Self-regulated synchronous rectifier

• US 6,292,380 B2
• Filed: 11/30/2000
• Issued: 09/18/2001
• Est. Priority Date: 01/03/2000
• Status: Expired due to Term

• Current Assignee: Power Supply Systems Holdings (the Netherlands) B. V.
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Diallo, Almadidi, Ceunebrock, Patrick
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US09/725,847
• Publication Number:
  US 20010006471A1
• Time in Patent Office: 292 Days
• Field of Search: 363/89, 363/127, 363/84, 363/52, 363/53, 363/37, 363/17, 323/282, 323/284, 323/222
• US Class Current: 363/89
• 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 self-regulated synchronous rectifier is connected between a secondary transformer winding and an LC filter. The rectifier includes two MOSFETs each having a gate connected in series with a gate protection circuit. Each gate protection circuit includes a divider bridge and a switch connected in parallel with the divider bridge and having an open position and a closed position and the rectifier includes a control device for controlling the switches which receives an input signal proportional to the input voltage of the rectifier and produces output signals for controlling the switches.

Claims

1. A self-regulated synchronous rectifier connected between a secondary transformer winding and an LC filter and including two MOSFETs each having a gate connected in series with a gate protection circuit, wherein each gate protection circuit includes a divider bridge and a switch connected in parallel with said divider bridge and having an open position and a closed position, said rectifier including a control device for controlling said switches adapted to receive an input signal proportional to the input voltage of said rectifier and producing output signals for controlling said switches.

2. The self-regulated synchronous rectifier claimed in claim 1 when connected between the secondary transformer winding, which has first and second transformer ends, and said LC filter, which has first and second filter inputs, wherein said self-regulated synchronous rectifier has:

first and second rectifier inputs respectively connected to said first and second transformer ends,

first and second rectifier outputs, said second rectifier output being connected to said second rectifier input,

said direct MOSFET connected between said first rectifier input and said first rectifier output and having a gate connected to said second rectifier input and in series with said gate protection circuit, and

said freewheel MOSFET connected between said first rectifier output and said second rectifier output and having a gate connected to said first rectifier input and in series with said gate protection circuit.

3. The self-regulated synchronous rectifier claimed in claim 1 wherein said secondary winding of said transformer includes first and second sub-windings of opposite phase, each of said sub-windings having first and second transformer ends, and an LC filter having first and second filter inputs, wherein said self-regulated synchronous rectifier includes:

first and second rectifier inputs respectively connected to said transformer ends of said first sub-winding defining a first subsystem,

first and second rectifier inputs respectively connected to said transformer ends of said second sub-winding defining a second subsystem,

first and second rectifier outputs, said second rectifier output being connected to said second rectifier input of said first subsystem,

one MOSFET connected between said first rectifier input of said first subsystem and said first rectifier output and having a gate connected to said second rectifier input of said first subsystem and in series with said gate protection circuit, and

the other MOSFET connected between said first rectifier input of said second subsystem and said first rectifier output and having a gate connected to said second rectifier input of said second subsystem and in series with said gate protection circuit.

4. The self-regulated synchronous rectifier claimed in claim 1 wherein said control device generates two output signals independent of each other and each signal controls one of said switches.

5. The self-regulated synchronous rectifier claimed in claim 1 wherein said control device generates two interdependent output signals and each signal controls one of said switches.

6. The self-regulated synchronous rectifier claimed in claim 1 wherein said control device includes means for generating at least one threshold value and means for comparing said input signal proportional to said rectifier input voltage with said threshold value and said output signals are a function of the direction of the comparison between said input signal proportional to said rectifier input voltage and said threshold value.

7. The self-regulated synchronous rectifier claimed in claim 1 including voltage measuring means including a diode connected in series with a measurement capacitor between said second rectifier input and said first rectifier output and wherein said input signal is taken off between said diode and said measurement capacitor.