WO2017220019A1 - 开关电源、电子设备及开关电源控制方法 - Google Patents

开关电源、电子设备及开关电源控制方法 Download PDF

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Publication number
WO2017220019A1
WO2017220019A1 PCT/CN2017/089760 CN2017089760W WO2017220019A1 WO 2017220019 A1 WO2017220019 A1 WO 2017220019A1 CN 2017089760 W CN2017089760 W CN 2017089760W WO 2017220019 A1 WO2017220019 A1 WO 2017220019A1
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Prior art keywords
power supply
switching
circuit
switching circuit
output
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PCT/CN2017/089760
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English (en)
French (fr)
Inventor
王林国
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中兴通讯股份有限公司
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Publication of WO2017220019A1 publication Critical patent/WO2017220019A1/zh

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    • 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

Definitions

  • the present disclosure relates to the field of electronic technologies, for example, to a switching power supply, an electronic device, and a switching power supply control method.
  • the switching power supply is usually controlled by Pulse Width Modulation (PWM), such as the buck conversion circuit (buck circuit) shown in FIG.
  • PWM Pulse Width Modulation
  • the switching power supply has a large duty ratio when the input voltage range is wide, and the conversion efficiency (the ratio of the output power of the switching power supply to the input power) is low, and it is not easy to implement a soft switching technique to reduce the switching loss.
  • an improved secondary switching power supply is proposed.
  • the latter stage of the improved secondary switching power supply adopts a fixed duty cycle circuit structure, the output voltage of the front stage circuit is higher, and the conversion efficiency is correspondingly higher.
  • 2 is a schematic structural view of a modified secondary switching power supply.
  • the structure of the secondary switching power supply is a two-stage series structure, the front and rear stage circuits all need to process all the power, which affects the overall conversion efficiency of the switching power supply.
  • the present disclosure provides a switching power supply, an electronic device, and a switching power supply control method, which solves the technical problem that the switching power supply has low conversion efficiency in the related art.
  • the present disclosure provides a switching power supply, including:
  • the output power of the switching power supply undertaken by the first switching circuit is smaller than the output power of the second switching circuit, and the conversion efficiency of the first switching circuit is smaller than the conversion efficiency of the second switching circuit.
  • the present disclosure also provides an electronic device including the switching power supply as described above.
  • the disclosure also provides a switching power supply control method, including:
  • the voltage control unit is electrically connected to the first switch circuit, the first switch circuit is cascaded with the second switch circuit; the first switch circuit and the second switch circuit are shared by power sharing Assuming that the output power of the switching power supply is smaller than the output power of the second switching circuit, the conversion efficiency of the first switching circuit is smaller than the second switching circuit Conversion efficiency.
  • a switching power supply, an electronic device, and a switching power supply control method include a cascaded first switching circuit and a second switching circuit, and share the output power of the switching power supply in a power sharing manner, and simultaneously pass the voltage control unit. Adjusting the input voltage or the output voltage of the first switching circuit so that the input voltage of the second switching circuit operates within a preset range, and then outputting the output voltage of the second switching circuit as an output voltage of the switching power supply, thereby improving the switching power supply Conversion efficiency.
  • FIG. 1 is a schematic structural view of a switching power supply in a related art
  • FIG. 2 is a schematic structural view of an improved secondary switching power supply in the related art
  • FIG. 3 is a schematic structural diagram of a switching power supply provided in Embodiment 1;
  • Embodiment 4 is a schematic structural diagram of another switching power supply provided in Embodiment 1;
  • FIG. 5 is a schematic structural diagram of a second switch circuit according to Embodiment 2;
  • FIG. 5 is a schematic structural diagram of a second switch circuit according to Embodiment 2;
  • FIG. 6 is a schematic structural diagram of an isolated switching power supply provided in Embodiment 2;
  • FIG. 7 is a schematic structural diagram of a non-isolated switching power supply provided in Embodiment 2;
  • Embodiment 8 is a schematic structural diagram of another non-isolated switching power supply provided in Embodiment 2;
  • FIG. 9 is a schematic structural diagram of an isolated switching power supply provided in Embodiment 3.
  • the embodiment provides a switching power supply, an electronic device, and a switching power supply control method, where the switching power supply includes a cascaded first switch circuit and a second switch circuit, and The output power of the switching power supply is shared by the power sharing; the voltage control unit further adjusts the input voltage or the output voltage of the first switching circuit to control the input voltage of the second switching circuit in a preset range
  • the output voltage of the second switching circuit is output as the output voltage of the switching power supply, thereby improving the conversion efficiency of the switching power supply.
  • the preset range includes an input voltage range of the second switching circuit that makes the conversion efficiency of the second switching circuit higher than a required value.
  • the preset range adopts an input voltage range of the second switching circuit with the highest conversion efficiency
  • the voltage control unit can control the input voltage of the first switching circuit
  • the cascade means that the two switching circuits are connected in a certain manner, such as series, parallel or series and parallel combination.
  • FIG. 3 is a schematic structural diagram of a switching power supply according to an embodiment.
  • the switching power supply includes a first switching circuit 31, a second switching circuit 32, an input voltage control unit 33, an input power source 34, and three electrolytic capacitors 35, 36, and 37; the positive and negative terminals of the input end of the first switching circuit 31
  • An electrolytic capacitor 35 is electrically connected between the two ends for electrically filtering, and the other electrolytic capacitor 36 is electrically connected between the positive and negative terminals of the input end of the second switching circuit 32 for filtering, and the output ends of the first switching circuit 31 and the second switching circuit 32 are respectively
  • the third electrolytic capacitor 37 is electrically connected for filtering; the input end of the first switching circuit 31 is connected in series with the input end of the second switching circuit 32, and is electrically connected to the input end of the input power source 34, and the output end of the first switching circuit 31
  • the input terminal of the input voltage control unit 33 is electrically connected to the output terminal
  • the terminal is electrically connected to the switch tube (not shown in FIG. 3) of the first switch circuit 31 for adjusting the input voltage of the first switch circuit 31, thereby controlling the input voltage of the second switch circuit 32 to be located.
  • Input voltage range having a high conversion efficiency of the second switching circuit 32, a second switching circuit 32 such that the output voltage of the final desired value.
  • the first switching circuit 31 and the second switching circuit 32 may employ a power supply topology such as a buck, a boost converter circuit, a buck-boost converter circuit, a forward, a flyback, a push-pull or a bridge.
  • the second switch circuit 32 may further include an unregulated or semi-regulated control circuit, wherein the circuit of the semi-regulated structure can realize the voltage regulation of the output voltage within a limited range, and the conversion of the switching power supply in the range More efficient.
  • the circuit of the unregulated structure has a fixed duty ratio and a high conversion efficiency.
  • the first switch circuit 31 and the second switch circuit 32 are isolated circuits, so the switching power supply is isolated. power supply.
  • the input voltage control unit 33 adjusts the input voltage of the first switching circuit 31 to control the input voltage of the second switching circuit 32 to be within an input voltage range that enables the switching power supply to have a higher conversion efficiency, for the isolated switching power supply There is no need to feed back the output voltage from the secondary side of the switching power supply through an isolation device such as an optocoupler, which brings benefits to the volume control and life of the switching power supply.
  • the first switch circuit 31 can be composed of a plurality of power supply systems connected in parallel, in series or in series, and correspondingly, the second switch circuit 32 can also be composed of a plurality of power supply topologies connected in series, in parallel or in series.
  • each power supply topology is connected in parallel; when the second switching circuit 32 includes at least two power supply topologies, the respective power supply topologies are connected in parallel.
  • the switching power supply shown in FIG. 3 adopts a structure in which the first switching circuit 31 is connected in series with the input end of the second switching circuit 32, and the output terminal is connected in parallel, so that the first switching circuit 31 with low conversion efficiency only bears a small part of the output power. , thereby improving the overall conversion efficiency of the switching power supply. Meanwhile, since the first switching circuit 31 employs input voltage feedforward control, the input voltage of the second switching circuit 32 is controlled by the input voltage control unit 33, so that the input voltage of the second switching circuit 32 operates at an input voltage range of higher conversion efficiency. Inside.
  • FIG. 4 is a schematic structural diagram of another switching power supply according to the embodiment.
  • the switching power supply includes a first switching circuit 41, a second switching circuit 42, an input power source 45, and three electrolytic capacitors 46, 47, and 48.
  • An electrolytic capacitor 46 is connected between the positive and negative terminals of the output end of the first switching circuit 41.
  • another electrolytic capacitor 47 is connected between the positive and negative terminals of the input end of the second switching circuit 42 for filtering, and the input end of the first switching circuit 41 and the output end of the second switching circuit 42 are both connected to the third electrolytic capacitor.
  • the first switch circuit 41 directly controls the final output voltage of the second switch circuit 42 to a desired value by means of feedforward of the input voltage (ie, the output voltage of the second switch circuit 42), and at the same time, for isolation.
  • the type of switching power supply this control mode can also avoid the feedback output voltage from the auxiliary side of the switching power supply through the isolation device such as optocoupler, which brings benefits to the volume control and life of the switching power supply.
  • the first switch circuit 41 can adopt a voltage-stabilized switch circuit to control the input voltage of the second switch circuit 42 in a feedback manner within the input voltage range of the second switch circuit 42 having a high conversion efficiency. So that the output voltage of the second switching circuit 42 is a desired value, that is, the first switch The output of the circuit 41 is connected in series with the input of the second switching circuit 42 to ensure that the input voltage of the second switching circuit 42 is within the input voltage range of the second switching circuit 42 having a higher conversion efficiency.
  • an input voltage control unit 43 is also included in FIG. 4, by which the input voltage feedforward control is implemented.
  • the input end of the input voltage control unit 43 is electrically connected to the input end of the first switch circuit 41, and the output end of the input voltage control unit 43 is electrically connected to the switch tube (not shown) of the first switch circuit 41 for
  • the input voltage of the first switching circuit 41 is adjusted to control the input voltage of the second switching circuit 42 to operate within a high conversion efficiency input voltage range such that the final output voltage of the second switching circuit 42 is a desired value.
  • the above switch tube may be a metal oxide semiconductor (MOS), and other field effect transistors may also be used. The present embodiment will be described below by taking a MOS tube as an example.
  • FIG. 4 also includes an output voltage control unit 44 through which output voltage feedback control is implemented.
  • the input end of the output voltage control unit 44 is electrically connected to the output end of the first switch circuit 41, and the output end of the output voltage control unit 44 is electrically connected to the switch tube (not shown) of the first switch circuit 41 for
  • the output voltage of the first switching circuit 41 is adjusted to control the input voltage of the second switching circuit 42 to operate within a high conversion efficiency input voltage range such that the input voltage of the second switching circuit 42 is within a preset range.
  • the first switching circuit 41 in FIG. 4 needs to perform bidirectional operation, that is, the output voltage and the output current of the first switching circuit 41 may be reversed, and the power of the power may be at the input of the first switching circuit 41. Two-way transfer between the end and the output. In this connection mode, it is guaranteed that the power of the power is transmitted from the input power terminal (left) to the load terminal (right). Double-quadrant operation can be realized by synchronous rectification circuit, such as synchronous buck, boost and various synchronous rectification bridge circuits.
  • the second switching circuit 42 can be a circuit such as buck, boost, buckboost, forward, flyback, push-pull, or bridge, or a high-efficiency circuit with semi-regulated or unregulated control.
  • the first switch circuit 41 can be composed of a plurality of power supply systems connected in parallel, in series or in series.
  • the second switch circuit 42 can also be composed of a plurality of power supply topologies connected in series, in parallel or in series, for example, at least one of the following.
  • the first switching circuit 41 includes at least two power supply topologies
  • the respective power supply topologies are connected in parallel
  • the second switching circuit 42 includes at least two power supply topologies
  • the respective power supply topologies are connected in parallel.
  • the feedforward control mode of the input voltage control unit 43 can also avoid the use of isolation devices such as optocouplers, thereby reducing the volume of the switching power supply and increasing the service life.
  • the embodiment further provides an electronic device including the foregoing switching power supply.
  • the switching power supply provided in this embodiment is cascaded with the second switching circuit through the cascaded first switching circuit.
  • the output power of the switching power supply is assumed in a power sharing manner, so that the first switching circuit having a relatively low conversion efficiency only bears a small portion of the output power, thereby improving the conversion efficiency of the entire switching power supply.
  • Controlling the voltage of the first switching circuit by the voltage control unit such that the input voltage of the second switching circuit is within an input voltage range that causes the second switching circuit to have a higher conversion efficiency, thereby controlling the output voltage of the second switching circuit to be
  • the value is required to improve the conversion efficiency of the switching power supply.
  • the present embodiment is explained based on the switching power supply shown in FIG. 3, that is, the first switching circuit is connected in series with the input end of the second switching circuit, and the output terminals are connected in parallel. This embodiment will be described.
  • FIG. 5 is a schematic structural diagram of a second switch circuit according to an embodiment.
  • the second switch circuit is an LLC resonant circuit
  • the LLC resonant circuit includes a resonant inductor 51, a resonant capacitor 52, a magnetizing inductor 53, a transformer 54, and an output.
  • the resonant inductor 51 and the resonant capacitor 52 are connected in series, the exciting capacitor 53 is connected in parallel with the primary side of the transformer 54, the resonant capacitor 52 is connected to the same end of the transformer 54, and the switching transistor 55 is connected in series between the positive and negative terminals of the input power input, and the resonant inductor
  • the input terminal of the 51 is connected to the output end of the upper MOS transistor 551 of the switch 55; the two ends of the transformer 54 are respectively connected to a MOS transistor 57 and 58 between the drain and the source of the two MOS transistors 57 and 58.
  • a diode is connected in parallel to prevent reverse breakdown of the MOS transistors 57 and 58; the drains of the two MOS transistors 57 and 58 are connected in series and connected to the anode of the capacitor 56, and the cathode of the output capacitor 56 is connected to the secondary side of the transformer 54.
  • the same name end of the coil 541 is connected to the output of the switching power supply.
  • the switching frequency of the switching transistor when the switching frequency of the switching transistor operates at the resonant frequency point formed by the resonant inductor 51 and the resonant capacitor 52, the soft switching of the rectifier circuit of the primary side and the secondary side of the transformer 54 can be realized, and the switching loss can be reduced.
  • the voltage and current waveforms on the primary side are synchronized, and the power transmission efficiency is the highest, so that high power conversion efficiency can be achieved.
  • the switching frequency can be made very high and the power density of the power supply is effectively improved.
  • the maximum efficiency of the LLC resonant circuit is realized at the resonance point.
  • the gain of the resonant circuit is 1, and the ratio of the input voltage to the output voltage of the LLC resonant circuit is the primary side and the secondary side turns ratio N:1 of the transformer 54.
  • the switching frequency of the LLC resonant circuit needs to be varied within a large range, so that the LLC resonant circuit achieves the required gain.
  • the waveforms of voltage and current are no longer synchronized, the energy transfer efficiency is low (regardless of power factor), there is energy feedback, and the root mean square value RMS (RMS meam square, RMS) is high, resulting in increased conduction loss, power supply energy.
  • the transmission efficiency is reduced.
  • FIG. 6 is a schematic structural diagram of an isolated switching power supply according to the embodiment.
  • the isolated structure includes a first switch circuit 61, a second switch circuit 62, an input voltage control unit 63, and three The electrolytic capacitor, wherein the second switching circuit 62 adopts the LLC resonant circuit of FIG. 5, and the transformer represents the LLC resonant circuit in FIG. 6.
  • the first switching circuit 61 uses a flyback isolation circuit including a transformer 611, a MOS transistor 612 located on the primary side of the transformer 611, a MOS transistor 613 on the secondary side of the transformer 611, and the MOS transistor 613.
  • the diode 614 is electrically connected; the non-identical end of the transformer 611 is electrically connected to the drain of the MOS transistor 612.
  • the gate of the MOS transistor 612 is electrically connected to the input voltage control unit 63.
  • the source of the MOS transistor 612 and the negative electrode of the electrolytic capacitor are electrically connected.
  • the electrolytic capacitor is connected in parallel to the primary side of the transformer 611 and electrically connected to the input end of the input power source, the input end of the input voltage control unit 63 is electrically connected to the negative pole of the electrolytic capacitor; the same name end of the transformer 611 and the MOS tube 613
  • the drain is electrically connected, and a diode 614 is connected in parallel between the drain and the source of the MOS transistor 613 to prevent the MOS transistor 613 from being reversely broken.
  • the input end of the second switch circuit 62 is connected in series with the input end of the first switch circuit 61 and is connected to the input end of the input power source.
  • the output end of the second switch circuit 62 is connected in parallel with the output end of the first switch circuit 61 and is electrically connected to the other end.
  • An electrolytic capacitor electrically connected to an output of the switching power supply, and an input of the second switching circuit 62 is electrically coupled to an input of the input voltage control unit 63.
  • the flyback isolation circuit controls the input voltage of the LLC resonant circuit to be N*Vo by the input voltage feedforward control mode, where Vo is the output voltage of the required switching power supply, and N is the LLC resonant circuit.
  • Vo is the output voltage of the required switching power supply
  • N is the LLC resonant circuit.
  • the LLC resonant circuit can operate at the highest conversion efficiency point, and the portion where the input voltage Vin exceeds N*Vo is regulated by the input voltage of the flyback circuit.
  • the control method includes: when the input voltage of the input LLC resonant circuit is higher than N*Vo, the flyback isolation circuit reduces the duty ratio, thereby reducing the power output, causing the output power of the LLC resonant circuit portion to increase, and the input capacitor is discharged. The input voltage of the LLC resonant circuit drops.
  • the input terminals of the flyback isolation circuit and the LLC resonant circuit are in series, the input currents of the two are equal in steady state, so the input power of the flyback isolation circuit and the LLC resonant circuit is proportional to the respective input voltages.
  • Vin is close to N*Vo, the input voltage of the flyback isolation circuit is much smaller than that of the LLC resonant circuit, that is, the flyback isolation circuit with lower conversion efficiency is only responsible for a small part of the power.
  • Most of the output power of the switching power supply is provided by the LLC resonant circuit operating at the resonance point, so that the overall conversion efficiency of the switching power supply can be improved.
  • the LLC resonant circuit can realize the soft switching of the primary side and the secondary side of the transformer in the LLC resonant circuit, which is beneficial to increase the switching frequency, reduce the volume of the switching power supply, and thereby increase the power density; and in this embodiment, the flyback
  • the isolated circuit adopts the input voltage feedforward control mode, and the isolation device such as the optocoupler required for the output voltage feedback of the conventional flyback isolation circuit can improve the power density of the overall power supply.
  • FIG. 7 is a schematic structural diagram of a non-isolated switching power supply according to the embodiment.
  • the non-isolated circuit includes a first switch circuit 71, a second switch circuit 72, an input voltage control unit 73, and three.
  • the first switching circuit 71 employs a non-isolated buck circuit including two MOS transistors (ie, the switching transistor 711) and an inductor 712.
  • the source of one MOS transistor 7111 is electrically connected to the drain of the other MOS transistor 7112, and is electrically connected to the anode of the inductor 712.
  • An electrolytic capacitor 74 is connected in parallel between the positive and negative terminals of the input end of the second switch circuit 72 for filtering, and another electrolytic capacitor 75 is connected in parallel between the positive and negative terminals of the input end of the first switch circuit 71 for filtering, and the input end of the first switch circuit 71 is
  • the input end of the second switch circuit 72 is connected in series to the input end of the input power source, the input end of the input voltage control unit 73 is connected to the positive terminal of the electrolytic capacitor 75, and is connected to the input end of the second switch circuit 72; the input voltage control unit
  • the output end of 73 is electrically connected to the gates of the two MOS transistors 7111 and 7112, wherein the drain of the MOS transistor 7111 is electrically connected to the input terminal of the input voltage control unit 73, and the output of the first switch circuit
  • the non-isolated buck circuit Since the non-isolated buck circuit does not include the input-output isolation characteristics of the transformer, the input voltage negative terminal of the non-isolated buck circuit needs to be grounded.
  • the LLC resonant circuit has an isolation characteristic.
  • the positive terminal of the input voltage is electrically connected to the positive terminal of the input power source, and Vin is the input voltage value of the input power source.
  • the non-isolated buck circuit uses an input voltage feedforward method to control the input voltage of the non-isolated buck circuit to be Vin-N*Vo, where Vo is the output voltage of the required switching power supply.
  • the input voltage of the LLC resonant circuit is N*Vo, where N is the input and output voltage gain of the LLC resonant circuit.
  • the control method is that when the input voltage of the non-isolated buck circuit is high, the duty ratio is increased, the transfer energy of the non-isolated buck circuit is increased, the electrolytic capacitor of the non-isolated buck circuit is discharged, and the input voltage is lowered.
  • FIG. 8 is a schematic structural diagram of another non-isolated switching power supply according to the embodiment.
  • the non-isolated switching power supply includes a first switch circuit 81, a second switch circuit 82, and an input voltage. Control unit 83 and three electrolytic capacitors.
  • the first switch circuit 81 adopts the circuit structure of the first switch circuit 61 in FIG. 6, that is, a flyback isolation circuit is used.
  • the input end of the first switch circuit 81 is electrically connected to the input end of the input power supply in series with the input end of the second switch circuit 82, and the input end of the input voltage control unit 83 is electrically connected to the negative end of the input end of the first switch circuit 81, and the output end is connected. It is electrically connected to the gate of the MOS transistor (ie, the switching transistor) in the first switching circuit 81.
  • An electrolytic capacitor 84 is connected in parallel between the positive and negative terminals of the input terminal of the first switching circuit 81, and the parallel connection between the positive and negative terminals of the second switching circuit 82 is another.
  • Electrolytic capacitor 85 first switching circuit 81 is connected in parallel with the output of second switching circuit 82 and is connected to another electrolytic capacitor 86, which is connected to the output of the switching power supply.
  • the control mode of the non-isolated switching power supply in FIG. 8 is similar to that of FIG. 6, and therefore will not be described herein.
  • the input voltage control unit adjusts the input voltage of the first switching circuit such that the input voltage of the second switching circuit operates within an input voltage range of a higher conversion efficiency, thereby improving the conversion efficiency of the switching power supply.
  • the input control circuit feedforward mode can be adopted, and it is not necessary to feed back the output voltage from the secondary side of the switching power supply through the isolation device such as the optocoupler, which is beneficial to reducing the volume of the switching power supply and increasing the service life.
  • the present embodiment is explained based on the switching power supply shown in FIG. 4, that is, the output end of the first switching circuit is electrically connected to the input end of the second switching circuit.
  • the input of a switching circuit is electrically coupled to the output of the second switching circuit as described below.
  • FIG. 9 is a schematic structural diagram of an isolated switching power supply according to the embodiment.
  • the isolated switching power supply includes a first switching circuit 91, a second switching circuit 92, an input voltage control unit 93, and three electrolytic capacitors.
  • the second switch circuit 92 is composed of the aforementioned LLC resonant circuit, and is represented by a transformer in FIG. 9. For the structure of the LLC resonant circuit, details are not described herein again.
  • the first switch circuit 91 uses a conventional full-bridge synchronous rectification circuit including a transformer 911, an inductor 912, two MOS transistors 913 and 914 on the secondary side of the transformer 911, and diodes 915 and 916 on the MOS transistors 913 and 914, Transformer 911 primary side four MOS tubes 917, 918, 919 and 920 and two on the four MOS tubes
  • the pole tube ie, the left side of the transformer 911 in FIG.
  • MOS transistor 9 is the secondary side and the right side is the primary side), and four MOS tubes are connected in parallel between the two ends of the transformer 911, wherein the drains of the MOS tubes 917 and 919 are both the primary side of the transformer 911
  • the terminals of the same name are connected, and the sources of the MOS transistors 918 and 920 are both connected to the non-identical end of the primary side of the transformer 911; the source of the MOS transistor 917 is connected to the drain of the MOS transistor 918, and the source of the MOS transistor 919 and the drain of the MOS transistor 920 are leaked.
  • a diode 915 is connected in parallel between the drain and the source of the MOS transistor 913, and a diode 916 is connected in parallel between the drain and the source of the MOS transistor 914 to prevent the MOS transistors 913 and 914 from being reversely broken.
  • the MOS transistor 913 The source of the inductor 912 is electrically connected to the upper and lower coils 921 and 922 of the secondary side of the transformer 911, and the anode of the inductor 912 is electrically connected to the input power source 94.
  • the input end of the input voltage control unit 93 is connected in parallel with the input end of the first switch circuit 91, and is connected in series with the output end of the second switch circuit 92.
  • the output end of the input voltage control unit 93 is connected to the primary side of the transformer of the first switch circuit 91.
  • the four MOS transistors are electrically connected, the output end of the first switch circuit 91 is connected in series with the input end of the second switch circuit 92, and is connected to the input end of the input power source 94, the output end of the second switch circuit 92 and the input of the first switch circuit 91.
  • the terminal is electrically connected and connected to an electrolytic capacitor 95.
  • the electrolytic capacitor 95 is electrically connected to the output end of the switching power supply, and another electrolytic capacitor 96 is connected in parallel between the positive and negative terminals of the output end of the first switching circuit 91, and the second switching circuit is connected.
  • Another electrolytic capacitor 97 is connected in parallel between the positive and negative terminals of the 92 input terminal.
  • the output of the LLC resonant circuit is the primary switching input power supply connected to the primary input of the full-bridge synchronous rectifier circuit, the secondary output of the full-bridge synchronous rectifier circuit and the input of the LLC resonant circuit.
  • the terminals are connected in series to the input power source 94.
  • the secondary side of the full-bridge synchronous rectification circuit uses a synchronous rectification circuit composed of MOS tubes to ensure bidirectional flow of current.
  • the first switching circuit 91 controls Vo to a desired value by means of feedforward of the input voltage (ie, the output voltage Vo of the second switching circuit 92, Vo is the desired output voltage of the switching power supply).
  • the control mode is: when Vo is higher than the required value, the first switching circuit 91 increases the duty ratio, the increased energy is transmitted from the primary side to the secondary side, and the output voltage of the first switching circuit 91 is increased, so that the second The input voltage of the switching circuit 92 is lowered, thereby reducing the output voltage Vo of the second switching circuit such that the final output voltage of the switching power supply is a desired value.
  • the switching power supply provided in this embodiment adopts an input voltage feedforward manner to control the input voltage of the second switching circuit to operate in a high conversion efficiency input voltage range, thereby improving the overall conversion efficiency of the switching power supply, and adopting an isolated type.
  • Switching power supply, in the control mode of input voltage feedforward can also avoid the use of isolation devices such as optocouplers to increase the volume of switching power supply and reduce the service life of switching power supply.
  • This embodiment provides a switching power supply control method based on the first embodiment.
  • the control method corresponds to the switching power supply device provided in the embodiment. Therefore, the switching power supply structure will not be described in detail in this embodiment.
  • the switching power supply control method provided by the implementation includes:
  • the voltage control unit is electrically connected to the first switch circuit, the first switch circuit is cascaded with the second switch circuit; the first switch circuit and the second switch circuit are shared by power sharing Assuming that the output power of the switching power supply is smaller than the output power of the second switching circuit, the conversion efficiency of the first switching circuit is smaller than the second switching circuit Conversion efficiency.
  • the input end of the first switching circuit is connected in series with the output end of the second switching circuit, and then connected to the output end of the switching power supply, and the output end of the first switching circuit is connected in series with the input end of the second switching circuit.
  • the input end of the voltage control unit is connected to the output end of the switching power supply, and the output end of the voltage control unit is connected to the switching tube of the first switching circuit, wherein the first switching circuit comprises a synchronous rectification circuit
  • the following switching power supply control mode can be adopted:
  • the voltage control unit controls the input voltage of the second switching circuit to be within a preset range by adjusting the input voltage of the first switching circuit, and outputs the output voltage of the second switching circuit as an output voltage of the switching power supply.
  • the input end of the first switching circuit is connected in series with the output end of the second switching circuit, and then connected to the output end of the switching power supply, and the output end of the first switching circuit is connected in series with the input end of the second switching circuit.
  • the input end of the voltage control unit is connected to the input end of the switching power supply, and the output end of the voltage control unit is connected to the switching tube of the first switching circuit, wherein the first switching circuit comprises a synchronous rectification circuit
  • the following switching power supply control mode can be adopted:
  • the voltage control unit controls the output voltage of the second switching circuit to be within a preset range by adjusting the output voltage of the first switching circuit, and outputs the output voltage of the second switching circuit as an output voltage of the switching power supply.
  • the input end of the first switching circuit is connected in series with the input end of the second switching circuit, and is connected to the input end of the switching power supply, and the output end of the first switching circuit and the output end of the second switching circuit are Connected in parallel to the output end of the switching power supply, the input end of the voltage control unit is connected to the input end of the switching power supply, and the output end of the voltage control unit is connected to the switching tube of the first switching circuit;
  • the switching power supply structure can adopt the following switching power supply control mode, as follows:
  • the voltage control unit controls the input voltage of the second switching circuit to be within a preset range by adjusting the input voltage of the first switching circuit, and outputs the output voltage of the second switching circuit as an output voltage of the switching power supply.
  • the foregoing preset range includes an input voltage range with a high conversion efficiency.
  • the preset range adopts an input voltage range with the highest conversion efficiency;
  • the foregoing cascade refers to that the input and output of the two switching power supplies are connected in a certain manner, such as Series, parallel, series and parallel combination.
  • the first switching circuit and the second switching circuit may each adopt a power topology such as buck, boost, buckboost, forward, flyback, push-pull or bridge.
  • the second switching circuit can also adopt an unregulated or semi-regulated control circuit, wherein the circuit of the semi-regulated structure can realize the voltage regulation of the output voltage within a limited range, and the conversion efficiency of the power supply is high and unstable in this range.
  • the circuit of the press structure has a fixed duty ratio and a high conversion efficiency.
  • the switching power supply is an isolated switching power supply; and the input voltage control unit controls the input voltage of the second switching circuit by adjusting the input voltage of the first switching circuit.
  • the isolated switching power supply it is not necessary to feed back the output voltage from the secondary side through an isolation device such as an optocoupler, which brings benefits to the volume control and life of the power supply.
  • the input voltage of the first switching circuit is controlled by the input voltage control unit, so that the input voltage of the second switching circuit operates within a higher efficiency input voltage range, thereby Improve the conversion efficiency of the entire switching power supply.
  • the output voltage of the first switching circuit is controlled by the output voltage control unit, so that the input voltage of the second switching circuit operates in a higher efficiency input voltage range, thereby improving Conversion efficiency of the entire switching power supply.
  • the input voltage of the second switching circuit is effectively controlled by feedforward or feedback to operate in a higher efficiency input voltage range, so that the final output voltage of the switching power supply is a desired value. , thereby improving the conversion efficiency of the switching power supply.
  • the present disclosure provides a switching power supply, an electronic device, and a switching power supply control method, including a cascaded first switching circuit and a second switching circuit, and adjusting an input voltage or an output voltage of the first switching circuit by a voltage control unit, so that The input voltage of the second switching circuit operates within a preset range, and then the output voltage of the second switching circuit is output as the output voltage of the switching power supply, thereby improving the switching power supply. Conversion efficiency.

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Abstract

一种开关电源、电子设备及开关电源控制方法，开关电源包括级联的第一开关电路(31)与第二开关电路(32)，并以功率共同分担的方式承担开关电源的输出功率，同时，通过输入电压控制单元(33)对第一开关电路的输入电压或输出电压进行调整，使得第二开关电路的输入电压工作在预设范围内，并将第二开关电路的输出电压作为开关电源的输出电压输出，从而提高开关电源的转换效率。

Description

开关电源、电子设备及开关电源控制方法 技术领域
本公开涉及电子技术领域，例如涉及一种开关电源、电子设备及开关电源控制方法。
背景技术
在相关技术中，开关电源通常采用脉冲宽度调制(Pulse Width Modulation，PWM)控制，如图1所示的降压式变换电路(buck电路)。但这种开关电源在输入电压的范围较宽时占空比变化较大，转换效率(开关电源的输出功率与输入功率的比值)较低，不容易实现软开关技术以减小开关损耗。
针对上述开关电源占空比变化较大，转换效率较低的问题，一种改进型二级开关电源被提出。改进型二级开关电源的后级采用固定占空比的电路结构，前级电路的输出电压较高，转换效率也相应较高。图2为改进型二级开关电源的结构示意图。但由于该二级开关电源的结构为二级串联结构，前后级电路均需要处理全部的功率，影响开关电源的整体转换效率。
发明内容
本公开提供一种开关电源、电子设备及开关电源控制方法，解决了相关技术中开关电源转换效率较低的技术问题。
本公开提供一种开关电源，包括：
级联的第一开关电路与第二开关电路，并以功率分担的方式共同承担开关电源的输出功率；还包括电压控制单元，与所述第一开关电路电连接，所述电压控制单元设置为：通对所述第一开关电路的输入电压或输出电压进行调整，以控制所述第二开关电路的输入电压在预设范围内，将所述第二开关电路的输出电压作为开关电源的输出电压；
其中，所述第一开关电路所承担的开关电源的输出功率小于所述第二开关电路所承担的输出功率，所述第一开关电路的转换效率小于所述第二开关电路的转换效率。
本公开还提供了一种电子设备，包括如上所述的开关电源。
本公开还提供了一种开关电源控制方法，包括：
利用电压控制单元调整第一开关电路的输入电压或输出电压以控制所述第二开关电路的输入电压在预设范围内；
将第二开关电路的输出电压作为所述开关电源的输出电压输出；
其中，所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联；所述第一开关电路与第二开关电路以功率分担的方式共同承担开关电源的输出功率；所述第一开关电路所承担的开关电源的输出功率小于所述第二开关电路所承担的输出功率，所述第一开关电路的转换效率小于所述第二开关电路的转换效率。
根据本公开提供的开关电源、电子设备及开关电源控制方法，包括级联的第一开关电路与第二开关电路，并以功率共同分担的方式承担开关电源的输出功率，同时，通过电压控制单元对第一开关电路的输入电压或输出电压进行调整，使得第二开关电路的输入电压工作在预设范围内，然后将第二开关电路的输出电压作为开关电源的输出电压输出，从而提高开关电源的转换效率。
附图说明
图1为相关技术中开关电源的结构示意图；
图2为相关技术中的改进型二级开关电源的结构示意图；
图3为实施例一提供的开关电源结构示意图；
图4为实施例一提供的另一开关电源结构示意图；
图5为实施例二提供的第二开关电路结构示意图；
图6为实施例二提供的隔离型开关电源结构示意图；
图7为实施例二提供的非隔离型开关电源结构示意图；
图8为实施例二提供的另一非隔离型开关电源结构示意图；
图9为实施例三提供的隔离型开关电源结构示意图。
具体实施方式
下面通过具体实施方式结合附图对本公开作进一步详细说明。在不冲突的情况下，以下实施例和实施例中的特征可以相互组合。
实施例一
为了解决相关技术中开关电源转换效率较低的问题，本实施例提供了一种开关电源、电子设备及开关电源控制方法，该开关电源包括级联的第一开关电路与第二开关电路，并以功率共同分担的方式承担开关电源的输出功率；还包括电压控制单元，电压控制单元通过对第一开关电路的输入电压或输出电压进行调整，以控制第二开关电路的输入电压在预设范围内，将第二开关电路的输出电压作为开关电源的输出电压输出，从而提高开关电源的转换效率。其中，预设范围包括使第二开关电路的转换效率高于所需值的第二开关电路的输入电压范围，可选的，预设范围采用转换效率最高的第二开关电路的输入电压范围；电压控制单元可以对第一开关电路的输入电压进行控制；级联是指两个开关电路以一定的方式连接，例如串联、并联或者串联与并联结合等。
可选地，电压控制单元包括输入电压控制单元。请参见图3，图3为本实施例提供的开关电源结构示意图。图3中，该开关电源包括第一开关电路31、第二开关电路32、输入电压控制单元33、输入电源34以及三个电解电容35、36和37；第一开关电路31输入端的正负极之间电连接一个电解电容35用于滤波，第二开关电路32输入端的正负极之间电连接另一个电解电容36用于滤波，第一开关电路31与第二开关电路32的输出端均与第三个电解电容37电连接用于滤波；第一开关电路31的输入端与第二开关电路32的输入端串联后电连接至输入电源34的输入端，第一开关电路31的输出端与第二开关电路32的输出端并联后电连接至开关电源的输出端；同时，输入电压控制单元33的输入端与第一开关电路31的输入端负极电连接，输入电压控制单元33的输出端与第一开关电路31的开关管(图3中未示出)电连接，用于对第一开关电路31的输入电压进行调整，进而控制第二开关电路32的输入电压位于使第二开关电路32具有较高转换效率的输入电压范围内，使得第二开关电路32最终的输出电压为所需值。
第一开关电路31和第二开关电路32可采用电源拓扑，如buck、升压变换电路(boost)、升降压变换电路(buckboost)、正激、反激、推挽或桥式等电路。可选地，第二开关电路32还可以包括不稳压或半稳压控制的电路，其中，半稳压结构的电路能在限定范围内实现输出电压的稳压，此范围内开关电源的转换效率较高。不稳压结构的电路的占空比固定，具有较高的转换效率。可选地，第一开关电路31与第二开关电路32均为隔离型电路，因此开关电源为隔离型 电源。在输入电压控制单元33通过调整第一开关电路31的输入电压，以控制第二开关电路32的输入电压处于使开关电源具有较高转换效率的输入电压范围内的情况下，对于隔离型开关电源，无需从该开关电源的副边经过光耦等隔离器件反馈输出电压，对开关电源的体积控制和寿命都带来好处。第一开关电路31可由多个电源拓扑并联、串联或者串并结合构成，相应的，第二开关电路32同样可由多个电源拓扑串联、并联或串并结合构成。例如是下述至少一种情况，当第一开关电路31包括至少两个电源拓扑时，各电源拓扑并联；当第二开关电路32包括至少两个电源拓扑时，各电源拓扑并联。
图3所示的开关电源采用第一开关电路31与第二开关电路32的输入端串联、输出端并联的架构，使得转换效率较低的第一开关电路31仅承担了一小部分的输出功率，从而提高了开关电源整体的转换效率。同时，由于第一开关电路31采用输入电压前馈控制，通过输入电压控制单元33控制第二开关电路32的输入电压，使得第二开关电路32的输入电压工作在较高转换效率的输入电压范围内。
可选地，请参见图4，图4为本实施例提供的另一开关电源结构示意图。图4中，开关电源包括第一开关电路41、第二开关电路42、输入电源45以及三个电解电容46、47和48，第一开关电路41输出端的正负极之间连接一个电解电容46用于滤波，第二开关电路42输入端的正负极之间连接另一个电解电容47用于滤波，第一开关电路41的输入端与第二开关电路42的输出端均与第三个电解电容48电连接用于滤波；第一开关电路41的输入端与第二开关电路42的输出端串联后连接至开关电源的输出端，第一开关电路41的输出端与第二开关电路42的输入端串联后连接至输入电源45的输入端。
在本实施例中的开关电源中，对第二开关电路42的输入电压存在两种控制方式：
在第一种控制方式中，第一开关电路41采用输入电压(即第二开关电路42输出电压)前馈的方式直接控制第二开关电路42最终的输出电压为所需值，同时，对于隔离型开关电源，此控制方式亦可避免从开关电源的副边经过光耦等隔离器件反馈输出电压，对开关电源的体积控制和寿命都带来好处。
在第一种控制方式中，第一开关电路41可采用稳压型开关电路，以反馈的方式控制第二开关电路42的输入电压位于第二开关电路42具有较高转换效率的输入电压范围内，使得第二开关电路42的输出电压为所需值，也即第一开关 电路41的输出端通过与第二开关电路42的输入端串联，保证第二开关电路42的输入电压位于第二开关电路42具有较高转换效率的输入电压范围内。
对于第一种控制方式，图4中还包括输入电压控制单元43，通过该输入电压控制单元43实现输入电压前馈控制。输入电压控制单元43的输入端与第一开关电路41的输入端电连接，输入电压控制单元43的输出端与第一开关电路41的开关管(图中未示出)电连接，用于对第一开关电路41的输入电压进行调整，进而控制第二开关电路42的输入电压工作在较高转换效率的输入电压范围内，使得第二开关电路42最终的输出电压为所需值。上述开关管可以为金属氧化物半导体场效应晶体(metal oxide semiconductor，MOS)，还可以采用其他场效应晶体管。下面将以MOS管为例对本实施例进行说明。
对于第二种控制方式，图4中还包括输出电压控制单元44，通过该输出电压控制单元44实现输出电压反馈控制。输出电压控制单元44的输入端与第一开关电路41的输出端电连接，输出电压控制单元44的输出端与第一开关电路41的开关管(图中未示出)电连接，用于对第一开关电路41的输出电压进行调整，进而控制第二开关电路42的输入电压工作在较高转换效率的输入电压范围内，使得第二开关电路42的输入电压在预设范围内。
可选地，图4中第一开关电路41需要进行双象限(bidirectional)工作，即第一开关电路41的输出电压和输出电流可以是反向的，电源能量可以在第一开关电路41的输入端和输出端之间双向传递。在此连接方式下，可保证电源能量还是从输入电源端(左)向负载端(右)传送。采用同步整流电路可实现双象限工作，如同步buck，boost及各种同步整流的桥式电路。第二开关电路42可采用buck、boost、buckboost、正激、反激、推挽、或桥式等电路，也可采用半稳压或不稳压控制的高效电路。同时，第一开关电路41可由多个电源拓扑并联、串联或者串并结合构成，相应的，第二开关电路42同样可由多个电源拓扑串联、并联或串并结合构成，例如是下述至少一种情况，当第一开关电路41包括至少两个电源拓扑时，各电源拓扑并联；和当第二开关电路42包括至少两个电源拓扑时，各电源拓扑并联。可选地，当开关电源为隔离型电源时，通过输入电压控制单元43的前馈控制方式，同样可避免使用光耦等隔离器件，从而减小开关电源体积、增加使用寿命。
此外，本实施例还提供了一种电子设备，包括前述的开关电源。
本实施例提供的开关电源，通过级联的第一开关电路与第二开关电路级联， 以功率分担的方式承担开关电源的输出功率，使转换效率相对较低的第一开关电路仅承担很小部分的输出功率，从而提高了整个开关电源的的转换效率。通过电压控制单元对第一开关电路的电压进行控制，使得第二开关电路的输入电压处于使第二开关电路具有较高转换效率的输入电压范围内，从而控制第二开关电路的输出电压为所需值，提升开关电源的转换效率。对于隔离型开关电源，无需从开关电源的副边经过光耦等隔离器件反馈输出电压，对开关电源的体积控制和寿命都带来好处。
实施例二
基于实施例一的开关电源，本实施例以图3示出的开关电源为基础，对本实施例进行解释，也即以第一开关电路与第二开关电路的输入端串联，输出端并联的连接方式对本实施例进行说明。
请参见图5，图5为本实施例提供的第二开关电路结构示意图，第二开关电路为LLC谐振电路，该LLC谐振电路包括谐振电感51、谐振电容52、励磁电感53、变压器54、输出电容56、变压器54原边(位于图5中变压器54的左侧)的两个MOS管(也即开关管55)、变压器54副边(位于图5中变压器54的右侧)的两个MOS管57和58以及与两个MOS管57和58分别并联的二极管。其中，谐振电感51和谐振电容52串联，励磁电容53与变压器54的原边并联，谐振电容52与变压器54的同名端连接，开关管55串联在输入电源输入端的正负极之间，谐振电感51输入端与开关管55中上一MOS管551的输出端连接；变压器54副边两端分别连接一MOS管57和58，在这两个MOS管57和58的漏极和源极之间分别并联一个二极管以防止MOS管57和58被反向击穿；这两个MOS管57和58的漏极串联并与电容56的正极连接，输出电容56的负极连接至变压器54副边下一线圈541的同名端并与开关电源输出端连接。
在LLC谐振电路中，当开关管的开关频率工作在由谐振电感51和谐振电容52形成的谐振频率点时，能实现变压器54的原边及副边的整流电路的软开关，开关损耗能降至最低，并且原边的电压和电流波形同步，电源能量的传输效率最高，因此能实现很高的电源转换效率。开关频率可以做到很高，电源的功率密度得到有效提升。LLC谐振电路最高效率在谐振点实现，此时谐振电路增益为1，LLC谐振电路的输入电压和输出电压的比例为变压器54的原边和副边匝数比N∶1。在LLC谐振电路的输入电压范围较宽时，LLC谐振电路的开关频率需要在较大的范围内变化，以使LLC谐振电路达到需要的增益，此时原边电 压和电流的波形不再同步，能量传送效率较低(不考虑功率因素)，存在能量回馈现象，电流均方根值RMS(root meam square，RMS)较高，导致导通损耗增加，电源能量的传输效率降低。
可选地，请参见图6，图6为本实施例提供的隔离型开关电源结构示意图，该隔离型结构包括第一开关电路61、第二开关电路62、输入电压控制单元63、以及三个电解电容，其中，第二开关电路62采用图5中LLC谐振电路，在图6中以变压器代表LLC谐振电路，对于该LLC谐振电路的结构，请参见图5中的相关分析，这里不再赘述。第一开关电路61采用反激式隔离电路，该反激式隔离电路中包括变压器611、位于变压器611原边的一个MOS管612、位于变压器611副边的一个MOS管613以及该MOS管613上电连接的二极管614；变压器611原边非同名端电连接MOS管612的漏极，该MOS管612的栅极与输入电压控制单元63电连接，MOS管612的源极与一个电解电容负极电连接，该电解电容并联在变压器611原边后电连接至输入电源的输入端，输入电压控制单元63的输入端与该电解电容的负极电连接；变压器611副边的同名端与MOS管613的漏极电连接，在该MOS管613的漏极与源极之间并联二极管614以防MOS管613被反向击穿。第二开关电路62的输入端与第一开关电路61的输入端串联后连接至输入电源的输入端，第二开关电路62的输出端与第一开关电路61的输出端并联后电连接至另一电解电容，该电解电容与开关电源的输出端电连接，第二开关电路62的输入端与输入电压控制单元63的输入端电连接。
在上述隔离型结构中，反激式隔离电路通过输入电压前馈的控制方式，控制LLC谐振电路的输入电压为N*Vo，其中Vo为所需的开关电源的输出电压，N为LLC谐振电路的输入输出电压增益，如上所述，当此LLC谐振电路工作在谐振点时，N即为变压器611的原边和副边绕组匝数比N∶1。此时LLC谐振电路可工作在最高转换效率点，输入电压Vin超过N*Vo的部分由反激电路的输入电压调节。控制方法包括：当输入LLC谐振电路的输入电压高于N*Vo时，反激式隔离电路通过减小占空比，进而减小功率输出，促使LLC谐振电路部分的输出功率增加，输入电容放电，LLC谐振电路的输入电压下降。
由于反激式隔离电路与LLC谐振电路的输入端为串联结构，稳态时这两者的输入电流是相等的，所以反激式隔离电路与LLC谐振电路的输入功率与各自的输入电压成正比，当Vin与N*Vo接近时，反激式隔离电路的输入电压远小于LLC谐振电路，即转换效率较低的反激式隔离电路仅负责一小部分的功率，整 个开关电源的输出功率大部分由工作在谐振点的LLC谐振电路提供，因此开关电源整体的转换效率能得到提高。此外，LLC谐振电路在谐振点工作能实现LLC谐振电路中变压器原边及副边的软开关，利于提高开关频率，减小开关电源的体积，进而提高功率密度；而且本实施例中对反激式隔离电路采用输入电压前馈的控制方式，没有传统反激式隔离电路输出电压反馈所需的光耦等隔离器件，可以提高整体电源的功率密度。
可选地，请参见图7，图7为本实施例提供的非隔离型开关电源结构示意图，该非隔离型电路包括第一开关电路71、第二开关电路72、输入电压控制单元73以及三个电解电容；其中，第二开关电路72采用与图5一致的LLC谐振电路，在图7中以变压器表示LLC谐振电路，对于该LLC谐振电路的结构，请参见对图5的分析，这里不再赘述。第一开关电路71采用非隔离型buck电路，该非隔离型buck电路包括两个MOS管(即开关管711)以及电感712。在开关管711中，一个MOS管7111的源极与另一MOS管7112的漏极电连接，并电连接至电感712的正极。第二开关电路72输入端的正负极之间并联一个电解电容74进行滤波，第一开关电路71输入端的正负极之间并联另一电解电容75进行滤波，第一开关电路71的输入端与第二开关电路72的输入端串联后连接至输入电源的输入端，输入电压控制单元73的输入端与电解电容75的正极连接，且与第二开关电路72的输入端连接；输入电压控制单元73的输出端与两个MOS管7111和7112的栅极电连接，其中MOS管7111的漏极与输入电压控制单元73的输入端电连接，第一开关电路71输出端与第二开关电路72输出端并联并连接至第三个电解电容76，该电解电容76电连接至开关电源的输出端。
由于非隔离型buck电路不包括变压器带来的输入输出隔离特性，非隔离型buck电路的输入电压负端需要接地。LLC谐振电路具有隔离特性，其输入电压的正端电连接输入电源的正端，Vin为输入电源的输入电压值。非隔离型buck电路采用输入电压前馈方式，控制非隔离型buck电路的输入电压为Vin-N*Vo，其中，Vo为所需的开关电源的输出电压。此时LLC谐振电路的输入电压为N*Vo，其中N为LLC谐振电路的输入输出电压增益。控制方式为，当非隔离型buck电路的输入电压较高时，增大占空比，非隔离型buck电路传递能量增加，非隔离型buck电路的电解电容放电，输入电压降低。
可选地，请参见图8，图8为本实施例提供的另一非隔离型开关电源结构示意图，该非隔离型开关电源包括第一开关电路81、第二开关电路82、输入电压 控制单元83以及三个电解电容。其中，第二开关电路82采用的非隔离电路，为图8中示出的N＝2的半压型开关电容电路，此电路能实现高效的Vo＝1/2Vin的非隔离转换，Vo为所需的开关电源的输出电压，配合隔离的第一开关电路81，形成图8的非隔离型开关电源。第一开关电路81采用图6中第一开关电路61的电路结构，即采用反激式隔离电路，具体电路结构这里不再赘述，请参见图6关于反激式隔离电路的描述。第一开关电路81的输入端与第二开关电路82的输入端串联后电连接至输入电源的输入端，输入电压控制单元83的输入端与第一开关电路81输入端的负极电连接，输出端与第一开关电路81中的MOS管(即开关管)栅极电连接，第一开关电路81的输入端正负极之间并联一个电解电容84，第二开关电路82输入端正负极之间并联另一电解电容85，第一开关电路81与第二开关电路82的输出端并联并连接至另一电解电容86，该电解电容86连接至开关电源的输出端。对于图8中的非隔离型开关电源的控制方式与图6类似，故这里不再赘述。
通过本实施例提供的各电路图，开关电源的输入端串联和输出端并联的架构，使得效率较低的第一开关电路仅承担一部分的功率，使得整个开关电源的转换效率较高，同时，通过输入电压控制单元对第一开关电路的输入电压进行调整，使得第二开关电路的输入电压工作在较高转换效率的输入电压范围内，提高了开关电源的转换效率。此外，对于隔离型开关电源，可以采用输入控制电路前馈方式，无需从该开关电源的副边经过光耦等隔离器件反馈输出电压，利于减小开关电源的体积和增加使用寿命。
实施例三
基于实施例一的开关电源，本实施例以图4示出的开关电源为基础，对本实施例进行解释，也即以第一开关电路的输出端与第二开关电路的输入端电连接，第一开关电路的输入端与第二开关电路的输出端电连接，描述如下。
请参见图9，图9为本实施例提供的隔离型开关电源结构示意图，该隔离型开关电源包括第一开关电路91、第二开关电路92、输入电压控制单元93以及三个电解电容。其中，第二开关电路92由前述LLC谐振电路组成，图9中以变压器表示，对于LLC谐振电路的结构，这里不再赘述。第一开关电路91采用传统全桥同步整流电路，该全桥同步整流电路包括变压器911、电感912、变压器911副边两个MOS管913和914以及MOS管913和914上的二极管915和916、变压器911原边四个MOS管917、918、919和920以及这四个MOS管上的二 极管(即图9中变压器911左边为副边、右边为原边)，变压器911原边两端之间并联四个MOS管，其中，MOS管917和919的漏极均与变压器911原边同名端连接，MOS管918和920的源极均与变压器911原边非同名端连接；MOS管917的源极与MOS管918的漏极连接，MOS管919的源极与MOS管920的漏极连接；变压器911副边上一线圈921的非同名端与MOS管913的漏极连接，变压器911副边中下一线圈922的非同名端与MOS管914的漏极连接；变压器911副边中的MOS管913的漏极和源极之间并联一个二极管915，MOS管914的漏极和源极之间并联一个二极管916，以防止MOS管913和914被反向击穿，MOS管913和914的源极连接；电感912的负极与变压器911副边中上下两个线圈921和922之间电连接，电感912的正极与输入电源94电连接。输入电压控制单元93的输入端与第一开关电路91的输入端并联，与第二开关电路92的输出端串联，输入电压控制单元93的输出端与第一开关电路91的变压器原边连接的四个MOS管电连接，第一开关电路91输出端与第二开关电路92的输入端串联后连接至输入电源94的输入端，第二开关电路92的输出端与第一开关电路91的输入端电连接并连接至一个电解电容95，该电解电容95与开关电源的输出端电连接，且在第一开关电路91输出端的正负极之间并联另一电解电容96，在第二开关电路92输入端正负极之间并联另一电解电容97。
在图9中的隔离型开关电源中，LLC谐振电路的输出即最终开关电源输出电压连接全桥同步整流电路的原边输入端，全桥同步整流电路的副边输出端与LLC谐振电路的输入端串联后连接至输入电源94。全桥同步整流电路的副边采用MOS管组成的同步整流电路，可保证电流的双向流动。第一开关电路91采用输入电压(即第二开关电路92的输出电压Vo，Vo为所需的开关电源的输出电压)前馈的方式，控制Vo为所需值。控制方式为：当Vo高于所需值时，第一开关电路91增大占空比，增大的能量从原边向副边的传递，第一开关电路91的输出电压增加，使得第二开关电路92的输入电压降低，进而降低第二开关电路的输出电压Vo，使得开关电源最终的输出电压为所需值。
本实施例提供的开关电源，采用输入电压前馈的方式，控制第二开关电路的输入电压工作在较高转换效率的输入电压范围内，从而提升开关电源整体的转换效率，同时，采用隔离型开关电源，在输入电压前馈的控制方式下，亦可避免使用光耦等隔离器件增大开关电源的体积，减小开关电源的使用寿命。
实施例四
本实施例以实施例一为基础，提供一种开关电源控制方法，该控制方法与实施例提供的开关电源装置对应，故本实施例将不再对开关电源结构做详细说明。本实施提供的开关电源控制方法包括：
利用电压控制单元调整第一开关电路的输入电压或输出电压以控制所述第二开关电路的输入电压在预设范围内；
将第二开关电路的输出电压作为所述开关电源的输出电压输出；
其中，所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联；所述第一开关电路与第二开关电路以功率分担的方式共同承担开关电源的输出功率；所述第一开关电路所承担的开关电源的输出功率小于所述第二开关电路所承担的输出功率，所述第一开关电路的转换效率小于所述第二开关电路的转换效率。
一种实施方式中，将第一开关电路的输入端与第二开关电路的输出端串联后连接至开关电源的输出端，将第一开关电路的输出端与第二开关电路的输入端串联后连接至开关电源的输入端，将电压控制单元的输入端与开关电源的输出端连接，将电压控制单元的输出端与第一开关电路的开关管连接，其中，第一开关电路包括同步整流电路；针对该开关电源结构，可采用如下开关电源的控制方式：
电压控制单元通过调整第一开关电路的输入电压控制第二开关电路的输入电压在预设范围内，将第二开关电路的输出电压作为开关电源的输出电压输出。
一种实施方式中，将第一开关电路的输入端与第二开关电路的输出端串联后连接至开关电源的输出端，将第一开关电路的输出端与第二开关电路的输入端串联后连接至开关电源的输入端，将电压控制单元的输入端与开关电源的输入端连接，将电压控制单元的输出端与第一开关电路的开关管连接，其中，第一开关电路包括同步整流电路；针对该开关电源结构，可采用如下开关电源的控制方式：
电压控制单元通过调整第一开关电路的输出电压控制第二开关电路的输入电压在预设范围内，将第二开关电路的输出电压作为开关电源的输出电压输出。
另一种实施例方式中，将第一开关电路的输入端与第二开关电路的输入端串联后连接至开关电源的输入端，将第一开关电路的输出端与第二开关电路的输出端并联后连接至开关电源的输出端，将电压控制单元的输入端与开关电源的输入端连接，将电压控制单元的输出端与第一开关电路的开关管连接；针对 该开关电源结构，可采用如下开关电源控制方式，具体如下：
电压控制单元通过调整第一开关电路的输入电压控制第二开关电路的输入电压在预设范围内，将第二开关电路的输出电压作为开关电源的输出电压输出。
前述预设范围包括转换效率较高的输入电压范围，可选的，预设范围采用转换效率最高的输入电压范围；前述级联是指两个开关电源的输入、输出以一定的方式连接，如串联、并联、串联与并联结合等。
可选地，第一开关电路和第二开关电路均可采用电源拓扑，如buck、boost、buckboost、正激、反激、推挽或桥式等电路。第二开关电路还可采用不稳压或半稳压控制的电路，其中，半稳压结构的电路能在限定范围内实现输出电压的稳压，此范围内电源的转换效率较高，不稳压结构的电路占空比固定，具有较高的转换效率。
当第一开关电路和第二开关电路均为隔离型电路时，开关电源为隔离型开关电源；在输入电压控制单元通过调整第一开关电路的输入电压，以控制第二开关电路的输入电压工作在较高效率的输入电压范围内的情况下，对于隔离型开关电源，无需从副边经过光耦等隔离器件反馈输出电压，对电源的体积控制和寿命都带来好处。
此外，当第一开关电路采用输入电压前馈控制方式时，通过输入电压控制单元控制第一开关电路的输入电压，使得第二开关电路的输入电压工作在较高效率的输入电压范围内，从而提升整个开关电源的转换效率。同时，当第一开关电路采用输出电压馈控制方式时，通过输出电压控制单元控制第一开关电路的输出电压，使得第二开关电路的输入电压工作在较高效率的输入电压范围内，从而提升整个开关电源的转换效率。
通过本实施例提供的开关电源控制方法，有效的通过前馈或反馈的方式控制第二开关电路的输入电压工作在较高效率的输入电压范围内，使得开关电源最终的输出电压为所需值，从而提高开关电源的转换效率。
工业实用性
本公开提供一种开关电源、电子设备及开关电源控制方法，包括级联的第一开关电路与第二开关电路，通过电压控制单元对第一开关电路的输入电压或输出电压进行调整，使得第二开关电路的输入电压工作在预设范围内，然后将第二开关电路的输出电压作为开关电源的输出电压输出，从而提高开关电源的 转换效率。

Claims (11)

  1. 一种开关电源，包括：级联的第一开关电路与第二开关电路，并以功率分担的方式共同承担开关电源的输出功率；还包括电压控制单元，与所述第一开关电路电连接，所述电压控制单元设置为：通过对所述第一开关电路的输入电压或输出电压进行调整，以控制所述第二开关电路的输入电压在预设范围内，将所述第二开关电路的输出电压作为开关电源的输出电压；
    其中，所述第一开关电路所承担的开关电源的输出功率小于所述第二开关电路所承担的输出功率，所述第一开关电路的转换效率小于所述第二开关电路的转换效率。
  2. 如权利要求1所述的开关电源，其中，所述第一开关电路的输入端与所述第二开关电路的输入端串联且电连接至开关电源的输入端，所述第一开关电路的输出端与所述第二开关电路的输出端并联且电连接至开关电源的输出端；所述电压控制单元包括输入电压控制单元，所述输入电压控制单元设置为：通过对所述第一开关电路的输入电压进行调整，以控制所述第二开关电路的输入电压在预设范围内。
  3. 如权利要求1所述的开关电源，其中，所述第一开关电路的输入端与所述第二开关电路的输出端串联且电连接至开关电源的输出端，所述第一开关电路的输出端与所述第二开关电路的输入端串联且电连接至开关电源的输入端；所述电压控制单元包括输入电压控制单元，所述输入电压控制单元设置为：通过对所述第一开关电路的输入电压进行调整，以控制所述第二开关电路的输入电压在预设范围内；所述第一开关电路包括同步整流电路。
  4. 如权利要求1所述的开关电源，其中，所述第一开关电路的输入端与所述第二开关电路的输出端串联且电连接至开关电源的输出端，所述第一开关电路的输出端与所述第二开关电路的输入端串联且电连接至开关电源的输入端；所述电压控制单元包括输出电压控制单元，所述输出电压控制单元通过对所述第一开关电路的输出电压进行调整，以控制所述第二开关电路的输入电压在预设范围内；所述第一开关电路包括同步整流电路。
  5. 如权利要求1-4任一项所述的开关电源，其中，所述第一开关电路和第二开关电路分别包括至少一个电源拓扑。
  6. 如权利要求5所述的开关电源，其中，当所述第一开关电路和第二开关电路分别包括至少两个电源拓扑时，所述第一开关电路中的所述至少两个电源拓扑并联，所述第二开关电路中的所述至少两个电源拓扑并联。
  7. 一种电子设备，包括如权利要求1-6任一项所述的开关电源。
  8. 一种开关电源控制方法，包括：
    利用电压控制单元调整第一开关电路的输入电压或输出电压以控制所述第二开关电路的输入电压在预设范围内；
    将第二开关电路的输出电压作为所述开关电源的输出电压输出；
    其中，所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联；所述第一开关电路与第二开关电路以功率分担的方式共同承担开关电源的输出功率；所述第一开关电路所承担的开关电源的输出功率小于所述第二开关电路所承担的输出功率，所述第一开关电路的转换效率小于所述第二开关电路的转换效率。
  9. 如权利要求8所述的方法，其中所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联包括：所述第一开关电路的输入端与所述第二开关电路的输入端串联且电连接至开关电源的输入端，所述第一开关电路的输出端与所述第二开关电路的输出端并联且电连接至开关电源的输出端，所述电压控制单元的输入端与开关电源的输入端电连接，电压控制单元的输出端与第一开关电路的开关管电连接。
  10. 如权利要求8所述的方法，所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联包括：
    所述第一开关电路的输入端与所述第二开关电路的输出端串联且电连接至开关电源的输出端，所述第一开关电路的输出端与所述第二开关电路的输入端并联且电连接至开关电源的输入端，所述电压控制单元的输入端与开关电源的输出端连接，电压控制单元的输出端与第一开关电路的开关管电连接。
  11. 如权利要求8所述的方法，所述电压控制单元与所述第一开关电路电连接，所述第一开关电路与所述第二开关电路级联包括：
    所述第一开关电路的输入端与所述第二开关电路的输出端串联且电连接至开关电源的输出端，所述第一开关电路的输出端与所述第二开关电路的输入端并联且电连接至开关电源的输入端，所述电压控制单元的输入端与开关电源的输入端连接，电压控制单元的输出端与第一开关电路的开关管电连接。
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