Charging pile isolation type DC bus high-voltage detection circuit

Abstract

The utility model provides a charging pile isolation type direct current bus high-voltage detection circuit, which comprises a differential amplification unit, an isolation amplification unit, a filtering shaping unit, a voltage-stabilized power supply unit and a main control unit, and is characterized in that the input end of the differential amplification unit is electrically connected with the output end of a charging module of a charging pile; the DC bus high-voltage signal conversion module is used for converting DC bus high-voltage signals into primary DC voltage signals; the input end of the isolation amplification unit is electrically connected with the output end of the differential amplification unit, and the isolation amplification unit is used for isolating and transmitting the primary direct-current voltage signal and amplifying and reducing the primary direct-current voltage signal into a secondary direct-current voltage signal in proportion; the input end of the filtering and shaping unit is electrically connected with the output end of the isolation amplification unit, the output end of the filtering and shaping unit is electrically connected with the input end of the main control unit, and the filtering and shaping unit is used for filtering and shaping the secondary direct-current voltage signal and sending the signal to the main control unit for data processing; through the differential amplification unit, the isolation amplification unit, the filtering shaping unit and the voltage stabilizing power supply unit, accurate, safe and stable detection of 500V direct current bus high-voltage signals output by the charging pile is realized, the signal processing accuracy and the circuit reliability are improved, and powerful support is provided for real-time monitoring and management of the charging pile.

Description

Technical Field

[0001] The utility model relates to the technical field of high-voltage detection of a DC busbar of a charging pile, and in particular to an isolated DC busbar high-voltage detection circuit of a charging pile. Background Art

[0002] With the rapid development of electric vehicles, DC charging piles, as essential infrastructure for the electric vehicle industry, are receiving increasing attention from central and local governments, leading to increasingly stringent performance requirements. The monitoring unit is the primary control unit of the charging pile power system. The output DC bus high-voltage detection circuit is a crucial component of the entire monitoring unit. The accuracy and stability of the detection signal directly impacts the safe and efficient operation of the charging pile.

[0003] A multiplexed switching DC high-voltage isolation sampling device with publication number CN215415604U relates to a multiplexed switching DC high-voltage isolation sampling device for a DC energy storage charging pile. The device includes an A / D conversion module, several voltage divider sampling modules and several drive modules; the A / D conversion module includes a first input end and a second input end; each pair of high-voltage positive bus and high-voltage negative bus is configured with a voltage divider sampling module and a drive module; the voltage divider sampling module includes a voltage divider resistor and a sampling resistor; the drive module includes a drive power supply, a first switch and a second switch, and the normal states of the first switch and the second switch are both disconnected; the voltage divider resistor and the sampling resistor are connected in series between the high-voltage positive bus and the high-voltage negative bus in sequence, the connection point between the voltage divider resistor and the sampling resistor is connected to the first input end via the first switch, and the connection point between the sampling resistor and the high-voltage negative bus is connected to the second input end via the second switch.

[0004] Since the DC bus high-voltage signal reaches 300V-750V, it participates in the insulation detection and charging process control functions of the charging pile. Therefore, the DC bus high-voltage detection signal needs to be converted into a voltage analog signal through isolation and sent to the monitoring unit's microcontroller for processing. The existing DC high-voltage isolation sampling device has poor detection signal accuracy and stability, which affects the safe and efficient operation of the charging pile. Utility Model Content

[0005] In view of this, the utility model proposes an isolated DC bus high-voltage detection circuit for a charging pile, which has strong isolation performance and high accuracy and stability of the detection signal, thereby effectively ensuring the safe and efficient operation of the charging pile.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a charging pile isolated DC bus high voltage detection circuit, including a differential amplifier unit, an isolation amplifier unit, a filter shaping unit, and a main control unit, wherein:

[0007] The input end of the differential amplifier unit is electrically connected to the output end of the charging module of the charging pile, and is used to convert the DC bus high voltage signal into a primary DC voltage signal;

[0008] The input end of the isolation amplifier unit is electrically connected to the output end of the differential amplifier unit, and is used to isolate, transmit, and proportionally amplify the primary DC voltage signal to restore it into a secondary DC voltage signal;

[0009] The input end of the filtering and shaping unit is electrically connected to the output end of the isolation amplifier unit, and the output end of the filtering and shaping unit is electrically connected to the input end of the main control unit, for filtering and shaping the secondary DC voltage signal and sending it to the main control unit for data processing.

[0010] On the basis of the above technical solution, preferably, the differential amplification unit includes resistors R1, R2, R3, R4, R5, R6, R7, capacitors C1, C2, C3 and an operational amplifier U1A, wherein the positive electrode of the output end of the charging module of the charging pile is electrically connected to the resistor R1 and one end of the resistor R4, respectively, the negative electrode of the output end of the charging module of the charging pile is electrically connected to the other end of the resistor R1 and one end of the resistor R2, respectively, the other end of the resistor R4 is electrically connected to the resistor R5, and the other end of the resistor R5 is electrically connected to the resistor R6, the capacitor C1 and the operational amplifier U1. A positive input terminal of the operational amplifier U1A is electrically connected, the other end of the resistor R6 and the capacitor C1 are commonly connected to the primary reference power supply, the other end of the resistor R2 is electrically connected to the resistor R3, the other end of the resistor R3 is electrically connected to the inverting input terminal of the operational amplifier U1A, the resistor R7 and one end of the capacitor C2 respectively, the other ends of the capacitor C2 and the resistor R7 are electrically connected to the output terminal of the operational amplifier U1A, the power supply terminal of the operational amplifier U1A is electrically connected to the capacitor C3 and the primary power supply terminal respectively, and the other end of the capacitor C3 and the ground terminal of the operational amplifier U1A are connected to the primary working ground.

[0011] On the basis of the above technical solution, preferably, the isolation amplification unit includes resistors R8, R9, R10, R11, R12, R13, capacitors C4, C5, C6, C7, C8, an operational amplifier U1B, U3A and a photoelectric coupler U2, wherein one end of the resistor R8 is electrically connected to the output end of the operational amplifier U1A, the other end of the resistor R8 is electrically connected to the resistor R9 and the capacitor C4, the other end of the resistor R9 is electrically connected to the capacitor C5, the capacitor C6, the inverting input end of the operational amplifier U1B and the negative electrode of the first output photodiode of the photoelectric coupler U2, the positive electrode of the first output photodiode, the capacitor C4 and the other end of the capacitor C5, and the non-inverting input end of the operational amplifier U1B are connected to the primary working ground, and the other end of the capacitor C6 is electrically connected to the output end of the operational amplifier U1B and the resistor R11. The other end of the resistor R11 is electrically connected to the cathode of the input photodiode of the optocoupler U2, the anode of the input photodiode of the optocoupler U2 is electrically connected to the resistor R10, the other end of the resistor R10 is connected to the primary power supply, the cathode of the second output photodiode of the optocoupler U2 is electrically connected to the inverting input terminal of the operational amplifier U3A, the resistor R12 and the capacitor C7 respectively, the other end of the resistor R12 is electrically connected to the resistor R13, the anode of the second output photodiode of the optocoupler U2 is electrically connected to the non-inverting input terminal and the ground terminal of the operational amplifier U3A respectively, the other ends of the capacitor C7 and the resistor R13 are electrically connected to the output terminal of the operational amplifier U3A, the power supply terminal of the operational amplifier U3A is electrically connected to the capacitor C8 and the secondary power supply terminal respectively, and the other end of the capacitor C8 is connected to the secondary working ground.

[0012] On the basis of the above technical solution, preferably, the filtering and shaping unit includes resistors R14, R15, capacitor C9 and operational amplifier U3B, wherein the resistor R14 is electrically connected to the output end of the operational amplifier U3A, the other end of the resistor R14 is electrically connected to the capacitor C9 and the non-inverting input end of the operational amplifier U3B, respectively, the other end of the capacitor C9 is connected to the secondary working ground, the inverting input end of the operational amplifier U3B is electrically connected to the output end of the operational amplifier U3B and the resistor R15, and the other end of the resistor R15 is electrically connected to the main control unit.

[0013] On the basis of the above technical solution, preferably, it also includes a voltage-stabilized power supply unit, the input end of the voltage-stabilized power supply unit is electrically connected to the external power supply, and the output and input ends of the voltage-stabilized power supply unit are electrically connected to the power supply ends of the differential amplifier unit, the isolation amplifier unit and the filtering and shaping unit, respectively, for providing primary and secondary power supplies.

[0014] On the basis of the above technical solution, preferably, the voltage-stabilized power supply unit includes capacitors C10, C11, C12, C13, C14, C15, an isolated power supply U4 and a voltage-stabilized reference source U5, wherein the positive electrode of the input end of the isolated power supply U4 is electrically connected to the capacitor C11, the capacitor C10 and the external power supply respectively, the other ends of the capacitors C10 and C11 are respectively connected to the negative electrode of the input end of the isolated power supply U4 and the secondary working ground, the positive electrode of the output end of the isolated power supply U4 is respectively connected to the resistor R16, the capacitor C11 and the external power supply respectively, C12, capacitor C13, capacitor C14, the input end of the voltage-stabilized reference source U5 and the first voltage output end of the voltage-stabilized power supply unit are electrically connected, the negative electrode of the output end of the isolation power supply U4 is respectively connected to the other end of the resistor R16, the other end of the capacitor C12, the other end of the capacitor C13, the other end of the capacitor C14, capacitor C15 and the ground end of the voltage-stabilized reference source U5 to the primary working ground, and the output end of the voltage-stabilized reference source U5 is respectively electrically connected to the second voltage output end of the voltage-stabilized power supply unit and the other end of the capacitor C15.

[0015] On the basis of the above technical solution, preferably, the input voltage of the voltage-stabilized power supply unit is +5V, the first voltage output voltage of the voltage-stabilized power supply unit is a +5V DC voltage-stabilized power supply, the second voltage output voltage of the voltage-stabilized power supply unit is a +2.5V reference power supply, the first voltage output of the voltage-stabilized power supply unit is electrically connected to the power supply end of the differential amplifier unit and the power supply end of the primary power supply of the isolation amplifier unit, the second voltage output of the voltage-stabilized power supply unit is electrically connected to the reference power supply end of the differential amplifier unit, and the input of the voltage-stabilized power supply unit is electrically connected to the secondary power supply of the isolation amplifier unit and the power supply end of the filtering and shaping unit.

[0016] On the basis of the above technical solution, preferably, the chip model of the operational amplifier U1A is OPA2234EA.

[0017] On the basis of the above technical solution, preferably, the operational ratio of the operational amplifier U1A is 1:0.0051, converting the 500V DC bus high voltage signal into a 2.55V primary DC voltage signal.

[0018] On the basis of the above technical solution, preferably, the chip model of the photoelectric coupler U2 is HCNR201.

[0019] The isolated DC bus high-voltage detection circuit for charging piles of the present invention has the following advantages over the prior art:

[0020] (1) The DC bus high voltage signal output by the charging module of the charging pile is shaped and amplified by the differential amplifier unit, and then sent to the isolation amplifier unit for isolated and accurate transmission of the primary voltage signal and proportional amplification and restoration. Finally, it is filtered and shaped by the filter and shaping unit, and the DC bus high voltage analog signal is sent to the main control unit for data processing, thereby achieving accurate, safe and stable detection of the DC bus high voltage signal output by the charging pile, and improving the accuracy of signal processing and the reliability of the circuit;

[0021] (2) The 2.55V primary DC voltage signal output by the differential amplifier unit is accurately transmitted in a 1:1 ratio isolation and amplified proportionally to restore it to a 2.55V secondary DC voltage signal, so that the input and output voltage signals remain completely consistent, with high linearity and stable gain characteristics; at the same time, the capacitor C6 and the operational amplifier U1B form an integration circuit, and the photoelectric coupler HCNR201 forms an input and output feedback adjustment circuit, so that the input and output linearity are closely matched, thereby improving the accuracy of the output voltage signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a principle block diagram of the isolated DC bus high-voltage detection circuit for a charging pile of the present utility model;

[0024] Figure 2 This is a circuit diagram of the differential amplifier unit of the isolated DC bus high-voltage detection circuit for the charging pile of the present utility model;

[0025] Figure 3 This is a circuit diagram of the isolation amplifier unit of the isolated DC bus high-voltage detection circuit for the charging pile of the present invention;

[0026] Figure 4 This is a circuit diagram of the filter and shaping unit of the isolated DC bus high-voltage detection circuit of the charging pile of the present utility model;

[0027] Figure 5 This is a circuit diagram of the voltage-stabilized power supply unit of the isolated DC bus high-voltage detection circuit for a charging pile in the present utility model. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, the utility model is an isolated DC bus high-voltage detection circuit for a charging pile, comprising a differential amplifier unit 1, an isolation amplifier unit 2, a filter and shaping unit 3 and a main control unit 4, wherein the input end of the differential amplifier unit 1 is electrically connected to the output end of the charging module of the charging pile, for converting the DC bus high-voltage signal into a primary DC voltage signal; the input end of the isolation amplifier unit 2 is electrically connected to the output end of the differential amplifier unit 1, for isolating and transmitting the primary DC voltage signal and amplifying it proportionally to restore it into a secondary DC voltage signal; the input end of the filter and shaping unit 3 is electrically connected to the output end of the isolation amplifier unit 2, and the output end of the filter and shaping unit 3 is electrically connected to the input end of the main control unit 4, for filtering and shaping the secondary DC voltage signal, and sending it to the main control unit 4 for data processing.

[0030] In addition, it also includes a voltage-stabilized power supply unit 5, the input end of which is electrically connected to an external power supply, and the output and input ends of the voltage-stabilized power supply unit 5 are electrically connected to the power supply ends of the differential amplifier unit 1, the isolation amplifier unit 2 and the filtering and shaping unit 3, respectively, for providing primary and secondary power supplies.

[0031] It should be noted that the isolated DC bus high-voltage detection circuit of this charging pile consists of a differential amplifier unit 1, an isolation amplifier unit 2, a filtering and shaping unit 3, a voltage-stabilized power supply unit 5 and a main control unit 4. The 500V DC bus high-voltage signal output by the charging module of the charging pile is shaped and amplified by the differential amplifier unit 1, and then sent to the isolation amplifier unit 2 to perform 1:1 proportional isolation and precise transmission of the primary voltage signal and proportional amplification and restoration. Finally, it is filtered and shaped by the filtering and shaping unit 3, and the DC bus high-voltage analog signal is sent to the main control unit 4 for data processing. The voltage-stabilized power supply unit 5 provides a regulated power supply for the primary and secondary parts of the entire detection circuit respectively.

[0032] According to this embodiment, through the differential amplifier unit 1, the isolation amplifier unit 2, the filtering and shaping unit 3 and the voltage-stabilized power supply unit 5, accurate, safe and stable detection of the 500V DC bus high-voltage signal output by the charging pile is achieved, the accuracy of signal processing and the reliability of the circuit are improved, and strong support is provided for the real-time monitoring and management of the charging pile.

[0033] like Figure 2As shown, as a preferred embodiment, the differential amplifier unit 1 in this embodiment includes resistors R1, R2, R3, R4, R5, R6, R7, capacitors C1, C2, C3 and an operational amplifier U1A, wherein the positive electrode of the charging module output end of the charging pile is electrically connected to the resistor R1 and one end of the resistor R4, respectively, the negative electrode of the charging module output end of the charging pile is electrically connected to the other end of the resistor R1 and one end of the resistor R2, respectively, the other end of the resistor R4 is electrically connected to the resistor R5, and the other end of the resistor R5 is electrically connected to the resistor R6, the capacitor C1 and the operational amplifier, respectively. The non-inverting input terminal of U1A is electrically connected, the other end of resistor R6 and capacitor C1 are commonly connected to the primary reference power supply, the other end of resistor R2 is electrically connected to resistor R3, the other end of resistor R3 is electrically connected to the inverting input terminal of operational amplifier U1A, resistor R7 and one end of capacitor C2 respectively, the other ends of capacitor C2 and resistor R7 are electrically connected to the output terminal of operational amplifier U1A, the power supply terminal of operational amplifier U1A is electrically connected to capacitor C3 and the primary power supply terminal respectively, and the other end of capacitor C3 and the ground terminal of operational amplifier U1A are connected to the primary working ground.

[0034] It should be noted that the chip model of the operational amplifier U1A is OPA2234EA, which is a low-power precision operational amplifier; its features include: low quiescent current: 250μA / amp; low offset: 100μV / MAX; low input bias current: 25nA / MAX; high CMRR, PSRR and AOL; wide power supply voltage range: +2.7V to +36V; temperature range: -40℃ to +85℃; the operational ratio of the operational amplifier U1A is 1:0.0051, which converts the 500V DC bus high-voltage signal into a 2.55V primary DC voltage signal; among them, after the differential amplifier unit shapes and reduces the voltage and the 1:0.0051 ratio high-precision differential comparison amplification, the 500V DC bus high-voltage signal output by the charging pile charging module is converted into a 2.55V primary DC voltage signal, which not only ensures the accuracy of the signal, but also improves the safety and stability of the circuit, and provides a reliable input for subsequent isolation amplification, filtering and shaping, and data processing.

[0035] like Figure 3As shown, as a preferred embodiment, the isolation amplification unit 2 in this embodiment includes resistors R8, R9, R10, R11, R12, R13, capacitors C4, C5, C6, C7, C8, an operational amplifier U1B, U3A and a photoelectric coupler U2, wherein one end of the resistor R8 is electrically connected to the output end of the operational amplifier U1A, the other end of the resistor R8 is electrically connected to the resistor R9 and the capacitor C4 respectively, the other end of the resistor R9 is electrically connected to the capacitor C5, the capacitor C6, the inverting input end of the operational amplifier U1B and the negative electrode of the first output photodiode of the photoelectric coupler U2 respectively, the positive electrode of the first output photodiode, the other end of the capacitor C4 and the capacitor C5, and the non-inverting input end of the operational amplifier U1B are connected to the primary working ground, and the other end of the capacitor C6 is electrically connected to the output end of the operational amplifier U1B and the resistor R11 respectively. The other end of the resistor R11 is electrically connected to the cathode of the input photodiode of the optocoupler U2, the anode of the input photodiode of the optocoupler U2 is electrically connected to the resistor R10, the other end of the resistor R10 is connected to the primary power supply, the cathode of the second output photodiode of the optocoupler U2 is electrically connected to the inverting input terminal of the operational amplifier U3A, the resistor R12 and the capacitor C7 respectively, the other end of the resistor R12 is electrically connected to the resistor R13, the anode of the second output photodiode of the optocoupler U2 is electrically connected to the non-inverting input terminal and the ground terminal of the operational amplifier U3A respectively, the other end of the capacitor C7 and the resistor R13 are electrically connected to the output terminal of the operational amplifier U3A, the power supply terminal of the operational amplifier U3A is electrically connected to the capacitor C8 and the secondary power supply terminal respectively, and the other end of the capacitor C8 is connected to the secondary working ground.

[0036] It should be noted that the chip model of the optocoupler U2 is HCNR201, which is a high-linearity analog optocoupler containing a high-performance AlGaAs LED and two highly matched photodiodes. The input photodiode can be used to monitor and stabilize the LED's luminous output, thereby almost eliminating the nonlinearity and drift characteristics of the LED. The output photodiode generates a photocurrent that linearly corresponds to the LED's light output. The close matching between the photodiodes and the advanced packaging design ensure the optocoupler's high linearity and stable gain. The HCNR201 can be used to provide analog signal isolation for a wide range of applications requiring good stability, linearity, bandwidth, and low cost. The HCNR201 is highly flexible and can achieve many different operating modes through appropriate design of the application circuit, including unipolar / bipolar, AC / DC, and inverting and non-inverting.

[0037] In this embodiment, the 2.55V primary DC voltage signal output by the differential amplifier unit is accurately transmitted in a 1:1 ratio isolation and proportionally amplified to restore it to a 2.55V secondary DC voltage signal, so that the input and output voltage signals remain completely consistent, with high linearity and stable gain characteristics; capacitor C6 and operational amplifier U1B form an integration circuit, and together with the optocoupler HCNR201 form an input and output feedback regulation circuit, so that the input and output linearity are closely matched, and the output voltage signal has higher accuracy.

[0038] like Figure 4 As shown, as a preferred implementation, the filtering and shaping unit 3 in this embodiment includes resistors R14, R15, capacitor C9 and operational amplifier U3B, wherein the resistor R14 is electrically connected to the output end of the operational amplifier U3A, the other end of the resistor R14 is electrically connected to the capacitor C9 and the non-inverting input end of the operational amplifier U3B, respectively, the other end of the capacitor C9 is connected to the secondary working ground, the inverting input end of the operational amplifier U3B is electrically connected to the output end of the operational amplifier U3B and the resistor R15, and the other end of the resistor R15 is electrically connected to the main control unit 4.

[0039] It should be noted that the 2.55V secondary voltage signal output by the isolation amplifier unit 2 is subjected to RC filtering, which effectively removes high-frequency noise and interference in the signal and improves the purity of the signal. It is then shaped by the follower circuit composed of the operational amplifier U3B, which not only enhances the stability and anti-interference ability of the signal, but also ensures that the amplitude and phase characteristics of the signal meet the requirements of subsequent processing. Finally, the DC bus high-voltage analog signal is sent to the main control unit 4 for data processing.

[0040] like Figure 5 As shown in FIG1 , as a preferred embodiment, the voltage-stabilized power supply unit 5 in this embodiment includes capacitors C10, C11, C12, C13, C14, C15, an isolated power supply U4 and a voltage-stabilized reference source U5, wherein the positive electrode of the input end of the isolated power supply U4 is electrically connected to the capacitor C11, the capacitor C10 and the external power supply, respectively, the other ends of the capacitors C10 and C11 are respectively connected to the negative electrode of the input end of the isolated power supply U4 and the secondary working ground, and the positive electrode of the output end of the isolated power supply U4 is respectively connected to the resistor R16, the resistor R17 and the resistor R18. Capacitor C12, capacitor C13, capacitor C14, the input end of the voltage-stabilized reference source U5 and the first voltage output end of the voltage-stabilized power supply unit 5 are electrically connected, the negative electrode of the output end of the isolation power supply U4 is respectively connected to the other end of the resistor R16, the other end of the capacitor C12, the other end of the capacitor C13, the other end of the capacitor C14, capacitor C15 and the ground end of the voltage-stabilized reference source U5 to the primary working ground, and the output end of the voltage-stabilized reference source U5 is respectively electrically connected to the second voltage output end of the voltage-stabilized power supply unit 5 and the other end of the capacitor C15.

[0041] It should be noted that the isolated power supply adopts the 5V to 5V conversion DC isolated power supply module F0505S-1WR3; the voltage regulated reference source adopts the ADR441 chip, which is an ultra-low noise, low power consumption, high-precision LDOXFET reference source. The voltage regulated power supply unit 5 provides 5V DC regulated power supply and 2.5V reference power supply to the power supply ends of the differential amplifier unit 1, the isolation amplifier unit 2 and the filter shaping unit 3 to ensure the stability of the detection signal.

[0042] Specifically, the input voltage of the voltage-stabilized power supply unit 5 in this embodiment is +5V, the first voltage output voltage of the voltage-stabilized power supply unit 5 is a +5V DC voltage-stabilized power supply, the second voltage output voltage of the voltage-stabilized power supply unit 5 is a +2.5V reference power supply, the first voltage output of the voltage-stabilized power supply unit 5 is electrically connected to the power supply end of the differential amplifier unit 1 and the power supply end of the primary power supply of the isolation amplifier unit 2, the second voltage output of the voltage-stabilized power supply unit 5 is electrically connected to the reference power supply end of the differential amplifier unit 1, and the input of the voltage-stabilized power supply unit 5 is electrically connected to the secondary power supply of the isolation amplifier unit 2 and the power supply end of the filtering and shaping unit 3.

[0043] Working principle: After being shaped and stepped down by the differential amplifier unit 1 and amplified by the high-precision differential comparison with a ratio of 1:0.0051, the 500V DC bus high-voltage signal output by the charging pile charging module is converted into a 2.55V primary DC voltage signal. The 2.55V primary DC voltage signal output by the differential amplifier unit 1 is then isolated and accurately transmitted in a 1:1 ratio and amplified proportionally to be restored to a 2.55V secondary DC voltage signal through the isolation amplifier unit 2. Finally, the 2.55V secondary voltage signal output by the isolation amplifier unit 2 is RC filtered by the filtering and shaping unit 3, and then shaped by the follower circuit composed of the operational amplifier U3B, and the DC bus high-voltage analog signal is sent to the main control unit 4 for data processing.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A charging pile isolated DC bus high voltage detection circuit, characterized in that: It comprises a differential amplification unit (1), an isolation amplification unit (2), a filtering and shaping unit (3) and a main control unit (4), wherein: The input end of the differential amplifier unit (1) is electrically connected to the output end of the charging module of the charging pile, and is used to convert the DC bus high voltage signal into a primary DC voltage signal; The input end of the isolation amplifier unit (2) is electrically connected to the output end of the differential amplifier unit (1), and is used to isolate and transmit the primary DC voltage signal and amplify it proportionally to restore it into a secondary DC voltage signal; The input end of the filtering and shaping unit (3) is electrically connected to the output end of the isolation amplifier unit (2), and the output end of the filtering and shaping unit (3) is electrically connected to the input end of the main control unit (4), for filtering and shaping the secondary DC voltage signal and sending it to the main control unit (4) for data processing.

2. The charging pile isolated DC bus high voltage detection circuit according to claim 1, characterized in that: The differential amplifier unit (1) includes resistors R1, R2, R3, R4, R5, R6, R7, capacitors C1, C2, C3 and an operational amplifier U1A, wherein the positive electrode of the charging module output end of the charging pile is electrically connected to the resistor R1 and one end of the resistor R4 respectively, the negative electrode of the charging module output end of the charging pile is electrically connected to the other end of the resistor R1 and one end of the resistor R2 respectively, the other end of the resistor R4 is electrically connected to the resistor R5, and the other end of the resistor R5 is electrically connected to the resistor R6, the capacitor C1 and the positive input of the operational amplifier U1A respectively. The two ends are electrically connected, the other end of resistor R6 and capacitor C1 are commonly connected to the primary reference power supply, the other end of resistor R2 is electrically connected to resistor R3, the other end of resistor R3 is respectively electrically connected to the inverting input terminal of operational amplifier U1A, resistor R7 and one end of capacitor C2, the other ends of capacitor C2 and resistor R7 are electrically connected to the output terminal of operational amplifier U1A, the power supply terminal of operational amplifier U1A is respectively electrically connected to capacitor C3 and the primary power supply terminal, and the other end of capacitor C3 and the ground terminal of operational amplifier U1A are connected to the primary working ground.

3. The charging pile isolated DC bus high voltage detection circuit according to claim 2, characterized in that: The isolation amplifier unit (2) includes resistors R8, R9, R10, R11, R12, R13, capacitors C4, C5, C6, C7, C8, an operational amplifier U1B, U3A and a photoelectric coupler U2, wherein one end of the resistor R8 is electrically connected to the output end of the operational amplifier U1A, the other end of the resistor R8 is electrically connected to the resistor R9 and the capacitor C4 respectively, the other end of the resistor R9 is electrically connected to the capacitor C5, the capacitor C6, the inverting input end of the operational amplifier U1B and the negative electrode of the first output photodiode of the photoelectric coupler U2 respectively, the positive electrode of the first output photodiode, the other end of the capacitor C4 and the capacitor C5, and the positive input end of the operational amplifier U1B are connected to the primary working ground, the other end of the capacitor C6 is electrically connected to the output end of the operational amplifier U1B and the resistor R11 respectively, and the resistor R1 is electrically connected to the output end of the operational amplifier U1B. The other end of 1 is electrically connected to the cathode of the input photodiode of the optocoupler U2, the anode of the input photodiode of the optocoupler U2 is electrically connected to the resistor R10, the other end of the resistor R10 is connected to the primary power supply, the cathode of the second output photodiode of the optocoupler U2 is electrically connected to the inverting input terminal of the operational amplifier U3A, the resistor R12 and the capacitor C7 respectively, the other end of the resistor R12 is electrically connected to the resistor R13, the anode of the second output photodiode of the optocoupler U2 is electrically connected to the non-inverting input terminal and the ground terminal of the operational amplifier U3A respectively, the other ends of the capacitor C7 and the resistor R13 are electrically connected to the output terminal of the operational amplifier U3A, the power supply terminal of the operational amplifier U3A is electrically connected to the capacitor C8 and the secondary power supply terminal respectively, and the other end of the capacitor C8 is connected to the secondary working ground.

4. The charging pile isolated DC bus high voltage detection circuit according to claim 3, characterized in that: The filtering and shaping unit (3) includes resistors R14, R15, a capacitor C9 and an operational amplifier U3B, wherein the resistor R14 is electrically connected to the output end of the operational amplifier U3A, the other end of the resistor R14 is electrically connected to the capacitor C9 and the positive phase input end of the operational amplifier U3B respectively, the other end of the capacitor C9 is connected to the secondary working ground, the inverting input end of the operational amplifier U3B is electrically connected to the output end of the operational amplifier U3B and the resistor R15, and the other end of the resistor R15 is electrically connected to the main control unit (4).

5. The charging pile isolated DC bus high voltage detection circuit according to claim 1, characterized in that: The invention also includes a voltage-stabilized power supply unit (5), the input end of which is electrically connected to an external power supply, and the output and input ends of which are electrically connected to the power supply ends of the differential amplifier unit (1), the isolation amplifier unit (2), and the filter shaping unit (3), respectively, for providing primary and secondary power supplies.

6. The charging pile isolated DC bus high voltage detection circuit according to claim 5, characterized in that: The voltage-stabilized power supply unit (5) comprises capacitors C10, C11, C12, C13, C14, C15, an isolated power supply U4 and a voltage-stabilized reference source U5, wherein the positive electrode of the input end of the isolated power supply U4 is electrically connected to the capacitor C11, the capacitor C10 and the external power supply respectively, the other ends of the capacitors C10 and C11 are respectively connected to the negative electrode of the input end of the isolated power supply U4 and the secondary working ground, and the positive electrode of the output end of the isolated power supply U4 is respectively connected to the resistor R16, the capacitor C12, the capacitor C13, The capacitor C14, the input end of the voltage-stabilized reference source U5 and the first voltage output end of the voltage-stabilized power supply unit (5) are electrically connected; the negative electrode of the output end of the isolation power supply U4 is respectively connected to the other end of the resistor R16, the other end of the capacitor C12, the other end of the capacitor C13, the other end of the capacitor C14, the capacitor C15 and the ground end of the voltage-stabilized reference source U5 to the primary working ground; the output end of the voltage-stabilized reference source U5 is respectively electrically connected to the second voltage output end of the voltage-stabilized power supply unit (5) and the other end of the capacitor C15.

7. The charging pile isolated DC bus high voltage detection circuit according to claim 6, characterized in that: The input terminal voltage of the voltage-stabilized power supply unit (5) is +5V, the first voltage output terminal voltage of the voltage-stabilized power supply unit (5) is a +5V DC voltage-stabilized power supply, the second voltage output terminal voltage of the voltage-stabilized power supply unit (5) is a +2.5V reference power supply, the first voltage output terminal of the voltage-stabilized power supply unit (5) is electrically connected to the power supply terminal of the differential amplifier unit (1) and the primary power supply terminal of the isolation amplifier unit (2), the second voltage output terminal of the voltage-stabilized power supply unit (5) is electrically connected to the reference power supply terminal of the differential amplifier unit (1), and the input terminal of the voltage-stabilized power supply unit (5) is electrically connected to the secondary power supply of the isolation amplifier unit (2) and the power supply terminal of the filtering and shaping unit (3).

8. The charging pile isolated DC bus high voltage detection circuit according to claim 2, characterized in that: The chip model of the operational amplifier U1A is OPA2234EA.

9. The charging pile isolated DC bus high voltage detection circuit according to claim 8, characterized in that: The operational amplifier U1A has an operational ratio of 1:0.0051, converting the 500V DC bus high voltage signal into a 2.55V primary DC voltage signal.

10. The charging pile isolated DC bus high voltage detection circuit according to claim 3, characterized in that: The chip model of the photoelectric coupler U2 is HCNR201.

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