Hysteresis current control oil injection circuit and control method thereof

Abstract

The invention provides a hysteresis current control oil injection circuit and a control method thereof. The hysteresis current control oil injection circuit is composed of a driving signal logic module, a power driving module, a current sampling module and a voltage comparison module in a cooperative mode. According to the invention, electronic elements such as the general gate driving unit and the operational amplifier are adopted, current control can be flexibly realized by adjusting the signal duty ratio of the pulse width modulation signal, the circuit structure is simplified, and the hardware cost is reduced. A hysteresis comparator is combined with a filtering design, so that load current noise is effectively suppressed, the fuel injection current is dynamically and accurately adjusted around a set value, and the control stability is improved; the microcontroller does not need to directly control a power tube switch and collect a current signal, only needs to control the single oil injection time, remarkably reduces resource occupation, and guarantees the accuracy of the oil injection time and the reliability of all-condition current monitoring by matching with the rapid energy discharge design of a clamping diode and a normally-open continuous sampling mechanism of a low-side MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The method is suitable for various engine oil injection control scenes.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a hysteresis current-controlled fuel injection circuit and its control method. Background Technology

[0002] In automotive electronics, the precise control of fuel injectors directly impacts engine fuel economy and emissions performance, and the operating state of fuel injectors largely depends on the precise regulation of their load current. Most existing fuel injection control circuits rely on dedicated fuel injection chips for power drive and current control, especially in 24V automotive systems where the technological dependence on these dedicated chips is extremely high. This not only limits the flexibility of circuit design but can also affect production schedules due to chip supply issues. Furthermore, the high cost of dedicated chips increases the overall economic burden of the solution. Under traditional control logic, the microcontroller unit (MCU) needs to directly control the switching action of the power transistors to regulate the load current, while also needing to collect the current signal from the fuel injection circuit in real time for closed-loop control. This results in a significant consumption of the MCU's computing and I / O resources, affecting the normal operation of other electronic control functions in the vehicle. The load current is susceptible to electromagnetic interference during transmission and sampling, generating noise. Traditional circuits lack effective noise suppression mechanisms, leading to decreased current control accuracy, which in turn affects the accuracy of injection timing and quantity, ultimately impacting engine operating stability. Summary of the Invention

[0003] Therefore, it is necessary to provide a hysteresis current control fuel injection circuit and its control method to address the above-mentioned technical problems.

[0004] A hysteresis current-controlled fuel injection circuit, characterized in that it comprises: a microcontroller unit, a drive signal logic module, a power drive module, a current sampling module, and a voltage comparison module;

[0005] The microcontroller unit is connected to the drive signal logic module, the power drive module, and the voltage comparison module respectively, and is used to output a fuel injection enable signal and a pulse width modulation signal; wherein, the fuel injection enable signal is transmitted to the drive signal logic module and the power drive module, and the pulse width modulation signal is transmitted to the voltage comparison module to obtain a first comparison drive signal;

[0006] The drive signal logic module is connected to the microcontroller, the power drive module and the voltage comparison module respectively, and is used to receive the fuel injection enable signal and the first comparison drive signal, and convert them into the first high-side MOSFET drive enable signal of the power drive module.

[0007] The power drive module is connected to the fuel injector and is used to convert the first high-side MOSFET drive enable signal into a high-side MOSFET gate drive voltage and a low-side MOSFET gate drive voltage. The fuel injector is driven to inject fuel according to the high-side MOSFET gate drive voltage and the low-side MOSFET gate drive voltage. Its output terminal is connected to the current sampling module.

[0008] The current sampling module is used to collect the load current of the power drive module and convert it into a voltage signal, which is then fed back to the voltage comparison module.

[0009] The voltage comparison module is used to filter the pulse width modulation signal and convert it into an analog voltage signal, and then perform a hysteresis comparison with the voltage signal to output a second comparison drive signal to the drive signal logic module.

[0010] The drive signal logic module, in conjunction with the fuel injection enable signal and the second comparison drive signal, jointly controls the fuel injection time and operating current of the fuel injection circuit.

[0011] In one embodiment, the power drive module includes: a gate drive unit, a high-side N-channel MOSFET Q1, and a low-side N-channel MOSFET Q2;

[0012] The gate driving unit includes a high-side drive and a low-side drive, which are respectively connected to the gates of the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2. The high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2 are turned on based on the gate driving voltage of the high-side MOSFET and the gate driving voltage of the low-side MOSFET, so as to jointly drive the injector load.

[0013] During fuel injection, the low-side drive controls the low-side N-channel MOSFET Q2 to remain normally open, and the high-side drive controls the high-side N-channel MOSFET Q1 to switch between on and off, so as to maintain the injector load current near the set value.

[0014] In one embodiment, the power drive module further includes: a freewheeling diode D1 and a clamping diode D2;

[0015] The freewheeling diode D1 is used to provide a freewheeling path for the injector load current when the high-side drive is turned off, and the clamping diode D2 is used to release the injector load inductance energy at the end of injection to quickly shut off the injector.

[0016] In one embodiment, the current sampling module includes: a precision low-temperature drift power resistor R7, an operational amplifier, resistors R4, R6, R8, and R11;

[0017] The precision low-temperature drift power resistor R7 is connected to the source of the low-side N-channel MOSFET Q2. During fuel injection, the low-side N-channel MOSFET Q2 remains normally open, and the fuel injector load current flows through the precision low-temperature drift power resistor R7.

[0018] The operational amplifier, together with resistors R4, R6, R8, and R11, forms an amplification circuit that converts the current signal across the precision low-temperature drift power resistor R7 into a voltage signal. This voltage signal satisfies the following formula:

[0019]

[0020] Among them, V SO V represents a voltage signal. REF R4, R6, R8, and R11 represent the resistance values ​​of resistors R4, R6, R8, and R11, respectively. R7 represents the resistance value of the precision low-temperature drift power resistor R7. i represents the injector load current flowing through the precision low-temperature drift power resistor R7.

[0021] In one embodiment, the voltage comparison module includes: a filter circuit, an integrator circuit, a comparator, a pull-up resistor R5, and a hysteresis parameter resistor R3;

[0022] The filtering circuit consists of resistor R2 and capacitor C1, and is connected to the positive input terminal of the comparator. It is used to filter the voltage signal output by the current sampling module.

[0023] The integrating circuit is a first-order integrating circuit composed of resistor R9 and capacitor C2 or a second-order integrating circuit composed of resistor R9, capacitor C2, resistor R10 and capacitor C3, which is connected to the negative input terminal of the comparator and is used to integrate the pulse width modulation signal to convert it into an analog voltage signal.

[0024] The comparator is used to compare the voltage signal with the analog voltage signal, control the switching state of the high-side N-channel MOSFET Q1, and realize the automatic adjustment of the injector load current around the set value.

[0025] The hysteresis parameter resistor R3 is connected in parallel with the comparator, and the pull-up resistor R5 is connected to the output port of the comparator; the resistance value of the hysteresis parameter resistor R3 is greater than that of the pull-up resistor R5.

[0026] In one embodiment, the comparator sets a hysteresis parameter using the hysteresis parameter resistors R3 and R2, the hysteresis parameter satisfying the following formula:

[0027]

[0028] Wherein, the ΔVSO R1 represents the hysteresis voltage, R2 represents the resistance value of resistor R2, and R3 represents the resistance value of the hysteresis parameter resistor R3.

[0029] In one embodiment, the drive signal logic module, in conjunction with the fuel injection enable signal and the second comparison drive signal, jointly controls the fuel injection time and operating current of the fuel injection circuit, including:

[0030] The drive signal logic module uses a two-ended AND gate logic gate. The two inputs of the two-ended AND gate logic gate are respectively connected to the fuel injection enable signal output by the microcontroller unit and the second comparison drive signal output by the voltage comparison module. The output of the AND gate is connected to the high-side gate drive input of the gate drive unit. The fuel injection enable signal output by the microcontroller unit is simultaneously connected to the low-side gate drive input of the gate drive unit. When the fuel injection enable signal is high, the gate drive unit controls the low-side N-channel MOSFET Q2 to always be turned on, and the high-side N-channel MOSFET Q1 is switched by the second high-side MOSFET drive enable signal. When the fuel injection enable signal is low, the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2 are simultaneously turned off, and the fuel injector discharges energy through the clamping diode D2.

[0031] A hysteresis current-controlled fuel injection method, based on a hysteresis current-controlled fuel injection circuit as described above, includes the following steps:

[0032] S1, the microcontroller outputs a fuel injection enable signal and a pulse width modulation signal; wherein, the fuel injection enable signal is transmitted to the drive signal logic module and the power drive module, and the pulse width modulation signal is transmitted to the voltage comparison module to obtain a first comparison drive signal;

[0033] S2, the drive signal logic module receives the fuel injection enable signal and the first comparison drive signal, and converts them into the first high-side MOSFET drive enable signal of the power drive module;

[0034] S3, the power drive module converts the first high-side MOSFET drive enable signal into a high-side MOSFET gate drive voltage and a low-side MOSFET gate drive voltage, and drives the injector to inject oil according to the high-side MOSFET gate drive voltage and the low-side MOSFET gate drive voltage. Its output terminal is connected to the current sampling module.

[0035] S4, the current sampling module collects the load current of the power drive module and converts it into a voltage signal, which is then fed back to the voltage comparison module;

[0036] S5, the voltage comparison module is used to filter the pulse width modulation signal and convert it into an analog voltage signal, and then perform a hysteresis comparison with the voltage signal to output a second comparison drive signal to the drive signal logic module;

[0037] S6, the drive signal logic module, in conjunction with the fuel injection enable signal and the second comparison drive signal, jointly controls the fuel injection time and operating current of the fuel injection circuit.

[0038] In one embodiment, step S5 includes:

[0039] When the voltage signal is higher than the analog voltage signal, the second comparison drive signal outputs a high level, the high-side N-channel MOSFET Q1 turns on, and the injector load current increases; when the voltage signal is lower than the analog voltage signal, the second comparison drive signal outputs a low level, the high-side N-channel MOSFET Q1 turns off, and the injector load current decreases through the freewheeling diode D1.

[0040] In one embodiment, step S6 includes:

[0041] The microcontroller switches the fuel injection enable signal to a low level, and drives the power drive module through the signal logic module to control the high-side N-channel MOSFET Q1 to turn off. At the same time, it drives the power drive module to control the low-side N-channel MOSFET Q2 to turn off. The energy of the fuel injector load inductor is quickly discharged through the clamping diode D2, and the fuel injector load current drops to 0 within a preset time, thus achieving precise shut-off of the fuel injector.

[0042] Compared to existing technologies, the advantages and beneficial effects of this invention are as follows: This invention uses general-purpose electronic components such as gate drive units, amplifiers, and comparators to replace dedicated fuel injection chips, which not only eliminates the technological dependence on dedicated fuel injection chips and reduces hardware costs and supply chain risks, but also improves the versatility and compatibility of circuit design; by using comparator circuits combined with filtering design, load current noise is effectively suppressed, and the load current is dynamically adjusted around the set value through high-side MOSFET automatic switching control, which greatly improves the stability and accuracy of fuel injection current control; the circuit design does not require a dedicated boost circuit, and current control can be flexibly achieved by adjusting the duty cycle of the pulse width modulation signal, which significantly simplifies the circuit structure, and the microcontroller does not need to directly control the power transistor switching and collect current signals, but only needs to control the single fuel injection time, which greatly reduces the resource occupation of the microcontroller by fuel injection control and improves the operating efficiency of the microcontroller; in addition, the clamping diode achieves rapid energy discharge at the end of fuel injection, and the low-side MOSFET normally open design achieves continuous current sampling, which further ensures the accurate control of fuel injection time and the reliability of current monitoring under all operating conditions, thus optimizing the overall performance and practicality of the fuel injection system. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a hysteresis current-controlled fuel injection circuit in one embodiment;

[0044] Figure 2 This is a circuit diagram of a hysteresis current-controlled fuel injection circuit in one embodiment.

[0045] Figure 3 This is a logic timing diagram of a hysteresis current-controlled fuel injection method in one embodiment. Detailed Implementation

[0046] Before describing the specific embodiments of the present invention, the overall concept of the present invention will be explained as follows:

[0047] This invention is mainly about the development of fuel injection control process. Currently, existing fuel injection control solutions in 24V systems rely heavily on dedicated chips and have poor current noise suppression, making it difficult to balance control accuracy and cost-effectiveness.

[0048] The inventors discovered through analysis that the main reason for these problems is that existing solutions over-rely on the integrated drive and control functions of dedicated fuel injection chips, lacking flexible adaptation designs for general-purpose components. The microcontroller unit is burdened with the dual tasks of directly controlling the power transistor switch and acquiring current in real time, resulting in redundant control logic. Furthermore, there is a lack of targeted suppression mechanisms for load current noise, with control accuracy decreasing due to simple sampling feedback. If general-purpose gate-driven devices can be used instead of dedicated chips, and a hysteresis comparator circuit can be used to achieve automatic current adjustment, controlling the target current through signal duty cycle, simplifying the microcontroller unit's control tasks, and incorporating dedicated filtering design, the aforementioned problems can be avoided.

[0049] Therefore, this invention proposes a hysteresis current-controlled fuel injection circuit and control method. The circuit includes a drive signal logic module, a power drive module, a current sampling module, and a voltage comparison module. By combining the fuel injection enable signal and pulse width modulation signal output by the microcontroller, the AND operation of the drive signal logic module, the gate drive of the power drive module and the coordinated control of the N-channel MOSFET, the precise current and voltage conversion of the current sampling module, and the hysteresis comparison output of the voltage comparison module, a closed-loop control of the fuel injection time and operating current is achieved. This eliminates the need for dedicated chips and boost circuits, effectively suppresses current noise, and reduces the resource consumption of the microcontroller.

[0050] After introducing the overall concept of the present invention, 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 through specific embodiments and in conjunction with the accompanying drawings.

[0051] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in one or more embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] In one embodiment, such as Figure 1 As shown, a schematic diagram of a hysteresis current-controlled fuel injection circuit is provided, including: a microcontroller unit 1, a drive signal logic module 2, a power drive module 3, a current sampling module 4, and a voltage comparison module 5.

[0053] The microcontroller unit 1 (MCU) is connected to the drive signal logic module 2, the power drive module 3, and the voltage comparison module 5, respectively, and is used to output the fuel injection enable signal (MCU_DRV) and the pulse width modulation signal (MCU_PWM). The fuel injection enable signal is transmitted to the drive signal logic module 2 and the power drive module 3, and the pulse width modulation signal is transmitted to the voltage comparison module 5 to obtain the first comparison drive signal (COMP_DRV).

[0054] The drive signal logic module 2 is connected to the microcontroller unit 1, the power drive module 3 and the voltage comparison module 5 respectively, and is used to receive the fuel injection enable signal and the first comparison drive signal, and convert them into the first high-side MOSFET drive enable signal of the power drive module 3.

[0055] The power drive module 3 is connected to the injector and is used to convert the first high-side MOSFET drive enable signal into the high-side MOSFET gate drive voltage and the low-side MOSFET gate drive voltage. Based on the high-side MOSFET gate drive voltage and the low-side MOSFET gate drive voltage, the injector is driven to inject oil. Its output terminal is connected to the current sampling module 4.

[0056] The current sampling module 4 is used to collect the load current of the power drive module 3 and convert it into a voltage signal (V). SO The feedback is sent to voltage comparison module 5.

[0057] The voltage comparison module 5 is used to filter the fuel injection enable signal and convert it into an analog voltage signal. After performing a hysteresis comparison with the voltage signal, it outputs a second comparison drive signal (COMP_DRV') and sends it to the drive signal logic module 2. The drive signal logic module 2 converts the second comparison drive signal into a second high-side MOSFET drive enable signal of the power drive module 3.

[0058] The power drive module 3, together with the fuel injection enable signal and the second high-side MOSFET drive enable signal, controls the fuel injection time and operating current of the fuel injection circuit.

[0059] In one embodiment, the circuit diagram further includes a vehicle load power supply providing power to the power drive module 3, and a reference voltage source providing a reference voltage to the current sampling module 4.

[0060] like Figure 2 As shown, a schematic diagram of a hysteresis current-controlled fuel injection circuit is provided.

[0061] The power drive module 3 includes: a gate drive unit GDU, a high-side N-channel MOSFET Q1, and a low-side N-channel MOSFET Q2.

[0062] The gate drive unit (GDU) can be a general-purpose independent half-bridge driver chip or an independent GDU unit in other integrated chips. The gate drive unit (GDU) includes a high-side drive and a low-side drive, which are connected to the gates of the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2, respectively.

[0063] The high-side N-channel MOSFET Q1 is located on the high-potential side of the injector power supply circuit and is the core switching device controlling the on / off state of the injector current. Its gate is controlled by the high-side MOSFET gate drive voltage output by the drive signal logic module 2. When the voltage comparator module 5 outputs a high level (high-side MOSFET gate drive voltage is high) and the fuel injection enable signal (MCU_DRV high) output by the microcontroller unit 1 is valid, Q1 is turned on, and the vehicle power supply supplies power to the injector coil through Q1, causing the injector current to rise rapidly. When the voltage comparator module 5 outputs a low level (low-side MOSFET gate drive voltage is low), Q1 is turned off, and the injector coil current forms a freewheeling circuit through the freewheeling diode D1, and the current gradually decreases. Through this cyclic switching of on and off, the fuel injection current is dynamically adjusted around the set value, ensuring precise control of the injector starting with high current during the Peak phase and maintaining fuel injection with low current during the Hold phase. The Peak phase (peak current phase) is the critical operating phase during the initial opening of the injector. Its core purpose is to quickly overcome the mechanical resistance of the injector solenoid valve by providing a large peak current, ensuring rapid injector opening and achieving precise injection initiation control. The Hold phase (holding current phase) is the core operating phase after the injector opens and before it closes. Its core purpose is to provide a stable holding current to ensure the injector solenoid valve remains open while reducing energy consumption, thus ensuring a stable and continuous injection process.

[0064] The low-side N-channel MOSFET Q2 is located on the low-potential side (close to ground) of the injector circuit and is connected in series with the precision low-temperature drift power resistor R7. Throughout the injection process (MCU_DRV high), Q2 remains normally open, ensuring that the injector load current continuously flows through the precision low-temperature drift power resistor R7, providing a stable circuit for the current sampling module 4 to collect the load current in real time. When the injection ends (MCU_DRV low), Q2 and Q1 turn off simultaneously, cutting off the normal current circuit. At this time, the inductance energy stored in the injector coil is quickly discharged through the clamping diode D2, causing the current to drop rapidly to near zero, achieving rapid and precise shut-off of the injector and avoiding injector residue.

[0065] The power drive module 3 also includes a freewheeling diode D1 and a clamping diode D2. The freewheeling diode D1 provides a freewheeling path for the injector load current when the high-side drive is off, and the clamping diode D2 discharges the inductive energy of the injector load at the end of injection to quickly shut off the injector, thereby achieving precise control of the injection timing.

[0066] The current sampling module 4 includes: a precision low-temperature drift power resistor R7, an operational amplifier OP, resistors R4, R6, R8, and R11. The operational amplifier OP and resistors are used on the low side of the circuit to convert the load current signal into a voltage signal.

[0067] A precision cryogenic power resistor R7 is connected to the source of a low-side N-channel MOSFET Q2. During fuel injection, the low-side N-channel MOSFET Q2 remains normally open, and the injector load current flows through the precision cryogenic power resistor R7. The magnitude of the load current can be continuously sampled and monitored. The value of the precision cryogenic power resistor R7 is based on the maximum differential voltage required to achieve the highest expected load current, and the resistance value can also be based on a power loss budget. Since the precision cryogenic power resistor R7 is located on the low side of the circuit, there are no special requirements for the amplifier's common-mode voltage capability and dv / dt rejection capability.

[0068] Resistors R4, R6, R8, and R11 are precision resistors. An operational amplifier, together with these resistors, forms an amplification circuit that converts the current signal across the precision low-temperature drift power resistor R7 into a voltage signal. The connection relationships of the resistors include, but are not limited to, the connections shown in this circuit diagram. This embodiment is merely a preferred configuration; any connection relationship capable of achieving this function is within the scope of this invention. The voltage signal satisfies the following formula:

[0069]

[0070] Among them, V SO V represents a voltage signal. REF This represents the reference voltage. R4, R6, R8, and R11 represent the resistance values ​​of resistors R4, R6, R8, and R11, respectively. R7 represents the resistance value of the precision low-temperature drift power resistor R7. i represents the injector load current flowing through the precision low-temperature drift power resistor R7. Typically, resistors R6 and R11 use the same resistor, and resistors R4 and R8 use the same resistor. The resistor values ​​are chosen to satisfy the condition that when i is the highest expected load current, V... SO >0; V when load current is 0 SO =V REF Therefore, the reference voltage must be set to be less than the maximum output voltage of the amplifier OP and the maximum input voltage of the comparator COMP.

[0071] Voltage comparison module 5 includes: a filter circuit, an integrator circuit, a comparator COMP, a pull-up resistor R5, and a hysteresis parameter resistor R3. The comparator COMP is used to measure the output voltage signal (V) of the current sampling circuit 4. SO The voltage is compared with the pulse width modulation signal set from the microcontroller unit. When the input voltage at the positive terminal of the comparator is higher than the set voltage, the output level is high to keep the high-side N-channel MOSFET Q1 on, and the injector current continues to rise. When the input voltage at the positive terminal of the comparator is lower than the set voltage, the output level is low to turn off the high-side N-channel MOSFET Q1, so that the injection circuit enters the freewheeling state, the injector current continues to decrease, and thus controls the injector current to automatically adjust around the set value during the injection period.

[0072] The filter circuit consists of resistor R2 and capacitor C1, and is connected to the positive input terminal of comparator COMP. It is used to filter the voltage signal output by the current sampling module.

[0073] The integrating circuit is either a first-order integrating circuit composed of resistor R9 and capacitor C2, or a second-order integrating circuit composed of resistor R9, capacitor C2, resistor R10, and capacitor C3. It is connected to the negative input terminal of comparator COMP and is used to integrate the pulse width modulation signal to convert pulse width modulation signals with different duty cycles into level signals, i.e., analog voltage signals (MCU_REF). The selection of the integrating circuit parameters requires that the time constant be significantly larger than the period of the pulse width modulation signal, while taking into account the response speed of the load current adjustment.

[0074] The comparator is used to compare the voltage signal with the analog voltage signal, control the switching state of the high-side N-channel MOSFET Q1, and realize the automatic adjustment of the injector load current around the set value.

[0075] Hysteresis parameter resistor R3 is connected in parallel with the comparator, and pull-up resistor R5 is connected to the comparator output port; the resistance value of hysteresis parameter resistor R3 is greater than that of pull-up resistor R5, so that the high-level output is close to +5V; the set value of the injector load current is determined by the average value of the pulse width modulation signal, and the ripple of the injector load current is determined by R2 and R3. Their equivalent conversion voltage uses the equation:

[0076]

[0077] ΔV SO This represents the hysteresis voltage, i.e., the voltage signal (V). SO The voltage variation range during the operation of the comparator describes the voltage range that the voltage signal needs to cross when the hysteresis comparator switches between high-level and low-level output. R2 represents the resistance value of resistor R2, and R3 represents the resistance value of the hysteresis parameter resistor R3.

[0078] The drive signal logic module 2, in conjunction with the fuel injection enable signal and the second comparison drive signal, jointly controls the fuel injection time and operating current of the fuel injection circuit. This includes: the drive signal logic module 2 employs a two-terminal AND gate logic gate. The two inputs of the AND gate logic gate are respectively connected to the fuel injection enable signal output from the microcontroller unit 1 and the second comparison drive signal output from the voltage comparison module 5. The output of the AND gate is connected to the high-side gate drive input of the gate drive unit GDU, outputting the second high-side MOSFET drive enable signal to the gate drive unit GDU. The fuel injection enable signal output from the microcontroller unit 1 is simultaneously connected to the low-side gate drive input of the gate drive unit GDU. When the fuel injection enable signal is high, the gate drive unit controls the low-side N-channel MOSFET Q2 to always be on according to the second high-side MOSFET drive enable signal, and the high-side N-channel MOSFET Q1 is controlled by the second high-side MOSFET drive enable signal. When the fuel injection enable signal is low, the gate drive unit controls the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET according to the second high-side MOSFET drive enable signal. Q2 is turned off at the same time, and the injector discharges energy through the clamping diode D2, thus ending the fuel injection.

[0079] This invention provides a hysteresis current-controlled fuel injection control circuit that uses general-purpose electronic components such as gate drive units, amplifiers, and comparators to replace dedicated fuel injection chips. This not only eliminates the technological dependence on dedicated fuel injection chips, reducing hardware costs and supply chain risks, but also improves the versatility and compatibility of the circuit design. By combining a comparator circuit with a filtering design, load current noise is effectively suppressed. Simultaneously, automatic switching control of the high-side MOSFET enables dynamic adjustment of the load current around a set value, significantly improving the stability and accuracy of fuel injection current control. The circuit design eliminates the need for a dedicated boost circuit; current control can be flexibly achieved simply by adjusting the duty cycle of the pulse width modulation signal, significantly simplifying the circuit structure. Furthermore, the microcontroller unit does not need to directly control the power transistor switching or collect current signals; it only needs to control the single fuel injection time, greatly reducing the resource consumption of the microcontroller unit and improving its operating efficiency. In addition, a clamping diode enables rapid energy discharge at the end of fuel injection, and a normally-on low-side MOSFET design enables continuous current sampling, further ensuring precise control of the fuel injection time and reliable current monitoring under all operating conditions. Overall, this optimizes the performance and practicality of the fuel injection system.

[0080] It should be noted that the above description describes some embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0081] Based on the same inventive concept, corresponding to any of the above embodiments, the present invention also provides a hysteresis current controlled fuel injection method, comprising the following steps:

[0082] S1, the microcontroller outputs a fuel injection enable signal and a pulse width modulation signal; wherein, the fuel injection enable signal is transmitted to the drive signal logic module and the power drive module, and the pulse width modulation signal is transmitted to the voltage comparison module to obtain the first comparison drive signal;

[0083] S2, the drive signal logic module receives the fuel injection enable signal and the first comparison drive signal, and converts them into the first high-side MOSFET drive enable signal of the power drive module;

[0084] S3, the power drive module converts the first high-side MOSFET drive enable signal into a high-side MOSFET gate drive voltage and a low-side MOSFET gate drive voltage, and drives the injector to inject oil according to the high-side MOSFET gate drive voltage and the low-side MOSFET gate drive voltage. Its output terminal is connected to the current sampling module.

[0085] S4, the current sampling module collects the load current of the power drive module and converts it into a voltage signal, which is then fed back to the voltage comparison module;

[0086] S5, the voltage comparison module is used to filter the pulse width modulation signal and convert it into an analog voltage signal, and then perform a hysteresis comparison with the voltage signal to output a second comparison drive signal to the drive signal logic module;

[0087] S6, the drive signal logic module, in conjunction with the fuel injection enable signal and the second comparison drive signal, jointly controls the fuel injection time and operating current of the fuel injection circuit.

[0088] Step S5 includes:

[0089] When the voltage signal is higher than the analog voltage signal, the second comparison drive signal outputs a high level, the high-side N-channel MOSFET Q1 turns on, and the injector load current increases; when the voltage signal is lower than the analog voltage signal, the second comparison drive signal outputs a low level, the high-side N-channel MOSFET Q1 turns off, and the injector load current decreases through the freewheeling diode D1.

[0090] Step S6 includes:

[0091] The microcontroller switches the fuel injection enable signal to a low level, and drives the power drive module through the signal logic module to control the high-side N-channel MOSFET Q1 to turn off. At the same time, it drives the power drive module to control the low-side N-channel MOSFET Q2 to turn off. The energy of the fuel injector load inductor is quickly discharged through the clamping diode D2, and the fuel injector load current drops to 0 within a preset time, thus achieving precise shut-off of the fuel injector.

[0092] In one embodiment, Figure 3 A logic timing diagram of a hysteresis current-controlled fuel injection method is provided, including timings T0-T7.

[0093] T0: In the pre-drive phase, the microcontroller's fuel injection enable signal (MCU_DRV) is low, the pulse width modulation signal (MCU_PWM) is high, and the drive circuit has no current output.

[0094] T1: During the drive current ramp-up phase, the microcontroller's fuel injection enable signal (MCU_DRV) is high, and the pulse width modulation signal (MCU_PWM) outputs a low duty cycle PWM wave. The drive circuit current begins to ramp up from zero to the peak current of the Peak phase.

[0095] T2: During the drive current drop-off phase, the microcontroller's fuel injection enable signal (MCU_DRV) outputs high, and the pulse width modulation signal (MCU_PWM) outputs a low duty cycle PWM wave. Under hysteresis comparator control, the drive circuit current drops from the peak current of the Peak phase to the valley current of the Peak phase.

[0096] T3: During the drive current maintenance phase, the microcontroller's fuel injection enable signal (MCU_DRV) is high, and the pulse width modulation signal (MCU_PWM) outputs a low duty cycle PWM wave. Under hysteresis comparator control, the drive circuit current fluctuates regularly between the peak current and the valley current of the Peak phase.

[0097] T1 to T3 are collectively referred to as the Peak current stage. The current value is relatively large in this stage, which is used to quickly open the injector solenoid valve.

[0098] T4: During the drive current transition phase, the microcontroller's fuel injection enable signal (MCU_DRV) outputs high, and the pulse width modulation signal (MCU_PWM) outputs a high duty cycle PWM wave. Under hysteresis comparator control, the drive circuit current transitions from the peak current of the Peak phase to the valley current of the Hold phase.

[0099] T5: During the drive current maintenance phase, the microcontroller's fuel injection enable signal (MCU_DRV) is high, and the pulse width modulation signal (MCU_PWM) outputs a high duty cycle PWM wave. Under hysteresis comparison control, the drive circuit current fluctuates regularly between the peak current in the Hold phase and the valley current in the Hold phase.

[0100] T4 to T5 are collectively referred to as the Hold current stage. The current value is relatively small during this stage, which is used to keep the injector solenoid valve open.

[0101] T6: During the rapid shutdown phase of the drive current, the microcontroller's fuel injection enable signal (MCU_DRV) output is low, while the pulse width modulation signal (MCU_PWM) output remains high. The drive circuit rapidly discharges from the Hold phase current to near 0 via the clamping diode D2, causing the fuel injector to shut off and fuel injection to end.

[0102] T7: Fuel injection ends, same as T0 stage.

[0103] The methods described above are implemented based on a hysteresis current control fuel injection control circuit in any of the foregoing embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0104] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of the invention as described above, which are not provided in the details for the sake of brevity.

[0105] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0106] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of the invention, the well-known power / ground connections to the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. Furthermore, systems may be illustrated in block diagram form to avoid obscuring the embodiments of the invention, and this also takes into account the fact that the details of implementation of these block diagram systems are highly dependent on the platform on which the embodiments of the invention will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of the invention, it will be apparent to those skilled in the art that the embodiments of the invention may be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0107] Although the invention has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0108] The embodiments of this invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this invention should be included within the protection scope of this invention.

Claims

1. A hysteresis current control fuel injection circuit, characterized by, The application relates to a fuel injection circuit, which comprises a micro control unit, a driving signal logic module, a power driving module, a current sampling module and a voltage comparison module. The micro control unit is connected with the driving signal logic module, the power driving module and the voltage comparison module respectively, and is used for outputting a fuel injection enabling signal and a pulse width modulation signal; wherein the fuel injection enabling signal is transmitted to the driving signal logic module and the power driving module, and the pulse width modulation signal is transmitted to the voltage comparison module to obtain a first comparison driving signal. The driving signal logic module is connected with the micro control unit, the power driving module and the voltage comparison module respectively, and is used for receiving the fuel injection enabling signal and the first comparison driving signal, and converting the fuel injection enabling signal and the first comparison driving signal into a first high-side MOSFET driving enabling signal of the power driving module. The power driving module is connected with a fuel injector, and is used for converting the first high-side MOSFET driving enabling signal into a high-side MOSFET gate driving voltage and a low-side MOSFET gate driving voltage, and driving the fuel injector to inject fuel according to the high-side MOSFET gate driving voltage and the low-side MOSFET gate driving voltage, and the output end of the power driving module is connected with the current sampling module. The current sampling module is used for collecting a load current of the power driving module and converting the load current into a voltage signal, and feeding back the voltage signal to the voltage comparison module. The voltage comparison module is used for converting the pulse width modulation signal into an analog voltage signal through filtering, and outputting a second comparison driving signal to the driving signal logic module after hysteresis comparison between the analog voltage signal and the voltage signal. The driving signal logic module combines the fuel injection enabling signal and the second comparison driving signal to jointly control fuel injection time and working current of the fuel injection circuit. The power driving module comprises a gate driving unit, a high-side N-channel MOSFET Q1 and a low-side N-channel MOSFET Q2.

2. The hysteresis current control fuel injection circuit according to claim 1, wherein The gate driving unit comprises a high-side driving and a low-side driving, which are connected with the gate of the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2 respectively, and turn on the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2 based on the high-side MOSFET gate driving voltage and the low-side MOSFET gate driving voltage to jointly drive the fuel injector load. During fuel injection, the low-side driving controls the low-side N-channel MOSFET Q2 to keep open, and the high-side driving controls the high-side N-channel MOSFET Q1 to switch between turn-on and turn-off to maintain the fuel injector load current around a set value. The power driving module further comprises a freewheeling diode D1 and a clamping diode D2.

3. The hysteresis current control fuel injection circuit of claim 1 wherein, The freewheeling diode D1 is used for providing a freewheeling path for the fuel injector load current when the high-side driving is turned off, and the clamping diode D2 is used for discharging the fuel injector load energy to quickly turn off the fuel injector when the fuel injection is finished. The current sampling module comprises a precision low-temperature drift power resistor R7, an operational amplifier, resistors R4, R6, R8 and R11.

4. The hysteresis current control fuel injection circuit of claim 1 wherein, ​ The precision low-temperature drift power resistor R7 is connected with the source of the low-side N-channel MOSFET Q2, during the oil injection period, the low-side N-channel MOSFET Q2 keeps open, and the oil injector load current flows through the precision low-temperature drift power resistor R7; The operational amplifier and the resistors R4, R6, R8 and R11 constitute an amplification circuit, and the current signal between the precision low-temperature drift power resistor R7 is converted into a voltage signal, and the voltage signal satisfies the following formula: ， wherein represents a voltage signal, represents a reference voltage, R4, R6, R8, R11 represent resistance values of the resistor R4, the resistor R6, the resistor R8, and the resistor R11, and R7 represents a resistance value of the precision low-temperature drift power resistor R7, represents an injector load current flowing through the precision low-temperature drift power resistor R7.

5. The hysteresis current control fuel injection circuit of claim 1 wherein, The voltage comparison module comprises a filter circuit, an integration circuit, a comparator, a pull-up resistor R5 and a hysteresis parameter resistor R3; The filter circuit is composed of a resistor R2 and a capacitor C1, and is connected with the positive input end of the comparator, and is used for filtering the voltage signal output by the current sampling module; The integration circuit is a first-order integration circuit composed of a resistor R9 and a capacitor C2, or a second-order integration circuit composed of a resistor R9, a capacitor C2, a resistor R10 and a capacitor C3, and is connected with the negative input end of the comparator, and is used for integrating the pulse width modulation signal to convert it into an analog voltage signal; The comparator is used for comparing the voltage signal with the analog voltage signal, controlling the switching state of the high-side N-channel MOSFET Q1, and realizing the automatic adjustment of the oil injector load current around the set value; The hysteresis parameter resistor R3 is connected in parallel with the comparator, and the pull-up resistor R5 is connected with the output port of the comparator; the resistance value of the hysteresis parameter resistor R3 is greater than that of the pull-up resistor R5.

6. The hysteresis current control fuel injection circuit of claim 5 wherein, The comparator sets the hysteresis parameter through the hysteresis parameter resistor R3 and the resistor R2, and the hysteresis parameter satisfies the following formula: ， Wherein, the represents the hysteresis voltage, represents the resistance R2 value, represents the hysteresis parameter resistance R3 value.

7. The hysteresis current control fuel injection circuit of claim 1 wherein, The driving signal logic module combines the oil injection enable signal and the second comparison driving signal to jointly control the oil injection time and working current of the oil injection circuit, and comprises: The driving signal logic module adopts a two-terminal input AND gate logic gate, two input ends of the two-terminal input AND gate logic gate are connected with the oil injection enable signal output by the micro control unit and the second comparison driving signal output by the voltage comparison module respectively, and an AND gate output end is connected to the high-side gate drive input end of the gate drive unit; the oil injection enable signal output by the micro control unit is also connected to the low-side gate drive input end of the gate drive unit; when the oil injection enable signal is high, the gate drive unit controls the low-side N-channel MOSFET Q2 to be always open, and the high-side N-channel MOSFET Q1 is controlled to be switched by the second high-side MOSFET driving enable signal; when the oil injection enable signal is low, the high-side N-channel MOSFET Q1 and the low-side N-channel MOSFET Q2 are closed at the same time, and the oil injector discharges energy through the clamping diode D2.

8. A hysteresis current control fuel injection method, implemented based on the hysteresis current control fuel injection circuit according to any one of claims 1-7, characterized in that, The method comprises the following steps: S1, the micro control unit outputs an oil injection enable signal and a pulse width modulation signal; wherein the oil injection enable signal is transmitted to a driving signal logic module and a power driving module, and the pulse width modulation signal is transmitted to a voltage comparison module to obtain a first comparison driving signal; S2, the driving signal logic module receives the fuel injection enable signal and the first comparison driving signal, and converts into the first high-side MOSFET driving enable signal of the power driving module; S3, the power driving module converts the first high-side MOSFET driving enable signal into the high-side MOSFET gate driving voltage and the low-side MOSFET gate driving voltage, and drives the fuel injector to inject fuel according to the high-side MOSFET gate driving voltage and the low-side MOSFET gate driving voltage, and the output end is connected with the current sampling module; S4, the current sampling module collects the load current of the power driving module and converts into the voltage signal, and feeds back to the voltage comparison module; S5, the voltage comparison module is used for converting the pulse width modulation signal into the analog voltage signal through filtering, and outputs the second comparison driving signal to the driving signal logic module after hysteresis comparison with the voltage signal; S6, the driving signal logic module combines the fuel injection enable signal and the second comparison driving signal to jointly control the fuel injection time and working current of the fuel injection circuit.

9. A method of hysteresis current control fuel injection according to claim 8, wherein, The step S5 comprises: When the voltage signal is higher than the analog voltage signal, the second comparison driving signal outputs high level, the high-side N-channel MOSFET Q1 is opened, and the fuel injector load current rises; when the voltage signal is lower than the analog voltage signal, the second comparison driving signal outputs low level, the high-side N-channel MOSFET Q1 is closed, and the fuel injector load current flows through the freewheeling diode D1 to flow down.

10. A method of hysteresis current control fuel injection according to claim 8 wherein, The step S6 comprises: The micro control unit switches the fuel injection enable signal to low level, drives the power driving module through the signal logic module to control the high-side N-channel MOSFET Q1 to be closed, at the same time, drives the power driving module to control the low-side N-channel MOSFET Q2 to be closed, the fuel injector load energy is discharged through the clamping diode D2, the fuel injector load current drops to 0 within the preset time, and the precise closing of the fuel injector is realized.

Images