阅读说明：本技术 一种基于串联数字化稳压器的中高压一体化汽车充电系统 (Medium-high voltage integrated automobile charging system based on serial digital voltage stabilizer ) 是由 王建华 范建华 徐鹏飞 李健勋 王嘉伟 王庆园 李鸿儒 张建 李伟 吴雪梅 卢峰 于 2020-05-30 设计创作，主要内容包括：本发明公开了一种基于串联数字化稳压器的中高压一体化汽车充电系统,属于汽车充电技术领域。其结构包括网侧滤波器一端与电网相连,另一端接入输入级交流侧,模组输入级相级联后与数字化稳压器交流侧相连,最后三相的数字化稳压器交流侧剩余端连接到一点,构成星型结构,输入级高压直流侧和数字化稳压器的直流侧分别与中间隔离级的高压直流侧相接,各模组隔离级低压直流侧相并联,与充电桩输入直流侧相接。本发明通过增加调制出的电平数量,来减少电流中的纹波,可大大降低滤波电感的感值,从而减少滤波成本,也有利于提升系统运行效率,也会降低输入级高压模组的数量和开关频率,提升系统效率。(The invention discloses a medium-high voltage integrated automobile charging system based on a series digital voltage stabilizer, and belongs to the technical field of automobile charging. The structure of the high-voltage direct-current charging pile comprises that one end of a network side filter is connected with a power grid, the other end of the network side filter is connected to an input stage alternating-current side, module input stages are connected with a digital voltage stabilizer alternating-current side after being cascaded, the remaining ends of the three-phase digital voltage stabilizer alternating-current side are connected to one point to form a star-shaped structure, the input stage high-voltage direct-current side and the direct-current side of the digital voltage stabilizer are respectively connected with the high-voltage direct-current side of a middle isolation stage, and the low-voltage direct-current sides of. The invention reduces ripple waves in current by increasing the number of modulated levels, can greatly reduce the inductance value of a filter inductor, thereby reducing the filter cost, being beneficial to improving the system operation efficiency, reducing the number of input-stage high-voltage modules and the switching frequency, and improving the system efficiency.)

1. A middle-high voltage integrated automobile charging system based on a series digital voltage stabilizer is characterized by comprising a filter at the side of a power grid, a high-voltage side input stage converter, the digital voltage stabilizer, a middle isolation stage converter and a charging pile module, wherein one end of the filter at the side of the power grid is connected with the power grid, the other end of the filter at the side of the power grid is connected with one end of the input stage alternating current side of a single module, the other end of the input stage AC side of the single module is cascaded with other input stage modules, the remaining end of the AC side of the last input stage module is connected with one end of the AC side of the digital voltage stabilizer, the remaining ends of the AC sides of the digital voltage stabilizers of the last three phases are connected to one point, the DC sides of the input stage high-voltage DC side and the digital voltage stabilizer are respectively connected with the DC side of the middle isolation stage, the low-voltage DC sides of the isolation stages of the modules are connected in parallel and connected with the input DC side of the charging pile, and the three phases are the same.

2. The medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer according to claim 1, characterized in that the digital voltage stabilizer is formed by connecting H-bridge structures with different direct current side voltages VdcN in series, the H-bridge is divided into a left bridge arm and a right bridge arm, each bridge arm has two series connected IGBT modules, each IGBT module consists of an IGBT and an anti-parallel diode, the digital voltage stabilizer is connected in series to an alternating current side structure of the input stage, each input stage has N H-bridge structures connected in series, the direct current side voltage is Udc, the H-bridge direct current side voltage VdcN of the digital voltage stabilizer depends on the number N of the H-bridge structures of the digital voltage stabilizer and the input stage direct current side voltage Udc, and the calculation formula is:

V_dcN＝U_dc/3^N。

3. the medium-high voltage integrated automobile charging system based on the series digital voltage regulators is characterized in that the input stage is composed of an H-bridge module, the H-bridge is divided into a left bridge arm and a right bridge arm, each bridge arm is provided with two series IGBT modules, and each IGBT module is composed of an IGBT and an anti-parallel diode.

4. The medium-high voltage integrated automobile charging system based on the series digital voltage regulators is characterized in that a filter consists of inductors in each phase, one end of each filter inductor is connected with a power grid, the other end of each filter inductor is connected into the middle point of the left bridge arm of an H bridge of an input stage, and the middle point of the right bridge arm is cascaded with the middle point of the left bridge arm of a next module input stage.

5. The medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer as claimed in claim 1, characterized in that the isolation stage is composed of two H-bridge structures and a medium frequency transformer, the two H-bridges are respectively located at the primary side and the secondary side of the medium frequency transformer and are used for converting direct current into alternating current and converting alternating current into direct current, the direct current side of the isolation stage is connected with the direct current side of the input stage, and after passing through the medium frequency transformer, the output sides of the low voltage direct current sides of the isolation stages are connected in parallel to form a low voltage direct current bus.

6. The medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer is characterized in that the charging pile module consists of power devices, a low-voltage direct current bus is connected to the input end of the charging pile, and the direct current conversion output end of the charging pile is connected to an electric automobile to charge the electric automobile.

7. The medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer according to claim 1, characterized in that the conventional automobile charging system can modulate 2 × N +1 levels under the condition that the number of input stage high voltage modules is N, the number of modulation levels added to the digital voltage stabilizer is m, m depends on the number of low voltage modules N of the digital voltage stabilizer and the number of high voltage modules N of the input stage of each phase, and the calculation formula is as follows:

Technical Field

The invention relates to the technical field of medium-high voltage automobile charging systems, in particular to a medium-high voltage integrated automobile charging system based on a series digital voltage stabilizer.

Background

The medium-high voltage integrated automobile charging system is characterized in that the power grid 10kV alternating current firstly passes through the input stage part, the three-phase alternating current of the power grid is changed into high-voltage direct current, the isolation stage part is used for realizing voltage grade conversion and electrical isolation, the high-voltage direct current is changed into low-voltage direct current, finally, the charging of an electric automobile is realized through the charging pile module, and different charging speeds are realized according to different powers of the charging piles. The automobile charging system can charge the electric automobile, can realize the functions of high-voltage direct-current transmission, static reactive compensation, active power filtering and the like, and also improves the power quality of a power grid to a certain extent. However, the input stage of the existing automobile charging system has problems of high difficulty in control, high cost, large volume and the like due to a large number of modules. And the input stage part can produce high-frequency ripple because the level quantity that produces is less in the voltage modulation process, increases system's loss, is unfavorable for electrical equipment's normal operating, though increase module quantity can increase the level quantity, can bring the cost problem.

The traditional method for removing the high-frequency ripple waves comprises the steps of increasing an inductor and an output capacitor for filtering, increasing control to inhibit the ripple waves, and increasing the number of modules to generate more levels.

Disclosure of Invention

Aiming at the defects and the requirements, the invention provides a medium-high voltage integrated automobile charging system based on a series digital voltage stabilizer.

In order to achieve the purpose, the invention provides the following technical scheme: a middle-high voltage integrated automobile charging system based on a series digital voltage stabilizer is characterized by comprising a filter on the power grid side, a high-voltage side input stage converter, a digital voltage stabilizer, a middle isolation stage converter and a charging pile module, wherein one end of the filter on the power grid side is connected with a power grid, the other end of the filter on the power grid side is connected to one end of the input stage alternating current side of a single module, the other end of the input stage alternating current side of the single module is connected with other input stage modules in a cascade mode, the remaining end of the alternating current side of the last input stage module is connected with one end of the alternating current side of the digital voltage stabilizer, the remaining ends of the alternating current sides of the three phases of the digital voltage stabilizer are connected to one point, the direct current sides of the input stage high voltage direct current side and the digital voltage stabilizer are respectively connected with the high voltage direct.

Furthermore, the digital voltage stabilizer is formed by connecting H bridge structures with different direct current side voltages VdcN in series, the H bridge is divided into a left bridge arm and a right bridge arm, each bridge arm is provided with two IGBT modules which are connected in series, each IGBT module is composed of an IGBT and an anti-parallel diode, the digital voltage stabilizer is connected to an alternating current side structure of the input stage in series, each phase of the input stage is provided with N H bridge structures which are connected in series, the direct current side voltage of the input stage is Udc, the H bridge direct current side voltage VdcN of the digital voltage stabilizer depends on the H bridge structure number N of the digital voltage stabilizer and the input stage direct current side voltage Udc, and the calculation formula is as follows:

V_dcN＝U_dc/3^N。

furthermore, the input stage is composed of an H-bridge module, the H-bridge is divided into a left bridge arm and a right bridge arm, each bridge arm is provided with two series-connected IGBT modules, and each IGBT module is composed of an IGBT and an anti-parallel diode.

And furthermore, the filter consists of one inductor of each phase, one end of the filter inductor is connected with a power grid, the other end of the filter inductor is connected into the middle point of the left bridge arm of the H bridge of the input stage, and the middle point of the right bridge arm is cascaded with the middle point of the left bridge arm of the input stage of the next module.

Furthermore, the isolation stage is composed of two H-bridge structures and an intermediate frequency transformer, the two H-bridges are respectively positioned on the primary side and the secondary side of the intermediate frequency transformer and used for converting direct current into alternating current and converting alternating current into direct current, the isolation stage high-voltage direct current side is connected with the input stage direct current side, and after passing through the intermediate frequency transformer, the output ends of the low-voltage direct current sides of the isolation stages are connected in parallel to form a low-voltage direct current bus.

Furthermore, the charging pile module is composed of power devices, a low-voltage direct-current bus is connected to the input end of the charging pile, and the direct-current conversion output end of the charging pile is connected to the electric automobile to charge the electric automobile.

Further, in the conventional automobile charging system, under the condition that the number of input stage high voltage modules is N, 2 × N +1 levels can be modulated, the number of modulation levels after the digital voltage stabilizer is added is m, m depends on the low voltage module N of the digital voltage stabilizer and the number of input stage high voltage modules N of each phase, and the calculation formula is as follows:

compared with the existing automobile charging system, the invention has the advantages and positive effects that: through the level quantity that increases the modulation, reduce the ripple in the electric current, but the inductance value of greatly reduced filter inductance to reduce the filtering cost, also be favorable to promoting system operating efficiency and stability, also can reduce the quantity and the switching frequency of input stage high voltage module, promote system's efficiency.

Drawings

FIG. 1 is a general block diagram of a vehicle charging system;

FIG. 2 is a digitized voltage regulator topology of an embodiment of the invention;

FIG. 3 is a circuit topology diagram of a medium-high voltage integrated automobile charging system based on a series digital voltage stabilizer according to an embodiment of the invention;

FIG. 4 is a modulated voltage diagram of a high-voltage module with two input stage DC side voltages being Udc;

fig. 5 is a modulation voltage diagram of a high voltage module with an input stage dc side voltage of Udc and a digital voltage regulator with a dc side voltage of Udc/3.

Detailed Description

Hereinafter, embodiments of the present invention will be further described with reference to the accompanying drawings.

The structure of the automobile charging system applied by the invention is shown in figure 1 and is divided into a three-stage structure. The input stage converts the 10kV alternating current into high-voltage direct current; the intermediate isolation stage converts the high-voltage direct current into low-voltage direct current and has the function of electrical isolation; the output stage is a charging pile module, and the direct current is subjected to grade change to charge the automobile.

Fig. 2 is a specific topology structure of the digital voltage regulator, which is composed of H-bridge topologies with different voltages on the dc side. The topological structure of the medium-high voltage integrated automobile charging system circuit based on the series digital voltage stabilizer is shown in fig. 3, and the structure of the circuit comprises a filter on the network side, a high-voltage side input stage converter, the digital voltage stabilizer, a middle isolation stage converter and a charging pile module. One end of the network side filter is connected with a power grid, the other end of the network side filter is connected to one end of an input stage alternating current side of a single module, the other end of the input stage alternating current side of the single module is connected with other input stage modules in a cascade mode, the remaining end of the alternating current side of the last input stage module is connected with one end of the alternating current side of the digital voltage stabilizer, the remaining ends of the alternating current sides of the digital voltage stabilizer of three phases are connected to one point, the direct current sides of the input stage high voltage direct current side and the digital voltage stabilizer are respectively connected with the high voltage direct current side of the middle isolation stage, the low voltage direct current sides of the isolation stages.

The input stage is composed of an H-bridge module, the H-bridge is divided into a left bridge arm and a right bridge arm, each bridge arm is provided with two IGBT modules which are connected in series, each IGBT module is composed of an IGBT and an anti-parallel diode, the filter is composed of an inductor of each phase, one end of the filter inductor is connected with a power grid, the other end of the filter inductor is connected to the midpoint of the left bridge arm of the H-bridge of the input stage, and the midpoint of the right bridge arm is connected with the midpoint of the left bridge arm of the;

the isolation stage is composed of two H-bridge structures and an intermediate frequency transformer, the two H-bridges are respectively positioned on the primary side and the secondary side of the intermediate frequency transformer and play the roles of converting direct current into alternating current and converting alternating current into direct current, the isolation stage high-voltage direct current side is connected with the input stage direct current side, and after passing through the intermediate frequency transformer, the output ends of the low-voltage direct current sides of the isolation stages are connected in parallel to form a low-voltage direct current bus. The charging pile module consists of power devices, a low-voltage direct-current bus is connected to the input end of the charging pile, and the direct-current conversion output end of the charging pile is connected to the electric automobile to charge the electric automobile;

the digital voltage stabilizer is formed by connecting H-bridge structures with different direct-current side voltages VdcN in series, the H-bridge is divided into a left bridge arm and a right bridge arm, each bridge arm is provided with two IGBT modules which are connected in series, each IGBT module is composed of an IGBT and an anti-parallel diode, the digital voltage stabilizer is connected to an alternating-current side structure of an input stage in series for application, and each input stage is provided with n H-bridge structuresThe bridge structures are connected in series, the direct current side voltage of the bridge structures is Udc, the H bridge direct current side voltage VdcN of the digital voltage stabilizer can be calculated by the H bridge structure number N of the digital voltage stabilizer and the input stage direct current side voltage Udc, and the calculation formula is V_dcN＝U_dc/3^N. Compared with the traditional automobile charging system, the medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer has one more digital voltage stabilizer per phase, and is used for increasing the number of input-stage modulation levels and reducing the number of input-stage high-voltage modules so as to improve the system performance.

Compared with the traditional automobile charging system, the medium-high voltage integrated automobile charging system based on the series digital voltage stabilizer has the advantage that the modulated level number is increased. In the conventional automobile charging system, 2 × n +1 levels can be modulated under the condition that the number of input high-voltage modules is n, and the digital voltage stabilizer can form more low-voltage modules with different direct-current side voltages, so that more levels can be generated by modulation. The modulation level number after the digital voltage stabilizer is added is m, which can be calculated by a low-voltage module N of the digital voltage stabilizer and a high-voltage module N of the input stage of each phase, specificallyFig. 4 is a graph of modulation voltage of two input stage dc side voltage as Udc high voltage module, fig. 5 is a graph of modulation voltage of a digital voltage regulator with an input stage dc side voltage as Udc high voltage module and a dc side voltage as Udc/3, and fig. 4 and fig. 5 can be obtained by comparing and analyzing, and the number of modulation levels can be improved by adding the digital voltage regulator.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.