Single-switch, high power factor, ac-to-ac power converters

• US 6,008,589 A
• Filed: 03/05/1996
• Issued: 12/28/1999
• Est. Priority Date: 03/05/1996
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Deng, Edward E., Cuk, Slobodan
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US08/611,990
• Time in Patent Office: 1,393 Days
• Field of Search: 315/307, 315/247, 315/219, 315/205, 315/209 R, 315/291, 363/34, 363/37, 363/39, 363/40, 363/44, 363/47, 363/48, 363/24, 363/25, 363/26
• US Class Current: 315/209.00R
• CPC Class Codes: H02M 1/425 using a single converter stage both for correction of AC input power factor and generation of a high frequency AC output voltage
• CPC Class Codes: H05B 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A single-switch ac-to-ac converters for driving ac loads which are particularly suitable for gas discharge lamp ballast applications based upon integration of automatic current shapers and converters that resemble a class-E converter, both parts sharing a single active switch. The first part comprises a high power factor (HPF) converter having automatic input current-shaping means and internal energy storage means operated by the single active switch driven at a constant frequency and duty ratio, and the second part comprises a resonant converter means operated by the aforesaid single active switch as it is being driven. Integration of the HPF converter having automatic current shaping means and the resonant converter through the single active switch operation brings advantages from both parts into the whole circuit, such as soft-switching characteristics so that the combined circuit can shape the input current without switching losses in a compact structure.

Claims

1. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load, said ac-to-ac converter comprising first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier and a lowpass LC filter for providing rectified sinewave voltage from said ac power line voltage, a first fast recovery diode and input inductor connected in series with said single switch to a return current path for said lowpass LC filter, an energy storage and transfer capacitor and a second fast recovery diode in series, and in that order, connected in parallel across said input inductor from said single active switch to said first fast recovery diode, a second inductor connected in parallel across said energy storage and transfer capacitor and said single active switch and a capacitor connected in parallel across said single active switch.

2. A high power factor ac-to-ac converter as defined in claim 1 wherein said high frequency load is a gas discharge lamp.

3. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load, said ac-to-ac converter comprising first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier and a lowpass LC filter for providing rectified sinewave voltage from said ac power line voltage, a fast recovery diode and input inductor connected in series with said single switch to a return current path for said lowpass LC filter through an energy storage and transfer capacitor and an inductor connected in parallel across said single active switch, and a second capacitor connected in parallel across said single active switch.

4. A high power factor ac-to-ac converter as defined in claim 3 wherein said high frequency load is a gas discharge lamp.

5. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprises an input network means and dual active switches operated out of phase at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of sinewave input voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprises said dual active switches and an output network means for operating on said sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said pulsed, half sinewave voltage to said high frequency load and converting said pulsed voltage to the high frequency ac voltage for driving said ac load,

wherein said input network means of said first part comprises a bridge rectifier and an LC filter for providing rectified sinewave voltage, a fast recovery diode connected in series to each of two input inductors operating in a discontinuance conduction mode, each inductor being connected in series to a return current path for said LC filter through a separate one of said dual switches, a transformer having a center tapped primary winding and a secondary winding, said primary winding being connected between separate junctions of said two input inductors and said dual switches, an energy storage capacitor and a choke inductor connected in series between the center tap of said primary winding and said return current path, a resonant capacitor connected in parallel across said center tapped primary winding, and a capacitor connected in series with said high frequency ac load across said secondary winding.

6. A high power factor ac-to-ac converter as defined in claim 5 wherein said high frequency ac load is a gas discharge lamp.

7. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier for providing rectified sinewave voltage from said ac power line voltage, a fast recovery diode and first inductor connected in series with said single active switch to a return current path for said bridge rectifier, a first capacitor and said ac load both being connected in parallel with said single active switch, a second capacitor and second fast recovery diode connected in series with an energy storage capacitor to said return current path, a second inductor connecting a junction between said energy storage capacitor and said second fast recovery diode to a junction between said first fast recovery diode and said single active switch, and a third inductor having one terminal connected to a junction between said second capacitor and a second terminal connected to said return current path, and magnetic means coupling said third inductor to said first inductor for steering switching ripple current from said first inductor to said third inductor.

8. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier for providing rectified sinewave voltage from said ac power line voltage, a first inductor and a fast recovery diode connected in series with said single active switch to a return current path for said bridge rectifier, an energy storage capacitor and a second inductor connected in series through a second capacitor to said return current path, a second fast recovery diode connecting a first junction between said second inductor and said energy storage capacitor to said return current path, a third capacitor and said ac load both being connected in parallel across said single active switch, and a third inductor having a first terminal connected to said first junction, and a second terminal connected to a second junction between said single active switch and said first fast diode, and magnetic means coupling said first inductor and said second inductor for steering ripple current out from said first inductor to said second inductor.

9. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier for providing rectified sinewave voltage from said ac power line voltage, a first inductor and a first fast recovery diode connected in series with said single active switch to a return current path for said bridge rectifier, said ac load being connected in parallel across said single active switch, a second fast recovery diode and an energy storage capacitor connected in series with said first inductor from said bridge rectifier to said return current path for said bridge rectifier, a second capacitor connected in parallel with said single active switch, a third inductor coupling a junction between said first fast recovery diode and said single active switch to a junction between said second fast recovery diode and said energy storage capacitor, and magnetic means coupling said first inductor to a second inductor for steering switching ripple current out from said first inductor to said second inductor.

10. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier for providing rectified sinewave voltage from said ac power line voltage, a first inductor and a first fast recovery diode connected in series with said single active switch to a return current path for said bridge rectifier, a second inductor and a first capacitor connected in parallel across said first fast recovery diode and said single active switch, said ac load being connected in parallel across said single active switch, a second capacitor connected in parallel across said single active switch, a third inductor and an energy storage capacitor in series connected across said single active switch, and magnetic means coupling said first inductor to said second inductor for steering switching ripple current out from said first inductor to said second inductor.

11. A high power factor ac-to-ac converter for converting low frequency ac power line voltage to high frequency voltage for a high frequency ac load with a resonant matching network, wherein said ac-to-ac converter comprises first and second overlapping parts,

said first part comprising an input network means and a single active switch operated at a high constant frequency and a constant duty ratio for automatic sinewave current shaping by rectification of input sinewave voltage and yielding rectified sinewave current for conversion to high frequency pulsed, half sinewave voltage in said second part, and

said second part comprising said single active switch and an output network means for operating on said rectified sinewave current from said first part to convert it to high frequency pulsed, half sinewave voltage and a resonant matching network means for coupling said high frequency pulsed, half sinewave voltage to said high frequency ac load and converting said pulsed voltage to high frequency ac voltage for driving said ac load,

wherein said input network of said first part comprises a bridge rectifier for providing rectified sinewave voltage from said ac power line voltage, a first inductor and a fast recovery diode connected in series with said single active switch to a return current path for said bridge rectifier, a capacitor and said ac load connected in parallel across said single active switch, a second inductor and second capacitor connected in series from a junction between said first inductor and said fast recovery diode to said return current path through an energy storage capacitor, and a third inductor coupling a junction between said second capacitor and said energy storage capacitor to a junction between said fast recovery diode and said single active switch, and magnetic means coupling said first inductor to said second inductor for steering switching ripple current from said first inductor to said second inductor.