WO2022041856A1 - 一种串并联变换器保护系统、控制器及变换器 - Google Patents

一种串并联变换器保护系统、控制器及变换器 Download PDF

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Publication number
WO2022041856A1
WO2022041856A1 PCT/CN2021/093999 CN2021093999W WO2022041856A1 WO 2022041856 A1 WO2022041856 A1 WO 2022041856A1 CN 2021093999 W CN2021093999 W CN 2021093999W WO 2022041856 A1 WO2022041856 A1 WO 2022041856A1
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WIPO (PCT)
Prior art keywords
converter
controller
switch tube
switch
threshold
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PCT/CN2021/093999
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English (en)
French (fr)
Inventor
曹震
陈东
姚晓锋
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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 JP2023513575A priority Critical patent/JP2023539260A/ja
Priority to EP21859701.1A priority patent/EP4195475A4/en
Priority to AU2021334490A priority patent/AU2021334490A1/en
Publication of WO2022041856A1 publication Critical patent/WO2022041856A1/zh
Priority to US18/174,855 priority patent/US20230223835A1/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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/102—Parallel operation of dc sources being switching converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/14—Balancing the load in a network
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • 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
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • 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
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/0077—Plural converter units whose outputs are connected in series
    • 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
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the embodiments of the present application relate to the technical field of circuits, and in particular, to a series-parallel converter protection system, a controller, and a converter.
  • Photovoltaic power optimizers generally use multiple converters in series to input to the inverter, while different optimizers are usually connected in parallel to increase the input power.
  • Embodiments of the present application provide a series-parallel converter protection system, a controller and a converter, which bypass the converter when the voltage is too large to prevent voltage and current from impacting the internal components of the converter.
  • an embodiment of the present application provides a protection system for a series-parallel converter, including a controller, a driver, a first switch tube and a second switch tube; an input end of the converter is connected to the converter through the first switch tube the output end of the converter, the controller is connected to the first switch tube through the driver to control the turn-on and turn-off of the first switch tube; the output end of the converter is connected to the second switch tube
  • the transistors are connected in parallel, and the controller is connected to the second switch tube through the driver to control the turn-on and turn-off of the second switch tube; when the output voltage of the converter is greater than the first threshold, the The controller controls the first switch to be turned off and the second switch to be turned on.
  • the controller when the output voltage of the converter is greater than the first threshold, bypasses the converter by controlling the first switch tube to be turned off and the second switch tube to be turned on, preventing the Voltage and current impact the internal components of the converter.
  • the input end of the converter is connected in parallel with a first capacitor
  • the output end of the converter is connected in parallel with a second capacitor
  • the second capacitor is connected to the An inductor is arranged on a connecting line between the second switching tubes.
  • the system further includes an auxiliary power supply; the auxiliary power supply is connected in parallel with the input end of the converter.
  • the first switch tube and the first diode are in anti-parallel, and the second switch tube and the second diode are anti-parallel.
  • the controller when the input voltage of the converter is less than the second threshold, controls the first switch tube and the second switch tube to turn off break.
  • the controller controls the first The two switches are turned off and the output voltage of the converter is re-detected; if the output voltage of the converter is greater than the first threshold, the controller controls the first switch to turn off and controls the second switch The tube is turned on; if the output voltage of the converter is not greater than the first threshold, the converter works normally. After the controller controls the second switch tube to be turned off, the converter is reconnected to the grid (exiting the bypass state), and if the output voltage of the converter returns to normal, the converter works normally. In some implementation manners, the controller may control the first switch to be turned on and the second switch to be turned off, and then perform re-detection.
  • the controller specifically controls the conduction of the second switch in a pulse width modulation PWM chopper manner.
  • an embodiment of the present application provides a controller, where the controller is configured to perform the following steps: detecting an output voltage of a converter; and controlling the first switch when the output voltage of the converter is greater than a first threshold The tube is turned off and the second switch tube is controlled to be turned on.
  • the controller is further configured to: when the input voltage of the converter is less than a second threshold, control the first switch and the first switch. The second switch is turned off.
  • the controller is further used for: re-detecting the output voltage of the converter.
  • the controller when the elapsed time after the output voltage of the converter is greater than the first threshold for the first time is greater than the preset time threshold, the controller is further configured to: Controlling the second switch tube to turn off and re-detecting the output voltage of the converter; if the output voltage of the converter is greater than the first threshold, the controller controls the first switch tube to turn off and controls all The second switch tube is turned on; if the output voltage of the converter is not greater than the first threshold, the converter operates normally.
  • an embodiment of the present application provides a converter, the converter includes a conversion circuit, an input end of the conversion circuit is connected to at least one photovoltaic cell panel, and an output end of the conversion circuit is connected to a power grid; A first switch tube is connected between the input end and the output end, and a second switch tube is connected between the output ends of the conversion circuit; the converter further includes the series-parallel converter protection system described in the first aspect, The series-parallel converter protection system is connected to the conversion circuit through the first switch tube and the second switch tube; or the converter further includes the controller according to the second aspect, the controller The first switch tube and the second switch tube are connected through a driver.
  • Figure 1 is a schematic diagram of a series-parallel converter connected to an inverter
  • FIG. 2 is a schematic diagram of the internal structure of the converter 1012
  • FIG. 3 is a schematic diagram of a series-parallel converter protection system provided by the application.
  • FIG. 4 is a schematic diagram of a current path of a protection process in an embodiment of the present application.
  • FIG. 5 is a flowchart of a protection strategy method of the controller 301 in an embodiment of the present application
  • FIG. 6 is a flowchart of steps of an overvoltage protection action in an embodiment of the present application.
  • FIG. 7 is a voltage timing diagram corresponding to the process shown in FIG. 6;
  • FIG. 8 is a timing diagram corresponding to the controller 301 turning on the switch transistor Q2 in a PWM chopper manner according to an embodiment of the present application.
  • Embodiments of the present application provide a series-parallel converter protection system, a controller and a converter, which bypass the converter when the voltage is too large to prevent voltage and current from impacting the internal components of the converter.
  • words such as “exemplary” or “for example” are used to represent examples, illustrations or illustrations. Any embodiments or designs described in the embodiments of the present application as “exemplary” or “such as” should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as “exemplary” or “such as” is intended to present the related concepts in a specific manner.
  • FIG. 1 is a schematic diagram of a series-parallel converter connected to an inverter.
  • the first optimizer 101 and the second optimizer 102 are connected in parallel with the inverter 103 .
  • the first optimizer 101 is composed of a plurality of converters 1012 connected in series. The input end of each converter 1012 can be connected to the photovoltaic cell panel 1011, and the output ends of the converters 1012 are connected in series as shown in FIG. 1 to form two output ends. as the output of the first optimizer 101 .
  • the internal structure of the second optimizer 102 may be similar to that of the first optimizer 101 , which is not shown in detail in FIG. 1 and will not be repeated here. In other cases, the second optimizer 102 may also be other internal structures, which are not limited in this embodiment of the present application.
  • the photovoltaic panel 1011 may be a device that converts solar energy into electrical energy, and the specific model, installation method, and size of the panel area are not limited in the embodiments of the present application.
  • the photovoltaic panels 1011 can be replaced with corresponding devices.
  • the photovoltaic panels 1011 may be replaced by wind turbines.
  • the photovoltaic panel 1011 may be replaced by an energy storage battery.
  • the photovoltaic cell panel 1011 can be replaced with a different device according to actual needs, and connected to the converter 1012, which is not repeated in this embodiment of the present application.
  • the converter 1012 may refer to a DC-DC converter. In practical applications, the converter 1012 may also be other types of converters, which are not limited in this embodiment of the present application.
  • FIG. 2 is a schematic diagram of the internal structure of the converter 1012 .
  • the internal structure of the converter 1012 may include a switch transistor Q1, a switch transistor Q2, a capacitor C1, a capacitor C2 and an inductor L.
  • a capacitor C1 is connected in parallel between the input end 201 and the input end 202 of the converter
  • a capacitor C2 is connected in parallel between the output end 203 and the output end 204 of the converter.
  • a switch transistor Q1 and an inductor L are connected in series between the input end 201 and the output end 203 .
  • the switch tube Q2 is connected in parallel between the output end 204 and the connection end of the switch tube Q1 and the inductor L.
  • the switch transistor Q1 and the switch transistor Q2 may be triode transistors or MOS transistors, and in practical applications, they may also be other types, such as insulated gate bipolar transistors (IGBTs). Not limited. In some embodiments, the switch transistor Q1 and the switch transistor Q2 may each have anti-parallel diodes.
  • the staff will disconnect the input end of the corresponding inverter 1012 .
  • the output voltage of the second optimizer 102 will impact the converter 1012, causing damage to the devices (such as capacitors, switch tubes, etc.) inside the converter.
  • the line 104 is the current path before the operator disconnects the input terminal of the corresponding inverter 1012
  • the line 105 is the current path after the operator disconnects the input terminal of the corresponding inverter 1012 .
  • FIG. 3 is a schematic diagram of a series-parallel converter protection system provided by the present application.
  • the series-parallel converter protection system includes: a controller 301, a driver 303, a switch Q1 and a switch Q2.
  • the connection relationship between the switch tube Q1, the switch tube Q2, the input capacitor, the output capacitor, and the inductance is similar to that of the converter corresponding to FIG. 2, and will not be repeated here.
  • the input end of the converter is connected to the output end of the converter through the switch tube Q1, and the controller 301 is connected to the switch tube Q1 through the driver 303 for controlling the on and off of the switch tube Q1.
  • the output end of the converter is connected in parallel with the switch tube Q2, and the controller 301 is connected to the switch tube Q2 through the driver 303 for controlling the on and off of the switch tube Q2.
  • the controller when the output voltage Vo of the converter is greater than the first threshold, the controller controls the switch transistor Q1 to be turned off and the switch transistor Q2 to be turned on. If the output voltage Vo of the converter is greater than the first threshold value, it means that the voltage of the output terminal of the converter is relatively large, which will damage the internal components of the converter. Therefore, the controller 301 can control the switch tube Q1 to turn off and control the switch tube Q2 to turn on. , so that the current path does not pass through the switch Q1, but is short-circuited through the switch Q2 and output to another output terminal, which actually bypasses the converter 2 to avoid damage to the converter and solve the problem that the output voltage of the converter is too large. technical problems that lead to damage to the converter.
  • FIG. 4 is a schematic diagram of a current path of a protection process in an embodiment of the present application. As shown in FIG. 4 , after the controller 301 controls the switch tube Q1 to be turned off and the switch tube Q2 to be turned on, the current path flows through the switch tube Q2 in the converter 1012 (as shown by the line 106 in FIG. 4 ), and the conversion The device 1012 is bypassed.
  • the controller 301 can detect the output voltage Vo of the converter through the voltage detection unit 304 .
  • the voltage detection unit 304 may be a circuit or element capable of detecting voltage, such as a voltage sensor, etc., which is not limited in this embodiment of the present application.
  • the controller 301 can control the switch transistor Q1 and the switch transistor Q2 through the driver 303 .
  • the driver 303 can be a driving circuit, which is used to receive the control signal of the controller 301 and convert it into a corresponding high and low level and output it to the switch Q1 and the switch Q2, so as to control the switch Q1 and the switch Q2. on and off.
  • the embodiments of the present application do not limit the circuit or structure of the driver 303 .
  • auxiliary power supply 302 power to controller 301 and driver 303 is provided by auxiliary power supply 302 .
  • the input end of the auxiliary power supply 302 is connected in parallel with the input end of the converter for obtaining electric energy.
  • the auxiliary power supply 302 is also connected to the controller 301 and the driver 303 for outputting the obtained power to the controller 301 and the driver 303 .
  • the controller 301 can turn off the switch Q1 and the switch Q2, so that the current of the second optimizer 102 freewheels to the converter through the anti-parallel diode of the switch Q1 , so that the input voltage Vin of the converter rises to maintain the power supply of the auxiliary power supply.
  • the embodiment of the present application uses the control logic of the controller 301 to control the switching transistor Q2 to bypass the converter when the output voltage of the converter is too high, so as to prevent the internal devices of the converter from being damaged by the high voltage.
  • the switch Q2 can be controlled to be turned off, so that the electric energy can continue to flow to the input end of the converter, maintain the normal operation of the controller 301 and the driver 303, and realize the continuous protection of the converter. .
  • the staff can reconnect the corresponding converter 1012, and the staff can input an instruction to make the controller 301 turn on the switch tube Q1 and turn off the switch tube Q2, so that the conversion The device 1012 resumes normal operation.
  • the controller 301 may also perform timing after detecting that the output voltage Vo of the converter is greater than the first threshold value for the first time, and when the timing reaches the preset time threshold, the controller 301 re-detects the conversion the output voltage Vo of the device.
  • the controller 301 can control the switch Q1 to be turned on and the switch Q2 to be turned off, so that the converter 1012 can resume normal operation. In this case, the controller 301 can automatically control the converter to resume normal operation after the worker connects the photovoltaic cell panel 1011 back to the converter, without the need for the worker to operate, which is more automated.
  • FIG. 5 is a flowchart of a protection strategy method of the controller 301 in this embodiment of the present application. The process includes:
  • the controller 301 may detect the output voltage Vo of the converter through the voltage detection unit 304, which is similar to the description of the foregoing embodiments, and will not be repeated here.
  • the overvoltage protection action may include the following control logic:
  • the control switch Q1 When the output voltage Vo of the converter is greater than the first threshold value, the control switch Q1 is turned off and the switch Q2 is controlled to be turned on;
  • the switch Q1 and the second switch Q2 are controlled to be turned off.
  • control logic may be directly executed in the controller, or a related program (overvoltage protection program) may be set to implement the above logic, which is not limited in this embodiment of the present application.
  • steps shown in FIG. 6 may be performed for the overvoltage protection action, and please refer to the following embodiments for details.
  • the overvoltage protection action can control the output voltage Vo of the converter within a reasonable range, and maintain the input voltage Vin of the converter to prevent the auxiliary power supply 302 from being short of power. Therefore, when the staff replaces or repairs the photovoltaic panel 1011 , the overvoltage protection action can prevent the internal components of the converter from being damaged due to excessive voltage.
  • step 503 If the timing time reaches the preset time threshold, exit the overvoltage protection program, and return to step 501 .
  • the controller 301 may use a timer to count time. When the time counted by the timer reaches the preset time threshold, the controller 301 can exit the overvoltage protection program (or can control the switch Q2 to be turned off so that the converter is no longer bypassed), and then re-detect the output voltage of the converter. In some embodiments, after the controller 301 exits the overvoltage protection program, the switch transistor Q1 and the switch transistor Q2 may be disconnected, and then return to step 401 (ie, re-detect the output voltage of the converter). It can be understood that, after a period of time has elapsed, the staff may have completed the maintenance or replacement of the photovoltaic cell panel 1011 and reconnect it to the converter. Therefore, the converter is re-detected at intervals, and the normal operation can be restored after the photovoltaic panel 1011 is reconnected to the converter.
  • the controller 301 can control the switch transistor Q1 and the switch transistor Q2 to return to the normal working state, so as to restore the normal operation of the converter.
  • the controller may control the switch Q1 to be turned on and the switch Q2 to be turned off, so that the converter can resume normal operation.
  • the above-mentioned steps of the overvoltage protection action may be directly performed by the controller 301 , or may be performed by the overvoltage protection unit 305 inside the controller 301 .
  • the overvoltage protection unit 305 is a logic module inside the controller 301 , and may include a microprocessor and a memory, where an instruction is stored in the memory, and the microprocessor reads the instruction to execute the steps of the overvoltage protection action.
  • FIG. 6 is a flowchart of the steps of the overvoltage protection action in this embodiment of the present application. The process includes:
  • the controller 301 can detect the input voltage Vin and the output voltage Vo of the converter respectively through the voltage detection unit 304 , which is similar to the description of the voltage detection unit 304 in the previous embodiment, and will not be repeated here.
  • step 603 turning on the switch Q2
  • step 605 switching off the switch Q2
  • the controller 301 controls the switch Q2 to be turned on through the driver 303, the current received by the converter flows through the switch Q2, and the converter is bypassed at this time, and the internal devices of the converter will not be damaged.
  • the controller when the controller turns on the switch Q2, it can turn off the switch Q1 at the same time, so as to prevent the current from rushing to the input end of the converter. If the switch tube Q1 has been turned off, only the switch tube Q2 can be turned on.
  • step 604. Detect whether the input voltage Vin of the converter is less than the second threshold Vth2, if yes, go to step 605, if not, go back to step 603.
  • the input voltage Vin of the converter is less than the second threshold Vth2, indicating that the input voltage will no longer be able to provide power to the auxiliary power supply 302. Therefore, the controller may perform step 605 to turn off the switch tube Q2 so that the current can flow. Via the input terminal of the converter, the input voltage Vin rises again.
  • the current can be transmitted to the input end of the converter through the anti-parallel diode of the switch Q1, so that the input voltage Vin rises again.
  • FIG. 7 is a voltage timing diagram corresponding to the process shown in FIG. 6 .
  • the controller 301 detects that the output voltage Vo of the converter exceeds the first threshold Vth1, and turns on the switch Q2 (and turns off the switch Q1). Therefore, the converter is bypassed, and the input and output voltage of the converter is reduced.
  • the controller 301 can turn off the switch Q2, so that the converter is no longer bypassed, the current can flow into the converter again, and the input and output of the converter Voltage can rise.
  • the controller 301 can turn on the switch Q2 to bypass the converter, and the input and output voltage of the converter will decrease.
  • the controller 301 turns on or off the switch Q2 according to the specific situation of the input and output voltage of the converter, so that the input and output voltage of the converter cyclically decreases and rises, and is always kept within an appropriate range, and will not affect the conversion.
  • the device inside the converter is damaged, and the technical problem that the converter is damaged when the output voltage of the converter is too large is solved.
  • the controller 301 may control the switching transistor Q2 to be turned on in a pulse width modulation (pulse width modulation, PWM) chopping manner, as shown in FIG. 8 .
  • PWM pulse width modulation
  • FIG. 8 is a timing diagram corresponding to the controller 301 turning on the switch transistor Q2 in a PWM chopper manner according to an embodiment of the present application.
  • the controller 301 turns on the switch tube Q2 in a PWM chopping manner.
  • the switch tube Q2 performs PWM according to a certain duty cycle, and the duty cycle can be set according to the actual situation. This embodiment of the present application does not limit this.
  • the controller 301 turns on the switch Q2 in a PWM chopping manner, and its function is to slow down the drop of the output voltage Vo and the input voltage Vin of the converter, so that the controller 301 does not need to switch the control state frequently, and improves the system stability.
  • the other aspects of this embodiment are similar to those of the foregoing embodiments, and are not repeated here.
  • the first threshold Vth1 , the second threshold Vth2 , the preset time threshold, etc. in the foregoing embodiments may be specifically set according to actual conditions, and the specific numerical values of the foregoing thresholds are not limited in this embodiment of the present application.
  • Embodiments of the present application further provide a converter, including a converter circuit, the converter circuit is similar to the circuit corresponding to FIG. 2 , the input end of which is connected to at least one photovoltaic panel, and the output end is connected to the power grid.
  • the converter may include a series-parallel converter protection system as shown in FIG. 3 .
  • the series-parallel converter protection system is connected to the conversion circuit through the switch tube Q1 and the switch tube Q2, which is similar to FIG. 3 and will not be repeated here.
  • the converter may include a controller, and the controller is similar to the controller 301 in the foregoing embodiment corresponding to FIG. 3 , and details are not described herein again.
  • the controller can connect the switch tube Q1 and the switch tube Q2 through the driver.
  • the converter further includes an auxiliary power source, which is similar to the auxiliary power source 302 in the aforementioned embodiment corresponding to FIG. 3 .
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
  • the above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.
  • the integrated unit if implemented in the form of a software functional unit and sold or used as an independent product, may be stored in a computer-readable storage medium.
  • the technical solutions of the present application can be embodied in the form of software products in essence, or the parts that contribute to the prior art, or all or part of the technical solutions, and the computer software products are stored in a storage medium , including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage medium includes: U disk, mobile hard disk, Read-Only Memory (ROM, Read-Only Memory), Random Access Memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes .

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Abstract

本申请实施例提供一种串并联变换器保护系统，包括控制器、驱动器、第一开关管和第二开关管；变换器的输入端通过第一开关管连接变换器的输出端；变换器的输出端与第二开关管并联，控制器控制第一开关管和第二开关管的导通和关断；当变换器的输出电压大于第一阈值时，控制器控制第一开关管关断以及控制第二开关管导通。本申请实施例中，当变换器的输出电压大于第一阈值时，控制器通过控制第一开关管关断以及控制第二开关管导通，使得变换器旁路，防止电压电流冲击变换器内部器件。本申请实施例还提供相应的控制器及变换器。

Description

一种串并联变换器保护系统、控制器及变换器
本申请要求于2020年8月31日提交的、中国申请号为202010899466.5、发明名称为“一种串并联变换器保护系统、控制器及变换器”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及电路技术领域，尤其涉及一种串并联变换器保护系统、控制器及变换器。
背景技术
光伏功率优化器一般采用多个变换器串联的方式输入到逆变器，而不同的优化器之间通常采用输出并联的方式连接，以增大输入功率。
光伏功率优化器内部的多个变换器分别接入不同的光伏电池板。当光伏电池板需要维护时，维护工人就会断开对应变换器的输入端。然而此时，与该优化器输出并联的其他优化器的输出电压会冲击该光伏电池板对应变换器，使得该变换器内部的器件损坏。
发明内容
本申请实施例提供了一种串并联变换器保护系统、控制器及变换器，在电压过大时将变换器旁路，防止电压电流冲击变换器内部器件。
第一方面，本申请实施例提供一种串并联变换器保护系统，包括控制器、驱动器、第一开关管和第二开关管；变换器的输入端通过所述第一开关管连接所述变换器的输出端，所述控制器通过所述驱动器连接所述第一开关管，用于控制所述第一开关管的导通和关断；所述变换器的输出端与所述第二开关管并联，所述控制器通过所述驱动器连接所述第二开关管，用于控制所述第二开关管的导通和关断；当所述变换器的输出电压大于第一阈值时，所述控制器控制所述第一开关管关断以及控制所述第二开关管导通。本申请实施例中，当所述变换器的输出电压大于第一阈值时，控制器通过控制所述第一开关管关断以及控制所述第二开关管导通，使得变换器旁路，防止电压电流冲击变换器内部器件。
结合第一方面，在本申请实施例的一种实现方式中，所述变换器的输入端并联有第一电容，所述变换器的输出端并联有第二电容，所述第二电容与所述第二开关管之间的一条连接线上设置有电感。
结合第一方面，在本申请实施例的一种实现方式中，该系统还包括辅助电源；所述辅助电源与所述变换器的输入端并联。
结合第一方面，在本申请实施例的一种实现方式中，所述第一开关管与第一二极管反并联，所述第二开关管与第二二极管反并联。
结合第一方面，在本申请实施例的一种实现方式中，当所述变换器的输入电压小于第二阈值时，所述控制器控制所述第一开关管以及所述第二开关管关断。
结合第一方面，在本申请实施例的一种实现方式中，所述变换器的输出电压第一次大 于第一阈值后经过的时间大于预设时间阈值时，所述控制器控制所述第二开关管关断并重新检测所述变换器的输出电压；若所述变换器的输出电压大于第一阈值，则所述控制器控制所述第一开关管关断以及控制所述第二开关管导通；若所述变换器的输出电压不大于第一阈值，则变换器正常工作。控制器控制所述第二开关管关断后，变换器重新接入电网(退出旁路状态)，若变换器的输出电压恢复正常，则变换器正常工作。在一些实现方式中，控制器可以控制所述第一开关管导通以及控制所述第二开关管关断，再进行重新检测。
结合第一方面，在本申请实施例的一种实现方式中，所述控制器具体以脉冲宽度调制PWM斩波的方式控制所述第二开关管导通。
第二方面，本申请实施例提供一种控制器，所述控制器用于执行以下步骤：检测变换器的输出电压；当所述变换器的输出电压大于第一阈值时，控制所述第一开关管关断以及控制所述第二开关管导通。
结合第二方面，在本申请实施例的一种实现方式中，所述控制器还用于：当所述变换器的输入电压小于第二阈值时，控制所述第一开关管以及所述第二开关管关断。
结合第二方面，在本申请实施例的一种实现方式中，所述当所述变换器的输入电压小于第二阈值时，控制所述第一开关管以及所述第二开关管关断之后，所述控制器还用于：重新检测所述变换器的输出电压。
结合第二方面，在本申请实施例的一种实现方式中，所述变换器的输出电压第一次大于第一阈值后经过的时间大于预设时间阈值时，所述控制器还用于：控制所述第二开关管关断并重新检测所述变换器的输出电压；若所述变换器的输出电压大于第一阈值，则所述控制器控制所述第一开关管关断以及控制所述第二开关管导通；若所述变换器的输出电压不大于第一阈值，则所述变换器正常运行。
第三方面，本申请实施例提供一种变换器，该变换器包括变换电路，所述变换电路的输入端连接至少一个光伏电池板，所述变换电路的输出端连接电网；所述变换电路的输入端和输出端之间连接有第一开关管，所述变换电路的输出端之间连接有第二开关管；所述变换器还包括如第一方面所述的串并联变换器保护系统，所述串并联变换器保护系统通过所述第一开关管和所述第二开关管接入所述变换电路；或所述变换器还包括如第二方面所述的控制器，所述控制器通过驱动器连接所述第一开关管和所述第二开关管。
附图说明
图1为串并联变换器连接逆变器的示意图；
图2为变换器1012的内部结构示意图；
图3为本申请提供的一种串并联变换器保护系统的示意图；
图4为本申请实施例中保护过程的电流路径示意图；
图5为本申请实施例中控制器301的保护策略方法流程图；
图6为本申请实施例中过压保护动作的步骤流程图；
图7为图6所示流程对应的电压时序图；
图8为本申请实施例中控制器301以PWM斩波方式开通开关管Q2对应的时序图。
具体实施方式
本申请实施例提供了一种串并联变换器保护系统、控制器及变换器，在电压过大时将变换器旁路，防止电压电流冲击变换器内部器件。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”、“第三”、“第四”等(如果存在)是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的本申请的实施例能够以除了在这里图示或描述的那些以外的顺序实施。此外，术语“包括”和“对应于”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
在本申请实施例中，“示例性的”或者“例如”等词用于表示作例子、例证或说明。本申请实施例中被描述为“示例性的”或者“例如”的任何实施例或设计方案不应被解释为比其它实施例或设计方案更优选或更具优势。确切而言，使用“示例性的”或者“例如”等词旨在以具体方式呈现相关概念。
图1为串并联变换器连接逆变器的示意图。第一优化器101和第二优化器102并联后连接逆变器103。第一优化器101由多个变换器1012串联构成，每个变换器1012的输入端可以连接光伏电池板1011，变换器1012的输出端如图1所示的方式串联后形成两个输出端，作为该第一优化器101的输出端。
第二优化器102的内部构成可以与第一优化器101类似，图1中不再详细画出，且此处不再赘述。在另一些情况中，第二优化器102还可以是其他的内部结构，本申请实施例对此不做限定。
在第一优化器101中，光伏电池板1011可以是将太阳能转换为电能的装置，本申请实施例对其具体的型号、安装方式、电池板面积大小等不做限定。在其他新能源发电系统或储能系统中，光伏电池板1011可以用相应的装置代替。例如，在风能发电系统中，光伏电池板1011可以用风力发电机代替。又例如，在储能系统中，光伏电池板1011可以用储能电池来代替。在实际应用中，该光伏电池板1011可以根据实际需要用不同的装置替换，并接入变换器1012，本申请实施例对此不再赘述。
在第一优化器101中，变换器1012可以是指直流转直流变换器。在实际应用中，变换器1012也可以是其他类型的变换器，本申请实施例对此不做限定。
图2为变换器1012的内部结构示意图。该变换器1012的内部结构可以包括开关管Q1、开关管Q2、电容C1、电容C2和电感L。其中，该变换器的输入端201和输入端202之间并联有电容C1，该变换器的输出端203和输出端204之间并联有电容C2。输入端201和输出端203之间串联开关管Q1和电感L。开关管Q2并联在输出端204与开关管Q1和电感L的连接端之间。
其中，开关管Q1和开关管Q2可以是三极管或者是MOS管，在实际应用中，还可以是其他类型，例如绝缘栅双极型晶体管(insulated gate bipolar transistor，IGBT)，本 申请实施例对此不做限定。在一些实施例中，开关管Q1和开关管Q2可以各自反并联二极管。
请参阅图1，当第一优化器101的第一个光伏电池板1011需要维修维护或更换时，工作人员会断开对应变换器1012的输入端。此时第二优化器102的输出电压会冲击该变换器1012，使得该变换器内部的器件(如电容、开关管等)损坏。图1中，线条104为工作人员断开对应变换器1012输入端之前的电流路径，线条105为工作人员断开对应变换器1012输入端之后的电流路径。可见，当工作人员断开对应变换器1012输入端之后，电流电压加到了输入电容上，导致该电容损坏。在一些情况下，该电流电压还可能对开关管Q2造成冲击，损坏开关管Q2。
针对上述的技术问题，本申请提供了一种串并联变换器保护系统，如图3所示。图3为本申请提供的一种串并联变换器保护系统的示意图。该串并联变换器保护系统包括：控制器301、驱动器303、开关管Q1和开关管Q2。开关管Q1、开关管Q2、输入电容、输出电容、电感等的连接关系与图2对应的变换器类似，此处不再赘述。并且，变换器的输入端通过开关管Q1连接变换器的输出端，控制器301通过驱动器303连接开关管Q1，用于控制开关管Q1的导通和关断。变换器的输出端与开关管Q2并联，控制器301通过驱动器303连接开关管Q2，用于控制开关管Q2的导通和关断。
在本申请实施例中，当变换器的输出电压Vo大于第一阈值时，控制器控制开关管Q1关断以及控制开关管Q2导通。变换器的输出电压Vo大于第一阈值说明该变换器的输出端的电压比较大，将会损坏变换器内部的部件，因此控制器301此时可以控制开关管Q1关断以及控制开关管Q2导通，使得电流路径不会通过开关管Q1，而是通过开关管Q2短接并输出至另一个输出端，实际上将该变换器2旁路，避免变换器损坏，解决了变换器输出电压过大时导致变换器损坏的技术问题。
图4为本申请实施例中保护过程的电流路径示意图。如图4所示，当控制器301控制开关管Q1关断以及控制开关管Q2导通之后，电流路径在变换器1012中从开关管Q2流过(如图4中线条106所示)，变换器1012旁路。
在实际应用中，控制器301可以通过电压检测单元304来检测变换器的输出电压Vo。具体地，电压检测单元304可以是能够检测电压的电路或元件，例如电压传感器等，本申请实施例对此不做限定。
在实际应用中，控制器301可以通过驱动器303来控制开关管Q1以及开关管Q2。具体地，驱动器303可以是一种驱动电路，用来实现接收控制器301的控制信号，并转化为对应的高低电平输出至开关管Q1以及开关管Q2，从而控制开关管Q1以及开关管Q2导通和关断。本申请实施例对驱动器303的电路或结构不做限定。
在一些情况中，控制器301和驱动器303的电能由辅助电源302提供。辅助电源302的输入端与变换器的输入端并联，用于获取电能。辅助电源302还连接控制器301和驱动器303，用于将获取到的电能输出至控制器301和驱动器303。
当控制器控制开关管Q1关断以及控制开关管Q2导通之后，变换器输入电压Vin和输出电压Vo会下降。当变换器的输入电压Vin下降到第二阈值时，辅助电源302可能获取不 到足够的电能。因此当变换器的输入电压Vin下降到第二阈值时，控制器301可以开关管Q1以及开关管Q2关断，使得第二优化器102的电流通过开关管Q1反并联的二极管续流至变换器的输入端，从而变换器的输入电压Vin上升，以维持辅助电源的电能供应。
本申请实施例通过上述控制器301的控制逻辑，使得在变换器输出电压过高时能够控制开关管Q2将该变换器旁路，防止过高的电压损坏变换器内部器件。另一方面，在变换器输入电压过低时能够控制开关管Q2断开，使得电能能够续流至变换器的输入端，维持了控制器301和驱动器303的正常运作，实现变换器的持续保护。
当工作人员维护或更换完光伏电池板1011后，工作人员可以重新接通对应的变换器1012，则工作人员可以输入指令使得控制器301控制开关管Q1导通以及开关管Q2关断，使得变换器1012恢复正常工作。在工作人员不输入指令的情况下，控制器301也可以在第一次检测到变换器的输出电压Vo大于第一阈值后进行计时，当计时达到预设时间阈值时，控制器301重新检测变换器的输出电压Vo。若变换器的输出电压Vo小于第一阈值，则控制器301可以控制开关管Q1导通以及开关管Q2关断，使得变换器1012恢复正常工作。这种情况下，控制器301能够自动地在工作人员将光伏电池板1011接回变换器后控制变换器恢复正常工作，无需工作人员操作，更加自动化。
基于上述控制逻辑，控制器301可以执行如图5所示的步骤。图5为本申请实施例中控制器301的保护策略方法流程图。该流程包括：
501、检测变换器的输出电压。
在本申请实施例中，控制器301可以通过电压检测单元304来检测变换器的输出电压Vo，与前述实施例的描述类似，此处不再赘述。
502、若变换器的输出电压大于第一阈值，则进入过压保护动作，并开始计时。
在本申请实施例中，过压保护动作可以包括以下控制逻辑：
当变换器的输出电压Vo大于第一阈值时，控制开关管Q1关断以及控制开关管Q2导通；
当变换器的输入电压Vin小于第二阈值时，控制开关管Q1以及第二开关管Q2关断。
在实际应用中，控制器中可以直接执行上述控制逻辑，也可以设定相关程序(过压保护程序)来实现上述逻辑，本申请实施例对此不做限定。
示例性的，过压保护动作可以执行如图6所示的步骤，具体请参阅后面实施例。
过压保护动作可以将变换器的输出电压Vo控制在合理范围内，并且保持变换器的输入电压Vin，防止辅助电源302缺电。因此，在工作人员更换或维修光伏电池板1011时，该过压保护动作可以防止电压过大导致变换器内部元器件损坏。
503、若计时时间达到预设时间阈值，则退出过压保护程序，返回执行步骤501。
在本申请实施例中，控制器301可以通过计时器来计时。当计时器所计时间到达预设时间阈值时，控制器301可以退出过压保护程序(或者可以控制开关管Q2关断使得变换器不再旁路)，然后重新检测变换器的输出电压。在一些实施例中，控制器301退出过压保护程序后，可以断开开关管Q1和开关管Q2，再返回执行步骤401(即重新检测变换器的输出电压)。可以理解的是，当过去一段时间后，工作人员可能已经完成了光伏电池板1011的维修或更换，将其重新接入变换器。因此变换器每隔一段时间重新进行检测，则可以在光 伏电池板1011重新接入变换器后实现恢复正常工作。
504、若变换器的输出电压不大于第一阈值，则变换器正常运行。
在本申请实施例中，若光伏电池板1011没有拆卸，工作人员没有断开变换器的输入接口，则变换器的输出电压Vo可以处于正常工作的状态，不会超出第一阈值，因此变换器是正常运行的。可以理解的是，控制器301可以控制开关管Q1和开关管Q2恢复至正常工作的状态，从而使得变换器恢复正常运行。在一些实施例中，控制器可以控制开关管Q1导通，控制开关管Q2关断，以使得变换器恢复正常运行。
上述的过压保护动作的步骤可以由控制器301直接执行，也可以由控制器301内部的过压保护单元305来执行。过压保护单元305是控制器301内部的逻辑模块，可以包括微处理器以及存储器，该存储器中存储有指令，该微处理器读取该指令以执行过压保护动作的步骤。该过压保护动作的步骤可以如图6所示，图6为本申请实施例中过压保护动作的步骤流程图。该流程包括：
601、检测变换器的输入电压Vin和输出电压Vo。
在本申请实施例中，控制器301可以通过电压检测单元304分别检测变换器的输入电压Vin和输出电压Vo，与前述实施例中关于电压检测单元304的描述类似，此处不再赘述。
602、检测变换器的输出电压Vo是否大于第一阈值Vth1，若是，则执行步骤603，若否，则执行步骤605。
在本申请实施例中，当控制器检测到变换器的输出电压Vo大于第一阈值Vth1时，执行步骤603(开通开关管Q2)，以使得变换器旁路。当控制器检测到变换器的输出电压Vo不大于第一阈值Vth1时，执行步骤605(断开开关管Q2)。
603、开通开关管Q2。
在本申请实施例中，当控制器301通过驱动器303控制开关管Q2开通时，变换器接收到的电流从开关管Q2流过，此时变换器旁路，变换器内部器件不会损坏。
在一些情况中，控制器开通开关管Q2的时候可以同时断开开关管Q1，以防止电流冲击到变换器的输入端。若开关管Q1已经断开，则可以仅开通开关管Q2。
604、检测变换器的输入电压Vin是否小于第二阈值Vth2，若是，则执行步骤605，若否，则返回步骤603。
在本申请实施例中，变换器的输入电压Vin小于第二阈值Vth2，说明输入电压即将无法继续给辅助电源302提供电能，因此控制器可以执行步骤605，断开开关管Q2，使得电流可以流经变换器的输入端，输入电压Vin重新上升。
605、断开开关管Q2。
在本申请实施例中，控制器301断开开关管Q2后，电流可以通过开关管Q1反并联的二极管传输至变换器的输入端，使得输入电压Vin重新上升。
图7为图6所示流程对应的电压时序图。在t1时间段的开始，控制器301检测到变换器的输出电压Vo超过第一阈值Vth1，则开通开关管Q2(并关断开关管Q1)。因此，变换器旁路，变换器的输入输出电压会降低。
经过了t1时间段后，变换器的输入电压Vin小于第二阈值Vth2，则控制器301可以 关断开关管Q2，使得变换器不再旁路，电流可以重新流入变换器，变换器的输入输出电压可以上升。
经过了t2时间段后，变换器的输出电压大于第一阈值Vth1，则控制器301可以开通开关管Q2，使得变换器旁路，变换器的输入输出电压会降低。
本申请实施例中，控制器301根据变换器输入输出电压的具体情况开通或关断开关管Q2，使得变换器的输入输出电压循环地下降上升，始终保持在合适的范围内，不会对变换器内部的器件造成损坏，解决了变换器输出电压过大时导致变换器损坏的技术问题。
在另一些实施例中，控制器301可以以脉冲宽度调制(pulse width modulation，PWM)斩波的方式控制开关管Q2导通，如图8所示。
图8为本申请实施例中控制器301以PWM斩波方式开通开关管Q2对应的时序图。
在图8对应的实施例中，控制器301以PWM斩波方式开通开关管Q2，如图8所示，开关管Q2根据一定的占空比进行PWM，该占空比可以根据实际情况设置，本申请实施例对此不做限定。
在图8对应的实施例中，控制器301以PWM斩波方式开通开关管Q2，其作用是减缓变换器输出电压Vo和输入电压Vin的下降，使得控制器301不需要频繁切换控制状态，提高系统的稳定性。该实施例的其他情况与前述实施例类似，此处不再赘述。
上述各个实施例中的第一阈值Vth1、第二阈值Vth2、预设时间阈值等均可以根据实际情况进行具体的设定，本申请实施例对上述阈值的具体数值不做限定。
本申请实施例还提供一种变换器，包括变换电路，该变换电路与前述图2对应的电路类似，其输入端连接至少一个光伏电池板，输出端接入电网。
该变换器可以包括如图3所示的串并联变换器保护系统。该串并联变换器保护系统通过开关管Q1和开关管Q2接入变换电路，与图3类似，此处不再赘述。
或者，该变换器可以包括控制器，该控制器与前述图3对应实施例中的控制器301类似，此处不再赘述。该控制器可以通过驱动器连接开关管Q1和开关管Q2。在一些实施例中，该变换器还包括辅助电源，与前述图3对应的实施例辅助电源302类似。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统，装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统，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，所述单元的划分，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，例如多个单元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。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各 个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(ROM，Read-Only Memory)、随机存取存储器(RAM，Random Access Memory)、磁碟或者光盘等各种可以存储程序代码的介质。

Claims (12)

  1. 一种串并联变换器保护系统，其特征在于，包括控制器、驱动器、第一开关管和第二开关管；
    变换器的输入端通过所述第一开关管连接所述变换器的输出端，所述控制器通过所述驱动器连接所述第一开关管，用于控制所述第一开关管的导通和关断；
    所述变换器的输出端与所述第二开关管并联，所述控制器通过所述驱动器连接所述第二开关管，用于控制所述第二开关管的导通和关断；
    当所述变换器的输出电压大于第一阈值时，所述控制器控制所述第一开关管关断以及控制所述第二开关管导通。
  2. 根据权利要求1所述的系统，其特征在于，所述变换器的输入端并联有第一电容，所述变换器的输出端并联有第二电容，所述第二电容与所述第二开关管之间的一条连接线上设置有电感。
  3. 根据权利要求1至2任意一项所述的系统，其特征在于，还包括辅助电源；
    所述辅助电源与所述变换器的输入端并联。
  4. 根据权利要求1至3任意一项所述的系统，其特征在于，所述第一开关管与第一二极管反并联，所述第二开关管与第二二极管反并联。
  5. 根据权利要求4所述的系统，其特征在于，当所述变换器的输入电压小于第二阈值时，所述控制器控制所述第一开关管以及所述第二开关管关断。
  6. 根据权利要求1至5任意一项所述的系统，其特征在于，所述变换器的输出电压第一次大于第一阈值后经过的时间大于预设时间阈值时，所述控制器控制所述第二开关管关断并重新检测所述变换器的输出电压；
    若所述变换器的输出电压大于第一阈值，则所述控制器控制所述第一开关管关断以及控制所述第二开关管导通；
    若所述变换器的输出电压不大于第一阈值，则所述变换器正常运行。
  7. 根据权利要求1至6任意一项所述的系统，其特征在于，所述控制器具体以脉冲宽度调制PWM斩波的方式控制所述第二开关管导通。
  8. 一种控制器，其特征在于，所述控制器用于执行以下步骤：
    检测变换器的输出电压；
    当所述变换器的输出电压大于第一阈值时，所述控制器控制所述第一开关管关断以及控制所述第二开关管导通。
  9. 根据权利要求8所述的控制器，其特征在于，所述控制器还用于：
    当所述变换器的输入电压小于第二阈值时，控制所述第一开关管以及所述第二开关管关断。
  10. 根据权利要求8或9所述的控制器，其特征在于，所述当所述变换器的输入电压小于第二阈值时，控制所述第一开关管以及所述第二开关管关断之后，所述控制器还用于：
    重新检测所述变换器的输出电压。
  11. 根据权利要求8至10任意一项所述的控制器，其特征在于，所述变换器的输出电 压第一次大于第一阈值后经过的时间大于预设时间阈值时，所述控制器还用于：
    控制所述第二开关管关断并重新检测所述变换器的输出电压；
    若所述变换器的输出电压大于第一阈值，则所述控制器控制所述第一开关管关断以及控制所述第二开关管导通；
    若所述变换器的输出电压不大于第一阈值，则所述变换器正常运行。
  12. 一种变换器，其特征在于，所述变换器包括变换电路，所述变换电路的输入端连接至少一个光伏电池板，所述变换电路的输出端连接电网；
    所述变换电路的输入端和输出端之间连接有第一开关管，所述变换电路的输出端之间连接有第二开关管；
    所述变换器还包括如权利要求1至7任意一项所述的串并联变换器保护系统，所述串并联变换器保护系统通过所述第一开关管和所述第二开关管接入所述变换电路；或
    所述变换器还包括如权利要求8至11任意一项所述的控制器，所述控制器通过驱动器连接所述第一开关管和所述第二开关管。
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