Automobile electromagnetic valve actuator driving method and system

Abstract

The invention relates to an automobile solenoid valve actuator driving method and system, gate driver control adopts a peak protection driving mode, a boost chopper circuit applies a peak driving voltage to a solenoid valve coil, so that the coil current rises to a peak current at a first speed, and the rising time lasts to a first time point; controlling the coil current to actively attenuate to low ebb current at a second time point through a gate driver, switching to a saturation driving mode at the second time point, and applying battery voltage to the solenoid valve coil until the needle valve-moving armature ascends to the maximum displacement position; and in the holding mode, the position of the needle valve-moving armature is maintained through holding current, so that the nozzle is kept in a continuous opening state. Compared with the prior art, the system has the advantages of being long in service life, accurate in fuel injection quantity, fast in response and the like.

Description

Technical Field

[0001] This invention relates to the field of automotive drive systems, and in particular to a driving method and system for automotive solenoid valve actuators. Background Technology

[0002] Electronic fuel injectors, as core components of the engine, are typically installed in the engine manifold or on top of the cylinders. Depending on the engine's operating conditions, such as speed, load, and temperature, the engine control unit (ECU) sends different voltage or current signals to control the opening and closing of the injectors. This allows for precise control of the fuel injection quantity and timing, ensuring thorough mixing of fuel and air for efficient combustion, improving engine power performance, fuel economy, and reducing emissions. The injector is a normally closed solenoid valve. Its internal structure mainly consists of a solenoid coil, stationary armature, moving armature, and needle valve. The electrical signal from the engine control unit passes through the solenoid coil, generating an electromagnetic field that creates an electromagnetic attraction force between the stationary and moving armatures. This electromagnetic force lifts the moving armature and needle valve together, opening the injector.

[0003] Existing automotive solenoid valve actuation methods include peak-sustaining actuation and saturation actuation. Peak-sustaining actuation provides a high voltage (typically 30-70V) during the peak phase via a boost chopper circuit, supplying a large current to the solenoid coil for rapid opening. This generates a large electromagnetic force to quickly overcome opening resistance and inertia, achieving rapid valve opening. Because the voltage used during the peak phase is high and the duration until the needle valve reaches its maximum lift is long, the impact force on the moving armature is significant, leading to wear, frequent maintenance, and a short lifespan. Saturation actuation provides a constant voltage (typically battery voltage) via a switching circuit. The current rise rate is a fraction of that in peak-sustaining actuation. Depending on the resistance and inductance of the solenoid coil, the current rises at a slower rate and tends towards saturation. While the slower current rise rate makes it simpler to control and less prone to wear, the slower speed and longer process of the moving armature reaching its maximum lift result in lower precision in fuel injection control. Therefore, how to drive automotive solenoid valve actuators to reduce the impact of the moving armature while ensuring rapid valve opening, and to accurately control the opening, closing and pulling movements of the solenoid valve, is a technical problem that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a driving method and system for automotive solenoid valve actuators. By using a high-current peak protection driving mode before the needle valve-moving armature starts to move, the response of the solenoid valve is accelerated. When the needle valve-moving armature is about to start moving, the current is actively and quickly reduced to prevent the needle valve-moving armature from rushing out with high speed and acceleration. After the current actively decreases, the saturation driving mode is connected and the current is slowly increased, thereby reducing the instantaneous speed when the moving armature collides with the stationary armature and reducing the impact force.

[0005] The objective of this invention can be achieved through the following technical solutions.

[0006] According to one aspect of the present invention, a driving method for an automotive solenoid valve actuator is provided, comprising the following steps: activating via a pulse signal; controlling a peak-protection driving mode via a gate driver; applying a peak driving voltage to the solenoid valve coil via a boost chopper circuit, causing the coil current to rise to a peak current at a first speed, the rise time lasting until a first time point, the first time point being obtained based on a pre-statistically calculated time for the needle valve-moving armature to begin moving; at the first time point, controlling the coil current via the gate driver to actively decay to a low current at a second time point, the magnitude of the low current being obtained based on the current at the first time point and the pre-statistically calculated initial back electromotive force for the needle valve-moving armature to begin moving; switching to a saturation driving mode at the second time point, applying a battery voltage to the solenoid valve coil until the needle valve-moving armature rises to its maximum displacement; and in a holding mode, maintaining the position of the needle valve-moving armature by a holding current, keeping the nozzle continuously open.

[0007] Furthermore, the battery voltage in the saturation drive mode is lower than the peak drive voltage.

[0008] Furthermore, the gate driver controls the power supply path to shut down by freewheeling to the peak drive voltage source to pull down the current.

[0009] Furthermore, the first time point is obtained by calibration test on the same type of solenoid valve actuator. In the calibration test, the needle valve-moving armature generates back electromotive force at the moment of starting movement, causing the current to drop sharply. The calibration test obtains the moment when the needle valve-moving armature starts to move by measuring the time point when the coil inductance begins to rise continuously. The first time point is the measured moment when the needle valve-moving armature starts to move. At the first time point, the velocity and acceleration of the needle valve-moving armature are both zero, and it has not disengaged from the stationary armature.

[0010] Furthermore, the specific steps of the calibration experiment include: using a high-frequency periodic peak driving voltage on the solenoid valve nozzle of the experiment, the period includes a peak driving and a turn-off phase, collecting the current value at the end of the peak driving phase and the current value at the end of the turn-off phase, calculating the rate of change of current and the average current in each period, calculating the effective voltage applied across the solenoid valve coil through the average current, obtaining the real-time inductance estimate through the effective voltage and the rate of change of current, further obtaining the change in the continuous inductance estimate, when the change in several consecutive continuous inductance estimates exceeds a positive threshold, determining that the inductance begins to rise continuously, and determining the moment corresponding to the change in the first continuous inductance estimate that exceeds the positive threshold as the moment when the needle valve-moving armature begins to move.

[0011] Furthermore, the specific calculation method for the valley current is as follows: the instantaneous current, instantaneous current change rate, and effective voltage at the moment when the needle valve-moving armature begins to move are collected; the back electromotive force at the moment when the needle valve-moving armature begins to move is obtained based on the DC resistance of the solenoid valve coil, the instantaneous current at the moment when the needle valve-moving armature begins to move, and the effective voltage; the valley current provides the needle valve-moving armature with the minimum electromagnetic force required to maintain the movement of the moving armature and compensates for its initial kinetic energy; its value is obtained based on the back electromotive force and the instantaneous current at the moment of starting to move.

[0012] Furthermore, the valley current I b The expression is:

[0013] I b =k f *I(t1)+k v *V emf ,

[0014] Where, k f is the first proportionality coefficient, a dimensionless constant, used to measure the ratio of the current required to maintain motion to the current required to overcome static friction, with a value ranging from 0.2 to 0.4; I(t1) is the instantaneous current at moment t1 when the needle valve-moving armature begins to move; k v The second proportionality coefficient, measured in volts, is the compensation gain of the back electromotive force on the target current, used to fine-tune the valley current based on the initial dynamics.

[0015] Furthermore, after the holding mode ends, the pulse signal switches to a negative high-potential power supply voltage, that is, the value is consistent with the negative peak drive voltage, the needle valve needle valve-moving armature falls back to the initial position, and the nozzle closes.

[0016] Furthermore, the duration of the hold mode can be set according to the required fuel injection volume.

[0017] According to another aspect of the present invention, an automotive solenoid valve actuator drive system is provided. The system includes an engine controller, a coil connector, a stationary armature, a solenoid coil, a moving armature, and a needle valve. The control circuit includes a boost chopper circuit (peak protection drive circuit) that outputs a peak drive voltage, a saturation drive circuit that outputs a battery voltage, and a gate limit controller for controlling the voltage across the solenoid coil, thereby controlling the movement of the needle valve-moving armature. Specifically, the system includes: activating via a pulse signal; the gate driver controlling the peak protection drive mode; and the boost chopper circuit applying a peak drive voltage to the solenoid valve coil, causing the coil current to rise to the peak voltage at a first speed. The flow rate rises to a first time point, which is obtained based on the pre-statistically calculated time when the needle valve-moving armature begins to move. At the first time point, the gate driver control coil current actively decays to a low current at the second time point. The magnitude of the low current is obtained based on the current at the first time point and the pre-statistically calculated initial back electromotive force at the start of the needle valve-moving armature movement. At the second time point, the system switches to saturation drive mode, applying battery voltage to the solenoid valve coil until the needle valve-moving armature rises to its maximum displacement. In holding mode, the position of the needle valve-moving armature is maintained by holding current, keeping the nozzle continuously open.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) By using the pre-statistical motion start time to trigger active current decay, the precise synchronization between drive mode switching and mechanical motion is achieved, avoiding the lag problem in traditional peak protection drive where the moving armature only reduces the current when it has reached the maximum position at high speed. This eliminates the "current dip" phenomenon caused by the superposition of back electromotive force and drive voltage drop, ensuring that the current drop process is smooth and controllable, and avoiding the sudden collapse of electromagnetic force. It also improves the stability and predictability of the moving armature motion, reduces impact force, and extends the service life of the equipment.

[0020] (2) Based on the current at the start of motion and the estimated back electromotive force, the target low current is dynamically calculated. The low current not only provides the minimum electromagnetic force required to maintain the inertial motion of the moving armature, but also compensates for its initial kinetic energy, realizing precise energy management and distribution. This allows the moving armature to continue moving upward smoothly and reliably until it is fully opened while achieving optimal deceleration, avoiding stalling or rebound. Under the premise of maintaining fast response characteristics, the instantaneous speed when the moving armature collides with the stationary armature is reduced, improving the durability and service life of the solenoid valve.

[0021] (3) The three modes of peak protection drive, active decay and saturation drive are organically integrated to form a hybrid drive waveform, which gives full play to the dual advantages of rapid response of peak protection drive and stable control of saturation drive. By introducing the active decay stage, a smooth transition between the two is achieved, which has the dual advantages of high response speed and low impact force. It achieves more precise control of fuel injection quantity and injection timing, improves engine power and economy, and reduces exhaust emissions. At the same time, the system is robust and can adaptively compensate for product tolerance, wear and operating condition changes. Attached Figure Description

[0022] Figure 1 Waveforms for driving automotive solenoid valve actuators;

[0023] Figure 2 This is a schematic diagram of the drive system for automotive solenoid valve actuators.

[0024] Figure 3 A circuit for driving automotive solenoid valve actuators. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] In the existing peak protection drive mode, the voltage of the boost chopper circuit is first tested to rapidly increase the current, thereby quickly increasing the magnetic force of the electromagnet and rapidly pulling the needle valve-moving armature to the stationary armature, opening the nozzle. Once the needle valve is pulled to its maximum and the nozzle is fully open, only a small electromagnetic force is needed to maintain the position of the moving armature. Therefore, switching to a lower battery voltage and adjusting the duty cycle to use a smaller holding current keeps the nozzle continuously open. The existing peak protection drive mode can quickly open the nozzle, making flow control more accurate, but due to the use of high voltage and high current, the impact force on the moving armature is large, and the armature is prone to wear.

[0027] Existing saturation drive systems rely entirely on power supply voltage. During the needle valve-moving armature rising phase, battery voltage provides the electromagnetic force required for the rise. Due to the low voltage, the time to reach the required current is long, as is the time to overcome the static friction of the moving armature and the time to reach the maximum lift. Once the needle valve-moving armature reaches its peak, saturation drive is used to maintain the position of the moving armature. The saturation drive control strategy is simple, and due to the low current, the impact force is correspondingly low, making the moving and stationary armatures less prone to wear. However, because the current rises slowly, the response and movement speeds are also slow, resulting in lower injection accuracy.

[0028] To provide a driving method with fast response and high injection accuracy, this embodiment provides a driving method for automotive solenoid valve actuators. Specific steps include: activating via a pulse signal; controlling the gate driver to adopt a peak-protection driving mode; applying a peak driving voltage to the solenoid valve coil via a boost chopper circuit, causing the coil current to rise to the peak current at a first speed, with the rise time lasting until a first time point, which is obtained based on a pre-statistically calculated time for the needle valve-moving armature to begin moving; at the first time point, controlling the gate driver to actively decay the coil current to a low current at a second time point, the magnitude of which is obtained based on the current at the first time point and the pre-statistically calculated initial back electromotive force of the needle valve-moving armature to begin moving; switching to a saturation driving mode at the second time point, applying battery voltage to the solenoid valve coil until the needle valve-moving armature rises to its maximum displacement; in holding mode, maintaining the position of the needle valve-moving armature by a holding current, keeping the nozzle continuously open.

[0029] The overall drive waveform of the automotive solenoid valve actuator in this embodiment is as follows: Figure 1 As shown, by organically combining peak protection drive and saturation drive, a reliable, fast, and significantly reduced impact velocity between the needle valve's moving armature and stationary armature is achieved, thereby reducing the impact force and significantly improving the durability of the critical components, the moving and stationary armatures. Starting from time t0, the pulse signal is activated, with a peak drive voltage of V. p The corresponding peak current I a The first time point is t1, at which point the needle valve-moving armature is just about to begin rising. Starting from the first time point t1, the current is rapidly pulled down to the low current I by using a freewheeling current source connected to the peak drive voltage. b This is the second time point, t2. The rising speed of the needle valve-moving armature decreases, and the current is slowly increased to the saturation current I using the saturation drive mode. c At time t4, the drive mode switches back from saturation drive to hold mode in peak protection drive and remains for a period of time until time t5. At this time, the pulse signal switches to a negative high potential power supply voltage, which is consistent with the negative peak drive voltage. The needle valve falls back to the initial position, causing the nozzle to close quickly. The closing speed is much higher than when the voltage on both sides of the nozzle is 0, thus achieving more precise injection control.

[0030] In saturated drive mode, the battery voltage is lower than the peak drive voltage. The gate driver controls the power supply path to shut off, and by freewheeling to the peak drive voltage source, the current is pulled down. The current actively decays to the valley current at a relatively large rate, which is an active and rapid decay.

[0031] The first time point was obtained by calibration tests on solenoid valve actuators of the same model. In the calibration test, the needle valve-moving armature generates a back electromotive force at the moment of starting to move, causing the current to drop sharply. The calibration test obtained the moment when the needle valve-moving armature started to move by measuring the time point when the coil inductance began to rise continuously. The first time point is the measured moment when the needle valve-moving armature started to move. At the first time point, the velocity and acceleration of the needle valve-moving armature are both zero, and it has not yet disengaged from the stationary armature.

[0032] The specific steps of the calibration experiment include: using a high-frequency periodic peak drive voltage on the solenoid valve nozzle, with the period including peak drive and off phases; collecting the current value at the end of the peak drive phase and the current value at the end of the off phase; calculating the rate of change of current and the average current within each cycle; calculating the effective voltage applied across the solenoid valve coil using the average current; and obtaining the real-time inductance estimate using the effective voltage and the rate of change of current. In the initial drive phase, the moving armature does not move, and the inductance value fluctuates slightly near a low baseline. Once the moving armature begins to move, a continuous, monotonically increasing trend begins. By obtaining the change in the continuous inductance estimate, when the change in several consecutive continuous inductance estimates exceeds a positive threshold, it is determined that the inductance has begun a continuous upward trend. The moment corresponding to the change in the first continuous inductance estimate exceeding the positive threshold is determined as the moment when the needle valve-moving armature begins to move.

[0033] The real-time inductance estimation value L est The expression for (t) is:

[0034]

[0035] Where V is the effective voltage applied across the solenoid valve coil, dI / dt is the rate of change of the current during this period, and T... sw ΔI represents the switching period, and ΔI represents the change in current.

[0036] In existing peak-holding drives, the moving armature-needle valve assembly is typically in high-speed motion when switching from peak high voltage to holding low voltage. According to the law of electromagnetic induction, a back electromotive force (EMF) is generated at this time, moving in the opposite direction to the drive voltage. The switching action causes the effective drive voltage applied across the coil to drop from the high peak voltage to the lower holding voltage. According to the voltage equation of the drive circuit, at the instant of switching, the back EMF and the sudden voltage drop work together to form a strong reverse voltage difference across the coil. This reverse voltage difference generates a very large negative current change rate, causing the coil current to drop much faster than the normal decay rate, thus creating a noticeable "dip" or "collapse" in the current waveform.

[0037] This embodiment fundamentally avoids current dips through a hybrid drive method. Pre-calibration tests precisely pinpoint the moment the needle valve-moving armature begins to move; this is the starting point of mechanical motion, at which both velocity and back EMF are zero. In drive control, current decay is triggered at this first moment, rather than after movement, ensuring the switching action occurs before back EMF is generated. During active decay control, the voltage duty cycle is actively controlled, causing the current to decay at a rate greater than that of the natural freewheeling mode. The trough current is dynamically calculated. Its magnitude is related to the current at the start of motion and the estimated back EMF, providing both the minimum electromagnetic force to maintain motion and compensating for initial kinetic energy, ensuring a smooth transition of the current to the saturation drive mode and avoiding reaction forces or sudden changes in motion. Because the current is actively and controllably reduced before back EMF is generated, the uncontrolled current decay problem caused by reverse voltage difference in traditional drives is avoided, resulting in a smooth current waveform without collapse. By precisely controlling the decay rate and target value of the current, the moving armature-needle valve assembly, supported by electromagnetic force, completes its opening stroke at a controllable and reduced speed, ultimately contacting the stationary armature at a lower instantaneous speed. This reduces impact force and wear, improving the actuator's durability and reliability. In summary, this application solves a long-standing inherent problem in traditional drive methods through an innovative control timing and strategy, comprehensively improving the performance of solenoid valve actuators.

[0038] The specific calculation method for the trough current is as follows: collect the instantaneous current, instantaneous current change rate, and effective voltage at the moment when the needle valve-moving armature starts to move; obtain the back electromotive force at the moment when the needle valve-moving armature starts to move based on the DC resistance of the solenoid valve coil, the instantaneous current, and the effective voltage at the moment when the needle valve-moving armature starts to move; the trough current provides the needle valve-moving armature with the minimum electromagnetic force required to maintain the movement of the moving armature and compensates for its initial kinetic energy; its value is obtained based on the back electromotive force and the instantaneous current at the moment when the movement begins.

[0039] Low current I b The expression is:

[0040] I b =k f *I(t1)+k v *V emf ,

[0041] Where, k f is the first proportionality coefficient, a dimensionless constant, used to measure the ratio of the current required to maintain motion to the current required to overcome static friction, with a value ranging from 0.2 to 0.4; I(t1) is the instantaneous current at moment t1 when the needle valve-moving armature begins to move; k v The second proportionality coefficient, measured in volts, is the compensation gain of the back electromotive force on the target current, used to fine-tune the valley current based on the initial dynamics.

[0042] After the mode is maintained,

[0043] When the pulse signal switches to a negative high-point power supply voltage, i.e., the value is consistent with the negative peak drive voltage, the needle valve falls back to the initial position, causing the nozzle to close quickly. The closing speed is much higher than when the voltage on both sides of the nozzle is 0, achieving more precise injection control. The duration of the holding mode is set according to the required injection quantity.

[0044] This embodiment also provides a drive system for automotive solenoid valve actuators, such as... Figure 2 As shown, it includes an engine controller, a coil connector, a stationary armature, an electromagnetic coil, a moving armature, and a needle valve.

[0045] like Figure 3 As shown, the control circuit includes a boost chopper circuit (peak protection drive circuit) that outputs peak drive voltage, a saturation drive circuit that outputs battery voltage, and a gate limit controller. These are used to control the voltage across the electromagnetic coil, thereby controlling the movement of the needle valve-moving armature. Specifically, the circuit includes: activating via a pulse signal; the gate driver controls the peak protection drive mode; the boost chopper circuit applies a peak drive voltage to the electromagnetic valve coil, causing the coil current to rise to the peak current at a first speed, with the rise time lasting until a first time point, which is obtained based on a pre-statistically calculated time when the needle valve-moving armature begins to move; at the first time point, the gate driver controls the coil current to actively decay to a low current at a second time point, the magnitude of which is obtained based on the current at the first time point and the pre-statistically calculated initial back electromotive force of the needle valve-moving armature; at the second time point, switching to the saturation drive mode, applying battery voltage to the electromagnetic valve coil until the needle valve-moving armature rises to its maximum displacement; in the holding mode, maintaining the position of the needle valve-moving armature by holding current, keeping the nozzle continuously open.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of driving an automotive solenoid valve type actuator, characterized by, The specific steps include: turning on by pulse signal, controlling the gate driver to adopt peak holding driving mode, applying peak driving voltage to the solenoid valve coil by the boost chopper circuit, making the coil current rise to peak current at a first speed, and the rising time lasts to a first time point, the first time point is obtained according to the time when the needle valve-moving armature starts to move which is pre-counted; at the first time point, the coil current is actively attenuated to a trough current at a second time point by the gate driver control, the size of the trough current is obtained according to the current at the first time point and the initial counter electromotive force when the needle valve-moving armature starts to move which is pre-counted; at the second time point, the saturated driving mode is switched to, the battery voltage is applied to the solenoid valve coil until the needle valve-moving armature rises to the maximum displacement; in the maintaining mode, the position of the needle valve-moving armature is maintained by the maintaining current, so that the nozzle is kept in a continuously open state.

2. The method of claim 1, wherein the method further comprises: The battery voltage in the saturated driving mode is lower than the peak driving voltage.

3. The method of claim 1, wherein the method further comprises: The gate driver control turns off the power supply path and pulls down the current by freewheeling to the peak driving voltage source.

4. The method of claim 1, wherein the method further comprises: The first time point is obtained by calibration test on the same type of electromagnetic valve type actuator, in the calibration test, the counter electromotive force is generated when the needle valve-moving armature starts to move, so that the current is suddenly reduced, the calibration test obtains the time when the needle valve-moving armature starts to move by measuring the time point when the coil inductance starts to continuously rise, the first time point is the measured time when the needle valve-moving armature starts to move, at the first time point, the speed and acceleration of the needle valve-moving armature are both zero, and the needle valve-moving armature does not move away from the static armature.

5. The method of claim 4, wherein the method further comprises: The specific steps of the calibration test include: using a high-frequency periodic peak driving voltage on the experimental solenoid valve nozzle, the period includes peak driving and off stage, collecting the current value at the end of the peak driving stage and the current value at the end of the off stage, calculating the current change rate and average current in each period, calculating the effective voltage applied across the solenoid valve coil by the average current, obtaining the real-time inductance estimation value by the effective voltage and the current change rate, further obtaining the change amount of the continuous inductance estimation value, when the change amount of the continuous inductance estimation value exceeds the positive threshold value for several consecutive times, it is determined that the inductance starts to continuously rise, and the time corresponding to the first continuous inductance estimation value that exceeds the positive threshold value is determined as the time when the needle valve-moving armature starts to move.

6. The method of claim 1, wherein the method further comprises: The specific calculation method of the trough current is to collect the instantaneous current, instantaneous current change rate and effective voltage at the time when the needle valve-moving armature starts to move, obtain the counter electromotive force at the time when the needle valve-moving armature starts to move according to the direct current resistance of the solenoid valve coil, the instantaneous current at the time when the needle valve-moving armature starts to move and the effective voltage, the trough current provides the minimum electromagnetic force required to maintain the movement of the needle valve-moving armature, and compensates for the initial kinetic energy, the value is obtained according to the counter electromotive force and the instantaneous current at the time when the needle valve-moving armature starts to move.

7. The method of claim 6, wherein the method further comprises: Low valley current I b The expression for I is: I b = k f * I(t1) + k v * V emf , wherein k f is a first proportional coefficient, is a dimensionless constant for maintaining the ratio of the current required for movement to the current required to break static friction, and has a value ranging from 0.2 to 0.4; I(t1) is the instantaneous current at the time t1 when the needle valve-movable armature starts to move; k v is a second proportional coefficient, with units of volts per volt, V emf is a back electromotive force compensation gain for the target current, for fine-tuning the trough current according to the initial movement.

8. The method of claim 1, wherein the method further comprises: After the maintaining mode ends, the pulse signal is switched to a high potential power voltage with a negative value, that is, the value is consistent with the negative peak driving voltage, the needle valve needle valve-moving armature falls to the initial position, and the nozzle is closed.

9. The method of claim 8, wherein the method further comprises: The duration of the maintaining mode is set according to the required oil injection amount.

10. A system for the method of claim 1 to 9, characterized in that The system comprises an engine controller, a coil connector, a static armature, an electromagnetic coil, a dynamic armature and a needle valve, the control circuit comprises a boost chopper circuit for outputting a peak driving voltage, a saturation driving circuit for outputting a battery voltage and a gate limit controller for controlling the voltage across the electromagnetic coil and thus the movement of the needle valve-dynamic armature, specifically comprising: through a pulse signal opening, the gate driver controls the peak preservation driving mode, the boost chopper circuit applies a peak driving voltage to the electromagnetic valve coil, and the coil current rises to a peak current at a first speed, and the rising time lasts to a first time point, the first time point is obtained according to the pre-statistical time of the start of the movement of the needle valve-dynamic armature; at the first time point, the gate driver controls the coil current to actively decay to a trough current at a second time point, the size of the trough current is obtained according to the current at the first time point and the pre-statistical initial counter electromotive force of the start of the movement of the needle valve-dynamic armature; at the second time point, the saturation driving mode is switched to, the battery voltage is applied to the electromagnetic valve coil until the needle valve-dynamic armature rises to the maximum displacement; in the maintaining mode, the position of the needle valve-dynamic armature is maintained by the maintaining current, so that the nozzle is kept in a continuously open state.

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