A voltage-withstanding relay for insulation detection

Abstract

The utility model provides a kind of withstand voltage relay for insulation detection, comprising: primary side drive module, including a light emitting diode, its anode and cathode are connected to control signal source respectively;Photo-coupler control module, including a photosensitive switch device, its control end is connected with the light emitting diode by photo-coupler mode;Conduction module, including the first terminal and second terminal of the photosensitive switch device, respectively constitute the input end and output end of relay;Withstand voltage enhancement module, including two resistors, respectively between the first terminal and second terminal are connected, and with the conduction path of the photosensitive switch device parallelly connected.When the photosensitive switch device is turned on, low impedance path is formed between the first terminal and second terminal, current bypasses the resistor;When the photosensitive switch device is disconnected, the resistor forms fixed resistance conduction path.The relay structure is compact, control is reliable, and is applicable to insulation monitoring in high-voltage energy storage system.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a withstand voltage relay for insulation detection. Background Technology

[0002] As a critical infrastructure in the utilization of new energy sources, the safety of energy storage systems is of paramount importance. Insulation detection is a crucial means of monitoring the electrical insulation status between the DC bus and ground in energy storage systems. It can promptly detect leakage or short circuits between the positive or negative terminals and ground, thereby ensuring the safe operation of the system.

[0003] Currently, most mainstream energy storage systems use the unbalanced method for insulation resistance detection. The basic principle is to form measurement circuits between the positive and negative terminals through bridge arm switches and the grounding terminal, respectively, and then determine the insulation resistance between the positive and negative terminals and ground through voltage division detection and calculation. This approach typically requires a high-voltage relay (or solid-state relay) in each bridge arm circuit for on / off control.

[0004] However, existing relays operate with their terminals open when disconnected. When a short circuit occurs between the positive or negative terminals and the protective earth (PE), the relay arms must withstand the entire system bus voltage. Taking a DC 1500V or DC 2000V energy storage system as an example, this voltage is directly applied between the relay's disconnected terminals, severely challenging the relay's withstand voltage performance and potentially leading to device breakdown, insulation failure, or thermal failure. Therefore, relays commonly suffer from insufficient withstand voltage, poor reliability, and high cost in insulation testing applications.

[0005] To address these issues, some solutions attempt to create a voltage divider path by connecting a high-resistance resistor in parallel externally, thus reducing the voltage load across the relay when it is open. However, these structures are mostly external additions, leading to engineering problems such as complex layout, unstable connections, and increased size. Furthermore, the resistor itself is affected by factors such as temperature drift and uneven voltage distribution, resulting in limited voltage suppression effectiveness.

[0006] Therefore, there is an urgent need to provide a relay solution that is compact, highly reliable, and capable of withstanding breaking voltage, so as to effectively reduce the pressure when the bridge arm switch is disconnected without changing the detection principle, thereby improving the safety of the overall insulation detection system and the life of the devices. Utility Model Content

[0007] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a compact and highly reliable withstand voltage relay for insulation detection.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A withstand voltage relay for insulation detection includes: a primary-side drive module, an optocoupler control module, a conduction module, and a withstand voltage enhancement module. The primary-side drive module includes a light-emitting diode (LED) with its anode and cathode connected to a control signal source, respectively. The optocoupler control module includes a photosensitive switch, the control terminal of which is connected to the LED via an optocoupler. The conduction module includes a first terminal and a second terminal of the photosensitive switch, which respectively constitute the input and output terminals of the relay. The withstand voltage enhancement module includes two resistors connected between the first and second terminals, respectively, and connected in parallel with the conduction path of the photosensitive switch. When the photosensitive switch is in the conduction state, a low-impedance path is formed between the first and second terminals, allowing current to bypass the resistors. When the photosensitive switch is in the off state, the resistors form a conduction path with a fixed resistance value, used to share the relay's disconnection voltage in a high-voltage circuit.

[0009] Furthermore, the resistor has a resistance of 0.5MΩ, which is used to provide a stable voltage divider path when the switching device is disconnected, so that the voltage across the relay is limited to less than 1 / 5 of the original system voltage in the disconnected state.

[0010] Furthermore, the photosensitive switching device is a MOSFET, and a resistor is connected between its drain and source via gold wire bonding.

[0011] Furthermore, the resistor is formed on the surface of an aluminum nitride (AlN) ceramic substrate using a thick-film laser etching process, and the MOSFET chip is soldered to the resistor terminal electrode, forming a secondary side structure through eutectic bonding.

[0012] Furthermore, the resistor's temperature drift coefficient does not exceed ±25ppm / ℃, and its power rating is 0.25W, ensuring that the resistance change is less than 1% under long-term operation in a high-voltage environment.

[0013] Furthermore, the relay is packaged in an SMD-5 package, with a secondary switch port withstand voltage of not less than DC600V and an isolation withstand voltage between the primary and secondary sides of 5000Vrms / min, to meet the ground insulation requirements of different potentials in the energy storage system.

[0014] Furthermore, the resistor and the photosensitive switch form a secondary bridge arm structure and are connected in the detection path between the positive or negative terminal of the battery cluster and the PE ground. The change in voltage across the resistor is detected to reflect the change in the insulation impedance of the positive or negative terminal to ground.

[0015] Furthermore, the on-state impedance of the photosensitive switching device is no greater than 1Ω, and the off-state impedance is greater than 10MΩ, so as to achieve effective isolation and switching of the voltage path.

[0016] Furthermore, the operating current of the light-emitting diode is 5mA to 15mA, and the light intensity of its primary side is controlled to achieve adjustment of the reliability of the secondary side conduction.

[0017] Furthermore, the relay is installed in the insulation detection bridge arm circuit, and when the energy storage system encounters a PE short-circuit fault, the voltage is reduced to less than 400V at both ends of the relay by the voltage divider of the withstand voltage enhancement module according to the following formula.

[0018] The aforementioned withstand voltage relay for insulation testing employs a parallel high-resistance resistor connected when the photosensitive switch is open. This creates a stable voltage divider path within the relay, resolving the breakdown risk and thermal failure issue inherent in existing insulation testing bridge arms where the relay must withstand the full system's DC high voltage when open. Compared to traditional methods of voltage sharing via external resistors, this invention features a compact structure and high integration. The resistor is manufactured using high-voltage, low-temperature drift technology and is co-packaged with the switch chip, effectively improving voltage distribution stability and thermal reliability. This solution significantly enhances the relay's withstand voltage when open without altering the insulation testing principle of the energy storage system, improving the overall insulation testing safety and device lifespan of the system, and meeting the stringent requirements of high-voltage energy storage systems for bridge arm relays. Attached Figure Description

[0019] Figure 1 The circuit diagram of the relay provided by this utility model is shown. Figure 2 This is an internal structure diagram of the relay provided by this utility model; Figure 3 This is a schematic diagram of the relay package provided by this utility model. Detailed Implementation

[0020] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] like Figures 1 to 3 As shown, this application provides a withstand voltage relay for insulation detection, including: a primary-side drive module, an optocoupler control module 1, a conduction module 2, and a withstand voltage enhancement module 3.

[0022] Specifically, the primary-side driving module includes a light-emitting diode (LED), whose anode and cathode are respectively connected to a control signal source; the optocoupler control module 1 includes a photosensitive switch, whose control terminal is connected to the LED via an optocoupler; the conduction module 2 includes a first terminal and a second terminal of the photosensitive switch, which respectively constitute the input and output terminals of the relay; the withstand voltage enhancement module 3 includes two resistors, which are respectively connected between the first terminal and the second terminal and are connected in parallel with the conduction path of the photosensitive switch; wherein: when the photosensitive switch is in the conducting state, a low-impedance path is formed between the first terminal and the second terminal, and the current bypasses the resistor; when the photosensitive switch is in the off state, the resistor forms a conduction path with a fixed resistance value, which is used to share the disconnection voltage of the relay in the high-voltage circuit.

[0023] This implementation uses optocouplers to control a secondary-side photosensitive switching device (such as a Photomos) to switch the voltage path. When the primary-side LED receives a control signal current (e.g., 10mA), it generates a light signal that turns on the secondary-side MOSFET, forming a low-impedance path between the relay input and output. Current flows primarily through the MOSFET's conduction path, bypassing the parallel resistors. When there is no control signal, the photosensitive switching device is off. At this time, the two series resistors form a path with a fixed resistance value (e.g., a total resistance of 1MΩ) to withstand and share the disconnection voltage under high-voltage conditions, reducing the risk of device breakdown and thus improving the overall voltage withstand performance of the relay.

[0024] The resistor, with a resistance of 0.5MΩ, provides a stable voltage divider path when the switching device is open, limiting the voltage across the relay to within 1 / 5 of the original system voltage in the open state. Setting the resistor value to 0.5MΩ helps to form a reliable high-resistance isolation path when the relay is open, while ensuring stable voltage division capability under high-voltage conditions. The voltage division capability of the resistor network not only significantly reduces the voltage withstand requirements of the switching device, but also suppresses high-voltage surges in the event of a sudden short circuit to ground, extending device life and improving overall system reliability.

[0025] The photosensitive switching device is a MOSFET, with a resistor connected between its drain and source via gold wire bonding. In the package design, the resistor is directly connected in parallel between the source and drain of the MOSFET via gold wire bonding, creating a parallel relationship between the resistance and the dominant conduction path. This structure ensures that when the MOSFET is off, current can flow through the resistor to form an alternative path, achieving a voltage divider function; while when the MOSFET is on, the low-resistance path dominates the current flow, and the resistor is bypassed, avoiding unnecessary power loss. The connection method achieved through gold wire bonding has low inductance and low resistance characteristics, and improves the device's structural compactness and conduction reliability.

[0026] The resistor is formed on the surface of an aluminum nitride (AlN) ceramic substrate using a thick-film laser etching process. The MOSFET chip is soldered to the resistor's terminal electrodes, and the two are connected via eutectic bonding to form a secondary structure. This structure integrates the resistor and MOSFET onto a single AlN ceramic substrate, significantly improving the module's integration density and thermal stability. The thick-film laser etching process enables precise control of the resistance value, improving resistance consistency and reliability. The high thermal conductivity of the AlN substrate facilitates rapid heat dissipation, preventing MOSFET performance degradation due to heat accumulation and enhancing the device's withstand voltage and long-term stability. The eutectic bonding process ensures stable connections, avoiding cold solder joints or thermal fatigue damage. This overall structure is suitable for high-voltage, high-frequency applications, such as insulation detection modules in energy storage systems.

[0027] The resistor's temperature drift coefficient does not exceed ±25ppm / ℃, and its power rating is 0.25W. This ensures that the resistance change is less than 1% under long-term operation in a high-voltage environment, guaranteeing the voltage division accuracy and consistency of the relay in the open state, thereby improving the accuracy and reliability of insulation impedance detection.

[0028] like Figure 2 and Figure 3 As shown, the relay is packaged in an SMD-5 package. Its secondary switch port withstand voltage is not less than DC600V, and the isolation withstand voltage between the primary and secondary sides reaches 5000Vrms / min, which is used to meet the ground insulation requirements of different potentials in the energy storage system.

[0029] A resistor and a photosensitive switch form a secondary bridge arm structure, connected in the detection path between the positive or negative terminal of the battery cluster and the PE ground. Changes in the voltage across the resistor reflect changes in the insulation impedance of the positive or negative terminal to ground. This structure enables dynamic monitoring of the battery cluster's insulation to ground and is suitable for identifying positive or negative grounding faults. Resistive voltage division achieves electrical isolation and voltage reduction under high-voltage paths, improving detection safety and system stability. Simultaneously, the secondary bridge arm structure simplifies the insulation detection circuit, facilitating system integration and modular design.

[0030] The photosensitive switching device has an on-state impedance of no more than 1Ω and an off-state impedance of more than 0.5MΩ to achieve effective isolation and switching of the voltage path. This design significantly enhances the electrical isolation performance and control accuracy of the relay. The low on-state impedance helps reduce energy loss, improve conduction efficiency, and reduce device heating; the high off-state impedance ensures good electrical isolation in high-voltage systems, avoiding detection errors or device damage due to leakage current.

[0031] The operating current of the light-emitting diode is 5mA to 15mA. Controlling the luminous intensity of its primary side adjusts the reliability of the secondary side's conduction. This adjustment mechanism, while ensuring conduction reliability, also enhances the system's adaptability to environmental changes (such as temperature rise and aging), and is a key means to improve the reliability and lifespan of optocoupler relays.

[0032] The relay is installed in the insulation detection bridge arm circuit. When the energy storage system experiences a PE short-circuit fault, the voltage is reduced to below 400V across the relay via a voltage divider formed by the resistors in the voltage-enhancing module 3, according to the following formula. In this embodiment, a relay with a voltage-enhancing structure is integrated into the insulation detection bridge arm circuit of the energy storage system. The bridge arm is connected between the positive or negative terminal of the battery cluster and the PE ground. Under normal conditions, the relay is either on or off, and path switching is achieved by combining the characteristics of the photosensitive switching device and the parallel resistor. When a ground short-circuit fault occurs, such as a short circuit between the positive terminal and PE, a high system voltage (e.g., DC 2000V) will be applied across the bridge arm containing the relay. At this time, through the voltage divider network constructed by the parallel resistors in the voltage-enhancing module 3, according to the voltage division formula: V k =V sys ×R 并联 / (R) 采样 +R 分压 +R 并联 ); where R 并联 A resistor is connected in parallel to the bridge arm ( Figure 1 In the middle, R5 and R6, R5=R6=0.5MΩ); R 采样 For voltage sampling resistor ( Figure 1 In the middle, R1 and R4, R1=R4=5kΩ), R 分压 For additional voltage divider resistors ( Figure 1 With R2 and R3 (R2=R3=4MΩ), the voltage across the relay terminals can be limited to below 400V, which is much lower than the system voltage.

[0033] The above description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A withstand voltage relay for insulation testing, characterized in that, include: The primary-side driving module includes a light-emitting diode, whose anode and cathode are respectively connected to a control signal source; The optocoupler control module (1) includes a photosensitive switch device, the control terminal of which is connected to the light-emitting diode via an optocoupler; The conducting module (2) includes the first terminal and the second terminal of the photosensitive switching device, which respectively constitute the input terminal and the output terminal of the relay; The withstand voltage enhancement module (3) includes two resistors, which are respectively connected between the first terminal and the second terminal, and are connected in parallel with the conduction path of the photosensitive switch device; in: When the photosensitive switch is in the on state, a low-impedance path is formed between the first terminal and the second terminal, and the current bypasses the resistor. When the photosensitive switch is in the off state, the resistor forms a conducting path with a fixed resistance value to share the disconnection voltage of the relay in the high-voltage circuit.

2. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The resistor has a resistance of 0.5MΩ and is used to provide a stable voltage divider path when the switching device is disconnected, so that the voltage across the relay is limited to less than 1 / 5 of the original system voltage in the disconnected state.

3. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The photosensitive switching device is a MOSFET, and its drain and source are connected to the resistor by gold wire bonding.

4. The withstand voltage relay for insulation testing as described in claim 3, characterized in that, The resistor is formed on the surface of an aluminum nitride (AlN) ceramic substrate using a thick-film laser etching process. The MOSFET chip is soldered to the resistor terminal electrode and connected by eutectic bonding to form a secondary side structure.

5. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The temperature drift coefficient of the resistor does not exceed ±25ppm / ℃, and the power rating is 0.25W, to ensure that the resistance change is less than 1% under long-term operation in a high-voltage environment.

6. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The relay is packaged in an SMD-5 type package, with a secondary switch port withstand voltage of not less than DC600V and an isolation withstand voltage between the primary and secondary sides of 5000Vrms / min, to meet the ground insulation requirements of different potentials in the energy storage system.

7. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The resistor and the photosensitive switch form a secondary bridge arm structure and are connected in the detection path between the positive or negative terminal of the battery cluster and the PE ground. The change in voltage on the resistor is detected to reflect the change in the insulation impedance of the positive or negative terminal to ground.

8. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The photosensitive switch has an impedance of no more than 1Ω in the on-state and an impedance of more than 10MΩ in the off-state, so as to achieve effective isolation and switching of the voltage path.

9. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The operating current of the light-emitting diode is 5mA to 15mA, and the light intensity of its primary side is controlled to achieve the adjustment of the reliability of the secondary side conduction.

10. The withstand voltage relay for insulation testing as described in claim 1, characterized in that, The relay is installed in the insulation detection bridge arm circuit, and when the energy storage system encounters a PE short circuit fault, the maximum withstand voltage at both ends of the relay is reduced to less than 400V through the voltage divider of the withstand voltage enhancement module (3) according to the following formula.

Images