WO2022247820A1 - 一种谐振开关电容变换器及其控制方法 - Google Patents

一种谐振开关电容变换器及其控制方法 Download PDF

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Publication number
WO2022247820A1
WO2022247820A1 PCT/CN2022/094649 CN2022094649W WO2022247820A1 WO 2022247820 A1 WO2022247820 A1 WO 2022247820A1 CN 2022094649 W CN2022094649 W CN 2022094649W WO 2022247820 A1 WO2022247820 A1 WO 2022247820A1
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Prior art keywords
switch
resonant
unit
capacitor
diode
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PCT/CN2022/094649
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English (en)
French (fr)
Inventor
于心宇
刘云峰
辛凯
许富强
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华为数字能源技术有限公司
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Priority to EP22810545.8A priority Critical patent/EP4336720A1/en
Publication of WO2022247820A1 publication Critical patent/WO2022247820A1/zh
Priority to US18/517,117 priority patent/US20240088785A1/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
    • H02M1/0095—Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
    • 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
    • H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
    • H02M3/07—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider using capacitors charged and discharged alternately by semiconductor devices with control electrode, e.g. charge pumps
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/01—Resonant DC/DC converters
    • 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
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • 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
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • 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
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/493—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode the static converters being arranged for operation in parallel
    • 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
    • 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
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • 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
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/4837—Flying capacitor converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • 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 present application relates to the circuit field, and more specifically, to a resonant switched capacitor converter and a control method thereof.
  • the resonant switched capacitor converter uses the resonant unit (resonant inductor and resonant capacitor) to transfer energy, which not only reduces the volume of the converter, but also reduces the charge and discharge Capacitors all work in a resonant state, so there is no current peak problem, and can be applied to occasions with large output currents.
  • the conversion power can be increased, but due to the different circuit parameters, the current of each branch in the RSCC may be uneven, which will affect the stress and loss of the power switching devices in the RSCC.
  • the present application provides a resonant switched capacitor converter and a control method thereof, which can realize current sharing of each parallel branch in the RSCC, thereby making the stress and loss of switches of each branch uniform.
  • a resonant switched capacitor converter including: an input capacitor and an output capacitor, N parallel resonant switched capacitor branches, each of the N resonant switched capacitor branches includes a switch unit and a resonant unit, and a controller, the controller is used to control the conduction state of the switch in the switch unit, so that the resonant unit obtains power from the input capacitor during the charging phase, and makes the resonant unit output power to the output capacitor during the discharging phase.
  • the controller is also used to: determine the average value of the characteristic current of the N resonant units, and the N resonant units correspond to the N resonant switched capacitor branches one by one, and the characteristic current is the instantaneous current of the resonant unit in one resonant switching cycle RMS or peak value of current.
  • the duty cycle of the control signal of the charging switch in the first switching unit is reduced, wherein, when the charging switch is turned on, its corresponding resonant switched capacitor branch In charging phase.
  • the duty cycle of the control signal of the discharge switch in the first switch unit is reduced, wherein, when the discharge switch is turned on, its corresponding resonant switch capacitance The branch is in the discharge phase.
  • the first resonant unit is any one of N resonant units
  • the first switch unit is a switch unit in the resonant switched capacitor branch where the first resonant unit is located, and N is an integer greater than 1.
  • the controller can determine the effective value or peak value of the instantaneous current flowing through the N resonant units in a resonant switching period, and the effective value or peak value can also be called the characteristic current, and further calculate the average value of the N characteristic currents , the average value can be understood as the standard current that each resonant unit bears.
  • the controller can be used to reduce the duty cycle of the control signal of the charging switch, through this In this way, the time that the branch where the first resonant unit is in the charging phase will be reduced, and in the next resonant switching period, the characteristic current of the first resonant unit will be reduced, so that the switches in the first switching unit will bear Stress and losses will be reduced.
  • the controller can be used to reduce the duty cycle of the control signal of the discharge switch, through which In this way, the time that the branch where the first resonant unit is in the discharge phase will be reduced, and in the next resonant switching cycle, the characteristic current of the first resonant unit will increase, so that the switches in the first switching unit will bear The stresses and losses will tend to average out.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • the controller is specifically configured to: determine that the characteristic current of the first resonance unit is greater than an average value and the difference between the characteristic current of the first resonance unit and the average value is greater than a first threshold When , reduce the duty cycle of the control signal of the charging switch. Or, when it is determined that the characteristic current of the first resonant unit is smaller than the average value and the difference between the characteristic current of the first resonant unit and the average value is greater than the second threshold, decrease the duty cycle of the control signal of the discharge switch.
  • the controller is specifically configured to: detect the instantaneous currents of the N resonance units, determine the characteristic currents of the N resonance units according to the instantaneous currents of the N resonance units, and determine the characteristic currents of the N resonance units according to the N resonance units The characteristic current of the resonant unit is averaged.
  • the controller includes a sampling unit and a control unit, and the sampling unit is specifically configured to: collect the instantaneous current information of the N resonant units, and send the instantaneous current information of the N resonant units to the control unit. current information.
  • the control unit is specifically used to: receive the instantaneous current information of the N resonant units, determine the characteristic currents of the N resonant units according to the instantaneous current information of the N resonant units, and calculate the average value according to the characteristic currents of the N resonant units.
  • the resonant switched capacitor converter is a two-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the switch unit includes a first switch and a second Switches
  • the first switch is a charging switch
  • the second switch is a discharging switch
  • each of the N resonant switched capacitor branches further includes a first diode and a second diode.
  • the first end of the first switch is connected to the first end of the input capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the resonance unit
  • the second end of the second switch is connected to the input capacitor The second end connection.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is a midpoint clamped NPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the input capacitor includes The first capacitor and the second capacitor
  • the switch unit includes a first switch, a second switch, a third switch and a fourth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • the N resonant switched capacitor branches Each also includes a first diode, a second diode, a third diode, and a fourth diode.
  • the first terminal of the first switch is connected to the first terminal of the first capacitor
  • the second terminal of the first switch is connected to the first terminal of the second switch and the cathode of the third diode
  • the second terminal of the second switch is connected to the cathode of the third diode.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the fourth switch is connected to the first end of the fourth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the anode of the third diode, and the cathode of the fourth diode.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is an active neutral point clamped ANPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the input The capacitor includes a first capacitor and a second capacitor
  • the switch unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • each of the N resonant switched capacitor branches further includes a first diode and a second diode.
  • the first end of the first switch is connected to the first end of the first capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the fifth switch
  • the second end of the second switch is connected to the first end of the fifth switch.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the sixth switch and the second end of the fourth switch is connected to the second end of the sixth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the second terminal of the fifth switch, and the first terminal of the sixth switch.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • a method for controlling a resonant switched capacitor converter includes: an input capacitor and an output capacitor, N parallel resonant switched capacitor branches, each of the N resonant switched capacitor branches One includes a switch unit and a resonant unit, and a controller, the controller is used to control the conduction state of the switch in the switch unit, so that the resonant unit obtains power from the input capacitor during the charging phase, and makes the resonant unit output power to the output during the discharging phase capacitance.
  • the method includes: the controller determines the average value of the characteristic currents of the N resonant units, the N resonant units correspond to the N resonant switched capacitor branches one by one, and the characteristic current is the effective instantaneous current of the resonant unit in one resonant switching cycle value or peak value.
  • the controller determines that the characteristic current of the first resonant unit is greater than the average value, the duty cycle of the control signal of the charging switch in the first switching unit is reduced, wherein, when the charging switch is turned on, its corresponding resonant switch capacitor supports The road is in the charging phase.
  • the controller determines that the characteristic current of the first resonant unit is smaller than the average value, the duty cycle of the control signal of the discharge switch in the first switch unit is reduced, wherein, when the discharge switch is turned on, its corresponding resonant switch The capacitor branch is in the discharge phase.
  • the first resonant unit is any one of N resonant units
  • the first switch unit is a switch unit in the resonant switched capacitor branch where the first resonant unit is located
  • N is an integer greater than 1.
  • the controller can determine the effective value or peak value of the instantaneous current flowing through the N resonant units in a resonant switching period, and the effective value or peak value can also be called the characteristic current, and further calculate the average value of the N characteristic currents , the average value can be understood as the standard current that each resonant unit bears.
  • the controller can be used to reduce the duty cycle of the control signal of the charging switch, through this In this way, the time that the branch where the first resonant unit is in the charging phase will be reduced, and in the next resonant switching period, the characteristic current of the first resonant unit will be reduced, so that the switches in the first switching unit will bear Stress and losses will be reduced.
  • the controller can be used to reduce the duty cycle of the control signal of the discharge switch, through which In this way, the time that the branch where the first resonant unit is in the discharge phase will be reduced, and in the next resonant switching cycle, the characteristic current of the first resonant unit will increase, so that the switches in the first switching unit will bear The stresses and losses will tend to average out.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • reducing the duty cycle of the control signal of the charging switch in the first switching unit includes: When the controller determines that the characteristic current of the first resonance unit is greater than the average value and the difference between the current of the first resonance unit and the average value is greater than a first threshold, the controller reduces the duty cycle of the control signal of the charging switch.
  • reducing the duty cycle of the control signal of the discharge switch in the first switch unit includes: the controller determines that the characteristic current of the first resonance unit is less than the average value And when the difference between the current of the first resonant unit and the average value is greater than the second threshold, the duty cycle of the control signal of the discharge switch is reduced.
  • the controller determines the average value of the characteristic currents of the N resonant units, including: the controller detects the instantaneous currents of the N resonant units, and determines according to the instantaneous currents of the N resonant units The characteristic currents of the N resonant units, and the average value is calculated according to the characteristic currents of the N resonant units.
  • the controller includes a sampling unit and a control unit, and the controller determines the average value of the characteristic currents of the N resonant units, including: the sampling unit collects the instantaneous current information of the N resonant units , and send the instantaneous current information of the N resonance units to the control unit, the control unit receives the instantaneous current information of the N resonance units, and determines the effective current of each of the N resonance units according to the instantaneous current information of the N resonance units value and mean.
  • the resonant switched capacitor converter is a two-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the switch unit includes a first switch and a second Switches
  • the first switch is a charging switch
  • the second switch is a discharging switch
  • each of the N resonant switched capacitor branches further includes a first diode and a second diode.
  • the first end of the first switch is connected to the first end of the input capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the resonance unit
  • the second end of the second switch is connected to the input capacitor The second end connection.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is a midpoint clamped NPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the input capacitor includes The first capacitor and the second capacitor
  • the switch unit includes a first switch, a second switch, a third switch and a fourth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • the N resonant switched capacitor branches Each also includes a first diode, a second diode, a third diode, and a fourth diode.
  • the first terminal of the first switch is connected to the first terminal of the first capacitor
  • the second terminal of the first switch is connected to the first terminal of the second switch and the cathode of the third diode
  • the second terminal of the second switch is connected to the cathode of the third diode.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the fourth switch is connected to the first end of the fourth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the anode of the third diode, and the cathode of the fourth diode.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is an active neutral point clamped ANPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series, and the input
  • the capacitor includes a first capacitor and a second capacitor
  • the switch unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • each of the N resonant switched capacitor branches further includes a first diode and a second diode.
  • the first end of the first switch is connected to the first end of the first capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the fifth switch
  • the second end of the second switch is connected to the first end of the fifth switch.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the sixth switch and the second end of the fourth switch is connected to the second end of the sixth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the second terminal of the fifth switch, and the first terminal of the sixth switch.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • a third aspect provides a maximum power point tracking MPPT combiner box, including the first aspect and the resonant switching capacitor RSCC in any one of the implementation manners of the first aspect.
  • a power supply system including the resonant switching capacitor RSCC in any one of the implementation manners of the foregoing first aspect and the first aspect.
  • Fig. 1 is a schematic block diagram of an application scenario of the present application.
  • Fig. 2 is a schematic diagram of a resonant switched capacitor converter RSCC provided by the present application.
  • Fig. 3 is a schematic structural diagram of a two-level RSCC provided by an embodiment of the present application.
  • Fig. 4 is a control sequence of the switches in the switching unit of the main power circuit in the two-level RSCC.
  • Fig. 5 is a schematic diagram of the change of the instantaneous current of the resonant unit in a resonant switching period in the two-level RSCC.
  • Fig. 6 is a schematic structural diagram of an NPC type three-level RSCC provided by an embodiment of the present application.
  • Fig. 7 is a control sequence of the switches in the switching unit of the main power circuit in the NPC type three-level RSCC.
  • Fig. 8 is a schematic diagram of the change of the instantaneous current of the resonant unit in a resonant switching period in the NPC type three-level RSCC.
  • Fig. 9 is a schematic structural diagram of an ANPC type three-level RSCC provided by an embodiment of the present application.
  • Fig. 10 is the control sequence of the switches in the switching unit of the main power circuit in the ANPC type three-level RSCC.
  • Fig. 11 is a schematic diagram of the instantaneous current change of the resonant unit in a resonant switching period in the ANPC type three-level RSCC.
  • FIG. 12 is a schematic diagram of a control method for a resonant switched capacitor converter provided in the present application.
  • Fig. 13 is a schematic structural diagram of a control device according to an embodiment of the present application.
  • Fig. 1 is a schematic block diagram of an application scenario of the present application.
  • the resonant switched capacitor converter (RSCC) of the present application can be used in a power supply system 100, and the power supply system 100 can generate electric energy and supply power to the grid.
  • the power supply system 100 may include a power supply module 110 , a maximum power point tracking (MPPT) combiner box 120 , and an inverter circuit 130 .
  • the MPPT combiner box 120 may include a DC-DC boost circuit 121 , a DC-DC boost circuit 122 and an RSCC 123 .
  • the positive output terminal of the DC-DC boost circuit 121 is connected to the positive input terminal of the inverter circuit 130 , and the negative output terminal of the DC-DC boost circuit 121 is connected to the zero point of the input terminal of the inverter circuit 130 .
  • the positive output terminal of the DC-DC boost circuit 122 is connected to the positive input terminal of the RSCC 123, and the negative output terminal of the DC-DC boost circuit 122 is connected to the negative input terminal of the RSCC 123.
  • the positive output terminal of the RSCC 123 is connected to the zero point of the input terminal of the inverter circuit 130, and the negative output terminal of the RSCC 123 is connected to the negative input terminal of the inverter circuit 130.
  • the RSCC 123 can convert the positive voltage output by the DC-DC booster circuit 2 into a negative voltage, and then connect it to the inverter circuit 130 in series with the voltage output by the DC-DC booster circuit 1 .
  • the power supply module 110 can output the generated electric energy to the MPPT combiner box 120, and the MPPT combiner box 120 can output the DC power to the inverter circuit 130 after performing DC voltage conversion, and the inverter circuit 130 can convert the DC power into AC power and convert the AC power output to the grid.
  • the power supply module 110 that provides electric energy may include, but not limited to, a photovoltaic (photovoltaic, PV) string and/or a battery.
  • the photovoltaic strings/batteries 111 and the photovoltaic strings/batteries 112 in the power supply module 110 can be the same, that is, both are photovoltaic strings or batteries, or 111 and 112 can also be different, that is, one of 111 and 112 is a battery , and one is a photovoltaic string, which is not limited in this application.
  • the negative output terminal of the DC-DC boost circuit 121 can also be connected to the negative output terminal of the RSCC 123, that is, the negative output terminal of the DC-DC boost circuit 121 and the DC-DC boost circuit
  • the negative output terminal of 122 is equipotential.
  • each power supply module may be the same or different.
  • the power supply system 100 in FIG. 1 may further include a transformer, which is used to receive the AC power output by the inverter unit 130, convert the AC power into a voltage, and then input it into the power grid.
  • a transformer which is used to receive the AC power output by the inverter unit 130, convert the AC power into a voltage, and then input it into the power grid.
  • the RSCC provided by the embodiment of the present application will be described below with reference to FIG. 2 to FIG. 11 .
  • Fig. 2 is a schematic diagram of a resonant switched capacitor converter RSCC 200 provided by the present application.
  • the two ends of the input capacitor Cin are respectively connected to the two ends of the input end of the main power circuit 210, that is, the BUS+ end and the 0 end in FIG. 0 terminal and BUS- terminal in Figure 2.
  • the input capacitor Cin may be one capacitor, or may be formed by connecting two or more capacitors in series.
  • the second input terminal of 220 (corresponding to terminal 0 in the figure) is used as the negative input terminal of RSCC 123, and the first output terminal of main power circuit 220 (corresponding to terminal 0 in the figure) is used as the positive output terminal of RSCC 123, the main power circuit The second output terminal of 220 (corresponding to the BUS- terminal in the figure) is used as the negative output terminal of RSCC 123.
  • the RSCC provided by the embodiment of the present application can also be used in other scenarios.
  • the first input terminal of the main power circuit 220 (corresponding to the BUS+ terminal in the figure) can be used as the positive output terminal of the RSCC 123 and the first input terminal of the main power circuit 220.
  • the second output terminal (corresponding to the BUS- terminal in the figure) is used as the negative output terminal of RSCC 123.
  • which two ends of the BUS+ end, the 0 end and the BUS- end are used as the positive and negative output ends of the RSCC 123 may depend on the actual application environment, and the embodiments of the present application are not limited.
  • each switch unit x includes a charge switch x and a discharge switch x, wherein the conduction period of the charge switch x can determine the period for the resonant unit x to obtain electric energy from the input capacitor Cin, that is, when the charge switch x is turned on , the RSC branch x where the charging switch x is located is in the charging phase.
  • the turn-on duration of the discharge switch x can determine the duration during which the resonant unit x outputs electric energy to the output capacitor Cout, that is, when the discharge switch x is turned on, the RSC branch x where the discharge switch x is located is in the discharge stage.
  • the present application provides a resonant switched capacitor converter RSCC, which can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being overstressed. Circuit failures caused by high stress and losses.
  • the controller 220 can be used to determine the average value of the characteristic currents of N resonant units, and the N resonant units correspond to the N resonant switched capacitor branches one by one, and the characteristic current is any resonant unit The rms or peak value of the instantaneous current during one resonant switching cycle.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the charging switch in the first switching unit. When the charging switch is turned on, its corresponding RSC The branch is in the charging phase.
  • the controller 200 can be used to reduce the duty cycle of the control signal of the discharge switch in the first switch unit, and when the discharge switch is turned on, its corresponding The RSC branch is in the discharge phase.
  • the first resonant unit is any one of the N resonant units
  • the first switch unit is a switch unit in the resonant switched capacitor branch where the first resonant unit is located. It should be understood that in the present application, N is an integer greater than 1.
  • the controller 220 can determine the effective value or peak value of the instantaneous current flowing through the N resonant units in one resonant switching period, and the effective value or peak value can also be called the characteristic current, and further calculate the average value of the N characteristic currents
  • the average value can be understood as the standard current that each resonance unit bears.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the charging switch, through which In this way, the time for the branch where the first resonant unit is in the charging phase will be reduced, and in the next resonant switching period, the characteristic current of the first resonant unit will be reduced, so that the switches in the first switching unit will bear The stress and loss will be reduced.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the discharge switch, by In this way, the time for the branch where the first resonant unit is in the discharge phase will be reduced, and in the next resonant switching period, the characteristic current of the first resonant unit will increase, so that the switch in the first switching unit The stress and loss suffered will tend to be averaged.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • the duty cycle refers to the ratio of the high level time of the control signal of a certain switch to the entire pulse period in a pulse period. For example, for a pulse width modulation wave (PWM wave) with a high level for 1 second and a low level for 1 second, the duty cycle is 50%.
  • PWM wave pulse width modulation wave
  • the specific reduction amount of the duty cycle of the control signal of the charging switch or the discharging switch can be closed-loop adjusted according to the difference between the characteristic current of the resonance unit and the average value.
  • the difference between the characteristic current and the average value is large, the reduction of the duty cycle can be larger, and when the difference is small, the reduction of the duty cycle can be small.
  • the controller 220 may be specifically configured to: when it is determined that the characteristic current of the first resonance unit is greater than the average value and the difference between the characteristic current of the first resonance unit and the average value is greater than a first threshold, reduce the The duty cycle of the control signal for the small charge switch. Or, when it is determined that the characteristic current of the first resonant unit is smaller than the average value and the difference between the characteristic current of the first resonant unit and the average value is greater than the second threshold, decrease the duty cycle of the control signal of the discharge switch.
  • the controller 220 can adjust the duty cycle of the control signal of the charging switch or the discharging switch when the difference between the characteristic current of the first resonant unit and the average value is greater than a certain threshold, which can avoid the Unnecessary control is performed to avoid current fluctuations and improve the control efficiency of RSCC.
  • the controller 220 is specifically configured to: detect the instantaneous currents of the N resonance units, and determine the characteristic currents of the N resonance units according to the instantaneous currents of the N resonance units, and further determine the characteristic currents of the N resonance units according to the The characteristic currents are averaged.
  • the controller 220 can detect the instantaneous current of the resonant unit in real time, obtain the effective value or peak value of the instantaneous current of the resonant unit within one resonant switching cycle, and further calculate the average value based on the effective value or peak value of the N resonant units.
  • the present application can detect the instantaneous current of the resonant unit of each branch in real time, and use the detection result for further control of the main power circuit 210, so as to realize the closed-loop adjustment of the main power circuit and improve the control efficiency of RSCC.
  • the controller includes a sampling unit and a control unit, and the sampling unit may be specifically configured to: collect instantaneous current information of the N resonant units, and send the instantaneous current information of the N resonant units to the control unit.
  • the control unit can be used to: receive the instantaneous current information of the N resonant units, determine the characteristic currents of the N resonant units according to the instantaneous current information of the N resonant units, and calculate the average value according to the characteristic currents of the N resonant units.
  • the functions of the controller 220 can be realized by the sampling unit and the control unit respectively. Therefore, the embodiment of the present application can realize the current sharing purpose of each parallel branch in the RSCC on the basis of the existing product architecture, reducing the cost .
  • FIG. 3 is a schematic structural diagram of a two-level RSCC 300 provided in an embodiment of the present application.
  • RSCC 300 includes a main power circuit 310 and a controller 320, and the main power circuit 310 is a two-level circuit topology.
  • FIG. 3 only illustrates that the main power circuit 310 includes two RSC branches (namely, the branch 10-1 and the branch 10-2), but the RSCC shown in FIG. 3 may also include 3 or more than 3 the same or different branches.
  • the main power circuit 310 includes an input capacitor Cin, an output capacitor Cout, and branches 10-1 and 10-2.
  • the two ends of the input capacitor Cin are respectively connected to the two ends of the input end of the main power circuit 310, that is, the BUS+ end and the 0 end in FIG. 0 terminal and BUS- terminal in Figure 3.
  • Both the branch circuit 10-1 and the branch circuit 10-2 include a switch unit 11, a resonance unit 12, and diodes D1 (ie, the first diode), D2 (ie, the second diode).
  • the switching unit 11 includes two power switching devices S1 (i.e. the first switch) and S2 (i.e. the second switch), and the resonant unit 12 includes a resonant capacitor Cr and a resonant inductor Lr connected in series.
  • the first end of the switch S1 is connected to the first end of the input capacitor Cin
  • the second end of the switch S1 is connected to the first end of the switch S2 and the first end of the resonance unit 12
  • the second end of the switch S2 is connected to the second end of the input capacitor.
  • the second end of the resonance unit 12 is connected to the anode of D1 and the cathode of D2
  • the cathode of D1 is connected to the first end of the output capacitor Cout
  • the anode of D2 is connected to the second end of the output capacitor Cout.
  • FIG. 4 shows the control sequence of the switches in the switch unit 11 of the main power circuit 310 by the controller 320 .
  • S1, S2, S3, and S4 are all off in the initial state.
  • S1 is turned on, and S2 remains unchanged.
  • S1 is continuously turned on, and S2 is continuously turned off.
  • S1 is turned off.
  • S2 is turned on.
  • S1 is continuously turned off, and S2 is continuously turned on.
  • S2 is turned off at time t4 .
  • the main power circuit 310 returns to the initial stage.
  • t 1 -t 4 can be called a resonant switching cycle.
  • the controller 320 can control the conduction state of the switch unit 11 in the main power circuit 310, so that any resonant unit x can obtain electric energy from the input capacitor Cin during the charging phase, and output electric energy to the output capacitor Cin during the discharging phase.
  • Capacitor Cout Capacitor Cout.
  • FIG. 5 is a schematic diagram of the variation of the instantaneous current flowing through the resonant unit 12 in the branch 10-1 within a resonant switching period. It can be seen from FIG. 4 and FIG. 5 that, in the charging phase and the discharging phase of the branch circuit 10-1, the direction of the instantaneous current flowing through the resonant unit is opposite.
  • the length of time t 1 -t 2 during which the switch S1 is turned on determines the length of time for charging the resonant capacitor Cr
  • the length of time t 3 -t 4 during which the switch S2 is turned on determines the length of time for the discharge of the resonant capacitor Cr. Therefore, S1 can also be called a charging switch, when it is turned on, the branch 10-1 is in the charging stage, and S2 can also be called a discharging switch, when it is turned on, the branch 10-1 is in the discharging stage.
  • Figures 4 and 5 take branch 10-1 as an example for illustration.
  • branch 10-2 the control sequence of the switches in switch unit 11 and the instantaneous current change of resonance unit 12 are the same as those of branch 10-1. of.
  • the control contents of the switch units 11 of the branch 10-1 and the branch 10-2 are not necessarily the same. It is possible that at a certain moment, the branch 10-1 is in the charging stage, while the branch 10-2 in the discharge phase.
  • the controller 320 can collect the instantaneous current flowing through the two resonant units 12 in one resonant switching period, and determine the characteristic currents of the two resonant units according to the instantaneous current of the resonant unit 12, and the characteristic current can be the instantaneous current in one resonant switching period
  • the peak value of the current can also be an effective value.
  • the arithmetic mean value of the characteristic currents is further calculated according to the characteristic currents of the N resonant units.
  • the controller 320 may be used to reduce the duty cycle of the control signal of the switch S1 in the branch 10-1.
  • the turn-off time of S1 can be advanced to t 2 ', so that the time that branch 10-1 is in the charging phase will be reduced, and in the next resonant switching period, the resonance The characteristic current of the cell 12 will be reduced, and therefore the stress and losses experienced by the switches in the switching cell 11 will be reduced.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the switch S2. Specifically, as shown in Figure 4 and Figure 5, the turn-off time of S2 can be advanced to t 4 ', so that the time for the branch where the resonant unit 12 is in the discharge phase will be reduced, and in the next resonant switching cycle , the characteristic current of the resonant unit 12 will increase, and therefore, the stress and loss borne by the switches in the switching unit 11 will tend to be averaged. For other branches, the situation is similar and will not be repeated here.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • FIG. 6 is a schematic structural diagram of a neutral point clamped (neutral point clamped, NPC) type three-level RSCC 400 provided by an embodiment of the present application.
  • RSCC 400 includes a main power circuit 410 and a controller 420, and the main power circuit 410 is an NPC type three-level topology.
  • FIG. 6 only illustrates that the main power circuit 410 includes two RSC branches (ie, branch 20-1 and branch 20-2), but the RSCC shown in FIG. 6 may also include 3 or more than 3 same or different branches.
  • the main power circuit 410 includes input capacitors C1 (ie, the first capacitor) and C2 (ie, the second capacitor), an output capacitor Cout, and branches 20 - 1 and 20 - 2 .
  • the two ends of the input capacitors C1 and C2 connected in series are respectively connected to the two ends of the input end of the main power circuit 410, that is, the BUS+ end and the 0 end in FIG. Both ends, that is, the 0 end and the BUS- end in Figure 6.
  • Both the branch 20-1 and the branch 20-2 include a switch unit 21, a resonance unit 22, and diodes D1 (ie, the first diode), D2 (ie, the second diode), D3 (ie, the third diode ), D4 (ie the fourth diode).
  • the switching unit 21 includes four power switching devices S1 (ie, the first switch), S2 (ie, the second switch), S3 (ie, the third switch), and S4 (ie, the fourth switch), and the resonant unit 22 includes a resonant capacitor connected in series Cr and resonant inductance Lr.
  • the first end of the switch S1 is connected to the first end of the first capacitor C1
  • the second end of the switch S1 is connected to the first end of the switch S2, and the cathode of D3, and the switch S2
  • the second end of the switch S3 is connected to the first end of the resonant unit 22, the second end of the switch S3 is connected to the first end of the switch S4, and the anode of D4 is connected, and the second end of the switch S4 is connected to the second capacitor
  • the second terminal of C2 is connected, and the first terminal of the second capacitor C2 is connected with the second terminal of the first capacitor C1, the anode of D3, and the cathode of D4.
  • the second end of the resonance unit is connected to the anode of D1 and the cathode of D2, the cathode of D1 is connected to the first end of the output capacitor Cout, and the anode of D2 is connected to the second end of the output capacitor Cout.
  • FIG. 7 shows the control sequence of the switches in the switch unit 21 of the main power circuit 410 by the controller 420 .
  • S1 , S2 , and S4 are in the off state, and S3 is in the on state.
  • S2 is turned on.
  • S3 is turned off.
  • S1 is turned on.
  • S1 is turned off.
  • S3 is turned on.
  • S4 is turned on.
  • S4 is turned off.
  • the circuit returns to the initial state.
  • t 1 -t 8 can be called a resonant switching cycle.
  • the controller 420 can control the conduction state of the switching unit 21 in the main power circuit 410, so that any resonant unit x can obtain electric energy from the input capacitor Cin during the charging phase, and output electric energy to the output capacitor Cin during the discharging phase.
  • Capacitor Cout Capacitor Cout.
  • FIG. 8 is a schematic diagram of the variation of the instantaneous current flowing through the resonant unit 22 in the branch 20-1 within a resonant switching cycle. It can be seen from FIG. 7 and FIG. 8 that, in the charging phase and the discharging phase of the branch circuit 20 - 1 , the direction of the instantaneous current flowing through the resonant unit is opposite.
  • the length of time t 3 -t 4 during which switch S1 is turned on determines the length of time for charging the resonant capacitor
  • the length of time t 7 -t 8 during which switch S4 is turned on determines the length of time for discharging the resonant capacitor. Therefore, S1 can also be called a charging switch, and when it is turned on, the branch 21-1 is in the charging stage, and S4 can also be called a discharging switch, and when it is turned on, the branch 21-1 is in the discharging stage.
  • Fig. 7 and Fig. 8 take the branch 20-1 as an example for illustration.
  • the control sequence of the switch in the switch unit 21 and the instantaneous current change of the resonance unit 22 are the same as those of the branch 20-1. of.
  • the control contents of the switch units 21 of the branch 20-1 and the branch 20-2 are not necessarily the same. It is possible that at a certain moment, the branch 20-1 is in the charging stage, while the branch 20-2 in the discharge phase.
  • the controller 420 can collect the instantaneous current flowing through the two resonant units 22 in one resonant switching period, and determine the characteristic currents of the two resonant units according to the instantaneous current of the resonant unit 22, and the characteristic current can be the instantaneous current in one resonant switching period
  • the peak value of the current can also be an effective value.
  • the arithmetic mean value of the characteristic currents is further calculated according to the characteristic currents of the N resonant units.
  • the controller 420 may be used to reduce the duty ratio of the control signal of the switch S1 in the branch 20 - 1 .
  • the turn-off time of S1 can be advanced to t 4 ', so that the time that branch 20-1 is in the charging phase will be reduced, and in the next resonant switching cycle, the resonant The characteristic current of the cell 22 will be reduced, and therefore the stress and losses experienced by the switches in the switching cell 21 will be reduced.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the switch S4. Specifically, as shown in Fig. 7 and Fig. 8, the turn-off time of S4 can be advanced to t 8 ′, so that the time for the branch where the resonant unit 22 is in the discharge phase will be reduced, and in the next resonant switching cycle , the characteristic current of the resonant unit 22 will increase, and therefore, the stress and loss borne by the switches in the switching unit 21 will tend to be averaged. For other branches, the situation is similar and will not be repeated here.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • FIG. 9 is a schematic structural diagram of an active neutral point clamped (Active Neutral Point Clamped, ANPC) type three-level RSCC 500 provided by an embodiment of the present application.
  • the RSCC 500 includes a main power circuit 510 and a controller 520, and the main power circuit 510 is an NPC type three-level topology.
  • FIG. 9 only illustrates that the main power circuit 510 includes two RSC branches (ie, branch 30-1 and branch 30-2), but the RSCC shown in FIG. 9 may also include 3 or more than 3 same or different branches.
  • the main power circuit 510 includes input capacitors C1 (ie, the first capacitor) and C2 (ie, the second capacitor), an output capacitor Cout, and branches 30 - 1 and 30 - 2 .
  • the two ends of the input capacitors C1 and C2 connected in series are respectively connected to the two ends of the input end of the main power circuit 510, that is, the BUS+ end and the 0 end in FIG. Both ends, that is, the 0 end and the BUS- end in Figure 9.
  • Both the branch circuit 30-1 and the branch circuit 30-2 include a switch unit 31, a resonance unit 32, and diodes D1 (ie, the first diode), D2 (ie, the second diode).
  • the switching unit 31 includes two power switching devices S1 (ie, the first switch) and S2 (ie, the second switch), and the resonant unit 12 includes a resonant capacitor Cr and a resonant inductor Lr connected in series.
  • the first end of the switch S1 is connected to the first end of the first capacitor C1
  • the second end of the switch S1 is connected to the first end of the switch S2 and the first end of the switch S5.
  • the second end of the switch S2 is connected to the first end of the switch S3 and the first end of the resonance unit 32
  • the second end of the switch S3 is connected to the first end of the switch S4, and the second end of the switch S6, and the second end of the switch S4
  • the two terminals are connected to the second terminal of the second capacitor C2, and the first terminal of the second capacitor C2 is connected to the second terminal of the first capacitor C1, the second terminal of the switch S5, and the first terminal of the switch S6.
  • the second end of the resonance unit 32 is connected to the anode of D1 and the cathode of D2, the cathode of D1 is connected to the first end of the output capacitor Cout, and the anode of D2 is connected to the second end of the output capacitor Cout.
  • FIG. 10 shows the control sequence of the switches in the switch unit 31 of the main power circuit 510 by the controller 520 .
  • S1 , S2 , S4 , and S6 are in the off state, and S3 , S5 are in the on state.
  • S5 is turned off and S6 is turned on.
  • S2 is turned on and S3 is turned off.
  • S1 is turned on.
  • S5 is turned on and S6 is turned off.
  • S2 is turned off and S3 is turned on.
  • S4 is turned on.
  • S4 is turned on.
  • S4 is turned off, and the circuit returns to the initial state.
  • t 1 -t 8 can be called a resonant switching cycle.
  • the controller 520 can control the conduction state of the switch unit 31 in the main power circuit 510, so that any resonant unit x can obtain electric energy from the input capacitor Cin during the charging phase, and output electric energy to the output capacitor Cin during the discharging phase.
  • Capacitor Cout Capacitor Cout.
  • FIG. 11 is a schematic diagram of the variation of the instantaneous current flowing through the resonant unit 32 in the branch 30-1 within a resonant switching cycle. It can be seen from FIG. 11 that, in the charging phase and the discharging phase of the branch circuit 30 - 1 , the direction of the instantaneous current flowing through the resonant unit is opposite.
  • the length of time t 3 -t 4 during which switch S1 is turned on determines the length of time for charging the resonant capacitor, and the length of time t 7 -t 8 during which switch S4 is turned on determines the length of time for discharging the resonant capacitor. Therefore, S1 can also be called a charging switch. When it is turned on, the branch 30 - 1 is in the charging stage. S4 can also be called a discharging switch. When it is turned on, the branch 10 is in the discharging stage.
  • Fig. 10 and Fig. 11 take the branch 30-1 as an example for illustration.
  • the control sequence of the switch in the switch unit 31 and the instantaneous current change of the resonance unit 32 are the same as those of the branch 30-1. of.
  • the control content of the switch unit 31 of the branch 30-1 and the branch 30-2 is not necessarily the same at the same moment, and it may be that at a certain moment, the branch 30-1 is in the charging stage, while the branch 30-2 is in the charging stage. discharge phase.
  • the controller 520 can collect the instantaneous current flowing through the two resonant units 32 in one resonant switching period, and determine the characteristic currents of the two resonant units according to the instantaneous current of the resonant unit 32, and the characteristic current can be the instantaneous current in one resonant switching period
  • the peak value of the current can also be an effective value.
  • the arithmetic mean value of the characteristic currents is further calculated according to the characteristic currents of the N resonant units.
  • the controller 520 can be used to reduce the duty cycle of the control signal of the switch S1 in the branch 30 - 1 .
  • the turn-off time of S1 can be advanced to t 4 ', so that the time that branch 30-1 is in the charging phase will be reduced, and in the next resonant switching period, the resonant The characteristic current of cell 32 will be reduced, and therefore the stress and losses experienced by the switches in switching cell 31 will be reduced.
  • the controller 220 can be used to reduce the duty cycle of the control signal of the switch S4. Specifically, as shown in Fig. 10 and Fig. 11, the turn-off time of S4 can be advanced to t 8 ′, so that the time for the branch where the resonant unit 32 is in the discharge phase will be reduced, and in the next resonant switching period , the characteristic current of the resonant unit 32 will increase, and therefore, the stress and loss borne by the switches in the switch unit 31 will tend to be averaged. For other branches, the situation is similar and will not be repeated here.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • the N parallel branches in the RSCC may be completely the same or different, that is, RSC branches with different topological structures may be connected in parallel to the main power circuit.
  • the input capacitor of the main power circuit 210 in FIG. 2 can be composed of two capacitors C1 and C2, and the topology of the RSC branch 1 can be as shown in the branch 10-1 in FIG. 3 , the topology of RSC branch 2 can be shown as branch 20-1 in Figure 6, and the topology of RSC branch 3 can be shown as branch 30 in Figure 9, which is not limited in the embodiment of the present application .
  • the functions of the controller 220, the controller 320, the controller 420, and the controller 520 can be realized by the sampling unit and the control unit respectively, and the sampling unit can be used to collect the The instantaneous current information of the N resonant units, and send the instantaneous current information of the N resonant units to the control unit.
  • the control unit can be used to receive the instantaneous current information of the N resonant units, determine the characteristic currents of the N resonant units according to the instantaneous current information of the N resonant units, and further calculate the arithmetic mean value of the characteristic currents according to the characteristic currents of the N resonant units .
  • the characteristic current is the effective value or peak value of the instantaneous current flowing through the resonant unit within one resonant switching period, wherein the effective value can be calculated according to the peak value, and the specific calculation method is to multiply the peak value by the square root of 2.
  • the average value can be divided by the total number N after summing N effective values or peak values.
  • the present application also provides a method for controlling a resonant switched capacitor converter.
  • the resonant switched capacitor converter includes an input capacitor, an output capacitor, N parallel resonant switched capacitor branches, and a controller.
  • Each of the N resonant switched capacitor branches includes a switch unit and a resonant unit.
  • the controller can control the conduction state of the switches in the switch unit, so that the resonant unit obtains power from the input capacitor during the charging phase, and makes the resonant unit output power to the output capacitor during the discharging phase.
  • the method includes: the controller determines the average value of the characteristic currents of the N resonant units, the N resonant units correspond to the N resonant switched capacitor branches one by one, and the characteristic current is the effective instantaneous current of the resonant unit in one resonant switching cycle value or peak value.
  • the controller determines that the characteristic current of the first resonant unit is greater than the average value, the duty cycle of the control signal of the charging switch in the first switching unit is reduced, and when the charging switch is turned on, its corresponding branch is in the charging stage .
  • the controller determines that the characteristic current of the first resonant unit is smaller than the average value, the duty cycle of the control signal of the discharge switch in the first switch unit is reduced, and when the discharge switch is turned on, its corresponding branch is at discharge phase.
  • the first resonant unit is any one of N resonant units
  • the first switch unit is a switch unit in the resonant switched capacitor branch where the first resonant unit is located, and N is an integer greater than 1.
  • the resonant switched capacitor converter RSCC provided by the present application can realize the current sharing of each parallel branch in the RSCC, so that the stress and loss of the switches in each branch can be evened out, and the switches in some branches can be prevented from being subjected to excessive stress. and circuit failures caused by losses.
  • reducing the duty cycle of the control signal of the charging switch in the first switch unit includes: the controller determines that the characteristic current of the first resonant unit When the current is greater than the average value and the difference between the current of the first resonant unit and the average value is greater than the first threshold, the duty cycle of the control signal of the charging switch is reduced.
  • reducing the duty cycle of the control signal of the discharge switch in the first switch unit includes: the controller determines that the characteristic current of the first resonant unit When the current is smaller than the average value and the difference between the current of the first resonant unit and the average value is larger than the second threshold, the duty cycle of the control signal of the discharge switch is reduced.
  • the controller determines the average value of the characteristic currents of the N resonance units, including: the controller detects the instantaneous currents of the N resonance units, and determines the characteristic currents of the N resonance units according to the instantaneous currents of the N resonance units, and according to the N Calculate the average value of the characteristic current of each resonant unit.
  • the controller includes a sampling unit and a control unit, and the controller determines the average value of the characteristic currents of the N resonance units, including: the sampling unit collects the instantaneous current information of the N resonance units, and sends the N resonance units to the control unit
  • the control unit receives the instantaneous current information of the N resonant units, and determines the effective value and average value of each of the currents of the N resonant units according to the instantaneous current information of the N resonant units.
  • the resonant switched capacitor converter is a two-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the switching unit includes a first switch and a second switch
  • the first switch is a charging switch
  • the second The second switch is a discharge switch
  • each of the N resonant switched capacitor branches further includes a first diode and a second diode.
  • the first end of the first switch is connected to the first end of the input capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the resonance unit
  • the second end of the second switch is connected to the input capacitor The second end connection.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is a midpoint clamped NPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the input capacitor includes a first capacitor and a second capacitor
  • the switch unit It includes a first switch, a second switch, a third switch and a fourth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • each of the N resonant switched capacitor branches further includes a first diode, The second diode, the third diode, and the fourth diode.
  • the first terminal of the first switch is connected to the first terminal of the first capacitor
  • the second terminal of the first switch is connected to the first terminal of the second switch and the cathode of the third diode
  • the second terminal of the second switch is connected to the cathode of the third diode.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the fourth switch is connected to the first end of the fourth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the anode of the third diode, and the cathode of the fourth diode.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • the resonant switched capacitor converter is an active neutral point clamped ANPC type three-level resonant switched capacitor converter
  • the resonant unit includes a resonant capacitor and a resonant inductor connected in series
  • the input capacitor includes a first capacitor and a second capacitor
  • the switch unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch
  • the first switch is a charging switch
  • the fourth switch is a discharging switch
  • the N resonant switched capacitor branches Each also includes a first diode, a second diode.
  • the first end of the first switch is connected to the first end of the first capacitor
  • the second end of the first switch is connected to the first end of the second switch and the first end of the fifth switch
  • the second end of the second switch is connected to the first end of the fifth switch.
  • the first end of the third switch is connected to the first end of the resonance unit
  • the second end of the third switch is connected to the first end of the fourth switch
  • the second end of the sixth switch and the second end of the fourth switch is connected to the second end of the sixth switch.
  • the second terminals of the two capacitors are connected, and the first terminal of the second capacitor is connected with the second terminal of the first capacitor, the second terminal of the fifth switch, and the first terminal of the sixth switch.
  • the second end of the resonance unit is connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is connected to the first end of the output capacitor, and the anode of the second diode is connected to the output capacitor The second end connection.
  • FIG. 12 is a schematic diagram of a control method for a resonant switched capacitor converter provided in the present application.
  • the control method for RSCC of the present application will be described below with reference to FIG. 12 .
  • S620 Determine the characteristic currents of the N resonance units according to the instantaneous currents of the N resonance units.
  • FIG. 13 is a schematic structural diagram of a control device 700 according to an embodiment of the present application.
  • the control device 700 includes a processor 710 and a communication interface 720 .
  • the control device 700 may also include a memory 730 .
  • the memory 730 may be included in the processor 710 .
  • the processor 710, the communication interface 720 and the memory 730 communicate with each other through an internal connection path, the memory 730 is used to store instructions, and the processor 710 is used to execute the instructions stored in the memory 730 to implement the control method provided by the embodiment of the present application.
  • the control device 700 can be used to execute the functions of the controller in FIG. 2, FIG. 3, FIG. 6, and FIG. 9, or execute the functions of the respective control units in FIG. 2, FIG. 3, FIG. .
  • the present application also provides an MPPT combiner box, including the aforementioned resonant switching capacitor RSCC.
  • the present application further provides a power supply system, including the aforementioned resonant switching capacitor RSCC.
  • a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer.
  • an application running on a computing device and the computing device can be components.
  • One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers.
  • these components can execute from various computer readable media having various data structures stored thereon.
  • a component may, for example, be based on a signal having one or more packets of data (e.g., data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet via a signal interacting with other systems). Communicate through local and/or remote processes.
  • packets of data e.g., data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet via a signal interacting with other systems.
  • the disclosed systems, devices and methods may be implemented in other ways.
  • the device 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 can be combined or May be integrated into another system, or some features may be ignored, or not implemented.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.
  • the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium.
  • the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disc and other media that can store program codes. .

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Abstract

本申请提供了一种谐振开关电容变换器RSCC及其控制方法，该RSCC包括：输入电容和输出电容、N个并联的RSC支路、以及控制器。控制器用于确定N个谐振单元的特征电流的平均值，该特征电流为谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值。在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，充电开关导通时对应的支路处于充电阶段。或，在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，放电开关导通时对应的支路处于放电阶段。本申请提供的RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化。

Description

一种谐振开关电容变换器及其控制方法
本申请要求申请日为2021年5月25日、申请号为202110573323.X、申请名称为“一种谐振开关电容变换器及其控制方法”的中国发明专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电路领域，更具体地，涉及一种谐振开关电容变换器及其控制方法。
背景技术
随着光伏发电、电动汽车、可再生能源系统对电力电子变换器需求的不断增加。传统的直流变换器，普遍采用电感、变压器等磁性元件来传递能量，体积大、功率密度低。同时，这些变换器多工作在硬开关状态，开关损耗大、效率低。
与传统的开关电容变换器相比，谐振开关电容变换器(resonant switched capacitor converter，RSCC)采用谐振单元(谐振电感和谐振电容)传递能量，不仅减小了变换器的体积，同时，其充放电电容均工作在谐振状态，因此不存在电流尖峰问题，可以应用于输出电流较大的场合。
当RSCC中包括多个并联的支路时，其变换功率可以提升，但是由于电路参数的不同，可能导致RSCC中各个支路的电流不均，影响RSCC中的功率开关器件的应力和损耗。
发明内容
本申请提供一种谐振开关电容变换器及其控制方法，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化。
第一方面，提供了一种谐振开关电容变换器，包括：输入电容和输出电容，N个并联的谐振开关电容支路，N个谐振开关电容支路中的每个包括开关单元和谐振单元，以及控制器，控制器用于控制开关单元中的开关的导通状态，使得谐振单元在充电阶段从输入电容获取电能，以及使得谐振单元在放电阶段将电能输出至输出电容。其中，控制器还用于：确定N个谐振单元的特征电流的平均值，N个谐振单元与N个谐振开关电容支路一一对应，该特征电流为谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值。在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，其中，在该充电开关导通时，其对应的谐振开关电容支路处于充电阶段。或者，在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，其中，在该放电开关导通时，其对应的谐振开关电容支路处于放电阶段。其中，第一谐振单元是N个谐振单元中的任一个，第一开关单元是第一谐振单元所在的谐振开关电容支路中的开关单元，N为大于1的整数。
具体而言，控制器可以确定一个谐振开关周期内分别流过N个谐振单元的瞬时电流的 有效值或峰值，该有效值或峰值也可以称为特征电流，进一步计算N个特征电流的平均值，该平均值可以理解为每个谐振单元所承受的标准电流。在确定第一谐振单元的特征电流大于平均值时，说明第一开关单元中的开关所承受的电流大于标准电流，控制器可以用于减小充电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于充电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会减小，从而第一开关单元中的开关所承受的应力和损耗将会减小。在确定第一谐振单元的特征电流小于平均值时，说明流过第一开关单元中的开关的电流低于标准电流，控制器可以用于减小放电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会增大，从而第一开关单元中的开关所承受的应力和损耗将会趋向平均化。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
结合第一方面，在一种可能的实现方式中，控制器具体用于：在确定第一谐振单元的特征电流大于平均值且第一谐振单元的特征电流与平均值的差值大于第一阈值时，减小充电开关的控制信号的占空比。或者，在确定第一谐振单元的特征电流小于平均值且第一谐振单元的特征电流与平均值的差值大于第二阈值时，减小放电开关的控制信号的占空比。
结合第一方面，在一种可能的实现方式中，控制器具体用于：检测N个谐振单元的瞬时电流，根据N个谐振单元的瞬时电流确定N个谐振单元的特征电流，并根据N个谐振单元的特征电流计算平均值。
结合第一方面，在一种可能的实现方式中，控制器包括采样单元和控制单元，采样单元具体用于：采集N个谐振单元的瞬时电流信息，并向控制单元发送N个谐振单元的瞬时电流信息。控制单元具体用于：接收N个谐振单元的瞬时电流信息，根据N个谐振单元的瞬时电流信息确定N个谐振单元的特征电流，并根据N个谐振单元的特征电流计算平均值。
结合第一方面，在一种可能的实现方式中，谐振开关电容变换器为两电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，开关单元包括第一开关和第二开关，第一开关为充电开关，第二开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和输入电容的第一端连接，第一开关的第二端和第二开关的第一端、谐振单元的第一端连接，第二开关的第二端和输入电容的第二端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
结合第一方面，在一种可能的实现方式中，谐振开关电容变换器为中点钳位NPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关和第四开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管、第三二极管、第四二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第三二极管的阴极连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第四 二极管的阳极连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第三二极管的阳极、第四二极管的阴极连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
结合第一方面，在一种可能的实现方式中，谐振开关电容变换器为有源中点钳位ANPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关、第四开关、第五开关和第六开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第五开关的第一端连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第六开关的第二端连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第五开关的第二端、第六开关的第一端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
第二方面，提供一种谐振开关电容变换器的控制方法，该谐振开关电容变换器包括：输入电容和输出电容，N个并联的谐振开关电容支路，N个谐振开关电容支路中的每个包括开关单元和谐振单元，以及控制器，控制器用于控制开关单元中的开关的导通状态，使得谐振单元在充电阶段从输入电容获取电能，以及使得谐振单元在放电阶段将电能输出至输出电容。该方法包括：控制器确定N个谐振单元的特征电流的平均值，N个谐振单元与N个谐振开关电容支路一一对应，特征电流为谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值。控制器在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，其中，在充电开关导通时，其对应的谐振开关电容支路处于充电阶段。或者，控制器在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，其中，在放电开关导通时，其对应的谐振开关电容支路处于放电阶段。其中，第一谐振单元是N个谐振单元中的任一个，第一开关单元是第一谐振单元所在的谐振开关电容支路中的开关单元，N为大于1的整数。
具体而言，控制器可以确定一个谐振开关周期内分别流过N个谐振单元的瞬时电流的有效值或峰值，该有效值或峰值也可以称为特征电流，进一步计算N个特征电流的平均值，该平均值可以理解为每个谐振单元所承受的标准电流。在确定第一谐振单元的特征电流大于平均值时，说明第一开关单元中的开关所承受的电流大于标准电流，控制器可以用于减小充电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于充电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会减小，从而第一开关单元中的开关所承受的应力和损耗将会减小。在确定第一谐振单元的特征电流小于平均值时，说明流过第一开关单元中的开关的电流低于标准电流，控制器可以用于减小放电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会增大，从而第一开关单元中的开关所承受的应力和损耗将会趋向平均化。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均 流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
结合第二方面，在二种可能的实现方式中，控制器在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，包括：控制器在确定第一谐振单元的特征电流大于平均值且第一谐振单元的电流与平均值的差值大于第一阈值时，减小充电开关的控制信号的占空比。控制器在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，包括：控制器在确定第一谐振单元的特征电流小于平均值且第一谐振单元的电流与平均值的差值大于第二阈值时，减小放电开关的控制信号的占空比。
结合第二方面，在二种可能的实现方式中，控制器确定N个谐振单元的特征电流的平均值，包括：控制器检测N个谐振单元的瞬时电流，根据N个谐振单元的瞬时电流确定N个谐振单元的特征电流，以及根据N个谐振单元的特征电流计算平均值。
结合第二方面，在二种可能的实现方式中，控制器包括采样单元和控制单元，控制器确定N个谐振单元的特征电流的平均值，包括：采样单元采集N个谐振单元的瞬时电流信息，并向控制单元发送N个谐振单元的瞬时电流信息，控制单元接收N个谐振单元的瞬时电流信息，并根据N个谐振单元的瞬时电流信息确定N个谐振单元的电流中的每个的有效值和平均值。
结合第二方面，在二种可能的实现方式中，谐振开关电容变换器为两电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，开关单元包括第一开关和第二开关，第一开关为充电开关，第二开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和输入电容的第一端连接，第一开关的第二端和第二开关的第一端、谐振单元的第一端连接，第二开关的第二端和输入电容的第二端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
结合第二方面，在二种可能的实现方式中，谐振开关电容变换器为中点钳位NPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关和第四开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管、第三二极管、第四二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第三二极管的阴极连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第四二极管的阳极连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第三二极管的阳极、第四二极管的阴极连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
结合第二方面，在二种可能的实现方式中，谐振开关电容变换器为有源中点钳位ANPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关、第四开关、第五开关和第六开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电 容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第五开关的第一端连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第六开关的第二端连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第五开关的第二端、第六开关的第一端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
第三方面，提供一种最大功率点追踪MPPT汇流箱，包括前述第一方面及第一方面中任一种实现方式中的谐振开关变换电容器RSCC。
第四方面，提供一种供电系统，包括前述第一方面及第一方面中任一种实现方式中的谐振开关变换电容器RSCC。
附图说明
图1是本申请的一种应用场景的示意性框图。
图2是本申请提供的一种谐振开关电容变换器RSCC的示意图。
图3是本申请实施例提供的一种两电平RSCC的示意性结构图。
图4是两电平RSCC中主功率电路的开关单元中的开关的控制时序。
图5是两电平RSCC中一个谐振开关周期内谐振单元的瞬时电流的变化示意图。
图6是本申请实施例提供的一种NPC型三电平RSCC的示意性结构图。
图7是NPC型三电平RSCC中主功率电路的开关单元中的开关的控制时序。
图8是NPC型三电平RSCC中一个谐振开关周期内谐振单元的瞬时电流的变化示意图。
图9是本申请实施例提供的一种ANPC型三电平RSCC的示意性结构图。
图10是ANPC型三电平RSCC中主功率电路的开关单元中的开关的控制时序。
图11是ANPC型三电平RSCC中一个谐振开关周期内谐振单元的瞬时电流的变化示意图。
图12是本申请提供的一种谐振开关电容变换器的控制方法的示意图。
图13是本申请实施例的控制设备的结构示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
图1是本申请的一种应用场景的示意性框图。如图1所示，本申请的谐振开关电容变换器(resonant switched capacitor converter，RSCC)可以用于供电系统100中，供电系统100可以产生电能，并向电网供电。具体地，供电系统100可以包括供电模块110、最大功率点跟踪(maximum power point tracking，MPPT)汇流箱120、逆变电路130。其中，MPPT汇流箱120可以包括直流-直流升压电路121、直流-直流升压电路122和RSCC123。其中，直流-直流升压电路121的正输出端和逆变电路130的正输入端相连，直流-直流升压电路121的负输出端与逆变电路130的输入端零点相连。直流-直流升压电路122的正输出端和RSCC 123的正输入端相连，直流-直流升压电路122的负输出端与RSCC 123的 负输入端相连。RSCC 123的正输出端和逆变电路130的输入端零点相连，RSCC 123的负输出端和逆变电路130的负输入端相连。换言之，RSCC 123可以将直流-直流升压电路2输出的正电压转换为负电压，然后与直流-直流升压电路1输出的电压串联后一起接入逆变电路130。
供电模块110可以将产生的电能输出至MPPT汇流箱120，MPPT汇流箱120可以在进行直流电压转换之后，将直流电输出至逆变电路130，逆变电路130可以将直流电转换为交流电，并将交流电输出至电网。作为示例，提供电能的供电模块110可以包括但不限于光伏(photovoltaic，PV)组串和/或电池。应理解，供电模块110中的光伏组串/电池111与光伏组串/电池112可以均相同，即均为光伏组串或电池，或者，111和112也可以不同，即111和112一个为电池，一个为光伏组串，本申请不做限定。
可选地，在图1中，直流-直流升压电路121的负输出端也可以接入RSCC 123的负输出端，即直流-直流升压电路121的负输出端和直流-直流升压电路122的负输出端是等电位的。
还应理解，如图1所示，组成供电系统100的供电模块110也可以是一个，也可以是多个，每个供电模块可以相同，也可以不同。与之对应的，组成供电系统100的MPPT汇流箱120也是一个，也可以是多个。即可以将多个供电模块110产生的电能经过多个MPPT汇流箱120的直流电压转换后，输入逆变电路130。应理解，多个供电模块110可以都相同，也可以不同，多个MPPT汇流箱可以都相同，也可以不同，本申请不做限定。
可选地，图1中的供电系统100中还可以包括变压器，其用于接收逆变单元130输出的交流电，并将该交流电进行电压变换，然后输入电网之中。
下面结合图2至图11对本申请实施例提供的RSCC进行说明。
图2是本申请提供的一种谐振开关电容变换器RSCC 200的示意图，如图2所示，谐振开关电容变换器RSCC 200可以包括主功率电路210和控制器220，其中，主动率电路210可以包括输入电容Cin、输出电容Cout以及N个并联的谐振开关电容(resonant switched capacitor，RSC)支路x(x＝1，2，3，……，N)，该N个RSC支路中的每一个都包括开关单元x和谐振单元x。输入电容Cin的两端分别接入主功率电路210的输入端的两端，即图2中的BUS+端和0端，输出电容Cout的两端分别接入主功率电路210的输出端的两端，即图2中的0端和BUS-端。其中，输入电容Cin可以是一个电容，也可以由两个或两个以上的电容串联形成。
应理解，当本申请实施例提供的RSCC应用于图1的供电系统100时，可以将主功率电路220的第一输入端(对应图中BUS+端)作为RSCC 123的正输入端、主功率电路220的第二输入端(对应图中的0端)作为RSCC 123的负输入端，将主功率电路220的第一输出端(对应图中0端)作为RSCC 123的正输出端、主功率电路220的第二输出端(对应图中的BUS-端)作为RSCC 123的负输出端。
换言之，本申请实施例提供的RSCC也可以用于其他场景，例如，可以将主功率电路220的第一输入端(对应图中BUS+端)作为RSCC 123的正输出端、主功率电路220的第二输出端(对应图中的BUS-端)作为RSCC 123的负输出端。在实际应用中，BUS+端、0端和BUS-端具体哪两端作为RSCC 123的正、负输出端可以视实际应用环境而定，本申请实施例不做限定，图1仅仅是对本申请实施例的一种应用场景的示例性说明。
在图2所示的RSCC 200中，控制器220可以控制开关单元x中的开关的导通状态，使得谐振单元x在充电阶段从输入电容Cin获取电能，以及使得谐振单元x在放电阶段将电能输出至输出电容Cout。需要说明的是，每一个开关单元x中包括充电开关x和放电开关x，其中充电开关x的导通时长可以决定谐振单元x从输入电容Cin获取电能的时长，即在充电开关x导通时，该充电开关x所在的RSC支路x处于充电阶段。放电开关x的导通时长可以决定谐振单元x将电能输出至输出电容Cout的时长，即在放电开关x导通时，该放电x开关所在的RSC支路x处于放电阶段。
一般来说，在其他条件不变的情况下，RSCC的主功率电路并联的RCS支路越多，该RSCC变换功率越大。然而，当主功率电路中存在多个并联的RSC支路时，由于每个支路的电路参数的差异，各个支路中的谐振单元会存在电流不均的现象，使得部分支路中的开关会承受较大的电流，从而影响这些支路中的开关的应力和损耗。
应理解，不超过额定电流的情况下，开关器件的工作电流的大小对其承受的应力影响不大，但是，若工作电流超过额定电流，则会使得开关的承受较大应力，从而产生较大损耗。
有鉴于此，本申请提供一种谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
在本申请提供的RSCC中，控制器220可以用于确定N个谐振单元的特征电流的平均值，N个谐振单元与N个谐振开关电容支路一一对应，该特征电流为任一个谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值。在确定第一谐振单元的特征电流大于平均值时，控制器220可以用于减小第一开关单元中的充电开关的控制信号的占空比，在该充电开关导通时，其对应的RSC支路处于充电阶段。或者，在确定第一谐振单元的特征电流小于平均值时，控制器200可以用于减小第一开关单元中的放电开关的控制信号的占空比，在该放电开关导通时，其对应的RSC支路处于放电阶段。其中，第一谐振单元是N个谐振单元中的任一个，第一开关单元是第一谐振单元所在的谐振开关电容支路中的开关单元。应理解，本申请中，N为大于1的整数。
具体而言，控制器220可以确定一个谐振开关周期内分别流过N个谐振单元的瞬时电流的有效值或峰值，该有效值或峰值也可以称为特征电流，进一步计算N个特征电流的平均值，该平均值可以理解为每个谐振单元所承受的标准电流。在确定第一谐振单元的特征电流大于平均值时，说明第一开关单元中的开关所承受的电流大于标准电流，控制器220可以用于减小充电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于充电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会减小，从而第一开关单元中的开关所承受的应力和损耗将会减小。在确定第一谐振单元的特征电流小于平均值时，说明流过第一开关单元中的开关的电流低于标准电流，控制器220可以用于减小放电开关的控制信号的占空比，通过这种方式，第一谐振单元所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，第一谐振单元的特征电流将会增大，从而第一开关单元中的开关所承受的应力和损耗将会趋向平均化。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应 力和损耗引起的电路故障。
应理解，本申请中，占空比指的是对某一个开关来说，其控制信号在一个脉冲周期内高电平的时间相对于整个脉冲周期所占的比例。例如，对于1秒高电平1秒低电平的脉冲宽度调制波形(pulse width modulation wave，PWM波)，占空比是50％。
还应理解，本申请中，充电开关或放电开关的控制信号的占空比的具体减少量可以根据谐振单元的特征电流与平均值的差值的大小进行闭环调节。当特征电流与平均值的差值较大时，占空比的减小量可以较大，当差值较小时，占空比的减小量可以较小。
在一种可能的实现方式中，控制器220具体可以用于：在确定第一谐振单元的特征电流大于平均值且第一谐振单元的特征电流与平均值的差值大于第一阈值时，减小充电开关的控制信号的占空比。或者，在确定第一谐振单元的特征电流小于平均值且第一谐振单元的特征电流与平均值的差值大于第二阈值时，减小放电开关的控制信号的占空比。
换言之，本申请中，控制器220可以在第一谐振单元的特征电流与平均值的差值大于一定阈值时，对充电开关或放电开关的控制信号的占空比进行调节，可以避免因为电路中电流的波动而进行不必要的控制，提高RSCC的控制效率。
在一种可能的实现方式中，控制器220具体用于：检测N个谐振单元的瞬时电流，并根据N个谐振单元的瞬时电流确定N个谐振单元的特征电流，进一步根据N个谐振单元的特征电流计算平均值。
本申请中，控制器220可以实时检测谐振单元的瞬时电流，获得谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值，进一步根据N个谐振单元的有效值或峰值计算平均值。
因此，本申请可以实时检测各个支路的谐振单元的瞬时电流，并将检测结果用于对主功率电路210的进一步控制，从而可以实现主功率电路的闭环调节，提升RSCC的控制效率。
在一种可能的实现方式中，控制器包括采样单元和控制单元，采样单元具体可以用于：采集N个谐振单元的瞬时电流信息，并向控制单元发送N个谐振单元的瞬时电流信息。控制单元具体可以用于：接收N个谐振单元的瞬时电流信息，根据N个谐振单元的瞬时电流信息确定N个谐振单元的特征电流，并根据N个谐振单元的特征电流计算平均值。
在本申请实施例中，控制器220的功能可以由采样单元和控制单元分别实现，因此，本申请实施例可以在现有产品架构基础上实现RSCC中各个并联支路的均流目的，减少成本。
作为示例，图3是本申请实施例提供的一种两电平RSCC 300的示意性结构图。如图3所示，RSCC 300包括主功率电路310和控制器320，主功率电路310为两电平电路拓扑。应理解，图3仅以主功率电路310包括两个RSC支路(即支路10-1和支路10-2)进行说明，但是图3所示的RSCC也可以包括3个或3个以上的相同或不同的支路。
如图3所示，主功率电路310包括输入电容Cin、输出电容Cout、以及支路10-1和10-2。输入电容Cin的两端分别接入主功率电路310的输入端的两端，即图3中的BUS+端和0端，输出电容Cout的两端分别接入主功率电路310的输出端的两端，即图3中的0端和BUS-端。支路10-1和支路10-2均包括开关单元11、谐振单元12以及二极管D1(即第一二极管)、D2(即第二二极管)。开关单元11包括两个功率开关器件S1(即第一开 关)和S2(即第二开关)，谐振单元12包括串联连接的谐振电容器Cr和谐振电感Lr。
在图3所示的主功率电路310中，开关S1的第一端和输入电容Cin的第一端连接，开关S1的第二端和开关S2的第一端、谐振单元12的第一端连接，开关S2的第二端和输入电容的第二端连接。谐振单元12的第二端和D1的阳极、D2的阴极连接，D1的阴极和输出电容Cout的第一端连接，D2的阳极和输出电容Cout的第二端连接。
图4示出了控制器320对主功率电路310的开关单元11中的开关的控制时序。对于支路10-1来说，初始状态下S1、S2、S3、S4均为关断状态。t1时刻，S1导通，S2保持不变。t 1-t 2时刻，S1持续导通，S2持续关断。t 2时刻，S1关断。t 3时刻，S2导通。t 3-t 4时刻，S1持续关断，S2持续导通。t 4时刻S2关断。t 4时刻之后，主功率电路310回到初始阶段。t 1-t 4可以称为一个谐振开关周期。
在S1导通且S2关断时，电流流向为BUS+端、S1、谐振单元12、D1、0端，支路10-1处于充电阶段，输入电容Cin向谐振电容Cr充电。在S1关断且S2导通时，电流流向为谐振单元12、S2、0端、Cout、BUS-端、D2，支路10-1处于放电阶段，谐振电容Cr作为电源向输出电容Cout充电。换言之，控制器320可以对主功率电路310中的开关单元11的导通状态进行控制，从而使得任一个谐振单元x可以在充电阶段从输入电容Cin获取电能，并在放电阶段将电能输出至输出电容Cout。
图5是一个谐振开关周期内流过支路10-1中谐振单元12的瞬时电流的变化示意图。从图4和图5可以看出，支路10-1在充电阶段和放电阶段，流过谐振单元的瞬时电流的方向相反。而开关S1导通的时间t 1-t 2的长度决定了谐振电容Cr充电的时间长度，开关S2导通的时间t 3-t 4的长度决定了谐振电容Cr放电的时间长度。因此，S1也可以称为充电开关，在其导通时，支路10-1处于充电阶段，S2也可以称为放电开关，在其导通时，支路10-1处于放电阶段。
图4和图5以支路10-1为例进行说明，对于支路10-2来说，开关单元11中的开关的控制时序和谐振单元12的瞬时电流变化与支路10-1是一样的。但是，同一时刻对支路10-1和支路10-2的开关单元的11控制内容不一定是相同的，可能在某一时刻，支路10-1处于充电阶段，而支路10-2处于放电阶段。
其中，控制器320可以采集一个谐振开关周期内流过两个谐振单元12的瞬时电流，根据谐振单元12的瞬时电流确定两个谐振单元的特征电流，特征电流可以为一个谐振开关周期内的瞬时电流的峰值，也可以为有效值。进一步根据N个谐振单元的特征电流计算特征电流的算术平均值。
以支路10-1为例，如果确定谐振单元12的特征电流大于平均值，控制器320可以用于减小支路10-1中的开关S1的控制信号的占空比。具体来说，如图4和图5所述，可以将S1的关断时刻提前为t 2’，从而支路10-1处于充电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元12的特征电流将会减小，因此，开关单元11中的开关所承受的应力和损耗将会减小。如果确定谐振单元12的特征电流小于平均值，控制器220可以用于减小开关S2的控制信号的占空比。具体来说，如图4和图5所述，可以将S2的关断时刻提前为t 4’，从而谐振单元12所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元12的特征电流将会增大，因此，开关单元11中的开关所承受的应力和损耗将会趋向平均化。对于其他支路，情况类似，在此不再赘述。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
作为示例，图6是本申请实施例提供的一种中点钳位(neutral point clamped，NPC)型三电平RSCC 400的示意性结构图。如图6所示，RSCC 400包括主功率电路410和控制器420，主功率电路410为NPC型三电平拓扑。应理解，图6仅以主功率电路410包括两个RSC支路(即支路20-1和支路20-2)进行说明，但是图6所示的RSCC也可以包括3个或3个以上相同或不同的支路。
如图6所示，主功率电路410包括输入电容C1(即第一电容)和C2(即第二电容)、输出电容Cout、以及支路20-1和20-2。输入电容C1和C2串联后的两端分别接入主功率电路410的输入端的两端，即图6中的BUS+端和0端，输出电容Cout的两端分别接入主功率电路410的输出端的两端，即图6中的0端和BUS-端。支路20-1和支路20-2均包括开关单元21、谐振单元22以及二极管D1(即第一二极管)、D2(即第二二极管)、D3(即第三二极管)、D4(即第四二极管)。开关单元21包括4个功率开关器件S1(即第一开关)、S2(即第二开关)、S3(即第三开关)、S4(即第四开关)，谐振单元22包括串联连接的谐振电容器Cr和谐振电感Lr。
在图6所示的主功率电路410中，开关S1的第一端和第一电容C1的第一端连接，开关S1的第二端和开关S2的第一端、D3的阴极连接，开关S2的第二端和开关S3的第一端、谐振单元22的第一端连接，开关S3的第二端和开关S4的第一端、D4的阳极连接，开关S4的第二端和第二电容C2的第二端连接，第二电容C2的第一端和第一电容C1的第二端、D3的阳极、D4的阴极连接。谐振单元的第二端和D1的阳极、D2的阴极连接，D1的阴极和输出电容Cout的第一端连接，D2的阳极和输出电容Cout的第二端连接。
图7示出了控制器420对主功率电路410的开关单元21中的开关的控制时序。对于支路20-1来说，初始状态下S1、S2、S4为关断状态、S3为导通状态。t 1时刻，S2导通。t 2时刻，S3关断。t 3时刻，S1导通。t 4时刻，S1关断。t 5时刻，S3导通。t 6时刻，S2关断。t 7时刻，S4导通。t 8时刻，S4关断。t 8时刻电路回到初始状态。t 1-t 8可以称为一个谐振开关周期。
在S1、S2导通且S3、S4关断时，电流流向为BUS+端、S1、S2、谐振单元22、D1、0端，支路20-1处于充电阶段，输入电容C1、C2向谐振电容Cr充电。在S1、S2关断且S3、S4导通时，电流流向为谐振单元22、S3、S4、0端、Cout、BUS-端、D2，支路20-1处于放电阶段，谐振电容Cr作为电源向输出电容Cout充电。换言之，控制器420可以对主功率电路410中的开关单元21的导通状态进行控制，从而使得任一个谐振单元x可以在充电阶段从输入电容Cin获取电能，并在放电阶段将电能输出至输出电容Cout。
图8是一个谐振开关周期内流过支路20-1中谐振单元22的瞬时电流的变化示意图。从图7和图8可以看出，支路20-1在充电阶段和放电阶段，流过谐振单元的瞬时电流的方向相反。开关S1导通的时间t 3-t 4的长度决定了谐振电容充电的时间长度，开关S4导通的时间t 7-t 8的长度决定了谐振电容放电的时间长度。因此，S1也可以称为充电开关，在其导通时，支路21-1处于充电阶段，S4也可以称为放电开关，在其导通时，支路21-1处于放电阶段。
图7和图8以支路20-1为例进行说明，对于支路20-2来说，开关单元21中的开关的控制时序和谐振单元22的瞬时电流变化与支路20-1是一样的。但是，同一时刻对支路20-1和支路20-2的开关单元的21控制内容不一定是相同的，可能在某一时刻，支路20-1处于充电阶段，而支路20-2处于放电阶段。
其中，控制器420可以采集一个谐振开关周期内流过两个谐振单元22的瞬时电流，根据谐振单元22的瞬时电流确定两个谐振单元的特征电流，特征电流可以为一个谐振开关周期内的瞬时电流的峰值，也可以为有效值。进一步根据N个谐振单元的特征电流计算特征电流的算术平均值。
以支路20-1为例，如果确定谐振单元22的特征电流大于平均值，控制器420可以用于减小支路20-1中的开关S1的控制信号的占空比。具体来说，如图7和图8所述，可以将S1的关断时刻提前为t 4’，从而支路20-1处于充电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元22的特征电流将会减小，因此，开关单元21中的开关所承受的应力和损耗将会减小。如果确定谐振单元22的特征电流小于平均值，控制器220可以用于减小开关S4的控制信号的占空比。具体来说，如图7和图8所述，可以将S4的关断时刻提前为t 8’，从而谐振单元22所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元22的特征电流将会增大，因此，开关单元21中的开关所承受的应力和损耗将会趋向平均化。对于其他支路，情况类似，在此不再赘述。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
作为示例，图9是本申请实施例提供的一种有源中点钳位(Active Neutral Point Clamped，ANPC)型三电平RSCC 500的示意性结构图。如图9所示，RSCC 500包括主功率电路510和控制器520，主功率电路510为NPC型三电平拓扑。应理解，图9仅以主功率电路510包括两个RSC支路(即支路30-1和支路30-2)进行说明，但是图9所示的RSCC也可以包括3个或3个以上相同或不同的支路。
如图9所示，主功率电路510包括输入电容C1(即第一电容)和C2(即第二电容)、输出电容Cout、以及支路30-1和30-2。输入电容C1和C2串联后的两端分别接入主功率电路510的输入端的两端，即图9中的BUS+端和0端，输出电容Cout的两端分别接入主功率电路510的输出端的两端，即图9中的0端和BUS-端。支路30-1和支路30-2均包括开关单元31、谐振单元32以及二极管D1(即第一二极管)、D2(即第二二极管)。开关单元31包括两个功率开关器件S1(即第一开关)和S2(即第二开关)，谐振单元12包括串联连接的谐振电容器Cr和谐振电感Lr。
在图9所示的主功率电路510中，开关S1的第一端和第一电容C1的第一端连接，开关S1的第二端和开关S2的第一端、开关S5的第一端连接，开关S2的第二端和开关S3的第一端、谐振单元32的第一端连接，开关S3的第二端和开关S4的第一端、开关S6的第二端连接，开关S4的第二端和第二电容C2的第二端连接，第二电容C2的第一端和第一电容C1的第二端、开关S5的第二端、开关S6的第一端连接。谐振单元32的第二端和D1的阳极、D2的阴极连接，D1的阴极和输出电容Cout的第一端连接，D2的阳极和输出电容Cout的第二端连接。
图10示出了控制器520对主功率电路510的开关单元31中的开关的控制时序。对于支路30-1来说，初始状态下S1、S2、S4、S6为关断状态、S3、S5为导通状态。t 1时刻，S5关断，S6导通。t 2时刻，S2导通，S3关断。t 3时刻，S1导通。t 4时刻，S1关断。t 5时刻，S5导通，S6关断。t 6时刻，S2关断，S3导通。t 7时刻，S4导通。t 8时刻，S4关断，电路回到初始状态。t 1-t 8可以称为一个谐振开关周期。
在S1、S2导通且S3、S4关断时，电流流向为BUS+端、S1、S2、谐振单元32、D1、0端，支路30-1处于充电状态，输入电容C1、C2向谐振电容Cr充电。在S1、S2关断且S3、S4导通时，电流流向为谐振单元32、S3、S4、0端、Cout、BUS-端、D2，支路30-1处于放电状态，谐振电容Cr作为电源向输出电容Cout充电。换言之，控制器520可以对主功率电路510中的开关单元31的导通状态进行控制，从而使得任一个谐振单元x可以在充电阶段从输入电容Cin获取电能，并在放电阶段将电能输出至输出电容Cout。
图11是一个谐振开关周期内流过支路30-1中谐振单元32的瞬时电流的变化示意图。从图11可以看出，支路30-1在充电阶段和放电阶段，流过谐振单元的瞬时电流的方向相反。开关S1导通的时间t 3-t 4的长度决定了谐振电容充电的时间长度，开关S4导通的时间t 7-t 8的长度决定了谐振电容放电的时间长度。因此，S1也可以称为充电开关，在其导通时，支路30-1处于充电阶段，S4也可以称为放电开关，在其导通时，支路10处于放电阶段。
图10和图11以支路30-1为例进行说明，对于支路30-2来说，开关单元31中的开关的控制时序和谐振单元32的瞬时电流变化与支路30-1是一样的。但是，同一时刻对支路30-1和支路30-2的开关单元31控制内容不一定是相同的，可能在某一时刻，支路30-1处于充电阶段，而支路30-2处于放电阶段。
其中，控制器520可以采集一个谐振开关周期内流过两个谐振单元32的瞬时电流，根据谐振单元32的瞬时电流确定两个谐振单元的特征电流，特征电流可以为一个谐振开关周期内的瞬时电流的峰值，也可以为有效值。进一步根据N个谐振单元的特征电流计算特征电流的算术平均值。
以支路30-1为例，如果确定谐振单元32的特征电流大于平均值，控制器520可以用于减小支路30-1中的开关S1的控制信号的占空比。具体来说，如图10和图11所述，可以将S1的关断时刻提前为t 4’，从而支路30-1处于充电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元32的特征电流将会减小，因此，开关单元31中的开关所承受的应力和损耗将会减小。如果确定谐振单元32的特征电流小于平均值，控制器220可以用于减小开关S4的控制信号的占空比。具体来说，如图10和图11所述，可以将S4的关断时刻提前为t 8’，从而谐振单元32所在的支路处于放电阶段的时间将会减小，在下一个谐振开关周期内，谐振单元32的特征电流将会增大，因此，开关单元31中的开关所承受的应力和损耗将会趋向平均化。对于其他支路，情况类似，在此不再赘述。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
应理解，本申请中，RSCC中的N个并联支路可以完全相同，也可以不同，即可以将具有不同拓扑结构的RSC支路并联至主功率电路中。在一种可能的实现方式中，图2中的主功率电路210的输入电容可以由两个电容C1和C2组成，RSC支路1的拓扑结构可 以如图3中的支路10-1所示，RSC支路2的拓扑结构可以如图6中的支路20-1所示，RSC支路3的拓扑结构可以如图9中的支路30所示，本申请实施例对此不做限定。
还应理解，本申请中，控制器220、控制器320、控制器420、控制器520的功能均可以由采样单元和控制单元分别实现，采样单元具体可以用于采集一个谐振开关周期内流过N个谐振单元的瞬时电流信息，并向控制单元发送N个谐振单元的瞬时电流信息。控制单元具体可以用于接收N个谐振单元的瞬时电流信息，根据N个谐振单元的瞬时电流信息确定N个谐振单元的特征电流，进一步根据N个谐振单元的特征电流计算特征电流的算术平均值。
还应理解，特征电流为一个谐振开关周期内流过谐振单元的瞬时电流的有效值或峰值，其中有效值可以根据峰值计算，具体计算方式为峰值乘以根号2。而平均值可以将N个有效值或峰值求和之后除以总个数N。
本申请还提供的一种谐振开关电容变换器的控制方法，该谐振开关电容变换器包括输入电容、输出电容、N个并联的谐振开关电容支路以及控制器。N个谐振开关电容支路中的每个包括开关单元和谐振单元。控制器可以控制开关单元中的开关的导通状态，使得谐振单元在充电阶段从输入电容获取电能，以及使得谐振单元在放电阶段将电能输出至输出电容。
该方法包括：控制器确定N个谐振单元的特征电流的平均值，N个谐振单元与N个谐振开关电容支路一一对应，特征电流为谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值。控制器在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，在该充电开关导通时，其对应的支路处于充电阶段。或者，控制器在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，在该放电开关导通时，其对应的支路处于放电阶段。其中，第一谐振单元是N个谐振单元中的任一个，第一开关单元是第一谐振单元所在的谐振开关电容支路中的开关单元，N为大于1的整数。
因此，本申请提供的谐振开关电容变换器RSCC，能够实现RSCC中各个并联支路均流，从而使得各个支路的开关的应力和损耗均匀化，防止部分支路中的开关承受过高的应力和损耗引起的电路故障。
可选地，控制器在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，包括：控制器在确定第一谐振单元的特征电流大于平均值且第一谐振单元的电流与平均值的差值大于第一阈值时，减小充电开关的控制信号的占空比。
可选地，控制器在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，包括：控制器在确定第一谐振单元的特征电流小于平均值且第一谐振单元的电流与平均值的差值大于第二阈值时，减小放电开关的控制信号的占空比。
可选地，控制器确定N个谐振单元的特征电流的平均值，包括：控制器检测N个谐振单元的瞬时电流，根据N个谐振单元的瞬时电流确定N个谐振单元的特征电流，根据N个谐振单元的特征电流计算平均值。
可选地，控制器包括采样单元和控制单元，控制器确定N个谐振单元的特征电流的平 均值，包括：采样单元采集N个谐振单元的瞬时电流信息，并向控制单元发送N个谐振单元的瞬时电流信息，控制单元接收N个谐振单元的瞬时电流信息，并根据N个谐振单元的瞬时电流信息确定N个谐振单元的电流中的每个的有效值和平均值。
可选地，谐振开关电容变换器为两电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，开关单元包括第一开关和第二开关，第一开关为充电开关，第二开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和输入电容的第一端连接，第一开关的第二端和第二开关的第一端、谐振单元的第一端连接，第二开关的第二端和输入电容的第二端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
可选地，谐振开关电容变换器为中点钳位NPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关和第四开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管、第三二极管、第四二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第三二极管的阴极连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第四二极管的阳极连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第三二极管的阳极、第四二极管的阴极连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
可选地，谐振开关电容变换器为有源中点钳位ANPC型三电平谐振开关电容变换器，谐振单元包括串联连接的谐振电容和谐振电感，输入电容包括第一电容和第二电容，开关单元包括第一开关、第二开关、第三开关、第四开关、第五开关和第六开关，第一开关为充电开关，第四开关为放电开关，N个谐振开关电容支路中的每个还包括第一二极管、第二二极管。第一开关的第一端和第一电容的第一端连接，第一开关的第二端和第二开关的第一端、第五开关的第一端连接，第二开关的第二端和第三开关的第一端、谐振单元的第一端连接，第三开关的第二端和第四开关的第一端、第六开关的第二端连接，第四开关的第二端和第二电容的第二端连接，第二电容的第一端和第一电容的第二端、第五开关的第二端、第六开关的第一端连接。谐振单元的第二端和第一二极管的阳极、第二二极管的阴极连接，第一二极管的阴极和输出电容的第一端连接，第二二极管的阳极和输出电容的第二端连接。
图12是本申请提供的一种谐振开关电容变换器的控制方法的示意图。下面结合图12，对本申请的用于RSCC的控制方法进行描述。
S610：检测N个谐振单元的瞬时电流。
S620：根据N个谐振单元的瞬时电流确定N个谐振单元的特征电流。
S630：根据N个谐振单元的特征电流计算平均值。
S640：在确定第一谐振单元的特征电流大于平均值时，减小第一开关单元中的充电开关的控制信号的占空比，在充电开关导通时，其所在的支路处于充电阶段。
S650：在确定第一谐振单元的特征电流小于平均值时，减小第一开关单元中的放电开关的控制信号的占空比，在放电开关导通时，其所在的支路处于放电阶段。
应理解，S610至S650中每一步的具体实施方式可以参考前文的描述，在此不再赘述。
图13是本申请实施例的控制设备700的结构示意图。如图7所示，该控制设备700包括处理器710、通信接口720。可选地，该控制设备700还可以包括存储器730。可选地，存储器730可以包括于处理器710中。其中，处理器710、通信接口720和存储器730通过内部连接通路互相通信，存储器730用于存储指令，处理器710用于执行存储器730存储的指令，以实现本申请实施例提供的控制方法。可选地，该控制设备700可以用于执行图2、图3、图6、图9中的控制器的功能，或者执行图2、图3、图6、图9中的各个控制单元的功能。
可选地，本申请还提供的一种MPPT汇流箱，包括前述的谐振开关变换电容器RSCC。
可选地，本申请还提供的一种供电系统，包括前述的谐振开关变换电容器RSCC。
在本说明书中使用的术语“部件”、“模块”、“系统”等用于表示计算机相关的实体、硬件、固件、硬件和软件的组合、软件、或执行中的软件。例如，部件可以是但不限于，在处理器上运行的进程、处理器、对象、可执行文件、执行线程、程序和/或计算机。通过图示，在计算设备上运行的应用和计算设备都可以是部件。一个或多个部件可驻留在进程和/或执行线程中，部件可位于一个计算机上和/或分布在2个或更多个计算机之间。此外，这些部件可从在上面存储有各种数据结构的各种计算机可读介质执行。部件可例如根据具有一个或多个数据分组(例如来自与本地系统、分布式系统和/或网络间的另一部件交互的二个部件的数据，例如通过信号与其它系统交互的互联网)的信号通过本地和/或远程进程来通信。
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描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。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。专业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。
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。
所述功能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(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
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 (14)

  1. 一种谐振开关电容变换器，其特征在于，包括：
    输入电容和输出电容；
    N个并联的谐振开关电容支路，所述N个谐振开关电容支路中的每个包括开关单元和谐振单元；
    控制器，所述控制器用于控制所述开关单元中的开关的导通状态，使得所述谐振单元在充电阶段从所述输入电容获取电能，以及使得所述谐振单元在放电阶段将所述电能输出至所述输出电容，
    其中，所述控制器还用于：
    确定N个谐振单元的特征电流的平均值，所述N个谐振单元与所述N个谐振开关电容支路一一对应，所述特征电流为所述谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值；
    在确定第一谐振单元的特征电流大于所述平均值时，减小第一开关单元中的充电开关的控制信号的占空比，其中，在所述充电开关导通时，其对应的谐振开关电容支路处于充电阶段；或者，
    在确定所述第一谐振单元的特征电流小于所述平均值时，减小所述第一开关单元中的放电开关的控制信号的占空比，其中，在所述放电开关导通时，其对应的谐振开关电容支路处于放电阶段；
    其中，所述第一谐振单元是所述N个谐振单元中的任一个，所述第一开关单元是所述第一谐振单元所在的谐振开关电容支路中的开关单元，N为大于1的整数。
  2. 根据权利要求1所述的谐振开关电容变换器，其特征在于，所述控制器具体用于：
    在确定所述第一谐振单元的特征电流大于所述平均值且所述第一谐振单元的特征电流与所述平均值的差值大于第一阈值时，减小所述充电开关的控制信号的占空比；或者，
    在确定所述第一谐振单元的特征电流小于所述平均值且所述第一谐振单元的特征电流与所述平均值的差值大于第二阈值时，减小所述放电开关的控制信号的占空比。
  3. 根据权利要求1或2所述的谐振开关电容变换器，其特征在于，所述控制器具体用于：
    检测所述N个谐振单元的瞬时电流；
    根据所述N个谐振单元的瞬时电流确定所述N个谐振单元的特征电流；
    根据所述N个谐振单元的特征电流计算所述平均值。
  4. 根据权利要求1至3中任一项所述的谐振开关电容变换器，其特征在于，所述控制器包括采样单元和控制单元，
    所述采样单元具体用于：采集所述N个谐振单元的瞬时电流信息，并向所述控制单元发送所述N个谐振单元的瞬时电流信息；
    所述控制单元具体用于：
    接收所述N个谐振单元的瞬时电流信息；
    根据所述N个谐振单元的瞬时电流信息确定所述N个谐振单元的特征电流；
    根据所述N个谐振单元的特征电流计算所述平均值。
  5. 根据权利要求1至4中任一项所述的谐振开关电容变换器，其特征在于，所述谐振开关电容变换器为两电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述开关单元包括第一开关和第二开关，所述第一开关为所述充电开关，所述第二开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管；
    所述第一开关的第一端和所述输入电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述谐振单元的第一端连接，所述第二开关的第二端和所述输入电容的第二端连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
  6. 根据权利要求1至4中任一项所述的谐振开关电容变换器，其特征在于，所述谐振开关电容变换器为中点钳位NPC型三电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述输入电容包括第一电容和第二电容，所述开关单元包括第一开关、第二开关、第三开关和第四开关，所述第一开关为所述充电开关，所述第四开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管、第三二极管、第四二极管；
    所述第一开关的第一端和所述第一电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述第三二极管的阴极连接，所述第二开关的第二端和所述第三开关的第一端、所述谐振单元的第一端连接，所述第三开关的第二端和所述第四开关的第一端、所述第四二极管的阳极连接，所述第四开关的第二端和所述第二电容的第二端连接，所述第二电容的第一端和所述第一电容的第二端、所述第三二极管的阳极、所述第四二极管的阴极连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
  7. 根据权利要求1至4中任一项所述的谐振开关电容变换器，其特征在于，所述谐振开关电容变换器为有源中点钳位ANPC型三电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述输入电容包括第一电容和第二电容，所述开关单元包括第一开关、第二开关、第三开关、第四开关、第五开关和第六开关，所述第一开关为所述充电开关，所述第四开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管；
    所述第一开关的第一端和所述第一电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述第五开关的第一端连接，所述第二开关的第二端和所述第三开关的第一端、所述谐振单元的第一端连接，所述第三开关的第二端和所述第四开关的第一端、所述第六开关的第二端连接，所述第四开关的第二端和所述第二电容的第二端连接，所述第二电容的第一端和所述第一电容的第二端、所述第五开关的第二端、所述第六开关的第一端连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
  8. 一种谐振开关电容变换器的控制方法，其特征在于，所述谐振开关电容变换器包括：
    输入电容和输出电容；
    N个并联的谐振开关电容支路，所述N个谐振开关电容支路中的每个包括开关单元和谐振单元；
    控制器，所述控制器用于控制所述开关单元中的开关的导通状态，使得所述谐振单元在充电阶段从所述输入电容获取电能，以及使得所述谐振单元在放电阶段将所述电能输出至所述输出电容，
    所述方法包括：
    所述控制器确定N个谐振单元的特征电流的平均值，所述N个谐振单元与所述N个谐振开关电容支路一一对应，所述特征电流为所述谐振单元在一个谐振开关周期内的瞬时电流的有效值或峰值；
    所述控制器在确定第一谐振单元的特征电流大于所述平均值时，减小第一开关单元中的充电开关的控制信号的占空比，其中，在所述充电开关导通时，其对应的谐振开关电容支路处于充电阶段；或者，
    所述控制器在确定所述第一谐振单元的特征电流小于所述平均值时，减小所述第一开关单元中的放电开关的控制信号的占空比，其中，在所述放电开关导通时，其对应的谐振开关电容支路处于放电阶段；
    其中，所述第一谐振单元是所述N个谐振单元中的任一个，所述第一开关单元是所述第一谐振单元所在的谐振开关电容支路中的开关单元，N为大于1的整数。
  9. 根据权利要求8所述的控制方法，其特征在于，
    所述控制器在确定第一谐振单元的特征电流大于所述平均值时，减小第一开关单元中的充电开关的控制信号的占空比，包括：
    所述控制器在确定所述第一谐振单元的特征电流大于所述平均值且所述第一谐振单元的电流与所述平均值的差值大于第一阈值时，减小所述充电开关的控制信号的占空比；
    所述控制器在确定所述第一谐振单元的特征电流小于所述平均值时，减小所述第一开关单元中的放电开关的控制信号的占空比，包括：
    所述控制器在确定所述第一谐振单元的特征电流小于所述平均值且所述第一谐振单元的电流与所述平均值的差值大于第二阈值时，减小所述放电开关的控制信号的占空比。
  10. 根据权利要求8或9所述的控制方法，其特征在于，所述控制器确定N个谐振单元的特征电流的平均值，包括：
    所述控制器检测所述N个谐振单元的瞬时电流；
    所述控制器根据所述N个谐振单元的瞬时电流确定所述N个谐振单元的特征电流；
    所述控制器根据所述N个谐振单元的特征电流计算所述平均值。
  11. 根据权利要求8至10中任一项所述的控制方法，其特征在于，所述控制器包括采样单元和控制单元，所述控制器确定N个谐振单元的特征电流的平均值，包括：
    所述采样单元采集所述N个谐振单元的瞬时电流信息，并向所述控制单元发送所述N个谐振单元的瞬时电流信息；
    所述控制单元接收所述N个谐振单元的瞬时电流信息，并根据所述N个谐振单元的瞬时电流信息确定所述N个谐振单元的电流中的每个的有效值和所述平均值。
  12. 根据权利要求8至11中任一项所述的控制方法，其特征在于，所述谐振开关电容变换器为两电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述开关单元包括第一开关和第二开关，所述第一开关为所述充电开关，所述第二开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管；
    所述第一开关的第一端和所述输入电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述谐振单元的第一端连接，所述第二开关的第二端和所述输入电容的第二端连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
  13. 根据权利要求8至11中任一项所述的控制方法，其特征在于，所述谐振开关电容变换器为中点钳位NPC型三电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述输入电容包括第一电容和第二电容，所述开关单元包括第一开关、第二开关、第三开关和第四开关，所述第一开关为所述充电开关，所述第四开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管、第三二极管、第四二极管；
    所述第一开关的第一端和所述第一电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述第三二极管的阴极连接，所述第二开关的第二端和所述第三开关的第一端、所述谐振单元的第一端连接，所述第三开关的第二端和所述第四开关的第一端、所述第四二极管的阳极连接，所述第四开关的第二端和所述第二电容的第二端连接，所述第二电容的第一端和所述第一电容的第二端、所述第三二极管的阳极、所述第四二极管的阴极连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
  14. 根据权利要求8至11中任一项所述的控制方法，其特征在于，所述谐振开关电容变换器为有源中点钳位ANPC型三电平谐振开关电容变换器，所述谐振单元包括串联连接的谐振电容和谐振电感，所述输入电容包括第一电容和第二电容，所述开关单元包括第一开关、第二开关、第三开关、第四开关、第五开关和第六开关，所述第一开关为所述充电开关，所述第四开关为所述放电开关，所述N个谐振开关电容支路中的每个还包括第一二极管、第二二极管；
    所述第一开关的第一端和所述第一电容的第一端连接，所述第一开关的第二端和所述第二开关的第一端、所述第五开关的第一端连接，所述第二开关的第二端和所述第三开关的第一端、所述谐振单元的第一端连接，所述第三开关的第二端和所述第四开关的第一端、所述第六开关的第二端连接，所述第四开关的第二端和所述第二电容的第二端连接，所述 第二电容的第一端和所述第一电容的第二端、所述第五开关的第二端、所述第六开关的第一端连接，
    所述谐振单元的第二端和所述第一二极管的阳极、所述第二二极管的阴极连接，所述第一二极管的阴极和所述输出电容的第一端连接，所述第二二极管的阳极和所述输出电容的第二端连接。
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