Zero-voltage-transition pulse-width-modulated converters

• US 5,418,704 A
• Filed: 05/24/1993
• Issued: 05/23/1995
• Est. Priority Date: 06/12/1992
• Status: Expired due to Fees

• Current Assignee: Virginia Tech Intellectual Properties, Inc.
• Original Assignee: The Center For Innovative Technology
• Inventors: Lee, Fred C., Hua, Guichao C.
• Primary Examiner(s): Dougherty, Thomas M.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/066,943
• Time in Patent Office: 729 Days
• Field of Search: 363/16, 363/20, 363/21, 323/222, 323/224, 323/282, 323/351
• US Class Current: 323/282
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• 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

To date, soft-switching techniques applied to the PWM converters, with the exception of a few isolated cases, are subjected to either high switch voltage stresses or high switch current stresses, or both. This invention presents a new class of zero-voltage-transition PWM converters, where both the transistor and the rectifier operate with zero-voltage switching, and are subjected to minimum voltage and current stresses. Breadboarded converters are constructed to verify the novelty of the proposed new family of converters.

Claims

1. A pulse-width-modulated d.c. to d.c. converter comprising in combination:

a d.c. voltage input means;

a d.c. voltage output means including an output filter and a rectifier diode;

a pulse-width-modulating switch connected between said d.c. voltage input means and said d.c. voltage output means;

a resonant circuit comprised of a capacitance, an inductance, and an auxiliary switch;

means connecting said resonant circuit in parallel with pulse-width-modulating switch;

a pulse-width-modulating signal source with means connecting said signal source to said pulse-width-modulating switch, and means connecting said signal source to said auxiliary switch;

said pulse-width-modulating signal source switching said pulse-width-modulating switch between an on state and an off state at a fixed frequency and a varying duty cycle;

said auxiliary switch being switched to an on state prior to said pulse-width-modulating switch being switched to an on state so that said auxiliary switch is in said on state a sufficient interval that said resonant circuit establishes a substantially zero voltage across said pulse-width-modulating switch when said pulse-width-modulating switch switches to an on state and said auxiliary switch being switched back to an off state for an interval after said pulse-width-modulating switch switches to an on state in order to control the resonance of said resonant circuit, whereby the pulse-width-modulating switch operates at a constant frequency with zero voltage switching of said pulse width-modulating switch and said rectifier diode over wide load range.

2. A pulse-width-modulated d.c. to d.c. converter comprising in combination:

a d.c. voltage input means;

a d.c. voltage output means including an output filter and a rectifier diode;

a pulse-width-modulating switch connected between said d.c. voltage input means and said d.c. voltage output means;

a resonant circuit comprised of a capacitance, an inductance, and an auxiliary switch;

means connecting said resonant circuit in parallel with pulse-width-modulating switch and means connecting a node of said resonant circuit to a terminal of said rectifier diode;

a pulse-width-modulating signal source with means connecting said signal source to said pulse-width-modulating switch, and means connecting said signal source to said auxiliary switch;

said pulse-width-modulating signal source switching said pulse-width-modulating switch between an on state and an off state at a fixed frequency and a varying duty cycle;

said auxiliary switch being switched to an on state prior to said pulse-width-modulating switch being switched to an on state so that said auxiliary switch is in said on state a sufficient interval that said resonant circuit establishes a substantially zero voltage across said pulse-width-modulating switch when said pulse-width-modulating switch switches to an on state and said auxiliary switch being switched back to an off state for an interval after said pulse-width-modulating switch switches to an on state in order to control the resonance of said resonant circuit, whereby the pulse-width-modulating switch operates at a constant frequency with zero voltage switching of said pulse-width-modulating switch and said rectifier diode over wide load range.