Resonant power converter with primary-side tuning and zero-current switching

• US 6,490,177 B1
• Filed: 06/30/2000
• Issued: 12/03/2002
• Est. Priority Date: 10/05/1998
• Status: Expired due to Fees

• Current Assignee: Salvador Figueroa
• Original Assignee: Salvador Figueroa
• Inventors: Figueroa, Salvador
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/607,368
• Time in Patent Office: 886 Days
• Field of Search: 363/97, 363/131, 363/21.03, 363/20, 363/16
• US Class Current: 363/21.03
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• 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 DC power converter consisting of a series-resonant branch used to transform a DC voltage source into a DC current source exhibiting, a uni-polar, zero-current-switching characteristic. Frequency of the series-resonant branch, acting in concert with reflected load parameters, provides a forced oscillation frequency, Fo, component to an AC voltage source generated across the input winding of a power transformer by the resonant capacitor. Complex load parameters allow AC input current, displaced by 90° from the AC voltage source, to flow in the transformer primary winding throughout a composite, carrier-frequency cycle. Another component of the carrier-frequency consists of a resonant, natural oscillation frequency, Fn, resulting from resonance by the AC voltage source capacitance with the open-circuit inductance of the primary winding on the input power transformer. The composite carrier-frequency, Fo+Fn, transported through the input power transformer is directed to a rectifier/filter assembly and applied as a DC voltage to an output load. Thus, the uni-polar DC series-resonant branch is converted into an AC power transfer function, fully isolated from the input power switch, by the AC voltage source capacitor. The power transfer function characterizing a bi-polar power inverter requires a single power switch referenced to the input power return bus.

Claims

1. A resonant power converter with AC full-wave primary-side resonance and zero-current switching adapted to convert power from an input DC voltage source to a DC terminal output load comprising:

an input stage configured to receive a first power signal from a DC input source;

an AC full-wave magnetic interface configured to receive a second power signal from said input stage;

an output stage configured to impose an output signal across a load by receiving said second power signal from said magnetic interface; and

wherein said input stage includes a zero-current switch topology comprising a resonant capacitor, a resonant inductor and a unidirectional conducting device with a switching element arranged in series within said zero-current switch.

2. The resonant power converter of claim 1 wherein said magnetic interface further comprises:

an input winding and a non-polarized output winding wherein said input winding is connected to said input stage and said output winding is connected to said output stage.

3. The resonant power converter of claim 2 wherein said magnetic interface input winding is connected in parallel with said resonant capacitor.

4. The resonant power converter of claim 2 wherein said output stage further comprises:

a rectifying element, a filter inductor connected to said rectifying element, a filter capacitor connected to said filter inductor and a fly-back rectifying element connected to said filter inductor.

5. The resonant power converter of claim 4 wherein said output stage filtering elements may be implemented in any combination of half or full-wave rectifier/filter configuration.

6. The resonant power converter of claim 1 further comprising:

a control mechanism connected to said zero-current switch configured to selectively vary said switching element between an open and a closed position.

7. The resonant power converter of claim 6 wherein said control mechanism comprises a pulse-position-modulation (PPM) control mode as a negative feedback loop.

8. The resonant power converter of claim 6 wherein said PPM control mode further comprises:

a sensor configured to open said switching element upon cessation of current in said zero-current switch.

9. The resonant power converter of claim 3 further comprising:

a power transfer function wherein said resonant capacitor offers a full-wave AC voltage source to said input winding of said magnetic interface in isolation from said switching element situated within said zero-current switch.

10. The resonant power converter of claim 7 wherein said PPM control mode initiates a forced frequency, Fo, component upon said resonant capacitor and said magnetic interface input winding during the positive region of the full-wave sinusoidal transition.

11. The resonant power converter of claim 7 wherein said PPM control mode initiates a resonant frequency, Fn, component upon said resonant capacitor and said magnetic interface input winding during the negative region of the full-wave sinusoidal transition.

12. The resonant power converter of claim 7 wherein said PPM control mode combines said forced frequency, Fo, with said resonant frequency, Fn, to synthesize a composite full-wave sinusoidal carrier-frequency comprised of said frequency component Fo, and said frequency component, Fn.

13. The resonant power converter of claim 11 wherein peak voltage amplitude of said resonant component, Fn, appears additive with said input DC voltage source to impose the hold-off voltage sustained by said unidirectional conducting device in combination with said switching element within said zero-current switch.

14. The resonant power converter of claim 12 wherein a design coefficient, K, introduces a maximum duty cycle [1/(1+K)] allowed by said PPM control on said zero-current switch.

15. The resonant power converter of claim 7 wherein said PPM negative feedback control loop monitors said output signal across said load and upon sensing an out-of-limit deviation alters time between pulses to said switching element to restore said output signal within prescribed limits.