High-bandwith resonant power converters

• US 10,277,140 B2
• Filed: 08/31/2017
• Issued: 04/30/2019
• Est. Priority Date: 08/31/2017
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Jia, Liang, Lakshmikanthan, Srikanth
• Primary Examiner(s): Nguyen, Matthew V
• Application Number:
  US15/693,055
• Publication Number:
  US 20190068071A1
• Time in Patent Office: 607 Days
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• 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 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• 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

This specification describes a device that includes a voltage-regulated DC-DC converter comprising a switching network, a resonant circuit, and control circuitry, wherein the switching network has a switching frequency. The DC-DC converter has an output impedance and the control circuity uses a control loop to control the DC-DC converter. The control circuitry implements the control loop using: an output voltage sensor configured to sense an output voltage of the DC-DC converter; and a compensator configured to adjust operation of the DC-DC converter based on the output voltage sensed by the output voltage sensor. The DC-DC converter comprises an output impedance suppression mechanism configured to at least partially suppress increases in the output impedance of the DC-DC converter.

Claims

1. A device comprising:

a voltage-regulated DC-DC converter comprising a switching network, a resonant circuit, and control circuitry, wherein the switching network has a switching frequency, and wherein the voltage-regulated DC-DC converter has an output impedance;

wherein the control circuity uses a control loop to control the voltage-regulated DC-DC converter, the control circuitry implementing the control loop using;

an output voltage sensor configured to sense an output voltage of the voltage-regulated DC-DC converter; and

a compensator configured to adjust operation of the voltage-regulated DC-DC converter based on the output voltage sensed by the output voltage sensor; and

wherein the voltage-regulated DC-DC converter comprises an output impedance suppression mechanism configured to at least partially suppress increases in the output impedance of the voltage-regulated DC-DC converter.

2. The device of claim 1, wherein the output impedance suppression mechanism is configured to at least partially compensate for an output impedance spike occurring at the switching frequency.

3. The device of claim 1, wherein the output impedance suppression mechanism comprises a notch filter in the control loop, the notch filter being tuned for the switching frequency.

4. The device of claim 3, wherein the output impedance suppression mechanism comprises an operational amplifier and an impedance network that provide the notch filter for the control loop.

5. The device of claim 1, wherein the output impedance suppression mechanism comprises a zero-order hold mechanism.

6. The device of claim 5, wherein the zero-order hold mechanism is configured to operate at a sampling rate of about twice the switching frequency.

7. The device of claim 1, wherein the output impedance suppression mechanism comprises a decoupling network arranged in parallel with an output load of the voltage-regulated DC-DC converter, wherein the decoupling network has a resonant frequency within 10% of the switching frequency.

8. The device of claim 7, wherein the decoupling network comprises a capacitor having a self-resonant frequency within 10% of the switching frequency due to a capacitance of the capacitor and an equivalent series inductance of the capacitor.

9. The device of claim 1, wherein the resonant circuit is an LLC tank.

10. The device of claim 1, wherein the resonant circuit is an LC or LLCC resonant circuit.

11. The device of claim 1, wherein the compensator comprises a proportional-integral (PI) controller or a proportional-integral-derivative (PID) controller.

12. The device of claim 1, wherein the voltage-regulated DC-DC converter has a closed loop bandwidth that is about ⅓

of the switching frequency of the switching network and a phase margin of at least 45 degrees.

13. The device of claim 1, wherein the resonant circuit has a resonant frequency that is within 15% of the switching frequency of the switching network.

14. The device of claim 1, wherein the control circuitry for the voltage-regulated DC-DC converter implements charge control that controls switching of the switching network components based on a voltage of a capacitor of the resonant circuit.

15. The device of claim 1, wherein the control circuitry controls the switching network to output a pulsed output to the resonant circuit;

wherein the resonant circuit is an LLC tank;

wherein the capacitor is a capacitor of the LLC tank; and

wherein the control circuitry is configured such that, at switching times for MOSFETs in the voltage-regulated DC-DC converter, the voltage of the capacitor directly controls per-cycle input charge to the capacitor.

16. The device of claim 1, wherein the switching network comprises a switching rectifier operating at the switching frequency.

17. The device of claim 1, wherein the output impedance suppression mechanism is configured to at least partially suppress frequency-related increases in the output impedance of the voltage-regulated DC-DC converter.

18. The device of claim 1, wherein the output impedance suppression mechanism is configured to suppress increases in the output impedance of the voltage-regulated DC-DC that occur as changes in load demands approach the switching frequency of the switching network.

19. A device comprising:

a voltage-regulated DC-DC converter comprising;

a pulse-generating circuit configured to receive a DC input and provide a pulsed output;

an LLC tank coupled to receive the pulsed output;

a transformer having a primary coil and a secondary coil, the transformer being coupled to receive a signal from the LLC tank at the primary coil and output a signal at the secondary coil;

a switching rectifier having a switching frequency, configured to convert the signal output at the secondary coil to a DC voltage;

control circuitry configured to regulate the voltage output of the voltage-regulated DC-DC converter, wherein the control circuitry uses a voltage-mode feedback control loop using;

an output voltage sensor configured to sense an output voltage of the voltage-regulated DC-DC converter; and

a compensator configured to adjust operation of the voltage-regulated DC-DC converter based on the output voltage sensed by the output voltage sensor;

wherein the voltage-regulated DC-DC converter comprises an output impedance suppression mechanism configured to at least partially suppress increases in the output impedance of the voltage-regulated DC-DC converter.

20. The device of claim 19, wherein the pulse-generating circuit comprises a half-bridge or full-bridge configuration of MOSFETs configured to generate a pulsed output in response to control signals from the control circuitry,

wherein the control circuitry uses the voltage-mode feedback control loop to adjust parameters that drive the MOSFETs of the pulse-generating circuit.

21. The device of claim 19, wherein the output impedance suppression mechanism is configured to at least partially compensate for an output impedance spike occurring at the switching frequency.

22. A method comprising:

receiving a DC input to a voltage-regulated DC-DC converter comprising a switching network, a resonant circuit, and control circuitry, wherein the switching network has a switching frequency, and wherein the voltage-regulated DC-DC converter has an output impedance;

regulating voltage output of the voltage-regulated DC-DC converter using a control loop by sensing an output voltage of the voltage-regulated DC-DC converter and adjusting operation of the voltage-regulated DC-DC converter based on the output voltage sensed by the output voltage sensor; and

using an output impedance suppression mechanism to at least partially suppress increases in the output impedance of the voltage-regulated DC-DC converter.