Hysteretic control for transformer based power converters

• US 10,673,339 B2
• Filed: 03/18/2016
• Issued: 06/02/2020
• Est. Priority Date: 07/23/2015
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Seeman, Michael D.
• Primary Examiner(s): Ahmed, Yusef A
• Application Number:
  US15/073,964
• Publication Number:
  US 20170025961A1
• Time in Patent Office: 1,537 Days
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• 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 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• 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

Hysteretic control for power converters. In an example arrangement, an apparatus includes a converter for converting an input voltage to an output voltage including a transformer; at least one primary side driver switch coupled to supply current from an input voltage terminal to the primary side of the transformer; at least one inductor coupled between the secondary side of the transformer and the output voltage terminal; at least one secondary side switch coupled between the inductor and a ground potential; and a hysteretic controller coupled to supply a first on-time signal to the at least one primary side switch and a second on-time signal to the at least one secondary side switch, the hysteretic controller configured for sensing the output voltage and having at least one current input coupled for sensing current flowing in the inductor and generating primary side driver switch on-time pulses to control the output voltage.

Claims

1. An apparatus, comprising:

a power converter including;

a transformer having a primary side interfacing an input voltage terminal, and a secondary side interfacing an output voltage terminal;

a primary side switch coupled between the input voltage terminal and the primary side of the transformer;

an inductor having a first terminal coupled to the secondary side of the transformer, and a second terminal coupled the output voltage terminal;

a secondary side switch coupled between the first terminal of the inductor and a ground terminal; and

a hysteretic controller having;

a hysteretic comparator including a first input, a second input, and an output, the first input configured to receive a sensed current from the inductor, the second input configured to receive a differential voltage representing a potential difference between an output voltage at the output voltage terminal and a reference voltage;

a pulse sequencer coupled to the output of the hysteretic comparator; and

a dead-time generation circuit configured to provide a first on-time signal to the primary side switch and a second on-time signal to the secondary side switch based on a pulse signal received from the pulse sequencer.

2. The apparatus of claim 1, wherein the power converter comprises a half-bridge converter with a current doubler output.

3. The apparatus of claim 2, wherein the power converter comprises:

a second primary side switch coupled between the primary side of the transformer and a negative voltage input;

a second inductor having a first terminal coupled to the secondary side of the transformer, and a second terminal coupled to the output voltage terminal; and

a second secondary side switch coupled between the first terminal of the second inductor and the ground terminal;

wherein the dead-time generation circuit of the hysteretic controller is configured to provide third and fourth on-time signals to the second primary side switch and the second secondary side switch respectively.

4. The apparatus of claim 1, wherein the hysteretic controller includes a differential amplifier having a first input coupled to the output voltage terminal, a second input coupled to receive the reference voltage, and an output coupled to the hysteretic comparator to provide the differential voltage.

5. The apparatus of claim 1, wherein the first input terminal of the hysteretic comparator is configured as a negative input terminal, and the second input terminal of the hysteretic comparator is configured as a positive input terminal.

6. The apparatus of claim 1, wherein the hysteretic controller includes a compensation circuit coupled to the second input terminal of the hysteretic comparator.

7. The apparatus of claim 1, wherein the hysteretic controller includes a summing circuit coupled to the first input terminal of the hysteretic comparator to provide a summed current as the sensed current.

8. The apparatus of claim 1, wherein the primary side switch and the secondary side switch each includes a field effect transistors (FET).

9. The apparatus of claim 8, wherein the FET includes an enhancement mode FET.

10. The apparatus of claim 1, wherein the primary side switch and the secondary side switch each includes a gallium nitride (GaN) device.

11. The apparatus of claim 1, wherein the power converter comprises a full-bridge converter with a current doubler output.

12. The apparatus of claim 11, wherein the full-bridge converter comprises a second primary side switch coupled between the primary side of the transformer and a negative input voltage terminal, a third primary side switch coupled between the input voltage terminal and the primary side of the transformer, and a fourth primary side switch coupled between the primary side of the transformer and the negative input terminal.

13. The apparatus of claim 12, wherein the first, second, third, and fourth primary side switches each includes a gallium nitride (GaN) transistor.

14. A half-bridge transformer-based power converter;

comprising;

a transformer having a primary side with a first terminal and a second terminal and a secondary side with a third terminal and a fourth terminal;

a first primary side transistor coupled between a first voltage input terminal and the first terminal of the primary side of the transformer, and having a gate terminal;

a second primary side transistor coupled between a second voltage input terminal and the first terminal of the primary side of the transformer, and having a gate terminal;

a first secondary side transistor coupled between the third terminal of the secondary side of the transformer and a ground terminal, and having a gate terminal;

a second secondary side transistor coupled between the fourth terminal of the secondary side of the transformer and the ground terminal, and having a gate terminal;

a first inductor coupled between the third terminal of the secondary side of the transformer and an output voltage terminal;

a second inductor coupled between the fourth terminal of the secondary side of the transformer and the output voltage terminal; and

a hysteretic controller having;

a hysteretic comparator including a first input, a second input, and an output, the first input configured to receive a sensed current from the first and second inductors, the second input configured to receive a differential voltage representing a potential difference between an output voltage at the output voltage terminal and a reference voltage;

a pulse sequencer coupled to the output of the hysteretic comparator; and

a dead-time generation circuit configured to provide first, second, third, and fourth on-time signals to the first and second primary side transistors and the first and second secondary side transistors based on a pulse signal received from the pulse sequencer.

15. The half-bridge power converter of claim 14, wherein the hysteretic controller comprises a differential amplifier having a first input coupled to the output voltage terminal, a second input coupled to receive the reference voltage, and an output coupled to the hysteretic comparator to provide the differential voltage.

16. The half-bridge power converter of claim 14, wherein the hysteretic controller comprises a summer coupled to the first input terminal of the hysteretic comparator, the summer configured to add the sensed currents from the first and second inductors.

17. The half-bridge power converter of claim 14, wherein the first and second primary side transistors each comprises a gallium nitride (GaN) transistor.

18. The half-bridge power converter of claim 14, wherein the first and second primary side transistors each comprises a MOSFET.

19. The half-bridge power converter of claim 14, wherein the hysteretic controller includes a compensation circuit coupled to the second input terminal of the hysteretic comparator.

20. The half-bridge power converter of claim 14, further comprising:

a first capacitor coupled between the first voltage input terminal and the second terminal of the primary side of the transformer; and

a second capacitor coupled between the second voltage input terminal and the second terminal of the primary side of the transformer.