DC-DC converter, control method, converter and converter controller

Abstract

The invention provides a DC-DC converter, a control method, a converter and a converter controller. The DC-DC converter includes: a capacitor unit provided at a high voltage side and including a first capacitor and a second capacitor connected in series; the switch unit is connected with the capacitor unit in parallel and comprises a plurality of switch tubes which are in cascade connection; the energy storage filter circuit is arranged on the low-voltage side and connected between a first node, located between the adjacent switching tubes in the upper bridge arm, in the multiple switching tubes and a second node, located between the adjacent switching tubes in the lower bridge arm, in the multiple switching tubes, a neutral point between the first capacitor and the second capacitor is connected to a neutral point of the switching unit.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and more specifically, to a DC-DC converter, a control method, a converter and a converter controller. Background Art

[0002] With the continuous advancement of power electronics technology and the growth of application demand, the challenges faced by DC-DC power modules are also gradually increasing. Traditional DC-DC power modules are mainly based on buck (step-down) and boost (step-up) circuit designs in low-voltage environments. These topologies performed well in early application scenarios and were able to effectively meet the needs at the time.

[0003] However, with the continuous improvement of DC bus voltage levels, especially in the development of new energy power generation, electric vehicles, high-voltage DC transmission and other fields, higher requirements are placed on power modules.

[0004] Conventional two-level DC-DC converters have limitations. First, two-level DC-DC converters include power semiconductor devices such as IGBTs (insulated gate bipolar transistors), whose voltage withstand capability directly limits the maximum operating voltage of the system. The rated voltage of the currently widely used IGBT devices usually does not exceed 1050V, which means that even if the circuit design allows for higher input or output voltages, there will be risks in actual operation due to exceeding the safe operating area of ​​the IGBT, which not only limits the voltage range, but also reduces the applicable working conditions of the DC-DC converter.

[0005] Secondly, since each switch element in the two-level structure must withstand the entire DC bus voltage, when the voltage increases, the stress on a single switch also increases. In this case, in order to ensure system safety and reliability, the practical application range of the DC-DC converter will be further reduced. Summary of the invention

[0006] In order to solve at least one of the above technical problems, the present disclosure provides a DC-DC converter.

[0007] One of the purposes of the present disclosure is to provide a DC-DC converter that can be applied to more working conditions.

[0008] According to a first aspect of the present disclosure, a DC-DC converter is provided, the DC-DC converter comprising: a capacitor unit, arranged on a high voltage side and comprising a first capacitor and a second capacitor connected in series; a switch unit, connected in parallel with the capacitor unit and comprising a plurality of switch tubes connected in cascade; an energy storage filter circuit, arranged on a low voltage side and connected between a first node between adjacent switch tubes in an upper bridge arm among the plurality of switch tubes and a second node between adjacent switch tubes in a lower bridge arm among the plurality of switch tubes, wherein a neutral point between the first capacitor and the second capacitor is connected to a neutral point of the switch unit.

[0009] According to a second aspect of the present disclosure, a control method for a DC-DC converter is provided, which may include: determining a duty cycle based on a ratio between a target output voltage of the DC-DC converter and an actual input voltage of the DC-DC converter, and controlling the on and off of multiple switching tubes to charge and discharge a capacitor unit through different charging and discharging circuits based on a size relationship between the duty cycle and a preset value.

[0010] According to a third aspect of the present disclosure, a computer-readable storage medium is provided which stores a program or an instruction, and when the program or the instruction is executed by a processor, the processor is prompted to execute the above control method.

[0011] According to a fourth aspect of the present disclosure, a converter controller is provided, the controller comprising a memory and a processor, the memory storing a program or instruction, and when the program or instruction is executed by the processor, the processor is prompted to execute the above control method.

[0012] According to a fifth aspect of the present disclosure, a converter is provided, the converter comprising the above-mentioned DC-DC converter.

[0013] The DC-DC converter according to the embodiment of the present disclosure can increase the high-voltage side voltage.

[0014] The DC-DC converter according to the embodiment of the present disclosure can reduce ripple current and reduce inductance and capacitance parameters.

[0015] The DC-DC converter according to the embodiment of the present disclosure has a small size, low power consumption and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram showing a current path when the DC-DC converter according to an embodiment of the present disclosure is in a buck mode and the duty cycle is less than a preset value.

[0017] Figure 2 is a schematic diagram showing a current path when the DC-DC converter according to an embodiment of the present disclosure is in a buck mode and the duty cycle is greater than or equal to a preset value.

[0018] Figure 3 is a schematic diagram showing a current path when the DC-DC converter according to an embodiment of the present disclosure is in a boost mode and the duty cycle is less than a preset value.

[0019] Figure 4 is a schematic diagram showing a current path when the DC-DC converter according to an embodiment of the present disclosure is in a boost mode and the duty cycle is greater than or equal to a preset value.

[0020] Figure 5 A topology structure of a DC-DC converter according to an embodiment of the present disclosure is shown.

[0021] Figure 6 is a flowchart illustrating a control method of a DC-DC converter according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] The following detailed description is provided to help gain a comprehensive understanding of the methods, devices and / or systems described herein. However, the order of operations described herein is only an example and is not limited to those orders set forth herein, but may be equivalently replaced or changed except for operations that must occur or be performed in a specific order. In addition, for greater clarity and simplicity, the description of content known in the art will be omitted or simplified.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which the present disclosure belongs after understanding the present disclosure. Unless explicitly defined as such herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal manner.

[0024] Without special instructions, the same reference numerals generally refer to the same elements (e.g., components, steps, and methods). Reference numerals described in previous embodiments may be omitted if they appear again in later embodiments. In addition, the technical features described in different or the same embodiments may be combined in any manner, as long as the combined embodiments or technical solutions are complete and can solve the technical problems of the present application or achieve the technical effects described or not described in the present disclosure but can be determined based on the above complete technical solutions. The terms used in the present disclosure are explained below.

[0025] DC-DC converter: also known as a DC-DC converter, is a power electronic device used to convert a fixed DC voltage level to another different (higher or lower) DC voltage level. The DC-DC converter disclosed in the present invention is suitable for various application scenarios requiring a DC power supply (for example, wind power converter (for example, DC wind power converter), energy storage converter, high-voltage DC transmission system, etc.).

[0026] The DC-DC converter of the present disclosure may include a capacitor unit, a switch unit and an energy storage filter circuit, wherein the capacitor unit is arranged on the high voltage side and includes a first capacitor and a second capacitor connected in series, the switch unit is connected in parallel with the capacitor unit and includes a plurality of switch tubes connected in cascade, the energy storage filter circuit is arranged on the low voltage side and connected between a first node (such as the first node A described below) between adjacent switch tubes in the upper bridge arm among the plurality of switch tubes and a second node (such as the second node B described below) between adjacent switch tubes in the lower bridge arm among the plurality of switch tubes, wherein each of the first capacitor and the second capacitor may include a single capacitor or may include a plurality of capacitors. The neutral point between the first capacitor and the second capacitor is connected to the neutral point of the switch unit. The DC-DC converter of the present disclosure may be a multi-level DC-DC converter (for example, a three-level DC-DC converter), which is described in detail below in conjunction with the accompanying drawings of the present disclosure.

[0027] Figure 1 is a schematic diagram showing a current path when a DC-DC converter according to an embodiment of the present disclosure is in a buck mode and the duty cycle is less than a preset value, Figure 2 is a schematic diagram showing a current path when a DC-DC converter according to an embodiment of the present disclosure is in a buck mode and a duty cycle is greater than or equal to a preset value, Figure 3 is a schematic diagram showing a current path when a DC-DC converter according to an embodiment of the present disclosure is in a boost mode and the duty cycle is less than a preset value, Figure 4 is a schematic diagram showing a current path when the DC-DC converter according to an embodiment of the present disclosure is in a boost mode and the duty cycle is greater than or equal to a preset value.

[0028] Reference Figures 1 to 4The DC-DC converter of the present invention includes a plurality of cascaded switch tubes, and the energy storage filter circuit of the present invention may include a first inductor L1 and a third capacitor C3, and the first inductor L1 and the third capacitor C3 are connected in series between a first node A and a second node B. The first node A may be a node between two adjacent switch tubes in the upper bridge arm, and the second node B may be a node between two adjacent switch tubes in the lower bridge arm. The energy storage filter circuit of the DC-DC converter of the present invention has a simple structure, and the entire DC-DC converter has a small size, low power consumption and high efficiency. The structure of the energy storage filter circuit is not limited to the above structure, and the energy storage filter circuit may be constructed by other circuits including inductors and capacitors, and may also include a switching element (e.g., an IGBT).

[0029] Reference Figures 1 to 4 , the multiple switch tubes disclosed in the present invention may include a first switch tube VT1, a second switch tube VT2, a third switch tube VT3 and a fourth switch tube VT4. Each switch tube can be implemented by a power transistor (for example, IGBT, MOSFET, etc.), and each switch tube includes a power transistor and a diode connected in anti-parallel with the power transistor, where the diode can also be regarded as a diode integrated in the power transistor itself. However, the present disclosure is not limited to this, and the multiple switch tubes disclosed in the present disclosure may include two switch tubes, six switch tubes, eight switch tubes, etc., and the number of the multiple switch tubes disclosed in the present disclosure may be 2N, where N is a positive integer.

[0030] The first switch tube VT1 and the second switch tube VT2 can be arranged in the upper bridge arm and constitute adjacent switch tubes of the upper bridge arm, the third switch tube VT3 and the fourth switch tube VT4 can be arranged in the lower bridge arm and constitute adjacent switch tubes of the lower bridge arm, and the neutral point between the first capacitor C1 and the second capacitor C2 can be connected to the neutral point between the second switch tube VT2 and the third switch tube VT3.

[0031] In one example, the number of switch tubes in the upper bridge arm may be 2M, where M is a positive integer, and the number of switch tubes in the lower bridge arm may also be 2M, where M is a positive integer, and the number of switch tubes in the upper and lower bridge arms may be the same. The first node A may be located at a position that evenly divides the number of switch tubes in the upper bridge arm, and the second node B may be located at a position that evenly divides the number of switch tubes in the lower bridge arm, and the energy storage filter circuit may be connected across the upper and lower bridge arms.

[0032] The DC-DC converter disclosed in the present invention may be a bidirectional DC-DC converter, wherein the high voltage side (having a high voltage VH) may be an output side, and the low voltage side (having a low voltage VL) may be an input side, forming a boost circuit. The high voltage side (having a high voltage VH) may be an input side, and the low voltage side (having a low voltage VL) may be an output side, forming a buck circuit.

[0033] A single control cycle of the DC-DC converter disclosed in the present invention includes four control time periods (respectively, a first time period (t0-t1 time period), a second time period (t1 to t2 time period), a third time period (t2-t3 time period) and a fourth time period (t3-t4 time period)), and these four control time periods are four consecutive time periods.

[0034] Reference Figure 1 In the buck mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the first time period (t0-t1 time period), the power transistor in the first switch tube VT1 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. The on-off mode of the power transistors in the switch tubes can be high-level on and low-level off, that is, a high-level control signal can be provided to the power transistor of the first switch tube VT1 to turn it on, and a low-level control signal can be provided to the second switch tube VT2, the third switch tube VT3 and the fourth switch tube VT4 to turn them off. However, this is only an example, and the on-off mode of the switch tube is not limited to this. Through the above control method, a current path can be formed, which is the positive end of the first capacitor C1 → the power transistor in the first switch tube VT1 → the first inductor L1 → the third capacitor C3 → the diode in the third switch tube VT3 → the negative end of the first capacitor C1. At this time, the first capacitor C1 is discharged, the current of the first inductor L1 increases, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL. The voltage between the input end and the output end can be VH / 2.

[0035] As an example, in the buck mode, the duty cycle of the switch control signal can be calculated based on the ratio between the desired output voltage and the input voltage, and the relationship between the high-voltage side voltage VH, the low-voltage side voltage VL and the duty cycle D can satisfy VH×D=VL. For example, when the input voltage on the high-voltage side is 2000V and the desired output voltage is 400V, the duty cycle of the switch control signal is 0.4, that is, the duty cycle is less than the preset value of 0.5, so the above control method can be adopted.

[0036] Reference Figure 1In the buck mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the second time period (t1-t2 time period), the power transistor in each switch tube can be controlled to be turned off, and at this time, the diodes in the second switch tube VT2 and the third switch tube VT3 are turned on. Through the above control method, a current path of the first node A→the first inductor L1→the third capacitor C3→the second node B→the diode in the third switch tube VT3→the diode in the second switch tube VT2 can be formed. At this time, the current of the first inductor L1 increases, the first capacitor C1 discharges, the current of the first inductor L1 decreases, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end (the voltage VAB between the AB ports described below) can be zero.

[0037] Reference Figure 1 In the buck mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the third time period (t2-t3 time period), the power transistor in the fourth switch tube VT4 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the second switch tube VT2 is turned on. Through the above control method, a current path of the positive end of the second capacitor C2 → the diode in the second switch tube VT2 → the first inductor L1 → the third capacitor C3 → the power transistor in the fourth switch tube VT4 → the negative end of the first capacitor C1 can be formed. At this time, the second capacitor C2 is discharged, the current of the first inductor L1 increases, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL. The voltage between the input end and the output end can be VH / 2.

[0038] Reference Figure 1 In the buck mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the fourth time period (t3-t4 time period), the power transistor in each switch tube can be controlled to be turned off, and at this time, the diodes in the second switch tube VT2 and the third switch tube VT3 are turned on. Through the above control method, a current path of the first node A→the first inductor L1→the third capacitor C3→the second node→the diode in the third switch tube VT3→the diode in the second switch tube VT2 can be formed, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end can be zero.

[0039] In the step-down mode and when the duty cycle is less than a preset value, the output voltage of the DC-DC converter can vary between VH / 2 and 0.

[0040] Reference Figure 2In the buck mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the first time period (t0-t1 time period), the power transistors in the first switch tube VT1 and the fourth switch tube VT4 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. Through the above control method, a current path of the positive end of the first capacitor C1 → the power transistor in the first switch tube VT1 → the first inductor L1 → the third capacitor C3 → the power transistor in the fourth switch tube VT4 → the negative end of the second capacitor C2 can be formed. At this time, the first capacitor C1 and the second capacitor C2 are discharged, the current of the first inductor L1 increases, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end can be VH.

[0041] Reference Figure 2 In the buck mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the second time period (t1-t2 time period), the power transistor in the first switch tube VT1 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the third switch tube VT3 is turned on. Through the above control method, a current path of the positive end of the first capacitor C1 → the power transistor in the first switch tube VT1 → the first inductor L1 → the third capacitor C3 → the diode in the third switch tube VT3 → the negative end of the first capacitor C1 can be formed. At this time, the current of the first inductor L1 decreases, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end can be VH / 2.

[0042] Reference Figure 2 In the buck mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the third time period (t2-t3 time period), the power transistor in the first switch tube VT1 can be controlled to be turned on, and the power transistor in the fourth switch tube VT4 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. Through the above control method, a current path of the positive end of the first capacitor C1 → the power transistor in the first switch tube VT1 → the first inductor L1 → the third capacitor C3 → the power transistor in the fourth switch tube VT4 → the negative end of the second capacitor C2 can be formed, the current of the first inductor L1 is reduced, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end can be VH.

[0043] Reference Figure 2In the buck mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the fourth time period (t3-t4 time period), the power transistor in the fourth switch tube VT4 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the second switch tube VT2 is turned on. Through the above control method, a current path of the positive end of the second capacitor C2 → the diode in the second switch tube VT2 → the first inductor L1 → the third capacitor C3 → the power transistor in the fourth switch tube VT4 → the negative end of the second capacitor C2 can be formed, the current of the first inductor L1 is reduced, and the third capacitor C3 of the energy storage filter circuit can output a low voltage VL, and the voltage between the input end and the output end can be VH / 2.

[0044] In the boost mode, the duty cycle of the switch control signal can be calculated based on the ratio of the difference between the desired output voltage and the input voltage to the desired output voltage. For example, the relationship between the high-voltage side voltage VH, the low-voltage side voltage VL and the duty cycle D can satisfy VH=VL / (1-D). For example, when the input voltage on the high-voltage side is 400V and the desired output voltage is 2000V, the duty cycle of the switch control signal is 0.8, that is, the duty cycle is greater than the preset value of 0.5. When the input voltage on the high-voltage side is 1600V and the desired output voltage is 2000V, the duty cycle of the switch control signal is 0.2, that is, the duty cycle is less than the preset value of 0.5.

[0045] Reference Figure 3 In the boost mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the first time period (t0-t1 time period), the power transistor in the second switch tube VT2 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off, and the diode in the fourth switch tube VT4 can be turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the power transistor in the second switch tube VT2 → the second capacitor C2 → the diode in the fourth switch tube VT4 → the negative end of the third capacitor C3 can be formed. The second capacitor C2 is charged, the current of the first inductor L1 increases, and the voltage between the input end and the output end can be VH / 2.

[0046] Reference Figure 3In the boost mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the second time period (t1-t2 time period), the power transistor in each switch tube can be controlled to be turned off, and at this time, the diodes in the first switch tube VT1 and the fourth switch tube VT4 are turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the diode in the first switch tube VT1 → the first capacitor C1 → the second capacitor C2 → the diode in the fourth switch tube VT4 → the negative end of the third capacitor C3 can be formed. At this time, the current of the first inductor L1 decreases. The voltage between the input terminal and the output terminal can be VH.

[0047] Reference Figure 3 In the boost mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the third time period (t2-t3 time period), the power transistor in the third switch tube can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the first switch tube VT1 is turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the diode in the first switch tube VT1 → the first capacitor C1 → the power transistor in the third switch tube VT3 → the negative end of the third capacitor C3 can be formed. In this process, the current of the first inductor L1 decreases, and the first capacitor C1 is charged.

[0048] Reference Figure 3 In the boost mode, when the duty cycle D of the switch control signal is less than a preset value (for example, 0.5), in the fourth time period (t3-t4 time period), the power transistor in each switch tube can be controlled to be turned off, and at this time, the diodes in the first switch tube VT1 and the fourth switch tube VT4 are turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the diode in the first switch tube VT1 → the first capacitor C1 → the second capacitor C2 → the diode in the fourth switch tube VT4 → the negative end of the third capacitor C3 can be formed. At this time, the current of the first inductor L1 decreases, and the voltage between the input end and the output end can be VH.

[0049] Reference Figure 4In the boost mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the first time period (t0-t1 time period), the power transistors in the second switch tube VT2 and the third switch tube VT3 can be controlled to be turned on, and the power transistors in the first switch tube VT1 and the fourth switch tube VT4 can be controlled to be turned off. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the power transistor in the second switch tube VT2 → the power transistor in the third switch tube VT3 can be formed. In this process, the current of the first inductor L1 increases, and the voltage between the input end and the output end can be zero.

[0050] Reference Figure 4 In the boost mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the second time period (t1-t2 time period), the power transistor in the second switch tube VT2 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the fourth switch tube VT4 is turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the power transistor in the second switch tube VT2 → the second capacitor C2 → the diode in the fourth switch tube VT4 → the negative end of the third capacitor C3 can be formed. In this process, the current of the first inductor L1 decreases, and the voltage between the input end and the output end can be VH / 2.

[0051] Reference Figure 4 In the boost mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the third time period (t2-t3 time period), the power transistors in the second switch tube VT2 and the third switch tube VT3 can be controlled to be turned on, and the power transistors in the first switch tube VT1 and the fourth switch tube VT4 can be controlled to be turned off. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the power transistor in the second switch tube VT2 → the power transistor in the third switch tube VT3 → the negative end of the third capacitor C3 can be formed. In this process, the current of the first inductor L1 increases, and the voltage between the input end and the output end can be zero.

[0052] Reference Figure 4In boost mode, when the duty cycle D of the switch control signal is greater than or equal to a preset value (for example, 0.5), in the fourth time period (t3-t4 time period), the power transistor in the third switch tube VT3 can be controlled to be turned on, and the power transistors in other switch tubes can be controlled to be turned off. At this time, the diode in the first switch tube VT1 is turned on. Through the above control method, a current path of the positive end of the third capacitor C3 → the first inductor L1 → the diode in the first switch tube VT1 → the first capacitor C1 → the power transistor in the third switch tube VT3 → the negative end of the third capacitor C3 can be formed. In this process, the current of the first inductor L1 decreases, and the voltage between the input end and the output end can be VH / 2. Refer to Figure 4 , the output voltage of the DC-DC converter can vary between VH / 2 and VH.

[0053] The above describes the current path when the DC-DC converter of the present disclosure includes four switching tubes. When it includes six switching tubes or more, the charging and discharging sequence and the on-off mode of each capacitor in the capacitor unit are similar and will not be repeated here.

[0054] Figure 5 A topology structure of a DC-DC converter according to an embodiment of the present disclosure is shown.

[0055] As mentioned above, the DC-DC converter of the present disclosure is a bidirectional DC-DC converter. Figure 5 , one end (A+) and the other end (A-) of the capacitor unit are respectively connected to the positive DC bus and the negative DC bus in the DC bus, and the voltage of the DC bus can be greater than or equal to 2100V. For example, the voltage at one end of the capacitor unit can be +1050V, the voltage at the other end of the capacitor unit can be -1050V, and the voltage at the neutral point is 0V. The two ends of the third capacitor C3 can be respectively connected to the first low-voltage port (B+) and the second low-voltage port (B-). When the current flows from left to right, the DC-DC converter operates in the buck mode, and when the current flows from right to left, the DC-DC converter operates in the boost mode.

[0056] Reference Figure 5 The high voltage side may also include a transformer T1 and a relay K1, and the relay K1 may be located on the positive branch. In addition, the low voltage side may also include a relay K2, and the relay K2 may be located on the positive branch. Although not shown, the energy storage filter circuit described above is also included between the first node A and the second node B.

[0057] Reference Figure 5The DC-DC converter of the present disclosure may include three groups of switch units, and each group of switch units may have the same structure. However, the present disclosure is not limited thereto. The DC-DC converter of the present disclosure may include two or more groups of switch units. When multiple groups of switch units are included, a staggered multi-branch may be formed, thereby reducing ripple current, inductance, and capacitance parameters.

[0058] Figure 6 is a flowchart illustrating a control method of a DC-DC converter according to an embodiment of the present disclosure.

[0059] Reference Figure 6 , the control method of the DC-DC converter according to the first embodiment of the present disclosure may include step S610 and step S620.

[0060] In step S610, the duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter. According to the working conditions applied by the DC-DC converter, the DC-DC converter can output an output voltage of up to 2100V when including four switch tubes, however, this is only an example, and the target output voltage can vary within a certain range.

[0061] In step S620, based on the magnitude relationship between the duty cycle and the preset value, the on and off of the plurality of switch tubes are controlled to charge and discharge the capacitor unit through different charge and discharge loops.

[0062] The duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter. According to the size relationship between the duty cycle and the preset value, the step of controlling the on and off of multiple switch tubes to charge and discharge the capacitor unit through different charging and discharging loops may include responding to the DC-DC converter being in the buck mode and the duty cycle being less than the preset value (for example, 0.5), and the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows.

[0063] In the first time period (t0-t1 time period), the power transistor in the switch tube located between one end of the switch unit and the first node in the upper bridge arm is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off. At this time, the diode in the switch tube located between the neutral point of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor of the first switch tube V1 is turned on, and the diode in the third switch tube VT3 is turned on.

[0064] In the second time period (t1-t2 time period), the power transistors in the plurality of switch tubes are turned off based on the determined duty cycle, and the diodes in the switch tubes between the first node and the second node are turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diodes in the second switch tube V2 and the third switch tube are turned on.

[0065] In the third time period (t2-t3 time period), the power transistor in the switch tube located between the other end of the switch unit and the second node in the lower bridge arm is controlled to be turned on based on the determined duty cycle, and the power transistors in other switch tubes are controlled to be turned off, and the diode in the switch tube located between the first node and the neutral point of the switch unit in the upper bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the second switch tube V2 and the power transistor in the fourth switch tube VT4 are turned on.

[0066] In the fourth time period (t3-t4 time period), the power transistors in the plurality of switch tubes are turned off based on the determined duty cycle, and the diodes in the switch tubes between the first node and the second node are turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diodes in the second switch tube V2 and the diodes in the third switch tube VT3 are turned on.

[0067] As an example, the duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter. According to the size relationship between the duty cycle and the preset value, the step of controlling the on and off of multiple switching tubes to charge and discharge the capacitor unit through different charging and discharging loops also includes: in response to the DC-DC converter being in the buck mode and the duty cycle being greater than or equal to the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows.

[0068] In the first time period, based on the determined duty cycle, the power transistor in the switch tube located between one end of the switch unit and the first node in the upper bridge arm is turned on, and the power transistor in the switch tube located between the second node and the other end of the switch unit in the lower bridge arm is turned on, and the power transistors in other switch tubes are turned off. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the first switch tube V1 and the power transistor in the fourth switch tube VT4 are turned on.

[0069] In the second time period, based on the determined duty cycle, the power transistor in the switch tube located between one end of the switch unit and the first node in the upper bridge arm is turned on and the power transistors in other switch tubes are turned off, and the diode in the switch tube located between the neutral point of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the first switch tube V1 and the diode in the third switch tube VT3 are turned on.

[0070] In the third time period, based on the determined duty cycle, the power transistor in the switch tube located between one end of the switch unit and the first node in the upper bridge arm is turned on, and the power transistor in the switch tube located between the second node and the other end of the switch unit in the lower bridge arm is turned on, and the power transistors in other switch tubes are turned off. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the first switch tube V1 and the power transistor in the fourth switch tube VT4 are turned on.

[0071] In the fourth time period, the power transistor in the switch tube located between the other end of the switch unit and the second node in the lower bridge arm is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off, and the diode in the switch tube located between the first node and the neutral point of the switch unit in the upper bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the second switch tube V2 and the power transistor in the fourth switch tube VT4 are turned on.

[0072] As an example, the duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter. According to the size relationship between the duty cycle and the preset value, the step of controlling the on and off of multiple switching tubes to charge and discharge the capacitor unit through different charging and discharging loops may also include: in response to the DC-DC converter being in the boost mode and the duty cycle being less than the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows.

[0073] In the first time period, based on the determined duty cycle, the power transistor in the switch tube located between the first node and the neutral point of the switch unit in the upper bridge arm is turned on, the power transistors in the other switch tubes are turned off, and the diode in the switch tube located between the other end of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the second switch tube V2 and the diode in the fourth switch tube VT4 are turned on.

[0074] In the second time period, the power transistor in each switch tube is controlled to be turned off based on the determined duty cycle, the diode in the switch tube between one end of the switch unit and the first node in the upper bridge arm is turned on, and the diode in the switch tube between the other end of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the first switch tube V1 and the diode in the fourth switch tube VT4 are turned on.

[0075] In the third time period, the power transistor in the switch tube located between the neutral point and the second node of the switch unit in the lower bridge arm is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off, and the diode in the switch tube located between the first node and one end of the switch unit in the upper bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the first switch tube V1 and the power transistor in the third switch tube VT3 are turned on.

[0076] In the fourth time period, the power transistor in each switch tube is controlled to be turned off based on the determined duty cycle, the diode in the switch tube between one end of the switch unit and the first node in the upper bridge arm is turned on, and the diode in the switch tube between the other end of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the first switch tube V1 and the diode in the fourth switch tube VT4 are turned on.

[0077] As an example, the duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter, and according to the size relationship between the duty cycle and the preset value, the step of controlling the on and off of multiple switching tubes to charge and discharge the capacitor unit through different charging and discharging loops also includes: in response to the DC-DC converter being in the boost mode and the duty cycle being greater than or equal to the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows.

[0078] In the first time period, the power transistor in the switch tube between the first node and the second node is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the second switch tube V2 and the power transistor in the third switch tube VT3 are turned on.

[0079] In the second time period, based on the determined duty cycle, the power transistor in the switch tube located between the first node and the neutral point of the switch unit in the upper bridge arm is turned on and the power transistors in other switch tubes are turned off, and the diode in the switch tube located between the other end of the switch unit and the second node in the lower bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the second switch tube V2 and the diode in the fourth switch tube VT4 are turned on.

[0080] In the third time period, the power transistor in the switch tube between the first node and the second node is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off. As described above, taking the switch unit including four cascaded switch tubes as an example, the power transistor in the second switch tube V2 and the power transistor in the third switch tube VT3 are turned on.

[0081] In the fourth time period, the power transistor in the switch tube located between the neutral point of the switch unit and the second node in the lower bridge arm is turned on based on the determined duty cycle, and the power transistors in other switch tubes are turned off, and the diode in the switch tube located between one end of the switch unit and the first node in the upper bridge arm is turned on. As described above, taking the switch unit including four cascaded switch tubes as an example, the diode in the first switch tube V1 and the power transistor in the third switch tube VT3 are turned on.

[0082] As described above, the preset value of the present disclosure may be 0.5, however, this is only an example, and the preset value of the present disclosure may be 0.4, 0.6, etc. As an example, when the DC-DC converter of the present disclosure is a five-level DC-DC converter, the preset value may take other values ​​(e.g., 0.6, 0.7, etc.) besides 0.5.

[0083] Each step of the above control method can be implemented by a corresponding software or hardware module or unit.

[0084] The above has been referred to Figures 1 to 6 A DC-DC converter and a control method thereof according to an exemplary embodiment of the present disclosure are described. However, it should be understood that the units, modules, and systems shown in the accompanying drawings may be configured to perform software, hardware, firmware, or any combination of the above items for specific functions. For example, these systems and devices may correspond to dedicated integrated circuits, pure software codes, or modules combining software and hardware. In addition, one or more functions implemented by these systems or devices may also be uniformly executed by components in physical entity devices (e.g., processors, clients, or servers, etc.).

[0085] For example, according to an exemplary embodiment of the present disclosure, a computer-readable storage medium storing instructions may be provided, wherein when the instructions are executed by at least one computing device, the at least one computing device is prompted to perform at least one of the above steps.

[0086] It should be noted that the control method according to the exemplary embodiment of the present disclosure may rely on the execution of a computer program or instructions to implement the corresponding functions, that is, each device corresponds to each step in the functional architecture of the computer program, so that the entire system is called through a special software package (e.g., lib library) to implement the corresponding functions.

[0087] On the other hand, when the system, unit, or module is implemented in software, firmware, middleware, or microcode, the program code or code segment for performing the corresponding operation may be stored in a computer-readable medium such as a storage medium, so that at least one processor or at least one computing device may perform the corresponding operation by reading and running the corresponding program code or code segment. In addition, the computer-readable medium or storage medium may cause the processor to execute the above-mentioned control method when the computer program is executed by the processor.

[0088] For example, according to an exemplary embodiment of the present disclosure, a computer device including a readable medium storing computer program instructions may be provided, wherein the instructions, when executed by at least one computing device, prompt the at least one computing device to perform at least one of the above steps.

[0089] The computer-readable storage medium according to an embodiment of the present disclosure stores a program or an instruction, and when the program or the instruction is executed by a processor, the processor is prompted to execute the control method as described above.

[0090] According to an embodiment of the present disclosure, the converter controller may include a memory and a processor, wherein the memory stores a program or an instruction, and when the program or the instruction is executed by the processor, the processor is prompted to execute the above control method.

[0091] The converter according to the embodiments of the present disclosure may include a DC-DC converter and / or a converter controller.

[0092] The DC-DC converter according to the embodiments of the present disclosure can be applied to more working conditions.

[0093] The DC-DC converter according to the embodiment of the present disclosure can obtain a higher DC bus voltage.

[0094] While exemplary embodiments have been shown and described above, it will be readily apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A DC-DC converter, characterized in that: The DC-DC converter comprises: A capacitor unit, arranged at the high voltage side and comprising a first capacitor and a second capacitor connected in series; A switch unit, connected in parallel with the capacitor unit and comprising a plurality of switch tubes connected in cascade; The energy storage filter circuit is arranged at the low voltage side and connected between a first node between adjacent switch tubes in the upper bridge arm among the plurality of switch tubes and a second node between adjacent switch tubes in the lower bridge arm among the plurality of switch tubes. Wherein, the neutral point between the first capacitor and the second capacitor is connected to the neutral point of the switch unit.

2. The DC-DC converter according to claim 1, characterized in that: The energy storage filter circuit includes a first inductor and a third capacitor, and the first inductor and the third capacitor are connected in series between the first node and the second node.

3. The DC-DC converter according to claim 1, characterized in that: The multiple switching tubes include a first switching tube, a second switching tube, a third switching tube and a fourth switching tube. The first switching tube and the second switching tube are arranged in the upper bridge arm and constitute the adjacent switching tubes of the upper bridge arm. The third switching tube and the fourth switching tube are arranged in the lower bridge arm and constitute the adjacent switching tubes of the lower bridge arm. The neutral point between the first capacitor and the second capacitor is connected to the neutral point between the second switching tube and the third switching tube.

4. The DC-DC converter according to claim 2, characterized in that: The DC-DC converter is a bidirectional DC-DC converter, and the two ends of the third capacitor are respectively connected to the first low-voltage port and the second low-voltage port, and one end and the other end of the capacitor unit are respectively connected to the positive DC bus and the negative DC bus in the DC bus.

5. The DC-DC converter according to claim 4, characterized in that: The voltage of the DC bus is greater than or equal to 2100V, and the multiple switch tubes include a power transistor and a diode anti-parallel to the power transistor.

6. A control method for a DC-DC converter, characterized in that: The DC-DC converter is a DC-DC converter according to any one of claims 1 to 5, and the control method comprises: The duty cycle is determined according to the ratio between the target output voltage of the DC-DC converter and the actual input voltage of the DC-DC converter, and according to the size relationship between the duty cycle and a preset value, the on and off of the multiple switching tubes are controlled to charge and discharge the capacitor unit through different charging and discharging circuits.

7. The control method of the DC-DC converter according to claim 6, characterized in that: The step of determining a duty cycle according to a ratio between a target output voltage of the DC-DC converter and an actual input voltage of the DC-DC converter, and controlling the on and off of the plurality of switch tubes to charge and discharge the capacitor unit through different charge and discharge loops according to a magnitude relationship between the duty cycle and a preset value comprises: In response to the DC-DC converter being in the buck mode and the duty cycle being less than the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows: In a first time period, based on the duty cycle, a power transistor in a switch tube located between one end of the switch unit and the first node in the upper bridge arm is controlled to be turned on and power transistors in other switch tubes are controlled to be turned off, and a diode in a switch tube located between a neutral point of the switch unit and the second node in the lower bridge arm is turned on; In a second time period, based on the duty cycle, the power transistors in the plurality of switch tubes are controlled to be turned off, and the diode in the switch tube between the first node and the second node is turned on; In a third time period, based on the duty cycle, a power transistor in the switch tube in the lower bridge arm located between the other end of the switch unit and the second node is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off, and a diode in the switch tube in the upper bridge arm located between the first node and the neutral point of the switch unit is turned on; In a fourth time period, the power transistors in the plurality of switch tubes are controlled to be turned off based on the duty cycle, and the diode in the switch tube between the first node and the second node is turned on.

8. The control method of the DC-DC converter according to claim 7, characterized in that: The step of determining a duty cycle according to a ratio between a target output voltage of the DC-DC converter and an actual input voltage of the DC-DC converter, and controlling the on and off of the plurality of switch tubes to charge and discharge the capacitor unit through different charge and discharge circuits according to a magnitude relationship between the duty cycle and a preset value further includes: In response to the DC-DC converter being in the buck mode and the duty cycle being greater than or equal to the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows: In a first time period, based on the duty cycle, a power transistor in a switch tube located between one end of the switch unit and the first node in the upper bridge arm is controlled to be turned on, a power transistor in a switch tube located between the second node and the other end of the switch unit in the lower bridge arm is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off; In a second time period, based on the duty cycle, a power transistor in a switch tube located between one end of the switch unit and the first node in the upper bridge arm is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off, and a diode in a switch tube located between a neutral point of the switch unit and the second node in the lower bridge arm is turned on; In a third time period, based on the duty cycle, a power transistor in a switch tube located between one end of the switch unit and the first node in the upper bridge arm is controlled to be turned on, a power transistor in a switch tube located between the second node and the other end of the switch unit in the lower bridge arm is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off; In the fourth time period, the power transistor in the switch tube in the lower bridge arm located between the other end of the switch unit and the second node is turned on based on the duty cycle, and the power transistors in other switch tubes are turned off, and the diode in the switch tube in the upper bridge arm located between the first node and the neutral point of the switch unit is turned on.

9. The control method of the DC-DC converter according to claim 7, characterized in that: The step of determining a duty cycle according to a ratio between a target output voltage of the DC-DC converter and an actual input voltage of the DC-DC converter, and controlling the on and off of the plurality of switch tubes to charge and discharge the capacitor unit through different charge and discharge circuits according to a magnitude relationship between the duty cycle and a preset value further includes: In response to the DC-DC converter being in the boost mode and the duty cycle being less than the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows: In a first time period, based on the duty cycle, a power transistor in a switch tube in the upper bridge arm located between the first node and the neutral point of the switch unit is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off, and a diode in a switch tube in the lower bridge arm located between the other end of the switch unit and the second node is turned on; In a second time period, based on the duty cycle, the power transistors in the plurality of switch tubes are controlled to be turned off, the diode in the switch tube in the upper bridge arm between one end of the switch unit and the first node is turned on, and the diode in the switch tube in the lower bridge arm between the other end of the switch unit and the second node is turned on; In a third time period, based on the duty cycle, a power transistor in a switch tube in the lower bridge arm located between the neutral point of the switch unit and the second node is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off, and a diode in a switch tube in the upper bridge arm located between the first node and one end of the switch unit is turned on; In the fourth time period, the power transistors in the multiple switching tubes are cut off based on the duty cycle control, the diode in the switching tube in the upper bridge arm located between one end of the switching unit and the first node is turned on, and the diode in the switching tube in the lower bridge arm located between the other end of the switching unit and the second node is turned on.

10. The control method of the DC-DC converter according to claim 7, characterized in that: The step of determining a duty cycle according to a ratio between a target output voltage of the DC-DC converter and an actual input voltage of the DC-DC converter, and controlling the on and off of the plurality of switch tubes to charge and discharge the capacitor unit through different charge and discharge circuits according to a magnitude relationship between the duty cycle and a preset value further includes: In response to the DC-DC converter being in the boost mode and the duty cycle being greater than or equal to the preset value, the first time period, the second time period, the third time period and the fourth time period in a single control cycle are controlled as follows: In a first time period, based on the duty cycle, a power transistor in a switch tube between the first node and the second node is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off; In a second time period, based on the duty cycle, a power transistor in a switch tube in the upper bridge arm located between the first node and the neutral point of the switch unit is controlled to be turned on, and power transistors in other switch tubes are controlled to be turned off, and a diode in a switch tube in the lower bridge arm located between the other end of the switch unit and the second node is turned on; In a third time period, based on the duty cycle, the power transistor in the switch tube between the first node and the second node is controlled to be turned on, and the power transistors in other switch tubes are controlled to be turned off; In the fourth time period, the power transistor in the switch tube in the lower bridge arm located between the neutral point of the switch unit and the second node is turned on based on the duty cycle, and the power transistors in other switch tubes are turned off, and the diode in the switch tube in the upper bridge arm located between one end of the switch unit and the first node is turned on.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program or an instruction, which, when executed by a processor, causes the processor to execute the control method according to any one of claims 6 to 10.

12. A converter controller, characterized in that: The converter controller comprises a memory and a processor, wherein the memory stores a program or an instruction, and when the program or the instruction is executed by the processor, the processor is prompted to execute the control method according to any one of claims 6 to 10.

13. A converter, characterized in that: Comprising a DC-DC converter according to any one of claims 1 to 5.

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