Improved XY capacitor plate and failure protection method thereof

Abstract

The invention discloses an improved XY capacitor plate, and belongs to the field of electronic circuits, the improved XY capacitor plate comprises an X capacitor connected in parallel between a live wire and a zero line, and a first Y capacitor and a second Y capacitor respectively connected between the live wire and a ground wire and between the zero line and the ground wire, and the first Y capacitor and the second Y capacitor adopt symmetrical design and jointly form a pi-type filtering structure; compared with the prior art, differential mode and common mode noise can be efficiently suppressed, the harsh EMC requirement of a ship is met, the safety and reliability of the circuit are greatly improved through the application of the safety capacitor and the redundancy design of the Y capacitor, the electric shock risk caused by element failure is avoided, and part of the filtering function can still be reserved when a single point of fault occurs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic circuits, and in particular, relates to an improved XY capacitor plate and a failure protection method thereof. BACKGROUND

[0002] When a ship motor controller is working, the switching devices such as inverters inside it will generate high-frequency noise. These noises will be conducted and radiated along the motor line and high-voltage power line, forming electromagnetic interference (EMC). The ship power grid system has its particularity, and is usually an isolated grid with limited generator capacity. Therefore, the requirements for the grid harmonic pollution and electromagnetic interference generated by frequency converters and other devices are extremely strict.

[0003] The EMC filtering schemes adopted by existing ordinary industrial motor controllers have many deficiencies when applied to ship environments. First, their EMC suppression capability often fails to meet the stringent standards of ship operation. Second, these schemes do not fully consider the special requirements of ship operation for safety redundancy, maintainability, and modularity in design. For example, when an ordinary capacitor fails, a short circuit may occur, causing fire or electric shock risks, and after a single component fails, the entire filtering function may be completely lost, without redundancy.

[0004] Therefore, how to design an EMC filtering circuit that can not only meet the strict EMC performance requirements of ships, but also solve the problem of leakage current and has high safety, redundancy, and maintainability, is a technical problem that needs to be solved in the field. SUMMARY

[0005] To overcome the above defects, the present application provides an improved XY capacitor plate, comprising: an X capacitor, used for being connected in parallel between the live line and the neutral line of an alternating current power supply; a first Y capacitor, used for being connected between the live line and the ground line; a second Y capacitor, used for being connected between the neutral line and the ground line; The first Y capacitor and the second Y capacitor are designed symmetrically, and the X capacitor, the first Y capacitor, and the second Y capacitor are all safety capacitors, and their preset failure mode is open circuit.

[0006] Further, the X capacitor is an X1 safety capacitor, and the first Y capacitor and the second Y capacitor are Y1 safety capacitors.

[0007] Further, the capacitance of the X capacitor is 0.47 µF, and the withstand voltage is 305 V; The capacitance of the first Y capacitor and the second Y capacitor is 0.1 µF, and the withstand voltage is 300 V.

[0008] The application also discloses a failure protection method based on the improved XY capacitor plate. a) using the X capacitor to provide a parallel low-impedance loop for differential mode noise flowing between the live wire and the zero wire; b) using the first Y capacitor and the second Y capacitor with symmetric design to provide a ground discharge path for common mode noise on the live wire and the zero wire respectively; c) when any of the X capacitor, the first Y capacitor or the second Y capacitor fails, using the open-circuit failure mode characteristics to make the failed capacitor in an open-circuit state on the circuit to prevent short circuit of the power supply; d) when any of the first Y capacitor or the second Y capacitor fails in an open-circuit mode, using the other non-failed Y capacitor to continue to provide a common mode noise discharge path for the corresponding line to realize redundancy protection.

[0009] Compared with the prior art, the application has the following beneficial effects: 1. The design of the capacitor plate (using an approval capacitor) directly determines the feasibility of the failure protection method (open-circuit failure), which fundamentally eliminates the risk of short circuit, fire or electric shock caused by component damage; 2. The failure protection method clearly uses healthy components in the symmetric design to continue to provide protection when partial failure occurs, which is a redundancy feature that ordinary filter circuits do not have, greatly improving the reliability of the system; 3. The π-type structure and symmetric design of the filter performance excellent capacitor plate ensure balanced and efficient suppression of differential mode and common mode noise. DETAILED DESCRIPTION

[0010] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application. EMBODIMENT

[0011] The embodiment provides an improved XY capacitor plate adopting a π-type filter structure, the input end of which is a live wire and a zero wire of an alternating current power supply, and the output end is connected to a main circuit of a motor controller, and core components on the capacitor plate include: an X capacitor connected in parallel between the live wire and the zero wire; two Y capacitors, namely a first Y capacitor and a second Y capacitor, wherein the first Y capacitor is connected between the live wire and a ground wire, and the second Y capacitor is connected between the zero wire and the ground wire, and the two Y capacitors are symmetrically designed to ensure the balance of filtering.

[0012] In the specific selection of elements, the present embodiment makes an optimized selection to achieve the best performance and safety: Safety class: X capacitor selects X1 level, two Y capacitors select Y1 level, which ensures that the capacitor plate can withstand high voltage impact, and its preset failure mode is open circuit; Capacity and voltage resistance: the capacity of the X capacitor is preferably 0.47µF, and the voltage resistance is 305V; the capacity of the first and second Y capacitors is preferably 0.1µF, and the voltage resistance is 300V.

[0013] In addition, the Y capacitor in the present embodiment also undertakes the important function of handling leakage current. In any alternating current system, the current flowing through the capacitor follows the formula I=2πfCV (where f is the frequency, C is the capacity, and V is the voltage), so when the system is working, there will be a small current continuously flowing through the Y capacitor into the ground. By selecting a suitable Y capacitor capacity (0.1µF), the present embodiment controls the leakage current within the safety standard range, thereby avoiding the problem of electric shock or causing the leakage protector (RCD / GFCI) to malfunction when the human body touches the device shell. Embodiment

[0014] The present embodiment is based on the failure protection method of the improved XY capacitor plate in embodiment 1, including a normal working stage and a fault response stage, as follows: Normal working stage, in this stage, all elements of the capacitor plate are intact, and the core filtering and protection functions are executed: Differential mode noise filtering: when the system is powered on and high-frequency differential mode noise is generated in the circuit due to inverter switches, etc., the differential mode noise current flows back and forth between the live line and the neutral line. Therefore, through the capacitor plate structure in embodiment 1, i.e. the X capacitor is connected in parallel between the live line and the neutral line, for high-frequency differential mode noise, the X capacitor (0.47µF) presents very low impedance, therefore, the noise current will form a low-impedance loop through the X capacitor, and cannot enter the power grid or the subsequent circuit, thereby realizing differential mode filtering, which is step a); Common mode noise filtering and leakage current handling: when the system is powered on and common mode noise exists in the circuit, since the common mode noise current exists on the live line and the neutral line at the same time and in the same direction, both returning to the ground, therefore, through the capacitor plate structure in embodiment 1, i.e. two symmetrical Y capacitors are respectively located between the live line and the ground and between the neutral line and the ground, for high-frequency common mode noise, the Y capacitors (0.1µF) present low impedance, therefore, the common mode noise current on the live line and the neutral line will be directly discharged to the ground through the two Y capacitors, without being emitted outward through the power line, thereby realizing common mode filtering, at the same time, the two Y capacitors also provide a controlled leakage current discharge path that meets the safety standards for the system, which is step b); The fault response stage, in which the components on the capacitor plate fail, the system automatically enters the failure protection and redundancy working mode, and the fault scenarios are divided into three cases: open circuit failure protection, X capacitor failure and Y capacitor single point failure. Open circuit failure protection: when any one of the safety capacitors (X capacitor or Y capacitor) on the capacitor plate fails (based on the physical characteristics of the safety capacitor, its failure mode is open circuit. Compared with the short circuit that may occur when a normal capacitor fails, the safety capacitor can effectively reduce the risk of fire or electric shock), the failed component is automatically disconnected from the circuit, which fundamentally eliminates the chain failure or safety accident caused by component short circuit, and is the basic prerequisite for safe response to all subsequent fault scenarios; X capacitor failure: when the X capacitor fails and is open, the differential mode filtering function of the XY capacitor plate is completely lost, at this time, the product cannot pass the EMC test, and the differential mode noise will exceed the standard. However, because the capacitor is in an open state, the product will not have the risk of electric shock or fire, and no operation is required, the system can still work normally, but the EMI performance will be reduced; Y capacitor single point failure: when any one of the two Y capacitors (for example, the first Y capacitor on the live line) fails and is open, the common mode noise on the live line loses the discharge path, the filtering effect will decrease, and the common mode noise suppression becomes unbalanced. In the safety design of the present embodiment, redundancy is provided: if one Y capacitor fails and is open, the other Y capacitor still works, and the system still retains part of the common mode filtering capability, rather than completely losing it, which is step d). Although the product cannot pass the EMI test, because the failed Y capacitor is equivalent to being disconnected from the circuit, it will not cause the live line or zero line to be directly connected to the ground, so the product will not have the risk of electric shock or electric shock. At the same time, the system has higher reliability due to the redundancy design.

[0015] Steps a) and b): normal working process (filtering and leakage current processing) During normal operation, the capacitor plate performs the following functions: Differential mode filtering: differential mode noise current flows between the live line and the zero line. According to step a), the X capacitor (0.47µF) provides a very low parallel impedance path for high-frequency differential mode noise, preventing the noise current from entering the subsequent circuit, thereby achieving differential mode filtering.

[0016] Common mode filtering and leakage current processing: common mode noise current exists in both the live line and the zero line and returns to the ground. According to step b), the two symmetrical Y capacitors (0.1µF) provide a low-impedance discharge path for high-frequency common mode noise to the ground, achieving common mode filtering. At the same time, these two Y capacitors also provide a controlled leakage current path for the system, safely guiding the leakage current to the ground.

[0017] Step c) : General fail-safe procedure When any one of the safety capacitors (X or Y capacitors) on the board fails due to aging, overvoltage, etc., step c) is executed. Due to its inherent open-circuit failure mode, the failed capacitor is automatically disconnected from the circuit and no short circuit is formed. This step effectively reduces the risk of fire or electric shock. For example, when the X capacitor opens, the differential mode filtering function fails and the product EMC performance is degraded, but the system can still work safely.

[0018] Step d) : Redundant protection procedure When one of the two Y capacitors (e.g. the first Y capacitor on the live line) fails open, step d) is executed. At this time, the common mode noise on the live line loses the discharge path and the filtering effect will be reduced and unbalanced. However, because the failed capacitor is disconnected, there is no risk of electric shock. More importantly, the redundant design of this solution is realized: the other non-failed Y capacitor (the second Y capacitor on the neutral line) still works normally, and the system therefore retains some common mode filtering capability, rather than completely losing it. This step ensures high reliability of the system under single point failure, especially suitable for unattended or inconvenient-to-maintain ship environments.

[0019] It should be noted that the structure described in the present application can be implemented in many different forms, and is not limited to the embodiments described, and any equivalent transformation made by those of ordinary skill in the art using the content of the present application, or direct or indirect application in other related technical fields, such as other loading and unloading of articles, are all within the scope of protection of the present application.

Claims

1. An improved XY capacitor board, characterized in that, include: An X capacitor is used to connect in parallel between the live wire and the neutral wire of the AC power supply; A first Y capacitor is used to connect between the live wire and the ground wire; A second Y capacitor is used to connect between the neutral wire and the ground wire; The first Y capacitor and the second Y capacitor adopt a symmetrical design. The X capacitor, the first Y capacitor and the second Y capacitor are all safety capacitors, and their preset failure mode is open circuit.

2. The improved XY capacitor board as described in claim 1, characterized in that: The X capacitor is an X1-level safety capacitor, and the first Y capacitor and the second Y capacitor are Y1-level safety capacitors.

3. An improved XY capacitor board as described in claim 2, characterized in that: The X capacitor has a capacitance of 0.47µF and a voltage rating of 305V; The capacitance of the first Y capacitor and the second Y capacitor is 0.1µF, and the voltage rating is 300V.

4. A failure protection method based on the improved XY capacitor board according to claim 1, characterized in that, Includes the following steps: a) Using the X capacitor, a parallel low-impedance loop is provided for differential-mode noise flowing between the live and neutral wires; b) The first Y capacitor and the second Y capacitor, which are designed symmetrically, provide a path to ground for common-mode noise on the live wire and the neutral wire, respectively. c) When any one of the X capacitor, the first Y capacitor or the second Y capacitor fails, the characteristics of its open-circuit failure mode are utilized to make the failed capacitor open-circuit in the circuit to prevent the power supply from short-circuiting. d) When either the first Y capacitor or the second Y capacitor fails to open circuit, the other unfailed Y capacitor continues to provide a common-mode noise discharge path for the corresponding line to achieve redundant protection.