or a second operating frequency, and a difference between the first operating frequency and the second operating frequency to be 2 times a frequency of the output AC power.

A method for controlling operating frequencies of a plurality of power conversion modules by a frequency controller connected in parallel which receive input power and supply output AC power, the method comprising:

• performing a first frequency regulating step for controlling each of the plurality of power conversion modules to be operated at any one of a first operating frequency or a second operating frequency;
• and
• performing a second frequency regulating step for obtaining information for a voltage or a current of the output AC power, calculating a THD (Total Harmonic Distortion) of the voltage or the current, and finely regulating each operating frequency of the plurality of power conversion modules to decrease the calculated THD,
• wherein, a difference between the first operating frequency and the second operating frequency is 2 times a frequency of the output AC power.