Zero-voltage-switched multi-resonant converters including the buck and forward type

• US 4,857,822 A
• Filed: 04/11/1988
• Issued: 08/15/1989
• Est. Priority Date: 09/23/1987
• Status: Expired due to Fees

• Current Assignee: Virginia Tech Intellectual Properties, Inc.
• Original Assignee: Virginia Tech Intellectual Properties, Inc.
• Inventors: Lee, Fred C., Tabisz, Wojciech A.
• Primary Examiner(s): Wong, Peter S.
• Application Number:
  US07/179,926
• Time in Patent Office: 491 Days
• Field of Search: 323/235, 323/271, 323/282, 323/283, 323/284, 323/285, 323/286, 323/287, 323/290, 363/16, 363/39, 363/40, 363/44-48, 363/127
• US Class Current: 323/282
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• 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 multi-resonant-switching network that operates under switching conditions that are favorable to both the active switch and the diode that constitute the switch. In a zero-current multi-resonant switch, the resonant circuit is formed in a T-network with resonant inductors in series with the switching devices. In a zero-voltage multi-resonant switch, the resonant circuit is formed in a π-network with resonant capacitors connected in parallel with the switch. In this way, the two networks are dual. During operation of a multi-resonant converter, a multi-resonant switches forms three different resonant circuits depending on whether the active switch and diode are open or closed. This results in operation of the converter with three different resonant stages in one cycle of operation. In practicing the present invention, certain rules are applied to derive a ZVS-MRC from a PWM converter. In particular, one resonant capacitor is placed in parallel with the active switch, which may be either uni-directional or bi-directional, another resonant capacitor is placed in parallel with the rectifying diode, and an inductor is inserted in the loop containing the switch and the diode. This loop can also contain voltage sources and filter or blocking capacitors. Improvement in the operation of ZVS-MRCs is obtained with synchronous rectification which is achieved by replacing rectifying diodes in a DC/DC converter with active devices, called synchronous rectifiers.

Claims

1. A zero-voltage-switched multi-resonant converter comprising:

switching means operative in open and closed circuit positions;

first resonant capacitor means in parallel with said switching means;

rectifying diode means in series with said switching means, said rectifying means and said switching means forming a closed-loop;

second resonant capacitor means in parallel with said rectifying diode means; and

inductor means inserted in said closed loop for forming a resonant circuit with the first and second resonant capacitor means.

2. The converter of claim 1, wherein said rectifying diode means comprises a synchronous rectifier.

3. A zero-voltage-switched multi-resonant converter comprising:

switching means operative in open and closed circuit positions;

first resonant capacitor means in parallel with said switching means;

rectifying diode means;

second resonant capacitor means in parallel with said rectifying diode means; and

inductor means for forming a resonant circuit with said first and second resonant capacitor means.

4. The converter of claim 3, wherein said inductor means is inserted in series with said first and second resonant capacitor means, such that a first terminal of said inductor means is connected to said first resonant capacitor means, and a second terminal of said inductor means is connected to said second resonant capacitor means.