阅读说明：本技术 一种电动汽车大功率充电装置用dc/dc变换器 (DC/DC converter for high-power charging device of electric automobile ) 是由 吴晓刚 刘郑心 于渤洋 于 2019-09-29 设计创作，主要内容包括：一种电动汽车大功率充电装置用DC/DC变换器,属于新能源汽车充电系统设计与应用领域。本发明解决了现有充电装置的DC/DC变换器升压拓扑升压比低、末端负载直流侧的电压低、器件应力大,充电速度较慢,难以满足快速充电需求的问题。本发明前端的双电感储能结构相较于单电感结构大幅度提高升压比,特有的后端开关电容结构可以通过电容和二极管使得系统获得更高的电压增益,提升了直流输出侧电压和系统的功率密度。同时,在整流器输出端与负载直流侧中间没有采用隔离型带有变压器DC/DC变换器充当升压结构。本发明适用于大功率汽车充电过程中进行直流变换使用。(A DC/DC converter for a high-power charging device of an electric automobile belongs to the field of design and application of a charging system of a new energy automobile. The charging device solves the problems that the boost topology boost ratio of the DC/DC converter of the existing charging device is low, the voltage of the direct current side of the tail end load is low, the stress of devices is large, the charging speed is slow, and the requirement of quick charging is difficult to meet. Compared with a single inductor structure, the double-inductor energy storage structure at the front end greatly improves the boost ratio, and a special rear-end switch capacitor structure can enable a system to obtain higher voltage gain through a capacitor and a diode, so that the voltage of a direct current output side and the power density of the system are improved. Meanwhile, an isolated DC/DC converter with a transformer is not adopted as a boosting structure between the output end of the rectifier and the direct current side of the load. The invention is suitable for DC conversion in the charging process of high-power automobiles.)

1. A DC/DC converter for a high-power charging device of an electric automobile is characterized by comprising a DC/DC converter main circuit (1);

the DC/DC converter main circuit (1) comprises a front-end boosting structure and a rear-end switch capacitor structure;

the front-end boosting structure comprises an energy storage inductor L1, an energy storage inductor L2, a diode D1, a switching tube S1, a switching tube S2 and a switching tube S3;

the rear-end switch capacitor structure comprises a diode D2, a diode D3, a diode D4, a capacitor C1, a capacitor C2 and a capacitor C3;

one end of the energy storage inductor L1 is connected with the positive terminal of a power supply V1; the other end of the energy storage inductor L1 is connected with the drain of a switch tube S1, and the source of the switch tube S1 is connected with the negative end of a source V1;

the drain electrode of the switch tube S3 is connected with the drain electrode of the switch tube S1, and the source electrode of the switch tube S3 is connected with one end of the energy storage inductor L2;

the anode of the diode D1 is connected with the anode end of the power supply V1, and the cathode of the diode D1 is connected with the source electrode of the switch tube S3;

the other end of the inductor L2 is connected with the drain of the switch tube S2, and the source of the switch tube S2 is connected with the negative end of the power supply V1;

the anode of the diode D2 is connected with the drain of the switch tube S2, the cathode of the diode D2 is connected with the anode of the diode D3, the cathode of the diode D3 is connected with the anode of the diode D4, and the cathode of the diode D4 is the forward power supply signal output end of the DC/DC converter main circuit (1);

one end of the capacitor C1 is connected with the anode of the diode D2, and the other end of the capacitor C1 is connected with the cathode of the diode D3;

the capacitor C2 is connected with the capacitor C3 in series, one end of the capacitor C2 is connected with the negative electrode of the diode D4, and one end of the capacitor C3 is connected with the negative electrode end of the power supply V1;

the cathode of the diode D2 is also connected with the other end of the capacitor C2 and the other end of the capacitor C3;

the negative pole end of the power supply V1 is the negative power supply signal output end of the DC/DC converter main circuit (1).

2. The DC/DC converter for the high-power charging device of the electric automobile according to claim 1, further comprising a DC/DC converter control circuit (2), wherein the DC/DC converter control circuit (2) comprises a protection circuit (201), a DSP system (202), a voltage sensor (203) and a current sensor (204);

the voltage sensor (203) is used for collecting the voltage V2 between the positive power supply signal output end and the negative power supply signal output end of the DC/DC converter main circuit (1) and the output voltage of a power supply V1, and the signal output end of the voltage sensor (203) is connected with the voltage collecting signal input end of the DSP system (202);

the current sensor (204) simultaneously acquires current signals of an inductor L1 and an inductor L2, and a current signal output end of the current sensor (204) is connected with a current acquisition signal input end of the DSP system (202);

a reference voltage/current signal is input into a reference voltage/current signal input end of the DSP system (202); the DSP system (202) compares the received target voltage signal with the output voltage at the direct current side, calculates a duty ratio control signal of the switching tube according to a comparison result by utilizing a PI control algorithm and a closed-loop control method, and outputs the duty ratio control signal of the switching tube obtained by calculation to a protection circuit (201) as a driving signal of the switching tube;

the switch tube driving signal output end of the protection circuit (201) is simultaneously connected with the grid electrode of a switch tube S1, the grid electrode of a switch tube S2 and the grid electrode of a switch tube S3 in the DC/DC converter main circuit (1);

the protection circuit (201) is used for detecting whether the driving signal is over-current or over-voltage, and when the detected driving signal is over-current or over-voltage, the output of the switch driving signal is stopped.

3. The DC/DC converter for the high-power charging device of the electric automobile according to claim 1 or 2, characterized in that the main circuit (1) of the DC/DC converter comprises an inductive charging mode and an inductive discharging mode.

4. The DC/DC converter for the high-power charging device of the electric automobile according to claim 3, wherein the equivalent circuit of the inductive charging mode comprises a switching tube S1, a switching tube S2, a diode D1, an energy storage inductor L1, an energy storage inductor L2, a diode D3, a capacitor C1, a capacitor C2 and a capacitor C3;

one end of the energy storage inductor L1 is connected with the positive terminal of a power supply V1; the other end of the energy storage inductor L1 is connected with the drain of a switch tube S1, and the source of the switch tube S1 is connected with the negative end of a source V1;

the anode of the diode D1 is connected with the anode end of the power supply V1, and the cathode of the diode D1 is connected with one end of the energy storage inductor L2;

the other end of the energy storage inductor L2 is connected with the drain electrode of the switch tube S2, and the source electrode of the switch tube S2 is connected with the negative electrode end of the power supply V1;

one end of the capacitor C1 is connected with the drain electrode of the switch tube S2, and the other end of the capacitor C1 is connected with the cathode of the diode D3;

the anode of the diode D3 is connected with one end of the capacitor C2, and the other end of the capacitor C2 is the positive power supply signal output end of the DC/DC converter main circuit (1);

one end of the capacitor C3 is connected with the anode of the diode D3, and the other end of the capacitor C3 is connected with the cathode end of the power supply V1;

the negative pole end of the power supply V1 is the negative power supply signal output end of the DC/DC converter main circuit (1).

5. The DC/DC converter for the high-power charging device of the electric automobile according to claim 3, wherein the equivalent circuit of the inductor discharge mode comprises a switching tube S3, an energy storage inductor L1, an energy storage inductor L2, a diode D2, a diode D4, a capacitor C1, a capacitor C2 and a capacitor C3;

one end of the energy storage inductor L1 is connected with the positive terminal of a power supply V1; the other end of the energy storage inductor L1 is connected with the drain of the switch tube S3, and the source of the switch tube S3 is connected with one end of the energy storage inductor L2;

the anode of the diode D2 is connected with the other end of the energy storage inductor L2, and the cathode of the diode D2 is connected with one end of the capacitor C2; one end of the capacitor C2 is also connected with one end of the capacitor C3; the other end of the capacitor C3 is connected with the negative electrode end of a power supply V1; the other end of the capacitor C2 is connected with the cathode of the diode D4;

one end of the capacitor C1 is connected with the anode of the diode D2, and the other end of the capacitor C1 is connected with the anode of the diode D4;

the cathode of the diode D4 is the positive power supply signal output end of the DC/DC converter main circuit (1); the negative pole end of the power supply V1 is the negative power supply signal output end of the DC/DC converter main circuit (1).

Technical Field

The invention belongs to the field of design and application of a new energy automobile charging system, and particularly relates to a direct current converter.

Background

The electric automobile uses electric energy to provide power for the automobile for driving, has great promoting significance for relieving the shortage of petroleum energy and reducing the emission of harmful gas, and has a global trend for vigorously developing the electric automobile industry. The charging infrastructure is an important part in the electric automobile industry, and the charging device is an important component of the electric automobile charging infrastructure, and the performance of the charging device can directly influence the development of the electric automobile industry. Therefore, the high-power charging device for the electric automobile, which has complete functions, safety, reliability, good compatibility and high charging speed, has important practical engineering significance for the overall development of the electric automobile industry.

Research on DC/DC converters in current charging devices has focused mainly on isolated and non-isolated topologies. The isolated topology has a large volume, high cost and relatively low efficiency due to the existence of the coupling transformer.

At present, a DC/DC converter in a high-power charging device adopts a non-isolated topology structure, and is directly connected with a rectifier at the front end to convert electric energy of a power grid (alternating current to direct current and direct current to direct current) and charge an electric vehicle. Existing non-isolated topological structures such as boost, buck-boost, etc.) have good dynamic response and high efficiency, but because the circuit structure has fewer energy storage links, the circuit structure provides less energy and has a low voltage boosting ratio when in a working mode of releasing energy to the rear end, and the blind series-parallel inductance increases the energy storage, the volume of the system rises to affect the overall power density, so the existing structure cannot be well adapted to a high-power charging device, and the existing topological structures have large device stress and slow charging speed, and are difficult to meet the purpose of rapid charging.

Disclosure of Invention

The invention aims to solve the problems that the boost topology boost ratio of the DC/DC converter of the existing charging device is low, the voltage of the direct current side of the tail end load is low, the stress of a device is large, the charging speed is slow, and the requirement of quick charging is difficult to meet. A DC/DC converter for a high-power charging device of an electric automobile is provided.

The invention relates to a DC/DC converter for an electric automobile high-power charging device, which comprises a DC/DC converter main circuit 1;

the DC/DC converter main circuit 1 comprises a front-end boosting structure and a rear-end switch capacitor structure;

the front-end boosting structure comprises an energy storage inductor L1, an energy storage inductor L2, a diode D1, a switching tube S1, a switching tube S2 and a switching tube S3;

the rear-end switch capacitor structure comprises a diode D2, a diode D3, a diode D4, a capacitor C1, a capacitor C2 and a capacitor C3;

one end of the energy storage inductor L1 is connected with the positive terminal of a power supply V1; the other end of the energy storage inductor L1 is connected with the drain of a switch tube S1, and the source of the switch tube S1 is connected with the negative end of a source V1;

the drain electrode of the switch tube S3 is connected with the drain electrode of the switch tube S1, and the source electrode of the switch tube S3 is connected with one end of the energy storage inductor L2;

the anode of the diode D1 is connected with the anode end of the power supply V1, and the cathode of the diode D1 is connected with the source electrode of the switch tube S3;

the other end of the inductor L2 is connected with the drain of the switch tube S2, and the source of the switch tube S2 is connected with the negative end of the power supply V1;

the anode of the diode D2 is connected with the drain of the switch tube S2, the cathode of the diode D2 is connected with the anode of the diode D3, the cathode of the diode D3 is connected with the anode of the diode D4, and the cathode of the diode D4 is the positive power signal output end of the DC/DC converter main circuit 1;

one end of the capacitor C1 is connected with the anode of the diode D2, and the other end of the capacitor C1 is connected with the cathode of the diode D3;

the capacitor C2 is connected with the capacitor C3 in series, one end of the capacitor C2 is connected with the negative electrode of the diode D4, and one end of the capacitor C3 is connected with the negative electrode end of the power supply V1;

the cathode of the diode D2 is also connected with the other end of the capacitor C2 and the other end of the capacitor C3;

the negative pole end of the power supply V1 is the negative power supply signal output end of the DC/DC converter main circuit 1.

Further, the control circuit comprises a DC/DC converter control circuit 2, wherein the DC/DC converter control circuit 2 comprises a protection circuit 201, a DSP system 202, a voltage sensor 203 and a current sensor 204;

the voltage sensor 203 collects the output voltage of the DC side of the DC/DC converter main circuit 1 and the output voltage of the power supply V1, and the signal output end of the voltage sensor 203 is connected with the voltage collection signal input end of the DSP system 202;

the current sensor 204 simultaneously acquires current signals of an inductor L1 and an inductor L2, and a current signal output end of the current sensor 204 is connected with a current acquisition signal input end of the DSP system 202;

a target voltage is input to a target voltage signal input end of the DSP system 202; the DSP system 202 compares the received target voltage signal with the output voltage at the dc side, calculates a switching tube duty control signal according to the comparison result by using a PI control algorithm and a closed-loop control method, and outputs the switching tube duty control signal obtained by the calculation to the protection circuit 201 as a switching tube driving signal;

the switch tube driving signal output end of the protection circuit 201 is simultaneously connected with the grid of a switch tube S1, the grid of a switch tube S2 and the grid of a switch tube S3 in the DC/DC converter main circuit 1;

the protection circuit 201 is used for detecting whether the driving signal is over-current or over-voltage, and when the detected driving signal is over-current or over-voltage, the output of the switch driving signal is stopped.

The invention solves the defect of low boost ratio of the traditional boost topology, the dual-inductor energy storage structure at the front end of the boost topology greatly improves the boost ratio compared with a single-inductor structure, and the special rear-end switch capacitor structure can enable the system to obtain higher voltage gain through a capacitor and a diode, thereby improving the voltage at the direct current output side and the power density of the system. Meanwhile, an isolated DC/DC converter with a transformer is not adopted as a boosting structure between the output end of the rectifier and the direct current side of the load, but a non-isolated DC/DC converter is adopted, so that the efficiency of the converter can be improved.

Drawings

FIG. 1 is a schematic diagram of a main circuit of a DC/DC converter for a high-power charging device of an electric vehicle according to the present invention;

FIG. 2 is an equivalent circuit diagram of a DC/DC converter for an electric vehicle high-power charging device in an energy storage inductor charging mode;

FIG. 3 is a diagram showing the energy flow of the DC/DC converter for the high-power charging device of the electric vehicle in the energy storage inductive charging mode, wherein the arrow direction in the diagram is the energy flow direction;

FIG. 4 is an equivalent circuit diagram of the DC/DC converter in the energy storage inductor discharging mode of the DC/DC converter for the high-power charging device of the electric vehicle;

FIG. 5 is a diagram showing energy flow of a DC/DC converter in an energy storage inductor discharging mode of the DC/DC converter for a high-power charging device of an electric vehicle, wherein the direction of an arrow in the diagram is the energy flow direction;

fig. 6 is a schematic block diagram of a main circuit of a DC/DC converter for a high-power charging device of an electric vehicle and a control circuit thereof according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.