AC/DC converter including a bidirectional switch

• US 10,483,859 B2
• Filed: 11/08/2016
• Issued: 11/19/2019
• Est. Priority Date: 11/12/2015
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Hatano, Hiroyuki
• Primary Examiner(s): Zhang, Jue
• Assistant Examiner(s): Jackson, Lakaisha
• Application Number:
  US15/345,723
• Publication Number:
  US 20170141689A1
• Time in Patent Office: 1,106 Days
• CPC Class Codes: H02M 1/4241 using a resonant converter
• 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 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 3/33538 of the forward type H02M3/3353, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H02M 3/33553 with galvanic isolation between input and output of both the power stage and the feedback loop
• 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

An AC/DC converter includes a transformer including a primary winding connected to an AC power source and a secondary winding electromagnetically coupled to the primary winding, a bidirectional switch connected in series to the primary winding, a resonant capacitor connected in parallel or series to the bidirectional switch, a full-wave rectification circuit arranged to perform full-wave rectification of an induced voltage generated in the secondary winding, a smoothing capacitor arranged to smooth an output of the full-wave rectification circuit, and a control circuit arranged to turn on and off the bidirectional switch. The transformer is a leakage transformer or a resonant transformer having leakage inductance. The AC converter takes out both forward voltage and flyback voltage from the secondary winding, so as to directly convert an AC input voltage supplied from the AC power source into a DC output voltage.

Claims

1. An AC/DC converter comprising:

a transformer including a primary winding connected to an AC power source and a secondary winding electromagnetically coupled to the primary winding;

a bidirectional switch connected in series to the primary winding;

a resonant capacitor connected in parallel or series to the bidirectional switch;

a capacitor voltage divider circuit arranged to divide a voltage across both ends of the bidirectional switch so as to generate a divided voltage; and

a control circuit arranged to turn on the bidirectional switch at a timing when the divided voltage becomes zero.

2. The AC/DC converter according to claim 1, wherein the capacitor voltage divider circuit includes a first capacitor connected in series to the resonant capacitor, so that the divided voltage is output from a connection node between the resonant capacitor and the first capacitor.

3. The AC/DC converter according to claim 1, wherein the capacitor voltage divider circuit a first capacitor and a second capacitor connected in series to each other between both ends of the bidirectional switch, so that the divided voltage is output from a connection node between the first capacitor and the second capacitor.

4. The AC/DC converter according to claim 2, wherein the first capacitor has an end connected to a reference potential terminal of the control circuit.

5. The AC/DC converter according to claim 4, wherein the capacitor voltage divider circuit further includes a discharge switch connected in parallel to the first capacitor.

6. The AC/DC converter according to claim 5, wherein the control circuit turns on and off the discharge switch in synchronization with the bidirectional switch.

7. The AC/DC converter according to claim 1, wherein the transformer is a leakage transformer or a resonant transformer having leakage inductance, and the AC/DC converter takes out both forward voltage and flyback voltage from the secondary winding, so as to directly convert an AC input voltage supplied from the AC power source into a DC output voltage.

8. The AC/DC converter according to claim 1, further comprising a coil connected to at least one of the primary winding and the secondary winding, wherein the AC/DC converter takes out both forward voltage and flyback voltage from the secondary winding, so as to directly convert an AC input voltage supplied from the AC power source into a DC output voltage.

9. The AC/DC converter according to claim 1, wherein the control circuit drives the bidirectional switch so that power factor becomes close to one.

10. The AC/DC converter according to claim 1, wherein the control circuit drives the bidirectional switch via a pulse transformer.