Three-bridge-arm cascade DC-DC circuit, uninterruptible power supply and circuit board

Abstract

The embodiment of the utility model discloses a three-bridge-arm cascade DC-DC circuit, an uninterruptible power supply and a circuit board. According to the three-bridge-arm cascaded DC-DC circuit and the uninterruptible power supply, the rectification of the secondary side sub-circuit in the DC transformation circuit is realized through the diodes, and the secondary side sub-circuit is connected to the post-stage circuit through the fifth diode, so that the secondary side sub-circuit is not required to be rectified under the application scene that internal charging current is not required or only small charging current is required; multi-power-source direct cascade power supply is achieved through a low-cost circuit, the production cost is reduced, and the product competitiveness is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electronic technology, and in particular to a three-bridge-arm cascade DC-DC circuit, an uninterruptible power supply, and a circuit board. Background Art

[0002] Uninterruptible Power Supply (UPS) is widely used in various situations where high power supply reliability is required. When the mains power is abnormal, the voltage of the UPS battery pack is provided to the DC bus through the boost circuit to ensure the normal DC bus voltage, thereby continuing to power the load.

[0003] To manage the charge and discharge of batteries in a UPS system, some electronic components in the UPS system circuit are designed to be reused. By switching the conduction state of the reused electronic components in the circuit, these reused electronic components can participate in both charging and discharging.

[0004] The inventors analyzed the existing UPS system solutions that reuse some electronic components and found that the UPS system may be used in different application scenarios, each with different performance requirements for the UPS system. The solution of reusing some electronic components has performance redundancy for some UPS systems, and the cost is high when applied to some UPS systems, and the market competitiveness is weak. Utility Model Content

[0005] The utility model provides a three-bridge-arm cascade DC-DC circuit, an uninterruptible power supply and a circuit board to solve the technical problems of high cost and weak market competitiveness when the existing solution of reusing some electronic components is applied to some UPS systems.

[0006] In a first aspect, an embodiment of the present application provides a three-bridge-arm cascade DC-DC circuit, the three-bridge-arm cascade DC-DC circuit comprising: a DC transformer circuit, a switching circuit, and a three-bridge-arm conversion circuit, the switching circuit comprising a first switch and a fifth diode, the secondary sub-circuit of the DC transformer circuit comprising a plurality of diodes for rectification;

[0007] The positive electrode of the first end of the DC conversion circuit is used to connect to the positive electrode of the battery pack, the negative electrode of the first end of the DC conversion circuit is used to connect to the negative electrode of the battery pack, the positive electrode of the second end of the DC conversion circuit is connected to the positive electrode of the fifth diode, and the negative electrode of the fifth diode is connected to the positive voltage input end of the three-arm bridge conversion circuit; the negative electrode of the second end of the DC conversion circuit is connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit; the positive voltage input end is used to connect to the live wire of the AC power supply through the first switch;

[0008] The first switch is used to control the DC transformer circuit to discharge the battery pack in the battery power supply mode.

[0009] As described above, by realizing the rectification of the secondary sub-circuit in the DC transformer circuit through a diode and connecting it to the subsequent circuit through a fifth diode, in application scenarios where no internal charging current is required or only a small charging current is required, direct cascade power supply of multiple power supplies can be realized with a low-cost circuit, thereby reducing production costs and improving product competitiveness.

[0010] The DC voltage conversion circuit includes a transformer, and the secondary sub-circuit includes a first inductor, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a second capacitor;

[0011] The first end of the secondary side of the transformer is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the cathode of the first diode and the anode of the third diode; the cathode of the third diode, the cathode of the fourth diode, and the positive electrode of the second capacitor are all connected to the anode of the fifth diode as the positive electrode of the second end of the DC transformer circuit; the second end of the secondary side of the transformer is connected to the anode of the fourth diode and the negative electrode of the second diode; the anode of the first diode, the positive electrode of the second diode, and the negative electrode of the second capacitor are all connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit as the negative electrode of the second end of the DC transformer circuit.

[0012] As described above, rectification requiring only unidirectional power supply is achieved through multiple diodes, thereby realizing a two-level direct cascade power supply of two power supplies at a low cost.

[0013] The primary sub-circuit of the DC transformer circuit includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0014] The first end of the first switching tube and the first end of the third switching tube are both connected to the positive electrode of the battery pack, the second end of the first switching tube and the first end of the second switching tube are both connected to the first end of the primary side of the transformer, the second end of the second switching tube and the second end of the fourth switching tube are both connected to the negative electrode of the battery pack; the second end of the third switching tube and the first end of the fourth switching tube are both connected to the second end of the primary side of the transformer.

[0015] As described above, the DC transformer circuit implemented by four switching tubes can realize soft switching of the DC transformer circuit, so that the switching tubes in the DC transformer circuit reduce the voltage and current to zero before turning on and off, respectively, and turn on with zero voltage and turn off with zero current, thereby eliminating the overlap of voltage and current of the switching tubes during the switching process, reducing the rate of change, and correspondingly greatly reducing or even eliminating the switching loss of the DC transformer circuit, thereby realizing high frequency of the DC transformer circuit.

[0016] The three-arm conversion circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, an eighth switching tube, a ninth switching tube, a tenth switching tube, a second inductor, a third inductor, a third capacitor and a fourth capacitor;

[0017] The first end of the second inductor is connected to the cathode of the fifth diode as a positive voltage input terminal; the second end of the second inductor is connected to the second end of the fifth switching tube and the first end of the sixth switching tube; the first end of the fifth switching tube is connected to the positive electrode of the fourth capacitor, the first end of the seventh switching tube, and the first end of the ninth switching tube; the second end of the sixth switching tube is connected to the negative electrode of the fourth capacitor, the second end of the eighth switching tube, and the second end of the tenth switching tube, and the negative output terminal of the bus;

[0018] The second end of the ninth switching tube is connected to the first end of the tenth switching tube and the first end of the third inductor; the second end of the third inductor is connected to the first end of the third capacitor; the second end of the seventh switching tube, the first end of the eighth switching tube and the second end of the third capacitor are used to connect to the neutral line of the AC power supply.

[0019] As described above, by connecting the DC transformer circuit in series with the Boost circuit consisting of the second inductor and the first bridge arm of the three-arm conversion circuit, a two-stage boost is achieved, so that the Boost circuit consisting of the second inductor and the first bridge arm of the three-arm conversion circuit can share a portion of the voltage boost operation. This allows a larger boost ratio to be obtained while eliminating the need for the DC transformer circuit itself to perform a boost process with a large voltage difference, thereby improving the reliability of the UPS system with low battery voltage and high current.

[0020] In a second aspect, an embodiment of the present application provides an uninterruptible power supply, which includes any three-bridge-arm cascade DC-DC circuit of the first aspect.

[0021] As described above, the uninterruptible power supply includes the three-bridge-arm cascade DC-DC circuit of the first aspect, and has corresponding beneficial effects.

[0022] In a third aspect, an embodiment of the present application provides a circuit board, which includes any three-bridge-arm cascade DC-DC circuit of the first aspect.

[0023] As described above, the circuit board includes the three-bridge-arm cascade DC-DC circuit of the first aspect, and has corresponding beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a circuit schematic diagram of a three-bridge-arm cascade DC-DC circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended to explain the present invention, not to limit it. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all of its components.

[0026] It should be noted that due to space limitations, this application specification does not enumerate all optional implementation methods. After reading this application specification, those skilled in the art should be able to understand that as long as the technical features do not contradict each other, any combination of technical features can constitute an optional implementation method.

[0027] The following describes in detail the various embodiments of the present invention.

[0028] To manage the charge and discharge of batteries in a UPS system, some electronic components in the UPS system circuit are designed to be reused. By switching the conduction state of the circuit, these reused electronic components can participate in both charging and discharging.

[0029] The inventors analyzed the existing UPS system solutions that reuse some electronic components and found that the UPS system may be used in different application scenarios, and each has different performance requirements for the UPS system. For example, in the application scenario of no current or low current charging, the solution of reusing some electronic components has performance redundancy for some UPS systems, and the cost is high when applied to some UPS systems, and the market competitiveness is weak.

[0030] In response to the above technical problems, the embodiments of the present application propose a three-arm cascade DC-DC circuit, an uninterruptible power supply and a circuit board. The rectification of the secondary sub-circuit in the DC transformer circuit is realized through a diode, and connected to the subsequent circuit through a fifth diode. In application scenarios where no internal charging current is required or only a small charging current is required, direct cascade power supply of multiple power supplies can be achieved with a low-cost circuit, thereby reducing production costs and improving product competitiveness.

[0031] Please refer to Figure 1 , which is a circuit schematic diagram of a three-bridge-arm cascade DC-DC circuit provided by this embodiment, as shown Figure 1As shown, the three-arm cascade DC-DC circuit includes: a DC transformer circuit 10, a switching circuit and a three-arm conversion circuit 20. The switching circuit includes a first switch K1 and a fifth diode D5. The secondary sub-circuit of the DC transformer circuit 10 includes multiple diodes for rectification; the positive electrode of the first end of the DC transformer circuit 10 is used to connect to the positive electrode of the battery pack BAT, the negative electrode of the first end of the DC transformer circuit 10 is used to connect to the negative electrode of the battery pack BAT, the positive electrode of the second end of the DC transformer circuit 10 is connected to the positive electrode of the fifth diode D5, and the negative electrode of the fifth diode D5 is connected to the positive voltage input end of the three-arm conversion circuit 20; the negative electrode of the second end of the DC transformer circuit 10 is connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit; the positive voltage input end is used to connect to the live wire of the AC power supply through the first switch K1; the first switch K1 is used to control the DC transformer circuit 10 to discharge the battery pack BAT in the battery power supply mode.

[0032] The bridge arm is a part of the commutation circuit, which is connected between the AC and DC terminals and has unidirectional or bidirectional conductivity. In the application scenario of realizing AC power supply, a three-bridge-arm conversion circuit is usually composed of three bridge arms as the core, and finally connected to the load to realize power supply. The terminals for realizing power supply are defined as the negative output terminal of the bus and the positive output terminal of the bus. The three bridge arms can be regarded as connected in parallel between the negative output terminal of the bus and the positive output terminal of the bus. Each bridge arm includes two switching tubes connected in series, and the area between the two switching tubes in series is defined as the midpoint of the bridge arm. For the three-bridge-arm conversion circuit, different terminals have corresponding relatively fixed input and output connection definitions. For example, the terminal for connecting to the live wire of the AC power supply is defined as the positive voltage input terminal. In the embodiment of the present application, the connection definition in the three-bridge-arm conversion circuit 20 can refer to the terminal definition of the three-bridge-arm architecture in the relevant technology, which will not be elaborated here.

[0033] Regarding the DC transformer circuit 10, which includes a transformer TX1, with reference to the isolation of the physical connection between the primary and secondary sides of the transformer TX1, the DC transformer circuit 10 is defined as including a primary sub-circuit and a secondary sub-circuit, of which the secondary sub-circuit is relevant to the embodiments of the present application. The primary sub-circuit includes electronic devices directly or indirectly connected to the primary terminals of the DC transformer circuit 10 and their connection relationships; the secondary sub-circuit includes electronic devices directly or indirectly connected to the secondary terminals of the DC transformer circuit 10 and their connection relationships. The secondary sub-circuit includes multiple diodes for rectification, for example, the connection method of the multiple diodes can realize a rectifier bridge that rectifies AC power into DC power.

[0034] In an embodiment of the present application, in response to application scenarios that do not require internal charging current or only require a small charging current, a three-arm cascade DC-DC circuit and an uninterruptible power supply are proposed. The rectification of the secondary sub-circuit in the DC transformer circuit is achieved through a diode, and only the discharge of the battery pack is retained in the internal circuit, and it is connected to the subsequent circuit through the fifth diode, thereby realizing direct cascade power supply of multiple power supplies with a low-cost circuit. Only one switch required for power supply mode switching needs to be retained (i.e., the first switch K1, for example, a relay switch with mature production technology, stable performance, and low cost can be selected), and cheaper electronic components are used at the same time to reduce production costs and improve product competitiveness.

[0035] In an alternative implementation, see Figure 1 The DC transformer circuit 10 includes a transformer TX1, and a secondary sub-circuit includes a first inductor L1, a first capacitor C1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, and a second capacitor C2. The first end of the secondary side of the transformer TX1 is connected to the first end of the first inductor L1, the second end of the first inductor L1 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is connected to the cathode of the first diode D1 and the anode of the third diode D3. The cathode of the third diode D3, the cathode of the fourth diode D4, and the anode of the second capacitor C2 all serve as the anode of the second end of the DC transformer circuit 10 and are connected to the anode of the fifth diode D5. The second end of the secondary side of the transformer TX1 is connected to the anode of the fourth diode D4 and the cathode of the second diode D2. The anode of the first diode D1, the anode of the second diode D2, and the cathode of the second capacitor C2 all serve as the cathode of the second end of the DC transformer circuit 10 and are connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit.

[0036] In this implementation, the second capacitor C2 is connected as a DC bus capacitor between the negative output terminal of the bus and the positive output terminal of the bus, which is equivalent to the second capacitor C2 being connected in parallel with each bridge arm in the three-arm conversion circuit 20. The first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 form a rectifier circuit. The multiple diodes are used to achieve rectification that only requires unidirectional power supply, thereby realizing a two-level direct cascade power supply of two power supplies at a low cost. The first inductor L1 is used as a balancing component to balance the voltage between the BUS of the three-arm conversion circuit and the DC conversion circuit in the mains power supply mode, thereby avoiding the input of a large current to the DC conversion circuit 10 when the fixed end of the first switch K1 is connected to the first selection end of the first switch K1, thereby achieving overcurrent protection for the DC conversion circuit 10.

[0037] In another optional implementation, the primary sub-circuit of the DC transformer circuit 10 includes a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4;

[0038] The first end of the first switching tube Q1 and the first end of the third switching tube Q3 are both connected to the positive electrode of the battery pack BAT, the second end of the first switching tube Q1 and the first end of the second switching tube Q2 are both connected to the first end of the primary side of the transformer TX1, the second end of the second switching tube Q2 and the second end of the fourth switching tube Q4 are both connected to the negative electrode of the battery pack BAT; the second end of the third switching tube Q3 and the first end of the fourth switching tube Q4 are both connected to the second end of the primary side of the transformer TX1.

[0039] In the DC transformer circuit 10, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all triodes, wherein the collector of the triode serves as the corresponding first terminal, the emitter of the triode serves as the corresponding second terminal, and the base of the triode serves as the corresponding control terminal. Alternatively, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all MOS transistors, wherein the drain of the MOS transistor serves as the corresponding first terminal, the source of the MOS transistor serves as the corresponding second terminal, and the gate of the MOS transistor serves as the corresponding control terminal. The first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may also be MOS transistors with parasitic diodes, IGBTs with integrated diodes, etc.

[0040] When using Figure 1 When discharging a battery pack BAT, the illustrated DC transformer circuit 10 uses the first, second, third, and fourth switching transistors Q1, Q2, Q3, and Q4 as switching transistors, and the first, second, third, and fourth diodes D1, D2, D3, and D4 as rectifiers. The first and fourth switching transistors Q1 and Q4 are simultaneously turned on as a group, while the second and third switching transistors Q2 and Q3 are simultaneously turned on as a group. For example, a variable frequency constant duty cycle control method can be used to discharge the battery pack BAT. The term "constant duty cycle" here refers to controlling the first, second, third, and fourth switching transistors Q1, Q2, Q3, and Q4 using the same duty cycle, so that the on-times of the two switching transistor groups are the same. The DC transformer circuit implemented by four switching tubes can realize soft switching of the DC transformer circuit 10, so that the switching tubes in the DC transformer circuit 10 reduce the voltage and current to zero before turning on and off, respectively, and turn on with zero voltage and turn off with zero current, thereby eliminating the overlap of voltage and current of the switching tubes during the switching process, reducing the change rate, and correspondingly greatly reducing or even eliminating the switching loss of the DC transformer circuit 10, thereby realizing high frequency of the DC transformer circuit 10.

[0041] In another optional implementation, the three-arm conversion circuit 20 includes a fifth switch tube Q5, a sixth switch tube Q6, a seventh switch tube Q7, an eighth switch tube Q8, a ninth switch tube Q9, a tenth switch tube Q10, a second inductor L2, a third inductor L3, a third capacitor C3 and a fourth capacitor E1; the first end of the second inductor L2 is connected to the cathode of the fifth diode D5 as a positive voltage input end; the second end of the second inductor L2 is connected to the second end of the fifth switch tube D5 and the first end of the sixth switch tube Q6; the first end of the fifth switch tube Q5 is connected to the positive electrode of the fourth capacitor E1, the third inductor L3 and the fourth capacitor E1; The first end of the seventh switch tube Q7 is connected to the first end of the ninth switch tube Q9; the second end of the sixth switch tube Q6 is connected to the negative electrode of the fourth capacitor E1, the second end of the eighth switch tube Q8, and the second end of the tenth switch tube Q10 are connected to the negative output end of the bus; the second end of the ninth switch tube Q9 is connected to the first end of the tenth switch tube Q10 and the first end of the third inductor L3; the second end of the third inductor L3 is connected to the first end of the third capacitor C3; the second end of the seventh switch tube Q7, the first end of the eighth switch tube Q8, and the second end of the third capacitor C3 are used to connect to the neutral line of the AC power supply.

[0042] In the three-arm conversion circuit 20, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10 are all triodes, with the collector of the triode serving as the corresponding first terminal, the emitter of the triode serving as the corresponding second terminal, and the base of the triode serving as the corresponding control terminal. Alternatively, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10 are all MOS transistors, with the drain of the MOS transistor serving as the corresponding first terminal, the source of the MOS transistor serving as the corresponding second terminal, and the gate of the MOS transistor serving as the corresponding control terminal. The fifth switch Q5, the sixth switch Q6, the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10 may also be MOS transistors with parasitic diodes, IGBTs with integrated diodes, etc.

[0043] In this implementation, the fifth and sixth switching transistors Q5 and Q6 are connected to form a first bridge arm, the seventh and eighth switching transistors Q7 and Q8 form a second bridge arm, and the ninth and tenth switching transistors Q9 and Q10 form a third bridge arm. The connection point between the two switching transistors corresponding to each bridge arm is the midpoint of the bridge arm. The midpoint of the first bridge arm is connected to the second end of the second inductor L2, and the first end of the second inductor L1 serves as the positive voltage input terminal AC_L of the entire three-arm cascade DC-DC circuit. The midpoint of the second bridge arm serves as the negative voltage input terminal AC_N of the three-arm conversion circuit 20. The midpoint of the third bridge arm is connected to the first end of the third inductor L3, and the second end of the third inductor L3 serves as the output terminal of the three-arm cascade DC-DC circuit, which is respectively connected to the load and the first end of the third capacitor C3. The second end of the third capacitor C3 is connected to the negative voltage input terminal AC_N.

[0044] In the mains power supply mode, the first switch K1 can control the mains AC power source AC to power the three-arm conversion circuit 20. At this time, the three-arm conversion circuit converts the AC power input from the mains AC power source AC into DC power (i.e., rectifies the AC power input from the mains AC power source AC). The second capacitor C2 acts as a DC bus capacitor to filter the converted DC power (also known as voltage stabilization) to obtain stable DC power. The three-arm conversion circuit 20 converts the stable DC power into AC power and outputs it to the load to power the load.

[0045] In general, by connecting the DC transformer circuit 10 in series with the Boost circuit composed of the second inductor and the first bridge arm of the three-arm conversion circuit 20, a two-stage boost is achieved, so that the Boost circuit composed of the second inductor C2 and the first bridge arm of the three-arm conversion circuit 20 can share part of the voltage boost operation, thereby obtaining a larger boost ratio while eliminating the need for the DC transformer circuit 10 itself to perform a boost process with a large voltage difference, thereby improving the reliability of the UPS system.

[0046] In mains power mode, the first switch K1 is closed; in battery power mode, the first switch K1 is open. Based on the embodiments of the present application, for the battery pack BAT, the on / off state of the first switch K1 only affects whether the battery pack BAT supplies power to the load. The battery pack BAT itself can be charged using a common charger. For applications that do not require internal charging current or only require a low charging current, there is no need to implement complex and costly internal circuitry to switch between charging and discharging.

[0047] The present application also provides an uninterruptible power supply, which includes the three-bridge-arm cascade DC-DC circuit of any of the above embodiments. The uninterruptible power supply has the same beneficial effects as the three-bridge-arm cascade DC-DC circuit of the above embodiments.

[0048] The present application also provides a circuit board including the three-arm cascaded DC-DC circuit of any of the aforementioned embodiments, which exhibits corresponding beneficial effects. The three-arm cascaded DC-DC circuit can be provided on a single circuit board or on multiple sub-boards, which are combined to implement the circuit functions of the circuit board.

[0049] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0050] Note that the above are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions are readily apparent to those skilled in the art without departing from the scope of protection of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the appended claims.

Claims

1. A three-bridge-arm cascaded DC-DC circuit, characterized in that: include: A DC transformer circuit, a switch circuit, and a three-bridge-arm conversion circuit, wherein the switch circuit includes a first switch and a fifth diode, and the secondary sub-circuit of the DC transformer circuit includes multiple diodes for rectification; The positive electrode of the first end of the DC conversion circuit is used to connect to the positive electrode of the battery pack, the negative electrode of the first end of the DC conversion circuit is used to connect to the negative electrode of the battery pack, the positive electrode of the second end of the DC conversion circuit is connected to the positive electrode of the fifth diode, and the negative electrode of the fifth diode is connected to the positive voltage input end of the three-arm bridge conversion circuit; the negative electrode of the second end of the DC conversion circuit is connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit; the positive voltage input end is used to connect to the live wire of the AC power supply through the first switch; The first switch is used to control the DC transformer circuit to discharge the battery pack in a battery power supply mode.

2. The three-bridge-arm cascade DC-DC circuit according to claim 1, characterized in that: The DC voltage conversion circuit includes a transformer, and the secondary sub-circuit includes a first inductor, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a second capacitor; The first end of the secondary side of the transformer is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the cathode of the first diode and the anode of the third diode; the cathode of the third diode, the cathode of the fourth diode and the positive electrode of the second capacitor are all connected to the anode of the fifth diode as the positive electrode of the second end of the DC transformer circuit; the second end of the secondary side of the transformer is connected to the anode of the fourth diode and the negative electrode of the second diode; the anode of the first diode, the positive electrode of the second diode and the negative electrode of the second capacitor are all connected to the negative output end of the busbar of the three-arm cascade DC-DC circuit as the negative electrode of the second end of the DC transformer circuit.

3. The three-bridge-arm cascade DC-DC circuit according to claim 2, characterized in that: The primary sub-circuit of the DC transformer circuit includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube; The first end of the first switching tube and the first end of the third switching tube are both connected to the positive electrode of the battery pack, the second end of the first switching tube and the first end of the second switching tube are both connected to the first end of the primary side of the transformer, the second end of the second switching tube and the second end of the fourth switching tube are both connected to the negative electrode of the battery pack; the second end of the third switching tube and the first end of the fourth switching tube are both connected to the second end of the primary side of the transformer.

4. The three-bridge-arm cascade DC-DC circuit according to claim 3, characterized in that: The first switching tube, the second switching tube, the third switching tube and the fourth switching tube are all triodes, the collector of the triode serves as the corresponding first end, the emitter of the triode serves as the corresponding second end, and the base of the triode serves as the corresponding control end.

5. The three-bridge-arm cascade DC-DC circuit according to claim 3, characterized in that: The first switching tube, the second switching tube, the third switching tube and the fourth switching tube are all MOS tubes, the drain of the MOS tube serves as the corresponding first end, the source of the MOS tube serves as the corresponding second end, and the gate of the MOS tube serves as the corresponding control end.

6. The three-bridge-arm cascade DC-DC circuit according to any one of claims 1 to 3, characterized in that: The three-bridge-arm conversion circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, an eighth switching tube, a ninth switching tube, a tenth switching tube, a second inductor, a third inductor, a third capacitor and a fourth capacitor; The first end of the second inductor serves as the positive voltage input terminal and is connected to the cathode of the fifth diode; the second end of the second inductor is connected to the second end of the fifth switching transistor and the first end of the sixth switching transistor; the first end of the fifth switching transistor is connected to the positive electrode of the fourth capacitor, the first end of the seventh switching transistor, and the first end of the ninth switching transistor; the second end of the sixth switching transistor is connected to the negative electrode of the fourth capacitor, the second end of the eighth switching transistor, and the second end of the tenth switching transistor, and the negative output terminal of the bus; The second end of the ninth switching tube is connected to the first end of the tenth switching tube and the first end of the third inductor; the second end of the third inductor is connected to the first end of the third capacitor; the second end of the seventh switching tube, the first end of the eighth switching tube and the second end of the third capacitor are used to connect to the neutral line of the AC power supply.

7. The three-bridge-arm cascade DC-DC circuit according to claim 6, characterized in that: The fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube, the ninth switching tube and the tenth switching tube are all triodes, the collector of the triode serves as the corresponding first end, the emitter of the triode serves as the corresponding second end, and the base of the triode serves as the corresponding control end.

8. The three-bridge-arm cascade DC-DC circuit according to claim 6, characterized in that: The fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube, the ninth switching tube and the tenth switching tube are all MOS tubes, the drain of the MOS tube serves as the corresponding first end, the source of the MOS tube serves as the corresponding second end, and the gate of the MOS tube serves as the corresponding control end.

9. Uninterruptible power supply, characterized in that, A three-bridge-arm cascade DC-DC circuit comprising the three-bridge-arm cascade DC-DC circuit according to any one of claims 1 to 8.

10. A circuit board, characterized in that A three-bridge-arm cascade DC-DC circuit comprising the three-bridge-arm cascade DC-DC circuit according to any one of claims 1 to 8.

Images