LOW FORWARD VOLTAGE RECTIFIER USING CAPACITIVE CURRENT SPLITTING

• US 20130249529A1
• Filed: 05/22/2013
• Published: 09/26/2013
• Est. Priority Date: 10/29/2011
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: IXYS Corporation (Littelfuse Incorporated)
• Inventors: Seok, Kyoung Wook
• Granted Patent: US 9,042,143 B2
• Time in Patent Office: Days
• US Class Current: 323/364
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• CPC Class Codes: H01L 27/0664 Vertical bipolar transistor in combination with diodes
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/083 for the ignition at the zero crossing of the voltage or the current
• 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: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• CPC Class Codes: H05K 13/00 Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
• 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
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A Low Forward Voltage Rectifier (LFVR) circuit includes a bipolar transistor, a parallel diode, and a capacitive current splitting network. The LFVR circuit, when it is performing a rectifying function, conducts the forward current from a first node to a second node provided that the voltage from the first node to the second node is adequately positive. The capacitive current splitting network causes a portion of the forward current to be a base current of the bipolar transistor, thereby biasing the transistor so that the forward current experiences a low forward voltage drop across the transistor. The LFVR circuit sees use in as a rectifier in many different types of switching power converters, including in flyback, Cuk, SEPIC, boost, buck-boost, PFC, half-bridge resonant, and full-bridge resonant converters. Due to the low forward voltage drop across the LFVR, converter efficiency is improved.

Claims

1. A switching power converter circuit comprising:

a first capacitor having first terminal and a second terminal;

a second capacitor having a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to first terminal of the first capacitor at a first node;

a bipolar transistor having a base, a collector, and an emitter, wherein the collector is coupled to the second terminal of the second capacitor, wherein the base is coupled to the second terminal of the first capacitor;

a diode having an anode and a cathode, wherein the anode is coupled to the collector of the bipolar transistor, wherein the cathode is coupled to the emitter of the bipolar transistor at a second node;

a first inductor having a first terminal and second terminal, wherein the first terminal of the first inductor is coupled to the collector of the bipolar transistor; and

a second inductor having a first terminal and second terminal, wherein the first terminal of the second inductor is coupled to the base of the bipolar transistor, wherein the second terminal of the second inductor is coupled to the second terminal of the first inductor at a third node.

2. The switching power converter circuit of claim 1, wherein the switching power converter circuit is taken from the group consisting of:

a flyback converter, a Cuk converter, a SEPIC converter, a boost converter, a buck-boost converter, a power factor correction circuit, a half-bridge resonant converter, a full-bridge resonant converter.

3. The switching power converter circuit of claim 1, wherein the first capacitor has a capacitance that is substantially smaller than a capacitance of the second capacitor.

4. The switching power converter circuit of claim 1, wherein the first inductor has an inductance that is substantially smaller than an inductance of the second inductor.

5. The switching power converter circuit of claim 1, further comprising:

an output capacitor having a first terminal and a second terminal, wherein the first terminal of the output capacitor is coupled first terminals of the first and second capacitors at the first node.

6. The switching power converter circuit of claim 1, further comprising:

an output capacitor having a first terminal and a second terminal, wherein the second terminal of the output capacitor is coupled to the second terminals of the first and second inductors at the third node.

7. The switching power converter circuit of claim 1, further comprising:

a transformer winding coupled between the emitter of the bipolar transistor and the first terminals of the first and second capacitors.

8. The switching power converter circuit of claim 1, further comprising:

a switch having a first terminal, a second terminal, and a third terminal, wherein the first terminal of the switch is coupled to the first terminals of the first and second capacitors, and wherein the second terminal of the switch is coupled to the emitter of the bipolar transistor.

9. The switching power converter circuit of claim 1, further comprising:

a switch having a first terminal, a second terminal, and a third terminal, wherein the first terminal of the switch is coupled to the first terminals of the first and second capacitors, and wherein the second terminal of the switch is coupled to the second terminals of the first and second inductors.

10. The switching power converter circuit of claim 1, further comprising:

an output capacitor having a first terminal and a second terminal, wherein the first terminal of the output capacitor is coupled to the emitter of the bipolar transistor, and wherein the second terminal of the output capacitor is coupled to the second terminals of the first and second inductors.

11. A switching power converter circuit comprising:

a first capacitor having first terminal and a second terminal;

a second capacitor having a first terminal and a second terminal;

a bipolar transistor having a base, a collector, and an emitter, wherein the collector is coupled to the second terminal of the second capacitor, wherein the base is coupled to the second terminal of the first capacitor;

a diode having an anode and a cathode, wherein the anode is coupled to the collector of the bipolar transistor, wherein the cathode is coupled to the emitter of the bipolar transistor;

a first inductor having a first terminal and second terminal, wherein the first terminal is coupled to the collector of the bipolar transistor; and

a second inductor having a first terminal and second terminal, wherein the first terminal is coupled to the base of the bipolar transistor, wherein the switching power converter circuit is taken from the group consisting of;

a flyback converter, a Cuk converter, a SEPIC converter, a boost converter, a buck-boost converter, a power factor correction converter circuit, a half-bridge resonant converter, a full-bridge resonant converter.

12. A method of manufacture comprising:

(a) providing a first capacitor, a second capacitor, a bipolar transistor and a diode, such that the first capacitor is electrically coupled between a first node and a base of the bipolar transistor, such that the second capacitor that is electrically coupled between the first node and a collector of the bipolar transistor, such that an anode of the diode is coupled to a collector of the bipolar transistor, and such that a cathode of the diode is coupled to an emitter of the bipolar transistor at a second node, wherein the first capacitor, second capacitor, bipolar transistor, and diode are parts of a switching power converter circuit.

13. The method of manufacture of claim 12, further comprising:

(b) providing a first inductor such that the first inductor is electrically coupled between the collector of the bipolar transistors and a third node; and

(c) providing a second inductor such that the second inductor is electrically coupled between the base of the bipolar transistors and the third node.

14. The method of manufacture of claim 13, wherein (a), (b) and (c) involve attaching the first capacitor, the second capacitor, the bipolar transistor, the diode, the first inductor, and the second inductor to a substrate.

15. A switching power converter circuit comprising:

a bipolar transistor having a base, a collector, and an emitter; and

means for receiving a current from a first node and for capacitively splitting the current so that a first portion of the current is supplied by the means to the base of the bipolar transistor and so that a second portion of the current is supplied by the means to the collector of the bipolar transistor.

16. The switching power converter circuit of claim 15, wherein the means comprises:

a first inductor coupled to the collector of the bipolar transistor, and a second inductor coupled to the base of the bipolar transistor.

17. The switching power converter circuit of claim 15, wherein the means comprises:

a first capacitor coupled to the base of the bipolar transistor, and a second capacitor coupled to the collector of the bipolar transistor.

18. The switching power converter circuit of claim 15, further comprising:

a diode having an anode and a cathode, wherein the anode is coupled to one of the collector and the emitter of the bipolar transistor, and wherein the cathode is coupled to the other of the collector and emitter of the bipolar transistor.

19. The switching power converter circuit of claim 15, wherein the first portion is substantially smaller than the second portion.

20. The switching power converter circuit of claim 15, wherein the magnitude of the first portion is a substantially fixed fraction of the magnitude of the second portion.

21. A switching power converter circuit comprising:

a first capacitor having first terminal and a second terminal;

a second capacitor having a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to first terminal of the first capacitor;

a bipolar transistor having a base, a collector, and an emitter, wherein the collector is coupled to the second terminal of the second capacitor, wherein the base is coupled to the second terminal of the first capacitor;

a diode having an anode and a cathode, wherein the anode is coupled to one of the collector and the emitter of the bipolar transistor, wherein the cathode is coupled to the other of the collector and the emitter of the bipolar transistor;

a first inductor having a first terminal and second terminal, wherein the first terminal of the first inductor is coupled to the collector of the bipolar transistor; and

a second inductor having a first terminal and second terminal, wherein the first terminal of the second inductor is coupled to the base of the bipolar transistor.

22. The switching power converter of claim 21, wherein the second terminal of the first inductor is coupled to the second terminal of the second inductor.

23. The switching power converter of claim 21, wherein the bipolar transistor is a PNP bipolar transistor, wherein the anode of the diode is coupled to the emitter of the bipolar transistor, and wherein the cathode of the diode is coupled to the collector of the bipolar transistor.

24. The switching power converter of claim 21, wherein the bipolar transistor is an NPN bipolar transistor, wherein the anode of the diode is coupled to the collector of the bipolar transistor, and wherein the cathode of the diode is coupled to the emitter of the bipolar transistor.