A flip changeover circuit and a photovoltaic power generation system

Abstract

This application discloses a switching converter circuit and a photovoltaic power generation system. The switching converter circuit includes: multiple input terminals, a half-bridge switching unit, an output capacitor unit, a resonant unit, a series diode unit, an energy storage switching unit, an input unit, an output unit, and a controller. The energy storage switching unit includes at least one switching device and a first diode, with the at least one switching device connected in series with the first diode. The controller is used to: convert the first voltage input to the input unit into a second voltage by controlling the switching devices in the half-bridge switching unit and the energy storage switching unit to be turned on or off, so that the output unit outputs the second voltage. Compared with existing topologies, the switching converter circuit structure provided by this application can reduce the number of diodes in the circuit and reduce the circuit's footprint, thereby reducing the overall circuit loss and cost, and significantly improving the power density.

Description

Technical Field

[0001] This application relates to the field of electronic power, and in particular to a switching converter circuit and a photovoltaic power generation system. Background Technology

[0002] In common high-voltage direct current (HVDC) transmission systems, uninterruptible power supply (UPS) systems, and photovoltaic power generation systems, DC converters are used in the conversion circuits to achieve DC power conversion. Figure 1 In a typical photovoltaic (PV) power generation system, the DC combiner box primarily needs to consider the current carrying capacity of the downstream cables and the cable losses caused by excessive current. Therefore, the DC combiner box needs to reduce the output current while ensuring output power. Specifically, the DC combiner box includes a DC-DC converter circuit and a resonant switched capacitor converter (RSCC) circuit. Figure 1 The four photovoltaic modules in the upper half are connected in parallel with the corresponding DC-DC converters in the DC combiner box, outputting V. BUS+ and V BUS+ Input to the DC bus; Figure 1 The four photovoltaic modules in the lower half are also connected to a DC-DC circuit, which outputs in parallel and is connected to a resonant switched capacitor converter (RSCC) circuit. The RSCC circuit outputs V in parallel. BUS- and V BUS- Output to the DC bus, at point BUSN, V BUS+ With V BUS- By connecting them in series, the total output voltage to the subsequent inverter can be twice V. BUS The voltage is ultimately supplied to critical AC loads (such as the power grid) through the grid-connected cabinet and transformer. Using this method, the DC combiner box can increase the voltage on the DC bus while maintaining the same output power, thereby reducing the output current.

[0003] Figure 2 This is a schematic diagram of the current DC-DC and RSCC circuit topologies. Figure 2 As shown, the DC-DC circuit is used to connect to the photovoltaic module, receive the DC voltage Vin input from the photovoltaic module, and boost the DC voltage Vin input from the photovoltaic module to obtain V.BUS+ V BUS+ The voltage falls onto C1 and C2 connected in series, while the RSCC circuit section is used to connect to the DC-DC circuit, utilizing the V output of the DC-DC circuit. BUS+ , for V BUS+ To achieve the flip, thus obtaining V BUS- V BUS- The voltage drops to capacitor C3, and the total output voltage of the circuit is twice V. BUS However, the above-mentioned solutions use too many semiconductor devices, leading to increased circuit manufacturing costs. Correspondingly, the excessive number of semiconductors also results in higher losses within the circuit, ultimately leading to relatively low conversion efficiency in the DC combiner box and even the entire inverter system. Therefore, effectively reducing the number of semiconductor devices in the DC combiner box is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This application provides a switching converter circuit and a photovoltaic power generation system, which, compared with the existing DC-DC plus RSCC circuit topology, can significantly reduce the number of semiconductor devices, thereby reducing power supply costs, reducing losses and improving conversion efficiency.

[0005] In a first aspect, this application provides a flip-flop converter circuit, comprising: a first input terminal S1, a second input terminal S2, a third input terminal S3, a half-bridge switching unit, an output capacitor unit, a resonant unit, a series diode unit, an energy storage switching unit, an input unit, an output unit, and a controller; the half-bridge switching unit comprises N switching devices, where N is an even number; the half-bridge switching unit is connected between S1 and S2, the series diode unit is connected between S2 and S3, the output capacitor unit is connected in parallel across the series diode unit, the input unit is connected between S1 and S2, and the output unit is connected between S1 and S3; the energy storage switching unit comprises at least one switch. The device includes a first diode D1, and at least one switching device is connected in series with the first diode D1; the resonant unit includes a first capacitor and a first inductor, the first end of the first inductor is connected to the half-bridge switching unit, and the second end of the first capacitor is connected to the series diode unit; the second end of the first inductor is connected to the first end of the first capacitor; one end of the energy storage switching unit is connected between the half-bridge switching unit and the series diode unit, and the other end is connected to the second end of the first inductor; the controller is used to: convert the first voltage input to the input unit into a second voltage by controlling the switching devices in the half-bridge switching unit and the energy storage switching unit to be turned on or off, so that the output unit outputs the second voltage.

[0006] The structure of the switching circuit provided in this application can significantly reduce the cost of components in the circuit, the board space occupied by the entire circuit, and the device losses. In addition, compared with the prior art, the structure provided in this application also significantly reduces the number of diodes, so that the switching devices in the switching circuit have the condition of zero voltage conduction, thereby reducing switching losses.

[0007] The specific number of switching devices in the aforementioned half-bridge switching unit and energy storage switching unit can be related to the magnitude of the first voltage and the withstand voltage capability of the switching devices. When specifically designing the number of switching devices in the half-bridge switching unit and energy storage switching unit, if the first voltage is large and the withstand voltage capability of the switching devices is low, multiple switching devices can be connected in series to divide the first voltage, thereby ensuring that the switching devices with low withstand voltage capability can work normally. As a possible implementation, the half-bridge switching unit includes: a first switching module and a second switching module; the first switching module and the second switching module each contain a switching device; optionally, the first electrode of the switching device in the first switching module is connected to S1, the second electrode of the switching device in the first switching module is connected to the first electrode of the switching device in the second switching module, and the second electrode of the switching device in the second switching module is connected to S2; one end of the first inductor is connected to the second electrode of the switching device in the first switching module.

[0008] As one possible implementation, the half-bridge switching unit includes: a first switching module and a second switching module; the first switching module and the second switching module each include a plurality of switching devices; in the first switching module and the second switching module, each pair of adjacent switching devices are interconnected by series and / or parallel connection.

[0009] As one possible implementation, the series diode unit specifically includes: a second diode D2 and a third diode D3; the negative terminal of D2 is connected to S2, the positive terminal of D2 is connected to the negative terminal of D3, and the positive terminal of D3 is connected to S3; the second terminal of the first inductor in the resonant unit is connected between D2 and D3. Furthermore, the series diode unit in this embodiment can also be called a clamping unit, which can be used to prevent the voltage of the second access terminal S2 from changing.

[0010] The controller can set the ratio of the first voltage to the second voltage according to different scenarios. The flip-flop conversion circuit provided in this application embodiment can be applied to scenarios such as boost conversion, buck conversion, and polarity conversion. In the boost conversion scenario, the second voltage can be greater than the first voltage. In the buck conversion scenario, the second voltage can be less than the first voltage. In the polarity conversion scenario, the second voltage can be the opposite of the first voltage. In this application embodiment, the range of the second voltage can be determined based on the range of the first voltage provided by the input unit. Specifically, as one possible implementation, the controller is specifically configured to: when the ratio of the first voltage to the second voltage is set to a first target ratio, control the switching device in the second switching module to turn on, causing the first capacitor and the first inductor in the resonant unit to resonate, and the resonant unit to reverse charge the output capacitor in the output capacitor unit through D3 in the series diode unit; when the resonant current on the first inductor in the resonant unit is detected to be 0, control the switching device in the second switching module to turn off; control the switching device in the first switching module and the switching device in the energy storage switching unit to turn on; the first voltage charges the first inductor; control the switching device in the first switching module to turn on, causing the first capacitor and the first inductor in the resonant unit to resonate; when the resonant current on the first inductor in the resonant unit is detected to be 0, control the switching device in the first switching module to turn off.

[0011] In one possible implementation, when the ratio of the first voltage to the second voltage is set to a second target ratio, the controller controls the switching device in the second switching module to turn on, causing the first capacitor and the first inductor in the resonant unit to resonate; when the resonant current on the first inductor in the resonant unit is detected to be 0, the controller controls the switching device in the second switching module to turn off; the controller controls the switching device in the first switching module to turn on, causing the first capacitor and the first inductor in the resonant unit to resonate; when the resonant current on the first inductor in the resonant unit is detected to be 0, the controller controls the switching device in the first switching module to turn off.

[0012] There are many different connection methods for the half-bridge switching unit and the devices connected to the outside of the half-bridge switching unit. As one possible implementation, the flip-flop circuit also includes a second capacitor and a third capacitor. One end of the second capacitor is connected to S1, and the other end is connected to one end of the third capacitor. The other end of the third capacitor is connected to S2.

[0013] In one possible implementation, the first switching module includes: a first switching transistor Q1, a second switching transistor Q2, and a fourth diode D4; the second switching module includes: a third switching transistor Q3, a fourth switching transistor Q4, and a fifth diode D5; the first electrode of Q1 is connected to S1, the second electrode of Q1 is connected to the first electrode of Q2, the second electrode of Q1 is connected to the first terminal of the first capacitor, and the negative terminal of D4 is connected to the second electrode of Q1; the first electrode of Q3 is connected to the first terminal of the first capacitor, the second electrode of Q3 is connected to the first electrode of Q4, the second electrode of Q4 is connected to S2, the positive terminal of D5 is connected to the second electrode of Q3; and the positive terminal of D4 is connected to the negative terminal of D5.

[0014] As one possible implementation, the switching circuit further includes a fourth capacitor and a fifth capacitor. One end of the fourth capacitor is connected to S1, and the other end is connected to one end of the fifth capacitor. The other end of the fifth capacitor is connected to S2, and the other end of the fourth capacitor is also connected to the positive terminal of D4.

[0015] In one possible implementation, the controller is further configured to: control Q3 and Q4 in the second switching module to conduct when the ratio of the first voltage to the second voltage is set to a first target ratio, so that the first capacitor and the first inductor in the resonant unit resonate, and the resonant unit reverse-charges the output capacitor in the output capacitor unit through D3 in the series diode unit; control Q3 and Q4 in the second switching module to disconnect when the resonant current on the first inductor in the resonant unit is detected to be 0; control Q1 and Q2 in the first switching module to conduct and the switching device in the energy storage switching unit to conduct; charge the first inductor with the first voltage; control Q1 and Q2 in the first switching module to conduct, so that the first capacitor and the first inductor in the resonant unit resonate; control Q1 and Q2 in the first switching module to disconnect when the resonant current on the first inductor in the resonant unit is detected to be 0; control Q3 in the first switching module to conduct, and the inductor current on the first inductor in the resonant unit reverse-charges the output capacitor in the output capacitor unit through Q3, D5, and D3.

[0016] In one possible implementation, the controller is further configured to: control Q3 in the second switching module to turn on when the ratio of the first voltage to the second voltage is set to a second target ratio, so that the inductor current on the first inductor in the resonant unit reverse charges the output capacitor in the output capacitor unit through Q3, D5, and D3; control Q3 and Q4 in the first switching module to turn on, so that the first capacitor and the first inductor in the resonant unit resonate; control Q3 and Q4 in the second switching module to turn off when the resonant current on the first inductor in the resonant unit is detected to be 0; control Q2 in the second switching module to turn on, so that the inductor current on the first inductor in the resonant unit reverse charges the output capacitor in the output capacitor unit through Q2, D4, and D3; control Q1 and Q2 in the first switching module to turn on, so that the first capacitor and the first inductor in the resonant unit resonate; and control Q1 and Q2 in the first switching module to turn off when the resonant current on the first inductor in the resonant unit is detected to be 0.

[0017] In one possible implementation, the controller is further configured to: control Q3 in the second switching module to turn on when the ratio of the first voltage to the second voltage is set to a third target ratio; control Q3 in the second switching module to turn off when the resonant current on the first inductor in the resonant unit is 0; control Q1 and Q2 in the first switching module to turn on and the switching devices in the energy storage switching unit to turn on; charge the first inductor with the first voltage; control Q1 and Q2 in the first switching module to turn on and the switching devices in the energy storage switching unit to turn off; cause the first capacitor and the first inductor in the resonant unit to resonate; and control Q3 in the second switching module to turn on.

[0018] In one possible implementation, the energy storage switching unit includes a sixth capacitor connected in parallel with a first diode D1, the sixth capacitor being used to eliminate voltage spikes in at least one switching device in the energy storage switching unit.

[0019] In one implementation, the input unit specifically includes: an input DC source and a DC boost circuit; the DC boost circuit is used to boost the first voltage of the input DC source.

[0020] Secondly, this application provides a photovoltaic power generation system, including the switching conversion circuit provided in the first aspect, multiple photovoltaic strings, and an inverter circuit; the multiple photovoltaic strings are connected to the input unit of the switching conversion circuit; the output unit of the switching conversion circuit is connected to the inverter circuit; the switching conversion circuit is used to convert the first voltage output by the multiple photovoltaic strings into a second voltage, and output the second voltage at the output unit; the output terminal of the inverter circuit is connected to the power grid to convert the second voltage into AC voltage and provide it to the power grid.

[0021] These or other aspects of this application will become more apparent from the description of the following embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an existing photovoltaic power generation system structure;

[0023] Figure 2 This is a schematic diagram of the current DC-DC and RSCC circuit topologies;

[0024] Figure 3 This is a schematic diagram of a flip-converter circuit.

[0025] Figure 4 This is a schematic diagram of the structure of a half-bridge switching unit;

[0026] Figure 5 This is a schematic diagram of the specific structure of a half-bridge switching unit;

[0027] Figure 6 This is a schematic diagram of the structure of a series diode unit;

[0028] Figures 7A-7C Schematic diagram of the on / off state of the flip-conversion circuit Figure 1 ;

[0029] Figure 7D Timing of the flip-converter circuit Figure 1 ;

[0030] Figures 8A-8B Schematic diagram of the on / off state of the flip-conversion circuit Figure 2 ;

[0031] Figure 8C Timing of the flip-converter circuit Figure 2 ;

[0032] Figure 9 This is a schematic diagram of the flip-conversion circuit corresponding to structure one;

[0033] Figure 10 This is a schematic diagram of the flip-conversion circuit corresponding to structure two;

[0034] Figure 11 This is a schematic diagram of the flip-conversion circuit corresponding to structure three;

[0035] Figure 12A This is a schematic diagram of the flip-conversion circuit corresponding to structure four;

[0036] Figure 12B This is a schematic diagram of structure five corresponding to the flip-conversion circuit;

[0037] Figure 13A This is a schematic diagram of structure six corresponding to the flip-conversion circuit;

[0038] Figure 13BThis is a schematic diagram of the flip-conversion circuit corresponding to structure seven;

[0039] Figure 14A This is a schematic diagram of structure eight corresponding to the flip-conversion circuit;

[0040] Figure 14B This is a schematic diagram of structure nine corresponding to the flip-conversion circuit;

[0041] Figure 15A This is a schematic diagram of the corresponding structure ten of the flip-conversion circuit;

[0042] Figure 15B This is a schematic diagram of structure eleven corresponding to the flip-conversion circuit;

[0043] Figure 16A This is a schematic diagram of structure twelve corresponding to the flip-conversion circuit;

[0044] Figure 16B This is a schematic diagram of structure thirteen corresponding to the flip-conversion circuit;

[0045] Figures 17A-17D On / off diagram of the flip-converter circuit Figure 3 ;

[0046] Figure 17E Timing of the flip-converter circuit Figure 3 ;

[0047] Figures 18A-18D Schematic diagram of the on / off state of the flip-conversion circuit Figure 4 ;

[0048] Figure 18E Timing of the flip-converter circuit Figure 4 ;

[0049] Figures 19A-19D Schematic diagram of the on / off state of the flip-conversion circuit Figure 5 ;

[0050] Figure 19E Timing of the flip-converter circuit Figure 5 ;

[0051] Figure 20 This is a schematic diagram of a photovoltaic power generation system. Detailed Implementation

[0052] DC converters are used in common high-voltage direct current transmission systems, uninterruptible power supply systems, and photovoltaic power generation systems to convert DC power into electrical energy. Figure 1 In a typical photovoltaic (PV) power generation system, the DC combiner box must consider the current carrying capacity and cable losses of the downstream cables. Therefore, the DC combiner box must reduce the output current while ensuring output power in order to reduce cable losses.

[0053] Current DC combiner boxes mainly include DC-DC converters and RSCC circuits. Among them, [the following is a list of components]. Figure 1 As an example, in Figure 1 The four photovoltaic modules in the upper half of the circuit are connected to the DC-DC circuit in the DC combiner box, and the DC-DC circuit is connected in parallel to output V. BUS+ and V BUS+ Input to the DC bus; Figure 1 The four photovoltaic modules in the lower half of the circuit are also connected in parallel to the DC-DC circuit, and then connected to the resonant switched capacitor circuit RSCC circuit. The RSCC circuit outputs V. BUS- and V BUS- The output is connected to the DC bus, at the BUSN point (i.e., the zero voltage potential point), V BUS+ With V BUS- After being connected in series, the total output voltage to the subsequent inverter can be twice V. BUS Voltage. Existing technology uses the above method to increase the voltage on the DC bus while maintaining the same output power, thereby reducing the output current.

[0054] The excessive use of semiconductor devices in the DC-DC and RSCC circuit topology increases the overall manufacturing cost of the DC combiner box. Consequently, the large number of semiconductors also leads to higher overall losses in the DC combiner box, ultimately resulting in relatively low conversion efficiency for both the DC combiner box and the entire photovoltaic power generation system.

[0055] In view of this, this application provides a switching converter circuit, which, compared with the topology composed of DC-DC circuits and RSCC circuits in the prior art, can significantly reduce the number of semiconductor devices in the DC combiner box, thereby improving conversion efficiency while reducing costs.

[0056] See Figure 3 As shown, the flip-flop converter circuit 300 provided in this application embodiment may include: a first access terminal S1, a second access terminal S2, a third access terminal S3, a half-bridge switching unit 3011, an output capacitor unit 3012, a resonant unit 3013, a series diode unit 3014, an energy storage switching unit 302, an input unit 303, an output unit 304, and a controller 305, wherein the half-bridge switching unit 3011 includes N switching devices, where N is an even number;

[0057] The controller 305 can be connected to the half-bridge switching unit 3011 and the energy storage switching unit 302 to control the switching devices in the switching unit 3011 and the energy storage switching unit 302.

[0058] In this embodiment of the application, the positive input terminal 303a of the input unit 303 is connected to the first access terminal S1, and the negative input terminal 303b of the input unit 303 is connected to the second access terminal S2.

[0059] The first terminal 3012a of the output capacitor unit 3012 is connected to the second access terminal S2, and the second terminal 3012b of the output capacitor unit 3012 is connected to the third access terminal S3; the first terminal 3011a of the half-bridge switch unit 3011 is connected to the first access terminal S1, the second terminal 3011b of the half-bridge switch unit 3011 is connected to the second access terminal S2, the third terminal 3011c of the half-bridge switch unit 3011 is connected to the controller 305, and the fourth terminal 3011d of the half-bridge switch unit 3011 is connected to the first terminal 3013a of the resonant unit 3013; the first terminal 3014a of the series diode unit 3014 is connected to the second access terminal S2, the second terminal 3014b of the series diode unit 3014 is connected to the third access terminal S3, and the third terminal 3014c of the series diode unit 3014 is connected to the second terminal 3013b of the resonant unit 3013.

[0060] The first terminal 302a of the energy storage switch unit 302 is connected between the second terminal 3011b of the half-bridge switch unit 3011 and the first terminal 3014a of the series diode unit 3014. The second terminal 302b of the energy storage switch unit 302 is connected to the third terminal 3013c of the resonant unit. The third terminal 302c of the energy storage switch unit 302 is connected to the controller 305.

[0061] The positive output terminal 304a of the output unit 304 is connected to the first access terminal S1, and the negative output terminal 304b of the output unit 304 is connected to the third access terminal S3.

[0062] Specifically, the input unit 303 in this embodiment may also include at least one capacitor to stabilize the first voltage and store electrical energy.

[0063] In this embodiment, the resonant inductor and resonant capacitor in the resonant unit 3013 can be connected in series. The resonant unit 3013 may include a first capacitor and a first inductor connected in series. The first end of the first inductor is connected to the half-bridge switching unit 3011, and the second end of the first capacitor is connected to the series diode unit 3014; the second end of the first inductor is connected to the first end of the first capacitor.

[0064] In this embodiment, the first inductor and the first capacitor in the resonant unit 3013 are used to transfer energy and enable the switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302 to operate in a soft-switching state. Alternatively, the resonant unit 3013 can act as an energy transfer unit (energy relay component or energy relay module). In other words, the resonant unit 3013 can act as an energy transfer medium, first receiving the first voltage from the input unit 303 for charging, and then providing electrical energy to the output capacitor unit 3012 to charge the output capacitor unit 3012. Finally, the output unit 304 receives the electrical energy jointly output by the input unit 303 and the output capacitor unit 3012, thereby realizing the conversion of the input first voltage into a higher voltage for output.

[0065] The switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302 in this application embodiment can be one or more of various types of switching devices, such as metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), field effect transistors (FETs), silicon carbide (SiC) or gallium nitride (GaN) power transistors. These will not be listed individually in this application embodiment. Each switching device can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the switching on or off. When the switch is on, current can be transferred between the first electrode and the second electrode; when the switch is off, current cannot be transferred between the first electrode and the second electrode. Taking a MOSFET as an example, the control electrode of the switch is the gate, the first electrode of the switch can be the source of the switching device, and the second electrode can be the drain of the switching device; alternatively, the first electrode can be the drain of the switch, and the second electrode can be the source of the switch. The first end of the main power transistor and the first end of the auxiliary power transistor can be either the source or the drain. When the first end is the source, the second end is the drain, and when the first end is the drain, the second end is the source.

[0066] The number of switching devices in the aforementioned half-bridge switching unit 3011 and energy storage switching unit 302 can be related to the magnitude of the first voltage and the withstand voltage capability of the switching devices. When specifically designing the number of switching devices in the half-bridge switching unit 3011 and energy storage switching unit 302, if the first voltage is large and the withstand voltage capability of the switching devices is low, multiple switching devices can be connected in series to divide the first voltage, thereby ensuring that the switching devices with low withstand voltage capability can work normally.

[0067] The output capacitor unit 3012 provided in this embodiment is connected in parallel across the series diode unit 3014. The series diode unit 3014 includes multiple diodes connected in series, with the anode of each diode connected to the cathode of the adjacent diode. The first diode is connected to S2, and the last diode is connected to S3. The output capacitor unit 3012 may include at least one capacitor. It should be understood that the series diode unit 3014 can also be composed of other components to achieve the function or role of the series diode unit 3014 in this embodiment. This embodiment does not impose excessive limitations on this aspect.

[0068] The controller 305 provided in this application embodiment is used to control the turn-off of the switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302, convert the first voltage input by the input unit 303 into a second voltage, and output the second voltage in the output unit 304.

[0069] Optionally, the controller 305 in the embodiments of the application may be a general-purpose central processing unit (CPU), a general-purpose processor, a digital signal processing unit (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The aforementioned processor may also be a combination that implements computing functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0070] For example, when the controller 305 controls the half-bridge switching unit 3011 to transmit the first voltage provided by the input unit 303 to the series diode unit 3014, it also controls the half-bridge switching unit 3011 to transmit the electrical energy provided by the input unit 303 to the resonant unit 3013, thus enabling the input unit 303 to charge the resonant unit 3013. Then, the energy storage switching unit 302 performs voltage conversion processing on the first voltage provided by the input unit 303, and then controls the half-bridge switching unit 3011 to transmit the electrical energy in the resonant unit 3013 to the output capacitor unit 3012, ultimately enabling the resonant unit 3013 to charge the output capacitor unit 3012, and the output unit 304 outputs the second voltage.

[0071] In this embodiment, the controller 305 can control the half-bridge switching unit 3011 to transfer the electrical energy provided by the input unit 303 to the output capacitor unit 3012, thereby enabling the input unit 303 to charge the output capacitor unit 3012. The controller 305 can also send control signals or drive signals to the half-bridge switching unit 301. After receiving the control signal or drive signal, the half-bridge switching unit 301 transfers the electrical energy provided by the input unit 303 to the output capacitor unit 3012. Alternatively, the half-bridge switching unit 301 may not transfer the electrical energy provided by the input unit 303 to the output capacitor unit 3012 if it does not receive the control signal or drive signal.

[0072] Furthermore, to prevent excessive current in the circuit during charging from affecting the performance of the switches in the half-bridge switching unit 3011, the controller 305 can also control the duration for which the half-bridge switching unit 3011 transfers the electrical energy provided by the input unit 303 to the output capacitor unit 3012. For example, the controller 305 continuously sends control signals or drive signals to the half-bridge switching unit 3011 for a preset duration. The half-bridge switching unit 3011 continuously transfers the electrical energy provided by the input unit 303 to the output capacitor unit 3012 for the preset duration. The preset duration can be less than one control cycle.

[0073] The voltage increase of output capacitor unit 3012 varies depending on the charging duration. That is, the voltage increase across output capacitor unit 3012 differs depending on the duration for which controller 305 sends control or drive signals to half-bridge switching unit 3011. For example, controller 305 may continuously send control or drive signals to half-bridge switching unit 3011 for a first set duration. Controller 305 may also continuously send control or drive signals to half-bridge switching unit 3011 for a second set duration. If the first and second set durations are different values, the voltage increase of output capacitor unit 3012 after charging for the first set duration will differ from the voltage increase after charging for the second set duration.

[0074] The output capacitor unit 3012 provided in this embodiment can be charged multiple times. The controller 305 can control the half-bridge switching unit 3011 to transfer electrical energy from the resonant unit 3013 to the output capacitor unit 3013 multiple times. After the resonant unit 3013 is recharged, the controller 305 can control the half-bridge switching unit 3011 to transfer electrical energy from the resonant unit 3013 to the output capacitor unit 3012. The charging duration of the output capacitor unit 3012 each time can be the same or different.

[0075] The controller 305 can also set the ratio of the first voltage to the second voltage according to different scenarios. The flip-conversion circuit provided in this application embodiment can be applied to scenarios such as boost conversion, buck conversion, and polarity conversion. In the boost conversion scenario, the second voltage can be greater than the first voltage. In the buck conversion scenario, the second voltage can be less than the first voltage. In the polarity conversion scenario, the second voltage can be the opposite of the first voltage. In this application embodiment, the range of the second voltage can be determined according to the range of the first voltage provided by the input unit 303. The flip-conversion circuit 300 provided in this application embodiment can also be applied to other voltage conversion scenarios, which will not be elaborated here.

[0076] See Figure 4 As shown, in one possible implementation, the half-bridge switching unit 3011 may include: a first switching module 3015 and a second switching module 3016; the first switching module 3015 includes at least one switching device, and the second switching module 3016 includes at least one switching device. One end of the first switching module 3015 is connected to S1, and the other end is connected to one end of the second switching module 3016. The first end 3013a of the resonant unit 3013 is connected between the first switching module 3015 and the second switching module 3016.

[0077] See Figure 5As shown, the first switch module 3015 and the second switch module 3016 each include a switching device. The first electrode of the switching device in the first switch module 3015 is connected to S1, the second electrode of the switching device in the first switch module 3015 is connected to the first electrode of the switching device in the second switch module 3016, and the second electrode of the switching device in the second switch module 3016 is connected to S2. One end of the first inductor is connected to the second electrode of the switching device in the first switch module 3015.

[0078] In one possible implementation, the first switch module 3015 and the second switch module 3016 each include a plurality of switching devices. The switching devices in the first switch module 3015 and the second switch module 3016 can be connected in series, in parallel, or in a combination of series and parallel connections. No further limitations are imposed here, and those skilled in the art should know this.

[0079] The series diode unit 3014 in this embodiment can also be called a clamping unit, which can be used to prevent the voltage of the second access terminal S2 from changing. See also... Figure 6 As shown, in one possible implementation, the series diode unit 3014 includes: a second diode D2 and a third diode D3; the negative terminal of D2 is connected to S2, the positive terminal of D2 is connected to the negative terminal of D3, and the positive terminal of D3 is connected to S3; the second terminal of the first inductor in the resonant unit 3013 is connected between D2 and D3.

[0080] When the output unit 304 in this embodiment requires a higher second voltage, based on the architecture of the above embodiment, the controller 305 can control the switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302 to convert the first voltage input by the input unit 303 into the second voltage, so that the ratio of the first voltage to the second voltage is the first target ratio.

[0081] Figures 7A-7C The diagram shows the open and closed circuit states in the switching converter circuit 300. The controller 305 can be used to control the switching converter circuit to work in different states. t0 to t4 represent different states of the switching converter circuit 300 under different timing sequences. The solid black line represents the open circuit state in the switching converter circuit 300, and the dashed line represents the closed circuit state in the switching converter circuit 300.

[0082] See Figure 7A As shown, during the t0 to t1 stage: the controller 305 can control the switching device in the second switching module 3016 to conduct, thereby forming a path between the second access terminal S2, the second switching module 3016, the resonant unit 3013, D3, and the third access terminal S3. This causes the first capacitor and the first inductor in the resonant unit 3013 to resonate, and the resonant unit 3013 reverse-charges the output capacitor in the output capacitor unit 3012 through the D3 in the series diode unit 3014. The voltage increase across the output capacitor in the output capacitor unit 3012 varies depending on the conduction duration of the switching device in the second switching module 3016. The specific conduction duration can be determined based on the ratio between the first voltage and the second voltage; the larger the second voltage, the longer the conduction duration of the switching device in the second switching module 3016.

[0083] During the t1 to t2 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the switching device in the second switching module to open.

[0084] See Figure 7B As shown, during the t2 to t3 stage: the controller 305 can control the switching devices in the first switching module 3015 and the switching devices in the energy storage switching unit to be turned on; so that the first access terminal S1, the first switching module 3015, the resonant unit 3013, the energy storage switching unit 302 and the second access terminal S2 form a path, and the first voltage charges the first inductor.

[0085] See Figure 7C As shown, during the t3 to t4 stage: the controller 305 can control the switching device in the first switching module 3015 to be turned on, so that the first access terminal S1, the first switching module 3015, the resonant unit 3013, D2 and the second access terminal S2 form a path, so that the first capacitor and the first inductor in the resonant unit 3013 resonate.

[0086] During the t4 to t0 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the switching device in the first switching module to turn off. It should be noted that the controller 305 can control the switching circuit 300 to operate in different states in a cyclical execution mode of "t0 to t1 phase - t1 to t2 phase...". The specific starting state of the cycle is not specifically limited; it can use either the t0 to t1 phase or the t1 to t2 phase as the starting state. The controller 305 can also control the duration of each phase. For example, by controlling the duration of the high-level pulse or the duration of the low-level pulse, the conduction duration of the switching device in the first switching module 3015 during the t0 to t1 phase can be controlled.

[0087] See Figure 7D The figure shows the state timing diagram of some switching devices and power devices in the flip-converter circuit 300.

[0088] The controller 305 executes the above steps in a loop, thereby boosting and flipping the first voltage input by the input unit 303 and outputting it together with the first voltage to obtain the second voltage, which is then output by the output unit 304.

[0089] In some scenarios, the back-end circuit does not require an excessively large voltage input; the second voltage is obtained solely from the combined output of the first voltage and the flipped first voltage, where the second voltage is twice the first voltage. Optionally, as a possible implementation, when the ratio of the first voltage to the second voltage is set to a second target ratio, Figures 8A-8B The diagram shows the open and closed circuit states in the switching converter circuit 300. The controller 305 can be used to control the switching converter circuit to work in different states. t0 to t3 represent different states of the switching converter circuit 300 under different timing sequences. The solid black line represents the open circuit state in the switching converter circuit 300, and the dashed line represents the closed circuit state in the switching converter circuit 300.

[0090] See Figure 8A As shown, during the t0 to t1 stage: the controller 305 can control the switching device in the second switching module 3016 to turn on, so that the first capacitor and the first inductor in the resonant unit 3013 resonate.

[0091] During the t1 to t2 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the switching device in the second switching module 3016 to open.

[0092] See Figure 8BAs shown, during the t2 to t3 stage: the switching device in the first switching module 3015 is turned on, so that the first capacitor and the first inductor in the resonant unit 3013 resonate.

[0093] During the t3 to t0 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the switching device in the first switching module 3015 to open.

[0094] See Figure 8C The figure shows the state timing diagram of some switching devices and power devices in the flip-converter circuit 300.

[0095] The controller 305 executes the above steps in a loop, thereby flipping the first voltage input by the input unit 303 and outputting it together with the first voltage, so that the second voltage is output by the output unit 304.

[0096] The circuit structure provided by the embodiments of this application significantly reduces component costs, board space, and device losses compared to existing topologies. In addition, compared to the prior art, the structure provided by this application also significantly reduces the number of diodes, enabling the switching devices in the switching circuit 300 to have zero-voltage conduction conditions, thereby reducing switching losses.

[0097] As one possible implementation, the half-bridge switching unit 3011 and the devices externally connected to the half-bridge switching unit 3011 can have various different connection methods. The following embodiments illustrate various specific structures of the flip-flop converter circuit:

[0098] Structure 1: See Figure 9 As shown, based on the basic structure provided in the above embodiments, the flip-conversion circuit 300 may further include a second capacitor C2 and a third capacitor C3. One end of the second capacitor C2 is connected to S1, and the other end is connected to one end of the third capacitor C3. The other end of the third capacitor C3 is connected to S2. The second capacitor C2 and the third capacitor C3 can constitute an input capacitor unit, which can also store the electrical energy provided by the input unit 303.

[0099] Structure 2: See Figure 10As shown, the first switching module 3015 includes: a first switching transistor Q1, a second switching transistor Q2, and a fourth diode D4; the second switching module 3016 includes: a third switching transistor Q3, a fourth switching transistor Q4, and a fifth diode D5; the first electrode of Q1 is connected to S1, the second electrode of Q1 is connected to the first electrode of Q2, the second electrode of Q1 is connected to the first terminal of the first capacitor, and the negative terminal of D4 is connected to the second electrode of Q1; the first electrode of Q3 is connected to the first terminal of the first capacitor, the second electrode of Q3 is connected to the first electrode of Q4, the second electrode of Q4 is connected to S2, the positive terminal of D5 is connected to the second electrode of Q3; and the positive terminal of D4 is connected to the negative terminal of D5.

[0100] Structure 3: See Figure 11 As shown, based on structure two, the flip-conversion circuit 300 further includes: a fourth capacitor C4 and a fifth capacitor C5. One end of the fourth capacitor C4 is connected to S1, and the other end is connected to one end of the fifth capacitor C5. The other end of the fifth capacitor C5 is connected to S2, and the other end of the fourth capacitor C4 is also connected to the positive terminal of D4.

[0101] In addition, the component structure of the half-bridge switching unit 3011 can also have various variations of the following types, all of which can achieve voltage switching function:

[0102] Structure 4: See also Figure 12A As shown, the first switching module 3015 in the switching circuit 300 includes: a fifth switching transistor Q5, a sixth switching transistor Q6, and a fourth diode D6; the first electrode of Q5 is connected to S1, the second electrode of Q5 is connected to the first electrode of Q6, and the second electrode of Q6 is connected to the first terminal of the first inductor; the negative terminal of D6 is connected to the second electrode of Q5, and the positive terminal of D6 is connected to S1.

[0103] Structure 5: Based on Structure 4, see [link / reference] Figure 12B As shown, the flip-conversion circuit 300 further includes a sixth capacitor C6, which is connected between the positive terminal of D6 and S1.

[0104] Structure Six: See Figure 13A As shown, the first electrode of Q5 is connected to S1, the second electrode of Q5 is connected to the first electrode of Q6, and the second electrode of Q6 is connected to the first terminal of the first inductor; the negative terminal of D6 is connected to the second electrode of Q5, and the positive terminal of D6 is connected to S2.

[0105] Structure 7: Based on Structure 6, see [link / reference] Figure 13BAs shown, the seventh capacitor C7 is connected between the positive terminal of D6 and S2.

[0106] Structure 8: See Figure 14A As shown, the second switching module 3016 includes: a third switching transistor Q7, a fourth switching transistor Q8, and a seventh diode D7; the first electrode of Q7 is connected to the first end of the first inductor, the second electrode of Q7 is connected to the first electrode of Q8, and the second electrode of Q8 is connected to S2; the positive terminal of D7 is connected to the second electrode of Q7, and the negative terminal of D7 is connected to S1.

[0107] Structure Nine: Based on Structure Eight, see [link / reference] Figure 14B As shown, the flip-conversion circuit 300 further includes an eighth capacitor C8, which is connected to the negative terminal of D7 and S1.

[0108] Structure 10: See Figure 15A As shown, the first electrode of Q7 is connected to the first end of the first inductor, the second electrode of Q7 is connected to the first electrode of Q8, and the second electrode of Q8 is connected to S2; the positive electrode of D7 is connected to the second electrode of Q7, and the negative electrode of D7 is connected to S2.

[0109] Structure 11: Based on Structure 10, see reference. Figure 15B As shown, the ninth capacitor C9 is connected to the negative terminal of D7 and S2.

[0110] Structure Twelve: Based on Structure Two, see [link / reference] Figure 16A As shown, the positive electrode of D4 is also connected to S1.

[0111] Structure Thirteen: Based on Structure Two, see [link / reference] Figure 16B As shown, the positive electrode of D4 is also connected to S2.

[0112] It should be noted that the flip-conversion circuit 300 is not limited to the structures defined in structures one to thirteen above. All components in the flip-conversion circuit 300 can be combined in series or parallel, as long as the functions of the above components are consistent with those in the embodiments of this application after combination. No further limitations are imposed here.

[0113] Based on the architecture of the above embodiments, the controller 305 can convert the first voltage input by the input unit 303 into a second voltage by controlling the switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302, so that the ratio of the first voltage to the second voltage is a first target ratio.

[0114] This section uses structure three as an example to introduce the specific method of controlling the 305 flip-conversion circuit of the controller. Figures 17A-17D The diagram shows the open and closed circuit states of the switching converter 300. t0 to t5 represent different states of the switching converter 300 under different timing sequences. The solid black line represents the open circuit state of the switching converter 300, and the dashed line represents the closed circuit state of the switching converter 300.

[0115] See Figure 17A As shown, during the t0 to t1 stage: the controller 305 can control the Q3 and Q4 in the second switch module 3016 to be turned on, so that the first capacitor C1 and the first inductor in the resonant unit 3013 resonate, and the resonant unit 3013 reverse charges the output capacitor in the output capacitor unit 3012 through the D3 in the series diode unit 3014.

[0116] During the t1 to t2 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls Q3 and Q4 in the second switching module 3016 to disconnect.

[0117] See Figure 17B As shown, during the t2 to t3 stage: the controller 305 can control the Q1 and Q2 in the first switch module 3015 to be turned on and the switching device in the energy storage switch unit 302 to be turned on; thereby enabling the first voltage to charge the first inductor;

[0118] See Figure 17C As shown, during the t3 to t4 stage: the controller 305 can control the Q1 and Q2 in the first switch module to be turned on, so that the first capacitor and the first inductor in the resonant unit 3013 can resonate.

[0119] During the t4 to t5 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls Q1 and Q2 in the first switching module 3015 to disconnect.

[0120] See Figure 17D As shown, during the t5 to t0 stage: the controller 305 can control the Q3 in the first switch module 3015 to be turned on, and the inductor current on the first inductor in the resonant unit 3013 charges the output capacitor in the output capacitor unit 3012 in reverse through the Q3, the D5, and the D3.

[0121] See Figure 17EThe figure shows the state timing diagram of some of the switching devices and power devices in the above-mentioned switching circuit 300.

[0122] Specifically, during the operation of the switching circuit 300, energy is primarily stored in the capacitor of the output capacitor unit 3012 through the newly added energy storage switch unit 302. At this time, the inductor current rises linearly. When the switch in the energy storage switch unit 302 is turned off, the first inductor and the first capacitor in the resonant unit resonate, continuing to supply energy to the capacitor in the output capacitor unit 3012 until the inductor current drops to 0. When the switching devices Q3 and Q4 in the second switch module 3016 are turned on, the first inductor and the first capacitor resonate, causing the capacitor in the output capacitor unit 3012 to release energy until the inductor current drops to 0. By adjusting the duty cycle of the switching devices in the energy storage switch unit 302, the magnitude of the second voltage input to the output unit 304 can be adjusted.

[0123] Furthermore, under the switching converter circuit 300 and control scheme provided in this application, switching devices Q1 and Q2 can achieve soft switching, the switching devices in the energy storage switching unit 302 can achieve zero-current turn-on, diode D4 can achieve zero-current turn-off, switching devices Q3 and Q4 can achieve soft switching, and diode D5 can achieve zero-current turn-on. Therefore, the semiconductor losses in the switching converter circuit 300 provided in this application are relatively small. Moreover, the number of inductors is significantly reduced compared to existing technologies, and the inductance value only needs to be designed according to the resonance requirements. This reduces the overall circuit losses and cost, and significantly improves power density. Therefore, the circuit structure provided in this application can effectively improve the circuit's size, cost, and efficiency, while reducing circuit complexity.

[0124] In some scenarios, the back-end circuit does not require a large voltage input. The controller 305 controls the switching devices in the half-bridge switching unit 3011 and the energy storage switching unit 302 to only flip the first voltage, and finally obtains the second voltage by combining the first voltage and the flipped first voltage. Taking structure three as an example again, Figures 18A-18D The diagram shows the open and closed circuit states of the switching converter 300. t0 to t5 represent different states of the switching converter 300 under different timing sequences. The solid black line represents the open circuit state of the switching converter 300, and the dashed line represents the closed circuit state of the switching converter 300.

[0125] See Figure 18AAs shown, during the t0 to t1 stage: when the ratio of the first voltage to the second voltage is set to the second target ratio, the controller 305 controls the Q3 in the second switch module 3016 to be turned on, and the inductor current on the first inductor in the resonant unit 3013 can reverse charge the output capacitor in the output capacitor unit 3012 through Q3, D5, and D3.

[0126] See Figure 18B As shown, during the t1 to t2 stage: the controller 305 can control the Q3 and Q4 in the first switch module 3015 to be turned on, so that the first capacitor and the first inductor in the resonant unit 3013 can resonate.

[0127] During the t2 to t3 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls Q3 and Q4 in the second switching module 3016 to disconnect.

[0128] See Figure 18C As shown, during the t3 to t4 stage: the controller 305 can control the Q2 in the second switch module 3016 to be turned on, and the inductor current on the first inductor in the resonant unit 3013 charges the output capacitor in the output capacitor unit 3012 in reverse through Q2, D4, and D3;

[0129] See Figure 18D As shown, during the t4 to t5 stage: the controller 305 can control the Q1 and Q2 in the first switch module 3015 to be turned on, so that the first capacitor and the first inductor in the resonant unit 3013 can resonate.

[0130] During the t5 to t0 phase: When the controller 305 detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the Q1 and Q2 in the first switching module to disconnect.

[0131] See Figure 18E The figure shows the state timing diagram of some of the switching devices and power devices in the above-mentioned switching circuit 300.

[0132] In some scenarios, the ratio of the first voltage to the second voltage is set as a third target ratio. The upper limit of the third target ratio is higher than the first target ratio. Or, when the on-state voltage drop of the switching device in the flip-flop circuit 300 is large, the specific control method will be different. Taking structure three as an example, Figures 19A-19DThe diagram shows the open and closed circuit states of the switching converter 300. t0 to t5 represent different states of the switching converter 300 under different timing sequences. The solid black line represents the open circuit state of the switching converter 300, and the dashed line represents the closed circuit state of the switching converter 300.

[0133] See Figure 19A As shown, during the t0 to t1 stage: the controller 305 controls the Q3 in the second switch module 3016 to be turned on;

[0134] During the t1 to t2 phase: when the controller detects that the resonant current on the first inductor in the resonant unit 3013 is 0, it controls the Q3 in the second switch module 3016 to disconnect.

[0135] See Figure 19B As shown, during the t2 to t3 phase: the controller 305 controls the Q1 and Q2 in the first switch module 3015 to be turned on and the switching device in the energy storage switch unit 302 to be turned on; the first voltage charges the first inductor.

[0136] See Figure 19C As shown, during the t3 to t4 stage: the controller 305 controls the Q1 and Q2 in the first switch module 3015 to be turned on and the switching device in the energy storage switch unit 302 to be turned off; causing the first capacitor and the first inductor in the resonant unit 3013 to resonate.

[0137] See Figure 19D As shown, during the t4 to t0 stage: the controller 305 controls the Q3 in the second switch module 3016 to be turned on.

[0138] See Figure 19E The figure shows the state timing diagram of some of the switching devices and power devices in the above-mentioned switching circuit 300.

[0139] In order to reduce the turn-off voltage of the switching devices in the energy storage switch unit 302, as a possible implementation, the energy storage switch unit 302 further includes: a sixth capacitor, which is connected in parallel with the first diode D1, and the sixth capacitor is used to eliminate voltage spikes of the at least one switching device in the energy storage switch unit 302.

[0140] When the first voltage input to the input unit 303 is low, as one possible implementation, the input unit includes: an input DC source and a DC boost circuit;

[0141] The DC boost circuit is used to boost the first voltage of the input DC source.

[0142] It should be noted that the application scenarios provided in this application can be, but are not limited to, the photovoltaic power generation system described in the above embodiments. Any electrical energy application that requires DC-to-DC voltage conversion, such as high voltage direct current transmission (HVDC) systems and uninterruptible power supply (UPS) systems, can use the flip-conversion circuit 300 provided in this application for voltage conversion. No specific limitations are made here.

[0143] This application also provides a photovoltaic power generation system, see reference. Figure 20 As shown, the photovoltaic power generation system 400 includes the switching conversion circuit 300, multiple photovoltaic strings 401, and inverter circuit 402 described in the above embodiment; the multiple photovoltaic strings 401 are connected to the input unit 303 of the switching conversion circuit 300; the output unit 304 of the switching conversion circuit 300 is connected to the inverter circuit 402; the switching conversion circuit 300 is used to convert the first voltage output by the multiple photovoltaic strings 401 into a second voltage, and output the second voltage in the output unit 304; the output terminal of the inverter circuit 402 is connected to the power grid to convert the second voltage into AC voltage and provide it to the power grid.

[0144] The photovoltaic power generation system 400 provided in this application embodiment can be applied to large-scale photovoltaic power plant application scenarios, small and medium-sized distributed power plant application scenarios, and residential photovoltaic power generation system application scenarios. The photovoltaic power generation system 400 can convert light energy into direct current, and then convert the direct current into alternating current to provide alternating current to the load or the power grid. It can also be called a photovoltaic inverter system or a photovoltaic inverter system.

[0145] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0146] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0147] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0148] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0149] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A flip-conversion circuit, characterized in that, The switching circuit includes: a first access terminal S1, a second access terminal S2, a third access terminal S3, a half-bridge switching unit, an output capacitor unit, a resonant unit, a series diode unit, an energy storage switching unit, an input unit, an output unit, and a controller; the half-bridge switching unit includes N switching devices, where N is an even number; The half-bridge switch unit is connected between S1 and S2, the series diode unit is connected between S2 and S3, the output capacitor unit is connected in parallel across the series diode unit, the input unit is connected between S1 and S2, and the output unit is connected between S1 and S3. The energy storage switch unit includes at least one switching device and a first diode D1, wherein the at least one switching device is connected in series with the first diode D1; The resonant unit includes a first capacitor and a first inductor. The first end of the first inductor is connected to the half-bridge switching unit, and the second end of the first capacitor is connected to the series diode unit. The second end of the first inductor is connected to the first end of the first capacitor. One end of the energy storage switch unit is connected between the half-bridge switch unit and the series diode unit, and the other end is connected to the second end of the first inductor; The controller is used to: convert the first voltage input to the input unit into a second voltage by controlling the switching devices in the half-bridge switching unit and the energy storage switching unit to be turned on or off, so that the output unit outputs the second voltage.

2. The flip-conversion circuit according to claim 1, characterized in that, The half-bridge switching unit includes a first switching module and a second switching module; the first switching module and the second switching module each include a switching device.

3. The flip-conversion circuit according to claim 1, characterized in that, The half-bridge switching unit includes: a first switching module and a second switching module; the first switching module and the second switching module each include multiple switching devices; in the first switching module and the second switching module, each pair of adjacent switching devices are connected to each other in series and / or in parallel.

4. The flip-conversion circuit according to claim 2 or 3, characterized in that, The series diode unit includes: a second diode D2 and a third diode D3; The negative terminal of D2 is connected to S2, the positive terminal of D2 is connected to the negative terminal of D3, and the positive terminal of D3 is connected to S3; the second terminal of the first capacitor in the resonant unit is connected between D2 and D3.

5. The flip-conversion circuit according to claim 4, characterized in that, The controller is specifically used for: When the ratio of the first voltage to the second voltage is set to the first target ratio, the switching device in the second switching module is controlled to turn on, so that the first capacitor and the first inductor in the resonant unit resonate, and the resonant unit reverse charges the output capacitor in the output capacitor unit through the D3 in the series diode unit. When the resonant current on the first inductor in the resonant unit is detected to be 0, the switching device in the second switching module is controlled to open. The switching devices in the first switching module and the energy storage switching unit are turned on; the first voltage charges the first inductor. The switching device in the first switching module is turned on, so that the first capacitor and the first inductor in the resonant unit resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the switching device in the first switching module is controlled to open.

6. The flip-conversion circuit according to claim 4, characterized in that, The controller is specifically used for: When the ratio of the first voltage to the second voltage is set to the second target ratio, the switching device in the second switching module is controlled to turn on, so that the first capacitor and the first inductor in the resonant unit resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the switching device in the second switching module is controlled to open. The switching device in the first switching module is turned on, so that the first capacitor and the first inductor in the resonant unit resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the switching device in the first switching module is controlled to open.

7. The flip-conversion circuit according to any one of claims 1-3 or 5-6, characterized in that, The switching circuit further includes a second capacitor and a third capacitor. One end of the second capacitor is connected to S1, and the other end is connected to one end of the third capacitor. The other end of the third capacitor is connected to S2.

8. The flip-conversion circuit according to claim 4, characterized in that, The first switching module includes: a first switching transistor Q1, a second switching transistor Q2, and a fourth diode D4; the second switching module includes: a third switching transistor Q3, a fourth switching transistor Q4, and a fifth diode D5; The first electrode of Q1 is connected to S1, the second electrode of Q1 is connected to the first electrode of Q2, the second electrode of Q2 is connected to the first terminal of the first inductor, and the negative electrode of D4 is connected to the second electrode of Q1. The first electrode of Q3 is connected to the first terminal of the first inductor, the second electrode of Q3 is connected to the first electrode of Q4, the second electrode of Q4 is connected to S2, the positive terminal of D5 is connected to the second electrode of Q3, and the positive terminal of D4 is connected to the negative terminal of D5.

9. The flip-conversion circuit according to claim 8, characterized in that, The switching circuit further includes a fourth capacitor and a fifth capacitor. One end of the fourth capacitor is connected to S1, and the other end is connected to one end of the fifth capacitor. The other end of the fifth capacitor is connected to S2, and the other end of the fourth capacitor is also connected to the positive terminal of D4.

10. The flip-conversion circuit according to claim 9, characterized in that, The controller is also used for: When the ratio of the first voltage to the second voltage is set to the first target ratio, the Q3 and Q4 in the second switching module are controlled to be turned on, so that the first capacitor and the first inductor in the resonant unit resonate, and the resonant unit reverse charges the output capacitor in the output capacitor unit through the D3 in the series diode unit. When the resonant current on the first inductor in the resonant unit is detected to be 0, the Q3 and Q4 in the second switching module are controlled to disconnect. Controlling the conduction of Q1 and Q2 in the first switching module and the conduction of the switching device in the energy storage switching unit; The first voltage charges the first inductor; By controlling the Q1 and Q2 in the first switching module to be turned on, the first capacitor and the first inductor in the resonant unit resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the Q1 and Q2 in the first switching module are controlled to disconnect. When Q3 in the first switch module is turned on, the inductor current on the first inductor in the resonant unit reverse charges the output capacitor in the output capacitor unit through Q3, D5, and D3.

11. The flip-conversion circuit according to claim 9, characterized in that, The controller is also used for: When the ratio of the first voltage to the second voltage is set to the second target ratio, Q3 in the second switch module is turned on, and the inductor current on the first inductor in the resonant unit charges the output capacitor in the output capacitor unit in reverse through Q3, D5, and D3. By controlling the Q3 and Q4 in the first switching module to be turned on, the first capacitor and the first inductor in the resonant unit are made to resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the Q3 and Q4 in the second switching module are controlled to disconnect. When Q2 in the second switch module is turned on, the inductor current on the first inductor in the resonant unit charges the output capacitor in the output capacitor unit in reverse through Q2, D4, and D3. By controlling the Q1 and Q2 in the first switching module to be turned on, the first capacitor and the first inductor in the resonant unit resonate. When the resonant current on the first inductor in the resonant unit is detected to be 0, the Q1 and Q2 in the first switching module are controlled to disconnect.

12. The flip-conversion circuit according to claim 9, characterized in that, The controller is also used for: When the ratio of the first voltage to the second voltage is set to a third target ratio, Q3 in the second switching module is controlled to be turned on; When the resonant current on the first inductor in the resonant unit is controlled to be 0, Q3 in the second switching module is controlled to be disconnected. The first voltage charges the first inductor; Q1 and Q2 in the first switching module and the switching device in the energy storage switching unit are turned on. Controlling the conduction of Q1 and Q2 in the first switching module and the disconnection of the switching device in the energy storage switching unit; causing the first capacitor and the first inductor in the resonant unit to resonate; Turn on Q2 in the first switch module.

13. The flip-flop converter circuit according to any one of claims 1-3, 5-6, or 8-12, characterized in that, The energy storage switch unit further includes a sixth capacitor, which is connected in parallel with the first diode D1, and the sixth capacitor is used to eliminate voltage spikes of the at least one switching device in the energy storage switch unit.

14. The flip-flop converter circuit according to any one of claims 1-3, 5-6, or 8-12, characterized in that, The input unit specifically includes: an input DC source and a DC boost circuit; The DC boost circuit is used to boost the first voltage of the input DC source.

15. A photovoltaic power generation system, characterized in that, It includes at least one flip-converter circuit as described in any one of claims 1-14, a plurality of photovoltaic strings, and an inverter circuit; the plurality of photovoltaic strings are connected to the input unit of the flip-converter circuit; and the output unit of the flip-converter circuit is connected to the inverter circuit. The flip-conversion circuit is used to convert the first voltage output by the plurality of photovoltaic strings into a second voltage, and output the second voltage in the output unit; The output of the inverter circuit is connected to the power grid to convert the second voltage into AC voltage and supply it to the power grid.

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