阅读说明：本技术 一种一体式直流充电桩 (Integrated direct-current charging pile ) 是由 贺兴家 张江林 岳小锋 庄慧敏 谢晓娜 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种一体式直流充电桩,主要解决现有直流充电桩原理图绘制和PCB板制作难度大且难以同时满足实时控制功能与事务分析、处理功能的问题。该直流充电桩包括通过RS485通信电路相连的主控制模块和功率控制模块,与主控制模块相连的人机交互显示模块、读写卡模块、电能计量模块、充电接口模块及充电监控模块,以及与功率控制模块相连的三相交流输入电源。通过上述设计,本发明将直流充电桩控制系统划分为两层结构,主控制模块实现人机交互和联网监控功能,主控制模块中控制器采用ARM处理器；功率控制模块实现充电控制和故障保护功能,其中的控制器采用DSP处理器。这样的设计使得PCB板的制作难度降低,能够满足实时控制功能与事务分析、处理功能。(The invention discloses an integrated direct current charging pile, which mainly solves the problems that the drawing of a schematic diagram and the manufacturing of a PCB (printed circuit board) of the conventional direct current charging pile are difficult, and the real-time control function and the transaction analysis and processing function are difficult to simultaneously meet. The direct-current charging pile comprises a main control module and a power control module which are connected through an RS485 communication circuit, a human-computer interaction display module, a read-write card module, an electric energy metering module, a charging interface module and a charging monitoring module which are connected with the main control module, and a three-phase alternating-current input power supply which is connected with the power control module. Through the design, the direct-current charging pile control system is divided into a two-layer structure, the main control module realizes the functions of man-machine interaction and networking monitoring, and the controller in the main control module adopts an ARM processor; the power control module realizes the functions of charging control and fault protection, and a DSP processor is adopted as a controller. The design reduces the manufacturing difficulty of the PCB and can meet the real-time control function and the transaction analysis and processing function.)

1. An integrated direct-current charging pile is characterized by comprising a main control module and a power control module which are connected through an RS485 communication circuit, a human-computer interaction display module, a read-write card module, an electric energy metering module, a charging interface module and a charging monitoring module which are connected with the main control module, and a three-phase alternating-current input power supply which is connected with the power control module; the charging interface module is also connected with the power control module; the power control module comprises a power controller, a three-phase PFC circuit, a high-frequency DC-DC circuit and an auxiliary power supply, wherein the three-phase PFC circuit, the high-frequency DC-DC circuit and the auxiliary power supply are connected with the power controller; the output end of the three-phase alternating current input power supply is connected with the input ends of the three-phase PFC circuit and the auxiliary power supply; the charging interface circuit is connected with the output end of the high-frequency DC-DC circuit and the power controller.

2. The integrated direct-current charging pile according to claim 1, wherein an EMI filter circuit and a soft start circuit are connected to the three-phase alternating-current input power supply end; the EMI filter circuit consists of an X capacitor, a Y capacitor, a discharge resistor and a common mode/differential mode inductor; the X capacitor is connected to two ends of the power line and is used for eliminating differential mode interference; the Y capacitor is connected to two ends of the power line and the ground line to eliminate common mode interference; the discharge resistor is used for discharging the charge on the capacitor; the common mode/differential mode inductance converts high frequency interference into thermal energy of the ferrite for suppressing interference signals.

3. The integrated direct-current charging pile according to claim 2, characterized in that the soft start circuit consists of current limiting resistors and relays K1 and K2; the current-limiting resistor is connected in series with B, C two-phase power lines, and the relays K1 and K2 are respectively arranged on B, C two-phase power lines.

4. The integrated direct-current charging pile according to claim 3, wherein the three-phase PFC circuit adopts a three-phase three-level VIENNA rectifying circuit.

5. The integrated direct-current charging pile according to claim 4, wherein the high-frequency DC-DC circuit is a three-level full-bridge LLC resonant circuit.

Technical Field

The invention belongs to the technical field of charging piles, and particularly relates to an integrated direct-current charging pile.

Background

With the environmental protection idea going deep into the mind, more and more people tend to select clean and environmental electric vehicles, and the electric vehicle charging pile industry is also facing new development wave. In the early stage, due to the fact that production standards of different manufacturers are inconsistent, products of charging piles are complex, universality of the charging piles is poor, and popularization of the charging piles is limited.

The direct current fills electric pile and adopts the conduction formula technique of charging, provides quick charging service for electric automobile. Due to the fact that the construction of charging pile infrastructures is not matched with the holding capacity of the new energy automobile, nearly 2000 ten thousand gaps are reserved when the construction of charging piles according to the pile ratio of 3:1 in 2030 is predicted. In order to meet the rapidly growing requirements of people and promote the construction of charging infrastructures in China, the direct current charging pile equipment which is convenient to operate, safe, reliable, low in cost, wide in distribution and easy to manage is designed, and is urgent.

The existing direct current charging pile adopts a basic single control panel, all functional modules are required to be integrated together, the difficulty of drawing a schematic diagram and manufacturing a PCB (printed circuit board) in the later stage can be increased, and the real-time control function and the transaction analysis and processing function are difficult to simultaneously meet.

Disclosure of Invention

The invention aims to provide an integrated direct-current charging pile, which mainly solves the problems that the drawing of a schematic diagram of the existing direct-current charging pile and the manufacturing of a PCB are difficult, and the real-time control function and the transaction analysis and processing function are difficult to meet simultaneously.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an integrated direct-current charging pile comprises a main control module and a power control module which are connected through an RS485 communication circuit, a human-computer interaction display module, a read-write card module, an electric energy metering module, a charging interface module and a charging monitoring module which are connected with the main control module, and a three-phase alternating-current input power supply which is connected with the power control module; the charging interface module is also connected with the power control module; the power control module comprises a power controller, a three-phase PFC circuit, a high-frequency DC-DC circuit and an auxiliary power supply, wherein the three-phase PFC circuit, the high-frequency DC-DC circuit and the auxiliary power supply are connected with the power controller; the output end of the three-phase alternating current input power supply is connected with the input ends of the three-phase PFC circuit and the auxiliary power supply; the charging interface circuit is connected with the output end of the high-frequency DC-DC circuit and the power controller.

Further, in the present invention, the three-phase ac input power terminal is connected to an EMI filter circuit and a soft start circuit; the EMI filter circuit consists of an X capacitor, a Y capacitor, a discharge resistor and a common mode/differential mode inductor; the X capacitor is connected to two ends of the power line and is used for eliminating differential mode interference; the Y capacitor is connected to two ends of the power line and the ground line to eliminate common mode interference; the discharge resistor is used for discharging the charge on the capacitor; the common mode/differential mode inductance converts high frequency interference into thermal energy of the ferrite for suppressing interference signals.

Further, in the invention, the soft start circuit is composed of a current limiting resistor and relays K1 and K2; the current-limiting resistor is connected in series with B, C two-phase power lines, and the relays K1 and K2 are respectively arranged on B, C two-phase power lines.

Further, in the present invention, the three-phase PFC circuit uses a three-phase three-level VIENNA rectification circuit.

Further, in the invention, the high-frequency DC-DC circuit adopts a three-level full-bridge LLC resonant circuit.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, a direct current charging pile control system is divided into a two-layer structure, a main control module realizes the functions of human-computer interaction and networking monitoring, and a controller in the main control module adopts an ARM processor; the power control module realizes the functions of charging control and fault protection, and a DSP processor is adopted as a controller. The design reduces the manufacturing difficulty of the PCB, and the two control circuits can work in a cooperative manner, so that the real-time control function and the transaction analysis and processing function can be met.

(2) In the invention, the three-phase PFC circuit adopts a three-phase three-level VIENNA rectifying circuit, has the advantages of simple circuit structure, easy realization of digital control, small harmonic distortion rate of input current, good current sinusoidal characteristic, high power factor and the like, is suitable for a high-power rectifying circuit with higher voltage, and has less influence on a power grid.

(3) In the invention, in order to realize the purpose of outputting wide-range adjustable direct current, a part of circuits of the high-frequency DC-DC circuit adopts a three-level full-bridge LLC resonant converter. The LLC resonant converter can realize ZVS (zero voltage switching) due to the primary side power switching tube, and the secondary side rectifier diode can realize ZCS (zero current switching), so that the switching loss can be reduced, and the working efficiency is improved.

Drawings

Fig. 1 is an overall schematic block diagram of the present invention.

FIG. 2 is a schematic diagram of an EMI filter circuit and a soft start circuit according to the present invention.

FIG. 3 is a schematic diagram of a power circuit of the main control module of the present invention.

FIG. 4 is a schematic diagram of a JTAG download circuit of the main control module of the present invention.

FIG. 5 is a schematic diagram of a BOOT BOOT circuit of the main control module of the present invention.

Fig. 6 is a schematic diagram of a CAN communication interface circuit according to the present invention.

Fig. 7 is a schematic diagram of an RS485 communication interface circuit in the invention.

Fig. 8 is a schematic diagram of a VIENNA rectifier circuit of the present invention.

Fig. 9 is a schematic diagram of a VIENNA rectifier circuit with reverse series connection of power switching tubes.

Fig. 10 is a schematic diagram of a three-level full-bridge LLC circuit in accordance with the present invention.

Detailed Description

The present invention will be further described with reference to the following description and examples, which include but are not limited to the following examples.

Examples

As shown in fig. 1, the integrated dc charging pile disclosed by the present invention comprises a main control module and a power control module connected through an RS485 communication circuit, a human-computer interaction display module, a read-write card module, an electric energy metering module, a charging interface module and a charging monitoring module connected to the main control module, and a three-phase ac input power source connected to the power control module; and the charging interface module is also connected with the power control module. The main control module realizes the communication functions of controlling the power supply and the indicator light and the parts such as the touch screen, the card reader-writer, the networking module, the ammeter module and the like. And the power control board is used for realizing the communication functions of the insulation monitoring module and the charging interface module, and the functions of input and output sampling, contactor control, waveform modulation control of a switching tube, emergency stop control, starting control and the like. The core chip of the main control module adopts a 32-bit microcontroller STM32F407ZGT6 based on an ARM Cortex-M4 kernel of Italian semiconductor corporation.

The main control module circuit includes a minimum system circuit and a peripheral circuit. The minimal system circuit of the STM32F407ZGT6 chip includes a power supply circuit, a reset circuit, a crystal oscillator circuit, and a download circuit. The STM32F407ZGT6 chip has an operating voltage of 1.8V to 3.6V, and is generally powered by 3.3V in order to protect the chip from being burnt, and an input 5V power supply is converted into 3.3V by using a model ASM1117-3.3V chip, as shown in FIG. 3.

The STM32F407ZGT6 chip has a main frequency of 168MHz and is realized by a crystal oscillator and an on-chip PLL together. An 8MHz crystal oscillator is adopted as a signal source of an external high-speed clock, an RTC clock is driven by an external crystal oscillator of 32.768kHz, and a program download interface is selected as a JTAG mode, as shown in figure 4. The chip enable circuit is provided by the BOOT0 and BOOT1 pins, as shown in FIG. 5. When BOOT0 is 0 and BOOT1 is X, starting the internal FLASH; when the BOOT0 is 1 and the BOOT1 is 0, starting a system memory; when BOOT0 is 1 and BOOT1 is 1, SRAM is activated.

The CAN bus is a bus standard for vehicles, and the international standard defines ISO11898 and ISO 11519-2. The former is a high-speed communication standard with a transmission rate of 125kbps to 1Mbps, and the latter is a low-speed communication standard with a rate of 125 kbps. The main control module and the battery management system of the electric automobile perform data interaction and transmit instruction signals through a CAN bus, and the principle of a circuit communication interface is shown in FIG. 6.

The application selects the CAN bus of the ISO11898 standard. The level on its bus is determined by the potential difference of CAN H and CAN L. When the level difference is 2V, the bus is at logic level 0, and when the level difference is 0V, the bus is at logic level 1.

Main control module and electric energy metering module, the monitoring module that charges, reading and writing card module and the mutual display module that helps, all adopt RS485 communication standard between main control module and the power control module in this application. The RS485 bus has the characteristics of strong anti-interference capability, long transmission distance and the like. RS485 as data transceiver, and supply voltage is 3.3V, can carry out data transmission at the rate of 10Mbps, and the output has short-circuit protection function, ensures data transmission's accuracy, as shown in figure 7.

The power control module comprises a power controller, a three-phase PFC circuit, a high-frequency DC-DC circuit and an auxiliary power supply, wherein the three-phase PFC circuit, the high-frequency DC-DC circuit and the auxiliary power supply are connected with the power controller; the output end of the three-phase alternating current input power supply is connected with the input ends of the three-phase PFC circuit and the auxiliary power supply; the charging interface circuit is connected with the output end of the high-frequency DC-DC circuit and the power controller. The auxiliary power supply is used for working power utilization of the automobile battery management system, charging interface interlocking is realized in the charging process, and the auxiliary power supply is automatically disconnected after charging is finished; and adjusting the charging state according to the acquired information of the battery management system of the electric automobile, and finishing the charging target. The core chip of the power controller adopts a digital processor TMS320F28335, and the power controller has the advantages of higher performance, lower cost and smaller power consumption. And the external device integration level is high, the data and program storage capacity is large, and the A/D conversion is more accurate and faster. A 32-bit floating-point processing unit with a high-speed processing capability of 150 MHz; 18 paths of PWM output, 6 paths of PWM output (HRPWM) with higher precision; 12-bit 16-channel ADC. The chip adopts floating point operation, which is convenient for users to write control algorithm quickly, simplifies software development and reduces development time and cost.

The charging monitoring module is used for connecting the direct current charging pile with the charging pile system. The monitoring module uploads the running state of the direct current charging pile to the processing center through the communication interface and is controlled and monitored by the background.

As shown in fig. 2, in the present invention, the three-phase ac input power terminal is connected with an EMI filter circuit and a soft start circuit; the EMI filter circuit consists of an X capacitor, a Y capacitor, a discharge resistor and a common mode/differential mode inductor; the X capacitor is connected to two ends of the power line and is used for eliminating differential mode interference; the Y capacitor is connected to two ends of the power line and the ground line to eliminate common mode interference; the discharge resistor is used for discharging the charge on the capacitor; the common mode/differential mode inductance converts high frequency interference into thermal energy of the ferrite for suppressing interference signals. In engineering, the X capacitor and the Y capacitor are collectively called as safety capacitors, so that electric shock cannot be caused even if the capacitors fail, and the safety factor is high. In this embodiment, the capacitance X is 3.3uF, the capacitance Y is 0.047uF, the withstand voltage is 275V, and the discharge resistance R is a metal film resistance of 200k Ω. Meanwhile, piezoresistors with the model number of 7D471K are respectively connected to two ends of a three-phase input alternating current phase line and used for restraining surge current. The common mode inductor selects a three-phase horizontal common mode filter inductor, and the choke coil has an inductance value of 1.3mH and allows the passing current to be 15A. Since the differential-mode inductance value is usually small and only 10-50 uH, the leakage inductance of the common-mode inductance is selected to replace the leakage inductance, so that the design is simplified and the cost is saved.

In the invention, the soft start circuit is composed of a current limiting resistor and relays K1 and K2. For simplicity of design, a current limiting resistor is connected in series with the two-phase power line at B, C. When the power circuit starts to work, when the soft start signal of the power controller is at a high level, the coil does not act, the relay is in a normally open state, and the input current is limited by the resistor and then charges the output capacitor of the preceding stage circuit. When the power controller detects that the voltage of the output capacitor of the preceding stage circuit reaches a certain value, the soft start signal is changed from high level to low level, the electric appliance is closed after the coil is electrified, the current-limiting resistor is short-circuited, and the main circuit starts to work normally.

In order to meet the requirement of outputting high power quality, the three-phase PFC circuit selects a three-phase three-level VIENNA rectifying circuit. As shown in FIG. 8, u_a、u_b、u_cFor three-phase AC input voltage i_a、i_b、i_cThree-phase AC input current, point O being the power supply midpoint, L_a、L_b、L_cFor boost filter inductance, D_a1、D_a2、D_b1、D_b2、D_c1、D_c2For fast recovery diodes, C₁、C₂For outputting filter capacitors, S_a、S_b、S_cIs a bidirectional power switch tube group.

The power switch tube (MOSFET) group has two structures. One is composed of power switch tubes connected in series in reverse direction, and the other is composed of bridge diodes and switch tubes. Both structures can realize bidirectional current flow. In this embodiment, the power switch tube group structure shown in fig. 9 is adopted, so that the number of fast recovery diodes can be reduced, and the cost can be saved.

The output voltage value of the DC side of the three-phase three-level VIENNA rectifier is determined by the input current and the power switch tube. When the bidirectional switch tube group is regularly controlled, the input voltage and current at the alternating current side are in the same phase, and the power factor is 1. Each phase is provided with an upper quick recovery diode and a lower quick recovery diode to realize follow current conduction, and energy can only flow in a single direction due to the single-phase conduction of the diodes, so that the three-phase VIENNA rectifier only works in a rectification state.

When the switching tube is turned off, the three-phase alternating current input charges the inductor, and the load is powered by the output capacitor; when the switch tube is conducted, the load is powered by the power supply and the inductor together, and the output capacitor is charged at the same time. The circuit topology is also called a three-level circuit because the working state of the switching tube changes, so that the voltage of the M point is clamped to three level states of 0 and +/-U/2, wherein U is the output voltage of the direct current side.

In the invention, the high-frequency DC-DC circuit adopts a three-level full-bridge LLC resonant circuit. As shown in fig. 10.

Wherein, V_inRepresenting a preceding stage direct current input; c_in1、C_in2Is an input capacitance, D₉～D₁₂The clamping diode is used for enabling the voltage borne by each switching tube to be half of the input voltage; c_s1、C_s1The flying capacitor is used for decoupling the switching tubes of the same bridge arm, so that mutual influence is avoided in the working process; q₁～Q₈To switch tubes, D₁～D₈And C₁～C₈A body diode and a junction capacitor of the switching tube respectively; resonant inductor L_rResonant capacitor C_rAnd an excitation inductance L_mTogether forming a resonant network, N₁、N₂The number of turns of the primary side and the secondary side of the high-frequency transformer are respectively; d_R1～D_R4Is a secondary side rectifying diode and an output capacitor C₀Output load R_LForming a rectifier network.

When the direct current charging pile is used for charging, a user connects a charging interface of the direct current charging pile with an electric automobile, then card swiping operation is carried out in a radio frequency card reading and writing area on the pile body, and the main control system identifies and reads effective information of the user. A guidance operation interface appears in the area of the man-machine interaction display module, and a user can determine a charging mode and pay according to prompt information. In the charging process, the electric energy metering module records charging information in real time, and the charging monitoring module dynamically monitors the process. When an emergency occurs, the emergency stop button designed at the charging monitoring module can be operated to cut off the three-phase alternating current input power supply, so that the equipment and personal safety are guaranteed.

Through the design, the direct-current charging pile control system is divided into a two-layer structure, the main control module realizes the functions of man-machine interaction and networking monitoring, and the controller in the main control module adopts an ARM processor; the power control module realizes the functions of charging control and fault protection, and a DSP processor is adopted as a controller. The design reduces the manufacturing difficulty of the PCB, and the two control circuits can work in a cooperative manner, so that the real-time control function and the transaction analysis and processing function can be met.

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or changes made within the spirit and scope of the main design of the present invention, which still solve the technical problems consistent with the present invention, should be included in the scope of the present invention.