Bidirectional buck-boost circuit and system

Abstract

The utility model discloses a bidirectional buck-boost circuit and system, and the circuit comprises a first switching unit which is used for converting a first DC voltage, outputting a first voltage, a second voltage, a third voltage, and a fourth voltage, or outputting a second target voltage converted by a transformer; the transformer is used for converting the received first voltage, second voltage, third voltage and fourth voltage into first target voltage, or converting the received fifth voltage, sixth voltage, seventh voltage and eighth voltage into second target voltage; the second switching unit is used for outputting the first target voltage or converting the second direct-current voltage and outputting a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage. The first direct current voltage is converted through the first switching unit, the second direct current voltage is converted through the second switching unit, voltage ripples of the first target voltage and the second target voltage output by the transformer are reduced, and the EMI problem is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to a bidirectional step-up and step-down circuit and system. Background Art

[0002] With the rapid development of new energy technologies, energy storage systems are usually connected to the DC bus through a buck-boost circuit to achieve energy flow between the energy storage system and the DC bus, thereby realizing the control and efficient utilization of energy in the energy storage system.

[0003] However, the two-level buck-boost circuit in the prior art converts the received DC voltage into a first voltage and a second voltage to the transformer. Since the voltage difference between the first voltage and the second voltage is large, the target voltage ripple output by the transformer is large, making the output target voltage prone to EMI (electromagnetic interference) problems. Utility Model Content

[0004] The utility model provides a bidirectional buck-boost circuit and system, which are used to solve the problem in the prior art that the target voltage ripple output by the buck-boost circuit is large and EMI is easily generated.

[0005] In a first aspect, an embodiment of the present invention provides a bidirectional buck-boost circuit, comprising: a first switching unit, a transformer, and a second switching unit;

[0006] The first switching unit, the transformer and the second switching unit are connected in sequence;

[0007] The first switching unit is configured to convert the received first DC voltage and output a first voltage, a second voltage, a third voltage, and a fourth voltage within a cycle, or output a second target voltage converted by the transformer, wherein the first voltage is the same as the first DC voltage, the fourth voltage is an inverted voltage of the first voltage, the second voltage is less than the first voltage, and the third voltage is an inverted voltage of the second voltage;

[0008] The transformer is configured to convert the received first voltage, the second voltage, the third voltage, and the fourth voltage into a first target voltage, or to convert the received fifth voltage, the sixth voltage, the seventh voltage, and the eighth voltage into the second target voltage.

[0009] The second switching unit is used to output the first target voltage, or convert the received second DC voltage, and output the fifth voltage, the sixth voltage, the seventh voltage and the eighth voltage within one cycle, wherein the fifth voltage is the same as the second DC voltage, the eighth voltage is the inverted voltage of the fifth voltage, the sixth voltage is less than the fifth voltage, and the seventh voltage is the inverted voltage of the sixth voltage.

[0010] In a possible implementation, the first switching unit includes a first bridge arm, a second bridge arm, and a third bridge arm, wherein the first bridge arm includes a first switch tube and a second switch tube, the second bridge arm includes a third switch tube and a fourth switch tube, and the third bridge arm includes a fifth switch tube and a sixth switch tube;

[0011] The first end of the first switching tube serves as a positive input and output end of the first switching unit, the second end of the first switching tube is electrically connected to the first end of the second switching tube, the first end of the transformer, and the first end of the third switching tube, and the second end of the second switching tube serves as a negative input and output end of the first switching unit;

[0012] The second end of the third switch tube is electrically connected to the first end of the fourth switch tube, and the second end of the fourth switch tube is connected between the positive input and output ends of the first switching unit and the negative input and output ends of the first switching unit;

[0013] The first end of the fifth switching tube serves as the positive input and output end of the first switching unit, the second end of the fifth switching tube is electrically connected to the first end of the sixth switching tube and the second end of the transformer, and the second end of the sixth switching tube serves as the negative input and output end of the first switching unit.

[0014] In a possible implementation, the first switching unit further includes: a first capacitor and a second capacitor, wherein:

[0015] The first capacitor is connected between the second end of the fourth switch tube and the positive input and output of the first switching unit;

[0016] The second capacitor is connected between the second end of the fourth switch tube and the negative input and output of the first switching unit.

[0017] In a possible implementation, the second switching unit includes a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm, wherein the fourth bridge arm includes a seventh switch tube and an eighth switch tube, the fifth bridge arm includes a ninth switch tube and a tenth switch tube, and the sixth bridge arm includes an eleventh switch tube and a twelfth switch tube;

[0018] The first end of the seventh switching tube serves as the positive input and output end of the second switching unit, the second end of the seventh switching tube is electrically connected to the first end of the eighth switching tube, the third end of the transformer, and the first end of the ninth switching tube, and the second end of the eighth switching tube serves as the negative input and output end of the second switching unit;

[0019] The second end of the ninth switch tube is electrically connected to the first end of the tenth switch tube, and the second end of the tenth switch tube is connected between the positive input and output ends of the second switching unit and the negative input and output ends of the second switching unit;

[0020] The first end of the eleventh switching tube serves as the positive input and output end of the second switching unit, the second end of the eleventh switching tube is electrically connected to the first end of the twelfth switching tube and the fourth end of the transformer, and the second end of the twelfth switching tube serves as the negative input and output end of the second switching unit.

[0021] In a possible implementation, the second switching unit includes: a third capacitor and a fourth capacitor, wherein:

[0022] The third capacitor is connected between the second end of the tenth switch tube and the positive input and output end of the second switching unit;

[0023] The fourth capacitor is connected between the second end of the tenth switch tube and the negative input and output end of the second switching unit.

[0024] In a possible implementation, the device further includes: a fifth capacitor, a sixth capacitor, a first inductor, and a second inductor;

[0025] The first end of the fifth capacitor is electrically connected to the second end of the first switching transistor and the first end of the second switching transistor, the second end of the fifth capacitor is electrically connected to the first end of the first inductor, and the second end of the first inductor is electrically connected to the first end of the transformer;

[0026] The first end of the sixth capacitor is electrically connected to the third end of the transformer, the second end of the sixth capacitor is electrically connected to the first end of the second inductor, and the second end of the second inductor is electrically connected to the second end of the seventh switching tube and the first end of the eighth switching tube.

[0027] In a second aspect, an embodiment of the present invention further provides a bidirectional buck-boost system, comprising a bidirectional buck-boost circuit as described in any one of the first aspects, and an energy storage system and a bus capacitor connected to the bidirectional buck-boost circuit.

[0028] The beneficial effects of the embodiments of the present utility model are as follows:

[0029] The embodiment of the present utility model provides a bidirectional buck-boost circuit and system, which includes: a first switching unit, a transformer and a second switching unit; the first switching unit, the transformer and the second switching unit are connected in sequence, and the input end of the first switching unit is electrically connected to the output end of the energy storage system, and the output end of the second switching unit is electrically connected to the DC bus; the first switching unit is used to convert the received first DC voltage and output the first voltage, the second voltage, the third voltage and the fourth voltage in one cycle, or output the second target voltage converted by the transformer, wherein the first voltage is the same as the first DC voltage, the fourth voltage is the inverse voltage of the first voltage, and the second voltage is the inverse voltage of the first voltage. The voltage is less than the first voltage, and the third voltage is the inverted voltage of the second voltage; the transformer is used to convert the received first voltage, second voltage, third voltage and fourth voltage into the first target voltage, or convert the received fifth voltage, sixth voltage, seventh voltage and eighth voltage into the second target voltage; the second switching unit is used to output the first target voltage, or convert the received second DC voltage, and output the fifth voltage, sixth voltage, seventh voltage and eighth voltage within one cycle, wherein the fifth voltage is the same as the second DC voltage, the eighth voltage is the inverted voltage of the fifth voltage, the sixth voltage is less than the fifth voltage, and the seventh voltage is the inverted voltage of the sixth voltage. The present application converts the first DC voltage into the first voltage, the second voltage, the third voltage and the fourth voltage through the first switching unit, and converts the second DC voltage into the fifth voltage, the sixth voltage, the seventh voltage and the eighth voltage through the second switching unit, so as to reduce the voltage ripple of the first target voltage and the second target voltage output by the transformer and reduce EMI problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 A circuit diagram of a two-level buck-boost circuit provided by the prior art;

[0032] Figure 2 A schematic structural diagram of a bidirectional buck-boost circuit provided in an embodiment of the present application;

[0033] Figure 3 A circuit diagram of a bidirectional buck-boost circuit provided in an embodiment of the present application;

[0034] Figure 4 A circuit diagram of another bidirectional buck-boost circuit provided in an embodiment of the present application;

[0035] Figure 5 A circuit diagram of another bidirectional buck-boost circuit provided in an embodiment of the present application;

[0036] Figure 6 A flow chart of a bidirectional buck-boost control method provided in an embodiment of the present application;

[0037] Figure 7 A schematic structural diagram of a bidirectional buck-boost system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the present invention more clearly apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0039] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0040] With the rapid development of new energy technologies, energy storage systems are usually connected to the DC bus through a buck-boost circuit to achieve energy flow between the energy storage system and the DC bus, thereby realizing the control and efficient utilization of energy in the energy storage system.

[0041] However, the two-level buck-boost circuit in the prior art, such as Figure 1 Figure 1 shows a schematic diagram of the circuit structure of a two-level buck-boost circuit according to the prior art. The circuit includes switches Q_1, Q_2, Q_3, Q_4, Q_5, Q_6, Q_7, Q_8, capacitors C_1 and C_2, a transformer T_1, and an inductor L_1. The circuit converts a received DC voltage Ui into a first voltage Ui or a second voltage -Ui, which is then transmitted to transformer T_1. Due to the large voltage difference between the first voltage Ui and the second voltage -Ui, the target voltage output by transformer T_1 has a large ripple, which reduces EMI issues.

[0042] Based on the above problems, Figure 2, which is a structural diagram of a bidirectional buck-boost circuit provided in an embodiment of the present application, includes: a first switching unit 201, a transformer T, and a second switching unit 202;

[0043] The first switching unit 201, the transformer T, and the second switching unit 202 are connected in sequence, and the input end of the first switching unit 201 is electrically connected to the output end of the energy storage system, and the output end of the second switching unit 202 is electrically connected to the DC bus;

[0044] The first switching unit 201 is configured to convert the received first DC voltage and output a first voltage, a second voltage, a third voltage, and a fourth voltage within one cycle, or output a second target voltage converted by the transformer T, wherein the first voltage is the same as the first DC voltage, the fourth voltage is an inverse voltage of the first voltage, the second voltage is less than the first voltage, and the third voltage is an inverse voltage of the second voltage;

[0045] a transformer T, configured to convert the received first voltage, second voltage, third voltage, and fourth voltage into a first target voltage, or to convert the received fifth voltage, sixth voltage, seventh voltage, and eighth voltage into a second target voltage;

[0046] The second switching unit 202 is used to output the first target voltage, or convert the received second DC voltage, and output a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage within one cycle, wherein the fifth voltage is the same as the second DC voltage, the eighth voltage is the inverted voltage of the fifth voltage, the sixth voltage is less than the fifth voltage, and the seventh voltage is the inverted voltage of the sixth voltage.

[0047] An embodiment of the present utility model provides a bidirectional buck-boost circuit, which converts a first DC voltage into a first voltage, a second voltage, a third voltage and a fourth voltage through a first switching unit, and converts a second DC voltage into a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage through a second switching unit, so as to reduce the voltage ripple of the output first target voltage and the second target voltage and reduce EMI problems.

[0048] In the embodiment of the present application, when the first DC voltage received by the first switching unit 201 is Ui, since the first voltage is the same as the first DC voltage, the first voltage is Ui; the fourth voltage is the inverse voltage of the first voltage, the fourth voltage is -Ui; the second voltage is less than the first voltage, the second voltage is The third voltage is the inverse voltage of the second voltage.

[0049] When the first DC voltage received by the second switching unit 202 is Ui, since the fifth voltage is the same as the second DC voltage, the fifth voltage is Ui; the eighth voltage is the inverse voltage of the fifth voltage, and the eighth voltage is -Ui; the sixth voltage is less than the fifth voltage, and the sixth voltage is The seventh voltage is the inverted voltage of the sixth voltage.

[0050] It should be noted that the transformer T is used to increase or decrease the received first voltage, second voltage, third voltage and fourth voltage to the first target voltage, or to increase or decrease the received fifth voltage, sixth voltage, seventh voltage and eighth voltage to the second target voltage.

[0051] In one possible implementation, Figure 3 As shown, it is a circuit schematic diagram of a bidirectional buck-boost circuit provided in an embodiment of the present application. The first switching unit 201 includes a first bridge arm 301, a second bridge arm 302 and a third bridge arm 303. The first bridge arm 301 and the third bridge arm 303 are connected in parallel between the positive output end of the energy storage system and the negative output end of the energy storage system. One end of the second bridge arm 302 is electrically connected to the positive output end of the energy storage system and the negative output end of the energy storage system, and the other end of the second bridge arm 302 is electrically connected to the midpoint of the first bridge arm 301.

[0052] Specifically, the first bridge arm 301 includes a first switch tube Q1 and a second switch tube Q2, the second bridge arm 302 includes a third switch tube Q3 and a fourth switch tube Q4, and the third bridge arm 303 includes a fifth switch tube Q5 and a sixth switch tube Q6;

[0053] A first end of the first switch tube Q1 is electrically connected to the positive output end of the energy storage system, a second end of the first switch tube Q1 is electrically connected to the first end of the second switch tube Q2, the first end of the transformer T, and the first end of the third switch tube Q3, and a second end of the second switch tube Q2 is electrically connected to the negative output end of the energy storage system;

[0054] The second end of the third switch tube Q3 is electrically connected to the first end of the fourth switch tube Q4, and the second end of the fourth switch tube Q4 is electrically connected to the positive output end of the energy storage system and the negative output end of the energy storage system;

[0055] A first end of the fifth switch tube Q5 is electrically connected to the positive output end of the energy storage system, a second end of the fifth switch tube Q5 is electrically connected to a first end of the sixth switch tube Q6 and the second end of the transformer T, and a second end of the sixth switch tube Q6 is electrically connected to the negative output end of the energy storage system.

[0056] In the embodiment of the present application, the first switching unit 201 converts the received first DC voltage Ui by controlling the opening and closing of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6, and outputs the first voltage Ui, the second voltage Ui and the second voltage Ui. The third voltage and a fourth voltage -Ui.

[0057] Specifically, the first switch tube Q1 and the sixth switch tube Q6 are controlled to be turned on to output the first voltage Ui;

[0058] Control the first switch tube Q1 to be turned off, and control the third switch tube Q3, the fourth switch tube Q4 and the sixth switch tube Q6 to be turned on, outputting the second voltage

[0059] Control the fourth switch tube Q4 to be turned off, and control the second switch tube Q2 and the sixth switch tube Q6 to be turned on, and the output voltage is 0;

[0060] Control the third switch tube Q3 and the fourth switch tube Q4 to be turned off, and control the second switch tube Q2 and the fifth switch tube Q5 to be turned on, to output a fourth voltage -Ui;

[0061] Control the sixth switch tube Q6 to be turned off, and control the third switch tube Q3, the fourth switch tube Q4 and the fifth switch tube Q5 to be turned on, outputting the third voltage

[0062] The third switch tube Q3 is controlled to be turned off, and the first switch tube Q1 and the fifth switch tube Q5 are controlled to be turned on, and the output voltage is 0.

[0063] In the embodiment of the present application, the first switching unit 201 outputs the second target voltage converted by the transformer T through the parasitic diode of the first switch tube Q1 and the parasitic diode of the sixth switch tube Q6.

[0064] In another possible embodiment, Figure 3 As shown, the first switching unit 201 also includes: a first capacitor C1 and a second capacitor C2, wherein: the first capacitor C1 is connected between the second end of the fourth switch tube Q4 and the positive output end of the energy storage system; the second capacitor C2 is connected between the second end of the fourth switch tube Q4 and the negative output end of the energy storage system.

[0065] In a specific embodiment, the first capacitor C1 and the second capacitor C2 are used to stabilize the received first DC voltage and reduce voltage fluctuations caused by interference.

[0066] In one possible implementation, Figure 4As shown, it is a circuit schematic diagram of another bidirectional buck-boost circuit provided in an embodiment of the present application, the second switching unit 202 includes a fourth bridge arm 401, a fifth bridge arm 402 and a sixth bridge arm 403, the fourth bridge arm 401 and the sixth bridge arm 403 are connected in parallel between the positive DC bus and the negative DC bus, one end of the fifth bridge arm 402 is electrically connected to the positive DC bus and the negative DC bus, and the other end of the fifth bridge arm 402 is electrically connected to the midpoint of the fourth bridge arm 401.

[0067] Specifically, the fourth bridge arm 401 includes a seventh switch tube Q7 and an eighth switch tube Q8, the fifth bridge arm 402 includes a ninth switch tube Q9 and a tenth switch tube Q10, and the sixth bridge arm 403 includes an eleventh switch tube Q11 and a twelfth switch tube Q12;

[0068] A first end of the seventh switch tube Q7 is electrically connected to the positive DC bus, a second end of the seventh switch tube Q7 is electrically connected to a first end of the eighth switch tube Q8, a third end of the transformer T, and a first end of the ninth switch tube Q9, and a second end of the eighth switch tube Q8 is electrically connected to the negative DC bus.

[0069] The second end of the ninth switch tube Q9 is electrically connected to the first end of the tenth switch tube Q10, and the second end of the tenth switch tube Q10 is electrically connected to the positive DC bus and the negative DC bus;

[0070] A first end of the eleventh switch tube Q11 is electrically connected to the positive DC bus, a second end of the eleventh switch tube Q11 is electrically connected to a first end of the twelfth switch tube Q12 and the fourth end of the transformer T, and a second end of the twelfth switch tube Q12 is electrically connected to the negative DC bus.

[0071] In the embodiment of the present application, the second switching unit 202 converts the received second DC voltage Ui by controlling the opening and closing of the seventh switch tube Q7, the eighth switch tube Q8, the ninth switch tube Q9, the tenth switch tube Q10, the eleventh switch tube Q11 and the twelfth switch tube Q1, and outputs the fifth voltage Ui and the sixth voltage Ui. Seventh voltage and the eighth voltage -Ui.

[0072] Specifically, the seventh switch tube Q7 and the twelfth switch tube Q12 are controlled to be turned on to output the fifth voltage Ui;

[0073] The seventh switch tube Q7 is turned off, and the ninth switch tube Q9, the tenth switch tube Q10 and the twelfth switch tube Q12 are turned on to output the sixth voltage.

[0074] Control the tenth switch tube Q10 to be turned off, and control the eighth switch tube Q8 and the twelfth switch tube Q12 so that the output voltage is 0;

[0075] Controlling the ninth switch tube Q9 and the tenth switch tube Q10 to be turned off, and controlling the eighth switch tube Q8 and the eleventh switch tube Q11 to be turned on, to output the eighth voltage -Ui;

[0076] The twelfth switch tube Q12 is turned off, and the ninth switch tube Q9, the tenth switch tube Q10 and the eleventh switch tube Q11 are turned on to output the seventh voltage.

[0077] The ninth switch tube Q9 is controlled to be turned off, and the seventh switch tube Q7 and the eleventh switch tube Q11 are controlled to be turned on, and the output voltage is 0.

[0078] In the embodiment of the present application, the second switching unit 202 outputs the first target voltage converted by the transformer T through the parasitic diode of the seventh switch tube Q7 and the parasitic diode of the twelfth switch tube Q12.

[0079] In another possible embodiment, Figure 4 As shown, the second switching unit 202 includes: a third capacitor C3 and a fourth capacitor C4, wherein: the third capacitor C3 is connected between the second end of the tenth switch tube Q10 and the positive DC bus; the fourth capacitor C4 is connected between the second end of the tenth switch tube Q10 and the negative DC bus.

[0080] In a specific embodiment, the third capacitor C3 and the fourth capacitor C4 are used to stabilize the received second DC voltage and reduce voltage fluctuations caused by interference.

[0081] In one embodiment, Figure 5 , which is a schematic diagram of another bidirectional buck-boost circuit provided in an embodiment of the present application, further comprising: a fifth capacitor C5, a sixth capacitor C6, a first inductor L1, and a second inductor L2;

[0082] A first end of the fifth capacitor C5 is electrically connected to the second end of the first switch tube Q1 and the first end of the second switch tube Q2. A second end of the fifth capacitor C5 is electrically connected to the first end of the first inductor L1. A second end of the first inductor L1 is electrically connected to the first end of the transformer T.

[0083] A first end of the sixth capacitor C6 is electrically connected to the third end of the transformer T, a second end of the sixth capacitor C6 is electrically connected to the first end of the second inductor L2, and a second end of the second inductor L2 is electrically connected to the second end of the seventh switch tube Q7 and the first end of the eighth switch tube Q8.

[0084] In a specific embodiment, by adding the fifth capacitor C5 and the first inductor L1 to form an LC resonant circuit, and by adding the sixth capacitor C6 and the second inductor L2 to form an LC resonant circuit, the switching tubes in the first switching unit 201 and the second switching unit 202 can be turned on at zero voltage under the action of LC resonance, thereby reducing switching losses and improving the working efficiency of the circuit.

[0085] Based on the same concept, the embodiment of the present invention also provides a bidirectional buck-boost control method, the implementation of which can refer to the implementation of the above circuit, and the repeated parts will not be repeated. Figure 6 As shown, the method includes:

[0086] S601: Convert a received first DC voltage through a first switching unit, and output a first voltage, a second voltage, a third voltage, and a fourth voltage within a cycle, or output a second target voltage converted by a transformer, wherein the first voltage is the same as the first DC voltage, the fourth voltage is an inverse voltage of the first voltage, the second voltage is less than the first voltage, and the third voltage is an inverse voltage of the second voltage;

[0087] S602: Convert the received first voltage, second voltage, third voltage, and fourth voltage into a first target voltage, or convert the received fifth voltage, sixth voltage, seventh voltage, and eighth voltage into a second target voltage through a transformer;

[0088] S603. Output the first target voltage through the second switching unit, or convert the received second DC voltage to output a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage within one cycle, wherein the fifth voltage is the same as the second DC voltage, the eighth voltage is the inverted voltage of the fifth voltage, the sixth voltage is less than the fifth voltage, and the seventh voltage is the inverted voltage of the sixth voltage.

[0089] An embodiment of the present utility model provides a bidirectional buck-boost circuit and a control method, which converts a first DC voltage into a first voltage, a second voltage, a third voltage and a fourth voltage through a first switching unit, and converts a second DC voltage into a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage through a second switching unit, so as to reduce the voltage ripple of the first target voltage and the second target voltage output by the transformer and reduce EMI problems.

[0090] In a possible implementation, converting the received first DC voltage by the first switching unit to output the first voltage, the second voltage, the third voltage, and the fourth voltage within one cycle includes:

[0091] Controlling the first switch tube and the sixth switch tube to be turned on to output a first voltage;

[0092] Controlling the first switch tube to be turned off, and controlling the third switch tube, the fourth switch tube and the sixth switch tube to be turned on to output a second voltage;

[0093] Controlling the sixth switch tube to be turned off, and controlling the third switch tube, the fourth switch tube, and the fifth switch tube to be turned on to output a third voltage;

[0094] The third switch tube and the fourth switch tube are controlled to be disconnected, and the second switch tube and the fifth switch tube are controlled to be connected to output a fourth voltage.

[0095] It should be noted that the transformer converts the received first voltage, second voltage, third voltage and fourth voltage into the first target voltage.

[0096] The second switching unit outputs the first target voltage converted by the transformer T through the parasitic diode of the seventh switching tube and the parasitic diode of the twelfth switching tube.

[0097] In another possible implementation, converting the received second DC voltage by the second switching unit to output a fifth voltage, a sixth voltage, a seventh voltage, and an eighth voltage within one cycle includes:

[0098] controlling the seventh switch tube and the twelfth switch tube to be turned on to output a fifth voltage;

[0099] controlling the seventh switch tube to be turned off, and controlling the ninth switch tube, the tenth switch tube, and the twelfth switch tube to be turned on, to output a sixth voltage;

[0100] controlling the twelfth switch tube to be turned off, and controlling the ninth switch tube, the tenth switch tube, and the eleventh switch tube to be turned on, to output a seventh voltage;

[0101] The ninth switch tube and the tenth switch tube are controlled to be disconnected, and the eighth switch tube and the eleventh switch tube are controlled to be connected, so as to output an eighth voltage.

[0102] It should be noted that the transformer converts the received fifth voltage, sixth voltage, seventh voltage and eighth voltage into the second target voltage.

[0103] The first switching unit outputs the second target voltage converted by the transformer T through the parasitic diode of the first switching tube and the parasitic diode of the sixth switching tube.

[0104] Based on the same concept, an embodiment of the present invention also provides a bidirectional buck-boost system. The implementation of this system can refer to the implementation of the above-mentioned bidirectional buck-boost circuit and control method, and the repeated parts will not be repeated.

[0105] like Figure 7As shown, it is a structural diagram of a bidirectional buck-boost system provided in an embodiment of the present application, which includes: a bidirectional buck-boost circuit 701, and an energy storage system 702 and a bus capacitor 703 connected to the bidirectional buck-boost circuit 701.

[0106] An embodiment of the present utility model provides a bidirectional buck-boost circuit and system. The present application converts a first DC voltage into a first voltage, a second voltage, a third voltage and a fourth voltage through a first switching unit, and converts a second DC voltage into a fifth voltage, a sixth voltage, a seventh voltage and an eighth voltage through a second switching unit, so as to reduce the voltage ripple of the first target voltage and the second target voltage output by the transformer and reduce EMI problems.

[0107] The present application is described above with reference to block diagrams and / or flow charts illustrating methods, apparatus (systems) and / or computer program products according to embodiments of the present application. It should be understood that a block of a block diagram and / or flow chart, as well as a combination of blocks of a block diagram and / or flow chart, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer and / or other programmable data processing device to produce a machine such that instructions executed by the computer processor and / or other programmable data processing device create a method for implementing the functions / actions specified in the block diagram and / or flow chart block.

[0108] Accordingly, the present application may also be implemented using hardware and / or software (including firmware, resident software, microcode, etc.). Furthermore, the present application may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in conjunction with an instruction execution system. In the context of the present application, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, transmit, or convey a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0109] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A bidirectional buck-boost circuit, characterized in that: include: a first switching unit, a transformer, and a second switching unit; The first switching unit, the transformer and the second switching unit are connected in sequence; The first switching unit is configured to convert the received first DC voltage and output a first voltage, a second voltage, a third voltage, and a fourth voltage within a cycle, or output a second target voltage converted by the transformer, wherein the first voltage is the same as the first DC voltage, the fourth voltage is an inverted voltage of the first voltage, the second voltage is less than the first voltage, and the third voltage is an inverted voltage of the second voltage; The transformer is configured to convert the received first voltage, the second voltage, the third voltage, and the fourth voltage into a first target voltage, or convert the received fifth voltage, the sixth voltage, the seventh voltage, and the eighth voltage into the second target voltage; The second switching unit is used to output the first target voltage, or convert the received second DC voltage, and output the fifth voltage, the sixth voltage, the seventh voltage and the eighth voltage within one cycle, wherein the fifth voltage is the same as the second DC voltage, the eighth voltage is the inverted voltage of the fifth voltage, the sixth voltage is less than the fifth voltage, and the seventh voltage is the inverted voltage of the sixth voltage.

2. The circuit according to claim 1, wherein The first switching unit includes a first bridge arm, a second bridge arm, and a third bridge arm, wherein the first bridge arm includes a first switch tube and a second switch tube, the second bridge arm includes a third switch tube and a fourth switch tube, and the third bridge arm includes a fifth switch tube and a sixth switch tube; The first end of the first switching tube serves as a positive input and output end of the first switching unit, the second end of the first switching tube is electrically connected to the first end of the second switching tube, the first end of the transformer, and the first end of the third switching tube, and the second end of the second switching tube serves as a negative input and output end of the first switching unit; The second end of the third switch tube is electrically connected to the first end of the fourth switch tube, and the second end of the fourth switch tube is connected between the positive input and output ends of the first switching unit and the negative input and output ends of the first switching unit; The first end of the fifth switching tube serves as the positive input and output end of the first switching unit, the second end of the fifth switching tube is electrically connected to the first end of the sixth switching tube and the second end of the transformer, and the second end of the sixth switching tube serves as the negative input and output end of the first switching unit.

3. The circuit according to claim 2, wherein: The first switching unit further includes: a first capacitor and a second capacitor, wherein: The first capacitor is connected between the second end of the fourth switch tube and the positive input and output of the first switching unit; The second capacitor is connected between the second end of the fourth switch tube and the negative input and output of the first switching unit.

4. The circuit according to claim 2, wherein: The second switching unit includes a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm, wherein the fourth bridge arm includes a seventh switch tube and an eighth switch tube, the fifth bridge arm includes a ninth switch tube and a tenth switch tube, and the sixth bridge arm includes an eleventh switch tube and a twelfth switch tube; The first end of the seventh switching tube serves as the positive input and output end of the second switching unit, the second end of the seventh switching tube is electrically connected to the first end of the eighth switching tube, the third end of the transformer, and the first end of the ninth switching tube, and the second end of the eighth switching tube serves as the negative input and output end of the second switching unit; The second end of the ninth switch tube is electrically connected to the first end of the tenth switch tube, and the second end of the tenth switch tube is connected between the positive input and output ends of the second switching unit and the negative input and output ends of the second switching unit; The first end of the eleventh switching tube serves as the positive input and output end of the second switching unit, the second end of the eleventh switching tube is electrically connected to the first end of the twelfth switching tube and the fourth end of the transformer, and the second end of the twelfth switching tube serves as the negative input and output end of the second switching unit.

5. The circuit according to claim 4, wherein The second switching unit includes: a third capacitor and a fourth capacitor, wherein: The third capacitor is connected between the second end of the tenth switch tube and the positive input and output end of the second switching unit; The fourth capacitor is connected between the second end of the tenth switch tube and the negative input and output end of the second switching unit.

6. The circuit according to claim 4, wherein: Also includes: a fifth capacitor, a sixth capacitor, a first inductor, and a second inductor; The first end of the fifth capacitor is electrically connected to the second end of the first switching transistor and the first end of the second switching transistor, the second end of the fifth capacitor is electrically connected to the first end of the first inductor, and the second end of the first inductor is electrically connected to the first end of the transformer; The first end of the sixth capacitor is electrically connected to the third end of the transformer, the second end of the sixth capacitor is electrically connected to the first end of the second inductor, and the second end of the second inductor is electrically connected to the second end of the seventh switching tube and the first end of the eighth switching tube.

7. A bidirectional buck-boost system, characterized in that: The invention comprises the bidirectional buck-boost circuit according to any one of claims 1 to 6, and an energy storage system and a bus capacitor connected to the bidirectional buck-boost circuit.

Images