CN116566207A - Switching power supply circuit and electronic equipment - Google Patents

Switching power supply circuit and electronic equipment Download PDF

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Publication number
CN116566207A
CN116566207A CN202210102554.7A CN202210102554A CN116566207A CN 116566207 A CN116566207 A CN 116566207A CN 202210102554 A CN202210102554 A CN 202210102554A CN 116566207 A CN116566207 A CN 116566207A
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CN
China
Prior art keywords
circuit
voltage
power supply
resistor
input end
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Pending
Application number
CN202210102554.7A
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Chinese (zh)
Inventor
周兴
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Guangzhou Shiyuan Electronics Thecnology Co Ltd
Guangzhou Shikun Electronic Technology Co Ltd
Original Assignee
Guangzhou Shiyuan Electronics Thecnology Co Ltd
Guangzhou Shikun Electronic Technology Co Ltd
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Application filed by Guangzhou Shiyuan Electronics Thecnology Co Ltd, Guangzhou Shikun Electronic Technology Co Ltd filed Critical Guangzhou Shiyuan Electronics Thecnology Co Ltd
Priority to CN202210102554.7A priority Critical patent/CN116566207A/en
Publication of CN116566207A publication Critical patent/CN116566207A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4241—Arrangements for improving power factor of AC input using a resonant converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The embodiment of the invention discloses a switching power supply circuit and electronic equipment, wherein the switching power supply circuit comprises: PFC circuit still includes: LLC circuit and signal control circuit; the PFC circuit is connected with an alternating current output end for inputting an alternating current power supply; the voltage input end of the LLC circuit is connected with the voltage output end of the PFC circuit; and the signal control circuit is connected with the voltage input end and the signal input end of the LLC circuit, and is used for controlling the inductance value of the exciting inductance in the LLC circuit to be increased when the direct current input voltage is lower than a set voltage threshold value. By utilizing the technical scheme, the related requirements of the electronic equipment on load can be met, the service performance of the electronic equipment is improved, and meanwhile, the output on load capacity of the LLC circuit during low-voltage starting is also improved.

Description

Switching power supply circuit and electronic equipment
Technical Field
The present invention relates to the field of switching power supply technologies, and in particular, to a switching power supply circuit and an electronic device.
Background
The switching power supply, also called switching power supply, switching converter and switching mode power supply, is a high-frequency electric energy conversion device and is a kind of power supply. The function is to convert a voltage of one level into a voltage or current required by the user terminal through different types of structures.
The conventional switching power supply circuit mainly comprises a power factor correction (Power Factor Correction, PFC) circuit and a resonant circuit (LLC Resonant Converter, LLC). Through the cascade connection cooperation of the PFC circuit and the LLC circuit, the switching power supply can be ensured to have proper switching frequency fluctuation.
Along with the intellectualization of electronic products, many electronic devices need to have a strong carrying capacity when turned on, especially some devices with external charging loads or with external wake-up functions. Therefore, a switching power supply for starting electronic equipment is also required to have a strong carrying capacity in the power-on process.
However, the existing switching power supply circuit using PFC circuit+llc circuit as topology circuit structure has insufficient load capacity at the time of starting, and it is necessary to control the switching power supply to start under no-load or light-load conditions. Such inherent defects cannot meet the requirements of powering on, i.e. carrying, of the electronic equipment, and affect the usability of the electronic equipment.
Disclosure of Invention
The embodiment of the invention provides a switching power supply circuit and electronic equipment, which can improve the output load capacity of an LLC circuit during low-voltage starting while improving the service performance of the electronic equipment.
In a first aspect, an embodiment of the present invention provides a switching power supply circuit, including: PFC circuit still includes: LLC circuit and signal control circuit;
the PFC circuit is connected with an alternating current output end for inputting an alternating current power supply;
the voltage input end of the LLC circuit is connected with the voltage output end of the PFC circuit;
the signal control circuit is connected with the voltage input end and the signal input end of the LLC circuit, and when the direct current input voltage of the voltage input end is lower than a set voltage threshold value, the signal control circuit controls the inductance value of the exciting inductor in the LLC circuit to be increased.
In a second aspect, an embodiment of the present invention provides an electronic device, including: the switching power supply circuit of the first aspect.
The embodiment of the invention provides a switching power supply circuit and electronic equipment, wherein the switching power supply circuit comprises: PFC circuit still includes: LLC circuit and signal control circuit; the PFC circuit is connected with an alternating current output end for inputting an alternating current power supply; the voltage input end of the LLC circuit is connected with the voltage output end of the PFC circuit; and the signal control circuit is connected with the voltage input end and the signal input end of the LLC circuit, and controls the inductance value of the exciting inductance in the LLC circuit to be increased when the direct current input voltage of the voltage input end is lower than a set voltage threshold value. By using the switching power supply circuit, the switching power supply circuit is connected with the voltage input end and the signal input end of the LLC circuit through the signal control circuit, when the direct current input voltage is lower than a set voltage threshold value, the inductance value of the exciting inductance in the LLC circuit is controlled to be increased, the purpose of meeting the load of electronic equipment is achieved, the service performance of the electronic equipment is improved, and the output load capacity of the LLC circuit during low-voltage starting is improved. The switching power supply circuit has the characteristics of low implementation cost, simple and reliable circuit and easy implementation, and has better applicability.
Drawings
FIG. 1 is a schematic diagram of an LLC circuit in the prior art;
FIG. 2 is a block diagram of a switching power supply circuit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a switching power supply circuit according to another embodiment of the present invention;
FIG. 4 is a simplified equivalent circuit diagram of an LLC circuit according to an embodiment of the present invention;
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart depicts operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently, or at the same time. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figures. The processes may correspond to methods, functions, procedures, subroutines, and the like. Furthermore, embodiments of the invention and features of the embodiments may be combined with each other without conflict.
The term "comprising" and variants thereof as used herein is intended to be open ended, i.e., including, but not limited to. The term "based on" is based at least in part on. The term "one embodiment" means "at least one embodiment".
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
Fig. 1 is a schematic diagram of an LLC circuit in the prior art, as shown in fig. 1, the LLC circuit is widely used in a switching power supply, because of the circuit characteristics of the LLC circuit, the gain (Vo output/Vin input) characteristics of the LLC circuit affect the switching frequency, and the excessively wide switching frequency fluctuation affects various performances of the power supply, in order to avoid the relatively wide frequency fluctuation, a front stage of the circuit generally receives a PFC circuit to make Vin voltage be a stable value, in the prior art, the PFC circuit+llc circuit is used as a switching power supply circuit with a topology circuit structure, because the PFC circuit+llc circuit is a cascade circuit, the PFC circuit of the front stage and the LLC circuit of the subsequent stage often need to have artificial set time sequence requirements, and the PFC circuit needs to be required to operate first, after the PFC circuit stably outputs 390V, the LLC circuit is driven to operate by a control signal, so that the output end of the LLC circuit can provide stable output power. Especially for the product with the input voltage range of 100-240Vac, when the input voltage is 100Vac, the Vin voltage is only 141V at maximum under the condition that the PFC circuit is not started, and if the timing requirement of starting the PFC circuit firstly and then the LLC circuit is not met, the circuit can trigger protection and cannot normally output, meanwhile, the load capacity is insufficient during starting, the switching power supply needs to be controlled to start under the condition of no load or light load, and the inherent defect cannot meet the requirement of powering on, namely loading, of the electronic equipment.
In view of the above, the invention provides a switching power supply circuit, which overcomes the defects in the prior art, improves the output load capacity of the LLC circuit during low-voltage starting, achieves the purpose of meeting the load of electronic equipment, and improves the service performance of the electronic equipment. The switching power supply circuit has the characteristics of low implementation cost, simple and reliable circuit and easy implementation, and has better applicability.
In an embodiment, fig. 2 is a block diagram of a switching power supply circuit according to an embodiment of the present invention, where the switching power supply circuit is suitable for a case of improving output load capacity when an LLC circuit is started at low voltage, and the switching power supply circuit may be integrated in an electronic device. As shown in fig. 2, the switching power supply circuit includes: PFC circuit 20 further includes: LLC circuit 30 and signal control circuit 40.
The PFC circuit 20 is connected to an ac output terminal for inputting an ac power supply;
the voltage input end of the LLC circuit 30 is connected with the voltage output end of the PFC circuit 20;
the signal control circuit 40 is connected to the voltage input terminal and the signal input terminal of the LLC circuit 30, and controls the inductance value of the excitation inductance in the LLC circuit 30 to increase when the dc input voltage at the voltage input terminal is lower than the set voltage threshold.
The set voltage threshold may be understood as a stable dc voltage value of the dc voltage outputted by the PFC circuit 20 that is set in advance. For example, the preset voltage value may be 390V. The low level signal may be understood as a level signal generated when the dc input voltage is below a set voltage threshold.
In this embodiment, the excitation inductance is understood to be the primary side inductance of the transformer in the LLC circuit, the current acting on the primary side inductance is not conducted to the secondary side, and the inductance is measured from the primary side by all secondary open circuits, and the secondary open circuits are used for exciting the iron core, so that ferromagnetic molecules in the iron core can be used for magnetic conduction, after winding coils are wound, a power supply is added, and magnetic force starts to exist, and the inductance is called the excitation inductance. It should be noted that, the output of the high level signal and the low level signal may be affected by the preset voltage threshold, and the number of coils serving as the exciting inductor may be affected by different high level signals and different low level signals, so that the magnitude of the inductance value of the exciting inductor is affected. Illustratively, when the signal input in the LLC circuit 30 receives a low level signal input by the signal control circuit, the inductance value of the excitation inductance in the LLC circuit 30 may be controlled to increase; when the signal input terminal of the LLC circuit 30 receives a high level signal input from the signal control circuit, the inductance value of the exciting inductance can be reduced.
In the present embodiment, the switching power supply circuit may include a PFC circuit 20, an LLC circuit 30, and a signal control circuit 40. The PFC circuit 20 is connected to an ac output terminal for inputting an ac power source, and a voltage input terminal of the LLC circuit 30 is connected to a voltage output terminal of the PFC circuit 20. The signal control circuit 40 is connected to the voltage input terminal of the LLC circuit 30 and the signal input terminal, and controls the inductance value of the exciting inductance in the LLC circuit 30 to increase when the dc input voltage of the LLC circuit 30 is lower than a predetermined voltage threshold. Illustratively, when the dc input voltage at the voltage input is below the set voltage threshold, a low level signal may be input to the LLC circuit 30 via the signal input to control an increase in the inductance value of the excitation inductance in the LLC circuit 30.
In one embodiment, the signal control circuit is configured to control the inductance value of the excitation inductor in the LLC circuit 30 to decrease when the dc input voltage reaches a set voltage threshold. Illustratively, when the dc input voltage reaches the set voltage threshold, a high level signal may be input to the LLC circuit 30 via the signal input terminal to control the reduction of the inductance value of the excitation inductance in the LLC circuit 30.
In this embodiment, the signal control circuit may be configured to input a high level signal to the LLC circuit 30 via the signal input terminal when the dc input voltage reaches a preset voltage threshold value, so as to control the reduction of the inductance value of the excitation inductance in the LLC circuit 30.
In one embodiment, the LLC circuit 30 includes: the transformer T1, the MOS tube Q2, the first inductor Ls, the capacitor Cr, the second inductor Lp, the third inductor Lp1, the MOS tube Q3 and the rectifying circuit;
the first end of the primary input end of the transformer T1 is respectively connected with the second end and the end of the capacitor Cr and the first end of the second inductor Lp; the second end of the primary input end of the transformer T1 is respectively connected with the third inductor Lp1 and the source electrode of the MOS tube Q3; the secondary input end of the transformer T1 is connected with a rectifying circuit;
the first end of the third inductor LP1 is connected with the second end of the second inductor LP, and the second end of the third inductor LP1 is connected with the drain electrode of the MOS tube Q3; the grid electrode of the MOS tube Q3 is connected with the signal input end;
the second end of the first inductor Ls is connected with the first end of the capacitor Cr, and the first end of the first inductor Ls is respectively connected with the source electrode of the MOS tube Q1 and the drain electrode of the MOS tube Q2;
the drain electrode of the MOS tube Q1 is connected with a direct-current voltage input/output end; the source electrode of the MOS transistor Q2 is grounded.
In this embodiment, the LLC circuit 30 may include a transformer T1, a MOS transistor Q2, a first inductor Ls, a capacitor Cr, a second inductor Lp, a third inductor Lp1, a MOS transistor Q3, and a rectifying circuit.
Specifically, the rectifying circuit converts an input ac voltage into a dc voltage through a rectifying diode, and may use other components. The rectifying circuit may include a full-wave rectifying diode, an output capacitor, a resistor, and the like.
In this embodiment, the first end of the primary input terminal of the transformer T1 may be understood as the primary side of the transformer T1, and the second end of the primary input terminal of the transformer T1 may be understood as the secondary side of the transformer T1. The primary side and the secondary side of the transformer T1 are all surrounded by a certain number of turns, and the number of turns is not limited.
In this embodiment, a first end of the primary input end of the transformer T1 is connected to a second end of the capacitor Cr and a first end of the second inductor Lp, and a second end of the primary input end of the transformer T1 is connected to the third inductor Lp1 and a source of the MOS transistor Q3. The secondary input end of the transformer T1 is connected with the rectifying circuit, the first end of the third inductor LP1 is connected with the second end of the second inductor LP, the second end of the third inductor LP1 is connected with the drain electrode of the MOS tube Q3, and the grid electrode of the MOS tube Q3 is connected with the signal input end. The second end of the first inductor Ls is connected with the first end of the capacitor Cr, the first end of the first inductor Ls is respectively connected with the source electrode of the MOS tube Q1 and the drain electrode of the MOS tube Q2, the drain electrode of the MOS tube Q1 is connected with the direct-current voltage input and output end, and the source electrode of the MOS tube Q2 is grounded.
Fig. 3 is a schematic structural diagram of another switching power supply circuit according to an embodiment of the present invention, where the switching power supply circuit includes: the LLC circuit 30 and the signal control circuit 40, the LLC circuit 30 further includes a rectifier circuit 301.Vin represents an input voltage, and the ps_on signal is a signal generated by the signal control circuit. As shown in fig. 3, the LLC circuit 30 includes: the transformer T1, the MOS tube Q2, the first inductor Ls, the capacitor Cr, the second inductor Lp, the third inductor Lp1, the MOS tube Q3, a PS_ON signal connected with the MOS tube Q3 and a rectifying circuit consisting of a full-wave rectifying diode D1, a full-wave rectifying diode D2, an output capacitor Cout and a resistor R. The signal control circuit 40 includes: VCC, vin, R1, R2, R3, R4, R5, QB1 and QB2, wherein VCC represents a second voltage input, i.e. a power supply for the LLC circuit to operate, this voltage is present after power up of the ac power supply, vin represents a first voltage input, i.e. the LLC input voltage, R1 represents a first resistor, R2 represents a second resistor, R3 represents a third resistor, R4 represents a fourth resistor, and R5 represents a fifth resistor.
In this embodiment, the third inductor Lp1, the MOS transistor Q3 and the ps_on signal may be used to increase the inductance of the second inductor Lp at the moment of starting the LLC, thereby increasing the gain and realizing an improvement in the load carrying capability of the LLC. The signal control circuit may be a signal provided by the I/O interface provided by the control system, that is, an output signal, or may be a signal generated by hardware control of a low Vin voltage, that is, a signal that disappears when the Vin voltage is high.
Fig. 4 is a simplified equivalent circuit structure of an LLC circuit according to an embodiment of the invention, as shown in fig. 4, since the voltage of Vin is much lower than 390V at the moment of start-up, and the gain is much higher than that of steady-state operation, the gain of the LLC circuit during start-up must be greatly increased in order to improve the start-up capability. As can be seen from the gain equation, the gain value is positively correlated with the second inductance Lp and the capacitance Cr, and inversely correlated with the first inductance Lr, so increasing the value of the second inductance Lp at the time of starting can increase the gain.
In one embodiment, when the signal input end of the LLC circuit 30 receives the low-level signal input by the signal control circuit 40, the MOS transistor Q3 is turned off; the second inductance Lp and the third inductance Lp1 serve as excitation inductances, and the excitation inductance value of the inductance increases.
In this embodiment, when the signal input end of the LLC circuit 30 receives the low-level signal input by the signal control circuit 40, the MOS transistor Q3 is turned off, and the inductance of the exciting inductor may be the second inductance Lp plus the third inductance Lp1, and the exciting inductance of the inductor increases; when the signal input end of the LLC circuit 30 receives the high-level signal input by the signal control circuit 40, the MOS transistor Q3 is turned on, and the inductance is unchanged, and the excitation inductance is the second inductance Lp, and the excitation inductance value of the inductance is reduced.
In one embodiment, when the signal input end of the LLC circuit 30 receives the high level signal input by the signal control circuit 40, the MOS transistor Q3 is turned on; the second inductance Lp serves as an excitation inductance, and the inductance value of the excitation inductance is reduced.
In this embodiment, when the signal input end of the LLC circuit 30 receives the high-level signal input by the signal control circuit 40, the MOS transistor Q3 is turned on, and the inductance is unchanged, the excitation inductance is the second inductance Lp, and the inductance value of the excitation inductance is reduced.
In one embodiment, the signal control circuit 40 includes: the first voltage input end, the second voltage input end, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the first triode QB1 and the second triode QB2;
the first voltage input end is connected with the voltage input end of the LLC circuit and is used for inputting direct current input voltage;
the second voltage input end is connected with a power supply and is used for inputting direct-current power supply voltage;
the first voltage input end is connected with a first resistor R1 and a second resistor R2, and the second end of the second resistor R2 is grounded;
the base electrode of the first triode QB1 is connected with the second end of the first resistor R1 and the first end of the second resistor R2; the collector electrode of the first triode QB1 is connected with the second voltage input end; the emitter of the first triode QB1 is connected with a third resistor R3 and a fourth resistor R4; the second end of the fourth resistor R4 is grounded;
the base electrode of the second triode QB2 is connected with the second end of the third resistor R3 and the first end of the fourth resistor R4; the collector of the second triode QB2 is connected with a second voltage input end through a fifth resistor R5; an emitter of the second triode QB2 is connected with a signal input end of the LLC circuit.
The first voltage input terminal may be an input of a voltage of the LLC circuit 30, and the second voltage input terminal may be an input of a power supply for operating the LLC circuit 30. The first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are used for dividing voltage, the first triode QB1 and the second triode QB2 can be driven to be conducted by a certain driving voltage, and when the QB1 and the second triode QB2 are in an off state, a low-level signal is input to the signal input end; when the first transistor QB1 and the second transistor QB2 are both in a turned-on state, a high level signal is input to the signal input terminal.
In the present embodiment, the signal control circuit 40 may be understood as a signal control circuit in which the ps_on signal is implemented in hardware. The signal control circuit 40 may make the first transistor QB1 be in a conducting state when the first voltage input terminal is higher, for example, about 390V, so that the second transistor QB2 conducts the ps_on signal to output a high level; when the first voltage input end is lower, the first triode QB1 is not in a conducting state, so that the second triode QB2 cannot be conducted, the PS_ON outputs a low level, the MOS tube Q3 is driven to be opened and closed, the third inductor Lp1 is connected into a resonant circuit in series when the low-voltage input is started, the function of not participating in resonance in a steady state is achieved, and therefore the higher starting capability of resonance when the voltage is input to the first voltage input end can be guaranteed.
In this embodiment, the signal control circuit 40 may include a first voltage input terminal, a second voltage input terminal, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first triode QB1, and a second triode QB2. The first voltage input end is connected with the voltage input end of the LLC circuit and is used for inputting direct current input voltage. The second voltage input end is connected with a power supply and is used for inputting direct-current power supply voltage. The first voltage input end is connected with the first resistor R1 and the second resistor R2, and the second end of the second resistor R2 is grounded. The base electrode of the first triode QB1 is connected with the second end of the first resistor R1 and the first end of the second resistor R2; the collector electrode of the first triode QB1 is connected with the second voltage input end; the emitter of the first triode QB1 is connected with a third resistor R3 and a fourth resistor R4; the second terminal of the fourth resistor R4 is grounded. The base electrode of the second triode QB2 is respectively connected with the second end of the third resistor R3 and the first end of the fourth resistor R4; the collector of the second triode QB2 is connected with a second voltage input end through a fifth resistor R5; an emitter of the second triode QB2 is connected with a signal input end of the LLC circuit.
By way of example, a specific signal control circuit is given in fig. 3. As shown in fig. 3, after the PFC circuit operates, vin is a higher voltage, for example, about 390 Vdc; when the PFC circuit does not work, vin voltage is lower, the second triode QB1 is conducted when Vin is higher, so that the QB2 is conducted to PS_ON to output high level, when Vin is lower, the first triode QB1 is not conducted, so that the second triode QB2 is not conducted, PS_ON is output low level, thereby driving the MOS transistor Q3 to be opened and closed, and the function that Lp1 is connected into a resonant circuit in series when low-voltage input is started and does not participate in resonance under steady state is realized. Thus, the resonant cavity can be ensured to realize high starting capability under the condition of very wide input Vin voltage.
In this embodiment, since the starting time is shorter, the output voltage (that is, vin voltage) of the PFC circuit is usually stabilized within a few seconds, so the third inductor Lp1 and the second inductor Lp may be wound on the same transformer, and a few turns may be added, which does not need to increase the size of the magnetic core and the skeleton, and may meet the requirements of temperature rise and electrical stress, and reduce the cost to a certain extent.
In an embodiment, when the dc input voltage of the first voltage input terminal in the signal control circuit 40 is lower than the set voltage threshold, the first transistor QB1 and the second transistor QB2 are turned off, and a low level signal is input to the signal input terminal;
when the dc input voltage at the first voltage input end in the signal control circuit 40 reaches the set voltage threshold, the first triode QB1 and the second triode QB2 are both turned on, and a high level signal is input to the signal input end.
In this embodiment, when the dc input voltage of the first voltage input terminal in the signal control circuit 40 is lower than the set voltage threshold, the first transistor QB1 and the second transistor QB2 are both in the off state, and a low level signal is input to the signal input terminal at this time, and when the dc input voltage of the first voltage input terminal in the signal control circuit 40 reaches the set voltage threshold, the first transistor QB1 and the second transistor QB2 are both in the on state, and a high level signal is input to the signal input terminal at this time.
It should be noted that, the first triode QB1 and the second triode QB2 need certain driving voltage to drive and turn on, after the first voltage input end passes through certain partial pressure, the first triode QB1 needs to be driven by certain voltage, and the driving voltage of the second triode QB2 comes from the second voltage input end through the partial pressure of R2 and R3, if the first triode QB1 can not turn on, the driving voltage of the second triode QB2 is 0, and therefore, the first triode QB1 can not be turned on due to the fact that the driving voltage value can not be reached.
In one embodiment, the set voltage threshold is a stable dc voltage value of the dc voltage output by the PFC circuit 20.
In the present embodiment, the set voltage threshold is a stable dc voltage of the dc voltage output by the PFC circuit 20.
In one embodiment, the LLC circuit 30 increases the output power as the inductance value of the excitation inductance increases.
In the present embodiment, when the inductance value of the excitation inductance increases, the LLC circuit 30 also increases the output power. The phase of increasing the inductance value of the exciting inductance is only before the steady dc voltage of the PFC circuit 20 is input, that is, the output power is increased relative to the existing inductance value, and after the steady dc voltage of the dc voltage is output, the output power remains the original switching circuit and is not increased.
The switching power supply circuit provided by the embodiment of the invention is connected with the voltage input end and the signal input end of the LLC circuit through the signal control circuit, and controls the inductance value of the exciting inductor in the LLC circuit to be increased when the direct current input voltage is lower than the set voltage threshold value, so that the purpose of meeting the load of electronic equipment is achieved, the service performance of the electronic equipment is improved, and the output load capacity of the LLC circuit during low-voltage starting is improved. The switching power supply circuit has the characteristics of low implementation cost, simple and reliable circuit and easy implementation, and has better applicability.
In an embodiment, the invention further provides an electronic device, which comprises the arbitrary switching power supply, and through the use of the switching power supply, the related requirements of the electronic device on load can be met, the use performance of the electronic device is improved, and meanwhile, the output on load capability of the LLC circuit during low-voltage starting is also improved.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.

Claims (10)

1. A switching power supply circuit, comprising: PFC circuit, its characterized in that includes: LLC circuit and signal control circuit;
the PFC circuit is connected with an alternating current output end for inputting an alternating current power supply;
the voltage input end of the LLC circuit is connected with the voltage output end of the PFC circuit;
the signal control circuit is connected with the voltage input end and the signal input end of the LLC circuit, and when the direct current input voltage of the voltage input end is lower than a set voltage threshold value, the signal control circuit controls the inductance value of the exciting inductor in the LLC circuit to be increased.
2. The switching power supply circuit according to claim 1, wherein the signal control circuit is configured to control the inductance value of the excitation inductance in the LLC circuit to decrease when the dc input voltage reaches a set voltage threshold.
3. The switching power supply circuit according to claim 1, wherein the LLC circuit includes: the transformer T1, the MOS tube Q2, the first inductor Ls, the capacitor Cr, the second inductor Lp, the third inductor Lp1, the MOS tube Q3 and the rectifying circuit;
a first end of the primary input end of the transformer T1 is respectively connected with a second end of the capacitor Cr and a first end of the second inductor Lp; the second end of the primary input end of the transformer T1 is respectively connected with the third inductor Lp1 and the source electrode of the MOS tube Q3; the secondary input end of the transformer T1 is connected with the rectifying circuit;
the first end of the third inductor LP1 is connected with the second end of the second inductor LP, and the second end of the third inductor LP1 is connected with the drain electrode of the MOS transistor Q3; the grid electrode of the MOS tube Q3 is connected with the signal input end;
the second end of the first inductor Ls is connected with the first end of the capacitor Cr, and the first end of the first inductor Ls is respectively connected with the source electrode of the MOS tube Q1 and the drain electrode of the MOS tube Q2;
the drain electrode of the MOS tube Q1 is connected with a direct-current voltage input/output end; the source electrode of the MOS tube Q2 is grounded.
4. The switching power supply circuit according to claim 1, wherein when the signal input terminal of the LLC circuit receives a low-level signal input by the signal control circuit, the MOS transistor Q3 is turned off; the second inductance Lp and the third inductance Lp1 are used as excitation inductances, and the excitation inductance value of the inductance is increased.
5. The switching power supply circuit according to claim 1, wherein the MOS transistor Q3 is turned on when the signal input terminal of the LLC circuit receives a high level signal input from the signal control circuit; the second inductance Lp is used as an excitation inductance, and the inductance value of the excitation inductance is reduced.
6. The switching power supply circuit according to claim 1, wherein the signal control circuit includes: the first voltage input end, the second voltage input end, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the first triode QB1 and the second triode QB2;
the first voltage input end is connected with the voltage input end of the LLC circuit and is used for inputting the direct current input voltage;
the second voltage input end is connected with a power supply and is used for inputting direct-current power supply voltage;
the first voltage input end is connected with a first resistor R1 and a second resistor R2, and the second end of the second resistor R2 is grounded;
the base electrode of the first triode QB1 is connected with the second end of the first resistor R1 and the first end of the second resistor R2; the collector electrode of the first triode QB1 is connected with the second voltage input end; the emitter of the first triode QB1 is connected with the third resistor R3 and the fourth resistor R4; the second end of the fourth resistor R4 is grounded;
the base electrode of the second triode QB2 is connected with the second end of the third resistor R3 and the first end of the fourth resistor R4; the collector electrode of the second triode QB2 is connected with the second voltage input end through the fifth resistor R5; and an emitter of the second triode QB2 is connected with a signal input end of the LLC circuit.
7. The switching power supply circuit according to claim 1, wherein when a dc input voltage of a first voltage input terminal in the signal control circuit is lower than the set voltage threshold, both the first transistor QB1 and the second transistor QB2 are turned off, and a low level signal is input to the signal input terminal;
when the direct current input voltage of the first voltage input end in the signal control circuit reaches the set voltage threshold, the first triode QB1 and the second triode QB2 are both conducted, and a high-level signal is input to the signal input end.
8. The switching power supply circuit according to any one of claims 1 to 7, wherein the set voltage threshold is a stable dc voltage value of a dc voltage outputted from the PFC circuit.
9. A switching power supply circuit according to any one of claims 1 to 7, wherein the LLC circuit increases in output power as the inductance value of the magnetizing inductance increases.
10. An electronic device comprising the switching power supply circuit of any one of claims 1-9.
CN202210102554.7A 2022-01-27 2022-01-27 Switching power supply circuit and electronic equipment Pending CN116566207A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210102554.7A CN116566207A (en) 2022-01-27 2022-01-27 Switching power supply circuit and electronic equipment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210102554.7A CN116566207A (en) 2022-01-27 2022-01-27 Switching power supply circuit and electronic equipment

Publications (1)

Publication Number Publication Date
CN116566207A true CN116566207A (en) 2023-08-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210102554.7A Pending CN116566207A (en) 2022-01-27 2022-01-27 Switching power supply circuit and electronic equipment

Country Status (1)

Country Link
CN (1) CN116566207A (en)

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