Patent ID: 8300438

Claim:
A 3-phase pfc ac-dc power converter comprising a 3-phase boost converter, a first control circuit for operating the 3-phase boost converter at “0% duty-ratio”, such that where X is a phase angle of a 3-phase sine wave voltage, a phase A boost duty-ratio D boost a is approximately D boost ⁢ a = 1 -  Sin ⁢ ⁢ X  max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } a phase B boost duty-ratio D boost b is approximately D boost ⁢ b = 1 -  Sin ⁡ ( X + 120 )  max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } and a phase C boost duty-ratio D boost c is approximately D boost ⁢ c = 1 -  Sin ⁡ ( X + 240 )  max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } a 3-phase buck converter, and a second control circuit for operating the 3-phase buck converter at “100% duty-ratio,” such that where X is a phase angle of a 3-phase sine wave voltage, a phase A buck duty-ratio D buck a is approximately D buck ⁢ a = Sin ⁢ ⁢ X max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } a phase B buck D buck b duty-ratio is approximately D buck ⁢ b = Sin ⁡ ( X + 120 ) max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } and a phase C buck duty-ratio D buck c is approximately D buck ⁢ c = Sin ⁡ ( X + 240 ) max ⁢ {  Sin ⁢ ⁢ X  ,  Sin ⁡ ( X + 120 )  ,  Sin ⁡ ( X + 240 )  } the 3-phase boost converter and the 3-phase buck converter being connected with their respective 3-phase inputs in parallel and with their outputs in series to reduce the ripple voltage in the output voltage.