A relay anti-arc circuit and control method

Abstract

The invention provides a relay anti-arcing circuit and a control method. The relay anti-arcing circuit comprises a relay and a relay driving circuit connected to the relay, and also comprises a voltage detection circuit, a central controller and a main power driving circuit; the voltage detection circuit, the central controller and the main power driving circuit are connected in sequence, and the control method comprises: the voltage detection circuit detects a voltage signal in the relay and sends the voltage signal to the central controller, the central processing unit performs logic analysis and judgment according to the received voltage signal, and when an abnormal fault occurs, promptly controls the main power driving circuit to shut down the main power transmission, so that the relay can be disengaged from the contact spring under the condition of zero current or small current, realizes power conversion under normal conditions and rapid protection under abnormal conditions, and improves the reliability of the entire circuit. The detection control scheme proposed by the invention occupies a small space, is low in cost, and can well realize the disconnection of the relay contacts.

Description

Technical Field

[0001] The invention belongs to the technical field of relays, and in particular relates to a relay anti-arcing circuit and a control method. Background Art

[0002] With the rapid development of smart grids and energy interconnection, products that can perform bidirectional conversion and transmission of electric energy have gradually become a market hotspot in this field.

[0003] The power relay is one of the key components of the bidirectional converter, and the reliability of the relay is an important guarantee for the reliability of the converter. When the power relay disconnects the contacts under abnormal conditions, an arc will be drawn between the contact springs, and the energy of the arc will often burn the contact springs or even the entire relay. Therefore, a solution to the relay arcing problem is needed to ensure that the relay can be reliably disconnected under abnormal conditions, thereby improving the reliability of the entire converter. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a relay anti-arcing circuit and a control method, aiming to solve the problem that when the traditional relay disconnects the contacts, the energy generated by arcing is likely to burn the contact spring.

[0005] To solve the above technical problems, the present invention is achieved as follows:

[0006] The first aspect of the present invention provides a relay anti-arcing circuit, comprising a relay and a relay driving circuit connected to the relay, a voltage detection circuit, a central controller and a main power driving circuit; wherein:

[0007] The voltage detection circuit is used to detect the voltage signal of the relay and transmit the voltage signal to the central controller;

[0008] The central controller is used to perform logic analysis and control on the voltage signal, and output a control signal according to the logic analysis result;

[0009] The main power driving circuit is used to close or maintain the current input to the relay according to the control signal.

[0010] Furthermore, an input end of the voltage detection circuit is connected between the relay and the relay driving circuit.

[0011] Furthermore, an input end of the voltage detection circuit is connected to a contact of the relay.

[0012] Furthermore, the contacts include two, the voltage detection circuit includes a first voltage detection circuit and a second voltage detection circuit, the input end of the first voltage detection circuit is connected to one of the contacts, and the input end of the second voltage detection circuit is connected to the other contact.

[0013] Furthermore, the voltage detection circuit includes a voltage-dividing resistor and a filter circuit, one end of the voltage-dividing resistor is the input end of the voltage signal, and the other end of the voltage-dividing resistor is connected to the central controller via the filter circuit.

[0014] Furthermore, the voltage detection circuit is an operational amplifier circuit, or an external hardware comparison circuit.

[0015] Furthermore, the central controller is a DSP control unit, the DSP control unit is provided with at least one voltage sampling AD port or IO port, and the DSP control unit is provided with a PWM drive signal output interface.

[0016] Furthermore, the main circuit controlled by the main power driving circuit is one of a DC-DC converter circuit and an AC-DC converter circuit.

[0017] A second aspect of the present invention provides a control method, which is applied to a relay anti-arcing circuit, wherein the relay anti-arcing circuit includes a relay, a relay drive circuit connected to the relay, a voltage detection circuit, a central controller, and a main power drive circuit, and the control method includes:

[0018] The voltage detection circuit detects the voltage signal of the relay and transmits the voltage signal to the central controller;

[0019] The central controller performs logic analysis and control on the voltage signal, and outputs a control signal according to the logic analysis result;

[0020] The main power driving circuit turns off or maintains the current input to the relay according to the control signal.

[0021] Furthermore, the central controller performs logic analysis and control on the voltage signal, and outputs a control signal according to the logic analysis result, including:

[0022] The central controller calculates a voltage value according to the voltage signal and compares the voltage value with a voltage threshold;

[0023] When the voltage value is greater than the voltage threshold, continue to compare the voltage value duration with the time threshold;

[0024] When the duration is greater than the time threshold, it is determined that the relay fails, and a control signal is output.

[0025] Furthermore, the central controller calculates the voltage value according to the voltage signal and compares the voltage value with the voltage threshold, including:

[0026] The central controller acquires the voltage signal of the relay contact, calculates the voltage value of the relay contact according to the voltage signal, and compares the voltage value with the voltage threshold;

[0027] And / or the central controller acquires the voltage signal of the relay coil, calculates the voltage value of the relay coil according to the voltage signal, and compares the voltage value with the voltage threshold.

[0028] Compared with the prior art, the relay anti-arcing circuit and control method provided by the present invention have the following beneficial effects: the circuit structure provided by the present invention is simple, a voltage detection circuit is provided for the relay, and a central controller is provided to connect the voltage detection circuit. The present invention proposes a control method: the voltage detection circuit detects the voltage signal of the relay and transmits the voltage signal to the central controller; the central controller performs logical analysis and control on the voltage signal, and outputs a control signal according to the result of the logical analysis; the main power drive circuit shuts off or maintains the current input to the relay according to the control signal. The present invention realizes power conversion under normal conditions and rapid protection under abnormal conditions through the detection of the voltage signal by the voltage detection circuit, the logical analysis and judgment of the central controller, and the control of the drive signal of the main power drive circuit by the central controller, thereby improving the reliability of the entire circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 1 is a schematic diagram of the overall structure of the relay anti-arcing circuit in an embodiment of the present invention;

[0030] Figure 2 is a control flow chart for realizing the arc resistance function in an embodiment of the present invention;

[0031] Figure 3 yes Figure 2 A detailed flowchart of realizing the anti-arc function;

[0032] Figure 4 yes Figure 3 The relay contact voltage timing diagram in the control process shown;

[0033] Figure 5 yes Figure 3 The relay coil voltage timing diagram in the control process is shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] In the related art, there are two main solutions to achieve the arc extinguishing function of the relay. The first is to use a contactor or a relay with a built-in magnetic arc extinguishing function. The advantage of this solution is that it is simple and easy, but the cost is too high and the size is too large. The second is to add one or more switching tubes, connected in parallel between the relay contacts, to assist the relay in zero-current disconnection and avoid arcing. The advantage of this solution is that it can well achieve zero-current disconnection of the relay contacts, but it adds switching tubes and drive circuits, the cost is relatively high, and the control is relatively complex.

[0036] Example 1

[0037] like Figure 1 As shown, the first aspect of the present invention provides a relay anti-arcing circuit, including a relay and a driving circuit thereof, and also including a voltage detection circuit, a central controller and a main power driving circuit; wherein,

[0038] A voltage detection circuit is used to detect the voltage signal of the relay and transmit the voltage signal to the central controller;

[0039] The central controller is used to perform logic analysis and control on the voltage signal and output the control signal according to the logic analysis result;

[0040] The main power driving circuit is used to close or maintain the current input to the relay according to the control signal.

[0041] exist Figure 1 As shown, the relay and its driving circuit are divided into one part, in which the voltage detection circuit includes two groups, so Figure 1 The relay anti-arcing circuit shown divides the circuit components of the present application into five parts, namely the relay and its driving circuit, the voltage detection circuit (including two groups), the central controller and the main power driving circuit. The detection control scheme proposed by the present invention is low-cost and can quickly detect and judge relay faults. When an abnormal fault occurs, the main power transmission is shut down in time, so that the relay can be disconnected from the contact spring under zero current or low current conditions, realizing power conversion under normal conditions and rapid protection under abnormal conditions, thereby improving the reliability of the entire circuit.

[0042] Specifically, Figure 1Part_1 is a voltage detection circuit of the power contact of the relay. The relay has two contacts, namely the first contact m and the second contact p. Accordingly, the voltage detection circuit is divided into a first voltage detection circuit and a second voltage detection circuit. The input end of the first voltage detection circuit is connected to the first contact m, and the input end of the second voltage detection circuit is connected to the second contact p, which is used to detect the voltage signals of the two contacts and send the detected voltage signals to the central controller respectively.

[0043] like Figure 1 As shown, as one of the implementation methods of this embodiment, the first voltage detection circuit is composed of a capacitor C1, resistors R1, R4, and R7, and is used to detect the relative voltage value of the first contact m relative to the control ground, wherein the resistor R1 is a voltage-dividing resistor, and the resistors R4, R7 and the capacitor C1 form a filtering circuit. After the voltage of the first contact m is divided by the resistor and filtered, the detection voltage signal is sent to the central controller. The second voltage detection circuit is composed of a capacitor C2, resistors R2, R5, and R8, and is used to detect the relative voltage value of the second contact p relative to the control ground, wherein the resistor R2 is a voltage-dividing resistor, and the resistors R5, R8 and the capacitor C2 form a filtering circuit. After the voltage of the second contact p is divided by the resistor and filtered, the detection voltage signal is sent to the central controller.

[0044] Figure 1 Part 2 shown in the figure is the voltage detection circuit of the relay drive signal. The input end of the voltage detection circuit is connected between the relay and the relay drive circuit, and is used to detect the relative voltage value of the relay coil relative to the ground. The voltage detection circuit is composed of capacitor C3, resistors R3, R6, and R9, where resistor R3 is a voltage divider resistor, and resistors R6, R9 and capacitor C3 form a filter circuit. After the drive signal is divided by resistors and filtered, the detection voltage signal is sent to the central controller.

[0045] It should be noted that the above voltage detection circuits all use a detection method of resistor voltage division. As other implementation methods of this embodiment, other detection methods such as an operational amplifier circuit or an external hardware comparison circuit may also be used.

[0046] Figure 1 Part 3 shown in the figure is a central controller. Preferably, the controller uses a DSP control unit, which is provided with at least one voltage sampling AD port or I0 port, and the DSP control unit is also provided with a PWM drive signal output interface. Figure 1As shown, the DSP control unit is provided with interfaces AD1, AD2 and AD3, which are used for voltage detection of the driving signal of the relay and the voltage detection of the power contact reed of the relay, and is provided with 8-way PWM driving signal output interfaces "PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8" for driving the power switch tube of the main power driving circuit.

[0047] Among them, the voltage difference between the first contact m and the second contact p can be obtained through the operation of the DSP control unit. Under normal circumstances, when the relay is energized, the contact voltage difference is close to zero, and under abnormal circumstances, the contact voltage difference will be much greater than zero; at the same time, the state of the relay can be judged by receiving the voltage value of the relay coil relative to the ground through the DSP control unit. Under normal circumstances, when the relay is energized, the detected voltage value is close to zero, and under abnormal circumstances, the detected voltage value is close to the value of the power supply voltage VCC. The DSP control unit performs logical analysis and control on the above-mentioned sampling signal. When the result of the logical analysis is "the relay has a fault", the drive of the main power drive circuit is immediately turned off, thereby turning off the main power. In addition, the relay is reliably turned off under zero current or very small current conditions. The DSP performs logical analysis and control on the above-mentioned sampling signal. When the result of the logical analysis is "the relay is normal", the drive of the 8-way PWM drive signal continues to be maintained, and the main power drive circuit performs power transmission, and the transmitted current passes through the contacts of the relay to the load end.

[0048] It should be noted that, among the above three parts, Part_1 and Part_2 detect the relay contact voltage and coil voltage respectively. In actual use, only one of them can be detected to achieve the purpose of fault detection, but when both are detected at the same time, better results will be achieved.

[0049] Figure 1 Part_4 shown in the figure is a relay and its driving circuit, wherein the relay driving circuit includes a transistor Q1, the emitter of the transistor Q1 is grounded, the base is connected to the driving signal input terminal, the collector is connected to the input terminal of the relay, and the base inputs the relay driving signal Relay_Drive". Under normal circumstances, the "Relay_Drive" signal is at a high level, the relay contacts are energized, and current passes through the contact reed of the relay. Furthermore, a resistor R10 is also connected between the collector of the transistor Q1 and the input terminal of the relay. It should be noted that the relay driving circuit shown above is only a simple implementation method in this embodiment. The relay driving circuit provided by the present invention can also be other driving circuits, which are not limited here.

[0050] Figure 1Part_5 shown in the figure is the main power drive circuit, which is a DC-DC converter circuit. Under normal circumstances, the drive signals "PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8" from the central controller DSP drive the power switch tube of the DC / DC converter to achieve power conversion of the DC / DC converter. When "PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8" are all low levels, the DC-DC converter stops power transmission, and the current flowing into the relay contacts is very small or zero current.

[0051] It should be noted that the application of the relay anti-arcing circuit in this embodiment to the DC / DC converter circuit is only one implementation method. The relay anti-arcing circuit can also be applied to AC-DC converter circuits and other systems using relays.

[0052] Example 2

[0053] The second aspect of the present invention provides a control method, which is applied to the above-mentioned relay anti-arc circuit, the relay anti-arc circuit includes a relay, a relay drive circuit connected to the relay, a voltage detection circuit, a central controller and a main power drive circuit. The specific circuit structure can be seen in the description of embodiment 1, which will not be repeated here. The control method is as follows Figure 2 As shown, including:

[0054] Step S10: The voltage detection circuit detects the voltage signal of the relay and transmits the voltage signal to the central controller.

[0055] The voltage signal can be detected by the above-mentioned resistance voltage division detection method, whose circuit topology has been specifically described in Example 1, or other detection methods such as operational amplifier circuits or external hardware comparison circuits can be used. On the basis of determining the circuit detection method, a relay contact voltage detection circuit and a relay coil voltage detection circuit can be further set to respectively collect the contact voltage signal and the coil voltage signal, and transmit the contact voltage signal and the coil voltage signal to the central controller.

[0056] It should be noted that only one of the contact voltage signal and the coil voltage signal needs to be transmitted to the central controller, or both of them need to be transmitted to the central controller to obtain a better control effect.

[0057] Step S20: The central controller performs logic analysis and control on the voltage signal, and outputs a control signal according to the logic analysis result.

[0058] The step further comprises:

[0059] The central controller calculates the voltage value according to the voltage signal and compares the voltage value with the voltage threshold. Based on step S10, the central controller may obtain the voltage signal of the relay contact, calculate the voltage value of the relay contact according to the voltage signal, and compare the voltage value with the voltage threshold; and / or, the central controller obtains the voltage signal of the relay coil, calculates the voltage value of the relay coil according to the coil voltage signal, and compares the voltage value with the voltage threshold.

[0060] When the compared voltage value is greater than the voltage threshold, the voltage value duration continues to be compared with the time threshold; and when the duration is greater than the time threshold, it is determined that the relay fails, and then a control signal is output.

[0061] Step S30: The main power driving circuit turns off or maintains the current input to the relay according to the control signal, so that the contact spring of the relay is separated under the condition of zero current or small current.

[0062] like Figure 3 The detailed flow chart shown in the figure includes sampling of the relay contact voltage and sampling of the relay coil voltage. Specifically, it includes: Scheme 1, sampling the relay contact voltage, and calculating the voltage value of the relay contact. When the contact voltage is greater than the voltage threshold V1, continue to judge the duration. When the duration is greater than the time threshold T1, it is judged that the relay is faulty, and the fault signal is sent to the central controller, and the central controller shuts down the main power converter; Scheme 2, sampling the relay coil voltage, and calculating the voltage value of the relay coil. When the contact voltage is greater than the voltage threshold V2, continue to judge the duration. When the duration is greater than the time threshold T2, it is judged that the relay is faulty, and the fault signal is sent to the central controller, and the central controller shuts down the main power converter; the above schemes 1 and 2 can be carried out simultaneously, such as Figure 4 -5 respectively provide the relay contact voltage timing diagram and the relay coil voltage timing diagram.

[0063] In summary, the applicant believes that the relay anti-arcing circuit and control method provided by the present invention have a simple circuit structure, occupy a small space, and can realize the disengagement of the contact spring of the relay under zero current or low current conditions. It is a low-cost anti-arcing solution.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A relay anti-arc circuit, characterized in that: include: A relay, a relay drive circuit connected to the relay, a voltage detection circuit, a central controller and a main power drive circuit; wherein, The voltage detection circuit is used to detect the voltage signal of the relay and transmit the voltage signal to the central controller; wherein the voltage signal includes a relay contact voltage signal and / or a relay coil voltage signal; The central controller is used to perform logic analysis and control on the voltage signal, and output a control signal according to the logic analysis result; wherein, when the voltage signal is the relay contact voltage signal, if the voltage difference between the voltage of the first contact of the relay and the voltage of the second contact of the relay is within a preset first threshold range, the logic analysis result is determined to be that the relay is normal, and if the voltage difference is within a preset second threshold range, the logic analysis result is determined to be that the relay is abnormal; when the voltage signal is the relay coil voltage signal, if the voltage value of the relay coil is within the first threshold range, the logic analysis result is determined to be that the relay is normal, and if the voltage value of the relay coil is within a preset third threshold range, the logic analysis result is determined to be that the relay is abnormal, the minimum value of the first threshold range is 0, and the minimum values ​​of the second threshold range and the third threshold range are both greater than the maximum value of the first threshold range; The main power driving circuit is used to shut down or maintain the current input to the relay according to the control signal; wherein, when the control signal corresponds to the logic analysis result of the abnormality of the relay, the current input to the relay is shut down.

2. The relay anti-arc circuit according to claim 1, characterized in that: The input end of the voltage detection circuit is connected between the relay and the relay driving circuit.

3. The relay anti-arc circuit according to claim 1, characterized in that: The input end of the voltage detection circuit is connected to the contact of the relay.

4. The relay anti-arc circuit according to claim 3, characterized in that: The contact points include two, the voltage detection circuit includes a first voltage detection circuit and a second voltage detection circuit, the input end of the first voltage detection circuit is connected to one of the contact points, and the input end of the second voltage detection circuit is connected to the other contact point.

5. The relay anti-arc circuit according to claim 2 or 3, characterized in that: The voltage detection circuit includes a voltage-dividing resistor and a filter circuit. One end of the voltage-dividing resistor is the input end of the voltage signal, and the other end of the voltage-dividing resistor is connected to the central controller via the filter circuit.

6. The relay anti-arc circuit according to claim 5, characterized in that: The voltage detection circuit is an operational amplifier circuit or an external hardware comparison circuit.

7. The relay anti-arc circuit according to claim 6, characterized in that: The central controller is a DSP control unit, the DSP control unit is provided with at least one voltage sampling AD port or IO port, and the DSP control unit is provided with a PWM drive signal output interface.

8. The relay anti-arc circuit according to claim 7, characterized in that: The main circuit controlled by the main power driving circuit is one of a DC-DC converter circuit and an AC-DC converter circuit.

9. A control method, characterized in that: Applied to a relay anti-arcing circuit, the relay anti-arcing circuit includes a relay, a relay drive circuit connected to the relay, a voltage detection circuit, a central controller and a main power drive circuit, and the control method includes: The voltage detection circuit detects the voltage signal of the relay and transmits the voltage signal to the central controller; wherein the voltage signal includes a relay contact voltage signal and / or a relay coil voltage signal; The central controller performs logic analysis and control on the voltage signal, and outputs a control signal according to the logic analysis result; wherein, when the voltage signal is the relay contact voltage signal, if the voltage difference between the voltage of the first contact of the relay and the voltage of the second contact of the relay is within a preset first threshold range, the logic analysis result is determined to be that the relay is normal, and if the voltage difference is within a preset second threshold range, the logic analysis result is determined to be that the relay is abnormal; when the voltage signal is the relay coil voltage signal, if the voltage value of the relay coil is within the first threshold range, the logic analysis result is determined to be that the relay is normal, and if the voltage value of the relay coil is within a preset third threshold range, the logic analysis result is determined to be that the relay is abnormal, and the maximum value of the first threshold range is less than the minimum value of the second threshold range and the minimum value of the third threshold range; The main power driving circuit turns off or maintains the current input to the relay according to the control signal; wherein, when the control signal corresponds to the logic analysis result of the abnormality of the relay, the current input to the relay is turned off.

10. The control method according to claim 9, characterized in that: The central controller performs logic analysis and control on the voltage signal, and outputs a control signal according to the logic analysis result, and further includes: The central controller calculates a voltage value according to the voltage signal and compares the voltage value with a voltage threshold; When the voltage value is greater than the voltage threshold, continue to compare the voltage value duration with the time threshold; When the duration is greater than the time threshold, it is determined that the relay fails and a control signal is output.

11. The control method according to claim 10, characterized in that: The central controller calculates the voltage value according to the voltage signal and compares the voltage value with the voltage threshold, including: The central controller acquires a voltage signal of a relay contact, calculates a voltage value of the relay contact according to the voltage signal, and compares the voltage value with the voltage threshold; And / or, the central controller acquires a voltage signal of the relay coil, calculates a voltage value of the relay coil according to the voltage signal, and compares the voltage value with the voltage threshold.

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