Fault detection device for output relay of direct current charging system

Abstract

The utility model belongs to the technical field of direct-current charging, and discloses a fault detection device of an output relay of a direct-current charging system, which is characterized in that a pin 3 of an operational amplifier U1 is connected with one end of a resistor R1 and one end of a resistor R3, the other end of the resistor R1 is connected with a port c, the other end of the resistor R3 is connected with a port GND, a pin 2 of the operational amplifier U1 is connected with one end of a resistor R2 and one end of a resistor R15, and the other end of the resistor R2 is connected with the port GND. The other end of the resistor R2 is connected with the port d, the pin 1 of the operational amplifier U1 is connected with one end of the resistor R7 and the other end of the resistor R15, the other end of the resistor R7 is connected with one end of the capacitor C2 and the port UCD, and the other end of the capacitor C2 is connected with the port GND. The beneficial effects of the utility model are that the fault state of the relay is judged by detecting the voltages at the front end and the rear end of the main contact of the output relay and is judged by combining the state of the auxiliary contact of the output relay, thereby improving the reliability.

Description

Technical Field

[0001] The utility model relates to the technical field of direct current charging, in particular to a fault detection device for an output relay of a direct current charging system. Background Art

[0002] According to the requirements in Appendix B of GB / T18487.1-2015 "Electric Vehicle Conductive Charging System Part 1: General Requirements", the output relay of the DC charging system must have a fault detection function. Currently, there are relays with auxiliary contacts and without auxiliary contacts on the market. Relays with auxiliary contacts have two signal lines that feedback the relay status. These two signal lines are connected to the two ends of a micro switch inside the relay. The micro switch is connected to the mechanical structure of the relay. When the relay is closed or disconnected, it will drive the micro switch to close and disconnect. The state of the micro switch can be used to know whether the relay is faulty. However, this mechanical structure connection is unreliable in actual use. The state of the micro switch cannot timely feedback the state of the relay. This may be related to the batch consistency and travel of the mechanical structure design. In actual use, there are occasional situations where the state of the micro switch cannot correctly feedback the action state of the relay, which will affect the safety of the DC charging system.

[0003] Therefore, it is necessary to provide a fault detection device for the output relay of a DC charging system, which can accurately detect the fault state of the output relay and make up for the unreliable disadvantage of the auxiliary contact. Utility Model Content

[0004] The utility model discloses a fault detection device for an output relay of a direct current charging system, relates to the field of direct current charging systems for electric vehicles, and can effectively solve the technical problems involved in the background technology.

[0005] To achieve the above purpose, the technical solution of the utility model is:

[0006] A fault detection device for an output relay of a DC charging system. The DC charging system comprises a port a, a port b, a port c, a port d, a relay K1 and a relay K2. The port a is connected to the port c via a main contact K1-1 of the relay K1, and the port b is connected to the port d via a main contact K2-1 of the relay K2. The fault detection device comprises an operational amplifier U1, an operational amplifier U2, a transistor Q1 and a transistor Q2.

[0007] Pin 3 of the operational amplifier U1 is connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the port c, the other end of the resistor R3 is connected to the port GND, pin 2 of the operational amplifier U1 is connected to one end of the resistor R2 and one end of the resistor R15, the other end of the resistor R2 is connected to the port d, pin 1 of the operational amplifier U1 is connected to one end of the resistor R7 and the other end of the resistor R15, the other end of the resistor R7 is connected to one end of the capacitor C2 and the port UCD, and the other end of the capacitor C2 is connected to the port GND.

[0008] Pin 3 of the operational amplifier U2 is connected to one end of the resistor R5 and one end of the resistor R6, the other end of the resistor R5 is connected to the port a, the other end of the resistor R6 is connected to the port GND, pin 2 of the operational amplifier U2 is connected to one end of the resistor R4 and one end of the resistor R16, the other end of the resistor R4 is connected to the port b, pin 1 of the operational amplifier U2 is connected to one end of the resistor R8 and the other end of the resistor R16, the other end of the resistor R8 is connected to one end of the capacitor C1 and the port UAB, and the other end of the capacitor C1 is connected to the port GND.

[0009] The collector of the transistor Q1 is connected to port K2_STATE and one end of the resistor R11, the other end of the resistor R11 is connected to port VCC2, the emitter of the transistor Q1 is connected to one end of the resistor R10, one end of the capacitor C3 and port GND, the base of the transistor Q1 is connected to the other end of the resistor R10, the other end of the capacitor C3 and one end of the resistor R9, the other end of the resistor R9 is connected to one end of the auxiliary contact K2-2 of the relay K2, and the other end of the auxiliary contact K2-2 is connected to port VCC1.

[0010] The collector of the transistor Q2 is connected to port K1_STATE and one end of the resistor R12, the other end of the resistor R12 is connected to port VCC2, the emitter of the transistor Q2 is connected to one end of the resistor R14, one end of the capacitor C4 and port GND, the base of the transistor Q2 is connected to the other end of the resistor R14, the other end of the capacitor C4 and one end of the resistor R13, the other end of the resistor R13 is connected to one end of the auxiliary contact K1-2 of the relay K1, and the other end of the auxiliary contact K1-2 is connected to port VCC1.

[0011] The port UAB, the port UCD, the port K1_STATE and the port K2_STATE are connected to the controller MCU.

[0012] The fault state of the relay is judged by detecting the voltage at the front and rear ends of the main contact of the output relay. If the relay is closed, the voltage at the front and rear ends of the relay is the same. If there is a big difference, it means that the relay is not closed. If the relay is disconnected, the voltage at the front and rear ends of the relay is the same, which means that the relay is stuck. At the same time, the state of the auxiliary contacts of the output relay is combined to improve reliability.

[0013] As a preferred improvement of the present invention: the port VCC1 is connected to a 12V or 3.3V power supply.

[0014] As a preferred improvement of the present invention: the port VCC2 is connected to a 3.3V power supply.

[0015] As a preferred improvement of the present invention: the port a is connected to the output positive pole of the DC charging system, the port b is connected to the output negative pole of the DC charging system, the port c receives the positive end of the charging device, and the port d receives the negative end of the charging device.

[0016] As a preferred improvement of the present invention: the models of the operational amplifier U1 and the operational amplifier U2 are LM2904.

[0017] As a preferred improvement of the utility model: the controller MCU model is AT32F435ZMT7, the port UAB is connected to pin 34, the port UCD is connected to pin 26, the port K1_STATE is connected to pin 36, and the port K2_STATE is connected to pin 35.

[0018] The beneficial effects of the utility model are as follows:

[0019] A device for detecting faults of output relays of a DC charging system with high reliability is provided. The device does not completely rely on the auxiliary contacts of the relay itself for fault detection. The device is more accurate than the detection method of the auxiliary contacts of the relay itself. The fault state of the relay is judged by detecting the voltage at the front and rear ends of the main contacts of the output relay, and the fault state of the relay is judged in combination with the state of the auxiliary contacts of the output relay, thereby improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0021] Figure 1 It is a schematic diagram of a fault detection device for an output relay of a DC charging system according to the utility model;

[0022] Figure 2 This is a schematic diagram of the detection principle of the utility model;

[0023] Figure 3 Amplification of the detection principle of this utility model Figure 1 ;

[0024] Figure 4 Amplification of the detection principle of this utility model Figure 2 . DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0026] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0027] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] See also Figure 1 As shown, the utility model provides a fault detection device for an output relay of a DC charging system. The DC charging system includes port a, port b, port c, port d, relay K1 and relay K2. The port a is connected to the port c through the main contact K1-1 of the relay K1, and the port b is connected to the port d through the main contact K2-1 of the relay K2. The port a is connected to the output positive pole of the DC charging system, the port b is connected to the output negative pole of the DC charging system, the port c receives the positive end of the charging device, and the port d receives the negative end of the charging device. The fault detection device includes an operational amplifier U1, an operational amplifier U2, a transistor Q1 and a transistor Q2. Specifically, the current of the DC charging system flows from ab to cd, and the cd end is connected to the charging device (electric vehicle, etc.). Relay K1 and relay K2 are used to control the on and off of the circuit, and are respectively connected to corresponding controllers, auxiliary power supplies, etc. for control. The fault detection device is used to detect the voltages of the front and rear ends Uab and Ucd of the relay, as well as the voltage of the auxiliary contacts, and then judge the fault condition of the relay.

[0031] Pin 3 of the operational amplifier U1 is connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the port c, the other end of the resistor R3 is connected to the port GND, pin 2 of the operational amplifier U1 is connected to one end of the resistor R2 and one end of the resistor R15, the other end of the resistor R2 is connected to the port d, pin 1 of the operational amplifier U1 is connected to one end of the resistor R7 and the other end of the resistor R15, the other end of the resistor R7 is connected to one end of the capacitor C2 and the port UCD, and the other end of the capacitor C2 is connected to the port GND. Pin 3 of the operational amplifier U2 is connected to one end of the resistor R5 and one end of the resistor R6, the other end of the resistor R5 is connected to the port a, the other end of the resistor R6 is connected to the port GND, pin 2 of the operational amplifier U2 is connected to one end of the resistor R4 and one end of the resistor R16, the other end of the resistor R4 is connected to the port b, pin 1 of the operational amplifier U2 is connected to one end of the resistor R8 and the other end of the resistor R16, the other end of the resistor R8 is connected to one end of the capacitor C1 and the port UAB, the other end of the capacitor C1 is connected to the port GND. In this embodiment, the models of the operational amplifier U1 and the operational amplifier U2 are LM2904, and the voltages of Uab and Ucd are detected by the operational amplifier, the resistor and the capacitor. The operational amplifier itself is also connected to the basic circuits such as the auxiliary power supply, which will not be described here.

[0032] The collector of the transistor Q1 is connected to port K2_STATE and one end of the resistor R11, the other end of the resistor R11 is connected to port VCC2, the emitter of the transistor Q1 is connected to one end of the resistor R10, one end of the capacitor C3 and port GND, the base of the transistor Q1 is connected to the other end of the resistor R10, the other end of the capacitor C3 and one end of the resistor R9, the other end of the resistor R9 is connected to one end of the auxiliary contact K2-2 of the relay K2, and the other end of the auxiliary contact K2-2 is connected to port VCC1. The collector of the transistor Q2 is connected to the port K1_STATE and one end of the resistor R12, the other end of the resistor R12 is connected to the port VCC2, the emitter of the transistor Q2 is connected to one end of the resistor R14, one end of the capacitor C4 and the port GND, the base of the transistor Q2 is connected to the other end of the resistor R14, the other end of the capacitor C4 and one end of the resistor R13, the other end of the resistor R13 is connected to one end of the auxiliary contact K1-2 of the relay K1, the other end of the auxiliary contact K1-2 is connected to the port VCC1, the port UAB, the port UCD, the port K1_STATE and the port K2_STATE are connected to the controller MCU. The port VCC1 is connected to a 12V or 3.3V power supply, the port VCC2 is connected to a 3.3V power supply, and the controller MCU model is AT32F435ZMT7. The controller MCU is connected to the controller of the relay and to four detection ports. It determines whether the relay is faulty by adjusting the on / off of relay K1 and relay K2 and the voltage difference of the four detection terminals.

[0033] K1 and K2 are relays used to cut off the charging circuit at the output end of the DC charging system. K1-1 / K2-1 are the main contacts of the relay, K1-2 / K2-2 are the auxiliary contacts of the relay, Uab is the voltage at the output end of the charging module, and Ucd is the battery voltage at the vehicle end. Uab and Ucd are sampled by the isolation amplifier, and the isolation amplifier outputs the signals UAB and UDC after RC filtering to sample the AD port of the MCU. When K1 / K2 is disconnected, the auxiliary contacts of K1 / K2 are disconnected, the transistors Q1 / Q2 are cut off, K1_STATE / K2_STATE is high level, K1 / K2 is closed, the auxiliary contacts of K1 / K2 are closed, Q1 / Q2 is turned on, and K1_STATE / K2_STATE is low level. The fault state of the relay is judged by detecting the voltage at the front and rear ends of the main contacts of the output relay, and combined with the state of the auxiliary contacts of the output relay to judge, which improves reliability.

[0034] The relay fault detection period is performed before the DC charging insulation test. If the relay is detected to be faulty, the insulation test will not be performed. The relay fault detection logic is shown in Table 1 and the flow chart is shown in Figure 2-Figure 4As shown. Among them, 1: represents K1, K2 closed, 0: represents K1, K2 open. Uab: module output voltage, Ucd: vehicle-end battery voltage.

[0035] Table 1: K1, K2 fault detection logic table

[0036]

[0037]

[0038] Although the implementation scheme of the utility model has been disclosed as above, it is not limited to the applications listed in the specification and the implementation scheme. It can be fully applied to various fields suitable for the utility model. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A fault detection device for an output relay of a DC charging system, the DC charging system comprising port a, port b, port c, port d, relay K1 and relay K2, the port a being connected to the port c via the main contact K1-1 of the relay K1, the port b being connected to the port d via the main contact K2-1 of the relay K2, characterized in that: The fault detection device includes an operational amplifier U1, an operational amplifier U2, a transistor Q1 and a transistor Q2; Pin 3 of the operational amplifier U1 is connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the port c, the other end of the resistor R3 is connected to the port GND, pin 2 of the operational amplifier U1 is connected to one end of the resistor R2 and one end of the resistor R15, the other end of the resistor R2 is connected to the port d, pin 1 of the operational amplifier U1 is connected to one end of the resistor R7 and the other end of the resistor R15, the other end of the resistor R7 is connected to one end of the capacitor C2 and the port UCD, the other end of the capacitor C2 is connected to the port GND; Pin 3 of the operational amplifier U2 is connected to one end of the resistor R5 and one end of the resistor R6, the other end of the resistor R5 is connected to the port a, the other end of the resistor R6 is connected to the port GND, pin 2 of the operational amplifier U2 is connected to one end of the resistor R4 and one end of the resistor R16, the other end of the resistor R4 is connected to the port b, pin 1 of the operational amplifier U2 is connected to one end of the resistor R8 and the other end of the resistor R16, the other end of the resistor R8 is connected to one end of the capacitor C1 and the port UAB, the other end of the capacitor C1 is connected to the port GND; The collector of the transistor Q1 is connected to the port K2_STATE and one end of the resistor R11, the other end of the resistor R11 is connected to the port VCC2, the emitter of the transistor Q1 is connected to one end of the resistor R10, one end of the capacitor C3 and the port GND, the base of the transistor Q1 is connected to the other end of the resistor R10, the other end of the capacitor C3 and one end of the resistor R9, the other end of the resistor R9 is connected to one end of the auxiliary contact K2-2 of the relay K2, and the other end of the auxiliary contact K2-2 is connected to the port VCC1; The collector of the transistor Q2 is connected to the port K1_STATE and one end of the resistor R12, the other end of the resistor R12 is connected to the port VCC2, the emitter of the transistor Q2 is connected to one end of the resistor R14, one end of the capacitor C4 and the port GND, the base of the transistor Q2 is connected to the other end of the resistor R14, the other end of the capacitor C4 and one end of the resistor R13, the other end of the resistor R13 is connected to one end of the auxiliary contact K1-2 of the relay K1, and the other end of the auxiliary contact K1-2 is connected to the port VCC1; The port UAB, the port UCD, the port K1_STATE and the port K2_STATE are connected to the controller MCU.

2. A fault detection device for an output relay of a DC charging system according to claim 1, characterized in that: The port VCC1 is connected to a 12V or 3.3V power supply.

3. The fault detection device for the output relay of a DC charging system according to claim 1, characterized in that: The port VCC2 is connected to a 3.3V power supply.

4. The fault detection device for the output relay of a DC charging system according to claim 1, characterized in that: The port a is connected to the positive output of the DC charging system, the port b is connected to the negative output of the DC charging system, the port c receives the positive terminal of the charging device, and the port d receives the negative terminal of the charging device.

5. The fault detection device for the output relay of a DC charging system according to claim 1, characterized in that: The models of the operational amplifier U1 and the operational amplifier U2 are LM2904.

6. A fault detection device for an output relay of a DC charging system according to claim 1, characterized in that: The controller MCU model is AT32F435ZMT7.

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