Power conditioner

A power conditioner comprising:

• a first chopper circuit comprising a first switch circuit including series connected first and second switches, the first and second switches configured to be alternately turned on and off at a first chopping frequency, chop a DC voltage from a DC power source, and generate a first pulse voltage series having a first voltage in which a voltage level becomes a positive value with respect to a first reference potential;
• a second chopper circuit comprising a parallel-connected circuit that includes a second capacitor and a second switch circuit in which one side of a parallel connection of the parallel-connected circuit is connected to the series-connected portion of the first and second switches, the second switch circuit formed by connecting third and fourth switches in series, the third and fourth switches configured to be alternately turned on and off at a second chopping frequency, the third and fourth switches configured to chop an output of the first chopper circuit while the first pulse voltage series is set to a second reference potential, and generate a second pulse voltage series having a second voltage, a voltage level of the second voltage being lower than that of the first pulse voltage series, the second voltage becoming a negative side value with respect to the second reference potential, the third and fourth switches further configured to add the first and second voltages at of the first and second pulse voltage series to form a third pulse voltage series that changes alternately in a sinusoidal manner between positive and negative values with respect to the first reference potential;
• a third chopper circuit comprising series-connected fifth and sixth switches in which a series-connected portion of the fifth and sixth switches is connected to a series-connected portion of the third and fourth switches, the fifth and sixth switches configured to be alternately turned on and off at a third chopping frequency, and perform a charge and discharge output by chopping the third pulse voltage series according to positive and negative voltage differences with a sinusoidal voltage, the third chopper circuit further including series connected seventh and eighth switches, wherein the third chopper circuit turns on and off the seventh and eighth switches at a pulse width modulation (PWM) frequency higher than the third chopping frequency so as to correct a difference between the third pulse voltage series and the sinusoidal voltage, and the third chopper circuit controls on/off duty cycles of the seventh and eighth switches to control the charge and discharge output so as to obtain the sinusoidal voltage that changes continuously between the positive and negative values of the first reference potential;
• and
• a controller processor configured to calculate an offset between a timing of chopping of the third pulse voltage series according to a positive and negative voltage difference with the sinusoidal voltage and a timing of the switching between on/off duty cycles of the seventh and eighth switch, and controls the on/off duty cycles of the seventh and eighth switches according to the calculated offset.