Bidirectional current conversion circuit and photovoltaic energy storage converter

Abstract

The utility model discloses a bidirectional current conversion circuit and a photovoltaic energy storage converter, and belongs to the technical field of photovoltaic energy storage. The bidirectional current conversion circuit comprises a main circuit and a bypass circuit, the main circuit is a bidirectional BUCK-BOOST circuit, the main circuit is provided with a first end and a second end, a first interface and a second interface of the first end are electrically connected with the battery respectively, and a third interface and a fourth interface of the second end are electrically connected with a bus of the inverter circuit respectively; the two ends of the bypass circuit are electrically connected with the first interface and the third interface respectively, the impedance of the bypass circuit is smaller than that of the main circuit, and the bypass circuit is used for conducting the first interface and the third interface when the voltage of the first end is larger than a preset voltage value. When the voltage of the first end is greater than the preset voltage, the main circuit is not in a boost working mode, the bypass circuit conducts the first interface and the third interface, and the impedance between the first interface and the third interface is reduced, so that the loss of the bidirectional current conversion circuit is reduced, and the working efficiency is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of photovoltaic energy storage, and in particular to a bidirectional current conversion circuit and a photovoltaic energy storage converter. Background Art

[0002] As a renewable and clean energy source, photovoltaic power generation systems have been widely used. Among them, photovoltaic energy storage inverters are the core equipment that enables the bidirectional flow of electrical energy between energy storage systems and the power grid. As a key component of photovoltaic power generation and energy storage systems, photovoltaic energy storage inverters play a vital role.

[0003] In related technologies, the internal circuit of a photovoltaic energy storage inverter has a bidirectional BUCK-BOOST (buck-boost) circuit. The two ends of the bidirectional BUCK-BOOST circuit are the battery and the inverter circuit bus. When the battery is in discharge mode, if the battery voltage is lower than the preset voltage, the bidirectional BUCK-BOOST circuit operates in boost mode to ensure that the voltage of the inverter circuit bus is higher than the battery voltage; if the battery voltage is higher than the preset voltage, the bidirectional BUCK-BOOST circuit stops the boost mode, and the battery current flows directly through the inductor and the body diode of the switch tube and then flows to the inverter circuit bus.

[0004] When the battery voltage of the above circuit is greater than the preset voltage, the body diode impedance of the inductor and the switch tube is relatively large, which leads to high circuit loss and low working efficiency. Utility Model Content

[0005] The embodiments of the present disclosure provide a bidirectional current conversion circuit and a photovoltaic energy storage converter that can solve the above-mentioned technical problems existing in the related art. The technical solution is as follows:

[0006] In a first aspect, there is provided a bidirectional current conversion circuit comprising a main circuit, a bypass circuit and a controller;

[0007] The main circuit is a bidirectional buck-boost circuit having a first end and a second end, wherein the first interface and the second interface of the first end are electrically connected to the battery respectively, and the third interface and the fourth interface of the second end are electrically connected to the inverter circuit bus respectively;

[0008] The two ends of the bypass circuit are electrically connected to the first interface and the third interface respectively. The impedance of the bypass circuit is smaller than the impedance of the main circuit. The bypass circuit is used to connect the first interface and the third interface when the voltage at the first end is greater than a preset voltage value.

[0009] In some possible embodiments, the main circuit includes a first capacitor, a second capacitor, a first inductor, a first switching tube, and a second switching tube. The first capacitor is electrically connected to the first interface and the second interface, respectively, the second capacitor is electrically connected to the third interface and the fourth interface, respectively, the first end of the first inductor is electrically connected to the first end of the first capacitor, the two ends of the first switching tube are electrically connected to the second end of the first inductor and the first end of the second capacitor, respectively, the first end of the second switching tube is electrically connected to the second end of the first inductor, and the second end of the second switching tube is electrically connected to the second end of the first capacitor and the second end of the second capacitor.

[0010] In some possible embodiments, the main circuit further includes a second inductor, a third switching tube, and a fourth switching tube. The first end of the second inductor is electrically connected to the first end of the first capacitor, the two ends of the third switching tube are electrically connected to the second end of the second inductor and the first end of the second capacitor, respectively, the first end of the fourth switching tube is electrically connected to the second end of the second inductor, and the second end of the fourth switching tube is electrically connected to the second end of the first capacitor and the second end of the second capacitor.

[0011] In some possible implementations, the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are each any one of an IGBT tube or a MOSFET tube.

[0012] In some possible implementations, the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube all have a body diode.

[0013] In some possible implementations, the bypass circuit includes a diode, an anode of the diode is electrically connected to the first interface, and a cathode of the diode is electrically connected to the third interface.

[0014] In some possible implementations, the bypass circuit includes a fifth switch tube and a controller, wherein two ends of the fifth switch tube are electrically connected to the first interface and the third interface respectively, and the conduction direction of the fifth switch tube is such that the current flows from the first interface to the third interface;

[0015] The controller is electrically connected to the first end, the second end, and the fifth switch tube. The controller is used to control the fifth switch tube to be turned on when the voltage of the first end is greater than a preset voltage value.

[0016] In some possible implementations, the bypass circuit includes a diode, a fifth switch tube, and a controller;

[0017] The anode of the diode is electrically connected to the first interface, and the cathode of the diode is electrically connected to the third interface;

[0018] The fifth switch tube and the diode are arranged in parallel, and the conduction direction of the fifth switch tube is that the first interface flows to the third interface;

[0019] The controller is electrically connected to the first end, the second end, and the fifth switch tube. The controller is used to control the fifth switch tube to be turned on when the voltage of the first end is greater than a preset voltage value.

[0020] In some possible implementations, the fifth switch tube has a body diode, and a conduction direction of the body diode is from the first interface to the third interface.

[0021] In a second aspect, a photovoltaic energy storage converter is provided, wherein the photovoltaic energy storage converter comprises the bidirectional current conversion circuit described in any one of the first aspects.

[0022] The beneficial effects of the technical solution provided by the present disclosure include at least:

[0023] In the present disclosure, when the voltage at the first end is greater than the preset voltage, the main circuit is not in the boost working mode, the bypass circuit connects the first interface and the third interface, and the impedance between the first interface and the third interface is reduced, thereby reducing the loss of the bidirectional current conversion circuit and improving working efficiency.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 This is one of the circuit schematic diagrams of a bidirectional current conversion circuit provided by an embodiment of the present disclosure.

[0027] Figure 2 This is the second circuit schematic diagram of a bidirectional current conversion circuit provided by an embodiment of the present disclosure.

[0028] Figure 3 This is the third circuit schematic diagram of a bidirectional current conversion circuit provided in an embodiment of the present disclosure.

[0029] Figure 4It is a circuit diagram of the internal circuit of the photovoltaic energy storage converter in the related art.

[0030] Figure 5 This is one of the current flow diagrams of a bidirectional current conversion circuit provided in an embodiment of the present disclosure.

[0031] Figure 6 This is the second current flow diagram of a bidirectional current conversion circuit provided in an embodiment of the present disclosure.

[0032] Reference numerals:

[0033] 1. Main circuit, 10. First end, 10a. First interface, 10b. Second interface, 20. Second end, 20a. Third interface, 20b. Fourth interface;

[0034] 11. First capacitor, 12. Second capacitor, 13. First inductor, 14. First switch, 15. Second switch, 16. Second inductor, 17. Third switch, 18. Fourth switch;

[0035] 2. Bypass circuit;

[0036] 21. Diode, 22. Fifth switch tube, 22a. Body diode, 23. Controller.

[0037] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0039] As a renewable and clean energy source, photovoltaic power generation systems have been widely used. Among them, photovoltaic energy storage inverters are the core equipment that enables the bidirectional flow of electrical energy between energy storage systems and the power grid. As a key component of photovoltaic power generation and energy storage systems, photovoltaic energy storage inverters play a vital role.

[0040] In the related art, refer to Figure 4 As shown, the internal circuit of the photovoltaic energy storage converter has a bidirectional buck-boost (buck-boost) circuit, which includes a first capacitor 11, a second capacitor 12, a first inductor 13, a first switch 14, and a second switch 15. The first end 10 of the bidirectional buck-boost circuit is used to be electrically connected to the battery, and the second end 20 of the bidirectional buck-boost circuit is used to be electrically connected to the inverter circuit bus.

[0041] When the battery is in discharge mode, if the battery voltage is less than a preset voltage, the bidirectional buck-boost circuit operates in boost mode to ensure that the voltage of the inverter circuit bus is higher than the battery voltage. If the battery voltage is greater than the preset voltage, the bidirectional buck-boost circuit stops the boost mode, and the battery current flows directly through the first inductor 13 and the body diode 22a of the first switch tube 14 and then to the inverter circuit bus.

[0042] Since the impedance of the first inductor 13 and the body diode 22 a is relatively large, the circuit loss is relatively high and the working efficiency is relatively low.

[0043] Reference Figure 1 As shown, an embodiment of the present disclosure provides a bidirectional current conversion circuit, which includes a main circuit 1 and a bypass circuit 2. The main circuit 1 is a bidirectional BUCK-BOOST circuit. The main circuit 1 has a first end 10 and a second end 20. The first interface 10a and the second interface 10b of the first end 10 are electrically connected to the battery, respectively, and the third interface 20a and the fourth interface 20b of the second end 20 are electrically connected to the inverter circuit bus, respectively. The two ends of the bypass circuit 2 are electrically connected to the first interface 10a and the third interface 20a, respectively. The impedance of the bypass circuit 2 is less than the impedance of the main circuit 1. The bypass circuit 2 is used to connect the first interface 10a and the third interface 20a when the voltage at the first end 10 is greater than a preset voltage value.

[0044] The first interface 10a is connected to the positive electrode of the battery, and the second interface 10b is connected to the negative electrode of the battery.

[0045] When the battery is discharging and the voltage Vin at the first terminal 10 is less than a preset voltage value, the main circuit 1 operates in a boost mode, thereby achieving an output voltage Vout higher than the input voltage Vin. When the battery is discharging and the voltage Vin at the first terminal 10 is greater than the preset voltage value, the bypass circuit 2 is turned on, and the current output by the battery flows through the bypass circuit 2, without flowing through, or with a smaller portion flowing through, the components in the main circuit 1.

[0046] Since the impedance of the bypass circuit 2 is smaller than that of the main circuit 1, when the battery is discharging and the voltage Vin at the first terminal 10 is greater than a preset voltage value, the loss of current flowing through the bypass circuit 2 or through both the bypass circuit 2 and the main circuit 1 is smaller than the loss of current flowing only through the main circuit 1, thereby improving the operating efficiency of the bidirectional current conversion circuit.

[0047] In some embodiments, the main circuit 1 may include a first capacitor 11, a second capacitor 12, a first inductor 13, a first switching tube 14 and a second switching tube 15. The first capacitor 11 is electrically connected to the first interface 10a and the second interface 10b, respectively. The second capacitor 12 is electrically connected to the third interface 20a and the fourth interface 20b, respectively. The first end of the first inductor 13 is electrically connected to the first end of the first capacitor 11, the two ends of the first switching tube 14 are electrically connected to the second end of the first inductor 13 and the first end of the second capacitor 12, respectively. The first end of the second switching tube 15 is electrically connected to the second end of the first inductor 13, and the second end of the second switching tube 15 is electrically connected to the second end of the first capacitor 11 and the second end of the second capacitor 12.

[0048] When the battery is discharged and the input voltage Vin of the first terminal 10 is less than the preset voltage value, the main circuit 1 is in the boost mode. At this time, the operation of the main circuit 1 includes two stages:

[0049] 1. The second switch tube 15 is turned on

[0050] When the second switch 15 is turned on, the input voltage Vin at the first terminal 10 forms a closed loop through the first inductor 13 and the second switch 15. At this point, the current output by the battery flows through the first inductor 13, causing the first inductor 13 to begin storing energy. Because the second switch 15 is turned on, the output voltage Vout across the second capacitor 12 remains unchanged, and the current of the inverter circuit bus is provided by the second capacitor 12.

[0051] During this stage, the current in the first inductor 13 gradually increases, and the energy stored in the first inductor 13 also increases accordingly.

[0052] 2. The second switch tube 15 is turned off

[0053] When the second switch 15 is turned off, the circuit between the input voltage Vin at the first terminal 10 and the first inductor 13 is blocked. Because inductors cannot change their current suddenly, the first inductor 13 attempts to maintain a constant current. Consequently, the energy stored in the first inductor 13 is transferred to the output terminal via the body diode 22a of the first switch 14 and the second capacitor 12, causing the voltage across the second capacitor 12 to increase.

[0054] During this process, the energy released by the first inductor 13 plus the input voltage Vin act together on the second capacitor 12 and the inverter circuit bus, making the output voltage Vout of the second end 20 higher than the input voltage Vin of the first end 10 .

[0055] In the main circuit 1, the on and off time (i.e., duty cycle) of the second switch 15 can be controlled to adjust the output voltage Vout. A larger duty cycle results in a longer on-time of the second switch 15, more energy stored in the first inductor 13, and a higher output voltage Vout. Conversely, a smaller duty cycle results in a lower output voltage Vout. The duty cycle of the second switch 15 can be set based on the required voltage at the inverter circuit busbar.

[0056] When the battery is discharging and the input voltage Vin at the first terminal 10 is greater than a preset voltage value, the main circuit 1 is not in the boost mode, that is, the second switch 15 is in the off state. At this point, the majority of the battery output current flows through the bypass circuit 2, with no or only a small portion flowing through the main circuit 1. Because the current flowing through the main circuit 1 is small and negligible, the subsequent embodiments will illustrate the ideal effect of the battery output current flowing only through the bypass circuit 2 and not through the main circuit 1, unless otherwise specified.

[0057] For example, the battery discharge voltage range is 0-500V, and during the battery discharge process, the discharge voltage will gradually decrease, and the preset voltage value is 400V.

[0058] When the battery discharge voltage is between 400V and 500V, main circuit 1 is not in boost mode, meaning second switch 15 is off. The battery output current flows only through bypass circuit 2 and then to the busbar side of second terminal 20. If the input voltage Vin at first terminal 10 is 480V, the impedance of bypass circuit 2 causes a 5V voltage drop, resulting in an output voltage Vout of 475V at second terminal 20.

[0059] If the bypass circuit 2 is not provided, the current output by the battery will flow through the main circuit 1, namely, the first inductor 13 and the body diode 22a of the first switch tube 14. The impedance of the first inductor 13 and the body diode 22a of the first switch tube 14 causes a voltage drop of 50V, so the output voltage Vout of the second end 20 is 430V.

[0060] It can be seen from this that providing a bypass circuit 2 with a smaller impedance can reduce the loss in the bidirectional current conversion circuit and improve the working efficiency.

[0061] In some embodiments, the main circuit 1 may further include a second inductor 16, a third switching tube 17 and a fourth switching tube 18, the first end of the second inductor 16 is electrically connected to the first end of the first capacitor 11, the two ends of the third switching tube 17 are electrically connected to the second end of the second inductor 16 and the first end of the second capacitor 12 respectively, the first end of the fourth switching tube 18 is electrically connected to the second end of the second inductor 16, and the second end of the fourth switching tube 18 is electrically connected to the second end of the first capacitor 11 and the second end of the second capacitor 12.

[0062] In this way, the first circuit composed of the first inductor 13 and the second switching tube 15 and the second circuit composed of the second inductor 16 and the fourth switching tube 18 can be regarded as two circuits arranged in parallel between the first capacitor 11 and the second capacitor 12. The two circuits can share the output power of the battery, and then the main circuit 1 can withstand a larger output power, which is conducive to meeting the required power range of a wider load.

[0063] When the battery is discharged and the input voltage Vin of the first terminal 10 is less than the preset voltage value, the main circuit 1 is in the boost mode. At this time, the operation of the main circuit 1 includes two stages:

[0064] 1. The second switch tube 15 and the fourth switch tube 18 are turned on (refer to Figure 5 shown)

[0065] When the second switch 15 is turned on, the input voltage Vin at the first terminal 10 forms a closed loop through the first inductor 13 and the second switch 15. At this point, the battery output current flows through the first inductor 13, causing the first inductor 13 to begin storing energy. Because the second switch 15 is in the on state, the output voltage Vout across the second capacitor 12 remains unchanged, and the current flowing through the inverter circuit bus is provided by the second capacitor 12. During this phase, the current flowing through the first inductor 13 gradually increases, and the energy stored in the first inductor 13 also increases accordingly.

[0066] When the fourth switch 18 is turned on, the input voltage Vin at the first terminal 10 forms a closed loop through the second inductor 16 and the fourth switch 18. At this point, the battery output current flows through the second inductor 16, causing the second inductor 16 to begin storing energy. Because the fourth switch 18 is in the on state, the output voltage Vout across the second capacitor 12 remains unchanged, and the current flowing through the inverter circuit bus is provided by the second capacitor 12. During this phase, the current flowing through the second inductor 16 gradually increases, and the energy stored in the second inductor 16 also increases accordingly.

[0067] 2. The second switch tube 15 and the fourth switch tube 18 are turned off (refer to Figure 6 shown)

[0068] When the second switch 15 is turned off, the circuit between the input voltage Vin at the first terminal 10 and the first inductor 13 is blocked. Since inductors cannot change their current suddenly, the first inductor 13 attempts to maintain the current flowing through it. Therefore, the energy stored in the first inductor 13 is transferred to the output terminal via the body diode 22a of the first switch 14 and the second capacitor 12, causing the voltage across the second capacitor 12 to increase. During this process, the energy released by the first inductor 13 plus the input voltage Vin acts on the second capacitor 12 and the inverter circuit bus, causing the output voltage Vout of the second terminal 20 to be higher than the input voltage Vin at the first terminal 10.

[0069] When the fourth switch 18 is turned off, the circuit between the input voltage Vin at the first terminal 10 and the second inductor 16 is blocked. Since inductors cannot change their current suddenly, the second inductor 16 attempts to maintain the current flowing through it. Therefore, the energy stored in the second inductor 16 is transferred to the output terminal via the body diode 22a of the third switch 17 and the second capacitor 12, causing the voltage across the second capacitor 12 to increase. During this process, the energy released by the second inductor 16, combined with the input voltage Vin, acts on the second capacitor 12 and the inverter circuit bus, causing the output voltage Vout of the second terminal 20 to be higher than the input voltage Vin at the first terminal 10.

[0070] Based on the same principle, in main circuit 1, the on and off time (i.e., duty cycle) of fourth switch 18 can be controlled to adjust the output voltage Vout. A larger duty cycle results in a longer on-time of fourth switch 18, more energy stored in second inductor 16, and a higher output voltage Vout. Conversely, a smaller duty cycle results in a lower output voltage Vout. The duty cycle of fourth switch 18 can be set based on the required voltage at the inverter circuit busbar.

[0071] In some embodiments, the first switch tube 14 , the second switch tube 15 , the third switch tube 17 and the fourth switch tube 18 are either IGBT tubes or MOSFET tubes.

[0072] A switching tube refers to an electronic switching element that switches quickly between the "on" and "off" states to achieve the purpose of quickly switching current in the circuit. Among them, IGBT tubes (insulated gate bipolar transistors) and MOSFET tubes (metal-oxide-semiconductor field-effect transistors) can both be used as switching tubes. IGBT tubes have the characteristics of small on-resistance and high voltage resistance, and are suitable for low-frequency and high-power occasions; MOSFET tubes have good high-frequency characteristics and high operating frequency, but large on-resistance and high power consumption in high-voltage and high-current situations, and are suitable for small and medium power or high switching frequency occasions.

[0073] In the embodiment of the present disclosure, the type of each switch tube can be matched and selected according to parameters such as the switching frequency, cost, etc. of the first switch tube 14, the second switch tube 15, the third switch tube 17, and the fourth switch tube 18. Figures 1 to 3 As shown, the present disclosure is described by taking the example that the first switch tube 14 , the second switch tube 15 , the third switch tube 17 and the fourth switch tube 18 are all IGBT tubes.

[0074] In some embodiments, the first switching transistor 14, the second switching transistor 15, the third switching transistor 17, and the fourth switching transistor 18 all have a body diode 22a. The body diode 22a acts as a reverse protection for the switching transistor. When the switching transistor is in the off state, if its drain (or collector) voltage suddenly exceeds the source (or emitter) voltage, the body diode 22a turns on, clamping the reverse voltage to the forward conduction voltage drop of the body diode 22a, thereby protecting the switching transistor from damage by the reverse voltage and reducing the risk of device damage caused by transient voltage or incorrect connection in the circuit.

[0075] The provision of the body diode 22 a can simplify circuit design. For example, the body diode 22 a of the switch tube can be used as a rectifier diode, thereby reducing the number of external components and costs.

[0076] In some embodiments, reference Figure 2 As shown, the bypass circuit 2 includes a diode 21. The anode of the diode 21 is electrically connected to the first interface 10a, and the cathode of the diode 21 is electrically connected to the third interface 20a. The diode 21 can clamp the voltage drop between the first terminal 10 and the second terminal 20 to the diode 21's own voltage drop. This ensures that the battery output current does not flow through the first inductor 13, the body diode 22a of the first switch 14, or the body diode 22a of the second inductor 16 and the third switch 17, but only through the diode 21. Due to the low impedance of the diode 21, the loss of the bidirectional current conversion circuit can be reduced, thereby improving the operating efficiency of the bidirectional current conversion circuit.

[0077] In some embodiments, reference Figure 3 As shown, the bypass circuit 2 may include a fifth switch tube 22 and a controller 23. The two ends of the fifth switch tube 22 are electrically connected to the first interface 10a and the third interface 20a, respectively. The conduction direction of the fifth switch tube 22 is from the first interface 10a to the third interface 20a. The controller 23 is electrically connected to the first end 10, the second end 20, and the fifth switch tube 22. The controller 23 can detect the voltage values ​​of the first end 10 and the second end 20. The controller 23 is used to: when the voltage at the first end 10 is greater than the preset voltage value, control the fifth switch tube 22 to conduct.

[0078] The fifth switch tube 22 can be any one of an IGBT tube or a MOSFET tube. Taking the fifth switch tube 22 as an N-type MOSFET tube as an example, the source (S pole) of the fifth switch tube 22 is electrically connected to the first interface 10a, the drain (D pole) of the fifth switch tube 22 is electrically connected to the third interface 20a, and the gate (G pole) of the fifth switch tube 22 is electrically connected to the controller 23. The controller 23 is also electrically connected to the first end 10 and the second end 20.

[0079] The controller 23 can detect the voltage values ​​of the first terminal 10 and the second terminal 20. If the voltage of the first terminal 10 (i.e., the input voltage Vin) is less than a preset voltage value, the controller 23 controls the fifth switch 22 to turn off. At this time, the main circuit 1 is in the boost mode, and the current flows through the first loop formed by the first inductor 13 and the second switch 15, the second loop formed by the second inductor 16 and the fourth switch 18, or flows to the second terminal 20.

[0080] If the voltage at the first terminal 10 (i.e., the input voltage Vin) is greater than a preset voltage value, the controller turns on the fifth switch 22. At this point, the main circuit 1 stops boosting, meaning the second and fourth switches 15 and 18 are turned off. Turning on the fifth switch 22 ensures that the battery output current does not flow through the first inductor 13, the body diode 22a of the first switch 14, or the body diode 22a of the second inductor 16 and the third switch 17, but only through the fifth switch 22. Because the fifth switch 22 has a low impedance, it reduces losses in the bidirectional current conversion circuit and improves its efficiency.

[0081] In some embodiments, reference Figure 1 As shown, the bypass circuit 2 includes a diode 21, a fifth switch tube 22 and a controller 23. The anode of the diode 21 is electrically connected to the first interface 10a, the cathode of the diode 21 is electrically connected to the third interface 20a, the fifth switch tube 22 and the diode 21 are arranged in parallel, and the conduction direction of the fifth switch tube 22 is from the first interface 10a to the third interface 20a. The controller 23 is electrically connected to the first end 10, the second end 20 and the fifth switch tube 22. The controller 23 is used to: when the voltage at the first end 10 is greater than the preset voltage value, control the fifth switch tube 22 to conduct.

[0082] Still taking the fifth switch tube 22 as an N-type MOSFET tube as an example, the source (S pole) of the fifth switch tube 22 is electrically connected to the first interface 10a, the drain (D pole) of the fifth switch tube 22 is electrically connected to the third interface 20a, and the gate (G pole) of the fifth switch tube 22 is electrically connected to the controller 23. The controller 23 is also electrically connected to the first terminal 10 and the second terminal 20.

[0083] The controller 23 can detect the voltage values ​​of the first terminal 10 and the second terminal 20. If the voltage at the first terminal 10 (i.e., the input voltage Vin) is less than a preset voltage value, the controller controls the fifth switch 22 to turn off. At this time, the main circuit 1 is in the boost mode. The current flows through the first loop formed by the first inductor 13 and the second switch 15, the second loop formed by the second inductor 16 and the fourth switch 18, or flows to the second terminal 20, but does not flow through the fifth switch 22 and the diode 21.

[0084] If the voltage at the first terminal 10 (i.e., the input voltage Vin) is greater than a preset voltage value, the controller turns on the fifth switch 22. At this point, the main circuit 1 stops boosting, meaning the second and fourth switches 15 and 18 are turned off. Turning on the fifth switch 22 ensures that the battery output current does not flow through the first inductor 13, the body diode 22a of the first switch 14, and / or the body diode 22a of the second inductor 16 and the third switch 17, but only through the fifth switch 22. Because the fifth switch 22 has a low impedance, it reduces losses in the bidirectional current conversion circuit and improves its efficiency.

[0085] The diode 21 provided in parallel with the fifth switch tube 22 can reduce the circuit loss caused by the delayed conduction of the fifth switch tube 22. The specific process is as follows:

[0086] If the voltage at the first end 10 (i.e., the input voltage Vin) is greater than the preset voltage value, the main circuit 1 stops the boosting operation, i.e., the second switch tube 15 and the fourth switch tube 18 are turned off. After the controller 23 detects that the voltage at the first end 10 is greater than the preset voltage value, it controls the fifth switch tube 22 to turn on. It takes a certain amount of time for the controller 23 to detect, identify, and make corresponding judgments on the voltage, which can be defined as a first time length.

[0087] When the voltage at the first end 10 (i.e., the input voltage Vin) is greater than a preset voltage value, the current output by the battery flows through the diode 21 within a first period of time after the main circuit 1 stops the boost operation. After the first period of time, the fifth switch tube 22 is turned on. Since the impedance of the fifth switch tube 22 is smaller than that of the diode 21, the current output by the battery changes from flowing through the diode 21 to flowing through the fifth switch tube 22, further reducing the loss of the bidirectional current conversion circuit when it is not working in the boost mode.

[0088] The setting of the diode 21 can prevent the current output by the battery from flowing through the first inductor 13, the body diode 22a of the first switch tube 14 and / or the second inductor 16, the body diode 22a of the third switch tube 17 within the first period of time after the main circuit 1 stops the boosting operation, thereby causing large losses in the first inductor 13, the body diode 22a of the first switch tube 14, the second inductor 16, and the body diode 22a of the third switch tube 17.

[0089] In some embodiments, the fifth switch 22 includes a body diode 22a. The conduction direction of the body diode 22a is from the first interface 10a to the third interface 20a. The body diode 22a of the fifth switch 22 can form a parallel circuit with the diode 21 during the first duration. The body diode 22a and the diode 21 share the current, thereby preventing the battery output current from being too high and damaging the body diode 22a.

[0090] Based on the same concept, an embodiment of the present disclosure further provides a photovoltaic energy storage converter, which may include a bidirectional current conversion circuit, an inverter circuit, a battery, and a load as in any of the above embodiments.

[0091] The first terminal 10 of the main circuit 1 is electrically connected to the battery, the second terminal 20 of the main circuit 1 is electrically connected to the busbar (ie, DC side) of the inverter circuit, and the AC side of the inverter circuit is connected to the load.

[0092] The energy output by the battery flows to the inverter circuit through the main circuit 1, and is then converted into alternating current by the inverter circuit and supplied to the load, thereby realizing the normal operation of the load itself.

[0093] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0094] It is understood that in this disclosure, "plurality" refers to two or more than two, and other quantifiers are similar. "And / or" describes the association relationship of related objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects before and after are in an "or" relationship. The singular forms "a", "the" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0095] It will be further understood that the terms "first," "second," and the like are used to describe various types of information, but such information should not be limited to these terms. These terms are used solely to distinguish information of the same type from one another and do not indicate a particular order or level of importance. In fact, the terms "first," "second," and the like are fully interchangeable. For example, first information could be referred to as second information, and similarly, second information could be referred to as first information without departing from the scope of this disclosure.

[0096] It can be further understood that the terms "center", "longitudinal", "lateral", "front", "back", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation.

[0097] It is further understood that, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed connections, detachable connections, or integral molding; they may refer to mechanical connections, electrical connections, or communication between them; they may refer to direct connections without any other components between them, or indirect connections through an intermediary; they may refer to internal communication between two elements, or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

[0098] It is further understood that although operations are described in a particular order in the drawings in the embodiments of the present disclosure, this should not be construed as requiring that the operations be performed in the particular order shown or in a serial order, or that all of the operations shown be performed to obtain the desired results. In certain circumstances, multitasking and parallel processing may be advantageous.

[0099] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the solutions disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present disclosure are indicated by the claims.

[0100] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the scope of the appended claims.

Claims

1. A bidirectional current conversion circuit, characterized in that: The bidirectional current conversion circuit comprises a main circuit (1) and a bypass circuit (2); The main circuit (1) is a bidirectional BUCK-BOOST circuit, and the main circuit (1) has a first end (10) and a second end (20), wherein the first interface (10a) and the second interface (10b) of the first end (10) are electrically connected to the battery, respectively, and the third interface (20a) and the fourth interface (20b) of the second end (20) are electrically connected to the inverter circuit busbar, respectively; The two ends of the bypass circuit (2) are electrically connected to the first interface (10a) and the third interface (20a), respectively; the impedance of the bypass circuit (2) is smaller than the impedance of the main circuit (1); and the bypass circuit (2) is used to connect the first interface (10a) and the third interface (20a) when the voltage at the first end (10) is greater than a preset voltage value.

2. The bidirectional current conversion circuit according to claim 1, wherein: The main circuit (1) comprises a first capacitor (11), a second capacitor (12), a first inductor (13), a first switch tube (14) and a second switch tube (15); the first capacitor (11) is electrically connected to the first interface (10a) and the second interface (10b) respectively; the second capacitor (12) is electrically connected to the third interface (20a) and the fourth interface (20b) respectively; the first end of the first inductor (13) is electrically connected to the first end of the first capacitor (11); the two ends of the first switch tube (14) are electrically connected to the second end of the first inductor (13) and the first end of the second capacitor (12) respectively; the first end of the second switch tube (15) is electrically connected to the second end of the first inductor (13); and the second end of the second switch tube (15) is electrically connected to the second end of the first capacitor (11) and the second end of the second capacitor (12).

3. The bidirectional current conversion circuit according to claim 2, characterized in that: The main circuit (1) further includes a second inductor (16), a third switch tube (17) and a fourth switch tube (18); the first end of the second inductor (16) is electrically connected to the first end of the first capacitor (11); the two ends of the third switch tube (17) are electrically connected to the second end of the second inductor (16) and the first end of the second capacitor (12), respectively; the first end of the fourth switch tube (18) is electrically connected to the second end of the second inductor (16); and the second end of the fourth switch tube (18) is electrically connected to the second end of the first capacitor (11) and the second end of the second capacitor (12).

4. The bidirectional current conversion circuit according to claim 3, characterized in that: The first switch tube (14), the second switch tube (15), the third switch tube (17) and the fourth switch tube (18) are each any one of an IGBT tube or a MOSFET tube.

5. The bidirectional current conversion circuit according to claim 3, wherein: The first switching tube (14), the second switching tube (15), the third switching tube (17) and the fourth switching tube (18) all have a body diode (22a).

6. The bidirectional current conversion circuit according to claim 1, wherein: The bypass circuit (2) comprises a diode (21), the anode of the diode (21) is electrically connected to the first interface (10a), and the cathode of the diode (21) is electrically connected to the third interface (20a).

7. The bidirectional current conversion circuit according to claim 1, wherein: The bypass circuit (2) comprises a fifth switch tube (22) and a controller (23), wherein two ends of the fifth switch tube (22) are electrically connected to the first interface (10a) and the third interface (20a) respectively, and the conduction direction of the fifth switch tube (22) is from the first interface (10a) to the third interface (20a); The controller (23) is electrically connected to the first end (10), the second end (20), and the fifth switch tube (22). The controller (23) is used to control the fifth switch tube (22) to be turned on when the voltage of the first end (10) is greater than a preset voltage value.

8. The bidirectional current conversion circuit according to claim 1, wherein: The bypass circuit (2) comprises a diode (21), a fifth switch tube (22) and a controller (23); The anode of the diode (21) is electrically connected to the first interface (10a), and the cathode of the diode (21) is electrically connected to the third interface (20a); The fifth switch tube (22) and the diode (21) are arranged in parallel, and the conduction direction of the fifth switch tube (22) is that the power flows from the first interface (10a) to the third interface (20a); The controller (23) is electrically connected to the first end (10), the second end (20), and the fifth switch tube (22). The controller (23) is used to control the fifth switch tube (22) to be turned on when the voltage of the first end (10) is greater than a preset voltage value.

9. The bidirectional current conversion circuit according to claim 7 or 8, characterized in that: The fifth switch tube (22) has a body diode (22a), and the conducting direction of the body diode (22a) is from the first interface (10a) to the third interface (20a).

10. A photovoltaic energy storage converter, characterized in that: The photovoltaic energy storage converter includes a bidirectional current conversion circuit according to any one of claims 1 to 9.

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