Charging pile PE grounding detection circuit based on half-wave rectification-optocoupler dynamic coupling
The charging pile PE grounding detection circuit with half-wave rectification and optocoupler dynamic coupling solves the problems of insufficient reliability, weak anti-interference ability and high cost of traditional detection technology, and realizes grounding fault detection with high reliability, low cost and fast response, which is suitable for complex environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN TINFULL TECH CO LTD
- Filing Date
- 2025-05-26
- Publication Date
- 2026-04-28
AI Technical Summary
Traditional charging pile PE grounding detection technology suffers from insufficient reliability, weak anti-interference ability, and excessive cost.
A charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling is adopted, including a signal conversion module and an isolation coupling module. By utilizing the current-limiting half-wave rectification path, power frequency filtering and energy storage unit and optical coupling module, signal conversion and physical isolation between the high-voltage side and the low-voltage side are achieved.
It improves the reliability and anti-interference ability of detection, reduces costs, meets international standard requirements, has rapid response and fault diagnosis capabilities, and can adapt to complex environments.
Smart Images
Figure CN224176718U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of charging pile technology for two-wheeled electric bicycles, and in particular to a charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling. Background Technology
[0002] With the increasing popularity of electric bicycles, the safety of charging stations has become a core concern in the industry. International standards (such as IEC 61851 and GB / T 18487) clearly require that charging equipment must reliably detect the connection status of the protective earth (PE) to avoid risks such as leakage and electric shock. Traditional PE grounding detection technologies have the following shortcomings:
[0003] 1. Insufficient reliability of detection:
[0004] Early solutions relied heavily on voltage comparators to directly monitor the potential difference between the PE and the live / neutral wires. However, harmonic interference from the AC power grid and fluctuations in grounding impedance can easily lead to misjudgments (±10% threshold drift), and stability decreases significantly in complex environments such as humidity and corrosion.13
[0005] 2. Weak isolation and anti-interference capabilities:
[0006] Some designs employ non-isolated detection circuits, with the high-voltage side directly coupled to the low-voltage control unit, posing a risk of common-mode surge damage to the MCU (typical failure voltage <1kV). A few solutions introduce optocoupler isolation, but rely on discrete filter networks (such as multi-stage LC filters), resulting in high circuit complexity and response delay (>50ms). Utility Model Content
[0007] The main purpose of this invention is to propose a charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling, which aims to solve the problems of insufficient reliability, weak anti-interference ability and high cost in the existing charging pile PE grounding detection technology. It achieves high reliability, low cost and fast response grounding fault detection through a simplified analog front-end architecture.
[0008] To achieve the above objectives, this utility model proposes a charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling, comprising: a signal conversion module and an isolation coupling module, wherein the signal conversion module includes a current-limiting half-wave rectification path and a power frequency filtering and energy storage unit, the current-limiting half-wave rectification path includes a resistor R1 and a diode D1, the power frequency filtering and energy storage unit includes an electrolytic capacitor C1, and the isolation coupling module includes an optocoupler U1;
[0009] One end of the resistor R1 is connected to the live wire or neutral wire of the power supply, and the other end is connected to the anode of the diode D1, forming the current-limiting half-wave rectifier path;
[0010] The positive terminal of the electrolytic capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the electrolytic capacitor C1 is connected to the PE ground terminal, thus forming the power frequency filtering and energy storage unit.
[0011] The anode of the input terminal of the optocoupler U1 is connected to the cathode of the diode D1, the cathode of the input terminal of the optocoupler U1 is connected to the PE ground terminal, the collector of the output terminal of the optocoupler U1 is connected to the 3.3V power supply of the MCU through the pull-up resistor R2, and the emitter of the output terminal of the optocoupler U1 is connected to the digital ground.
[0012] A further technical solution of this utility model is that the electrolytic capacitor C1 is a wide-temperature electrolytic capacitor, with a range of -40℃ to +105℃.
[0013] A further technical solution of this utility model is that the resistor R1 is a low-temperature drift metal film resistor with a temperature of ±100ppm / ℃.
[0014] A further technical solution of this utility model is that the PE terminal is gold-plated, and the contact resistance is ≤0.1Ω.
[0015] A further technical solution of this utility model is that the input and output ends of the optocoupler U1 are coated with conformal coating.
[0016] The charging pile PE grounding detection circuit proposed in this utility model, based on half-wave rectification-optical coupler dynamic coupling, achieves the following significant advantages in terms of safety, reliability, and economy through its innovative architecture of half-wave rectification-optical coupler dynamic coupling:
[0017] I. Improved Detection Reliability
[0018] 1. Optimization against power frequency interference
[0019] The combination of half-wave rectification (IN4007) and RC filtering (200kΩ + 220μF) converts AC signals into stable DC levels (fluctuation < ±3%), effectively suppressing power frequency harmonics and high-frequency noise (attenuation ratio > 40dB@1MHz). Compared with the traditional direct comparison method (±15% threshold drift), the false positive rate is reduced from 5% to below 0.03%.
[0020] 2. Enhanced detection capability for disconnected connections
[0021] Based on the charge discharge characteristics of electrolytic capacitors (C1), it can accurately identify loose connection faults with PE contact resistance >1Ω, avoiding the problem of missed detection caused by impedance fluctuations in traditional voltage comparison schemes.
[0022] II. Security Isolation and Dynamic Response
[0023] 1. Electrical isolation performance
[0024] The optocoupler (PC817) achieves physical isolation between the high-voltage side (AC 220V) and the low-voltage MCU, and can withstand a 2.5kV surge voltage (IEC 61000-4-5 standard), avoiding the risk of MCU burnout caused by non-isolation solutions.
[0025] 2. Fault response speed
[0026] The optocoupler output is combined with a 10kΩ pull-up resistor and interrupt trigger logic. When the PE is disconnected, the response delay is ≤20ms, which far exceeds the 100ms threshold required by the national standard GB / T18487.1.
[0027] III. Cost and Compatibility Optimization
[0028] 1. Reduced hardware costs
[0029] The number of components has been reduced from 32 in the traditional solution to 11 (including R1, D1, C1, U1, etc.), reducing BOM costs by 67% and making it suitable for large-scale deployment of charging piles from 7kW to 22kW.
[0030] 2. Enhanced environmental adaptability
[0031] Wide temperature design (-40℃~+85℃) electrolytic capacitors and low temperature drift resistors to offset the effect of temperature on the threshold.
[0032] The output terminals of the optocoupler are coated with conformal coating to ensure an insulation resistance of >100MΩ in high humidity environments (RH 95%).
[0033] IV. Standardization and Intelligentization Expansion
[0034] 1. Meets international safety certification standards
[0035] It meets the requirements of IEC 61851 (insulation resistance > 1MΩ) and GB / T18487 (grounding resistance ≤ 4Ω) and supports rapid CCC certification.
[0036] 2. Fault diagnosis expansion capability
[0037] By monitoring the output pulse width of the optocoupler, the MCU can report hidden faults such as capacitor aging or contact terminal corrosion in real time, thereby improving the equipment's full life cycle management capabilities.
[0038] This invention addresses the shortcomings of traditional detection technologies, such as insufficient reliability, high cost, and slow response, providing a cost-effective and robust solution for the safety protection of charging piles, and has significant industrial application value. Attached Figure Description
[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0040] Figure 1 This is a schematic diagram of the circuit structure of a preferred embodiment of the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling of this utility model.
[0041] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0042] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0043] To address the issues of insufficient reliability, weak anti-interference capability, and high cost in existing charging pile PE grounding detection technologies, a charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling is proposed.
[0044] Please refer to Figure 1 The preferred embodiment of the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling of this utility model includes: a signal conversion module and an isolation coupling module. The signal conversion module includes a current-limiting half-wave rectification path and a power frequency filtering and energy storage unit. The current-limiting half-wave rectification path includes a resistor R1 and a diode D1. The power frequency filtering and energy storage unit includes an electrolytic capacitor C1. The isolation coupling module includes an optocoupler U1.
[0045] One end of the resistor R1 is connected to the power supply live wire or neutral wire, and the other end is connected to the anode of the diode D1, forming the current-limiting half-wave rectifier path.
[0046] The positive terminal of the electrolytic capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the electrolytic capacitor C1 is connected to the PE ground terminal, thus forming the power frequency filtering and energy storage unit.
[0047] The anode of the input terminal of the optocoupler U1 is connected to the cathode of the diode D1, the cathode of the input terminal of the optocoupler U1 is connected to the PE ground terminal, the collector of the output terminal of the optocoupler U1 is connected to the 3.3V power supply of the MCU through the pull-up resistor R2, and the emitter of the output terminal of the optocoupler U1 is connected to the digital ground.
[0048] The overall circuit architecture of the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling in this embodiment includes the signal conversion module and the isolation coupling module.
[0049] The input side of the signal conversion module is as follows: the AC mains live wire (L) or neutral wire (N) is current-limited by the resistor R1 (200kΩ / 2W), and then half-wave rectified by the diode D1 (IN4007) to generate a pulsating DC signal.
[0050] The power frequency filtering and energy storage unit of the signal conversion module: The electrolytic capacitor C1 (220μF / 50V) is connected in parallel between the cathode of the diode D1 and the PE ground terminal. Its charging and discharging characteristics are used to convert the pulsating signal into a stable DC level, while filtering out power frequency harmonics and high-frequency noise.
[0051] The isolation coupling module adopts an optocoupler drive design: the cathode of the diode D1 and the positive terminal of the electrolytic capacitor C1 are connected to the anode (pin 1) of the light-emitting diode of the optocoupler U1 (PC817), and the cathode (pin 2) of the light-emitting diode of the optocoupler U1 (PC817) is directly connected to the PE ground terminal, forming an optocoupler input circuit.
[0052] The output logic interface of the isolation coupling module is as follows: the collector (pin 4) of the optocoupler U1 is pulled up to the MCU power supply voltage (3.3V) through resistor R2 (10kΩ), the emitter (pin 3) is connected to digital ground (GND), and the output terminal is directly connected to the MCU interrupt pin.
[0053] The workflow of the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling in this embodiment is as follows:
[0054] Step 1: Signal Acquisition and Rectification / Filtering
[0055] When the live wire or neutral wire is normally connected to PE (low impedance path), the AC current is limited by the resistor R1 and then rectified by the diode D1 in the forward half-wave direction.
[0056] The electrolytic capacitor C1 charges to its peak voltage during the positive half-cycle and eventually maintains an approximately DC level (about 1.5V).
[0057] Step 2: Dynamic coupling of optical couplers:
[0058] Under normal conditions: When PE is reliably grounded, the voltage across the electrolytic capacitor C1 is continuously higher than the LED conduction threshold of the optocoupler U1 (typical value V_F = 1.2V for PC817), the input terminal of the optocoupler U1 is turned on, the output terminal (pin 4) is pulled down to GND, and the MCU detects a low level.
[0059] Specifically, during the AC half-cycle: the diode D1 is turned on, and the current charges the electrolytic capacitor C1 through the resistor R1 to the peak voltage (approximately 310V); during the negative half-cycle, the diode D1 is turned off, and the electrolytic capacitor C1 slowly discharges through the resistor R1, maintaining a DC level ≥1.2V.
[0060] The input terminal of the optocoupler U1 is continuously on, and the output terminal (PE-DET-EINT-PC6) remains at a low level (0.2V), which the MCU determines to be a normal grounding.
[0061] In a fault state: when PE is disconnected, the charging circuit of the electrolytic capacitor C1 is interrupted, and the stored charge is quickly discharged through the LED of the optocoupler U1 (the diode D1 blocks in reverse). The input terminal of the optocoupler U1 is cut off, and the output terminal is pulled up to 3.3V by the resistor R2, triggering the MCU interrupt signal.
[0062] Specifically, when the PE is disconnected or has a loose connection, the charging circuit of the electrolytic capacitor C1 is interrupted, and the stored charge is quickly discharged to the PE terminal through the LED of the optocoupler U1 (the discharge time is determined by the capacity of the electrolytic capacitor C1 and the LED conduction current).
[0063] When the input current of the optocoupler U1 is below the threshold, it is cut off, and the output is pulled high to 3.3V by resistor R2, triggering an MCU interrupt.
[0064] It should be noted that the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling in this embodiment has the function of fault diagnosis extension.
[0065] 1. Detection of hidden faults:
[0066] The MCU periodically monitors the output pulse width of the optocoupler: Under normal conditions, the pulse width is synchronized with the power frequency period (20ms). If an abnormally shortened pulse width (<10ms) is detected, it is determined that the electrolytic capacitor C1 is aging or the circuit is corroded.
[0067] When the cumulative number of software failures exceeds a threshold (e.g., 5 times / hour), the system will automatically report the issue to the maintenance system.
[0068] 2. Safety redundancy protection:
[0069] The distance between the high-voltage side and the low-voltage side is ≥6mm (IEC 60950 standard). The input terminal of the optocoupler U1 is connected in parallel with a TVS diode (SMBJ30CA) to resist 2.5kV surge impact.
[0070] Furthermore, in this embodiment, the electrolytic capacitor C1 is a wide-temperature electrolytic capacitor, ranging from -40℃ to +105℃. The resistor R1 is a low-temperature drift metal film resistor with a temperature range of ±100ppm / ℃.
[0071] This embodiment uses a wide-temperature electrolytic capacitor (-40℃). ～ +105℃) and low-temperature drift metal film resistors (±100ppm / ℃) to offset threshold drift caused by temperature changes and improve environmental adaptability.
[0072] Furthermore, in this embodiment, the PE terminal is gold-plated, with a contact resistance ≤0.1Ω. The input and output terminals of the optocoupler U1 are coated with conformal coating.
[0073] In this embodiment, the PE connection terminal is gold-plated, with a contact resistance ≤0.1Ω; the optocoupler input / output terminals are coated with conformal coating to ensure an insulation resistance >100MΩ in a RH 95% environment. This achieves corrosion resistance and moisture protection.
[0074] In addition, it should be noted that this embodiment has a fault redundancy mechanism. If the electrolytic capacitor C1 loses capacity due to aging, and the conduction time of the optocoupler U1 is shortened, the MCU can actively report the component failure by monitoring the interrupt signal pulse width (normally >40ms) to avoid missed detection.
[0075] The following describes the technical effectiveness verification of the charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling of this utility model.
[0076] By building a 2kW AC charging pile prototype for testing, this utility model achieves the following performance indicators:
[0077] 1. False positive rate: 0.03% (5% for traditional methods);
[0078] 2. PE loose connection detection lower limit: 100% alarm triggered when contact resistance ≥ 1Ω;
[0079] 3. Environmental adaptability: Insulation resistance >100MΩ under high temperature (85℃) and RH (95%) conditions.
[0080] This invention optimizes component parameters and dynamic coupling mechanisms, simplifying hardware design while meeting the stringent requirements of national standard GB / T 18487.1 and IEC 61851-1.
[0081] This utility model achieves the following core objectives:
[0082] 1. Improve the reliability of grounding status criteria.
[0083] By combining a single diode (IN4007) half-wave rectifier with RC filtering (200kΩ metal film resistor + 220μF electrolytic capacitor), the AC grid signal is converted to DC level, eliminating the interference of power frequency harmonics and transient noise on the detection logic, and reducing the fluctuation range of the PE grounding status determination threshold from ±15% in the traditional scheme to within ±3%.
[0084] 2. Enhance electrical isolation and anti-interference capabilities
[0085] The optocoupler (PC817) is used to achieve physical isolation between the high-voltage side (AC 220V) and the low-voltage control unit (MCU 3.3V). This not only blocks common-mode surges (withstanding 2.5kV) but also ensures the complete transmission of ground fault signals, avoiding the risk of MCU false triggering or damage caused by traditional non-isolation solutions.
[0086] 3. Adaptable to complex working conditions and environments
[0087] By optimizing the charge discharge path of the electrolytic capacitor (diode reverse blocking + optocoupler LED fast conduction), it is ensured that the interrupt signal can still be stably triggered under harsh conditions such as high temperature (-40℃~+85℃), high humidity (RH 95%) and PE wire corrosion (contact resistance ≤1Ω), with a fault detection rate ≤0.1%.
[0088] This invention is particularly suitable for grounding safety monitoring of AC charging piles. By deeply integrating the simplification of the analog front end with digital interruption logic, it provides an innovative solution for low-cost and high-reliability charging pile safety protection while ensuring compliance with international / national standards such as IEC 61851 and GB / T 18487.
[0089] The charging pile PE grounding detection circuit proposed in this utility model, based on half-wave rectification-optical coupler dynamic coupling, achieves the following significant advantages in terms of safety, reliability, and economy through its innovative architecture of half-wave rectification-optical coupler dynamic coupling:
[0090] I. Improved Detection Reliability
[0091] 1. Optimization against power frequency interference
[0092] The combination of half-wave rectification (IN4007) and RC filtering (200kΩ + 220μF) converts AC signals into stable DC levels (fluctuation < ±3%), effectively suppressing power frequency harmonics and high-frequency noise (attenuation ratio > 40dB@1MHz). Compared with the traditional direct comparison method (±15% threshold drift), the false positive rate is reduced from 5% to below 0.03%.
[0093] 2. Enhanced detection capability for disconnected connections
[0094] Based on the charge discharge characteristics of electrolytic capacitors (C1), it can accurately identify loose connection faults with PE contact resistance >1Ω, avoiding the problem of missed detection caused by impedance fluctuations in traditional voltage comparison schemes.
[0095] II. Security Isolation and Dynamic Response
[0096] 1. Electrical isolation performance
[0097] The optocoupler (PC817) achieves physical isolation between the high-voltage side (AC 220V) and the low-voltage MCU, and can withstand a 2.5kV surge voltage (IEC 61000-4-5 standard), avoiding the risk of MCU burnout caused by non-isolation solutions.
[0098] 2. Fault response speed
[0099] The optocoupler output is combined with a 10kΩ pull-up resistor and interrupt trigger logic. When the PE is disconnected, the response delay is ≤20ms, which far exceeds the 100ms threshold required by the national standard GB / T 18487.1.
[0100] III. Cost and Compatibility Optimization
[0101] 1. Reduced hardware costs
[0102] The number of components has been reduced from 32 in the traditional solution to 11 (including R1, D1, C1, U1, etc.), reducing BOM costs by 67% and making it suitable for large-scale deployment of charging piles from 7kW to 22kW.
[0103] 2. Enhanced environmental adaptability
[0104] Wide temperature design (-40℃~+85℃) electrolytic capacitors and low temperature drift resistors to offset the effect of temperature on the threshold.
[0105] The output terminals of the optocoupler are coated with conformal coating to ensure an insulation resistance of >100MΩ in high humidity environments (RH 95%).
[0106] IV. Standardization and Intelligentization Expansion
[0107] 1. Meets international safety certification standards
[0108] It meets the requirements of IEC 61851 (insulation resistance > 1MΩ) and GB / T18487 (grounding resistance ≤ 4Ω) and supports rapid CCC certification.
[0109] 2. Fault diagnosis expansion capability
[0110] By monitoring the output pulse width of the optocoupler, the MCU can report hidden faults such as capacitor aging or contact terminal corrosion in real time, thereby improving the equipment's full life cycle management capabilities.
[0111] This invention addresses the shortcomings of traditional detection technologies, such as insufficient reliability, high cost, and slow response, providing a cost-effective and robust solution for the safety protection of charging piles, and has significant industrial application value.
[0112] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the concept of the present utility model and using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present utility model.
Claims
1. A charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling, characterized in that, include: The signal conversion module includes a current-limiting half-wave rectifier path and a power frequency filter and energy storage unit. The current-limiting half-wave rectifier path includes a resistor R1 and a diode D1. The power frequency filter and energy storage unit includes an electrolytic capacitor C1. The isolation coupling module includes an optocoupler U1. One end of the resistor R1 is connected to the live wire or neutral wire of the power supply, and the other end is connected to the anode of the diode D1, forming the current-limiting half-wave rectifier path; The positive terminal of the electrolytic capacitor C1 is connected to the cathode of the diode D1, and the negative terminal of the electrolytic capacitor C1 is connected to the PE ground terminal, thus forming the power frequency filtering and energy storage unit. The anode of the input terminal of the optocoupler U1 is connected to the cathode of the diode D1, the cathode of the input terminal of the optocoupler U1 is connected to the PE ground terminal, the collector of the output terminal of the optocoupler U1 is connected to the 3.3V power supply of the MCU through the pull-up resistor R2, and the emitter of the output terminal of the optocoupler U1 is connected to the digital ground.
2. The charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling according to claim 1, characterized in that, The electrolytic capacitor C1 is a wide-temperature electrolytic capacitor, ranging from -40℃ to +105℃.
3. The charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling according to claim 1, characterized in that, The resistor R1 is a low-temperature drift metal film resistor with a temperature of ±100ppm / ℃.
4. The charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling according to claim 1, characterized in that, The PE terminal block is gold-plated, and the contact resistance is ≤0.1Ω.
5. The charging pile PE grounding detection circuit based on half-wave rectification-optical coupler dynamic coupling according to claim 1, characterized in that, The input and output terminals of the optocoupler U1 are coated with conformal coating.