Direct-current electromagnetic valve driving circuit

Abstract

The utility model discloses a direct-current electromagnetic valve driving circuit which comprises a direct-current electromagnetic valve soft starting loop and a direct-current electromagnetic valve driving loop. The soft start loop of the direct-current electromagnetic valve comprises a start resistor; the first field effect transistor is connected with the starting resistor in parallel; the control circuit controls the gate voltage of the first field effect transistor; the direct-current electromagnetic valve has the beneficial effects that when the direct-current electromagnetic valve is electrified and started, the impact on an input power supply during starting work is effectively reduced, and the electromagnetic compatibility is improved.

Description

Technical Field

[0001] The present application relates to the field of solenoid valves, and in particular to a direct current solenoid valve drive circuit. Background Art

[0002] DC solenoid valves are widely used in electronic and electrical applications. Since DC solenoid valves are inductive devices, improper use in circuits will easily cause damage to the drive circuit or interfere with peripheral circuits.

[0003] At present, the common design is to connect a freewheeling diode in parallel at both ends of the coil of the DC solenoid valve to suppress the reverse peak electromotive force and protect the solenoid valve coil. Simply connecting a freewheeling diode in parallel to suppress the reverse peak electromotive force can easily damage the freewheeling diode; and more complete drive circuit protection and fault detection functions for DC solenoid valves are relatively lacking or too simple, resulting in limited protection performance. Utility Model Content

[0004] The utility model provides a DC solenoid valve driving circuit to solve one of the problems raised in the above background technology:

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A DC solenoid valve driving circuit comprises: a DC solenoid valve soft start circuit;

[0007] The DC solenoid valve soft start circuit includes: a starting resistor;

[0008] A first field effect transistor, wherein the first field effect transistor is connected in parallel with a starting resistor;

[0009] A control circuit controls the gate voltage of the first field effect transistor.

[0010] Further: the starting resistor is connected in series with one end of the self-recovery fuse;

[0011] The other end of the self-recovery fuse is connected in series with the cathode of the first diode;

[0012] Among them, the unidirectional conduction characteristic of the diode is utilized to prevent the phenomenon of damaging the device due to reverse connection of the working power supply. Also, due to the characteristics of the resistance of the self-recovery fuse, the resistance of the self-recovery fuse resistor increases sharply, limiting the circuit current until the circuit current is zero and the DC solenoid valve is powered off, thereby protecting the working power supply.

[0013] Further: the control circuit includes: a charging capacitor;

[0014] A fifth resistor; one end of the fifth resistor is connected in series with one end of the charging capacitor;

[0015] a first optical coupler, wherein an emitter of a light detector of the first optical coupler is connected in series with the other end of the fifth resistor;

[0016] The collector of the photodetector of the first optical coupler is connected in parallel with the drain of the first field effect transistor;

[0017] A fourth resistor, one end of the fourth resistor is connected in series with the other end of the charging capacitor;

[0018] The other end of the fourth resistor is connected in series with the gate of the first field effect transistor;

[0019] When the voltage on the charging capacitor reaches the turn-on voltage of the first field effect transistor, the soft start ends, thereby determining the soft start time.

[0020] Further: it also includes a current loop controlled by a DS driving signal, and the current loop controlled by the DS driving signal includes an eighth resistor;

[0021] a second field effect transistor, wherein a gate of the second field effect transistor is connected in series with one end of an eighth resistor;

[0022] a third diode, wherein the cathode of the third diode is connected in series with the drain of the second field effect transistor;

[0023] A first optical coupler, wherein the cathode of an LED of the first optical coupler is connected in series with the anode of a third diode;

[0024] A first voltage stabilizing diode, wherein the anode of the first voltage stabilizing diode is connected in series to the LED anode of the first optical coupler;

[0025] a third resistor, one end of the third resistor being connected in series to the cathode of the first voltage zener diode, and the other end of the third resistor being connected to the positive end of the DC solenoid valve;

[0026] A third voltage stabilizing diode, wherein the third voltage stabilizing diode is connected in series with an eighth resistor;

[0027] A current sampling resistor, one end of which is connected in series to the source of the second field effect transistor;

[0028] A clamping diode, wherein the clamping diode is connected in series with the other end of the current sampling resistor;

[0029] Among them, the driving signal provides a gate operating voltage for the second field effect tube through the eighth resistor, and the eighth resistor is connected in series with the third voltage regulator diode. The third voltage regulator diode limits the voltage amplitude of the driving signal, thereby protecting the second field effect tube from being damaged due to excessive gate voltage.

[0030] Further: it also includes a DC solenoid valve power-off quick release circuit, and the DC solenoid valve power-off quick release circuit includes a freewheeling diode;

[0031] A release resistor, wherein the release resistor is connected in parallel with the freewheeling diode;

[0032] The release resistor and the freewheeling diode are both connected in parallel with the DC solenoid valve;

[0033] Among them, when the DC solenoid valve is powered off, a current loop is formed through the freewheeling diode and the release resistor, providing a quick release channel for the reverse peak electromotive force.

[0034] It also includes a DC solenoid valve fault detection and output function circuit, and the DC solenoid valve fault detection and output function circuit includes a current sampling resistor;

[0035] A clamping diode, wherein the clamping diode is connected in series with the other end of the current sampling resistor;

[0036] A positive phase amplifier, wherein the inverting input terminal of the positive phase amplifier is connected to the cathode of the clamping diode, and the positive phase input terminal of the positive phase amplifier is connected to one end of the current sampling resistor through a tenth resistor;

[0037] A first triode, wherein a base of the first triode receives an output voltage of the positive-phase amplifier;

[0038] A second photoelectric coupler, wherein the cathode of an LED of the second photoelectric coupler is connected to the collector of the first transistor;

[0039] A first relay coil is connected to a collector of a photodetector of a second photocoupler.

[0040] The beneficial effects of this application are:

[0041] 1: Design a DC solenoid valve soft start circuit. When the DC solenoid valve is powered on and started, it can effectively reduce the impact on the input power during startup and improve electromagnetic compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to facilitate understanding by those skilled in the art, the present invention is further described below in conjunction with the accompanying drawings.

[0043] Figure 1 This is a circuit structure block diagram of this application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model 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 utility model and are not used to limit the utility model, that is, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the utility model provided in the accompanying drawings is not intended to limit the scope of the utility model claimed for protection, but merely represents selected embodiments of the utility model. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0046] The present invention is limited only by the claims and their full scope and equivalents. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be an installed 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, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] See also Figure 1 In an embodiment of the present application, a DC solenoid valve driving circuit includes: a DC solenoid valve soft start circuit; the DC solenoid valve soft start circuit includes: a start resistor R1; a first field effect transistor Q1, the first field effect transistor Q1 is connected in parallel with the start resistor R1; a control circuit, the control circuit controls the gate voltage of the first field effect transistor Q1;

[0049] Specifically: the first diode D1, the resistor F1 of the self-recovery insurance, the starting resistor R1, the DC solenoid valve, the first field effect transistor Q1, the drain of the second field effect transistor Q2, the source of the second field effect transistor Q2, the current sampling resistor R13, the clamping diode D6 and the voltage output terminal DC- are electrically connected to form a current loop for the DC solenoid valve to work;

[0050] The second field effect transistor Q2, the resistor R3, the current limiting resistor R8, the positive terminal of the DC solenoid valve, the first voltage stabilizing diode DZ1, the third voltage stabilizing diode DZ3, the first photocoupler U1, the third diode D3, the current sampling resistor R13, the fourth field effect transistor Q4, the clamping diode D6 and GND are electrically connected to form a current loop controlled by the DS drive signal;

[0051] The current loop of the DC solenoid valve and the current loop controlled by the DS drive signal constitute a DC solenoid valve soft start loop, wherein: the positive end of the first diode D1 is connected to the power supply, and the unidirectional conduction characteristic of the diode is used to prevent the phenomenon of reverse connection of the working power supply and damage to the device; the starting resistor R1 and the first field effect transistor Q1 are connected in parallel to achieve full working voltage switching after soft start; the current limiting resistor R8 and the third voltage zener diode DZ3 are connected in series to limit the voltage amplitude of the external input drive signal, thereby protecting the second field effect transistor Q2 from being damaged by excessive gate voltage; one end of the third resistor R3 is connected to the positive end of the DC solenoid valve to obtain the DC solenoid valve voltage in real time; the other end of the third resistor R3 is connected to the negative end of the first voltage zener diode DZ1 to limit the voltage.

[0052] The first diode D1, the self-recovery fuse resistor F1, the current sampling resistor R13, the fourth field effect transistor Q4 and the clamping diode D6 constitute a DC solenoid valve short-circuit overcurrent protection circuit; the negative end of the first diode D1 is connected to one end of the self-recovery fuse resistor F1, the other end of the self-recovery fuse resistor F1 is connected to one end of the starting resistor R1, the other end of the starting resistor R1 is connected to the positive end of the DC solenoid valve, and the negative end of the DC solenoid valve is connected to the current loop controlled by the DS drive signal, thus forming a DC solenoid valve short-circuit overcurrent protection circuit as a whole.

[0053] The DC solenoid valve power-off quick release circuit includes a freewheeling diode D2, a release resistor R2 and a DC solenoid valve; the freewheeling diode D2, the release resistor R2 and the DC solenoid valve are all connected in parallel; the release resistor R2 provides a shunt effect and a quick release of a high-voltage spike pulse for the freewheeling diode D2.

[0054] The DC solenoid valve fault detection and output function circuit includes a positive phase amplifier circuit composed of a current sampling resistor R13, a clamping diode D6, a tenth resistor R10, a fourteenth resistor R14, a fifteenth resistor R15, a second photocoupler U2, a relay RELAY1 and a positive phase amplifier U3A; the fourteenth resistor R14 is connected in parallel with the inverting input terminal of the positive phase amplifier U3A in the positive phase amplifier circuit; the fifteenth resistor R15 is connected in series with the inverting input terminal of the positive phase amplifier U3A in the positive phase amplifier circuit; the fourteenth resistor R14 and the fifteenth resistor R15 determine the amplification factor of the positive phase amplifier circuit.

[0055] The working principle of this application is as follows:

[0056] DC solenoid valve soft start:

[0057] During the soft start process: DC+ passes through the first diode D1, the self-recovery fuse resistor F1, the starting resistor R1, the DC solenoid valve +, the DC solenoid valve -, the drain of the second field effect transistor Q2, the source of the second field effect transistor Q2, the current sampling resistor R13, and the clamping diode D6 to DC-, forming a current loop for the DC solenoid valve to work; the conduction of the second field effect transistor Q2 is controlled by the gate voltage of the second field effect transistor Q2. Only when there is a suitable gate voltage, the second field effect transistor Q2 can be turned on, and the drain current will flow into the source, thereby providing a current path for the DC solenoid valve; the drive signal DS is provided by the peripheral device, and after being limited by the current limiting resistor R8 and the third voltage stabilizing diode DZ3, it provides a safe and reliable gate control voltage for the second field effect transistor Q2; and the DC solenoid valve is an inductor device. According to the inductance characteristics, the working current of the DC solenoid valve is large at the moment of power-on, but due to the existence of the starting resistor R1, it plays a current limiting role, avoiding the large current impact on the input power supply due to the start of the DC solenoid valve;

[0058] Soft start ends: under the action of the DS drive signal, the drain and source of the second field effect tube Q2 are turned on; one end of the third resistor R3 is connected to the + end of the DC solenoid valve to obtain the DC solenoid valve voltage in real time; the other end of the third resistor R3 is connected to the negative end of the first voltage regulator diode to limit the voltage; the positive end of the first voltage regulator diode DZ1 is connected to the LED anode of the first photocoupler U1, and the LED cathode of the first photocoupler U1 is connected to the drain and source of the second field effect tube Q2 through the third diode D3, and the current sampling resistor R13 and the clamping diode D6 are connected to GND to form a current loop. The first photocoupler U1 has current flowing through the 1 and LED cathodes, so that the collector and emitter of the photodetector of the first photocoupler U1 are turned on; the working power supply DC+ passes through the collector and emitter of the photodetector of the first photocoupler U1, the fifth resistor R5, the charging capacitor C1, and the fourth resistor R4, and provides the gate working voltage to the first field effect tube Q1, the drain and source of the first field effect tube Q1 are turned on, and the starting resistor is short-circuited by the drain and source of the first field effect tube Q1; at this time, the starting resistor R1 fails, and the working current of the DC solenoid valve is not limited by the starting resistor R1. The soft start time is determined by the charging time of the charging capacitor C1. When the voltage on the charging capacitor C1 reaches the turn-on voltage of the first field effect tube Q1, the soft start ends.

[0059] The short circuit overcurrent protection of DC solenoid valve is completed in two ways:

[0060] 1. Protection by self-recovery insurance: When the resistor F1 of the self-recovery insurance is in the state of short circuit or overcurrent, the self-recovery insurance characteristic generates heat and the resistance of the self-recovery insurance resistor F1 increases sharply, limiting the circuit current until the circuit current is zero and the DC solenoid valve is powered off, thus protecting the working power supply;

[0061] 2. The current sampling resistor R13 provides protection: The current sampling resistor R13 detects the loop current in real time in the DC solenoid valve power-on loop. When the loop current changes abnormally, the voltage on the current sampling resistor R13 is sufficient to drive the fourth field effect transistor Q4 to turn on. When the drain and source of the fourth field effect transistor Q4 are turned on, the DS drive signal passes through the drain, source, and clamping diode D6 of the fourth field effect transistor Q4, and the gate voltage of the second field effect transistor Q2 is clamped at 0.7V. The 0.7V voltage cannot turn on the second field effect transistor Q2 to work; when the second field effect transistor Q2 is disconnected, the working current of the DC solenoid valve cannot form a loop, and the DC solenoid valve is powered off and stops working.

[0062] DC solenoid valve power off quick release:

[0063] When the DC solenoid valve is powered off, it will generate a high reverse peak electromotive force, which is very harmful to the circuit and the DC solenoid valve; the freewheeling diode D2 and the release resistor R2 are connected in parallel with the DC solenoid valve, and the release resistor R2 provides a shunt effect and quickly releases high-voltage spike pulses for the freewheeling diode D2. The positive pole of the freewheeling diode D2 is connected to the DC solenoid valve - phase, and the negative pole of the freewheeling diode D2 is connected to the DC solenoid valve + phase; when the DC solenoid valve is powered off, a current path is formed through the freewheeling diode D2 and the release resistor R2, providing a quick release channel for the reverse peak electromotive force.

[0064] DC solenoid valve fault detection and output functions:

[0065] When a short circuit or overcurrent occurs in the DC solenoid valve, the voltage of the current sampling resistor R13 and the clamping diode D6 is loaded to the positive input terminal of the positive amplifier U3A through the tenth resistor R10. The positive amplifier U3A constitutes a positive amplifier circuit, and the circuit amplification factor is determined by the fourteenth resistor and R15; the positive amplifier U3A outputs the amplified current sampling voltage, which is connected to the base of the first transistor Q3 through the current limiting resistor R12; the VCC power supply supplies power to the collector of the first transistor Q3 through the resistor R7 and the LED of the second photocoupler U2; the base current of the first transistor Q3 makes the collector and emitter of the first transistor Q3 saturated and turned on; the LED of the second photocoupler U2 works, and the collector and emitter of the photodetector are turned on; VCC forms a current loop through the relay RELAY1 coil and the collector and emitter of the second photocoupler U2 photodetector, the relay RELAY1 is energized and works, the relay RELAY1 contacts are actuated, and an alarm signal is output. The above contents are merely examples and explanations of the structure of the utility model. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the utility model or exceed the scope defined in the claims, they should all fall within the protection scope of the utility model.

Claims

1. A DC solenoid valve drive circuit, characterized in that: include: DC solenoid valve soft start circuit; The DC solenoid valve soft start circuit includes: a starting resistor; A first field effect transistor, wherein the first field effect transistor is connected in parallel with a starting resistor; A control circuit controls the gate voltage of the first field effect transistor.

2. A DC solenoid valve drive circuit according to claim 1, characterized in that: The starting resistor is connected in series with one end of the self-recovery fuse; The other end of the self-recovery fuse is connected in series to the cathode of the first diode.

3. A DC solenoid valve drive circuit according to claim 1, characterized in that: The control circuit comprises: a charging capacitor; A fifth resistor; one end of the fifth resistor is connected in series with one end of the charging capacitor; a first optical coupler, wherein an emitter of a light detector of the first optical coupler is connected in series with the other end of the fifth resistor; The collector of the photodetector of the first optical coupler is connected in parallel with the drain of the first field effect transistor; A fourth resistor, one end of the fourth resistor is connected in series with the other end of the charging capacitor; The other end of the fourth resistor is connected in series with the gate of the first field effect transistor.

4. A DC solenoid valve drive circuit according to claim 1, characterized in that: Also includes a current loop controlled by a DS driving signal, wherein the current loop controlled by the DS driving signal includes an eighth resistor; a second field effect transistor, wherein a gate of the second field effect transistor is connected in series with one end of an eighth resistor; a third diode, wherein the cathode of the third diode is connected in series with the drain of the second field effect transistor; A first optical coupler, wherein the cathode of an LED of the first optical coupler is connected in series with the anode of a third diode; A first voltage stabilizing diode, wherein the anode of the first voltage stabilizing diode is connected in series to the LED anode of the first optical coupler; a third resistor, one end of the third resistor being connected in series to the cathode of the first voltage zener diode, and the other end of the third resistor being connected to the positive end of the DC solenoid valve; A third voltage stabilizing diode, wherein the third voltage stabilizing diode is connected in series with an eighth resistor; A current sampling resistor, one end of which is connected in series to the source of the second field effect transistor; A clamping diode is connected in series with the other end of the current sampling resistor.

5. A DC solenoid valve drive circuit according to claim 1, characterized in that: It also includes a DC solenoid valve power-off quick release circuit, and the DC solenoid valve power-off quick release circuit includes a freewheeling diode; A release resistor, wherein the release resistor is connected in parallel with the freewheeling diode; The release resistor and the freewheeling diode are both connected in parallel with the DC solenoid valve.

6. A DC solenoid valve drive circuit according to claim 1, characterized in that: It also includes a DC solenoid valve fault detection and output function circuit, and the DC solenoid valve fault detection and output function circuit includes a current sampling resistor; A clamping diode, wherein the clamping diode is connected in series with the other end of the current sampling resistor; A positive phase amplifier, wherein the inverting input terminal of the positive phase amplifier is connected to the cathode of the clamping diode, and the positive phase input terminal of the positive phase amplifier is connected to one end of the current sampling resistor through a tenth resistor; A first triode, wherein a base of the first triode receives an output voltage of the positive-phase amplifier; A second photoelectric coupler, wherein the cathode of an LED of the second photoelectric coupler is connected to the collector of the first transistor; A first relay coil is connected to a collector of a photodetector of a second photocoupler.

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