WO2024088121A1 - 功率变换器及其控制方法 - Google Patents

功率变换器及其控制方法 Download PDF

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Publication number
WO2024088121A1
WO2024088121A1 PCT/CN2023/125115 CN2023125115W WO2024088121A1 WO 2024088121 A1 WO2024088121 A1 WO 2024088121A1 CN 2023125115 W CN2023125115 W CN 2023125115W WO 2024088121 A1 WO2024088121 A1 WO 2024088121A1
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WO
WIPO (PCT)
Prior art keywords
power converter
output
bridge arm
phase bridge
current
Prior art date
Application number
PCT/CN2023/125115
Other languages
English (en)
French (fr)
Inventor
张贺军
卢茂勇
胡于桥
Original Assignee
华为数字能源技术有限公司
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Publication date
Application filed by 华为数字能源技术有限公司 filed Critical 华为数字能源技术有限公司
Priority to EP23847859.8A priority Critical patent/EP4383535A1/en
Publication of WO2024088121A1 publication Critical patent/WO2024088121A1/zh

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • 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

Definitions

  • the present application relates to the field of power supply technology, and in particular to a power converter and a control method thereof.
  • the inverter mainly adopts the circuit structure shown in Figure 1.
  • the inverter includes an input filter inductor L1, an input filter capacitor C1, an output filter inductor L2, an output filter capacitor C2, a bus capacitor C3, and a three-phase bridge arm composed of switch tubes Q11, Q12, Q21, Q22, Q31 and Q32.
  • an inductor current sampling circuit i.e., Hall Cs1
  • an output current sampling circuit i.e., Hall Cs2
  • the inverter samples the inductor current of the output filter inductor L2 and the output current of the inverter through Hall Cs1 and Hall Cs2 respectively, and controls the 6 switch tubes in the three-phase bridge arm according to the inductor current and output current collected above to realize power supply to the AC load.
  • the inductor current of the output filter inductor L2 and the output current of the inverter are obtained by respectively collecting the currents through two current sampling circuits. This method will lead to high circuit cost of the inverter and large area of the printed circuit board (PCB).
  • the present application provides a power converter and a control method thereof, which can reduce the circuit cost of the power converter and reduce the PCB area of the power converter.
  • the present application provides a power converter, which includes an output inductor, an output capacitor, a first current sampling circuit, a first phase bridge arm, a second phase bridge arm, a third phase bridge arm and a controller.
  • the first phase bridge arm, the second phase bridge arm and the third phase bridge arm are connected in parallel with each other; the midpoint of the first phase bridge arm is connected to the first input end of the power converter, the midpoint of the second phase bridge arm is connected to one end of the output capacitor and the second input end of the power converter, and the midpoint of the third phase bridge arm is connected to the other end of the output capacitor through the output inductor; the other end and one end of the output capacitor are respectively connected to the first output end and the second output end of the power converter; the second input end and the second output end of the power converter are both connected to the zero line; the first current sampling circuit is arranged on the connecting line between the midpoint of the second phase bridge arm and one end of the output capacitor, and is used to collect the inductor current of the output in
  • the power converter can obtain the inductor current of the output inductor and the output current of the power converter through the first current sampling circuit, thereby saving the current sampling circuit for collecting the output current, thereby reducing the circuit cost of the power converter and reducing the PCB area of the power converter.
  • the first current sampling circuit includes a primary winding, a secondary winding and an iron core, one end and the other end of the primary winding are respectively connected to the midpoint of the second phase bridge arm and one end of the output capacitor, and the primary winding and the secondary winding are both coupled to the iron core. It can be understood that since the first current sampling circuit The circuit adopts a circuit structure of a primary winding and a secondary winding, so the circuit cost of the power converter can be effectively reduced, and the circuit volume of the power converter can be effectively reduced.
  • the controller is used to obtain the inductor current of the output inductor when the second phase bridge arm and the third phase bridge arm are both in a working state; and obtain the output current of the power converter based on the capacitive current and the inductor current of the output capacitor.
  • the power converter can calculate the output current of the power converter based on the inductor current of the output inductor and the capacitive current of the output capacitor, thereby saving an output current current sampling circuit, thereby reducing the circuit cost of the power converter and reducing the PCB area of the power converter.
  • the power converter further includes a first switch and a second switch, the first input terminal of the power converter is connected to the midpoint of the first phase bridge arm through the first switch, and the other end of the output capacitor is connected to the first output terminal of the power converter through the second switch.
  • the controller is also used to control the first switch to be disconnected and the second switch to be closed before the second phase bridge arm and the third phase bridge arm are both in a working state.
  • the power converter further includes a bypass branch, and the two ends of the bypass branch are respectively connected to the first input end and the first output end of the power converter.
  • the controller is used to obtain the inductor current of the output inductor when the bypass branch is in a working state, and determine the inductor current as the output current of the power converter. It can be understood that when the bypass branch is working, the power converter can still obtain the output current of the power converter through the inductor current of the output inductor collected by the first current sampling circuit, and has strong applicability.
  • the power converter further includes a first switch and a second switch, the first input terminal of the power converter is connected to the midpoint of the first phase bridge arm through the first switch, and the other end of the output capacitor is connected to the first output terminal of the power converter through the second switch.
  • the controller is also used to control the first switch and the second switch to be disconnected before the bypass branch is in a working state. It can be understood that when the bypass branch is working, by controlling the first switch and the second switch to be disconnected, it can be ensured that the inductor current of the output inductor collected by the first current sampling circuit is the output current of the power converter, thereby improving the accuracy of the output current of the power converter.
  • the power converter further includes an input inductor and a second current sampling circuit, the first input terminal of the power converter is connected to the midpoint of the first phase bridge arm through the input inductor, and the second current sampling circuit is arranged on a connecting line between the second input terminal of the power converter and the midpoint of the second phase bridge arm, for collecting the inductor current of the input inductor.
  • the controller is also used to obtain the inductor current of the input inductor when the first phase bridge arm is in a working state.
  • the power converter can not only obtain the inductor current of the output inductor and the output current of the power converter through the first current sampling circuit, but also obtain the inductor current of the input inductor through the second current sampling circuit, and the power converter has various functions.
  • the power converter further includes a first switch and a second switch, the first input end of the power converter is connected to the midpoint of the first phase bridge arm through the first switch and the input inductor in sequence, and the other end of the output capacitor is connected to the first output end of the power converter through the second switch.
  • the controller is also used to control the first switch to be closed and the second switch to be opened before the first phase bridge arm is in the working state.
  • the first phase bridge arm when the first phase bridge arm is in the working state, by controlling the first switch and the second switch to be closed and opened respectively, it can be ensured that the current value collected by the second current sampling circuit is the inductor current of the input inductor, thereby improving the accuracy of the inductor current of the input inductor.
  • the present application provides a control method for a power converter
  • the power converter includes an output inductor, an output capacitor, a first current sampling circuit, a first phase bridge arm, a second phase bridge arm, a third phase bridge arm and a controller.
  • the first phase bridge arm, the second phase bridge arm and the third phase bridge arm are connected in parallel with each other; the midpoint of the first phase bridge arm is connected to the first input end of the power converter, the midpoint of the second phase bridge arm is connected to one end of the output capacitor and the second input end of the power converter, and the midpoint of the third phase bridge arm is connected to the other end of the output capacitor through the output inductor; the other end and one end of the output capacitor are respectively connected to the first output end and the second output end of the power converter; the second input end and the second output end of the power converter are both connected to the zero line; the first current sampling circuit is arranged on the connecting line between the midpoint of the second phase bridge arm and one end of the output capacitor, for collecting the inductor current of the output inductor.
  • the method includes: obtaining the inductor current of the output inductor, and obtaining the output current of the power converter based on the inductor current.
  • the first current sampling circuit includes a primary winding, a secondary winding and an iron core, one end and the other end of the primary winding are respectively connected to the midpoint of the second phase bridge arm and one end of the output capacitor, and the primary winding and the secondary winding are both coupled to the iron core.
  • obtaining the inductor current of the output inductor and obtaining the output current of the power converter based on the inductor current includes: obtaining the inductor current of the output inductor when both the second phase bridge arm and the third phase bridge arm are in working state; obtaining the output current of the power converter based on the capacitor current and the inductor current of the output capacitor.
  • the power converter further includes a first switch and a second switch, the first input end of the power converter is connected to the midpoint of the first phase bridge arm through the first switch, and the other end of the output capacitor is connected to the first output end of the power converter through the second switch.
  • the method further includes: before both the second phase bridge arm and the third phase bridge arm are in a working state, controlling the first switch to be disconnected and the second switch to be closed.
  • the power converter further includes a bypass branch, and two ends of the bypass branch are respectively connected to the first input end and the first output end of the power converter.
  • the method further includes: when the bypass branch is in a working state, obtaining an inductor current of the output inductor, and determining the inductor current as the output current of the power converter.
  • the power converter further includes a first switch and a second switch, the first input end of the power converter is connected to the midpoint of the first phase bridge arm through the first switch, and the other end of the output capacitor is connected to the first output end of the power converter through the second switch.
  • the method further includes: before the bypass branch is in a working state, controlling the first switch and the second switch to be disconnected.
  • the power converter further includes an input inductor and a second current sampling circuit, the first input terminal of the power converter is connected to the midpoint of the first phase bridge arm through the input inductor, and the second current sampling circuit is arranged on a connecting line between the second input terminal of the power converter and the midpoint of the second phase bridge arm, for collecting the inductor current of the input inductor.
  • the method further includes: obtaining the inductor current of the input inductor when the first phase bridge arm is in a working state.
  • the power converter The method further includes: before the first phase bridge arm is in the working state, controlling the first switch to close and the second switch to open.
  • FIG1 is a schematic diagram of the structure of an inverter provided by the prior art
  • FIG2 is a schematic diagram of an application scenario of a power converter provided in the present application.
  • FIG3 is a schematic diagram of a structure of a power converter provided by the present application.
  • FIG4a is another schematic diagram of the structure of the power converter provided by the present application.
  • FIG4b is another schematic diagram of the structure of the power converter provided by the present application.
  • FIG5a is a working principle diagram of a power converter provided by the present application.
  • FIG5b is another working principle diagram of the power converter provided by the present application.
  • FIG6 is another schematic diagram of the structure of the power converter provided by the present application.
  • FIG7 is another schematic diagram of the structure of the power converter provided by the present application.
  • FIG8a is a working principle diagram of a power converter provided by the present application.
  • FIG8b is another working principle diagram of the power converter provided by the present application.
  • FIG. 9 is a schematic flow chart of a control method for a power converter provided in the present application.
  • the power converter provided in this application is suitable for devices with three-phase bridge arm topology such as inverters and uninterrupted power supplies (UPS), and can be applied to different application scenarios, such as photovoltaic power supply scenarios, energy storage power supply scenarios, UPS power supply scenarios, etc.
  • UPS uninterrupted power supplies
  • the following is an example of a UPS power supply scenario.
  • FIG. 2 is a schematic diagram of an application scenario of a power converter provided by the present application.
  • the power converter provided by the present application may be a UPS as shown in FIG. 2, wherein the input and output ends of the UPS are connected to an AC power grid and an AC household appliance, respectively.
  • the UPS includes an output inductor and an output inductor current sampling circuit. After the UPS starts running, the UPS may collect the inductor current of the output inductor through the output inductor current sampling circuit, and calculate the current output current of the UPS based on the inductor current of the output inductor.
  • the UPS controls the three-phase bridge arm in the UPS based on the inductor current of the output inductor and the current output current of the UPS, thereby converting the AC power grid voltage input at its input end into an AC voltage that meets the power requirements of the AC household appliance, thereby realizing power supply to various types of electrical appliances such as AC loads (such as household appliances).
  • the UPS may obtain the output inductor current and the output current of the UPS through the output inductor current sampling circuit, thereby saving a current sampling circuit of the output current, so as to reduce the circuit cost of the UPS and reduce the PCB area of the UPS.
  • the above is only an example of the application scenario of the power converter provided by the present application, not an exhaustive list, and the present application does not limit the application scenario.
  • FIG. 3 is a schematic diagram of a structure of a power converter provided by the present application.
  • the power converter 1 includes an output inductor L1, an output capacitor C1, a first current sampling circuit Cs1, a first phase bridge arm 11, The second phase bridge arm 12, the third phase bridge arm 13 and the controller 14.
  • the switch tube Q11 and the switch tube Q12 are connected in series to form the first phase bridge arm 11, the switch tube Q21 and the switch tube Q22 are connected in series to form the second phase bridge arm 12, and the switch tube Q31 and the switch tube Q32 are connected in series to form the third phase bridge arm 13.
  • the first phase bridge arm 11, the second phase bridge arm 12 and the third phase bridge arm 13 are connected in parallel.
  • the midpoint a1 of the first phase bridge arm 11, that is, the series connection of the switch tube Q11 and the switch tube Q12, is connected to the first input terminal in11 of the power converter 1.
  • the midpoint a2 of the second phase bridge arm 12, that is, the series connection of the switch tube Q21 and the switch tube Q22, is connected to one end of the output capacitor C1 and the second input terminal in12 of the power converter 1.
  • the midpoint a3 of the third phase bridge arm 13, that is, the series connection of the switch tube Q31 and the switch tube Q32, is connected to the other end of the output capacitor C1 through the output inductor L1.
  • the other end and one end of the output capacitor C1 are respectively connected to the first output end out11 and the second output end out12 of the power converter 1.
  • the second input end in12 and the second output end out12 of the power converter 1 are both connected to the neutral line.
  • the first current sampling circuit Cs1 is arranged on the connection line between the midpoint a2 of the second phase bridge arm 12 and one end of the output capacitor C1, and is used to collect the inductor current of the output inductor L1.
  • the type of the switching tube in the above-mentioned three-phase bridge arm can be a metal oxide semiconductor field effect transistor (metal-oxide-semiconductor Field-Effect-Transistor, MOSFET), an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) or a gallium nitride (Gallium Nitride, GaN) transistor, etc., and this application does not impose any restrictions on this.
  • MOSFET metal-oxide-semiconductor Field-Effect-Transistor
  • IGBT Insulated Gate Bipolar Transistor
  • GaN gallium nitride
  • the controller 14 obtains the inductor current of the output inductor L1 through the first current sampling circuit Cs1 , and obtains the output current of the power converter 1 based on the inductor current of the output inductor L1 .
  • the power converter 1 can obtain the inductor current of the output inductor L1 and the output current of the power converter 1 through the first current sampling circuit Cs1, thereby saving an output current current sampling circuit to reduce the circuit cost of the power converter 1 and reduce the PCB area of the power converter 1.
  • FIG. 4a is another schematic diagram of the structure of the power converter provided by the present application.
  • the power converter 1 includes an output inductor L1, an output capacitor C1, a first current sampling circuit Cs1, a first phase bridge arm 11, a second phase bridge arm 12, a third phase bridge arm 13, a controller 14, a bus capacitor C2, a first switch S1 and a second switch S2.
  • the bus capacitor C2 is connected in parallel at both ends of the first phase bridge arm 11, the first input terminal in11 of the power converter 1 is connected to the midpoint a1 of the first phase bridge arm 11 through the first switch S1, and the other end of the output capacitor C1 is connected to the first output terminal out11 of the power converter 1 through the second switch S2.
  • the first input terminal in11 and the first output terminal out11 of the power converter 1 are both connected to the live wire, and the second input terminal in12 and the second output terminal out12 are both connected to the same neutral wire. Based on this, it can be obtained that the first current sampling circuit Cs1 is located on the neutral wire.
  • the first current sampling circuit Cs1 may adopt a circuit structure of a primary winding and a secondary winding, and specifically refer to the power converter 1 shown in FIG4b .
  • the first current sampling circuit Cs1 includes a primary winding Np, a secondary winding Ns, and an iron core T.
  • One end and the other end of the primary winding Np are respectively connected to the midpoint a2 of the second phase bridge arm 12 and one end of the output capacitor C1, and the primary winding Np and the secondary winding Ns are both coupled to the iron core T.
  • the controller 14 controls the first switch S1 and the second switch S2 to be in a closed state and an open state respectively. After the first switch S1 and the second switch S2 are in a closed state and an open state respectively, the controller 14 The first phase bridge arm 11 is controlled to be in a working state so that the bus capacitor C2 is in a charging state. Afterwards, after the voltage of the bus capacitor C2 reaches the first voltage, the controller 14 controls the first phase bridge arm 11 to stop working, and controls the first switch S1 to be in a disconnected state.
  • the specific implementation method of the first phase bridge arm 11 being in a working state refers to the description of the subsequent embodiments, which will not be described in detail here.
  • the controller 14 controls the second switch S2 to turn on, and after the first switch S1 and the second switch S2 are respectively in the open state and the closed state, the controller 14 controls the two switch tubes located at the diagonal position in the second phase bridge arm 12 and the third phase bridge arm 13 to turn on at the same time, and the two switch tubes of the second phase bridge arm 12 and the third phase bridge arm 13 are respectively turned on complementarily, so that the second phase bridge arm 12 and the third phase bridge arm 13 are both in working state. Specifically, the controller 14 controls the switch tubes Q21, Q22, Q31 and Q32 to turn off, turn on, turn on and turn off the first preset time period respectively. During the first preset time period, the output inductor L1 is in a charging state.
  • the current flows out from the bus capacitor C2 and passes through the switch tube Q31 and the output inductor L1 in sequence. After the current passes through the output inductor L1, part of the current flows through the output capacitor C1, and the other part of the current flows through the AC load connected to an output terminal of the power converter 1. Thereafter, the above two parts of the current flow through the first current sampling circuit Cs1 and the switch tube Q22 in sequence and then flow into the bus capacitor C2. After the switch tubes Q31 and Q22 are turned on and the switch tubes Q21 and Q32 are turned off for the first preset time, the controller 14 controls the switch tubes Q21, Q22, Q31 and Q32 to be turned on, turned off, turned off and turned on for the second preset time respectively.
  • the output inductor L1 is in a discharge state.
  • the first current sampling circuit Cs1 the parasitic diode of the switch tube Q21, the bus capacitor C2 and the parasitic diode of the switch tube Q32 in sequence and then flow into the output inductor L1.
  • the first preset time and the second preset time constitute a working cycle of the second phase bridge arm 12 and the third phase bridge arm 13, and the second phase bridge arm 12 and the third phase bridge arm 13 are both in a working state during the working cycle.
  • the controller 14 sends a current acquisition instruction to the first current sampling circuit Cs1, and the first current sampling circuit Cs1 sends the current at both ends of the secondary winding Ns, that is, the inductor current of the output inductor L1, to the controller 14 according to the received current acquisition instruction.
  • the inductor current of the output inductor L1 collected by the first current sampling circuit Cs1 is composed of the capacitor current of the output capacitor C1 and the output current of the power converter 1.
  • the controller 14 obtains the voltage of the output capacitor C1, and calculates the capacitive current of the output capacitor C1 based on the voltage of the output capacitor C1, thereby calculating the output current of the power converter 1 as the difference between the inductor current of the output inductor L1 collected by the first current sampling circuit Cs1 and the capacitive current of the output capacitor C1.
  • the power converter 1 can obtain the inductor current of the output inductor L1 through the first current sampling circuit Cs1, and calculate the output current of the power converter 1 based on the inductor current of the output inductor L1 and the capacitor current of the output capacitor C1, thereby saving an output current current sampling circuit to reduce the circuit cost of the power converter 1 and reduce the PCB area of the power converter 1.
  • FIG. 6 is another schematic diagram of the structure of the power converter provided by the present application.
  • the power converter 1 shown in FIG. 6 has a bypass branch 15.
  • the bypass branch 15 includes reverse blocking triode thyristors VT1 and VT2, wherein the cathode of the reverse blocking triode thyristor VT1 is The anode of the reverse blocking triode thyristor VT2 is connected to the anode of the reverse blocking triode thyristor VT2 to form one end of the bypass branch 15, and the anode of the reverse blocking triode thyristor VT1 is connected to the cathode of the reverse blocking triode thyristor VT2 to form the other end of the bypass branch 15.
  • bypass branch 15 One end and the other end of the bypass branch 15 are respectively connected to the first input terminal in11 and the first output terminal out11 of the power converter 1.
  • connection relationship between other circuit elements except the bypass branch 15 and other circuit elements please refer to the description of the power converter 1 shown in Figures 4a and 4b, which will not be repeated here.
  • the power converter 1 can also work in the bypass mode.
  • the specific implementation method of determining the output current of the power converter 1 when the power converter 1 works in the inverter mode is no longer described.
  • the controller 14 controls the first switch S1 and the second switch S2 to be turned off, and controls the reverse blocking triode thyristor VT2 to be turned on, so that the power converter 1 is in the bypass mode.
  • the current flows in from the first input terminal in11 of the power converter 1, flows through the reverse blocking triode thyristor VT2, the first output terminal out11 of the power converter 1, the AC load connected to the power converter 1, the second output terminal out12 of the power converter 1 and the first current sampling circuit Cs1, and flows into the second input terminal in12 of the power converter 1.
  • the controller 14 After the power converter 1 is in the bypass mode, the controller 14 sends a current acquisition instruction to the first current sampling circuit Cs1. According to the received current acquisition instruction, the first current sampling circuit Cs1 sends the current at both ends of the secondary winding Ns, that is, the collected inductor current of the output inductor L1, to the controller 14. Since the current flowing out of the output inductor L1 only passes through the AC load connected to the output end of the power converter 1 when the power converter 1 is in the bypass mode, the controller 14 determines the inductor current of the output inductor L1 collected by the first current sampling circuit Cs1 as the output current of the power converter 1.
  • the power converter 1 can obtain the inductor current of the output inductor L1 through the first current sampling circuit Cs1, and calculate the output current of the power converter 1 based on the inductor current of the output inductor L1 and the capacitor current of the output capacitor C1, thereby saving an output current current sampling circuit to reduce the circuit cost of the power converter 1 and reduce the PCB area of the power converter 1.
  • FIG. 7 is another structural schematic diagram of a power converter provided by the present application.
  • the power converter 1 shown in FIG. 7 has an input inductor L2, an input capacitor C3, and a second current sampling circuit Cs2, wherein the first input terminal in11 of the power converter 1 is connected to the midpoint a1 of the first phase bridge arm 11 through the first switch S1 and the input inductor L2 in sequence.
  • the two ends of the input capacitor C3 are respectively connected to the first input terminal in11 and the second input terminal in12 of the power converter 1.
  • the second current sampling circuit Cs2 is arranged on the connecting line between the second input terminal in12 of the power converter 1 and the midpoint a2 of the second phase bridge arm 12, and is used to collect the inductor current of the input inductor L2.
  • the connection relationship between other circuit elements except the input inductor L2, the input capacitor C3 and the second current sampling circuit Cs2 and other circuit elements is referred to the description in the power converter 1 shown in FIG. 6, which will not be repeated here.
  • the second current sampling circuit Cs2 can use a current sensor with the same circuit structure as the first current sampling circuit Cs1, that is, a current sensor with a primary winding and a secondary winding, or it can use a current sensor with a circuit structure different from that of the first current sampling circuit Cs1, and the present application does not impose any restrictions on this.
  • the first input terminal in11 and the second input terminal in12 of the power converter 1 are connected
  • the controller 14 controls the first switch S1 and the second switch S2 to be in the closed state and the closed state respectively, and after the first switch S1 and the second switch S2 are in the closed state and the closed state respectively, the controller 14 controls the switch tubes Q11 and Q12 of the first phase bridge arm 11 to be complementary turned on, so that the first phase bridge arm 11 is in the working state.
  • the controller 14 controls the switch tube Q12 to be turned on for a third preset time length. During the third preset time length, the input inductor L2 is in a charging state.
  • the input inductor L2 discharges to the bus capacitor C2.
  • the bus capacitor C2 As shown in FIG8b, since the direction of the inductor current cannot change suddenly, after the current flows out of the input inductor L2, it flows through the parasitic diode of the switch tube Q11, the bus capacitor C2, the parasitic diode of the switch tube Q22 and the second current sampling circuit Cs2 in sequence and then flows into the second input terminal in12 of the power converter 1.
  • the third preset time and the fourth preset time constitute a working cycle of the first phase bridge arm 11, and the first phase bridge arm 11 is in a working state during the working cycle.
  • the controller 14 sends a current acquisition instruction to the second current sampling circuit Cs2, and the second current sampling circuit Cs2 starts to collect the inductor current of the input inductor L2 according to the received current acquisition instruction, and sends the collected inductor current of the input inductor L2 to the controller 14. Since the first phase bridge arm 11 is in the working state, and when the first switch S1 and the second switch S2 are closed and opened respectively, the current flowing through the second current sampling circuit Cs2 is the current of the input inductor L2, and therefore, the current value collected by the second current sampling circuit Cs2 is the inductor current of the input inductor L2.
  • the controller 14 controls the first phase bridge arm 11 to stop working, and controls the first switch S1 to be disconnected. After the first phase bridge arm 11 stops working and the first switch S1 is in the disconnected state, the controller 14 controls the second switch S2 to be turned on, and after the first switch S1 and the second switch S2 are in the disconnected state and the closed state respectively, the controller 14 controls the second phase bridge arm 12 and the third phase bridge arm 13 to be in the working state.
  • the controller 14 sends a current acquisition instruction to the first current sampling circuit Cs1, and the first current sampling circuit Cs1 starts to collect the inductor current of the output inductor L1 according to the received current acquisition instruction, and sends the collected inductor current of the output inductor L1 to the controller 14.
  • the controller 14 obtains the voltage of the output capacitor C1, and calculates the capacitive current of the output capacitor C1 based on the voltage of the output capacitor C1, thereby calculating the output current of the power converter 1 as the difference between the inductor current of the output inductor L1 collected by the first current sampling circuit Cs1 and the capacitive current of the output capacitor C1.
  • the power converter 1 when the power converter 1 is in the bypass mode, that is, the first switch S1 and the second switch S2 are both turned off, and the reverse blocking triode thyristor VT1 or VT2 is turned on, the power converter 1 can obtain the output current of the power converter 1 through the first current sampling circuit Cs1.
  • the specific implementation method of obtaining the output current of the power converter 1 when the power converter 1 is in the bypass mode is shown in the description of the corresponding part of the power converter 1 shown in FIG6, which will not be repeated here.
  • the power converter 1 can obtain the inductor current of the output inductor L1 through the first current sampling circuit Cs1, and calculate the output current of the power converter 1 based on the inductor current of the output inductor L1 and the capacitor current of the output capacitor C1, thereby saving an output current current sampling circuit to reduce the power converter. 1 and reduce the circuit cost of the power converter 1 and the PCB area.
  • FIG. 9 is a flow chart of a control method for a power converter provided by the present application.
  • the control method for a power converter provided by an embodiment of the present application is applicable to the controller 14 in the power converter 1 shown in FIG. 3 to FIG. 8 b.
  • the control method for a power converter may include the following steps:
  • the controller in the power converter obtains the inductor current of the output inductor.
  • the controller in the power converter obtains the inductor current of the output inductor.
  • a controller in the power converter obtains the output current of the power converter based on the capacitive current of the output capacitor and the inductive current of the output inductor obtained when both the second phase bridge arm and the third phase bridge arm are in working state.
  • the controller in the power converter determines the inductor current of the output inductor obtained when the bypass branch is in an operating state as the output current of the power converter.
  • the power converter can obtain the inductor current of the output inductor through the first current sampling circuit, and calculate the output current of the power converter based on the inductor current of the output inductor and the capacitor current of the output capacitor, thereby saving a current sampling circuit for the output current, thereby reducing the circuit cost of the power converter and reducing the PCB area of the power converter.

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Abstract

本申请提供了一种功率变换器及其控制方法，该功率变换器包括输出电感、输出电容、第一电流采样电路、第一相桥臂、第二相桥臂、第三相桥臂和控制器。第一相桥臂的中点连接功率变换器的第一输入端，第二相桥臂的中点连接输出电容的一端和功率变换器的第二输入端，第三相桥臂的中点通过输出电感连接输出电容的另一端；输出电容的另一端和一端分别连接功率变换器的第一输出端和第二输出端；功率变换器的第二输入端和第二输出端均连接零线；第一电流采样电路设置在第二相桥臂的中点和输出电容的一端之间的连接线上，用于采集输出电感的电感电流；控制器用于基于输出电感的电感电流获得功率变换器的输出电流。采用本申请，可降低功率变换器的电路成本。

Description

功率变换器及其控制方法
本申请要求于2022年10月29日提交中国国家知识产权局、申请号为202211340732.6、申请名称为“功率变换器及其控制方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电源技术领域，尤其涉及一种功率变换器及其控制方法。
背景技术
目前，逆变器主要采用图1所示的电路结构。如图1所示，逆变器包括输入滤波电感L1、输入滤波电容C1、输出滤波电感L2、输出滤波电容C2、母线电容C3以及由开关管Q11、Q12、Q21、Q22、Q31和Q32构成的三相桥臂。此外，逆变器中还设置了电感电流采样电路(即霍尔Cs1)和输出电流采样电路(即霍尔Cs2)。在逆变器工作时，逆变器分别通过霍尔Cs1和霍尔Cs2采样得到输出滤波电感L2的电感电流和逆变器的输出电流，并根据上述采集到的电感电流和输出电流，控制上述三相桥臂中的6个开关管以实现对交流负载的供电。在上述逆变器中，是通过两个电流采样电路分别采集的方式得到输出滤波电感L2的电感电流和逆变器的输出电流，该方式会导致逆变器的电路成本高、印制电路板(Printed Circuit Board，PCB)面积大。
发明内容
本申请提供了一种功率变换器及其控制方法，可降低功率变换器的电路成本和减小功率变换器的PCB面积。
第一方面，本申请提供了一种功率变换器，该功率变换器包括输出电感、输出电容、第一电流采样电路、第一相桥臂、第二相桥臂、第三相桥臂和控制器。其中：第一相桥臂、第二相桥臂和第三相桥臂相互并联；第一相桥臂的中点连接功率变换器的第一输入端，第二相桥臂的中点连接输出电容的一端和功率变换器的第二输入端，第三相桥臂的中点通过输出电感连接输出电容的另一端；输出电容的另一端和一端分别连接功率变换器的第一输出端和第二输出端；功率变换器的第二输入端和第二输出端均连接零线；第一电流采样电路设置在第二相桥臂的中点和输出电容的一端之间的连接线上，用于采集输出电感的电感电流；控制器用于获得输出电感的电感电流，并基于电感电流获得功率变换器的输出电流。从而，该功率变换器可以通过第一电流采样电路得到输出电感的电感电流和功率变换器的输出电流，进而可节省采集输出电流的电流采样电路，以降低功率变换器的电路成本和减小功率变换器的PCB面积。
结合第一方面，在第一种可能的实施方式中，第一电流采样电路包括原边绕组、副边绕组和铁芯，原边绕组的一端和另一端分别连接第二相桥臂的中点和输出电容的一端，并且原边绕组与副边绕组均耦合于铁芯上。可以理解的，由于第一电流采样电 路采用一个原边绕组和一个副边绕组的电路结构，因此可有效降低功率变换器的电路成本，以及有效减小功率变换器的电路体积。
结合第一方面或者第一方面第一种可能的实施方式，在第二种可能的实施方式中，控制器用于在第二相桥臂和第三相桥臂均处于工作状态的情况下，获得输出电感的电感电流；基于输出电容的电容电流和电感电流获得功率变换器的输出电流。可以理解的，功率变换器可以基于输出电感的电感电流和输出电容的电容电流计算得到功率变换器的输出电流，从而节约一个输出电流的电流采样电路，进而降低功率变换器的电路成本和减小功率变换器的PCB面积。
结合第一方面第二种可能的实施方式，在第三种可能的实施方式中，功率变换器还包括第一开关和第二开关，功率变换器的第一输入端通过第一开关连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出端。控制器还用于在第二相桥臂和第三相桥臂均处于工作状态之前，控制第一开关断开，第二开关闭合。可以理解的，在第二相桥臂和第三相桥臂均处于工作状态时，通过控制第二开关闭合，可以保证第一电流采样电路采集到的输出电感的电感电流中包含有功率变换器的输出电流，从而可以提高后续计算得到的功率变换器的输出电流的准确度。
结合第一方面或者第一方面第一种可能的实施方式，在第四种可能的实施方式中，功率变换器还包括旁路支路，旁路支路的两端分别连接功率变换器的第一输入端和第一输出端。控制器用于在旁路支路处于工作状态的情况下，获得输出电感的电感电流，并将电感电流确定为功率变换器的输出电流。可以理解的，在旁路支路工作时，功率变换器仍可通过第一电流采样电路采集到的输出电感的电感电流获得功率变换器的输出电流，适用性强。
结合第一方面第四种可能的实施方式，在第五种可能的实施方式中，功率变换器还包括第一开关和第二开关，功率变换器的第一输入端通过第一开关连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出端。控制器还用于在旁路支路处于工作状态之前，控制第一开关和第二开关断开。可以理解的，在旁路支路工作时，通过控制第一开关和第二开关均断开，可以保证第一电流采样电路采集到的输出电感的电感电流即为功率变换器的输出电流，从而提高功率变换器的输出电流的准确度。
结合第一方面或者第一方面第一种可能的实施方式，在第六种可能的实施方式中，功率变换器还包括输入电感和第二电流采样电路，功率变换器的第一输入端通过输入电感连接第一相桥臂的中点，第二电流采样电路设置于功率变换器的第二输入端和第二相桥臂的中点之间的连接线上，用于采集输入电感的电感电流。控制器还用于在第一相桥臂处于工作状态的情况下，获得输入电感的电感电流。可以理解的，功率变换器不仅可以通过第一电流采样电路获取输出电感的电感电流和功率变换器的输出电流，还可以通过第二电流采样电路获取输入电感的电感电流，功率变换器的功能多样。
结合第一方面第六种可能的实施方式，在第七种可能的实施方式中，功率变换器还包括第一开关和第二开关，功率变换器的第一输入端依次通过第一开关和输入电感连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出 端。控制器还用于在第一相桥臂处于工作状态之前，控制第一开关闭合，第二开关断开。可以理解的，在第一相桥臂处于工作状态时，通过控制第一开关和第二开关分别闭合和断开，可以保证第二电流采样电路采集到的电流值即为输入电感的电感电流，从而提高输入电感的电感电流的准确度。
第二方面，本申请提供了一种功率变换器的控制方法，该功率变换器包括输出电感、输出电容、第一电流采样电路、第一相桥臂、第二相桥臂、第三相桥臂和控制器。其中，第一相桥臂、第二相桥臂和第三相桥臂相互并联；第一相桥臂的中点连接功率变换器的第一输入端，第二相桥臂的中点连接输出电容的一端和功率变换器的第二输入端，第三相桥臂的中点通过输出电感连接输出电容的另一端；输出电容的另一端和一端分别连接功率变换器的第一输出端和第二输出端；功率变换器的第二输入端和第二输出端均连接零线；第一电流采样电路设置在第二相桥臂的中点和输出电容的一端之间的连接线上，用于采集输出电感的电感电流。该方法包括：获得输出电感的电感电流，并基于电感电流获得功率变换器的输出电流。
结合第二方面，在第一种可能的实施方式中，第一电流采样电路包括原边绕组、副边绕组和铁芯，原边绕组的一端和另一端分别连接第二相桥臂的中点和输出电容的一端，并且原边绕组与副边绕组均耦合于铁芯上。
结合第二方面或者第二方面第一种可能的实施方式，在第二种可能的实施方式中，所述获得输出电感的电感电流，并基于电感电流获得功率变换器的输出电流，包括：在第二相桥臂和第三相桥臂均处于工作状态的情况下，获得输出电感的电感电流；基于输出电容的电容电流和电感电流获得功率变换器的输出电流。
结合第二方面第二种可能的实施方式，在第三种可能的实施方式中，功率变换器还包括第一开关和第二开关，功率变换器的第一输入端通过第一开关连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出端。所述方法还包：还在第二相桥臂和第三相桥臂均处于工作状态之前，控制第一开关断开，第二开关闭合。
结合第二方面或者第二方面第一种可能的实施方式，在第四种可能的实施方式中，功率变换器还包括旁路支路，旁路支路的两端分别连接功率变换器的第一输入端和第一输出端。所述方法还包括：在旁路支路处于工作状态的情况下，获得输出电感的电感电流，并将电感电流确定为功率变换器的输出电流。
结合第二方面第四种可能的实施方式，在第五种可能的实施方式中，功率变换器还包括第一开关和第二开关，功率变换器的第一输入端通过第一开关连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出端。所述方法还包括：在旁路支路处于工作状态之前，控制第一开关和第二开关断开。
结合第二方面或者第二方面第一种可能的实施方式，在第六种可能的实施方式中，功率变换器还包括输入电感和第二电流采样电路，功率变换器的第一输入端通过输入电感连接第一相桥臂的中点，第二电流采样电路设置于功率变换器的第二输入端和第二相桥臂的中点之间的连接线上，用于采集输入电感的电感电流。所述方法还包括：在第一相桥臂处于工作状态的情况下，获得输入电感的电感电流。
结合第二方面第六种可能的实施方式，在第七种可能的实施方式中，功率变换器 还包括第一开关和第二开关，功率变换器的第一输入端依次通过第一开关和输入电感连接第一相桥臂的中点，输出电容的另一端通过第二开关连接功率变换器的第一输出端。所述方法还包括：在第一相桥臂处于工作状态之前，控制第一开关闭合，第二开关断开。
应理解的是，本申请上述多个方面的实现和有益效果可互相参考。
附图说明
图1是现有技术提供的逆变器的结构示意图；
图2是本申请提供的功率变换器的应用场景示意图；
图3是本申请提供的功率变换器的一结构示意图；
图4a是本申请提供的功率变换器的另一结构示意图；
图4b是本申请提供的功率变换器的另一结构示意图；
图5a是本申请提供的功率变换器的一工作原理图；
图5b是本申请提供的功率变换器的另一工作原理图；
图6是本申请提供的功率变换器的另一结构示意图；
图7是本申请提供的功率变换器的又一结构示意图；
图8a是本申请提供的功率变换器的一工作原理图；
图8b是本申请提供的功率变换器的另一工作原理图；
图9是本申请提供的功率变换器的控制方法的一流程示意图。
具体实施方式
本申请提供的功率变换器适用于逆变器、不间断电源(Uninterrupted Power Supply，UPS)等具有三相桥臂拓扑的设备，可适用于不同的应用场景，比如，光伏供电场景、储能供电场景、UPS供电场景等。下面以UPS供电场景为例进行说明。
参见图2，图2是本申请提供的功率变换器的应用场景示意图。在UPS供电场景下，本申请提供的功率变换器可以为图2所示的UPS，该UPS的输入端和输出端分别连接交流电网和交流家用设备。该UPS包括输出电感和输出电感电流采样电路。在UPS开始运行后，UPS可通过输出电感电流采样电路采集得到输出电感的电感电流，并基于输出电感的电感电流计算得到UPS的当前输出电流。之后，UPS基于输出电感的电感电流和UPS的当前输出电流控制UPS中的三相桥臂，从而将其输入端输入的交流电网电压变换为符合交流家用设备用电要求的交流电压，进而实现对交流负载(如家用设备)等多种类型的用电设备进行供电。可以理解的，UPS可通过输出电感电流采样电路得到输出电感电流和UPS的输出电流，从而可节省一个输出电流的电流采样电路，以降低UPS的电路成本和减小UPS的PCB面积。上述只是对本申请提供的功率变换器的应用场景进行示例，而非穷举，本申请不对应用场景进行限制。
下面结合图3至图8b对本申请提供的功率变换器的工作原理进行示例说明。
参见图3，图3是本申请提供的功率变换器的一结构示意图。如图3所示，功率变换器1包括输出电感L1、输出电容C1、第一电流采样电路Cs1、第一相桥臂11、 第二相桥臂12、第三相桥臂13和控制器14。其中，开关管Q11与开关管Q12串联构成第一相桥臂11，开关管Q21与开关管Q22串联构成第二相桥臂12，开关管Q31与开关管Q32串联构成第三相桥臂13。第一相桥臂11、第二相桥臂12和第三相桥臂13相互并联。第一相桥臂11的中点a1，即开关管Q11与开关管Q12的串联连接处，连接功率变换器1的第一输入端in11。第二相桥臂12的中点a2，即开关管Q21与开关管Q22的串联连接处，连接输出电容C1的一端和功率变换器1的第二输入端in12。第三相桥臂13的中点a3，即开关管Q31与开关管Q32的串联连接处，通过输出电感L1连接输出电容C1的另一端。输出电容C1的另一端和一端分别连接功率变换器1的第一输出端out11和第二输出端out12。功率变换器1的第二输入端in12和第二输出端out12均连接零线。第一电流采样电路Cs1设置在第二相桥臂12的中点a2和输出电容C1的一端之间的连接线上，用于采集输出电感L1的电感电流。
需要说明的是，上述三相桥臂中的开关管的类型可以是金属氧化物半导体场效应晶体管(metal-oxide-semiconductor Field-Effect-Transistor，MOSFET)、绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor，IGBT)或者氮化镓(Gallium Nitride，GaN)晶体管等，本申请对此不做限制。
在一可选实施方式中，在功率变换器1开始工作后，控制器14通过第一电流采样电路Cs1获得输出电感L1的电感电流，并基于输出电感L1的电感电流获得功率变换器1的输出电流。
在本申请实施例中，功率变换器1可通过第一电流采样电路Cs1得到输出电感L1的电感电流和功率变换器1的输出电流，从而可节省一个输出电流的电流采样电路，以降低功率变换器1的电路成本和减小功率变换器1的PCB面积。
参见图4a，图4a是本申请提供的功率变换器的另一结构示意图。如图4a所示，功率变换器1包括输出电感L1、输出电容C1、第一电流采样电路Cs1、第一相桥臂11、第二相桥臂12、第三相桥臂13、控制器14、母线电容C2、第一开关S1和第二开关S2。其中，母线电容C2并联在第一相桥臂11的两端，功率变换器1的第一输入端in11通过第一开关S1连接第一相桥臂11的中点a1，输出电容C1的另一端通过第二开关S2连接功率变换器1的第一输出端out11。这里，功率变换器1中除了母线电容C2、第一开关S1和第二开关S2之外的其他电路元件的具体连接关系，请参见图3所示的功率变换器1中对应部分的描述，此处不再赘述。需要说明的是，功率变换器1的第一输入端in11和第一输出端out11均连接火线，第二输入端in12和第二输出端out12均连接同一零线。基于此，可以得到第一电流采样电路Cs1位于零线上。
其中，第一电流采样电路Cs1可以采用一个原边绕组和一个副边绕组的电路结构，具体请参见图4b所示的功率变换器1，如图4b所示，第一电流采样电路Cs1包括原边绕组Np、副边绕组Ns和铁芯T。其中，原边绕组Np的一端和另一端分别连接第二相桥臂12的中点a2和输出电容C1的一端，并且原边绕组Np与副边绕组Ns均耦合于铁芯T上。
在一可选实施方式中，在功率变换器1的第一输入端in11和第二输入端in12接入交流电压后，控制器14控制第一开关S1和第二开关S2分别处于闭合状态和断开状态。并在第一开关S1和第二开关S2分别处于闭合状态和断开状态之后，控制器14 控制第一相桥臂11处于工作状态，以使母线电容C2处于充电状态。之后，在母线电容C2的电压达到第一电压后，控制器14控制第一相桥臂11停止工作，并控制第一开关S1处于断开状态。这里，第一相桥臂11处于工作状态的具体实现方式请参见后续实施例的描述，此处不再展开描述。
之后，控制器14控制第二开关S2导通，并在第一开关S1和第二开关S2分别处于断开状态和闭合状态后，控制器14控制第二相桥臂12和第三相桥臂13中位于对角位置的两个开关管同时导通，第二相桥臂12和第三相桥臂13各自的两个开关管互补导通，以使第二相桥臂12和第三相桥臂13均处于工作状态。具体来讲，控制器14分别控制开关管Q21、Q22、Q31和Q32关断、导通、导通和关断第一预设时长，在第一预设时长内，输出电感L1处于充电状态，如图5a所示，电流从母线电容C2流出依次经过开关管Q31和输出电感L1，在电流经过输出电感L1后，一部分电流流经输出电容C1，另一部分电流流经与功率变换器1的一个输出端相连的交流负载，之后上述两部分电流均依次流经第一电流采样电路Cs1和开关管Q22后流入母线电容C2。并在开关管Q31和Q22导通，且开关管Q21和Q32关断第一预设时长后，控制器14分别控制开关管Q21、Q22、Q31和Q32导通、关断、关断和导通第二预设时长，在第二预设时长内，输出电感L1处于放电状态，如图5b所示，由于电感电流的方向不能突变，因此，电流从输出电感L1流出后，一部分电流流经输出电容C1，另一部分电流流经与功率变换器1输出端相连的交流负载，之后上述两部分电流均依次流经第一电流采样电路Cs1、开关管Q21的寄生二极管、母线电容C2和开关管Q32的寄生二极管后流入输出电感L1。其中，第一预设时长和第二预设时长构成第二相桥臂12和第三相桥臂13的一个工作周期，在该工作周期内第二相桥臂12和第三相桥臂13均处于工作状态。
在第二相桥臂12和第三相桥臂13均处于工作状态的同时，控制器14向第一电流采样电路Cs1发送电流获取指令，第一电流采样电路Cs1根据接收到的电流获取指令，将副边绕组Ns两端的电流，即输出电感L1的电感电流，发送至控制器14。由于第二相桥臂12和第三相桥臂13均处于工作状态，且第一开关S1和第二开关S2分别断开和闭合时，从输出电感L1流出的电流一部分流经输出电容C1，另一部分流经与功率变换器1的输出端相连的交流负载，因此，第一电流采样电路Cs1采集到的输出电感L1的电感电流由输出电容C1的电容电流和功率变换器1的输出电流两部分构成。控制器14获取输出电容C1的电压，并基于输出电容C1的电压计算得到输出电容C1的电容电流，从而计算得到功率变换器1的输出电流为第一电流采样电路Cs1采集到的输出电感L1的电感电流与输出电容C1的电容电流之差。
在本申请实施例中，功率变换器1可通过第一电流采样电路Cs1得到输出电感L1的电感电流，并基于输出电感L1的电感电流和输出电容C1的电容电流计算得到功率变换器1的输出电流，从而可节省一个输出电流的电流采样电路，以降低功率变换器1的电路成本和减小功率变换器1的PCB面积。
参见图6，图6是本申请提供的功率变换器的另一结构示意图。如图6所示，与图4a所示的功率变换器1相比，图6所示的功率变换器1中多了旁路支路15。旁路支路15包括反向阻断三极晶闸管VT1和VT2，其中，反向阻断三极晶闸管VT1的阴 极连接反向阻断三极晶闸管VT2的阳极构成旁路支路15的一端，反向阻断三极晶闸管VT1的阳极连接反向阻断三极晶闸管VT2的阴极构成旁路支路15的另一端，旁路支路15的一端和另一端分别连接功率变换器1的第一输入端in11和第一输出端out11。这里，除旁路支路15之外的其他电路元件以及其他电路元件之间的连接关系请参见图4a和图4b所示的功率变换器1中的描述，此处不再赘述。
功率变换器1除了工作在逆变模式之外，还可以工作在旁路模式。在本实施例中，不再描述功率变换器1工作在逆变模式时确定功率变换器1的输出电流的具体实现方式，详情请参见图4a所示的功率变换器1对应部分的描述，其中，功率变换器1工作在逆变模式也即第二相桥臂12和第三相桥臂13均处于工作状态，且第一开关S1和第二开关S2分别处于断开和闭合状态。
在一可选实施方式中，控制器14控制第一开关S1和第二开关S2均断开，并控制反向阻断三极晶闸管VT2导通，以使功率变换器1处于旁路模式。在功率变换器1处于旁路模式时，电流从功率变换器1的第一输入端in11流入，依次流经反向阻断三极晶闸管VT2、功率变换器1的第一输出端out11、与功率变换器1相连的交流负载、功率变换器1的第二输出端out12和第一电流采样电路Cs1，流入功率变换器1的第二输入端in12。
在功率变换器1处于旁路模式后，控制器14向第一电流采样电路Cs1发送电流获取指令。第一电流采样电路Cs1根据接收到的电流获取指令，将副边绕组Ns两端的电流，即采集到的输出电感L1的电感电流，发送至控制器14。由于在功率变换器1处于旁路模式时从输出电感L1流出的电流只经过与功率变换器1的输出端相连的交流负载，因此，控制器14将获取到的第一电流采样电路Cs1采集到的输出电感L1的电感电流确定为功率变换器1的输出电流。
在本申请实施例中，功率变换器1可通过第一电流采样电路Cs1得到输出电感L1的电感电流，并基于输出电感L1的电感电流和输出电容C1的电容电流计算得到功率变换器1的输出电流，从而可节省一个输出电流的电流采样电路，以降低功率变换器1的电路成本和减小功率变换器1的PCB面积。
参见图7，图7是本申请提供的功率变换器的又一结构示意图。如图7所示，与图6所示的功率变换器1相比，图7所示的功率变换器1中多了输入电感L2、输入电容C3和第二电流采样电路Cs2，其中，功率变换器1的第一输入端in11依次通过第一开关S1和输入电感L2连接第一相桥臂11的中点a1。输入电容C3的两端分别连接功率变换器1的第一输入端in11和第二输入端in12。第二电流采样电路Cs2设置于功率变换器1的第二输入端in12和第二相桥臂12的中点a2之间的连接线上，用于采集输入电感L2的电感电流。这里，除输入电感L2、输入电容C3和第二电流采样电路Cs2之外的其他电路元件以及其他电路元件之间的连接关系请参见图6所示的功率变换器1中的描述，此处不再赘述。
其中，第二电流采样电路Cs2可以采用与第一电流采样电路Cs1相同电路结构的电流传感器，即具有一个原边绕组和一个副边绕组的电流传感器，也可以采用与第一电流采样电路Cs1的电路结构不同的电流传感器，本申请对此不做限制。
在一可选实施方式中，在功率变换器1的第一输入端in11和第二输入端in12接 入交流电压后，控制器14控制第一开关S1和第二开关S2分别处于闭合状态和关断状态，并在第一开关S1和第二开关S2分别处于闭合状态和关断状态后，控制器14控制第一相桥臂11的开关管Q11和Q12互补导通，以使第一相桥臂11处于工作状态。具体来讲，控制器14控制开关管Q12导通第三预设时长，在第三预设时长内，输入电感L2处于充电状态，如图8a所示，电流从功率变换器1的第一输入端in11流入后，一部分电流流经输入电感L2，另一部分电流流经输入电容C3。流经输入电感L2的一部分电流从输入电感L2流出后，依次流经开关管Q12、开关管Q22的寄生电容和第二电流采样电路Cs2后，流入功率变换器1的第二输入端in12。并在开关管Q22导通第三预设时长后，控制器14控制开关管Q11导通第四预设时长，在第四预设时长内，输入电感L2处于放电状态，具体来讲，输入电感L2向母线电容C2放电，如图8b所示，由于电感电流的方向不能突变，因此，电流从输入电感L2流出后，依次流经开关管Q11的寄生二极管、母线电容C2、开关管Q22的寄生二极管和第二电流采样电路Cs2后流入功率变换器1的第二输入端in12。其中，第三预设时长和第四预设时长构成第一相桥臂11的一个工作周期，在该工作周期内第一相桥臂11处于工作状态。
在第一相桥臂11处于工作状态的同时，控制器14向第二电流采样电路Cs2发送电流获取指令，第二电流采样电路Cs2根据接收到的电流获取指令开始采集输入电感L2的电感电流，并将采集到的输入电感L2的电感电流发送至控制器14。由于第一相桥臂11处于工作状态，且第一开关S1和第二开关S2分别闭合和断开时，流经第二电流采样电路Cs2的电流即为输入电感L2的电流，因此，第二电流采样电路Cs2采集到的电流值即为输入电感L2的电感电流。
之后，在母线电容C2的电压达到第一电压后，控制器14控制第一相桥臂11停止工作，并控制第一开关S1断开。在第一相桥臂11停止工作且第一开关S1处于断开状态后，控制器14控制第二开关S2导通，并在第一开关S1和第二开关S2分别处于断开状态和闭合状态后，控制器14控制第二相桥臂12和第三相桥臂13均处于工作状态。在第二相桥臂12和第三相桥臂13均处于工作状态的同时，控制器14向第一电流采样电路Cs1发送电流获取指令，第一电流采样电路Cs1根据接收到的电流获取指令开始采集输出电感L1的电感电流，并将采集到的输出电感L1的电感电流发送至控制器14。控制器14获取输出电容C1的电压，并基于输出电容C1的电压计算得到输出电容C1的电容电流，从而计算得到功率变换器1的输出电流为第一电流采样电路Cs1采集到的输出电感L1的电感电流与输出电容C1的电容电流之差。
此外，在功率变换器1处于旁路模式时，也即第一开关S1和第二开关S2均断开，并且反向阻断三极晶闸管VT1或者VT2导通时，功率变换器1可以通过第一电流采样电路Cs1获取功率变换器1的输出电流。这里，功率变换器1处于旁路模式下获取功率变换器1的输出电流的具体实现方式请参见图6所示的功率变换器1中对应部分的描述，此处不再赘述。
在本申请实施例中，功率变换器1可通过第一电流采样电路Cs1得到输出电感L1的电感电流，并基于输出电感L1的电感电流和输出电容C1的电容电流计算得到功率变换器1的输出电流，从而可节省一个输出电流的电流采样电路，以降低功率变换器 1的电路成本和减小功率变换器1的PCB面积。
参见图9，图9是本申请提供的功率变换器的控制方法的一流程示意图。本申请实施例提供的功率变换器的控制方法适用于图3至图8b所示的功率变换器1中的控制器14。功率变换器的控制方法可包括步骤：
S101，获得输出电感的电感电流。
在一可选实施方式中，在第二相桥臂和第三相桥臂均处于工作状态的情况下，功率变换器中的控制器获得输出电感的电感电流。
在另一可选实施方式中，在旁路支路处于工作状态的情况下，功率变换器中的控制器获得输出电感的电感电流。
S102，基于电感电流获得功率变换器的输出电流。
在一可选实施方式中，功率变换器中的控制器基于输出电容的电容电流和在第二相桥臂和第三相桥臂均处于工作状态的情况下获得的输出电感的电感电流，得到功率变换器的输出电流。
在另一可选实施方式中，功率变换器中的控制器将在旁路支路处于工作状态的情况下获得的输出电感的电感电流确定为功率变换器的输出电流。
具体实现中，本申请提供的功率变换器的控制方法中控制器所执行的更多操作可参见图3至图8b所示的功率变换器1中控制器14所执行的实现方式，在此不再赘述。
本申请实施例中，功率变换器可通过第一电流采样电路得到输出电感的电感电流，并基于输出电感的电感电流和输出电容的电容电流计算得到功率变换器的输出电流，从而可节省一个输出电流的电流采样电路，以降低功率变换器的电路成本和减小功率变换器的PCB面积。
以上，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权利要求的保护范围为准。

Claims (12)

  1. 一种功率变换器，其特征在于，所述功率变换器包括输出电感、输出电容、第一电流采样电路、第一相桥臂、第二相桥臂、第三相桥臂和控制器，其中：
    所述第一相桥臂、所述第二相桥臂和所述第三相桥臂相互并联；
    所述第一相桥臂的中点连接所述功率变换器的第一输入端，所述第二相桥臂的中点连接所述输出电容的一端和所述功率变换器的第二输入端，所述第三相桥臂的中点通过所述输出电感连接所述输出电容的另一端；
    所述输出电容的另一端和一端分别连接所述功率变换器的第一输出端和第二输出端；
    所述功率变换器的第二输入端和第二输出端均连接零线；
    所述第一电流采样电路设置在所述第二相桥臂的中点和所述输出电容的一端之间的连接线上，用于采集所述输出电感的电感电流；
    所述控制器用于获得所述输出电感的电感电流，并基于所述电感电流获得所述功率变换器的输出电流。
  2. 根据权利要求1所述的功率变换器，其特征在于，所述第一电流采样电路包括原边绕组、副边绕组和铁芯，所述原边绕组的一端和另一端分别连接所述第二相桥臂的中点和所述输出电容的一端，并且所述原边绕组与所述副边绕组均耦合于所述铁芯上。
  3. 根据权利要求1或2所述的功率变换器，其特征在于，所述控制器用于在所述第二相桥臂和所述第三相桥臂均处于工作状态的情况下，获得所述输出电感的电感电流；基于所述输出电容的电容电流和所述电感电流获得所述功率变换器的输出电流。
  4. 根据权利要求3所述的功率变换器，其特征在于，所述功率变换器还包括第一开关和第二开关，所述功率变换器的第一输入端通过所述第一开关连接所述第一相桥臂的中点，所述输出电容的另一端通过所述第二开关连接所述功率变换器的第一输出端；
    所述控制器还用于在所述第二相桥臂和所述第三相桥臂均处于工作状态之前，控制所述第一开关断开，所述第二开关闭合。
  5. 根据权利要求1或2所述的功率变换器，其特征在于，所述功率变换器还包括旁路支路，所述旁路支路的两端分别连接所述功率变换器的第一输入端和第一输出端；
    所述控制器用于在所述旁路支路处于工作状态的情况下，获得所述输出电感的电感电流；将所述电感电流确定为所述功率变换器的输出电流。
  6. 根据权利要求5所述的功率变换器，其特征在于，所述功率变换器还包括第一开关和所述第二开关，所述功率变换器的第一输入端通过所述第一开关连接所述第一相桥臂的中点，所述输出电容的另一端通过所述第二开关连接所述功率变换器的第一输出端；
    所述控制器还用于在所述旁路支路处于工作状态之前，控制所述第一开关和所述第二开关断开。
  7. 一种功率变换器的控制方法，其特征在于，所述功率变换器包括输出电感、输出电容、第一电流采样电路、第一相桥臂、第二相桥臂、第三相桥臂和控制器，其中：所述第一相桥臂、所述第二相桥臂和所述第三相桥臂相互并联；所述第一相桥臂的中点连接所述功率变换器的第一输入端，所述第二相桥臂的中点连接所述输出电容的一端和所述功率变换器的第二输入端，所述第三相桥臂的中点通过所述输出电感连接所述输出电容的另一端；所述输出电容的另一端和一端分别连接所述功率变换器的第一输出端和第二输出端；所述功率变换器的第二输入端和第二输出端均连接零线；所述第一电流采样电路设置在所述第二相桥臂的中点和所述输出电容的一端之间的连接线上，用于采集所述输出电感的电感电流；
    所述方法包括：
    获得所述输出电感的电感电流，并基于所述电感电流获得所述功率变换器的输出电流。
  8. 根据权利要求7所述的方法，其特征在于，所述第一电流采样电路包括原边绕组、副边绕组和铁芯，所述原边绕组的一端和另一端分别连接所述第二相桥臂的中点和所述输出电容的一端，并且所述原边绕组与所述副边绕组均耦合于所述铁芯上。
  9. 根据权利要求7或8所述的方法，其特征在于，所述获得所述输出电感的电感电流，并基于所述电感电流获得所述功率变换器的输出电流，包括：
    在所述第二相桥臂和所述第三相桥臂均处于工作状态的情况下，获得所述输出电感的电感电流；
    基于所述输出电容的电容电流和所述电感电流获得所述功率变换器的输出电流。
  10. 根据权利要求9所述的方法，其特征在于，所述功率变换器还包括第一开关和第二开关，所述功率变换器的第一输入端通过所述第一开关连接所述第一相桥臂的中点，所述输出电容的另一端通过所述第二开关连接所述功率变换器的第一输出端；
    所述方法还包括：
    在所述第二相桥臂和所述第三相桥臂均处于工作状态之前，控制所述第一开关断开，所述第二开关闭合。
  11. 根据权利要求7或8所述的方法，其特征在于，所述功率变换器还包括旁路支路，所述旁路支路的两端分别连接所述功率变换器的第一输入端和第一输出端；
    所述获得所述输出电感的电感电流，并基于所述电感电流获得所述功率变换器的输出电流，包括：
    在所述旁路支路处于工作状态的情况下，获得所述输出电感的电感电流；将所述电感电流确定为所述功率变换器的输出电流。
  12. 根据权利要求11所述的方法，其特征在于，所述功率变换器还包括第一开关和所述第二开关，所述功率变换器的第一输入端通过所述第一开关连接所述第一相桥臂的中点，所述输出电容的另一端通过所述第二开关连接所述功率变换器的第一输出端；
    所述方法还包括：
    在所述旁路支路处于工作状态之前，控制所述第一开关和所述第二开关断开。
PCT/CN2023/125115 2022-10-29 2023-10-18 功率变换器及其控制方法 WO2024088121A1 (zh)

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