Patent ID: 8712666

Claim:
A multiple-frequency inversion apparatus for an internal combustion engine driven generator, wherein it comprises: an output voltage rectifying unit configured to rectify the output voltage of a filter unit; an output voltage analog-to-digital conversion unit configured to perform analog-to-digital conversion for the rectified output voltage; an output voltage calculating unit configured to calculate the average value of the output voltage or the effective value of the output voltage according to the output voltage having undergone the analog-to-digital conversion; a comparing unit configured to compare the average value of the output voltage with a target voltage value or compare the effective value of the output voltage with a target voltage value; a control unit configured to, according to the comparison results, adjust the proportionality coefficient of two sine with a 180-degree phase difference in a table of sine until the average value or the effective value of the output voltage falls within a preset range of the target voltage value; the table of sine is used for generating two sine waves with a 180-degree phase difference, and the two sine waves with a 180-degree phase difference are compared with a triangle wave to generate four PWM waves which have pulse frequency f, and the triangle wave has a frequency f; the four PWM waves which have frequency f drive switching tubes in an inverter unit to enable the inverter unit to output modulated wave with a pulse frequency 2f.