CN213937746U - Three-level booster circuit - Google Patents
Three-level booster circuit Download PDFInfo
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- CN213937746U CN213937746U CN202022945408.XU CN202022945408U CN213937746U CN 213937746 U CN213937746 U CN 213937746U CN 202022945408 U CN202022945408 U CN 202022945408U CN 213937746 U CN213937746 U CN 213937746U
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Abstract
The utility model provides a three-level booster circuit, include: input capacitance
A bypass branch, a boost power conversion circuit,Flying capacitor
Voltage reduction circuit with fixed transformation ratio and direct-current bus capacitor
Said input capacitance
Is connected to the flying capacitor through the bypass branch circuit and the boost power conversion circuit respectively
Said flying capacitor
And DC bus capacitor
The voltage reducing circuit with fixed transformation ratio is connected between the two circuits. The utility model provides a direct current bus have the electricity and flying capacitor does not have electricity or the too low problem of voltage to guarantee the operating voltage stress of switch tube and diode in order to avoid being punctured.
Description
Technical Field
The utility model relates to a boost circuit especially relates to a three-level boost circuit.
Background
In the three-level booster circuit in the prior art, when multiple paths of flying capacitor booster circuits are connected in parallel on the same direct-current bus, after other paths are electrified and the voltage of the direct-current bus is established, if a certain path of flying capacitor booster circuit is not electrified at the moment, the voltage and the input voltage on the flying capacitor are zero, the voltage of the bus is all added to the diode of the path, and the diode of the path is possibly broken down at the moment. In addition, in the string-type photovoltaic inverter, the flying capacitor boost circuit is connected with a first-stage grid-connected inverter circuit, the bus voltage can rapidly rise when the power grid is in high-penetration state, and the flying capacitor voltage cannot be timely charged at the moment, so that the voltage stress on a switching tube or a diode can possibly rise, and the breakdown of the switching tube or the diode can be caused.
Disclosure of Invention
The utility model aims to solve the technical problem that a three-level boost circuit that can avoid direct current bus to have electricity and flying capacitor does not have electricity has been guaranteed to the operating pressure stress of switch tube and diode in order to avoid being punctured needs to be provided.
To this, the utility model provides a three-level boost circuit, include: input capacitance CinBypass branch circuit, boost power conversion circuit and flying capacitor CfVoltage reduction circuit with fixed transformation ratio and direct-current bus capacitor CoSaid input capacitance CinIs connected to the flying capacitor C through the bypass branch circuit and the boost power conversion circuit respectivelyfSaid flying capacitor CfAnd DC bus capacitor CoThe voltage reducing circuit with fixed transformation ratio is connected between the two circuits.
The utility model discloses a further improvement lies in, the step-down circuit of fixed transformation ratio includes diode D5A transformer and a full-bridge rectification circuit, the flying capacitor D5One end near the bypass branch is connected to the diode D5The negative electrode of the diode D5The positive pole of the transformer is connected to the secondary side of the transformer, and the primary side of the transformer is connected to the direct current bus capacitor C through a full-bridge rectification circuito。
The utility model discloses a further improvement lies in, boost power conversion circuit includes inductance L1Diode D4Diode D3Switch tube S1And a switching tube S2Said input capacitance CinOne end of (b) passes through the inductor L1Is connected to the switching tube S2Collector and diode D3The positive pole of (1), the switching tube S2Is connected to the switching tube S1The collector of (1), the switching tube S1Is connected to the input capacitance CinThe other end of the diode D4Is connected to the diode D3The negative electrode of the diode D4Is connected to the bypass branch.
The utility model discloses a further improvement lies in, switch tube S2And said switching tube S1Are all connected to the flying capacitor Cf。
The utility model discloses a further improvement lies in, switch tube S2And said switching tube S1Are connected to the fixed ratio step-down circuit.
The utility model discloses a further improvement lies in, the bypass branch road includes diode D6Said diode D6Is connected to the input capacitance CinSaid diode D6Is connected to the diode D4The negative electrode of (1).
The utility model discloses a further improvement lies in, diode D4Anode and diode D3Are all connected to the flying capacitor Cf。
The utility model discloses a further improvement lies in, diode D4Anode and diode D3Are connected to the step-down circuit of fixed transformation ratio.
Compared with the prior art, the beneficial effects of the utility model reside in that: by means of a flying capacitor CfAnd DC bus capacitor CoA group of voltage reduction circuits with fixed transformation ratio are connected between the flying capacitor C and the flying capacitor CfCan follow the bus voltage VoThe change solves the problems that the flying capacitor is out of power or the voltage is too low due to the power of the DC bus, and can also avoid the voltage V of the DC busoAnd flying capacitor CfVoltage value V ofcfIf the difference is too large, the operating voltage stress of the switch tube S1 and the diode D4 is ensured to avoid breakdown.
Drawings
Fig. 1 is a schematic diagram of a circuit structure according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
Flying capacitor CfThe flying capacitor C of the boost power conversion circuit 2 is in normal operationfThe voltage on should be the bus voltage VoWhen switching tube S1When it is on, the switch tube S2Has a voltage stress of VcfWhen switching tube S2When it is on, the switch tube S1Voltage stress of Vo-VcfTherefore, the voltage stress of the switch tube is about half of the bus voltage, and a switch device with lower voltage stress can be adopted; in order to avoid switching the tube S1Or diode D4Voltage stress V ofo-VcfThe three-level booster circuit is subjected to optimal design and optimal control on the three-level booster circuit.
As shown in fig. 1, the present example provides a three-level booster circuit including: input capacitance CinBypass branch 1, boost power conversion circuit 2 and flying capacitor Cf Voltage reducing circuit 3 with fixed transformation ratio and DC bus capacitor CoSaid input capacitance CinIs connected to the flying capacitor C through the bypass branch circuit 1 and the boost power conversion circuit 2 respectivelyfSaid flying capacitor CfAnd DC bus capacitor CoThe voltage reduction circuit 3 with fixed transformation ratio is connected between the two circuits, so that the flying capacitor C is enabled to be connectedfCan follow the bus voltage VoAnd (4) changing.
The voltage reducing circuit 3 with fixed transformation ratio is adopted in the embodiment because the voltage of the floating capacitor is kept at the bus voltage V when the boosting power conversion circuit 2 works normallyoAbout half of the input inductor current, the ripple of the input inductor current is minimal. And the bus voltage VoCan change according to the working condition of the inverter connected later, and the voltage of the suspension capacitor can always follow the bus voltage V by designing the voltage reduction circuit 3 with fixed transformation ratio to keep the fixed transformation ratiooHalf of that.
In practical operation, it is preferable to preset a first threshold value, which is the voltage V of the busoThe selection of the preset voltage threshold is mainly related to the stress of the switch device, and when the voltage of the floating capacitor is reduced, the diode D4And a switching tube S1The voltage stress of the flying capacitor C is increased, so that when the voltage of the flying capacitor C is required to be reduced to a first threshold value, the voltage reduction circuit 3 with the fixed transformation ratio is started to work, the voltage of the flying capacitor C is charged, and the flying capacitor C is chargedfVoltage value V ofcfIs charged above the first threshold value quickly, thereby solving the problem that the flying capacitor is not charged when the direct current bus is charged and avoiding the voltage V of the direct current busoAnd flying capacitor CfVoltage value V ofcfAnd if the difference is too large, the working voltage stress of the switching tube S1 and the diode D4 is ensured, and the breakdown is avoided. Preferably, the value range of the first threshold in this example satisfies Vo-Vth1＜VtrWherein V istrFor boosting the diode D in the power converter circuit 24And a switching tube S1Maximum voltage stress value, V, allowed for operationth1Is the value of the first threshold, VoIs the dc bus voltage.
FIG. 2 is a schematic diagram of a preferred circuit of the present example; as shown in FIG. 2, the constant-ratio step-down circuit 3 of the present example includes a diode D5A transformer and a full-bridge rectification circuit, the flying capacitor D5One end near the boosting power conversion circuit 2 is connected to the diode D5The negative electrode of the diode D5The positive pole of the transformer is connected to the secondary side of the transformer, the secondary side is an isolated dc/dc circuit rectified by a diode, and the primary side of the transformer is connected to the direct current bus capacitor C through a full-bridge rectification circuito. The transformation ratio of the transformer is N2:N1The primary full bridge can adopt an open-loop control mode, and the flying capacitor C can be connected with the circuit when the circuit worksfVoltage value V ofcfIs controlled at Vo*N1/N2Thereby realizing flying capacitor CfVoltage value V ofcfCan followVoltage V along with busoThe effect of the change.
As shown in fig. 2, the bypass branch 1 of the present example comprises a diode D6Said diode D6Is connected to the input capacitance CinSaid diode D6Is connected to the diode D4The negative electrode of (1). The diode D4Anode and diode D3Are all connected to the flying capacitor CfAnd a step-down circuit 3 of a fixed transformation ratio.
As shown in fig. 2, the boost power converter circuit 2 of the present example includes an inductor L1Diode D4Diode D3Switch tube S1And a switching tube S2Said input capacitance CinOne end of (b) passes through the inductor L1Is connected to the switching tube S2Collector and diode D3The positive pole of (1), the switching tube S2Is connected to the switching tube S1The collector of (1), the switching tube S1Is connected to the input capacitance CinThe other end of the diode D4Is connected to the diode D3The negative electrode of the diode D4Is connected to the bypass branch 1 (i.e. diode D)6Negative electrode of (1). The switch tube S2And said switching tube S1Are all connected to the flying capacitor CfAnd a step-down circuit 3 of a fixed transformation ratio.
In summary, the present example is implemented by using the flying capacitor CfAnd DC bus capacitor CoA set of voltage reduction circuits 3 with fixed transformation ratio are connected between the flying capacitor C and the flying capacitor CfCan follow the bus voltage VoThe change solves the problems that the flying capacitor is out of power or the voltage is too low due to the power of the DC bus, and can also avoid the voltage V of the DC busoAnd flying capacitor CfVoltage value V ofcfIf the difference is too large, the operating voltage stress of the switch tube S1 and the diode D4 is ensured to avoid breakdown.
The above-mentioned embodiments are the preferred embodiments of the present invention, and the scope of the present invention is not limited to the above-mentioned embodiments, and the scope of the present invention includes and is not limited to the above-mentioned embodiments, and all equivalent changes made according to the shape and structure of the present invention are within the protection scope of the present invention.
Claims (8)
1. A three-level boost circuit, comprising: input capacitance CinBypass branch circuit, boost power conversion circuit and flying capacitor CfVoltage reduction circuit with fixed transformation ratio and direct-current bus capacitor CoSaid input capacitance CinIs connected to the flying capacitor C through the bypass branch circuit and the boost power conversion circuit respectivelyfSaid flying capacitor CfAnd DC bus capacitor CoThe voltage reducing circuit with fixed transformation ratio is connected between the two circuits.
2. The tri-level boost circuit of claim 1, in which said fixed-ratio buck circuit comprises a diode D5A transformer and a full-bridge rectification circuit, the flying capacitor D5One end near the bypass branch is connected to the diode D5The negative electrode of the diode D5The positive pole of the transformer is connected to the secondary side of the transformer, and the primary side of the transformer is connected to the direct current bus capacitor C through a full-bridge rectification circuito。
3. The three-level boost circuit of claim 1 or 2, wherein said boost power conversion circuit comprises an inductor L1Diode D4Diode D3Switch tube S1And a switching tube S2Said input capacitance CinOne end of (b) passes through the inductor L1Is connected to the switching tube S2Collector and diode D3The positive pole of (1), the switching tube S2Is connected to the switching tube S1The collector of (1), the switching tube S1Is connected to the input capacitance CinThe other end of the diode D4Is connected to the diodePipe D3The negative electrode of the diode D4Is connected to the bypass branch.
4. Three-level booster circuit according to claim 3, characterized in that the switching tube S2And said switching tube S1Are all connected to the flying capacitor Cf。
5. Three-level booster circuit according to claim 3, characterized in that the switching tube S2And said switching tube S1Are connected to the fixed ratio step-down circuit.
6. The tri-level boost circuit of claim 3, wherein said bypass branch comprises a diode D6Said diode D6Is connected to the input capacitance CinSaid diode D6Is connected to the diode D4The negative electrode of (1).
7. The tri-level boost circuit of claim 3, in which said diode D4Anode and diode D3Are all connected to the flying capacitor Cf。
8. The tri-level boost circuit of claim 3, in which said diode D4Anode and diode D3Are connected to the step-down circuit of fixed transformation ratio.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022945408.XU CN213937746U (en) | 2020-12-10 | 2020-12-10 | Three-level booster circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022945408.XU CN213937746U (en) | 2020-12-10 | 2020-12-10 | Three-level booster circuit |
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| CN213937746U true CN213937746U (en) | 2021-08-10 |
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| CN202022945408.XU Active CN213937746U (en) | 2020-12-10 | 2020-12-10 | Three-level booster circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024037058A1 (en) * | 2022-08-18 | 2024-02-22 | 阳光电源股份有限公司 | Flying capacitor three-level dc-dc converter, photovoltaic system and control method |
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2020
- 2020-12-10 CN CN202022945408.XU patent/CN213937746U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024037058A1 (en) * | 2022-08-18 | 2024-02-22 | 阳光电源股份有限公司 | Flying capacitor three-level dc-dc converter, photovoltaic system and control method |
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20221102 Address after: Floor 9, Keshida Industrial Park R&D Building, No.7 Road, Gaoxinyuan West District, Guangming New District, Shenzhen, Guangdong 518000 Patentee after: SHENZHEN KSTAR NEW ENERGY Co.,Ltd. Address before: 518000 rooms 401 and 402, 4th floor, building 1, software park, kejizhong 2nd Road, Gaoxin North District, Nanshan District, Shenzhen City, Guangdong Province Patentee before: SHENZHEN KSTAR SCIENCE AND TECHNOLOGY Co.,Ltd. Patentee before: Guangdong Youdian New Energy Technology Co.,Ltd. Patentee before: SHENZHEN KSTAR NEW ENERGY Co.,Ltd. |
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| TR01 | Transfer of patent right |