CN117767765A

CN117767765A - Resonant circuit, charging control method and charger

Info

Publication number: CN117767765A
Application number: CN202410114949.8A
Authority: CN
Inventors: 薛瑞普; 王晓洋; 周海滨; 王亚彪; 彭祥敏
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2024-01-29
Filing date: 2024-01-29
Publication date: 2024-03-26
Anticipated expiration: 2044-01-29
Also published as: CN117767765B

Abstract

The embodiment of the application provides a resonant circuit, a charging control method and a charger, wherein the circuit comprises a DC-DC primary side module and a DC-DC secondary side module; the DC-DC secondary side module comprises a first secondary side vibration sub-module, a second secondary side vibration sub-module and a second change-over switch sub-module; under the condition that the second change-over switch submodule is conducted, the first side oscillation submodule and the second side oscillation submodule are in an enabling state, and the resonant circuit works in a PFM mode; under the condition that the second change-over switch submodule is disconnected, the second side oscillation submodule is in an enabling state, and the resonant circuit works in a PWM mode. The second change-over switch sub-module is used for controlling the enabling of the first side-vibration sub-module, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized, and the charging can be performed by adopting the PWM mode when the charging gain or the output power is smaller, so that the loss of a charging system when the load is lighter is reduced.

Description

Resonant circuit, charging control method and charger

Technical Field

The present disclosure relates to the field of electronic technologies, and in particular, to a resonant circuit, a charging control method, and a charger.

Background

Along with the development of mobile terminal technology, various wearable devices compete, so that the production and the life of people become more convenient. The fast charging technology is one of the key technology competition points in the mobile terminal industry, and is attracting more and more attention. The current mainstream fast charging protocols include PD (power release), QC (Quick Charge), UFCS (Universal Fast Charging Specification, universal fast charging standard), and the like, which all have specific index requirements on the fast charging technology: the output voltage of the charger is continuously adjustable.

The fast charging type charger has the characteristics of high efficiency, high power, small volume and the like. The current mainstream technology is still concentrated on flyback and flyback deformation topologies, the conversion efficiency is low, the expansibility of output power is poor, the future technical development cannot be further supported, and the new topology adaptability is researched into the future development direction; the LLC circuit is a resonant circuit formed by 2 inductors and 1 capacitor, so the LLC circuit is called LLC, the LLC circuit has 50% fixed duty ratio, the transformer works in 1 quadrant and 3 quadrant, the utilization rate of magnetic materials is improved by 1 time, the device stress is low, the loss is small, and the like, and the LLC circuit gradually becomes the development direction of the quick charging technology.

In the related art, LLC circuits are powered by PFM (Pulse Frequency Modulation ) mode, the power is changed by changing the pulse frequency, the charging gain of PFM is nonlinear, the lighter the load is, the smaller the charging gain is needed, and the higher the switching frequency is, so that when the load is lighter, the larger the loss of the charging system is caused.

Disclosure of Invention

An objective of the embodiments of the present application is to provide a resonant circuit, a charging control method, and a charger, so as to reduce loss of a charging system in an LLC circuit. The specific technical scheme is as follows:

according to a first aspect of embodiments of the present application, there is provided a resonant circuit comprising:

DC-DC primary side module and DC-DC secondary side module;

the DC-DC secondary side module comprises a first secondary side vibration sub-module, a second secondary side vibration sub-module and a second change-over switch sub-module; the first side oscillation submodule is respectively connected with the second side oscillation submodule and the second change-over switch submodule;

under the condition that the second change-over switch submodule is conducted, the first side oscillation submodule and the second side oscillation submodule are in an enabling state, and the resonant circuit works in a PFM mode;

And under the condition that the second change-over switch submodule is disconnected, the second side oscillation submodule is in an enabling state, and the resonant circuit works in a PWM mode.

In the embodiment of the application, the second change-over switch sub-module is used for controlling the enabling of the first side-vibration sub-module, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized, and the charging can be performed by adopting the PWM mode when the charging gain or the output power is smaller, so that the loss of the charging system when the load is lighter is reduced.

In one possible implementation, the DC-DC primary side module includes a first primary side oscillator sub-module, a second primary side oscillator sub-module, and a first switch sub-module; the first primary side oscillation submodule is respectively connected with the second primary side oscillation submodule and the first switching submodule; the second primary side vibration oscillator sub-module is connected with the first switch sub-module;

when the first change-over switch sub-module is disconnected and the second change-over switch sub-module is conducted, the first primary side oscillation sub-module, the first secondary side oscillation sub-module and the second secondary side oscillation sub-module are in an enabling state, and the resonant circuit works in a PFM mode;

And under the condition that the first change-over switch sub-module is conducted and the second change-over switch sub-module is disconnected, the first primary side vibration sub-module, the second primary side vibration sub-module and the second secondary side vibration sub-module are in an enabling state, and the resonant circuit works in a PWM mode.

In the embodiment of the application, the first switch sub-module is used for controlling the enabling of the second primary side oscillation sub-module, and the second switch sub-module is used for controlling the enabling of the first side oscillation sub-module, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized, and the charging can be performed by adopting the PWM mode when the charging gain or the output power is smaller, so that the loss of the charging system when the load is lighter is reduced.

In one possible implementation manner, the first primary oscillation submodule includes a first capacitor, a first transistor, a second capacitor, a third capacitor, a first inductor, a third inductor and a fifth capacitor;

the first end of the fifth capacitor is respectively connected with the first end of the first transistor and the first end of the capacitor; the second end of the fifth capacitor is respectively connected with the second end of the second transistor, the second end of the second capacitor and the second end of the third capacitor;

The second end of the first transistor is respectively connected with the second end of the first capacitor, the first end of the first inductor, the first end of the second transistor and the first end of the second capacitor;

the second end of the first inductor is connected with the first end of the third inductor, and the second end of the third inductor is connected with the first end of the third capacitor.

In the embodiment of the application, a specific circuit structure of the first primary side oscillation submodule is provided, so that the switching of the DC-DC primary side module between a PFM driving mode and a PWM driving mode is realized, and the switching of the resonant circuit between the PFM mode and the PWM mode is realized.

In a possible implementation manner, the second primary side oscillator sub-module comprises a fourth capacitor and a second inductor, and the first switch sub-module comprises a first switch and a second switch;

the first end of the second inductor is connected with the first end of the first inductor, the second end of the second inductor is connected with the first end of the first switch, and the second end of the first switch is connected with the first end of the third inductor;

the first end of the fourth capacitor is connected with the first end of the second switch, the second end of the fourth capacitor is connected with the second end of the third capacitor, and the second end of the second switch is connected with the first end of the third capacitor.

In the embodiment of the application, a specific circuit structure of the second primary side vibration oscillator sub-module and the first switching switch sub-module is provided, so that the switching of the DC-DC primary side module between the PFM driving mode and the PWM driving mode is realized, and the switching of the resonant circuit between the PFM mode and the PWM mode is realized.

In one possible implementation manner, the second side oscillation submodule includes a fifth inductor, a fourth transistor and a sixth capacitor,

the first end of the fifth inductor is connected with the first end of the sixth capacitor, the second end of the fifth inductor is connected with the first end of the fourth transistor, and the second end of the fourth transistor is connected with the second end of the sixth capacitor.

In the embodiment of the application, a specific circuit structure of the second side-vibration sub-module is provided, and the switching of the DC-DC side module between the PFM driving mode and the PWM driving mode is realized, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized.

In a possible implementation manner, the first side oscillation submodule comprises a fourth inductor and a third transistor, and the second change-over switch submodule comprises a fifth transistor;

the first end of the fourth inductor is connected with the first end of the fifth transistor, and the second end of the fourth inductor is connected with the first end of the sixth capacitor;

The second end of the fifth transistor is connected with the first end of the third transistor, and the second end of the third transistor is connected with the second end of the sixth capacitor.

In the embodiment of the application, specific circuit structures of the first side-vibration sub-module and the second change-over switch sub-module are provided, and the switching of the DC-DC side-module between the PFM driving mode and the PWM driving mode is realized, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized.

In one possible embodiment, the third transistor is replaced with a first diode, the fourth transistor is replaced with a second diode, and/or the fifth transistor is replaced with a third switch.

In the embodiment of the application, a specific circuit structure of the DC-DC secondary side module is provided, and the switching of the DC-DC secondary side module between a PFM driving mode and a PWM driving mode is realized, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized.

In one possible implementation, the circuit further includes: an isolation module;

the DC-DC primary side module further comprises a primary side switching control sub-module, and the DC-DC secondary side module comprises a secondary side switching control sub-module;

The isolation module is respectively connected with the primary side switching control submodule and the secondary side switching control submodule;

the primary side switching control sub-module is used for controlling the disconnection and connection of the first switching sub-module;

the secondary side switching control sub-module is used for controlling the disconnection and connection of the second switching sub-module;

and the isolation module is used for realizing signal isolation transmission between the primary side switching control sub-module and the secondary side switching control sub-module.

In the embodiment of the application, the signal isolation transmission between the DC-DC primary side module and the DC-DC secondary side module is realized, so that the DC-DC primary side module and the DC-DC secondary side module can communicate in a signal isolation transmission mode, the electrical safety between the primary side and the secondary side is ensured, and the switching between the PFM mode and the PWM mode can be realized in a coordinated mode.

According to a second aspect of embodiments of the present application, there is provided a charge control method, the method including:

acquiring a current charging gain;

and under the condition that the current charging mode is the PFM mode, if the current charging gain is smaller than a preset second gain threshold value and/or the current output power is not larger than a preset power threshold value, switching the charging mode into the PWM mode.

In the embodiment of the application, when the charging gain or the output power is smaller, the charging mode is switched from the PFM mode to the PWM mode, and the charging loss of the PWM mode is lower than that of the PFM mode under the condition of low load, so that the loss of the charging system when the load is lighter can be reduced.

In one possible embodiment, the method further comprises:

judging whether the current charging gain is larger than a preset first gain threshold value or not; wherein the preset second gain threshold is less than the preset first gain threshold;

and under the condition that the current charging mode is the PFM mode and the current charging gain is larger than a preset first gain threshold value, switching the charging mode into the PWM mode.

When the gain of the charging system is larger than the maximum gain of the LLC circuit, the LLC circuit enters a capacitive area in the PFM mode and cannot work normally, and in this case, the charging can be performed in the PFM mode so as to expand the chargeable gain interval.

In one possible embodiment, the method further comprises:

judging whether the current charging gain is smaller than a preset second gain threshold value or not under the condition that the current charging gain is not larger than the preset first gain threshold value;

and under the condition that the current charging mode is the PFM mode, if the current charging gain is not smaller than a preset second gain threshold value and the current output power is larger than a preset power threshold value, maintaining the charging mode as the PFM mode.

In this embodiment of the present application, when the current charging gain is not less than the preset second gain threshold, and the current output power is greater than the preset power threshold, the charging mode is maintained to be the PFM mode, and the higher charging power can be maintained.

In one possible embodiment, the method further comprises:

judging whether the current charging gain is smaller than a preset second gain threshold value or not under the condition that the current charging mode is a PWM mode and the current charging gain is not larger than the preset first gain threshold value, wherein the preset second gain threshold value is smaller than the preset first gain threshold value;

under the condition that the current charging gain is not smaller than a preset second gain threshold value, acquiring current output power, and judging whether the current output power is larger than a preset power threshold value or not;

if the current output power is larger than the preset power threshold, switching the charging mode to a PFM mode;

and if the current output power is not greater than the preset power threshold, maintaining the charging mode as the PWM mode.

In the embodiment of the application, the situation that the PWM mode is switched to the PFM mode is given, and when the charging gain is not smaller than the preset second gain threshold and the output power is larger than the preset power threshold, the charging mode is switched to the PFM mode from the PWM mode, so that the charging efficiency can be improved, and the loss is reduced.

In one possible implementation, after the step of obtaining the current charging gain, the method further includes:

judging whether the current charging gain is the same as the last charging gain;

if the current charging gain is the same, discarding the current charging gain, and waiting for the next detection period.

In the embodiment of the application, when the charging gain of the current detection period is unchanged, the adjustment of the charging mode is not needed, so that the current charging gain is discarded without a subsequent judgment process in the period, and the next detection period is waited for reacquiring; thus, unnecessary judging processes can be reduced, and computing resources can be saved.

According to a third aspect of embodiments of the present application, there is provided a charger, including any of the resonant circuits and a charge control chip described in the present application; the charging control chip is used for controlling the resonant circuit to switch the charging mode through any one of the charging control methods in the application when the charging control chip is in operation.

The embodiment of the application provides a resonance circuit, a charging control method and a charger, wherein the resonance circuit comprises a DC-DC primary side module and a DC-DC secondary side module; the DC-DC secondary side module comprises a first secondary side vibration sub-module, a second secondary side vibration sub-module and a second change-over switch sub-module; the first side oscillation submodule is respectively connected with the second side oscillation submodule and the second change-over switch submodule; under the condition that the second change-over switch submodule is conducted, the first side oscillation submodule and the second side oscillation submodule are in an enabling state, and the resonant circuit works in a PFM mode; under the condition that the second change-over switch submodule is disconnected, the second side oscillation submodule is in an enabling state, and the resonant circuit works in a PWM mode. The second change-over switch sub-module is used for controlling the enabling of the first side-vibration sub-module, so that the switching of the resonant circuit between the PFM mode and the PWM mode is realized, and the charging can be performed by adopting the PWM mode when the charging gain or the output power is smaller, so that the loss of a charging system when the load is lighter is reduced.

Of course, not all of the above-described advantages need be achieved simultaneously in practicing any one of the products or methods of the present application.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following description will briefly introduce the drawings that are required to be used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other embodiments may also be obtained according to these drawings to those skilled in the art.

FIG. 1 is a schematic diagram of a prior art resonant circuit;

FIG. 2 is a first schematic diagram of a resonant circuit provided in an embodiment of the present application;

FIG. 3 is a second schematic diagram of a resonant circuit provided in an embodiment of the present application;

FIG. 4 is a third schematic diagram of a resonant circuit provided by an embodiment of the present application;

FIG. 5 is a fourth schematic diagram of a resonant circuit provided by an embodiment of the present application;

FIG. 6 is a fifth schematic diagram of a resonant circuit provided by an embodiment of the present application;

fig. 7 is a first schematic diagram of a charge control method according to an embodiment of the present application;

fig. 8 is a second schematic diagram of a charge control method according to an embodiment of the present application;

FIG. 9 is a schematic diagram of a resonant circuit in PFM mode in an embodiment of the present application;

FIG. 10 is a waveform diagram of key points in a resonant circuit in PFM mode in an embodiment of the present application;

FIG. 11 is a schematic diagram of a resonant circuit in PWM mode in an embodiment of the present application;

fig. 12 is a waveform diagram of each critical point in the resonant circuit in PWM mode according to the embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. Based on the embodiments herein, a person of ordinary skill in the art would be able to obtain all other embodiments based on the disclosure herein, which are within the scope of the disclosure herein.

The LLC circuit is a resonant circuit composed of 2 inductors and 1 capacitor, and is called LLC. The topology can be classified as half-bridge or full-bridge depending on the arrangement of transistors (e.g., MOS transistors). The LLC circuit can realize soft switching of a transistor through resonance, reduces switching loss, realizes ZVS (Zero Voltage Switch, zero voltage switching) of a primary side switching tube in a full power range, realizes ZCS (Zero Current Switch, zero current switching) of an SR (synchronous rectifier) switching tube, and has low device stress and small loss; the leakage inductance of the transformer participates in the resonant circuit, and the leakage inductance energy is transmitted to Vbus (power supply pin) and the secondary side through resonance, so that the energy loss is small. In addition, the on-state loss of the transistor is low, namely, the generated Joule heat is small, so that a radiating fin is not additionally used for radiating. Because of these advantages, LLC circuits are increasingly becoming a development of fast-charging technology.

In the related art, LLC circuits are all powered by PFM (Pulse Frequency Modulation ) mode, and the circuit diagram is shown in fig. 1, wherein Vin represents a power input terminal, vout represents a power output terminal, MA, MB, MC, MD is a MOS transistor, LA, LB, LC, LD is an inductor, and CA and CB are capacitors. PFM is an analog signal modulation scheme that varies the magnitude of power by varying the pulse frequency. The charging gain of the PFM is nonlinear, the lighter the load is, the smaller the charging gain is required, and the higher the switching frequency is, so that the larger the loss of the charging system is caused when the load is lighter.

In view of this, embodiments of the present application provide a resonant circuit, including: DC-DC primary side module and DC-DC secondary side module;

In one possible implementation manner, the resonant circuit in the embodiment of the present application may be as shown in fig. 2, and includes:

a DC-DC primary side module 01 and a DC-DC secondary side module 02;

the DC-DC primary side module 01 comprises a first primary side vibration and oscillation submodule 011, a second primary side vibration and oscillation submodule 012 and a first switch submodule 013; the first primary side oscillating sub-module 011 is respectively connected with the second primary side oscillating sub-module 012 and the first switching sub-module 013; the second primary side oscillator submodule 012 is connected with the first switch submodule 013;

the DC-DC secondary side module 02 comprises a first secondary side vibration oscillator sub-module 021, a second secondary side vibration oscillator sub-module 022 and a second change-over switch sub-module 023; the first side oscillation submodule 021 is respectively connected with the second side oscillation submodule 022 and the second change-over switch submodule 023;

Wherein, when the first switch sub-module 013 is turned off and the second switch sub-module 023 is turned on, the first primary side oscillation sub-module 011, the first secondary side oscillation sub-module 021 and the second secondary side oscillation sub-module 022 are in an enabled state, the resonant circuit works in a PFM mode,

when the first switch sub-module 013 is turned on and the second switch sub-module 023 is turned off, the first primary side oscillator sub-module 011, the second primary side oscillator sub-module 012, and the second secondary side oscillator sub-module 022 are in an enabled state, and the resonant circuit operates in a PWM (Pulse width modulation ) mode.

The PWM mode realizes the adjustment of power by changing the pulse time width; when the load is lighter, the switching frequency is unchanged, and the load is lightened by reducing the pulse width, so that compared with the PFM mode, the loss of a charging system can be reduced, and the charging efficiency is improved.

The first switch sub-module 013 is used for controlling the enabling of the second primary side oscillator sub-module 012, and when the first switch sub-module 013 is conducted, the second primary side oscillator sub-module 012 works; when the first switch sub-module 013 is open, the second primary side oscillator sub-module 012 is inactive. For the DC-DC primary module 01, when the first primary oscillating sub-module 011 and the second primary oscillating sub-module 012 both work, the DC-DC primary module 01 is in PWM driving mode; when the first primary side oscillator submodule 011 works and the second primary side oscillator submodule 012 does not work, the DC-DC primary side module 01 is in a PFM driving mode.

The second switch sub-module 023 is used for controlling the enabling of the first side oscillation sub-module 021, and when the second switch sub-module 023 is conducted, the first side oscillation sub-module 021 works; when the second change-over switch sub-module 023 is disconnected, the first side oscillation sub-module 021 does not work. For the DC-DC secondary side module 02, when the first secondary side oscillation submodule 021 and the second secondary side oscillation submodule 022 work, the DC-DC secondary side module 02 adopts a PFM driving mode; when the second side oscillation submodule 022 works and the first side oscillation submodule 021 does not work, the DC-DC side module 02 is in a PWM driving mode.

In the embodiment of the application, the first switching sub-module is used for controlling the enabling of the second primary side oscillating sub-module, so that the DC-DC primary side module can be suitable for the frequency in the PWM mode; and controlling the enabling of the first side-shaking sub-module by using the second change-over switch sub-module, so that the switching of the resonant circuit between the PFM mode and the PWM mode can be realized, and the charging can be performed by adopting the PWM mode when the charging gain or the output power is smaller, thereby reducing the loss of the charging system when the load is lighter.

In one possible implementation manner, referring to fig. 3, the first primary oscillating submodule includes a first capacitor C1, a first transistor M1, a second transistor M2, a second capacitor C2, a third capacitor C3, a first inductor L1, a third inductor L3, and a fifth capacitor C5;

The first end of the fifth capacitor C5 is connected to the first end of the first transistor M1 and the first end of the capacitor C1, respectively; the second end of the fifth capacitor C5 is connected to the second end of the second transistor M2, the second end of the second capacitor C2, and the second end of the third capacitor C3, respectively;

the second end of the first transistor M1 is connected to the second end of the first capacitor C1, the first end of the first inductor L1, the first end of the second transistor M2, and the first end of the second capacitor C2, respectively;

the second end of the first inductor L1 is connected to the first end of the third inductor L3, and the second end of the third inductor L3 is connected to the first end of the third capacitor C3.

The second primary side vibration submodule is respectively connected with the first end of the first inductor L1 and the second end of the second capacitor, and the first switch submodule is respectively connected with the first end of the third inductor L3 and the first end of the third capacitor C3.

In a possible implementation manner, the second primary side oscillator sub-module includes a fourth capacitor C4 and a second inductor L2, and the first switch sub-module includes a first switch S1 and a second switch S2;

the first end of the second inductor L2 is connected with the first end of the first inductor L1, the second end of the second inductor L2 is connected with the first end of the first switch S1, and the second end of the first switch S1 is connected with the first end of the third inductor L3;

The first end of the fourth capacitor C4 is connected to the first end of the second switch S2, the second end of the fourth capacitor C4 is connected to the second end of the third capacitor C3, and the second end of the second switch S2 is connected to the first end of the third capacitor C3.

In a possible implementation manner, the second side oscillation submodule includes a fifth inductance L5, a fourth transistor M4 and a sixth capacitance C6;

the first end of the fifth inductor L5 is connected to the first end of the sixth capacitor C6, the second end of the fifth inductor L5 is connected to the first end of the fourth transistor M4, and the second end of the fourth transistor M4 is connected to the second end of the sixth capacitor C6.

The first secondary oscillation submodule is respectively connected with a first end and a second end of the sixth capacitor C6. In a possible implementation manner, the first side oscillation submodule includes a fourth inductance L4 and a third transistor M3, and the second change-over switch submodule includes a fifth transistor M5;

a first end of the fourth inductor L4 is connected to the first end of the fifth transistor M5, and a second end of the fourth inductor L4 is connected to the first end of the sixth capacitor C6;

a second terminal of the fifth transistor M5 is connected to the first terminal of the third transistor M3, and a second terminal of the third transistor M3 is connected to the second terminal of the sixth capacitor C6.

It is understood that the capacitor has no polarity division, and the first end of the capacitor and the second end of the capacitor in the embodiment of the present application are only used to distinguish the two ends of the capacitor. Similarly, in the embodiment of the present application, the first end of the inductor and the second end of the inductor are only used to distinguish the two ends of the inductor, and the first end of the switch and the second end of the switch are also only used to distinguish the two ends of the switch. The first end of the transistor may be a source of the transistor, and the second end of the corresponding transistor may be a drain of the transistor; the first end of the transistor may be the drain of the transistor, and the corresponding second end of the transistor may be the source of the transistor; the setting can be specifically performed according to actual situations, and the specific limitation is not made in the present application.

It will be appreciated that the fifth transistor is a switching action, and in some examples it may be replaced by a third switch S3. The third and fourth transistors are mainly used to prevent current from flowing backward, and thus, in some examples, the third transistor may be replaced with the first diode D1 and/or the fourth transistor may be replaced with the second diode D2. The cathode of the first diode is directly or indirectly connected to the cathode of the second diode Vout (power output terminal), for example, as shown in fig. 4, and the cathode of the first diode is indirectly connected to the cathode of the second diode Vout, for example, as shown in fig. 5, through a fifth transistor Vout.

In the embodiment of the application, specific circuit structures of the DC-DC primary side module and the DC-DC secondary side module are provided, and switching of the resonant circuit between the PFM mode and the PWM mode is realized, so that when the charging gain or the output power is smaller, the charging can be performed by adopting the PWM mode, and the loss of a charging system when the load is lighter is reduced.

In one possible implementation, referring to fig. 6, the circuit further includes: an isolation module 03;

the DC-DC primary module 01 further includes a primary switching control sub-module 014, and the DC-DC secondary module 02 includes a secondary switching control sub-module 024;

the isolation module 03 is connected with the primary side switching control sub-module 014 and the secondary side switching control sub-module 024 respectively;

the primary side switching control sub-module 014 is configured to control the first switching switch sub-module 013 to be turned off and on;

the secondary side switching control sub-module 024 is configured to control the second switching sub-module 023 to be turned off and turned on;

the isolation module 03 is configured to implement signal isolation transmission between the primary side switching control sub-module 014 and the secondary side switching control sub-module 024.

In one example, the resonant circuit is initially operated in a PWM mode, or the resonant circuit is first charged in the PWM mode after power up.

In order to realize switching between the PFM mode and the PWM mode, signals need to be communicated between the DC-DC primary side module and the DC-DC secondary side module so as to realize switching of respective driving modes of the DC-DC primary side module and the DC-DC secondary side module. In order to realize the electrical isolation of the DC-DC primary side module and the DC-DC secondary side module, the isolation module can be utilized to realize the signal isolation transmission between the DC-DC primary side module and the DC-DC secondary side module. The isolation module in the embodiment of the application can realize information isolation transmission by adopting a transformer carrier mode; or, the primary side and the secondary side realize information isolation transmission through a capacitance isolation scheme; or, the primary side and the secondary side realize signal isolation transmission through an optical coupler; or the primary side and the secondary side realize signal isolation transmission through a magnetic isolation scheme and the like, which are all within the protection scope of the application.

Hereinafter, the working process of the resonant circuit in the PFM mode and the PWM mode in the embodiment of the present application will be specifically described, and in the PFM mode, a schematic diagram of the resonant circuit is shown in fig. 9, and key point waveforms thereof are shown in fig. 10. Where Vg1 is the voltage at the control terminal (gate) of the first transistor M1, vg2 is the voltage at the control terminal (gate) of the second transistor M2, ip is the primary resonance current (current of the first inductor L1), VA is the voltage at the second terminal of the first transistor M1, ID1 is the current of the third transistor, and ID2 is the current of the fourth transistor.

In the PWM mode, the schematic diagram of the resonant circuit is shown in fig. 11, and the key point waveforms are shown in fig. 12. Where Vg1 is the voltage at the control terminal (gate) of the first transistor M1, vg2 is the voltage at the control terminal (gate) of the second transistor M2, ip is the primary resonance current (the sum of the currents of the first inductor L1 and the second inductor L2), and Id is the current of the fourth transistor.

It can be seen that the resonant circuit in the embodiments of the present application can realize charging in PFM mode and PWM mode. In addition, in the PFM mode and the PWM mode, it is necessary to ensure that the transformer transformation ratio N is uniform, so that stability of the output voltage is ensured when the PFM mode and the PWM mode are switched.

Wherein, under the PWM mode:

D=N2×Vo/（N1×Vin）×（Lm+Lr）/Lm≈N2×Vo/（N1×Vin）（1）

Vcr=N× Vo （2）

(Vin- Vcr)×D=N× Vo×（1-D）（3）

where D is the duty cycle, N1 is the primary transformer turns, N2 is the secondary transformer turns, vo is the secondary output voltage, vin is the primary input voltage, lm is the primary transformer inductance, lr is the primary resonant inductance, n=n1/N2, vcr is the voltage of the transistor shunt capacitance in the primary (e.g., voltage of C1 in fig. 11).

Since Lm is much larger than Lr, equation 1 can be modified as:

D=N2×Vo/（N1×Vin）×（Lm+Lr）/Lm≈N2×Vo/（N1×Vin）（4）

from formulas (2) - (4):

Kv= Vo/ Vin=D/N （5）

wherein Kv is the charging gain.

When Vin is 380V, d=0.5, vo=20v, the transformer transformation ratio n=380V/20v×0.5=9.5.

In the PFM mode, when the LLC circuit works at a resonant frequency point, the charging gain is 1, the LLC circuit is in a half-bridge topology, and the transformer is shown in the following formula:

N=Vin/2/Vo （6）

when vin=380v, vo=20v, the transformer ratio n=9.5.

It can be seen that the transformer transformation ratio N is identical and the output voltage is stable when the PFM mode and the PWM mode are switched.

The following describes a switching method between the PFM mode and the PWM mode, referring to fig. 7, an embodiment of the present application provides a charging control method, which includes:

s101, acquiring current charging gain;

the method for obtaining the charging gain can refer to the prior art, for example, the ratio of the primary inductor coil to the secondary inductor coil can be calculated to obtain the charging gain; or calculating the ratio of the input voltage to the output voltage to obtain the charging gain and the like.

S102, if the current charging mode is the PFM mode, and/or the current output power is not greater than the preset power threshold value, switching the charging mode to the PWM mode.

The second gain threshold may be obtained according to an experimental measurement, for example, for a charging system, the charging system losses of the PFM mode and the PWM mode under different gains are experimentally measured in advance, so as to obtain the second gain threshold. Wherein the second gain threshold satisfies: when the charging gain of the charging system is smaller than the second gain threshold, the loss of the charging system in the PFM mode is larger than the loss of the charging system in the PWM mode, and when the charging gain of the charging system is larger than the second gain threshold, the loss of the charging system in the PFM mode is smaller than the loss of the charging system in the PWM mode.

In one example, the second gain threshold may be set to 0.8, i.e., when the current charging gain is less than 0.8, the hardware circuit is adjusted to enter a PWM mode, and ZVS may be implemented in the PWM mode as well, so as to obtain relatively high charging efficiency.

The preset power threshold may be obtained according to an experimental measurement, for example, for a charging system, the losses of the charging systems in PFM mode and PWM mode under different powers are experimentally measured in advance, so as to obtain the preset power threshold. Wherein, preset power threshold satisfies: when the power of the charging system is smaller than a preset power threshold, the loss of the charging system in the PFM mode is larger than the loss of the charging system in the PWM mode, and when the power of the charging system is larger than the preset power threshold, the loss of the charging system in the PFM mode is smaller than the loss of the charging system in the PWM mode. Alternatively, the preset power threshold may be an empirical value, where it is considered that when the power of the charging system is less than the preset power threshold, the charging efficiency is low, the loss is high, and the charging efficiency is not acceptable.

The output power may be obtained by referring to an output power calculation method in the prior art, in an example, the output power may be obtained by calculating according to an output voltage and an output current of an output side (secondary side), and the method for obtaining the output power is not specifically limited in this application.

In one example, power is initially supplied in a PWM mode, or the charger is first charged in the PWM mode after power is up.

In one possible embodiment, the method further comprises:

When the gain of the charging system is larger than the maximum gain of the LLC circuit, the LLC circuit enters a capacitive area in the PFM mode and cannot work normally, and in this case, the charging can be performed in the PFM mode so as to expand the chargeable gain interval. The preset first gain threshold may be obtained according to experimental measurement, and may be determined according to the gain of the LLC circuit entering the capacitive region in PFM mode. For example, for each model of LLC circuit, in PFM mode, when the boost charge benefit is X, the LLC circuit enters the capacitive region, and the preset first gain threshold may be X or slightly less than X.

In one possible embodiment, the method further comprises:

under the condition that the current charging gain is smaller than a preset second gain threshold value, maintaining the charging mode as a PWM mode; under the condition that the current charging gain is not smaller than a preset second gain threshold value, acquiring current output power, and judging whether the current output power is larger than a preset power threshold value or not;

acquiring input voltage and output voltage of a resonance circuit in the current period;

when at least one of the input voltage and the output voltage of the current period is changed compared with the previous period, executing the steps of: acquiring a current charging gain; otherwise, waiting for the next detection period.

The real-time charging gain can be periodically obtained according to a preset detection period. Firstly, acquiring the input voltage of the primary side and the output voltage of the secondary side of a resonant circuit in the current period; compared with the previous cycle, if at least one of the input voltage and the output voltage of the present cycle changes, step S101 is executed, otherwise the present cycle is skipped, and the next detection cycle is waited for to judge again. If the input voltage and the output voltage are both changed, it indicates that the charging gain is not changed, that is, the charging condition of the current period is not changed or is changed little compared with the charging condition of the previous period. Therefore, the charging mode does not need to be adjusted in the current period, the current charging gain is discarded, and the next detection period is waited for.

Referring to fig. 8, fig. 8 is another flow chart of a charge control method according to an embodiment of the present application, including:

s201, acquiring the current charging gain.

For calculating the equivalent charging arrangement of the current system, the specific process of calculating the charging gain can refer to the prior art, for example, the charging gain can be calculated according to parameters such as the input voltage of the primary side, the output voltage of the secondary side, the transformer transformation ratio and the like. In one example, first, an input voltage of a primary side and an output voltage of a secondary side of a current period are obtained; when at least one of the input voltage and the output voltage of the present period is changed compared with the previous period, S201 is performed, otherwise the present period is skipped. If the input voltage and the output voltage are both changed, the charging gain is not changed, so the charging mode is adjusted wirelessly in the period.

S202, acquiring a current charging mode.

In the case where the current charging mode is the PWM mode, step S203 is executed; in the case where the current charging mode is the PFM mode, step S207 is performed.

S203, judging whether the current charging gain is larger than a preset first gain threshold value.

If the current charging gain is greater than the preset first gain threshold, executing step S204; if the current charging gain is not greater than the preset first gain threshold, step S205 is performed.

S204, maintaining the charging mode as a PWM mode.

S205, judging whether the current charging gain is larger than a preset second gain threshold value and whether the current output power is larger than a preset power threshold value.

If the current charging gain is greater than the preset second gain threshold and the current output power is greater than the preset power threshold, step S206 is performed, otherwise step S204 is performed.

S206, switching the charging mode to the PFM mode.

The hardware circuit exits the PWM mode and enters the PFM mode for charging.

S207, judging whether the current charging gain is larger than a preset first gain threshold value.

If the current charging gain is greater than the preset first gain threshold, step S208 is executed; if the current charging gain is not greater than the preset first gain threshold, step S209 is performed.

S208, switching the charging mode to the PWM mode.

And exiting the PFM mode, and entering a PWM mode for charging.

S209, judging whether the current charging gain is larger than a preset second gain threshold value and whether the current output power is larger than a preset power threshold value.

If the current charging gain is greater than the preset second gain threshold and the current output power is greater than the preset power threshold, step S210 is executed, otherwise step S208 is executed.

S210, maintaining the charging mode as the PFM mode.

In the embodiment of the application, when the charging gain or the output power is smaller, the charging mode is switched from the PFM mode to the PWM mode, and the charging loss of the PWM mode is lower than that of the PFM mode under the condition of low load, so that the loss of the charging system when the load is lighter can be reduced. In addition, when the gain of the charging system is greater than the maximum gain of the LLC circuit, the LLC circuit in PFM mode may enter the capacitive region and may not operate normally.

In order to ensure the stability of the output voltage before and after the conversion of the charging mode, whether the switching is to the PFM mode or the PWM mode, a proper switching time is required to be selected. In one possible embodiment, the transistor off time may be selected as the point of time of switching to PFM mode or to PWM mode, where the transistor off time refers to the off time of the transistor (corresponding to M2 in fig. 3) corresponding to the primary side transformer.

The embodiment of the application also provides a charger, which comprises any one of the resonant circuits and the charging control chip; the charging control chip is used for controlling the resonant circuit to switch the charging mode through any one of the charging control methods in the application when the charging control chip is in operation.

In the charger provided by the embodiment of the application, the charging control chip executes the charging control method in the embodiment of the application, and the switching between the PWM mode and the PFM mode is realized through the resonant circuit in the embodiment of the application.

The resonant circuit, the charging control method and the charger can be suitable for continuous voltage regulation scenes with output voltage of 0-1000V, the power range condition range can be 100-1000W, and the charger can be suitable for requirements of fast charging protocols such as PD, UFCS, QC, SCP (Super Charge Protocol, super charging protocol).

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In this specification, each embodiment is described in a related manner, and each embodiment is mainly described in a different manner from other embodiments, so that identical and similar parts between the embodiments are referred to each other.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the scope of the present application. Any modifications, equivalent substitutions, improvements, etc. that are within the spirit and principles of the present application are intended to be included within the scope of the present application.

Claims

1. A resonant circuit, comprising:

DC-DC primary side module and DC-DC secondary side module;

2. The circuit of claim 1, wherein the DC-DC primary side module comprises a first primary side oscillator sub-module, a second primary side oscillator sub-module, and a first switch sub-module; the first primary side oscillation submodule is respectively connected with the second primary side oscillation submodule and the first switching submodule; the second primary side vibration oscillator sub-module is connected with the first switch sub-module;

3. The circuit of claim 2, wherein the first primary side oscillating submodule comprises a first capacitor, a first transistor, a second capacitor, a third capacitor, a first inductor, a third inductor, and a fifth capacitor;

4. The circuit of claim 3, wherein the second primary side oscillator sub-module comprises a fourth capacitor, a second inductor, and the first switching sub-module comprises a first switch and a second switch;

5. The circuit of claim 1, wherein the second side oscillation submodule comprises a fifth inductor, a fourth transistor and a sixth capacitor,

the first end of the fifth inductor is connected with the first end of the sixth capacitor, the second end of the fifth inductor is connected with the first end of the fourth transistor, and the second end of the fourth transistor is connected with the second end of the sixth capacitor;

the first secondary side oscillation submodule comprises a fourth inductor and a third transistor, and the second change-over switch submodule comprises a fifth transistor;

6. The circuit of claim 5, wherein the third transistor is replaced with a first diode, the fourth transistor is replaced with a second diode, and/or the fifth transistor is replaced with a third switch.

7. The circuit of claim 2, wherein the circuit further comprises: an isolation module;

8. A charging control method for controlling the switching of a charging mode of the resonant circuit according to any one of claims 1 to 7, the method comprising:

acquiring a current charging gain;

9. The method of claim 8, wherein the method further comprises:

10. The method according to claim 9, wherein the method further comprises:

11. The method of claim 8, wherein the method further comprises:

12. The method of claim 8, wherein prior to the step of obtaining the current charge gain, the method further comprises:

13. A charger comprising a charge control chip and the resonant circuit of any one of claims 1-7; the charging control chip is used for controlling the resonant circuit to switch the charging mode by the charging control method of any one of claims 8-12 when in operation.