Flying capacitor-based multi-level bidirectional buck-boost DCDC converter
By designing the Bus side and DC side bucking units in the fly capacitance multi-level circuit, combining reasonable topological layout and precharge resistor configuration, the problem of rising number of fly capacitances and single converter mode is solved, and the problem of achieving the Bidirectional buck-up control reduces cost and volume, and improves reliability and versatility.
Patent Information
- Application Number
- CN202411384382.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2024-12-27
AI Technical Summary
As the number of existing fly capacitance multi-level circuits increases exponentially, the number of fly capacitances increases, resulting in an increase in the volume and weight of the circuit. At the same time, traditional converters can only achieve step-down or boost modes and cannot meet the storage. The energy field requires bidirectional buck control.
A multi-level bidirectional buck-up DCDC converter based on fly capacitance is designed, using Bus side buck-up unit and DC side buck-up unit to reduce fly capacitance through reasonable topological layout and pre-charge resistor configuration. and the number of precharge resistors to achieve step-down and boost control.
It effectively reduces the number of flyover capacitors and precharge resistors, reduces product cost and volume, improves product reliability, and achieves stable operation in different modes, improving the versatility of the converter.
Smart Images
Figure CN119210138A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a converter, in particular to a flying capacitor-based multi-level bidirectional buck-boost DCDC converter. Background Art
[0002] At present, flying capacitor type multi-level circuits are widely used in converters and other fields due to their simple topology and easy solution to the voltage balancing problem. However, as the number of levels of the existing flying capacitor type multi-level circuit increases, the number of flying capacitors used increases exponentially. For example, a flying capacitor type three-level circuit only requires one level of flying capacitor, while a five-level circuit, a seven-level circuit, and a nine-level circuit require three-level, five-level, and seven-level flying capacitors, respectively. At the same time, the voltage borne by each level of flying capacitor also increases step by step. Taking the three-level flying capacitor as an example, the voltage borne by the second-level flying capacitor is twice that of the first-level flying capacitor, and the voltage borne by the third-level flying capacitor is three times that of the first-level flying capacitor, which will cause the volume and number of the second-level and third-level flying capacitors to be much larger than the volume of the first-level flying capacitor. Therefore, the three-level flying capacitor of the five-level circuit will use 6 sub-flying capacitors in actual engineering applications, the five-level flying capacitor of the seven-level circuit will use 15 sub-flying capacitors in actual engineering applications, and the seven-level flying capacitor of the nine-level circuit will use 28 sub-flying capacitors in actual engineering applications, which will greatly increase the volume and weight of the entire DCDC converter.
[0003] In the field of energy storage and other new energy, when the charger charges the battery, if the battery voltage is low, the converter works in buck mode. When the battery voltage rises above the DC bus, the converter needs to work in boost mode. The traditional non-isolated Buck converter can only achieve buck mode, and the Boost converter can only achieve boost mode. Therefore, as the bus voltage of energy storage photovoltaics gradually increases, it is urgent to develop a converter that can achieve both buck control and boost control based on optimizing the number of flying capacitors. Summary of the invention
[0004] The purpose of the present invention is to solve the technical problems that the number of flying capacitors in the existing flying capacitor type multi-level circuit increases exponentially with the increase of the number of levels, resulting in an increase in the volume and weight of the entire circuit, and the traditional non-isolated Buck converter can only achieve a buck mode, and the Boost converter can only achieve a boost mode, and provide a flying capacitor type multi-level bidirectional buck-boost DCDC converter.
[0005] In order to achieve the above purpose, the technical solution provided by the present invention is as follows:
[0006] A flying capacitor-based multi-level bidirectional buck-boost DCDC converter, which is special in that it includes a bus-side buck-boost unit, a DC-side buck-boost unit, a first filter inductor and a second filter inductor;
[0007] The bus-side buck-boost unit includes two groups of bus capacitors, 2N groups of switch tubes and 2N-2 groups of flying capacitors, where N≥2;
[0008] Each group of bus capacitors includes P sub-bus capacitors connected in series, where P≥1; the two groups of bus capacitors are connected in series, and the other ends of the two groups of bus capacitors are connected to the high voltage end and the low voltage end of the bus voltage respectively;
[0009] Each group of switch tubes includes a switch tube SA and a switch tube SB; the 2N groups of switch tubes are divided into two parts; the N switch tubes SA of the first part are connected in series in sequence, and the N switch tubes SB are connected in series in sequence, and the first switch tube SA and the first switch tube SB are both connected to one end of the first filter inductor, and the Nth switch tube SA is connected to the high-voltage end of the bus voltage; the N switch tubes SA of the second part are connected in series in sequence, and the N switch tubes SB are connected in series in sequence, and the first switch tube SA and the first switch tube SB are both connected to one end of the second filter inductor, and the Nth switch tube SA is connected to the low-voltage end of the bus voltage; the Nth switch tube SB of the first part and the Nth switch tube SB of the second part are both connected between the first group of bus capacitors and the second group of bus capacitors;
[0010] The phase shift angles between the i-th switch tube SA in the second part and the i-th switch tube SA in the first part, between the j-th switch tube SA in the first part and the j-1-th switch tube SA in the second part, and between the first switch tube SA in the first part and the N-th switch tube SA in the second part are all 360°÷2N, i=1,2,…,N, j=2,3,…,N;
[0011] 2N-2 groups of flying capacitors are equally divided into two parts; one end of the kth flying capacitor of the two parts is connected between the corresponding kth and k+1th switch tubes SA, and the other end is connected between the corresponding kth and k+1th switch tubes SB, k=1,2,…,N-1; the DC side buck-boost unit has the same circuit topology as the Bus side buck-boost unit, and the other ends of its two groups of bus capacitors are respectively connected to the output high end and the output low end, the first switch tube SA and the first switch tube SB of the first part are both connected to the other end of the first filter inductor, and the Nth switch tube SA is connected to the output high end, the first switch tube SA and the first switch tube SB of the second part are both connected to the other end of the second filter inductor, and the Nth switch tube SA is connected to the output low end.
[0012] Furthermore, it also includes 2N-2 groups of pre-charge resistors;
[0013] Divide the 2N-2 group of pre-charge resistors into two parts;
[0014] The qth level pre-charging resistors of the two parts are connected in parallel at both ends of the corresponding q+1th level flying capacitor, q=1,2,…,N-2, and the N-1th level pre-charging resistors are connected in parallel at both ends of a corresponding group of busbar capacitors; each level of pre-charging resistors includes three sub-pre-charging resistors connected in series in sequence, and the second sub-pre-charging resistor in the kth level pre-charging resistors is connected in parallel at both ends of the corresponding kth level flying capacitor; the resistance ratio of the three sub-pre-charging resistors in the first level pre-charging resistors of the two parts is 1:2:1, and the resistance ratio of the equivalent resistance of the first sub-pre-charging resistor, the second sub-pre-charging resistor in the kth level pre-charging resistor and the corresponding k-1th level pre-charging resistor in parallel and the third sub-pre-charging resistor is 1:2k:1.
[0015] Furthermore, the switch tube SA and the switch tube SB are both MOSFETs;
[0016] Alternatively, the switch tube SA and the switch tube SB are both IGBTs.
[0017] Furthermore, the switch tube SA and the switch tube SB are both NMOS tubes;
[0018] The N switch tubes SA of the first part of the bus-side buck-boost unit are connected at the drain and source in sequence, and the corresponding N switch tubes SB are connected at the source and drain in sequence; the N switch tubes SA of the second part are connected at the drain and source in sequence, and the corresponding N switch tubes SB are connected at the source and drain in sequence; the source of the first switch tube SA of the first part and the drain of the first switch tube SB are both connected to one end of the first filter inductor, and the drain of the Nth switch tube SA is connected to the high-voltage end of the bus voltage; the drain of the first switch tube SA of the second part and the source of the first switch tube SB are both connected to the second One end of the filter inductor and the source of the Nth switch tube SA are connected to the low-voltage end of the bus voltage; the source of the Nth switch tube SB in the first part and the drain of the Nth switch tube SB in the second part are both connected between the first group of bus capacitors and the second group of bus capacitors; one end of the kth flying capacitor in the first part is connected to the source of the corresponding k+1th switch tube SA, and the other end is connected to the drain of the corresponding k+1th switch tube SB; one end of the kth flying capacitor in the second part is connected to the drain of the corresponding k+1th switch tube SA, and the other end is connected to the source of the corresponding k+1th switch tube SB.
[0019] Furthermore, each flying capacitor stage includes Q sub-flying capacitors connected in series, where Q≤k.
[0020] Furthermore, P≤N.
[0021] Furthermore, a diode is connected in parallel to the switch tube SA and the switch tube SB respectively.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] 1. The present invention provides a flying capacitor-based multi-level bidirectional buck-boost DCDC converter. Compared with the existing flying capacitor-based multi-level bidirectional buck-boost circuit, the present invention not only greatly reduces the number of flying capacitors, effectively reduces product cost and product volume, and improves product reliability through reasonable topological layout; at the same time, by setting a Bus-side buck-boost unit and a DC-side buck-boost unit, both buck control and boost control can be achieved, so that the DCDC converter can stably work in various modes such as buck and boost.
[0024] 2. The present invention provides a flying capacitor-based multi-level bidirectional buck-boost DCDC converter, which reduces the number of flying capacitors and the number of pre-charging resistors accordingly. At the same time, the present invention balances the voltage through two groups of bus capacitors. Each group of bus capacitors of the Bus-side buck-boost unit and the DC-side buck-boost unit only bears 1 / 2 of the bus voltage. This setting greatly reduces the voltage borne by the pre-charging resistors, thereby reducing the withstand voltage requirements and resistance losses of the pre-charging resistors.
[0025] 3. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter provided by the present invention is easy to expand to more level topologies and has greatly improved versatility. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 A topological diagram of a flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to Embodiment 1 of the present invention;
[0027] Figure 2 A topological diagram for setting pre-charging resistance in the first embodiment of the present invention;
[0028] Figure 3 This is a timing waveform diagram of controlling the input voltage to be higher than the output voltage in the first embodiment of the present invention;
[0029] Figure 4 This is a timing waveform diagram of controlling the input voltage to be close to the output voltage in the first embodiment of the present invention;
[0030] Figure 5 This is a timing waveform diagram of controlling the input voltage to be lower than the output voltage in the first embodiment of the present invention;
[0031] Figure 6 To invent a topology diagram of a flying capacitor-based multi-level bidirectional buck-boost DCDC converter embodiment 2;
[0032] Figure 7 A topological diagram of setting pre-charging resistance in the second embodiment of the invention. DETAILED DESCRIPTION
[0033] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.
[0034] Embodiment 1
[0035] like Figure 1 As shown, a flying capacitor-based five-level bidirectional buck-boost DCDC converter includes a Bus-side buck-boost unit, a DC-side buck-boost unit, a first filter inductor Ls1 and a second filter inductor Ls2.
[0036] The circuit topology of the bus-side buck-boost unit and the DC-side buck-boost unit are exactly the same. The two units differ only in the external connection relationship and the control of the switch tube. The specific circuit topology is described below using the bus-side buck-boost unit as an example.
[0037] The bus-side buck-boost unit includes two groups of bus capacitors, four groups of switch tubes and two groups of flying capacitors. Each group of bus capacitors includes two sub-bus capacitors connected in series. The two sub-bus capacitors of the first group of bus capacitors are respectively recorded as sub-bus capacitor B-Cbus11 and sub-bus capacitor B-Cbus12, and the two sub-bus capacitors of the second group of bus capacitors are respectively recorded as sub-bus capacitor B-Cbus21 and sub-bus capacitor B-Cbus22. Sub-bus capacitor B-Cbus11, sub-bus capacitor B-Cbus12, sub-bus capacitor B-Cbus21, and sub-bus capacitor B-Cbus22 are connected in series in sequence, and the other end of sub-bus capacitor B-Cbus11 is connected to the high-voltage end Bus+ of the bus voltage, and the other end of sub-bus capacitor B-Cbus22 is connected to the low-voltage end Bus- of the bus voltage.
[0038] Each group of switch tubes includes a switch tube SA and a switch tube SB. When the circuit is powered on, the switch tube SA and the switch tube SB in the same group need to be controlled to be complementary and turned on. The switch tube SA and the switch tube SB can be MOSFET, IGBT, or other types of switch tubes. In this embodiment, the switch tube SA and the switch tube SB are both NMOS tubes. At the same time, each switch tube SA and the switch tube SB are respectively connected in parallel with a diode for freewheeling of the switch tube.
[0039] The four groups of switch tubes are divided into two parts. The first part includes two switch tubes SA and two switch tubes SB, which are respectively recorded as switch tube B-S1A, switch tube B-S3A, switch tube B-S1B, and switch tube B-S3B. The second part includes another two switch tubes SA and two switch tubes SB, which are respectively recorded as switch tube B-S2A, switch tube B-S4A, switch tube B-S2B, and switch tube B-S4B.
[0040] The drain of switch tube B-S3A is connected to the high voltage end Bus+ of the bus voltage, and its source is connected to the drain of switch tube B-S1A. The source of switch tube B-S1A and the drain of switch tube B-S1B are both connected to one end of the first filter inductor Ls1, and the source of switch tube B-S1B is connected to the drain of switch tube B-S3B. The source of switch tube B-S4A is connected to the low voltage end Bus- of the bus voltage, and its drain is connected to the source of switch tube B-S2A. The drain of switch tube B-S2A and the source of switch tube B-S2B are both connected to one end of the second filter inductor Ls2, and the drain of switch tube B-S2B is connected to the source of switch tube B-S4B. The source of switch tube B-S3B and the drain of switch tube B-S4B are both connected between sub-bus capacitor B-Cbus12 and sub-bus capacitor B-Cbus21.
[0041] Among them, the phase angle of switch tube B-S2A lagging or leading switch tube B-S1A, the phase angle of switch tube B-S3A lagging or leading switch tube B-S2A, the phase angle of switch tube B-S4A lagging or leading switch tube B-S3A, and the phase angle of switch tube B-S1A lagging or leading switch tube B-S4A are all 360°÷2N, that is, the phase misalignment angles between the above switch tubes are all 360°÷4=90°. Correspondingly, the phase angle of switch tube B-S2B lagging or leading switch tube B-S1B, the phase angle of switch tube B-S3B lagging or leading switch tube B-S2B, the phase angle of switch tube B-S4B lagging or leading switch tube B-S3B, and the phase angle of switch tube B-S1B lagging or leading switch tube B-S4B are all 90°.
[0042] At the same time, the two groups of flying capacitors are divided into two parts, and each part in this embodiment includes only one group of flying capacitors, and this group of flying capacitors is used as the first-level flying capacitor. Each level of flying capacitor can use a sub-flying capacitor, or it can use multiple sub-flying capacitors connected in series when the voltage is large according to the size of the withstand voltage. In this embodiment, the first-level flying capacitors of the two parts each include a sub-flying capacitor. The capacitor of the first part in the Bus side buck-boost unit is recorded as a sub-flying capacitor B-Cf11, and the capacitor of the second part is recorded as a sub-flying capacitor B-Cf21. One end of the sub-flying capacitor B-Cf11 is connected to the source of the switch tube B-S3A, and the other end is connected to the drain of the switch tube B-S3B. One end of the sub-flying capacitor B-Cf21 is connected to the drain of the switch tube B-S4A, and the other end is connected to the source of the switch tube B-S4B.
[0043] In addition, Figure 2As shown, the Bus-side buck-boost unit also includes two groups of pre-charging resistors for charging the corresponding flying capacitors. The two groups of pre-charging resistors are also divided into two parts, that is, each part includes a group of pre-charging resistors, and this group of pre-charging resistors is used as the first-level pre-charging resistors. Each level of pre-charging resistors includes three sub-pre-charging resistors connected in series in sequence. In this embodiment, the first part includes sub-pre-charging resistors B-Rf11, sub-pre-charging resistors B-Rf12, and sub-pre-charging resistors B-Rf13 connected in series in sequence, and the second part includes sub-pre-charging resistors B-Rf21, sub-pre-charging resistors B-Rf22, and sub-pre-charging resistors B-Rf23 connected in series in sequence. The first-level pre-charging resistor of the first part is connected in parallel at both ends of the first group of bus capacitors, that is, the other end of the sub-pre-charging resistor B-Rf11 is connected to the other end of the sub-bus capacitor B-Cbus11, and the other end of the sub-pre-charging resistor B-Rf13 is connected between the sub-bus capacitor B-Cbus12 and the sub-bus capacitor B-Cbus21; the first-level pre-charging resistor of the second part is connected in parallel at both ends of the second group of bus capacitors, that is, the other end of the sub-pre-charging resistor B-Rf21 is connected between the sub-bus capacitor B-Cbus12 and the sub-bus capacitor B-Cbus21, and the other end of the sub-pre-charging resistor B-Rf23 is connected to the other end of the sub-bus capacitor Cbus22. At the same time, the sub-pre-charging resistor B-Rf12 is connected in parallel at both ends of the sub-flying capacitor B-Cf11, and the sub-pre-charging resistor B-Rf22 is connected in parallel at both ends of the sub-flying capacitor B-Cf21.
[0044] The circuit topology of the DC side buck-boost unit is the same as that of the Bus side buck-boost unit. The two sub-bus capacitors of the first group of bus capacitors in the DC side buck-boost unit are respectively recorded as sub-bus capacitor D-Cbus11 and sub-bus capacitor D-Cbus12, and the two sub-bus capacitors of the second group of bus capacitors are respectively recorded as sub-bus capacitor D-Cbus21 and sub-bus capacitor D-Cbus22. The other end of the sub-bus capacitor D-Cbus11 is connected to the output high-end DC+, and the other end of the sub-bus capacitor D-Cbus22 is connected to the output low-end DC-. The two switch tubes SA and the two switch tubes SB in the first part of the DC side buck-boost unit are respectively recorded as switch tube D-S1A, switch tube D-S3A, switch tube D-S1B, and switch tube D-S3B, and the two switch tubes SA and the two switch tubes SB in the second part are respectively recorded as switch tube B-S2A, switch tube B-S4A, switch tube B-S2B, and switch tube B-S4B, then the drain of switch tube D-S3A is connected to the output terminal DC+, the source of switch tube D-S1A and the drain of switch tube D-S1B are both connected to the other end of the first filter inductor Ls1. The source of switch tube D-S4A is connected to the output low end DC-, and the drain of switch tube D-S2A and the source of switch tube D-S2B are both connected to the other end of the second filter inductor Ls2. The source of the switch tube D-S3B and the drain of the switch tube D-S4B are both connected between the sub-bus capacitor D-Cbus12 and the sub-bus capacitor D-Cbus21.
[0045] In the present invention, the voltage is evenly divided by two groups of bus capacitors, that is, each group of bus capacitors in the DC side buck-boost unit and the Bus side buck-boost unit bears 1 / 2 of the bus voltage, and in this embodiment, both parts of the DC side buck-boost unit and the Bus side buck-boost unit have only first-stage pre-charging resistors, and the resistance ratio of the sub-pre-charging resistor B-Rf11, the sub-pre-charging resistor B-Rf12, and the sub-pre-charging resistor B-Rf13 of the first part is 1:2:1, and the resistance ratio of the sub-pre-charging resistor B-Rf21, the sub-pre-charging resistor B-Rf22, and the sub-pre-charging resistor B-Rf23 of the second part is also 1:2:1. Since the first-stage flying capacitors of the two parts bear 1 / 4 of the bus voltage respectively, each stage of the pre-charging resistor of the two parts only needs to withstand 1 / 2 of the bus voltage. Compared with the existing flying capacitor type multi-level circuit, the flying capacitor type multi-level circuit of the present invention greatly reduces the voltage borne by the pre-charging resistor, thereby reducing the withstand voltage requirement and resistance loss of the pre-charging resistor.
[0046] The specific working principle is: when the input voltage is higher than the output voltage, the DCDC converter works in the buck mode, all the switch tubes SA in the DC side buck-boost unit are always turned on, all the switch tubes SB are always turned off, all the switch tubes SA and the corresponding switch tubes SB in the Bus side buck-boost unit are complementary turned on, and the control method is pulse width modulation. The relationship between the DC voltage of the DC side buck-boost unit, the DC voltage of the Bus side buck-boost unit, and the conduction duty cycle of the switch tube SA in the Bus side buck-boost unit can be approximately calculated by the following formula:
[0047] V DC ≈V BUS ×D BUS
[0048] In the above formula, V DC is the DC voltage of the DC side buck-boost unit;
[0049] V Bus is the DC voltage of the buck-boost unit on the Bus side;
[0050] D BUS It is the conduction duty cycle of the switch tube SA in the buck-boost unit on the Bus side.
[0051] When the input voltage is close to the output voltage, all the switch tubes SA in the Bus-side buck-boost unit are complementary to the corresponding switch tubes SB, and all the switch tubes SA in the DC-side buck-boost unit are complementary to the corresponding switch tubes SB. The relationship between the DC-side buck-boost unit's DC voltage, the Bus-side buck-boost unit's DC voltage, the conduction duty cycle of the switch tubes SA in the Bus-side buck-boost unit, and the conduction duty cycle of the switch tubes SB in the DC-side buck-boost unit can be approximately calculated by the following formula:
[0052]
[0053] In the above formula, D DC is the conduction duty cycle of the switch tube SB in the DC side buck-boost unit.
[0054] When the input voltage is lower than the output voltage, all the switch tubes SA in the Bus-side buck-boost unit are always turned on, all the switch tubes SB are always turned off, and all the switch tubes SA and the corresponding switch tubes SB in the DC-side buck-boost unit are complementary turned on. The relationship between the DC voltage of the DC-side buck-boost unit, the DC voltage of the Bus-side buck-boost unit, and the conduction duty cycle of the switch tube SB in the DC-side buck-boost unit can be approximately calculated by the following formula:
[0055]
[0056] like Figure 3As shown in the figure, it is a timing waveform diagram of controlling the input voltage to be higher than the output voltage in this embodiment, wherein BG1A is the driving waveform of the switch tube B-S1A, BG1B is the driving waveform of the switch tube B-S1B, BG2A is the driving waveform of the switch tube B-S2A, BG2B is the driving waveform of the switch tube B-S2B, BG3A is the driving waveform of the switch tube B-S3A, BG3B is the driving waveform of the switch tube B-S3B, BG4A is the driving waveform of the switch tube B-S4A, and BG4B is the driving waveform of switch tube B-S4B, DG1A is the driving waveform of switch tube D-S1A, DG1B is the driving waveform of switch tube D-S1B, DG2A is the driving waveform of switch tube D-S2A, DG2B is the driving waveform of switch tube D-S2B, DG3A is the driving waveform of switch tube D-S3A, DG3B is the driving waveform of switch tube D-S3B, DG4A is the driving waveform of switch tube D-S4A, and DG4B is the driving waveform of switch tube D-S4B. Figure 4 : is a timing waveform diagram of controlling the input voltage to be close to the output voltage in this embodiment, Figure 5 1 is a timing waveform diagram of controlling the input voltage to be lower than the output voltage in this embodiment.
[0057] Compared with the existing flying capacitor type five-level circuit, the present invention is a flying capacitor type five-level bidirectional buck-boost DCDC converter, the number of sub-flying capacitors in the DC side buck-boost unit and the Bus side buck-boost unit is reduced from 6 to 2, and the pre-charging circuit (the number of pre-charging resistors) of the flying capacitors in the two units is also reduced from 3 to 2. In addition, by setting the Bus side buck-boost unit and the DC side buck-boost unit, both buck control and boost control can be achieved.
[0058] Embodiment 2
[0059] like Figure 6 As shown, a flying capacitor-based nine-level bidirectional buck-boost DCDC converter is different from the first embodiment only in the number of sub-bus capacitors, switch tubes and flying capacitors in the bus-side buck-boost unit and the DC-side buck-boost unit. Also taking the bus-side buck-boost unit as an example, this embodiment includes two groups of bus capacitors, eight groups of switch tubes and six groups of flying capacitors.
[0060] Each group of bus capacitors includes four sub-bus capacitors. The four sub-bus capacitors of the first group of bus capacitors are respectively recorded as sub-bus capacitor B-Cbus11, sub-bus capacitor B-Cbus12, sub-bus capacitor B-Cbus13 and sub-bus capacitor B-Cbus14, and the three sub-bus capacitors of the second group of bus capacitors are respectively recorded as sub-bus capacitor B-Cbus21, sub-bus capacitor B-Cbus22, sub-bus capacitor B-Cbus23 and sub-bus capacitor B-Cbus24. The sub-bus capacitor B-Cbus11, the sub-bus capacitor B-Cbus12, the sub-bus capacitor B-Cbus13, the sub-bus capacitor B-Cbus14, the sub-bus capacitor B-Cbus21, the sub-bus capacitor B-Cbus22, the sub-bus capacitor B-Cbus23, and the sub-bus capacitor B-Cbus24 are connected in series in sequence, and the other end of the sub-bus capacitor B-Cbus11 is connected to the high-voltage end Bus+ of the bus voltage, and the other end of the sub-bus capacitor B-Cbus24 is connected to the low-voltage end Bus- of the bus voltage.
[0061] The selection and setting of each group of switch tubes are the same as those in Example 1. The eight groups of switch tubes are divided into two parts. The first part includes switch tube B-S1A, switch tube B-S3A, switch tube B-S5A, switch tube B-S7A, switch tube B-S1B, switch tube B-S3B, switch tube S5B, and switch tube S7B; the source of switch tube B-S3A is connected to the drain of switch tube B-S1A, the source of switch tube B-S5A is connected to the drain of switch tube B-S3A, and the source of switch tube B-S7A is connected to the drain of switch tube B-S3A. The drain of the switch tube B-S5A is connected, the drain of the switch tube B-S3B is connected to the source of the switch tube B-S1B, the drain of the switch tube S5B is connected to the source of the switch tube B-S3B, the drain of the switch tube S7B is connected to the source of the switch tube B-S5B, the source of the switch tube B-S1A and the drain of the switch tube B-S1B are both connected to one end of the first filter inductor Ls1, and the drain of the switch tube B-S7A is connected to the high-voltage end Bus+ of the bus voltage. The second part includes switch tube B-S2A, switch tube B-S4A, switch tube B-S6A, switch tube B-S8A, switch tube B-S2B, switch tube B-S4B, switch tube B-S6B, and switch tube B-S8B; the drain of switch tube B-S4A is connected to the source of switch tube B-S2A, the drain of switch tube B-S6A is connected to the source of switch tube B-S4A, and the drain of switch tube B-S8A is connected to the source of switch tube B- The source of switch tube B-S6A, the source of switch tube B-S4B is connected to the drain of switch tube B-S2B, the source of switch tube B-S6B is connected to the drain of switch tube B-S4B, the source of switch tube B-S8B is connected to the drain of switch tube B-S6B, the drain of switch tube B-S2A and the source of switch tube B-S2B are both connected to one end of the second filter inductor Ls2, and the source of switch tube B-S8A is connected to the low-voltage end Bus- of the bus voltage. The source of switch tube B-S7B in the first part and the drain of switch tube B-S8B in the second part are both connected between sub-bus capacitor B-Cbus14 and sub-bus capacitor B-Cbus21.
[0062] Among them, the phase angle of switch tube B-S2A lagging or leading switch tube B-S1A, the phase angle of switch tube B-S3A lagging or leading switch tube B-S2A, the phase angle of switch tube B-S4A lagging or leading switch tube B-S3A, the phase angle of switch tube B-S5A lagging or leading switch tube B-S4A, the phase angle of switch tube B-S6A lagging or leading switch tube B-S5A, the phase angle of switch tube B-S7A lagging or leading switch tube B-S6A, the phase angle of switch tube B-S8A lagging or leading switch tube B-S7A, and the phase angle of switch tube B-S1A lagging or leading switch tube B-S8A are all 360°÷2N, that is, the phase mismatch angles between the above switch tubes are all 360°÷8=45°. Correspondingly, the phase mismatch angles between the corresponding switch tubes SB are also set according to the above rules.
[0063] The six groups of flying capacitors are divided into two parts, that is, each part includes three groups of flying capacitors, and they are used as three-level flying capacitors. The first-level flying capacitor of the first part only includes one sub-flying capacitor B-Cf11, the second-level flying capacitor includes a sub-flying capacitor B-Cf31 and a sub-flying capacitor B-Cf32 connected in series in sequence, and the third-level flying capacitor includes a sub-flying capacitor B-Cf51, a sub-flying capacitor B-Cf52 and a sub-flying capacitor B-Cf53 connected in series in sequence; one end of the sub-flying capacitor B-Cf11 is connected to the source of the switching tube B-S3A, and the other end is connected to the drain of the switching tube B-S3B, the other end of the sub-flying capacitor B-Cf31 is connected to the source of the switching tube B-S5A, the other end of the sub-flying capacitor B-Cf32 is connected to the drain of the switching tube B-S5B, the other end of the sub-flying capacitor B-Cf51 is connected to the source of the switching tube B-S7A, and the other end of the sub-flying capacitor B-Cf53 is connected to the drain of the switching tube B-S7B. The first-level flying capacitor of the second part includes only one sub-flying capacitor B-Cf21, the second-level flying capacitor includes sub-flying capacitor B-Cf41 and sub-flying capacitor B-Cf42 connected in series in sequence, and the third-level flying capacitor includes sub-flying capacitor B-Cf61, sub-flying capacitor B-Cf62 and sub-flying capacitor B-Cf63 connected in series in sequence; one end of the sub-flying capacitor B-Cf21 is connected to the drain of the switching tube B-S4A, and the other end is connected to the source of the switching tube B-S4B, the other end of the sub-flying capacitor B-Cf42 is connected to the drain of the switching tube B-S6A, the other end of the sub-flying capacitor B-Cf41 is connected to the source of the switching tube B-S6B, the other end of the sub-flying capacitor B-Cf63 is connected to the drain of the switching tube B-S8A, and the other end of the sub-flying capacitor B-Cf61 is connected to the source of the switching tube B-S8B.
[0064] like Figure 7As shown, this embodiment also includes six corresponding groups of pre-charging resistors, and the six groups of pre-charging resistors are also divided into two parts, that is, each part includes three groups of pre-charging resistors, and they are used as three-level pre-charging resistors. The first-level pre-charging resistor of the first part includes a sub-pre-charging resistor B-Rf11, a sub-pre-charging resistor B-Rf12, and a sub-pre-charging resistor B-Rf13 connected in series in sequence, the second-level pre-charging resistor includes a sub-pre-charging resistor B-Rf31, a sub-pre-charging resistor B-Rf32, and a sub-pre-charging resistor B-Rf33 connected in series in sequence, and the third-level pre-charging resistor includes a sub-pre-charging resistor B-Rf51, a sub-pre-charging resistor B-Rf52, and a sub-pre-charging resistor B-Rf53 connected in series in sequence; the other end of the sub-pre-charging resistor B-Rf11 is connected to the other end of the sub-flying capacitor B-Cf31. One end, the other end of the sub-pre-charging resistor B-Rf13 is connected to the other end of the sub-flying capacitor B-Cf32, the other end of the sub-pre-charging resistor B-Rf31 is connected to the other end of the sub-flying capacitor B-Cf51, the other end of the sub-pre-charging resistor B-Rf33 is connected to the other end of the sub-flying capacitor B-Cf53, the other end of the sub-pre-charging resistor B-Rf51 is connected to the other end of the sub-bus capacitor B-Cbus11, and the other end of the sub-pre-charging resistor B-Rf53 is connected between the sub-bus capacitor B-Cbus14 and the sub-bus capacitor B-Cbus21. The first-stage pre-charging resistor of the second part includes a sub-pre-charging resistor B-Rf21, a sub-pre-charging resistor B-Rf22, and a sub-pre-charging resistor B-Rf23 connected in series in sequence, the second-stage pre-charging resistor includes a sub-pre-charging resistor B-Rf41, a sub-pre-charging resistor B-Rf42, and a sub-pre-charging resistor B-Rf43 connected in series in sequence, and the third-stage pre-charging resistor includes a sub-pre-charging resistor B-Rf61, a sub-pre-charging resistor B-Rf62, and a sub-pre-charging resistor B-Rf63 connected in series in sequence; the other end of the sub-pre-charging resistor B-Rf21 is connected to the other end of the sub-flying capacitor B-Cf41. One end, the other end of the sub-pre-charging resistor B-Rf23 is connected to the other end of the sub-flying capacitor B-Cf42, the other end of the sub-pre-charging resistor B-Rf41 is connected to the other end of the sub-flying capacitor B-Cf61, the other end of the sub-pre-charging resistor B-Rf43 is connected to the other end of the sub-flying capacitor B-Cf63, the other end of the sub-pre-charging resistor B-Rf61 is connected between the sub-bus capacitor B-Cbus14 and the sub-bus capacitor B-Cbus21, and the other end of the sub-pre-charging resistor B-Rf63 is connected to the other end of the sub-bus capacitor B-Cbus24.At the same time, in the first part, the sub-pre-charging resistor B-Rf12 is connected in parallel to both ends of the sub-flying capacitor B-Cf11, the sub-pre-charging resistor B-Rf32 is connected in parallel to both ends of the corresponding second-stage flying capacitor, that is, one end of the sub-pre-charging resistor B-Rf32 is connected to the other end of the sub-flying capacitor B-Cf31, and the other end thereof is connected to the other end of the sub-flying capacitor B-Cf32, and the sub-pre-charging resistor B-Rf52 is connected in parallel to both ends of the corresponding third-stage flying capacitor, that is, one end of the sub-pre-charging resistor B-Rf52 is connected to the sub-flying capacitor B-Cf5 1, and the other end of which is connected to the other end of the sub-flying capacitor B-Cf53; in the second part, the sub-pre-charging resistor B-Rf22 is connected in parallel to the two ends of the sub-flying capacitor B-Cf21, one end of the sub-pre-charging resistor B-Rf42 is connected to the other end of the sub-flying capacitor B-Cf41, and the other end of which is connected to the other end of the sub-flying capacitor B-Cf42, one end of the sub-pre-charging resistor B-Rf62 is connected to the other end of the sub-flying capacitor B-Cf61, and the other end of which is connected to the other end of the sub-flying capacitor B-Cf63.
[0065] The resistance ratio of the sub-pre-charging resistor B-Rf11, sub-pre-charging resistor B-Rf12, and sub-pre-charging resistor B-Rf13 in the first part, and the resistance ratio of the sub-pre-charging resistor B-Rf21, sub-pre-charging resistor B-Rf22, and sub-pre-charging resistor B-Rf23 in the second part are all 1:2:1; the resistance ratio of the equivalent resistance of the sub-pre-charging resistor B-Rf31, sub-pre-charging resistor B-Rf32 connected in parallel with the corresponding first-stage pre-charging resistor in the first part, and the resistance ratio of the sub-pre-charging resistor B-Rf33 in the second part. 1. The resistance ratio of the equivalent resistance after the sub-pre-charging resistor B-Rf42 is connected in parallel with the corresponding first-stage pre-charging resistor and the resistance ratio of the sub-pre-charging resistor B-Rf43 is 1:4:1; the resistance ratio of the equivalent resistance after the sub-pre-charging resistor Rf51 and the sub-pre-charging resistor Rf52 are connected in parallel with the corresponding second-stage pre-charging resistor and the resistance ratio of the sub-pre-charging resistor Rf53 in the first part, and the resistance ratio of the equivalent resistance after the sub-pre-charging resistor Rf61 and the sub-pre-charging resistor Rf62 are connected in parallel with the corresponding second-stage pre-charging resistor and the resistance ratio of the sub-pre-charging resistor Rf63 in the second part are 1:6:1. Each group of bus capacitors bears 1 / 2 of the bus voltage, and accordingly, the first-stage flying capacitors in the two parts bear 1 / 8 of the bus voltage, the second-stage flying capacitors bear 2 / 8 of the bus voltage, and the third-stage flying capacitors bear 3 / 8 of the bus voltage.
[0066] Compared with the existing flying capacitor type nine-level circuit, the present invention is a flying capacitor type nine-level bidirectional buck-boost DCDC converter, the number of flying capacitors in the DC side buck-boost unit and the Bus side buck-boost unit is reduced from 28 to 12, and the pre-charging circuit of the flying capacitor (the number of pre-charging resistors) is also reduced from 7 to 6. Similarly, by setting the Bus side buck-boost unit and the DC side buck-boost unit, both buck control and boost control can be achieved.
[0067] The present invention can be expanded to circuit topologies with more levels as needed. The number of sub-bus capacitors in each group of bus capacitors and the number of sub-flying capacitors in each flying capacitor stage can be adjusted according to actual conditions. Preferably, the number of sub-flying capacitors in each flying capacitor stage is less than or equal to the number of flying capacitor stages, and the number of sub-bus capacitors in the entire circuit is less than or equal to the value of the number of levels minus 1.
[0068] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.
Claims
1. A flying capacitor-based multi-level bidirectional buck-boost DCDC converter, characterized in that: It includes a bus side buck-boost unit, a DC side buck-boost unit, a first filter inductor and a second filter inductor; The bus-side buck-boost unit includes two groups of bus capacitors, 2N groups of switch tubes and 2N-2 groups of flying capacitors, where N≥2; Each group of bus capacitors includes P sub-bus capacitors connected in series, where P≥1; the two groups of bus capacitors are connected in series, and the other ends of the two groups of bus capacitors are connected to the high voltage end and the low voltage end of the bus voltage respectively; Each group of switch tubes includes a switch tube SA and a switch tube SB; the 2N groups of switch tubes are equally divided into two parts; The N switch tubes SA of the first part are sequentially connected in series, and the N switch tubes SB are sequentially connected in series, and the first switch tube SA and the first switch tube SB are both connected to one end of the first filter inductor, and the Nth switch tube SA is connected to the high-voltage end of the bus voltage; the N switch tubes SA of the second part are sequentially connected in series, and the N switch tubes SB are sequentially connected in series, and the first switch tube SA and the first switch tube SB are both connected to one end of the second filter inductor, and the Nth switch tube SA is connected to the low-voltage end of the bus voltage; the Nth switch tube SB of the first part and the Nth switch tube SB of the second part are both connected between the first group of bus capacitors and the second group of bus capacitors; The phase shift angles between the i-th switch tube SA in the second part and the i-th switch tube SA in the first part, between the j-th switch tube SA in the first part and the j-1-th switch tube SA in the second part, and between the first switch tube SA in the first part and the N-th switch tube SA in the second part are all 360°÷2N, i=1,2,…,N, j=2,3,…,N; 2N-2 groups of flying capacitors are equally divided into two parts; one end of the kth flying capacitor of the two parts is connected between the corresponding kth and k+1th switch tubes SA, and the other end is connected between the corresponding kth and k+1th switch tubes SB, k=1,2,…,N-1; the DC side buck-boost unit has the same circuit topology as the Bus side buck-boost unit, and the other ends of its two groups of bus capacitors are respectively connected to the output high end and the output low end, the first switch tube SA and the first switch tube SB of the first part are both connected to the other end of the first filter inductor, and the Nth switch tube SA is connected to the output high end, the first switch tube SA and the first switch tube SB of the second part are both connected to the other end of the second filter inductor, and the Nth switch tube SA is connected to the output low end.
2. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to claim 1, characterized in that: Also includes 2N-2 groups of pre-charge resistors; Divide the 2N-2 group of pre-charge resistors into two parts; The qth level pre-charging resistors of the two parts are connected in parallel at both ends of the corresponding q+1th level flying capacitor, q=1,2,…,N-2, and the N-1th level pre-charging resistors are connected in parallel at both ends of a corresponding group of busbar capacitors; each level of pre-charging resistors includes three sub-pre-charging resistors connected in series in sequence, and the second sub-pre-charging resistor in the kth level pre-charging resistors is connected in parallel at both ends of the corresponding kth level flying capacitor; the resistance ratio of the three sub-pre-charging resistors in the first level pre-charging resistors of the two parts is 1:2:1, and the resistance ratio of the equivalent resistance of the first sub-pre-charging resistor, the second sub-pre-charging resistor in the kth level pre-charging resistor and the corresponding k-1th level pre-charging resistor in parallel and the third sub-pre-charging resistor is 1:2k:
1.
3. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to claim 2, characterized in that: The switch tube SA and the switch tube SB are both MOSFETs; Alternatively, the switch tube SA and the switch tube SB are both IGBTs.
4. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to claim 3, characterized in that: The switch tube SA and the switch tube SB are both NMOS tubes; The N switch tubes SA of the first part of the bus-side buck-boost unit are connected at the drain and source in sequence, and the corresponding N switch tubes SB are connected at the source and drain in sequence; the N switch tubes SA of the second part are connected at the drain and source in sequence, and the corresponding N switch tubes SB are connected at the source and drain in sequence; the source of the first switch tube SA of the first part and the drain of the first switch tube SB are both connected to one end of the first filter inductor, and the drain of the Nth switch tube SA is connected to the high-voltage end of the bus voltage; the drain of the first switch tube SA of the second part and the source of the first switch tube SB are both connected to the second One end of the filter inductor and the source of the Nth switch tube SA are connected to the low-voltage end of the bus voltage; the source of the Nth switch tube SB in the first part and the drain of the Nth switch tube SB in the second part are both connected between the first group of bus capacitors and the second group of bus capacitors; one end of the kth flying capacitor in the first part is connected to the source of the corresponding k+1th switch tube SA, and the other end is connected to the drain of the corresponding k+1th switch tube SB; one end of the kth flying capacitor in the second part is connected to the drain of the corresponding k+1th switch tube SA, and the other end is connected to the source of the corresponding k+1th switch tube SB.
5. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to claim 1, characterized in that: Each flying capacitor stage includes Q sub-flying capacitors connected in series, where Q≤k.
6. The flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to claim 1, characterized in that: Said P≤N.
7. A flying capacitor-based multi-level bidirectional buck-boost DCDC converter according to any one of claims 1 to 6, characterized in that: The switch tube SA and the switch tube SB are respectively connected with diodes in parallel.