Direct current charging pile three-phase voltage detection circuit and device

Abstract

The utility model discloses a DC charging pile three-phase voltage detection circuit and device. The DC charging pile three-phase voltage detection circuit comprises an MCU control unit, a single-phase metering IC unit and a to-be-detected unit. Wherein the MCU control unit is in isolated communication with the single-phase metering IC unit through a serial port; the single-phase metering IC unit comprises a first current channel, a second current channel and a first voltage channel which are connected with the unit to be measured, and the first current channel, the second current channel and the first voltage channel are respectively provided with a dropping resistor. According to the direct current charging pile three-phase voltage detection circuit and device provided by the utility model, the detection circuit based on the single-phase metering IC unit can reduce the size of a product, is especially suitable for a direct current charging pile with a small size, makes up for the defects of the existing product, and reduces the structural design difficulty of the whole product.

Description

Technical Field

[0001] The utility model relates to the field of three-phase voltage detection equipment for a DC charging pile, in particular to a three-phase voltage detection circuit and device for a DC charging pile. Background Art

[0002] Currently, most DC charging piles monitor three-phase voltage using an external three-phase meter. This data is then transmitted to an MCU via a 485 communication link. This solution is not only bulky and expensive, but also inconvenient to install for some smaller DC charging piles and increases the complexity of structural design. Utility Model Content

[0003] In order to overcome the shortcomings of the existing technology, a three-phase voltage detection circuit and device for a DC charging pile are proposed.

[0004] A three-phase voltage detection circuit for a DC charging pile includes an MCU control unit, a single-phase metering IC unit, and a unit to be tested; wherein the MCU control unit and the single-phase metering IC unit communicate with each other via a serial port isolation; the single-phase metering IC unit includes a first current channel, a second current channel, and a first voltage channel connected to the unit to be tested, and a voltage dropping resistor is provided on each of the first current channel, the second current channel, and the first voltage channel.

[0005] Preferably, the single-phase metering IC unit includes three differential input ADCs; each of the voltage-dropping resistors has a resistance of 1.2M and an accuracy of 1%.

[0006] Preferably, a crystal oscillator is provided between pin 1 and pin 16 of the single-phase metering IC unit; a first capacitor, a second capacitor, a third capacitor and a fourth capacitor are provided between the single-phase metering IC unit and a preset DC power supply; wherein the first capacitor is connected in parallel with the second capacitor, and the third capacitor is connected in parallel with the fourth capacitor.

[0007] Preferably, each of the voltage-dropping resistors is composed of multiple sub-voltage-dropping resistors with a precision of 1% connected in series, and the total resistance of the multiple sub-voltage-dropping resistors connected in series is 1.2M; a fifth capacitor is connected in parallel between the multiple sub-voltage-dropping resistors connected in series and the ground.

[0008] Preferably, an isolation communication IC unit is further included, which is arranged between the MCU control unit and the single-phase metering IC unit and is used to realize serial port isolation communication between the MCU control unit and the single-phase metering IC unit.

[0009] Preferably, the isolated communication IC unit communicates with the MCU control unit via a UART pin.

[0010] Preferably, a sixth capacitor and a seventh capacitor are arranged in parallel between the isolated communication IC unit and the preset DC power supply; an ESD diode is arranged between the preset DC power supply and the ground, as well as an eighth capacitor and a ninth capacitor connected in parallel with the ESD diode.

[0011] Preferably, the eighth capacitor and the ninth capacitor connected in parallel are connected to the isolated communication IC unit via a first resistor.

[0012] A three-phase voltage detection device for a DC charging pile includes the above-mentioned three-phase voltage detection circuit for the DC charging pile.

[0013] The three-phase voltage detection circuit and device for a DC charging pile provided by this utility model is designed around a single-phase metering IC unit. Dropping resistors are installed in the first, second, and first voltage channels of the single-phase metering IC unit to sample three-phase electricity. The collected data is transmitted to the MCU control unit via serial port isolation communication, enabling three-phase power monitoring while ensuring excellent communication performance and no anomalies. Compared with existing technologies, this detection circuit based on a single-phase metering IC unit can reduce product size, making it particularly suitable for small DC charging piles. This addresses the shortcomings of existing products and reduces the difficulty of overall structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of sampling of a three-phase voltage detection circuit of a DC charging pile in an embodiment of the present utility model;

[0015] Figure 2 This is a schematic diagram of the three-phase voltage detection circuit of a DC charging pile in an embodiment of the present utility model. DETAILED DESCRIPTION

[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Provide a three-phase voltage detection circuit for a DC charging pile, such as Figure 1 、 2 As shown, it includes an MCU control unit, a single-phase metering IC unit and a unit to be tested; wherein the MCU control unit is electrically connected to the single-phase metering IC unit and communicates with it through serial port isolation; the single-phase metering IC unit includes a first current channel, a second current channel and a first voltage channel connected to the unit to be tested, and a voltage drop resistor is respectively provided on the first current channel, the second current channel and the first voltage channel.

[0018] The single-phase metering IC unit uses the RN8209C as an example, but is not limited to this IC model. The single-phase metering IC unit includes three differential input ADCs, each corresponding to the three phases of electricity.

[0019] Specifically, the U46 RN8209C includes a first current channel A, a second current channel B, and a first power channel C, each connected to the unit under test. Current channel A corresponds to pins V1P and V1N, current channel B corresponds to pins V2P and V2N, and voltage channel C corresponds to pins V3P and V3N. All three channels are equipped with a dropper resistor with a total resistance of 1.2MΩ and an accuracy of 1%.

[0020] In one implementation, the voltage-dropping resistor is formed by connecting a plurality of sub-voltage-dropping resistors with a precision of 1% in series, and the total resistance of the plurality of sub-voltage-dropping resistors connected in series is 1.2M. Figure 2 As shown, the sub-drop resistors on the first voltage channel include R339 to R345, the sub-drop resistors on the second current channel include R346 to R353, and the sub-drop resistors on the first current channel include R354 to R360. Preferably, fifth capacitors C428, C431, and C436 are provided in parallel with R345, R353, and R360, respectively. At the same time, the ground terminals of the three channels are also connected to capacitors C437, C444, and C445, and resistors R362, R363, and R364 connected in parallel therewith.

[0021] In one implementation, a crystal oscillator Y6 (HC-49SM 3.579545MHz) is installed between pins 1 and 16 of the single-phase metering IC unit RN8209C. Auxiliary capacitors C429 and C430 are also installed between the crystal oscillator and ground. A first capacitor C432, a second capacitor C433, a third capacitor C434, and a fourth capacitor C435 are installed between the single-phase metering IC unit RN8209C and the preset 3.3V DC power supply. The first capacitor is connected in parallel with the second capacitor, and the third capacitor is connected in parallel with the fourth capacitor.

[0022] Furthermore, the system also includes an isolated communication IC unit U47, which is located between the MCU control unit and the single-phase metering IC unit. This IC unit is used to implement serial communication isolation between the MCU control unit and the single-phase metering IC unit. The isolated communication IC unit uses the CA-IS3621LVW. The isolated communication IC unit's UART pins (UART3_TX and UART3_RX) communicate with the MCU control unit.

[0023] In one implementation, a sixth capacitor C441 and a seventh capacitor C443 are connected in parallel between the isolated communication IC unit CA-IS3621LVW and the preset 3.3V DC DC power supply. An ESD diode SBD52C05L01 is provided between the preset 3.3V DC DC power supply and ground, as well as an eighth capacitor C438 and a ninth capacitor C439 connected in parallel with the ESD diode. Preferably, the parallel eighth and ninth capacitors C438 and C439 are connected to the single-phase metering IC unit via a first resistor R361.

[0024] Understandably, if Figure 2 As shown, in order to ensure the normal operation of the isolated communication IC unit, the working voltage pins VDD, VDDI and the ground pin GNDA of the isolated communication IC unit are also connected to auxiliary components such as C440, C457, C458, R136, etc., which are not repeated here.

[0025] Provided is a three-phase voltage detection device for a DC charging pile, including the above-mentioned three-phase voltage detection circuit for a DC charging pile, which can replace the external three-phase meter in the existing detection method, making the overall product volume smaller and reducing the difficulty of structural design.

[0026] The above is an explanation of the three-phase voltage detection circuit and device of the DC charging pile of the present invention, which is used to help understand the present invention; however, the implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, and simplifications made without departing from the principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A three-phase voltage detection circuit for a DC charging pile, characterized in that: The device comprises an MCU control unit, a single-phase metering IC unit and a unit to be tested; wherein the MCU control unit communicates with the single-phase metering IC unit via a serial port isolation; the single-phase metering IC unit comprises a first current channel, a second current channel and a first voltage channel connected to the unit to be tested, and a voltage drop resistor is respectively provided on the first current channel, the second current channel and the first voltage channel.

2. The three-phase voltage detection circuit of a DC charging pile according to claim 1, characterized in that: The single-phase metering IC unit includes three differential input ADCs; the resistance of each voltage-dropping resistor is 1.2M and the accuracy is 1%.

3. The three-phase voltage detection circuit of a DC charging pile according to claim 2, characterized in that: A crystal oscillator is provided between pins 1 and 16 of the single-phase metering IC unit; a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor are provided between the single-phase metering IC unit and a preset DC power supply; wherein the first capacitor is connected in parallel with the second capacitor, and the third capacitor is connected in parallel with the fourth capacitor.

4. The three-phase voltage detection circuit of a DC charging pile according to claim 3, characterized in that: Each of the voltage-dropping resistors is composed of a plurality of sub-voltage-dropping resistors with a precision of 1% connected in series, and the total resistance of the plurality of sub-voltage-dropping resistors connected in series is 1.2M; a fifth capacitor is connected in parallel between the plurality of sub-voltage-dropping resistors connected in series and the ground.

5. The three-phase voltage detection circuit of a DC charging pile according to any one of claims 1 to 4, characterized in that: It also includes an isolation communication IC unit, which is arranged between the MCU control unit and the single-phase metering IC unit and is used to realize serial port isolation communication between the MCU control unit and the single-phase metering IC unit.

6. The three-phase voltage detection circuit of a DC charging pile according to claim 5, characterized in that: The isolated communication IC unit communicates with the MCU control unit via the UART pin.

7. The three-phase voltage detection circuit of a DC charging pile according to claim 6, characterized in that: A sixth capacitor and a seventh capacitor connected in parallel are arranged between the isolated communication IC unit and the preset DC power supply; an ESD diode is arranged between the preset DC power supply and the ground, as well as an eighth capacitor and a ninth capacitor connected in parallel with the ESD diode.

8. The three-phase voltage detection circuit of a DC charging pile according to claim 7, characterized in that: The eighth capacitor and the ninth capacitor connected in parallel are connected to the isolated communication IC unit via a first resistor.

9. A three-phase voltage detection device for a DC charging pile, characterized in that: The DC charging pile three-phase voltage detection device includes the DC charging pile three-phase voltage detection circuit according to any one of claims 1 to 8.

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