WO2021248333A1 - 一种降压电路、降压装置和电路控制方法 - Google Patents

一种降压电路、降压装置和电路控制方法 Download PDF

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Publication number
WO2021248333A1
WO2021248333A1 PCT/CN2020/095187 CN2020095187W WO2021248333A1 WO 2021248333 A1 WO2021248333 A1 WO 2021248333A1 CN 2020095187 W CN2020095187 W CN 2020095187W WO 2021248333 A1 WO2021248333 A1 WO 2021248333A1
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Prior art keywords
voltage
switching device
circuit
freewheeling
inductor
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PCT/CN2020/095187
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English (en)
French (fr)
Inventor
赵密
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华为数字能源技术有限公司
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Application filed by 华为数字能源技术有限公司 filed Critical 华为数字能源技术有限公司
Priority to CN202080005547.4A priority Critical patent/CN114072999A/zh
Priority to EP20940440.9A priority patent/EP4156487A4/en
Priority to PCT/CN2020/095187 priority patent/WO2021248333A1/zh
Publication of WO2021248333A1 publication Critical patent/WO2021248333A1/zh
Priority to US18/063,527 priority patent/US20230106017A1/en

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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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection

Definitions

  • This application relates to the field of circuit technology, and in particular to a step-down circuit, a step-down device, and a circuit control method.
  • the buck circuit can reduce a higher input voltage to a lower voltage that meets the requirements of the subsequent load for output, and has a wide range of applications in various fields.
  • the buck step-down circuit includes a main control switch, a diode or a synchronous rectifier switch, an inductor and a capacitor. During operation, the main control switch is turned on at a certain frequency and duty cycle, so that the buck step-down circuit outputs a stable low voltage.
  • the input voltage passes through the short-circuited switch and inductor string to the output port.
  • the output port voltage is equal to the input voltage, which is higher than the design value of the subsequent load, which may cause damage to the subsequent load.
  • the rated voltage of the CPU of consumer electronics is 1.8V.
  • the CPU may be over-voltage and burned.
  • 72V voltage is directly connected to a device with a rated voltage of 48V, it may trigger input overvoltage and device failure.
  • the present application provides a step-down circuit, a step-down device, and a circuit control method, which can realize effective overvoltage protection.
  • a step-down circuit including: a first switch, a second switching device, a first freewheeling device, a second freewheeling device, an inductor, a first capacitor, and an overvoltage protection OVP module, which is characterized by It is: the first switching device and the first free-wheeling device form a bridge arm; the first end of the inductor is connected to the midpoint of the bridge arm, and the second end of the inductor is connected to the second switching device; the first end of the second free-wheeling device Connected to the second end of the inductor; the first end of the first capacitor is connected to the second switching device, and the first capacitor is connected in parallel with the OVP module and the load of the step-down circuit; the OVP module is used to detect the output voltage of the step-down circuit, The output voltage of the step-down circuit is the input voltage of the load. When the output voltage is greater than the protection reference voltage, the OVP module controls the first switching device and the second switching device to turn off.
  • the OVP module when the OVP module detects that the output voltage exceeds the protection reference voltage, it will disconnect the first switching device and the second switching device to prevent the output voltage from continuing to rise. Moreover, in the aforementioned step-down circuit, the first switching device and the second switching device are not directly connected in series, which reduces the possibility of simultaneous failure of the first switching device and the second switching device due to overcurrent.
  • the first freewheeling device is a third switching device
  • the circuit further includes: an overcurrent protection OCP module; the OCP module is connected to the second end of the input power source, and the OCP module is used to detect the input current When the input current is greater than the protection reference current, the OCP module controls the first switching device, the second switching device and the third switching device to turn off.
  • the first freewheeling device is a first diode.
  • the first freewheeling device is the first diode
  • the possibility of short circuit between the first switching device and the first diode is low.
  • No OCP module is needed, which simplifies the circuit.
  • the step-down circuit further includes a fault confirmation module, the first end of the fault confirmation module is connected to the second end of the inductor, and the second end of the fault confirmation module is connected to the first end of the input power supply. Connected; the fault confirmation module is used to determine whether the first switching device is short-circuited.
  • the fault confirmation module determines that the first switching device is not short-circuited; when the voltage at the second end of the inductor When the voltage difference with the first terminal of the input power source is less than or equal to the first threshold, the fault confirmation module determines that the first switching device is short-circuited.
  • the OVP module When the OVP module detects that the output voltage is greater than the protection reference voltage, it controls the first switching device and the second switching device to turn off, or when the OCP module detects that the input current is greater than the protection reference current, it controls the first, second, and third switching devices to turn off When turned on, neither of these two modules can confirm whether there is a short circuit in the step-down circuit and whether it can be restored to work.
  • the fault confirmation module it can be determined whether the first switching device of the step-down circuit is short-circuited, so as to determine whether the step-down circuit can resume operation, and the safety of the step-down circuit is further improved.
  • the second freewheeling device is a second capacitor, and the second end of the second capacitor is grounded; or the second freewheeling device is a second diode, and the The second end is connected to the first end of the input power source.
  • the step-down circuit further includes a third freewheeling device; when the second freewheeling device is a second capacitor, the third freewheeling device is a second diode; or, when the first freewheeling device is a second capacitor, When the second freewheeling device is the second diode, the third freewheeling device is the second capacitor.
  • a circuit control method includes: determining that the output voltage of the circuit is greater than the protection reference voltage, or determining that the input current of the circuit is greater than the protection reference current; and turning off the first switching device and the second switching device.
  • the circuit includes: a first switching device, a second switching device, a first freewheeling device, a second freewheeling device, an inductor, and a first capacitor; the first switching device and the first freewheeling device form a bridge arm; The first end is connected to the midpoint of the bridge arm, the second end of the inductor is connected to the second switching device; the first end of the second freewheeling device is connected to the second end of the inductor; the first end of the first capacitor is connected to the second The switching device is connected, and the first capacitor is connected in parallel with the load of the circuit; the output voltage of the circuit is the input voltage of the load, and the input current of the circuit is the current of the loop where the input power supply of the circuit is located.
  • Over-voltage detection and over-current detection are combined.
  • the circuit will realize over-voltage protection and disconnect the first and second switching devices; when the input side current is detected to rise, but the output voltage has not exceeded the protection
  • the first and second switches can still be disconnected to realize effective protection measures to avoid excessively high output side voltage.
  • the combination of the two detection measures improves the safety of the circuit.
  • the method further includes: determining whether the first switching device is short-circuited; when it is determined that the first switching device is short-circuited, turning off the second switching device; when it is determined that the first switching device is not short-circuited, turning on the second switching device Two switching devices.
  • the second switching device can be turned on after the output side voltage drops below the protection reference voltage, so that the circuit resumes normal operation.
  • determining whether the first switching device is short-circuited includes: determining the difference between the first voltage and the voltage of the input power source, the first voltage being the voltage of the second terminal of the inductor; When the difference between the voltage of the power source is greater than the first threshold, it is determined that the first switching device is not short-circuited; when the difference between the first voltage and the voltage of the input power source is less than or equal to the first threshold, it is determined that the first switching device is short-circuited.
  • the method before determining the difference between the first voltage and the voltage of the input power supply, the method further includes: determining a sampling voltage of the first voltage, and determining the first voltage according to the sampling voltage of the first voltage .
  • determining that the output voltage of the circuit is greater than the protection reference voltage includes: determining that the output voltage is greater than the second threshold, determining that the output voltage of the circuit is greater than the protection reference voltage; or determining that the sampling voltage of the output voltage is greater than the third Threshold, to determine that the output voltage of the circuit is greater than the protection reference voltage.
  • determining that the input current of the circuit is greater than the protection reference current includes: determining that the second voltage corresponding to the input current is greater than a fourth threshold, and determining that the input current of the circuit is greater than the protection reference current.
  • a voltage reduction device which includes the voltage reduction circuit of the foregoing first aspect and any possible implementation manner of the first aspect.
  • Figure 1 is a schematic diagram of an existing overvoltage protection scheme for a step-down circuit
  • Fig. 2 is a schematic diagram of a step-down circuit according to an embodiment of the present application.
  • FIG. 3 is a schematic diagram of another step-down circuit according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of another step-down circuit according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram of another step-down circuit according to an embodiment of the present application.
  • FIG. 6 is a schematic flowchart of a circuit control method according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of a circuit corresponding to a circuit control method according to an embodiment of the present application.
  • the input voltage of 12V needs to be reduced to 3.3V, or the input voltage of 3.3V needs to be reduced to 1.8V; for example, in the secondary power supply of a communication system, the bus voltage of 48V needs to be reduced to The voltage value required by the load; for example, the lithium battery power conversion board needs to convert a lithium battery larger than 57V into the 48V voltage required by the communication system.
  • a step-down (buck) circuit can reduce a higher input voltage to a lower voltage that meets the requirements of the subsequent load for output, and has a wide range of applications in the above-mentioned energy conversion scenarios.
  • the input high voltage will be connected to the output through the inductor, causing the output to be over-voltage, damaging the subsequent electrical equipment, and endangering the safety of the circuit. Therefore, overvoltage protection measures are needed to ensure the safety of the step-down circuit when the main control switch fails.
  • FIG. 1 is a schematic diagram of an existing step-down circuit protection scheme.
  • the step-down circuit includes: a switching device 101, a switching device 102, a switching device 103, an inductor 104, a capacitor 105, and an overvoltage protection (OVP) module 106.
  • the switching device 101 is a main control switch, and the switching device 102 is a freewheeling switch.
  • the switching device 101 is turned on at an appropriate frequency and duty cycle, so that the load can obtain a stable lower voltage Vo that is lower than the input voltage Vin.
  • the OVP module 106 is connected in parallel at the load, and the switching device 103 is connected in series with the switching device 101, and the switching device 103 is used as a backup switch.
  • the OVP module detects that the output voltage Vo rises to the overvoltage protection point, and the switching device 103 as a backup switch is turned off to prevent the input voltage from being transmitted to the output.
  • the main control switch 101 fails due to overcurrent, a relatively large current will also flow through the backup switch 103, so the main control switching device 101 and the backup switching device 103 may fail at the same time. After the main control switching device 101 and the backup switching device 103 fail at the same time, the overvoltage protection cannot be realized.
  • the freewheeling switching device 102 uses a synchronous rectification switch, when the switching device 101 is short-circuited and the switching device 102 is turned on, the bridge arm circuit composed of the switching device 101 and the switching device 102 will flow through a relatively large short circuit. The current further induces subsequent failures. For example, if the input bus is pulled down due to overcurrent, the switching device 102 further fails due to an overcurrent short circuit.
  • the input bus is short-circuited, and other devices on the same bus are powered down.
  • the switching device 102 fails due to an open circuit due to overcurrent, which causes the input voltage to be directly connected to the output, causing the output to be overvoltage.
  • the step-down circuit provided by the embodiment of the present application can realize effective over-voltage protection of the step-down circuit and enhance the safety of the circuit.
  • step-down circuit of the embodiment of the present application will be described in detail with reference to FIGS. 2 to 5.
  • Fig. 2 is a schematic diagram of a step-down circuit according to an embodiment of the present application.
  • the step-down circuit includes: a first switching device, a second switching device, a first freewheeling device, a second freewheeling device, an inductor, a first capacitor, and an OVP module.
  • the first switching device is S1
  • the second switching device is S2
  • the inductance is L1
  • the first capacitor is C1.
  • the first freewheeling device is the third switching device S3, and the second freewheeling device is the second capacitor C2.
  • S1 and S3 form the switch bridge arm.
  • the first end of the inductor L1 is connected to the midpoint of the switch bridge arm, and the second end is connected to the positive end of the capacitor C1 and the second switching device S2.
  • the second end of S2 is connected to a capacitor C2, and the capacitor C2 is connected in parallel with the OVP module and the load of the step-down circuit.
  • the circuit shown in Figure 2 can realize the function of a step-down circuit; when S1 is used as the freewheeling switch, S3 is used as the main control switch. At this time, the circuit shown in Figure 2 can realize the function of a step-down circuit.
  • S1 as the main control switch
  • S3 is used as the freewheeling switch
  • the circuit shown in Figure 2 can realize the function of a step-down circuit.
  • S1, S2, and S2 may specifically be insulated gate bipolar transistors (IGBT), or the foregoing S1 to S2 are all metal-oxide semiconductor field effect transistors (metal-oxide-semiconductor field effect transistors). semiconductor field-effect transistor, MOSFET). It should be understood that the switching device in the embodiment of the present application may also be other possible switching devices, which is not limited in the embodiment of the present application.
  • IGBT insulated gate bipolar transistors
  • MOSFET semiconductor field-effect transistor
  • the OVP module is used to detect the output voltage Vo.
  • Vo is greater than the protection reference voltage
  • the OVP module controls S1, S2, and S3 to turn off to prevent output overvoltage.
  • the main control switch S1 and the backup switch S2 are not directly connected in series in the same loop, which reduces the possibility of simultaneous failure of the main control switch and the backup switch due to overcurrent, and ensures the safety of the circuit.
  • the circuit may also include an overcurrent protection (overcurrent protect, OCP) module.
  • OCP overcurrent protect
  • the OCP module is used to detect the input side current. When the output side current is greater than the protection reference current, the OCP module Control S1, S2, S3 to turn off to prevent the short-circuit failure of the switch bridge arm and the chain reaction after the failure.
  • the OCP module on the input side can detect overcurrent faster and quickly make protective measures to shut off S1 to S3.
  • the input side current is small and may not exceed the protection reference current, and the overvoltage protection cannot be effectively performed.
  • the OVP module on the output side can detect whether Vo is greater than the protection reference voltage, so as to realize overvoltage protection.
  • the short-term overshoot value of the output voltage can be effectively controlled, and the bridge arm can be effectively protected to ensure the safety of the circuit.
  • the first freewheeling device when the circuit implements the function of a step-down circuit, may be a diode. As shown in (a) of FIG. 3, the first freewheeling device of the buck circuit may be the first diode D1.
  • step-down circuit shown in FIG. 3 other devices have the same functions as the corresponding devices in the step-down circuit shown in FIG. 2, and will not be described in detail here. It should be understood that in the step-down circuit shown in Figure 3(a), due to the cut-off of the diode, the probability of the bridge arm S1-D1 being short-circuited is relatively small. Therefore, when the diode is used as the first freewheeling circuit of the step-down circuit When the device is used, the OCP module may not be required.
  • a step-down circuit that uses a diode as the first freewheeling device and does not require an OCP module is shown in Figure 3 (b).
  • a fault confirmation module can be added to the circuit to determine whether the main control switch S1 has a short-circuit fault.
  • the following is an example of adding a fault confirmation module to the step-down circuit shown in Figure 2 to introduce a step-down circuit that can perform fault confirmation.
  • a fault confirmation module is added to the step-down circuit shown in Figure 2.
  • the first end of the fault confirmation module is connected to the second end of the inductor L1 to measure the voltage Va; the first end of the fault confirmation module is connected to the first end of the input power source to measure the voltage Vin.
  • the voltage Va is close to the input voltage Vin, it is considered that a short circuit occurs in the main control switch S1 and the circuit cannot resume operation.
  • a certain threshold for example, the first threshold
  • the standby switch S2 is turned on, the main control switch S1 is turned off or on according to a certain frequency and duty cycle, the freewheeling switch S3 is turned on when the main control switch S1 is turned off, and the main control switch S1 is turned on Turn off when on.
  • FIG. 4 only shows a schematic diagram of a step-down circuit in which a fault confirmation module is added to the step-down circuit shown in FIG.
  • the connection mode and function of the confirmation module and the fault confirmation module are the same as the above scheme, so I will not repeat them here.
  • the second freewheeling device capacitor C1 can provide a freewheeling path for the inductor L1.
  • the second freewheeling device may also be a diode.
  • the second freewheeling device is a second diode D2. The first end of the diode D2 is connected to the second end of the inductor L1, and the second end of the diode D2 is connected to the input power supply. The first end is connected.
  • the step-down circuit of the embodiment of the present application may further include a third freewheeling device.
  • the second freewheeling device when the second freewheeling device is the second capacitor C2, the third freewheeling device is the second diode D2, and the connection of the diode D2 is as shown in FIG. 5 As shown in (a), the step-down circuit including the third freewheeling device is shown in (b) of FIG. 5.
  • the third freewheeling device may be the second capacitor C2.
  • the connection mode of the capacitor C2 is shown in Fig. 2 to Fig. 4, and the step-down circuit including the third freewheeling device is shown in Fig. 5(b).
  • FIG. 5 only shows a schematic diagram of the step-down circuit in which the second freewheeling device is changed or the third free-wheeling device is added on the step-down circuit shown in FIG. 2.
  • the step-down circuit shown in FIGS. 3 and 4 It is also possible to change the second freewheeling device or add a third freewheeling device in the manner shown in FIG. 5.
  • the connection mode and function of the second freewheeling device and the third freewheeling device are the same as the above-mentioned solution, and will not be repeated here. .
  • FIG. 6 is a schematic flowchart of a circuit control method according to an embodiment of the present application.
  • FIG. 7 is a circuit diagram for implementing the circuit control method of the embodiment of the present application. The circuit control method of the embodiment of the present application will be described in detail below in conjunction with FIG. 6 and FIG. 7.
  • the circuit control method of the embodiment of the present application includes step S610 to step S620.
  • S610 Determine that the output voltage of the circuit is greater than the protection reference voltage, or determine that the input current of the circuit is greater than the protection reference current.
  • Fig. 7 is a circuit diagram of a circuit control method of an embodiment of the present application. It should be understood that FIG. 7 only shows one possible form of the circuit, and the circuit may also be any of the step-down circuits shown in FIGS. 2 to 5 above.
  • the OCP module may include R1 to R3 and operational amplifiers X1 and X2 as shown in FIG. 7; wherein, the OVP module may include R4 and R5 as shown in FIG. 7.
  • the output voltage Vo of the circuit can be measured.
  • Vo is the voltage of the first capacitor C1 and the load.
  • Vo is greater than the second threshold, it can be determined that the output voltage is greater than the protection reference voltage.
  • the output voltage Vo may also be sampled, and according to the sampled Vo_samp of the output voltage, it is determined whether the output voltage is greater than the protection reference voltage.
  • Vo_samp is greater than the third threshold, the output may be determined The voltage is greater than the protection reference voltage.
  • the output voltage can be sampled by voltage division. As shown in Figure 7, the resistors R4 and R5 are connected in series and connected in parallel with the load, and the voltage at the midpoint of R4 and R5 is measured, that is, the sampled Vo_samp of the output voltage. It should be understood that the sampling of the output voltage Vo may also be other forms of sampling, which is not limited in the embodiment of the present application.
  • the input current may be sampled, and the measurement of the input current may be converted into the measurement of voltage.
  • the input current is converted into a corresponding second voltage: Vocp through R1 to R3 and operational amplifiers X1 and X2.
  • Vocp is greater than the fourth threshold
  • other forms may also be used to detect and convert the input current, which is not limited in the embodiment of the present application.
  • the measurement can be made more accurate by sampling the input current or output voltage.
  • S620 Turn off the first switching device and the second switching device.
  • the first switching device and the second switching device are turned off.
  • the protection measures will take effect, and the first switching device and the second switching device will be turned off, ensuring the safety of the circuit.
  • the first switching device and the second switching device are located in different circuit loops, so the two switching devices will not fail simultaneously due to a single fault, which further ensures the safety of the circuit.
  • the above circuit control method may further include step S630.
  • S630 Determine whether the first switching device is short-circuited.
  • the second switching device When it is determined that the first switching device is short-circuited, the second switching device is turned off. When it is determined that the first switching device is short-circuited, since the first switching device is the main control switch of the circuit, the main control switch is faulty, the circuit cannot resume normal operation, and the second switching device is kept off.
  • the first switching device When it is determined that the first switching device is not short-circuited, it is possible to wait for the output voltage to drop below the protection reference voltage, and then turn on the second switching device to restore the circuit to work. When the circuit resumes work, the first switching device is turned on or off according to the set duty cycle to realize the function of the step-down circuit.
  • the first switching device may be determined whether the first switching device is short-circuited according to the first voltage Va.
  • the first voltage Va is the voltage of the second terminal of the inductor L1.
  • the difference between Va and the input voltage Vin is greater than the first threshold, it can be determined that the first switching device is not short-circuited; when the difference between Va and Vin is less than or equal to the first threshold, it can be determined that the first switching device is short-circuited.
  • the first voltage can also be determined based on the sampling voltage of the first voltage Va.
  • R6 and R7 are connected in parallel with C2 after being connected in series, and the voltage at the midpoint of R6 and R7 is measured, that is, the sampling voltage Va_samp of Va.
  • Va and Va_samp have the following relationship:
  • the first voltage Va can be determined according to the sampled voltage Va_samp, and combined with the above method of determining whether the first switching device is short-circuited according to the magnitude of Va and Vin, it can be determined whether the first switching device is short-circuited.
  • sampling of the first voltage Va may also be other forms of sampling, which is not limited in the embodiment of the present application.
  • the detection of Vo, Vo_samp, Va, Va_samp, and Vocp can be performed by the controller, and the operations of turning on and off the first switching device and the second switching device can also be performed by the controller.
  • the controller may be a controller such as a digital signal processor (DSP), a single-chip microcomputer, and an advanced RISC machine (ARM).
  • DSP digital signal processor
  • ARM advanced RISC machine
  • Va or Va_samp By detecting Va or Va_samp, the cause of circuit failure can be further judged, especially when the circuit is started or the circuit stops working due to overvoltage, Va or Va_samp can be used to confirm whether the first switching device is short-circuited, which enhances the safety of the circuit .
  • the embodiment of the present application also includes a step-down device, and the step-down device includes the step-down circuit in the embodiment of the present application.
  • the step-down device may specifically be a step-down type direct current-direct current (DC-DC) conversion device.
  • the step-down device can be equipped in various electronic devices that require step-down conversion.
  • the step-down device can be equipped on a computer motherboard to reduce the 12V input voltage to 3.3V to supply power to the computer motherboard.
  • the step-down device can be equipped on the power conversion board of the communication system to reduce the input voltage exceeding 57V to the 48V voltage required by the communication system.
  • the disclosed device and method can be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the modules is only a logical function division, and there may be other divisions in actual implementation, for example, multiple modules or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented.
  • the functional modules in the various embodiments of the present application may be integrated into one processing unit, or each module may exist alone physically, or two or more modules may be integrated into one unit.

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Abstract

本申请提供了一种降压电路、降压装置和电路控制方法，该降压电路包括第一开关器件、第二开关器件、第一续流器件、第二续流器件、电感、第一电容和过压保护OVP模块，其中，第一开关器件和第一续流器件组成桥臂；电感的第一端与所述桥臂的中点相连，电感的第二端与第二开关器件相连；第二续流器件的第一端与电感的第二端相连；第一电容的第一端与第二开关器件相连，第一电容与OVP模块以及降压电路的负载并联；OVP模块用于检测所述降压电路的输出电压，降压电路的输出电压是所述负载的输入电压，当输出电压大于保护基准电压时，OVP模块控制第一开关器件和第二开关器件关断。该降压电路可以实现有效的过压保护，提高了电路的安全性。

Description

一种降压电路、降压装置和电路控制方法 技术领域
本申请涉及电路技术领域，尤其涉及一种降压电路、降压装置和电路控制方法。
背景技术
降压(buck)电路可以将较高的输入电压降低到符合后级负载要求的较低的电压进行输出，在各领域都有广泛的应用。buck降压电路中包括主控开关、二极管或同步整流开关、电感和电容，在工作时，主控开关以一定的频率及占空比开通，使得buck降压电路输出稳定的低压。
当主控开关短路时，输入电压通过短路的开关及电感串到输出端口，输出端口电压等于输入电压，比后级负载的设计值要高，对后级负载有可能造成损坏。例如消费类电子的CPU额定电压为1.8V，当3.3V电压直接接入该电子设备，CPU可能过压烧毁。再如，当72V电压直接接入到额定电压48V的设备时，可能触发输入过压、器件失效等。
因此需要过压保护措施保证电路的安全性。
发明内容
本申请提供一种降压电路、降压装置和电路控制方法，可以实现有效的过压保护。
第一方面，提供了一种降压电路，包括：第一开关器、第二开关器件、第一续流器件、第二续流器件、电感、第一电容和过压保护OVP模块，其特征在于：第一开关器件和第一续流器件组成桥臂；电感的第一端与桥臂的中点相连，电感的第二端与第二开关器件相连；第二续流器件的第一端与电感的第二端相连；第一电容的第一端与第二开关器件相连，第一电容与OVP模块以及降压电路的负载并联；OVP模块用于检测所述降压电路的输出电压，降压电路的输出电压是负载的输入电压，当输出电压大于保护基准电压时，OVP模块控制第一开关器件和第二开关器件关断。
上述技术方案中，当OVP模块检测到输出电压超过保护基准电压时，将会断开第一开关器件和第二开关器件，避免输出电压继续升高。并且，在上述降压电路中，第一开关器件和第二开关器件不是直接串联的，降低了第一开关器件和第二开关器件因为过流同时失效的可能性。
在一种可能的实现方式中，第一续流器件是第三开关器件，该电路还包括：过流保护OCP模块；该OCP模块与输入电源的第二端相连，OCP模块用于检测输入电流，当输入电流大于保护基准电流时，OCP模块控制第一开关器件、第二开关器件和第三开关器件关断。
当输入侧过流时，输出侧由于电容的存在电压的上升滞后于电流的上升，在输入侧增加OCP模块可以在检测到输入侧过流时快速做出保护措施，避免了由输入侧过流导致的过压以及输入侧过流产生的后续电路安全隐患。
在另一种可能的实现方式中，第一续流器件是第一二极管。
当第一续流器件是第一二极管时，由于第一二极管的截止作用，第一开关器件和第一二极管组成的桥臂短路的可能性较低，在这种情况下可以不需要OCP模块，简化了电路。
在另一种可能的实现方式中，该降压电路还包括故障确认模块，该故障确认模块的第一端与电感的第二端相连，故障确认模块的第二端与输入电源的第一端相连；该故障确认模块用于确定第一开关器件是否短路。
在另一种可能的实现方式中，当电感第二端的电压与输入电源第一端的电压之差大于第一阈值时，故障确认模块确定第一开关器件没有短路；当电感第二段的电压与输入电源第一端的电压之差小于等于第一阈值时，故障确认模块确定第一开关器件短路。
当OVP模块检测到输出电压大于保护基准电压而控制第一开关器件和第二开关器件断开，或者当OCP模块检测到输入电流大于保护基准电流而控制第一、第二、第三开关器件断开时，这两个模块均无法确认降压电路是否有短路发生，是否可以恢复工作。通过故障确认模块，可以确定降压电路的第一开关器件是否短路，从而确定降压电路是否可以恢复工作，进一步提高了降压电路的安全性。
在另一种可能的实现方式中，第二续流器件是第二电容，该第二电容的第二端接地；或者第二续流器件是第二二极管，该第二二极管的第二端与输入电源的第一端相连。
在另一种可能的实现方式中，该降压电路还包括第三续流器件；当第二续流器件是第二电容时，第三续流器件是第二二极管；或者，当第二续流器件是第二二极管时，第三续流器件是第二电容。
第二方面，提供了一种电路控制方法，该方法包括：确定电路的输出电压大于保护基准电压，或者确定电路的输入电流大于保护基准电流；关断第一开关器件和第二开关器件。其中，该电路包括：第一开关器件、第二开关器件、第一续流器件、第二续流器件、电感和第一电容；第一开关器件和第一续流器件组成桥臂；电感的第一端与桥臂的中点相连，电感的第二端与第二开关器件相连；第二续流器件的第一端与电感的第二端相连；第一电容的第一端与第二开关器件相连，第一电容与电路的负载并联；电路的输出电压是负载的输入电压，电路的输入电流是所述电路的输入电源所在回路的电流。
过压检测和过流检测相结合，当输出电压超过保护基准电压是电路将实现过压保护，断开第一和第二开关器件；当检测到输入侧电流升高，但是输出电压尚未超过保护基准电压时，仍然能断开第一和第二开关，实现有效的保护措施，避免输出侧电压过高。两种检测措施相结合，提高了电路的安全性。
在一种可能的实现方式中，该方法还包括：确定第一开关器件是否短路；当确定第一开关器件短路时，关断第二开关器件；当确定第一开关器件没有短路时，开通第二开关器件。
通过判断第一开关器件是否短路，可以进行电路故障的排查。当确定第一开关器件未短路时，可以使在输出侧电压下降到保护基准电压之下后开通第二开关器件，是电路恢复正常工作。
在另一种可能的实现方式中，确定所述第一开关器件是否短路包括：确定第一电压与输入电源的电压之差，第一电压是电感的第二端的电压；当第一电压与输入电源的电压之差大于第一阈值时，确定第一开关器件没有短路；当第一电压与输入电源的电压之差小于 或等于第一阈值时，确定第一开关器件短路。
在另一种可能的实现方式中，在确定第一电压与输入电源的电压之差之前，该方法还包括：确定第一电压的采样电压，根据第一电压的采样电压确定所述第一电压。
在另一种可能的实现方式中，确定电路的输出电压大于保护基准电压包括：确定输出电压大于第二阈值，确定电路的输出电压大于保护基准电压；或者，确定输出电压的采样电压大于第三阈值，确定电路的输出电压大于保护基准电压。
在另一种可能的实现方式中，确定电路的输入电流大于保护基准电流包括：确定输入电流对应的第二电压大于第四阈值，确定电路的输入电流大于保护基准电流。
在上述方案中，可以通过多种方式确定输出电压大于保护基准电压和确定输入电流大于保护基准电流，进一步提高了电路控制方法的灵活性。
第三方面，提供一种降压装置，该降压装置包括上述第一方面以及第一方面任一可能的实现方式的降压电路。
附图说明
图1是现有的一种降压电路过压保护方案的示意图；
图2是本申请实施例的一种降压电路示意图；
图3是本申请实施例的另一种降压电路示意图；
图4是本申请实施例的另一种降压电路示意图；
图5是本申请实施例的另一种降压电路示意图；
图6是本申请实施例的一种电路控制方法的流程示意图；
图7是本申请实施例的一种电路控制方法对应的电路示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。可以理解的是，所描述的实施例是本申请一部分的实施例，而不是全部的实施例。
在能源变换领域，常常需要将较高的输入电压转换为较低的输出电压。例如，在电脑主板的供电电路中，需要将12V的输入电压降低到3.3V，或者将3.3V的输入电压降低到1.8V；例如，通信系统二次电源中，需要将48V的母线电压降低到负载需要的电压值；例如，锂电电能转换板需要将大于57V的锂电电池转换为通信系统需要的48V电压等。
降压(buck)电路可以将较高的输入电压降低到符合后级负载要求的较低的电压进行输出，在上述能源变换场景有广泛的应用。在降压电路中，当降压电路的主控开关发生故障而短路失效时，输入的高电压将通过电感接到输出，使输出过压，损坏后级用电设备，危害电路安全。因此需要过压保护措施，在主控开关失效时保证降压电路的安全性。
图1是现有的降压电路保护方案的示意图。如图1所示，降压电路包括：开关器件101、开关器件102、开关器件103、电感104、电容105和过压保护(over voltage protect，OVP)模块106。其中开关器件101是主控开关，开关器件102是续流开关，开关器件101以合适的频率和占空比开通，使负载得到稳定的低于输入电压Vin的较低的电压Vo。为了避免主控开关失效时Vo过大，现有的方案中在负载处并联了OVP模块106，并且将开关器件103与开关器件101串联，开关器件103作为备用开关。当主控开关失效时，OVP 模块检测到输出电压Vo上升到过压保护点，作为备用开关的开关器件103关断以阻挡输入电压传递到输出。
但是，当主控开关101失效的原因是过流时，较大的电流也会流过备用开关103，因此主控开关器件101和备用开关器件103存在同时失效的可能。主控开关器件101和备用开关器件103同时失效后不能实现过压保护。并且，在续流开关器件102使用的是同步整流开关的情况下，当开关器件101短路且开关器件102导通时，开关器件101和开关器件102组成的桥臂回路将流过较大的短路电流，进一步诱发后续故障。例如，输入母线因过流被拉低，开关器件102进一步因过流短路失效，开关器件102失效后导致输入母线短路，是同一母线上的其他设备掉电。再如，开关器件102因过流开路失效，导致输输入电压直接串到输出，使输出过压。
本申请实施例提供的降压电路，可以实现有效的降压电路的过压保护，增强电路的安全性。
下面结合图2至图5详细介绍本申请实施例的降压电路。
图2是本申请一实施例的降压电路示意图。如图2所示，该降压电路包括：第一开关器件、第二开关器件、第一续流器件、第二续流器件、电感、第一电容、OVP模块。示例性地，在一些实施例中，如图2所示，第一开关器件是S1，第二开关器件是S2，电感是L1，第一电容是C1。
在一些实施例中，如图2所示，第一续流器件是第三开关器件S3，第二续流器件是第二电容C2。其中，S1和S3组成开关桥臂。电感L1的第一端连接到开关桥臂的中点，第二端连接电容C1的正端以及第二开关器件S2。S2的第二端端与电容C2相连，电容C2与OVP模块以及该降压电路的负载并联。
应理解，在一些实施例中，当S1作为主控开关，S3作为续流开关时，如图2所示的电路可以实现降压电路的功能；当S1作为续流开关，S3作为主控开关时，如图2所示的电路可以实现降压电路的功能。下面以S1作为主控开关为例，详细介绍本申请实施例的降压电路。
在一些实施例中，S1、S2和S2具体可以是绝缘栅双极型开关器件(insulated gate bipolar transistor，IGBT)，或者上述S1至S2均为金属-氧化物半导体场效应晶体管(metal-oxide-semiconductor field-effect transistor,MOSFET)。应理解，本申请实施例中的开关器件还可以是其他可能的开关器件，本申请实施例对此不作限定。
在如图2所示的降压电路中，OVP模块用于检测输出电压Vo。当Vo大于保护基准电压时，OVP模块控制S1、S2、S3关断，防止输出过压。
在上述方案中，主控开关S1和备用开关S2不直接串联在同一个回路，降低了因为过流导致的主控开关和备用开关同时失效的可能性，保证了电路的安全。
在一些实施例中，如图2所示，该电路还可以包括过流保护(over current protect，OCP)模块，OCP模块用于检测输入侧电流，当输出侧电流大于保护基准电流时，OCP模块控制S1、S2、S3关断，防止开关桥臂短路失效以及失效后的连锁反应。
并且，当主控开关短路时，输入电压Vin和输出电压Vo电压差较大，由于电容C1和C2的滤波作用，输出电压的上升会滞后于电流的上升，与输出侧的OVP模块检测到Vo过压相比，输入侧的OCP模块可以更快地检测到过流，迅速做出关断S1至S3的保护 措施。
在输入电压Vin和输出电压Vo的电压差较小，或者主控开关失效是呈现一定阻抗的情况下，输入侧电流较小，可能不会超过保护基准电流，不能有效地进行过压保护，此时输出侧的OVP模块可以检测Vo是否大于保护基准电压，从而实现过压保护。
通过OCP模块和OVP模块相结合，能有效控制输出电压短时上冲值，也能对桥臂直通的情况进行有效的保护，保证了电路的安全。
在一些实施例中，当电路实现降压电路的功能时，第一续流器件可以是一个二极管。如图3中的(a)所示，降压电路的第一续流器件可以是第一二极管D1。
图3所示的降压电路中，其他器件与图2所示的降压电路中的对应器件的功能相同，在此不再详述。应理解，在图3中的(a)所示的降压电路中，由于二极管的截止原因，桥臂S1-D1短路的概率较小，因此，当采用二极管作为降压电路的第一续流器件时，可以不需要OCP模块。采用二极管作为第一续流器件、且不需要OCP模块的降压电路如图3中的(b)所示。
在上述方案中，当OCP模块检测到输入侧过流，或者OVP模块检测到输出侧过压时，S1至S3均会关断，在这种情况下，无法知道主控开关S1是否有短路故障发生。当主控开关S1有短路故障时，电路不能恢复工作；当主控开关没有短路故障时，电路可以恢复工作。因此，在一些实施例中，可以在电路中增加故障确认模块，判断主控开关S1是否有短路故障发生。下面以在图2所示的降压电路中增加故障确认模块为例，介绍可以进行故障确认的降压电路。
如图4所示，在图2所示的降压电路中增加了故障确认模块。该故障确认模块的第一端与电感L1的第二端相连，测量电压Va；该故障确认模块的第一端与输入电源的第一端相连，测量电压Vin。当电压Va与输入电压Vin接近时，认为主控开关S1有短路发生，电路不能恢复工作。例如，在一些实施例中，当Va与Vin的电压差小于等于一定的阈值(例如，第一阈值)时，认为S1有短路电路，电路不能恢复工作。
在另一些实施例中，当电压Va低于输入电压Vin，且差距较大时，认为S1没有短路。例如，当Va与Vin的电压差大于一定的阈值(例如，第一阈值)时，认为S1没有短路，等待输出电压Vo下降到保护基准电压之下后，电路可以恢复工作。当恢复工作时，备用开关S2导通，主控开关S1按照一定的频率和占空比关断或者导通，续流开关S3在主控开关S1关断时导通，在主控开关S1导通时关断。
应理解，图4仅示出了在图2所示的降压电路上增加故障确认模块的降压电路示意图，在图3所示的降压电路中也可以按照图4所示的方式增加故障确认模块，故障确认模块的连接方式与功能与上述方案相同，在此不再赘述。
在上述图2至图4所示的降压电路中，第二续流器件电容C1可以为电感L1提供续流路径。在一些实施例中，该第二续流器件还可以是二极管。如图5中的(a)所示，第二续流器件是第二二极管D2，该二极管D2的第一端与电感L1的第二端相连，二极管D2的第二端与输入电源的第一端相连。
由于二极管D2和电容C2都可以为电感L1提供续流路径，因此，在一些实施例中，本申请实施例的降压电路还可以包括第三续流器件。
示例性地，如图2至图4所示，当第二续流器件是第二电容C2时，第三续流器件是 第二二极管D2，该二极管D2的连接方式如图5中的(a)所示，包括第三续流器件的降压电路如图5中的(b)所示。
示例性地，如图5中的(a)所示，当第二续流器件是第二二极管D2时，第三续流器件可以是第二电容C2。电容C2的连接方式如图2至图4所示，包括第三续流器件的降压电路如图5中的(b)所示。
应理解，图5仅示出了在图2所示的降压电路上改变第二续流器件或增加第三续流器件的降压电路示意图，在图3和图4所示的降压电路中也可以按照图5所示的方式改变第二续流器件或增加第三续流器件，第二续流器件和第三续流器件的连接方式与功能与上述方案相同，在此不再赘述。
本申请实施例还包括一种电路控制方法。图6是本申请一实施例的电路控制方法的流程示意图。图7是实现本申请实施例的电路控制方法的一种电路图。下面结合图6和图7详细介绍本申请实施例的电路控制方法。
如图6所示，本申请实施例的电路控制方法包括步骤S610至步骤S620。
S610，确定电路的输出电压大于保护基准电压，或者确定电路的输入电流大于保护基准电流。
图7是本申请实施例的电路控制方法的一种电路图。应理解，图7仅示出了电路的一种可能的形式，该电路还可以是上述图2至图5所示的任意一种降压电路。其中，OCP模块可以包括如图7所示的R1至R3以及运算放大器X1和X2；其中，OVP模块可以包括如图7所示的R4和R5。
示例性地，为了确定电路的输出电压大于保护基准电压，可以测量电路的输出电压Vo，Vo是第一电容C1和负载的电压，当Vo大于第二阈值时，可以确定输出电压大于保护基准电压。
示例性地，为了确定电路的输出电压大于保护基准电压，还可以对输出电压Vo进行采样，根据输出电压的采样Vo_samp确定输出电压是否大于保护基准电压，当Vo_samp大于第三阈值时，可以确定输出电压大于保护基准电压。
在一些实施例中，可以通过分压的方式对输出电压进行采样。如图7所示，电阻R4和R5串联后与负载并联，测量R4与R5中点的电压，即输出电压的采样Vo_samp。应理解，对输出电压Vo的采样还可以是其他形式的采样，本申请实施例对此不做限定。
示例性地，为了确定电路的输入电流大于保护基准电流，可以对输入电流进行采样，并且将对输入电流的测量转换为电压的测量。
在一些实施例中，如图7所示，通过R1至R3以及运算放大器X1和X2，将输入电流转换为对应的第二电压：Vocp。当确定Vocp大于第四阈值时，可以确定输入电流大于保护基准电流。应理解，还可以采用其他形式对输入电流进行检测与转换，本申请实施例对此不做限定。
在上述方案中，通过对输入电流或者输出电压的采样，可以使测量更加准确。
S620，关断第一开关器件和第二开关器件。
当确定电路的输出电压大于保护基准电压，或者输入电流大于保护基准电流时，关断第一开关器件和第二开关器件。
通过过流保护和过压保护相结合，输入电流和输出电压中任意一个超过保护基准值， 保护措施就生效，第一开关器件和第二开关器件将被关断，保证了电路的安全性。另外，本申请实施例中，第一开关器件和第二开关器件位于不同的电路回路中，因此两个开关器件不会因为单一的故障而同时失效，进一步保障了电路的安全。
在另一些实施例中，上述电路控制方法还可以包括步骤S630。
S630，确定第一开关器件是否短路。
当确定第一开关器件短路时，关断第二开关器件。当确定第一开关器件短路时，由于第一开关器件是电路的主控开关，因此主控开关有故障，电路不能恢复正常工作，保持第二开关器件关断。
当确定第一开关器件没有短路时，可以等待输出电压下降至保护基准电压之下后，开通第二开关器件，使电路恢复工作。当电路恢复工作时，第一开关器件按照设定的占空比开通或关断，实现降压电路的功能。
示例性地，可以根据第一电压Va确定第一开关器件是否短路。如图7所示，该第一电压Va是电感L1第二端的电压。当Va与输入电压Vin之差大于第一阈值时，可以确定第一开关器件没有短路；当Va与Vin之差小于等于第一阈值时，可以确定第一开关器件短路。
在另一些实施例中，还可以根据第一电压Va的采样电压确定第一电压。例如，如图7所示，R6和R7串联后与C2并联，测量R6与R7中点的电压，即Va的采样电压Va_samp。此时Va与Va_samp具有如下的关系：
Figure PCTCN2020095187-appb-000001
根据采样电压Va_samp即可确定第一电压Va，再结合上述根据Va与Vin的大小确定第一开关器件是否短路的方法，可以确定第一开关器件是否短路。
应理解，对第一电压Va的采样还可以是其他形式的采样，本申请实施例对此不做限定。
在上述方法中，对Vo、Vo_samp、Va、Va_samp以及Vocp的检测可以由控制器执行，并且对第一开关器件、第二开关器件开通与关断的操作也可以由控制器执行。示例性地，控制器可以是数字信号处理器(digital signal processor，DSP)、单片机、高级精简指令集处理器(advanced RISC machines，ARM)等控制器。
通过对Va或者Va_samp的检测，可以进一步判断电路故障的原因，特别是当电路启动或者电路由于过压而停止工作时，可以通过Va或者Va_samp确认第一开关器件是否短路，增强了电路的安全性。
本申请实施例还包括一种降压装置，该降压装置包括本申请实施例中的降压电路。该降压装置具体可以是一种降压型的直流-直流(direct current-direct current，DC-DC)变换装置。该降压装置可以装备在各种需要降压变换的电子设备中。例如，该降压装置可以装备在电脑主板上，将12V输入电压降到3.3V为电脑主板供电。再如，该降压装置可以装备在通信系统的电能转换板上，将超过57V的输入电压降至通信系统需要的48V电压。
应理解，说明书通篇中提到的“一些实施例”或“一实施例”意味着与实施例有关的特定特征、结构或特性包括在本申请的至少一个实施例中。因此，在整个说明书各处出现的“在一些实施例中”或“在一实施例中”未必一定指相同的实施例。此外，这些特定的 特征、结构或特性可以任意适合的方式结合在一个或多个实施例中。应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
本领域普通技术人员可以意识到，结合本文中所公开的实施例中描述的各方法步骤，能够以电子硬件、计算机软件或者二者的结合来实现，为了清楚地说明硬件和软件的可互换性，在上述说明中已经按照功能一般性地描述了各实施例的步骤。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。本领域普通技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
在本申请所提供的几个实施例中，可以理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个模块或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。
另外，在本申请各个实施例中的各功能模块可以集成在一个处理单元中，也可以是各个模块单独物理存在，也可以两个或两个以上模块集成在一个单元中。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (13)

  1. 一种降压电路，包括：第一开关器件、第二开关器件、第一续流器件、第二续流器件、电感、第一电容、和过压保护OVP模块，其特征在于：
    所述第一开关器件和所述第一续流器件组成桥臂；
    所述电感的第一端与所述桥臂的中点相连，所述电感的第二端与所述第二开关器件相连；
    所述第二续流器件的第一端与所述电感的第二端相连；
    所述第一电容的第一端与所述第二开关器件相连，所述第一电容与所述OVP模块以及所述降压电路的负载并联；
    所述OVP模块用于检测所述降压电路的输出电压，所述降压电路的输出电压是所述负载的输入电压，当所述输出电压大于保护基准电压时，所述OVP模块控制所述第一开关器件和所述第二开关器件关断。
  2. 根据权利要求1所述的降压电路，其特征在于，所述第一续流器件是第三开关器件，所述电路还包括：过流保护OCP模块；
    所述OCP模块与输入电源的第二端相连，所述OCP模块用于检测输入电流，当所述输入电流大于保护基准电流时，所述OCP模块控制所述第一开关器件、所述第二开关器件和所述第三开关器件关断。
  3. 根据权利要求1或2所述的降压电路，其特征在于，所述第一续流器件是第一二极管。
  4. 根据权利要求1-3中任一项所述的降压电路，其特征在于，所述电路还包括：故障确认模块，所述故障确认模块的第一端与所述电感的第二端相连，所述故障确认模块的第二端与所述输入电源的第一端相连；
    所述故障确认模块用于确定所述第一开关器件是否短路。
  5. 根据权利要求1-4中任一项所述的电路，其特征在于，
    所述第二续流器件是第二电容，所述第二电容的第二端接地；
    或者，所述第二续流器件是第二二极管，所述第二二极管的第二端与所述输入电源的第一端相连。
  6. 根据权利要求5所述的电路，其特征在于，所述电路还包括：第三续流器件，
    其中，当所述第二续流器件是所述第二电容时，所述第三续流器件是所述第二二极管；
    或者，当所述第二续流器件是所述第二二极管时，所述第三续流器件是所述第二电容。
  7. 一种电路控制方法，其特征在于，所述方法包括：
    确定电路的输出电压大于保护基准电压，或者确定电路的输入电流大于保护基准电流；
    关断第一开关器件和第二开关器件；
    其中，所述电路包括：所述第一开关器件、所述第二开关器件、第一续流器件、第二续流器件、电感和第一电容；
    所述第一开关器件和所述第一续流器件组成桥臂；
    所述电感的第一端与所述桥臂的中点相连，所述电感的第二端与所述第二开关器件相连；
    所述第二续流器件的第一端与所述电感的第二端相连；
    所述第一电容的第一端与所述第二开关器件相连，所述第一电容与所述电路的负载并联；
    所述电路的输出电压是所述负载的输入电压，所述电路的输入电流是所述电路的输入电源所在回路的电流。
  8. 根据权利要求7所述的方法，其特征在于，所述方法还包括：确定所述第一开关器件是否短路；
    当确定所述第一开关器件短路时，关断所述第二开关器件；
    当确定所述第一开关器件没有短路时，开通所述第二开关器件。
  9. 根据权利要求8所述的方法，其特征在于，所述确定所述第一开关器件是否短路包括：
    确定第一电压与输入电源的电压之差，所述第一电压是所述电感的第二端的电压；
    当所述第一电压与输入电源的电压之差大于第一阈值时，确定所述第一开关器件没有短路；
    当所述第一电压与输入电源的电压之差小于或等于第一阈值时，确定所述第一开关器件短路。
  10. 根据权利要求9所述的方法，其特征在于，在所述确定第一电压与输入电源的电压之差之前，所述方法还包括：
    确定第一电压的采样电压，根据所述第一电压的采样电压确定所述第一电压。
  11. 根据权利要求7-10中任一项所述的方法，其特征在于，所述确定电路的输出电压大于保护基准电压包括：
    确定所述输出电压大于第二阈值，确定电路的输出电压大于保护基准电压；
    或者，确定所述输出电压的采样电压大于第三阈值，确定电路的输出电压大于保护基准电压。
  12. 根据权利要求7-11中任一项所述的方法，其特征在于，所述确定电路的输入电流大于保护基准电流包括：
    确定所述输入电流对应的第二电压大于第四阈值，确定电路的输入电流大于保护基准电流。
  13. 一种降压装置，其特征在于，所述降压装置包括如权利要求1-6中任一项所述的降压电路。
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