Control circuit, resonant converter and integrated circuit control chip

Patent metadata

Field	Value
Publication number	US-12132385-B2
Application number	US-202217868954-A
Country	US
Kind code	B2
Filing date	Jul 20, 2022
Priority date	Jul 21, 2021
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

A control circuit for a resonant converter, can include: a feedforward circuit configured to generate a feedforward current; a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode; and a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, where the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal.

First claim

What is claimed is:

1. A control circuit for a resonant converter, the control circuit comprising:
a) a feedforward circuit configured to generate a feedforward current;
b) a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode;
c) a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, wherein the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal; and
d) wherein a change tendency of the feedforward current is opposite to a change tendency of the error compensation signal, such that a value of the feedforward current increases as the required output power decreases.

2. The control circuit of claim 1 , wherein in the first mode, the feed-forward circuit does not generate the feed-forward current, and the control circuit is in a charge control mode to adjust the output power of the resonant converter by changing the input charge of the resonant converter, while a switching frequency of the resonant converter remains unchanged.

3. The control circuit of claim 1 , wherein in the second mode, the feed-forward circuit is enabled to generate the feedforward current, and the control circuit is in an equivalent frequency control mode to adjust the output power of the resonant converter by changing a switching frequency of the resonant converter.

4. The control circuit of claim 1 , wherein:
a) before the first threshold signal decreases to a minimum value, the control circuit operates in the first mode; and
b) after the first threshold signal reaches the minimum value, the control circuit operates in the second mode.

5. A resonant converter, comprising the control circuit of claim 1 , and further comprising:
a) a main power circuit comprising a first power transistor and a second power transistor connected in series between an input terminal and a reference ground;
b) a transformer comprising a primary winding and at least one secondary winding;
c) a resonant capacitor coupled in series with the primary winding to form a resonant unit; and
d) an output feedback circuit configured to integrate and compensate an error between the feedback signal and the reference signal, in order to generate the error compensation signal to transmit to the control circuit.

6. A control circuit for a resonant converter, the control circuit comprising:
a) a feedforward circuit configured to generate a feedforward current;
b) a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode;
c) a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, wherein the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal; and
d) a conversion circuit configured to receive an error current signal representing the error compensation signal transmitted from a secondary side of the resonant converter, and generate the first threshold signal according to a corresponding relationship.

7. The control circuit of claim 6 , wherein the conversion circuit is configured to generate the first threshold signal by a preset power curve according to the error current signal.

8. The control circuit of claim 6 , wherein the conversion circuit is configured to convert the error current signal into a voltage signal accordingly, and generate the first threshold signal by a preset power curve according to the voltage signal.

9. The control circuit of claim 6 , wherein the conversion circuit is configured to generate a compensation signal according to an error between the error current signal and the reference signal, and accordingly generate the first threshold signal by a preset power curve according to the compensation signal.

10. The control circuit of claim 6 , wherein:
a) when the error current signal is smaller than a first current, the first threshold signal remains unchanged;
b) when the error current signal is between the first current and a second current, the first threshold signal decreases as the error current signal increases, and the first threshold signal decreases to a minimum value when the error current signal reaches the second current; and
c) when the error current signal is greater than the second current, the first threshold signal is maintained at the minimum value.

11. The control circuit of claim 6 , wherein:
a) when the error current signal is greater than the second current, the feedforward current increases with the increase of the error current signal until reaching a maximum error current signal; and
b) the second current is a value of the error current signal at which the first threshold signal decreases to a minimum value.

12. A control circuit for a resonant converter, the control circuit comprising:
a) a feedforward circuit configured to generate a feedforward current;
b) a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode;
c) a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, wherein the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal; and
d) wherein the charge feedback circuit comprises a current sampling circuit configured to receive the resonant current sampling signal and convert to an integration current in the form of a current, and a current integration circuit configured to integrate the integration current and the feedforward current to generate the charge feedback signal.

13. The control circuit of claim 12 , wherein the current integration circuit is configured to integrate the integration current for half of a switching cycle in each switching cycle in the first mode, and to integrate the integration current and the feedforward current for half of the switching cycle in each switching cycle in the second mode.

14. The control circuit of claim 13 , wherein the current integration circuit is configured to generate the charge feedback signal across an integration capacitor by the integration current and the feedforward current during a first half of the switching cycle in the second mode, and the integration capacitor is controlled to discharge to zero duri

Assignees

• Silergy Semiconductor Technology Hangzhou Ltd

Inventors

• Chen Chaojun
• Deng Jian
• Jin Jin

Classifications

• H02M3/015

  with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit · CPC title

• H02M1/0045

  Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode · CPC title

• H02M1/0025 Primary

  Arrangements for modifying reference values, feedback values or error values in the control loop of a converter · CPC title

• Y02B70/10

  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 title

• H02M1/0035

  using burst mode control · CPC title