Electromagnetic valve turn-off discharge circuit

Abstract

The invention discloses an electromagnetic valve turn-off discharge circuit, and relates to the technical field of circuit control. The circuit comprises a driving module DRV, an electromagnetic valve coil L0 and an electromagnetic valve switch M0, and further comprises a current mirror module, a one-way conduction module, a clamping module and a driving resistor module. The current mirror module is used for providing a discharge condition when the electromagnetic valve coil L0 generates reverse electromotive force; the one-way conduction module is used for providing turn-on voltage for the electromagnetic valve switch M0 when the reverse electromotive force is generated, so that the electromagnetic valve switch M0 is conducted again and the reverse electromotive force is quickly released; the clamping module is used for limiting the control end voltage of the electromagnetic valve switch M0; and the driving resistor module adjusts the voltage of the node A according to an output signal of the driving module DRV so as to control the on-off of the electromagnetic valve switch M0. According to the scheme, through cooperation of all the modules, energy release of reverse electromotive force is effectively controlled, damage to circuit elements caused by overhigh voltage is prevented, and the performance of the electromagnetic valve is optimized under the condition that extra complexity is not increased.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit control, and more particularly to a solenoid valve turn-off discharge circuit. Background Art

[0002] A solenoid valve is a valve that controls the flow of fluid using electromagnetic force and is widely used in industrial automation and civilian systems. It drives the valve core through an electromagnetic coil to achieve the on-off control of the fluid. Due to the characteristics of fast response, remote control, high reliability, and multi-purpose, the solenoid valve has become a core component in the field of fluid control and plays an important role in scenarios such as the flow rate, flow direction, and pressure regulation of liquids and gases.

[0003] In practical applications, when the solenoid valve is turned off, a reverse voltage, i.e., a back electromotive force, will be generated in its coil due to the electromagnetic induction effect. This back electromotive force may damage the drive circuit and related components. In the prior art, to suppress the influence of the back electromotive force, a reverse freewheeling diode is usually connected in parallel across the solenoid valve coil. The freewheeling diode releases the back electromotive force by providing a low-impedance path, thereby effectively protecting the safety of the circuit. However, this freewheeling protection method changes the original characteristics of the circuit, resulting in a certain delay when the solenoid valve operates, which has an adverse impact on the system performance. In addition, in high-frequency operation or high-current scenarios, the back electromotive force may also cause power supply voltage fluctuations through the power supply circuit, affecting the overall stability of the system.

[0004] Therefore, how to quickly release the back electromotive force of the solenoid valve while ensuring circuit safety and component protection, thereby reducing the operation delay and minimizing power supply fluctuations, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a solenoid valve turn-off discharge circuit that can adaptively discharge at the moment when the solenoid valve is turned off, effectively control the energy release of the back electromotive force, and significantly improve the response speed, especially under high-frequency or high-current conditions, enhancing the stability and working efficiency of the system.

[0006] To achieve the above purpose, the present invention discloses the following technical solutions: On the one hand, the present invention provides a solenoid valve turn-off discharge circuit, including a drive module DRV, a solenoid valve coil L0, and a solenoid valve switch M0, and further including: A current mirror module is used to provide a discharge condition when a back electromotive force is generated in the solenoid valve coil L0. The current mirror module includes a first current branch and a second current branch; one end of the first current branch is connected to one end of the solenoid valve coil L0 and is connected to the power supply voltage VCC, and the other end of the first current branch is grounded; one end of the second current branch is connected to the other end of the solenoid valve coil L0 through node B, and the other end of the second current branch is connected to the positive end of the unidirectional conduction module; A unidirectional conduction module, whose negative end is connected to the control end of the solenoid valve switch M0. When the solenoid valve switch M0 is turned off and a back electromotive force is generated in the solenoid valve coil L0, the back electromotive force provides an opening voltage for the control end of the solenoid valve switch M0 through the second current branch and the unidirectional conduction module, so that the solenoid valve switch M0 is re-conducted and the back electromotive force is quickly discharged; A clamping module, one end of which is connected to node A between the unidirectional conduction module and the control end of the solenoid valve switch M0, and the other end is grounded, and is used to limit the voltage generated by the back electromotive force at the control end of the solenoid valve switch M0; A driving resistance module, one end of which is connected to node A and the other end is connected to the output end of the driving module DRV, and is used to adjust the voltage of node A according to the output signal of the driving module DRV to control the opening and closing of the solenoid valve switch M0.

[0007] Optionally, in the above solenoid valve turn-off discharge circuit, when the input signal S_CTRL of the driving module DRV is at a high level, the driving module DRV outputs an opening driving signal, and the driving resistance module raises the voltage of node A, so that the solenoid valve switch M0 is turned on and the voltage of node B decreases; at this time, due to the limitation of the unidirectional conduction module, current will not flow from node A to node B, and the power supply voltage VCC charges the solenoid valve coil L0, and the charging current of the solenoid valve coil L0 gradually increases with time until the state of the solenoid valve changes and reaches a stable state; When the input signal S_CTRL of the driving module DRV changes from a high level to a low level, the driving module DRV outputs a turn-off driving signal, and the driving resistance module pulls down the voltage of node A, so that the solenoid valve switch M0 is turned off; at this time, the back electromotive force generated by the solenoid valve coil L0 charges the parasitic capacitance of the solenoid valve switch M0 to increase the voltage of node B, the second current branch starts to conduct and the voltage of node A gradually increases. When the voltage of node A increases to re-turn on the solenoid valve switch M0, the back electromotive force generated by the solenoid valve coil L0 is quickly discharged through the solenoid valve switch M0 until the solenoid valve returns to its initial state.

[0008] Optionally, in the above solenoid valve turn-off discharge circuit, the first current branch includes a first switching transistor M1 and a constant current source I0, and the second current branch includes a second switching transistor M2; the power supply voltage VCC is grounded through the first switching transistor M1 and the constant current source I0 in sequence; the control terminal of the first switching transistor M1 is connected to the control terminal of the second switching transistor M2 and is connected to the input terminal of the constant current source I0, so as to provide a bias voltage for the second switching transistor M2 through the constant current source I0.

[0009] Optionally, in the above solenoid valve turn-off discharge circuit, both the first switching transistor M1 and the second switching transistor M2 are PMOS transistors. The source of the first switching transistor M1 is connected to one end of the solenoid valve coil L0, and the drain is connected to the constant current source I0; the source of the second switching transistor M2 is connected to the other end of the solenoid valve coil L0, and the drain is connected to one end of the unidirectional conduction module.

[0010] Optionally, in the above solenoid valve turn-off discharge circuit, the unidirectional conduction module includes a rectifier diode D1. The anode of the rectifier diode D1 is connected to the drain of the second switching transistor M2, and the cathode is connected to the control terminal of the solenoid valve switch M0.

[0011] Optionally, in the above solenoid valve turn-off discharge circuit, the clamping module includes a zener diode D0. The cathode of the zener diode D0 is connected to node A, and the anode is grounded, for limiting the voltage generated at node A by the back electromotive force of the solenoid valve coil L0.

[0012] Optionally, in the above solenoid valve turn-off discharge circuit, the drive resistance module includes an initialization resistor R0 and a bias resistor R1; wherein, one end of the initialization resistor R0 is grounded, and the other end is connected to one end of the bias resistor R1 and is connected to the output terminal of the drive module DRV, for making the voltage at the control terminal of the solenoid valve switch M0 always be low level before the circuit starts; the other end of the bias resistor R1 is connected to the control terminal of the solenoid valve switch M0, for transmitting the voltage at the control terminal of the solenoid valve switch M0 and providing a bias voltage for the control terminal of the solenoid valve switch M0 when discharging the back electromotive force.

[0013] Optionally, for the above solenoid valve turn-off discharge circuit, the current value of the constant current source I0 is set as: ; wherein, I0 is the current value of the constant current source, N1 / N2 is the ratio of the width-to-length ratio of the second switching transistor M2 to the first switching transistor M1, R1 is the resistance value of the bias resistor, and V TH_M0 is the conduction threshold voltage of the solenoid valve switch M0.

[0014] Optionally, in the above solenoid valve turn-off discharge circuit, when the input signal S_CTRL of the driving module DRV is continuously low, after the back electromotive force is discharged completely, the driving module DRV outputs a turn-off driving signal, which pulls down the voltage of node A after passing through the driving resistor module, and the solenoid valve switch M0 is turned off; at this time, the voltage of node B is equal to the power supply voltage VCC, and the current IL in the solenoid valve coil L0 is 0A; When the input signal S_CTRL of the driving module DRV is high, the driving module DRV outputs an on driving signal, which makes the voltage of node A rise to a high level after passing through the bias resistor R1, the solenoid valve switch M0 is turned on, and the voltage of node B is pulled down; at this time, due to the limitation of the unidirectional conduction module, the current will not flow from node A to node B, and the current IL in the solenoid valve coil L0 gradually rises with time until the current reaches a steady state; At the moment when the input signal S_CTRL of the driving module DRV changes from high level to low level, the driving module DRV outputs a turn-off driving signal, the voltage of node A drops rapidly, and the solenoid valve switch M0 is turned off; at this time, the back electromotive force generated by the solenoid valve coil L0 charges the parasitic capacitance of the solenoid valve switch M0 to raise the voltage of node B, the second current branch starts to conduct and the voltage of node A gradually rises. When the voltage of node A rises to turn on the solenoid valve switch M0 again, the back electromotive force generated by the solenoid valve coil L0 is quickly discharged through the solenoid valve switch M0 until the energy is completely discharged, the solenoid valve returns to its initial state, and the voltage of node B returns to the power supply voltage VCC again.

[0015] On the other hand, the present invention provides a solenoid valve control system, including the solenoid valve turn-off discharge circuit as described in the first aspect.

[0016] The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects: A solenoid valve cut-off discharge circuit provided by the present application realizes the adaptive discharge at the moment of solenoid valve cut-off through the cooperation of existing components and a current mirror module, a unidirectional conduction module, a clamping module, and a driving resistance module. Especially in the high-frequency or high-current working state, the response speed and stability are significantly improved. This solution provides the discharge condition of the back electromotive force through the current mirror module; the unidirectional conduction module provides the opening voltage for the solenoid valve switch M0 when the back electromotive force is generated; the clamping module limits the voltage generated by the back electromotive force at the control end of the solenoid valve switch M0; the driving resistance module adjusts the control end voltage of the solenoid valve switch M0 according to the output signal of the driving module DRV. Through the synergistic effect of each device module, this solution effectively controls the energy release of the back electromotive force, prevents damage to circuit components caused by excessive voltage, and at the same time ensures that the cut-off process of the solenoid valve is fast and stable, optimizing the performance of the solenoid valve without increasing additional complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0018] Figure 1 is a schematic diagram of a solenoid valve discharge circuit in the prior art; Figure 2 is a schematic structural diagram of a solenoid valve cut-off discharge circuit according to an embodiment of the present application; Figure 3 is a schematic circuit diagram of a solenoid valve cut-off discharge circuit according to an embodiment of the present application; Figure 4 is Figure 3 a schematic diagram of a signal waveform of the solenoid valve cut-off discharge circuit in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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 used to limit the present invention.

[0020] It should be noted that the references to "one embodiment", "embodiment", "exemplary embodiment", etc. in this specification mean that the described embodiment may include specific features, structures, or characteristics, but not every embodiment must include these specific features, structures, or characteristics. In addition, such expressions do not refer to the same embodiment. Further, when combining embodiments to describe specific features, structures, or characteristics, whether or not there is an explicit description, it has been shown that it is within the knowledge of those skilled in the art to combine such features, structures, or characteristics into other embodiments.

[0021] Figure 1 It is a schematic diagram of a solenoid valve discharge circuit in the prior art. Refer to Figure 1 As shown, the discharge circuit includes a solenoid valve coil L0, a reverse freewheeling diode D0, a solenoid valve switch control tube M0, a drive module DRV, and a bias resistor R0. When the control signal S_CTRL is at a high level (S_CTRL = 1), the drive module DRV outputs an enabling drive signal to turn on the switch control tube M0. At this time, current flows through the solenoid valve coil L0 to drive the valve core to act, and the state of the solenoid valve changes. When the control signal S_CTRL is at a low level (S_CTRL = 0), the drive module DRV outputs a disabling drive signal to turn off the switch control tube M0. At this time, the reverse electromotive force generated by the solenoid valve coil L0 is released through the freewheeling diode D0, the magnetic field of the coil disappears, and the solenoid valve core returns to its initial state.

[0022] Although Figure 1 the solenoid valve discharge circuit in

[0023] can effectively protect the circuit from damage by reverse electromotive force through measures such as the reverse freewheeling diode D0, this protection means will have a certain impact on the action speed of the solenoid valve and the stability of the power supply system. To solve this problem, the embodiment of the present application provides a solenoid valve turn-off discharge circuit, which can adaptively discharge at the moment when the solenoid valve is turned off, especially significantly improving the response speed under high-frequency or high-current conditions and enhancing the stability and working efficiency of the system. Figure 2 , Figure 2The figure shows a schematic diagram of the solenoid valve turn-off discharge circuit structure according to an embodiment of the present application. The circuit includes a drive module DRV, a solenoid valve coil L0, and a solenoid valve switch M0 in the prior art. In addition, it further includes a current mirror module 110, a one-way conduction module 120, a clamping module 130, and a drive resistor module 140. The current mirror module 110 includes a first current branch and a second current branch, and is used to provide a discharge condition when a back electromotive force is generated in the solenoid valve coil L0. The input end of the first current branch is connected to one end of the solenoid valve coil L0 and is connected to the power supply voltage VCC, and the other end is grounded; the input end of the second current branch is connected to the other end of the solenoid valve coil L0 through node B, and the output end is connected to the positive end of the one-way conduction module 120. The negative end of the one-way conduction module 120 is connected to the control end of the solenoid valve switch M0. When the solenoid valve switch M0 is turned off, when a back electromotive force is generated in the solenoid valve coil L0, the back electromotive force provides an opening voltage for the control end of the solenoid valve switch M0 through the second current branch and the one-way conduction module, so that the solenoid valve switch M0 is re-conducted and the back electromotive force is quickly discharged. One end of the clamping module 130 is connected to node A between the one-way conduction module 120 and the control end of the solenoid valve switch M0, and the other end is grounded, and is used to limit the voltage generated by the back electromotive force at the control end of the solenoid valve switch M0. One end of the drive resistor module 140 is connected to node A, and the other end is connected to the output end of the drive module DRV, and is used to adjust the voltage of node A according to the output signal of the drive module DRV to control the opening and closing of the solenoid valve switch M0.

[0024] In this circuit, when the input signal S_CTRL of the drive module DRV is at a high level, the drive module DRV outputs an opening drive signal, pulls up the voltage of node A through the drive resistor module 140, and makes the solenoid valve switch M0 conductive. At this time, due to the limitation of the one-way conduction module 120, the current will not flow from node A to node B, and the charging current in the solenoid valve coil L0 gradually rises with time until the state of the solenoid valve changes and reaches a stable state. When the input signal S_CTRL of the drive module DRV is at a low level, the drive module DRV outputs a turn-off drive signal, pulls down the level of node A through the drive resistor module 140, and makes the solenoid valve switch M0 turn off. At this time, a back electromotive force is generated in the solenoid valve coil L0, and the drive current charges the parasitic capacitance Cds of the solenoid valve switch M0, raising the voltage of node B; as the voltage of node B rises, the second current branch conducts, and the voltage of node A also gradually rises; when the voltage of node A rises to make the solenoid valve switch M0 conductive again, the back electromotive force generated by the solenoid valve coil L0 is discharged through the solenoid valve switch M0. During this process, the clamping module 130 limits the voltage of node A to prevent damage to circuit components due to excessive voltage until the energy of the solenoid valve coil L0 is completely released, the solenoid valve returns to its initial state, and the circuit enters a static state.

[0025] The circuit structure of this embodiment realizes the adaptive discharge at the moment of solenoid valve shut-off. Especially in the high-frequency or high-current operating state, it can significantly improve the response speed, enhance the stability and working efficiency of the system. Through the collaborative action of each device module, this circuit can effectively control the release of the back electromotive force energy, prevent excessive voltage from damaging circuit components, and at the same time ensure that the shut-off process of the solenoid valve is fast and stable, optimizing the performance of the solenoid valve without increasing additional complexity.

[0026] Reference Figure 3 , Figure 3 shows a schematic diagram of a solenoid valve shut-off discharge circuit according to an embodiment of the present application. In this embodiment, the first current branch of the current mirror module 110 includes a first switching transistor M1 and a constant current source I0, and the second current branch includes a second switching transistor M2. The power supply voltage VCC is grounded through the first switching transistor M1 and the constant current source I0 in sequence; the control terminal of the first switching transistor M1 is connected to the control terminal of the second switching transistor M2 and is connected to the input terminal of the constant current source I0 to provide a bias voltage through the constant current source I0 to control the on-state of the second switching transistor M2. Preferably, both the first switching transistor M1 and the second switching transistor M2 are PMOS transistors. Specifically, the source of the first switching transistor M1 is connected to one end of the solenoid valve coil L0, and the drain is connected to the constant current source I0; the source of the second switching transistor M2 is connected to the other end of the solenoid valve coil L0, and the drain is connected to one end of the unidirectional conduction module 120.

[0027] In some embodiments, the unidirectional conduction module 120 includes a rectifier diode D1. The anode of the rectifier diode D1 is connected to the drain of the second switching transistor M2, and the cathode is connected to the control terminal of the solenoid valve switch M0. The rectifier diode can limit the charging path from node A to node B, and when the solenoid valve switch M0 is turned off, guide the back electromotive force current generated by the solenoid valve coil L0 to the control terminal of the solenoid valve switch M0, so that the level of node A rises, thereby re-controlling the solenoid valve switch M0 to turn on.

[0028] In some embodiments, the clamping module 130 includes a zener diode D0. The cathode of the zener diode D0 is connected to node A, and the anode is grounded. The zener diode D0 can limit the voltage generated by the back electromotive force at node A when the second current branch is conducting, effectively protecting the circuit from overvoltage and ensuring the voltage stability during the solenoid valve shut-off process. In other embodiments, the clamping module 130 can also be other circuits with voltage stabilization functions, and specific limitations are not made.

[0029] In some embodiments, the drive resistance module 140 includes an initialization resistor R0 and a bias resistor R1. One end of the initialization resistor R0 is grounded, and the other end is connected to one end of the bias resistor R1 and connected to the output end of the drive module DRV, and is used to make the voltage at the control end of the solenoid valve switch M0 always be at a low level before the circuit is started. The other end of the bias resistor R1 is connected to the control end of the solenoid valve switch M0, and is used to transfer the voltage at the control end of the solenoid valve switch M0 and provide a bias voltage for the control end of the solenoid valve switch M0 when discharging the back electromotive force.

[0030] In some embodiments, preferably, the current value of the constant current source I0 is set to: ; In the formula, I0 is the current value of the constant current source, N1 / N2 is the ratio of the width-to-length ratio of the second switching transistor M2 to the first switching transistor M1, R1 is the resistance value of the bias resistor, and V TH_M0 is the conduction threshold voltage of the solenoid valve switch M0. Among them, under the condition of satisfying formula (1), the ratio of the width-to-length ratio of the second switching transistor M2 to the first switching transistor M1 can be freely set according to actual needs.

[0031] Figure 4 is Figure 3 a schematic diagram of a signal waveform of a solenoid valve turn-off discharge circuit. Combining Figure 3 and Figure 4 it can be known that the working process of this circuit is as follows: In the time period from 0 to t1, the input signal S_CTRL of the drive module DRV is a continuous low level (S_CTRL = 0), the back electromotive force discharge is completed, the drive module DRV outputs a turn-off drive signal, and after passing through the bias resistor R1, the voltage at node A is at a low level, and the solenoid valve switch M0 is turned off. After the solenoid valve switch M0 is turned off, the charging path of the solenoid valve coil L0 is cut off, and the power supply voltage VCC no longer charges the solenoid valve coil L0. At this time, the voltage at node B is equal to the power supply voltage VCC, and the current IL in the solenoid valve coil L0 is 0A.

[0032] During the time period from t1 to t2, the input signal S_CTRL of the drive module DRV is at a high level. The drive module DRV outputs an enabling drive signal. After passing through the bias resistor R1, the voltage at node A is at a high level, the solenoid valve switch M0 conducts, the voltage at node B is pulled down, and the power supply voltage VCC charges the solenoid valve coil L0. According to the current formula I = U×T / L, where I is the current, U is the voltage, and T is the time, the current IL in the solenoid valve coil L0 can be expressed as IL = VCC×t / L, where t is the conduction duration of the solenoid valve switch M0 and L is the inductance of the solenoid valve coil L0. It can be seen from this that the current IL in the solenoid valve coil L0 increases proportionally with the conduction duration of the solenoid valve switch M0. When the conduction duration of the solenoid valve switch M0 is greater than the saturation duration of the solenoid valve coil L0, the current IL will reach a steady state and no longer increase.

[0033] During the time period from t2 to t3, at the moment when the input signal S_CTRL of the drive module DRV changes from a high level to a low level, the drive module DTV outputs a turn-off drive signal, and the voltage at node A drops rapidly, turning off the solenoid valve switch M0. During this process, due to the sudden change in current, the solenoid valve coil L0 generates a back electromotive force, which charges the parasitic capacitance Cds of M0, causing the voltage at node B to rise and the second switching transistor M2 to conduct. The unidirectional conduction module 120 gradually raises the voltage at node A. The unidirectional conduction module 120 can be used to guide the current and limit the current flow direction. When the voltage at node A rises to turn on the solenoid valve switch M0 again, the back electromotive force generated by the solenoid valve coil L0 is quickly discharged through the solenoid valve switch M0 until the energy is completely discharged, and the solenoid valve returns to its initial state. At this time, the voltage at node B returns to the power supply voltage VCC again, and the solenoid valve completes a complete switching process.

[0034] In practical applications, the circuit structure of this embodiment is also applicable to circuits such as relays that require rapid discharge of coil inductance.

[0035] From the above analysis, it can be seen that the solenoid valve turn-off discharge circuit of the embodiment of the present application realizes efficient energy release at the moment of solenoid valve turn-off by integrating the current mirror module, the unidirectional conduction module, the clamping module, and the drive resistor module. Compared with the traditional design, this circuit omits the traditional freewheeling diode, has a more concise structure, can adaptively discharge without an additional control circuit, effectively reducing the design complexity and cost. Under high-frequency or high-current conditions, this circuit has a fast response ability, and by multiplexing the solenoid valve switch M0, it not only improves the energy discharge efficiency but also effectively protects the circuit components from the high-voltage impact of the back electromotive force. In addition, in the balanced state, the setting of the current mirror module does not interfere with the normal operation of the solenoid valve switch M0, ensuring the system stability.

[0036] It should be noted that the solenoid valve turn-off discharge circuit in the above embodiments is only a preferred circuit structure for achieving the purpose of the present invention. In some other embodiments, other circuit structures capable of achieving the same function may also be selected for each circuit module or device, and the present application is not limited thereto.

[0037] In addition, the embodiment of the present application also provides a solenoid valve control system, including the solenoid valve turn-off discharge circuit in the above embodiments, which is used to achieve the fast, safe, and adaptive release of the back electromotive force of the solenoid valve. For the circuit structure and working process not described in detail in the solenoid valve control system of this embodiment, reference may be made to the relevant parts in the above embodiments of the solenoid valve turn-off discharge circuit, and details will not be repeated here.

[0038] The above are only preferred embodiments of the present invention, and the present invention is not limited to other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A solenoid valve turn-off discharge circuit, comprising a driving module DRV, a solenoid valve coil L0, and a solenoid valve switch M0, characterized in that, it further comprises: a current mirror module for providing a discharge condition when a back electromotive force is generated in the solenoid valve coil L0, the current mirror module including a first current branch and a second current branch; One end of the first current branch is connected to one end of the solenoid valve coil L0 and is connected to the power supply voltage VCC, and the other end of the first current branch is grounded; One end of the second current branch is connected to the other end of the solenoid valve coil L0 through node B, and the other end of the second current branch is connected to the positive end of the unidirectional conduction module; A unidirectional conduction module, whose negative end is connected to the control end of the solenoid valve switch M0. When the solenoid valve switch M0 is turned off and a back electromotive force is generated in the solenoid valve coil L0, the back electromotive force provides an opening voltage for the control end of the solenoid valve switch M0 through the second current branch and the unidirectional conduction module, so that the solenoid valve switch M0 is re-conducted and the back electromotive force is quickly discharged; A clamping module, one end of which is connected to node A between the unidirectional conduction module and the control end of the solenoid valve switch M0, and the other end is grounded, for limiting the voltage generated by the back electromotive force at the control end of the solenoid valve switch M0; A driving resistance module, one end of which is connected to node A and the other end is connected to the output end of the driving module DRV, for adjusting the voltage of node A according to the output signal of the driving module DRV to control the opening and closing of the solenoid valve switch M0.

2. The solenoid valve turn-off discharge circuit according to claim 1, characterized in that, When the input signal S_CTRL of the driving module DRV is at a high level, the driving module DRV outputs an opening driving signal, and the driving resistance module raises the voltage of node A, so that the solenoid valve switch M0 is turned on and the voltage of node B decreases; At this time, due to the limitation of the unidirectional conduction module, current does not flow from node A to node B, and the power supply voltage VCC charges the solenoid valve coil L0, and the charging current of the solenoid valve coil L0 gradually rises with time until the state of the solenoid valve changes and reaches a stable state; When the input signal S_CTRL of the driving module DRV changes from a high level to a low level, the driving module DRV outputs a turn-off driving signal, and the driving resistance module pulls down the voltage of node A, so that the solenoid valve switch M0 is turned off; At this time, the back electromotive force generated by the solenoid valve coil L0 charges the parasitic capacitance of the solenoid valve switch M0 to increase the voltage of node B, the second current branch starts to conduct and the voltage of node A gradually increases. When the voltage of node A increases to re-turn on the solenoid valve switch M0, the back electromotive force generated by the solenoid valve coil L0 is quickly discharged through the solenoid valve switch M0 until the solenoid valve returns to its initial state.

3. The solenoid valve turn-off discharge circuit according to claim 1, characterized in that, The first current branch includes a first switching transistor M1 and a constant current source I0, and the second current branch includes a second switching transistor M2; the power supply voltage VCC is grounded through the first switching transistor M1 and the constant current source I0 in sequence; the control terminal of the first switching transistor M1 is connected to the control terminal of the second switching transistor M2 and connected to the input terminal of the constant current source I0 to provide a bias voltage for the second switching transistor M2 through the constant current source I0.

4. The solenoid valve turn-off discharge circuit according to claim 3, wherein, both the first switching transistor M1 and the second switching transistor M2 are PMOS transistors. The source of the first switching transistor M1 is connected to one end of the solenoid valve coil L0, and the drain is connected to the constant current source I0; the source of the second switching transistor M2 is connected to the other end of the solenoid valve coil L0, and the drain is connected to one end of the unidirectional conduction module.

5. The solenoid valve turn-off discharge circuit according to claim 4, wherein, the unidirectional conduction module includes a rectifier diode D1. The anode of the rectifier diode D1 is connected to the drain of the second switching transistor M2, and the cathode is connected to the control terminal of the solenoid valve switch M0.

6. The solenoid valve turn-off discharge circuit according to claim 5, wherein, the clamping module includes a zener diode D0. The cathode of the zener diode D0 is connected to node A, and the anode is grounded to limit the voltage generated by the back electromotive force of the solenoid valve coil L0 at node A.

7. The solenoid valve turn-off discharge circuit according to claim 6, wherein, the driving resistance module includes an initialization resistor R0 and a bias resistor R1; wherein, one end of the initialization resistor R0 is grounded, and the other end is connected to one end of the bias resistor R1 and connected to the output terminal of the driving module DRV, so as to make the voltage at the control terminal of the solenoid valve switch M0 always low before the circuit is started; the other end of the bias resistor R1 is connected to the control terminal of the solenoid valve switch M0, which is used to transfer the voltage at the control terminal of the solenoid valve switch M0 and provide a bias voltage for the control terminal of the solenoid valve switch M0 when discharging the back electromotive force.

8. The solenoid valve turn-off discharge circuit according to claim 7, wherein, the current value of the constant current source I0 is set to: ； Wherein, I0 is the current value of the constant current source, N1 / N2 is the ratio of the width-to-length ratio of the second switching transistor M2 to the first switching transistor M1, R1 is the resistance value of the bias resistor, and V TH_M0 is the conduction threshold voltage of the solenoid valve switch M0.

9. The solenoid valve turn-off discharge circuit according to any one of claims 3-8, wherein, when the input signal S_CTRL of the driving module DRV is a continuous low level, the back electromotive force discharge is completed, the driving module DRV outputs a turn-off driving signal, and after passing through the driving resistance module, the voltage at node A is pulled low, and the solenoid valve switch M0 is turned off; at this time, the voltage at node B is equal to the power supply voltage VCC, and the current IL in the solenoid valve coil L0 is 0A; When the input signal S_CTRL of the driving module DRV is at a high level, the driving module DRV outputs an enabling driving signal. After passing through the bias resistor R1, the voltage of node A becomes high level, and the solenoid valve switch M0 conducts, pulling down the voltage of node B. At this time, due to the limitation of the unidirectional conduction module, the current will not flow from node A to node B, and the power supply voltage VCC charges the solenoid valve coil L0. The current IL in the solenoid valve coil L0 gradually rises with time until the current reaches a steady state. At the moment when the input signal S_CTRL of the driving module DRV changes from high level to low level, the driving module DRV outputs a disabling driving signal, and the voltage of node A drops rapidly, turning off the solenoid valve switch M0. At this time, the back electromotive force generated by the solenoid valve coil L0 charges the parasitic capacitance of the solenoid valve switch M0, raising the voltage of node B. The second current branch starts to conduct and the voltage of node A gradually rises. When the voltage of node A rises to turn on the solenoid valve switch M0 again, the back electromotive force generated by the solenoid valve coil L0 is quickly discharged through the solenoid valve switch M0 until the energy is completely discharged, and the solenoid valve returns to its initial state, and the voltage of node B returns to the power supply voltage VCC again.

10. A solenoid valve control system characterized in that it includes the solenoid valve disabling and discharging circuit according to any one of claims 1 to 9.

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