GDI high-pressure oil injector power supply current calibration and inductance type selection method

Abstract

The invention discloses a GDI high-pressure oil injector power supply current calibration and inductor type selection method. The method comprises the following steps that S1, the inductor current charging slope is calculated, and the inductor discharging slope is calculated; s2, calculating the switching period of the MOS tube based on the inductive current and the inductive discharge slope; s3, the consumed energy of the GDI oil injector in the boosting stage is preset to be Ec, and the time tsw of the boosting power supply in the asynchronous stage is calculated; s4, calculating the loss of the MOS tube based on the tsw; and S5, specific parameters of the selected inductor are calculated based on the switching loss of the MOS tube, the loss condition of the MOS tube is calculated by calculating the switching period and the synchronization stage time of the boost power supply, and the optimal type selection of the inductor is calculated according to the loss feedback of the MOS tube. The GDI high-pressure oil injector power supply current calibration and inductor type selection method provided by the invention has the effect of selecting the most suitable inductor according to the temperature rise and price and calibrating the inductor current.

Description

Technical Field

[0001] The invention relates to the technical field of automobile manufacturing, and in particular to a method for calibrating a power supply current of a GDI high-pressure fuel injector and selecting an inductor. Background Art

[0002] Gasoline Direct Injection (GDI) engine, referred to as GDI engine, has been a hot spot in foreign internal combustion engine research and development in recent years. The emergence of gasoline direct injection technology has brought automobile engine technology into a new era. In the 21st century, it has the tendency to replace traditional gasoline and diesel engines and become the most ideal power unit for cars.

[0003] The GDI high-pressure injector power supply is generated by the vehicle battery power supply and the boost circuit to meet the requirements of the GDI injector's boost stage. A suitable inductor is selected in the boost circuit and a suitable boost current is calibrated to ensure that the GDI injector can operate continuously under extreme conditions and the MOS tube temperature remains within a reasonable range. Summary of the invention

[0004] In view of the above problems, a GDI high-pressure injector power supply current calibration and inductance selection method is provided to solve the problems existing in the prior art.

[0005] The specific technical solutions are as follows:

[0006] A method for calibrating a power supply current of a GDI high-pressure fuel injector and selecting an inductor, the method comprising the following steps:

[0007] S1, calculate the inductor current charging slope and the inductor discharge slope;

[0008] S2, calculating the switching cycle of the MOS tube based on the inductor current and the inductor discharge slope;

[0009] S3, presuppose that the energy consumed by the GDI injector in the boost stage is Ec, and calculate the time t when the boost power supply is in the asynchronous stage sw ;

[0010] S4, based on t sw Calculate the loss of MOS tube;

[0011] S5. Calculate and select the specific parameters of the inductor based on the switching loss of the MOS tube.

[0012] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the step S1 further includes the following steps:

[0013] S11. The specific calculation method of the inductor current charging slope is:

[0014]

[0015] Where, L: inductance;

[0016] dI: Changed current;

[0017] dt: time of change;

[0018] Vbatt: power supply voltage;

[0019] Inductor current charging slope,

[0020] S12. The specific calculation method of the inductor discharge slope is:

[0021]

[0022] Where, L: inductance;

[0023] dI: Changed current;

[0024] dt: time of change;

[0025] Vbatt: power supply voltage;

[0026] Vc: electrolytic capacitor voltage;

[0027] Vd: diode voltage drop;

[0028] Inductor discharge slope.

[0029] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the specific calculation method in step S2 is:

[0030]

[0031] Where, T: switching cycle of MOS tube;

[0032] Iboost H : Inductor current upper limit;

[0033] Iboost L : Lower limit of inductor current.

[0034] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the specific calculation method in step S3 is:

[0035]

[0036] Where, t sw : The time that the boost power supply is in the asynchronous phase.

[0037] Ec: Energy supplied by the capacitor during each injection

[0038] C: Energy storage capacitor

[0039] V1: Vboost voltage before injection boost stage

[0040] V2: Vboost voltage after injection boost stage.

[0041] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the step S4 further includes the following steps:

[0042] S41. Calculate the average loss of the MOS tube:

[0043]

[0044] Where, P: average loss of MOS tube;

[0045] k: proportionality coefficient;

[0046] S42. Calculate the loss of MOS tube:

[0047]

[0048] Where P m : Loss of MOS tube.

[0049] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the step S5 also includes the following steps:

[0050] S51, because the voltage is boosted only in the asynchronous phase, it is necessary to satisfy t sw <T inj -t boost phase , substituting into the minimum mean current in the asynchronous phase:

[0051]

[0052] Where, T inj : Average injection time interval

[0053] t boost phase : Duration of boost phase in idle state;

[0054] I async : Average current in the asynchronous phase

[0055] S52, in the idle stage, the MOS tube does not operate, the inductor current is 0, and the average value of the inductor current is:

[0056]

[0057] In the formula, I average : The mean value of the inductor current;

[0058] S53, the temperature rise current of the inductor should be greater than I average , to prevent the inductor temperature from rising too high.

[0059] S54, the saturation current of the inductor should be greater than Iboost H , to prevent the inductor from magnetic saturation.

[0060] S55, according to the loss of MOS tube, in Iboost H +Iboost L In fixed cases, Iboost H -Iboost L The larger the inductance L is, the greater the switching loss P is. m The smaller.

[0061] In summary, the beneficial effects of this scheme are:

[0062] In the GDI high-pressure fuel injector power supply current calibration and inductor selection method provided by the present invention, the loss of the MOS tube is calculated by calculating the switching cycle of the boost power supply and the synchronization phase time, and the optimal selection of the inductor is calculated according to the loss feedback of the MOS tube. The GDI high-pressure fuel injector power supply current calibration and inductor selection method provided by the present invention has the effect of selecting the most suitable inductor and inductor current calibration according to temperature rise and price. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0065] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0066] The GDI high-pressure injector power supply current calibration and inductance selection method provided in this embodiment includes the following steps:

[0067] S1, calculate the inductor current charging slope and the inductor discharge slope;

[0068] S2, calculating the switching cycle of the MOS tube based on the inductor current and the inductor discharge slope;

[0069] S3, presuppose that the energy consumed by the GDI injector in the boost stage is Ec, and calculate the time t when the boost power supply is in the asynchronous stage sw ;

[0070] S4, based on t sw Calculate the loss of MOS tube;

[0071] S5. Calculate and select the specific parameters of the inductor based on the switching loss of the MOS tube.

[0072] In the above embodiment, step S1 further includes the following steps:

[0073] S11. The specific calculation method of the inductor current charging slope is:

[0074]

[0075] Where, L: inductance;

[0076] dI: Changed current;

[0077] dt: time of change;

[0078] Vbatt: power supply voltage;

[0079] Vc: electrolytic capacitor voltage;

[0080] Vd: diode voltage drop;

[0081] Inductor discharge slope,

[0082] S12. The specific calculation method of the inductor discharge slope is:

[0083]

[0084] Where, L: inductance;

[0085] dI: Changed current;

[0086] dt: time of change;

[0087] Vbatt: power supply voltage;

[0088] Inductor discharge slope.

[0089] The above-mentioned GDI high-pressure injector power supply current calibration and inductance selection method also has the following characteristics: the specific calculation method in step S2 is:

[0090]

[0091] Where, T: switching period of MOS tube;

[0092] Iboost H : Inductor current upper limit;

[0093] Ibiist L : Lower limit of inductor current.

[0094] In the above embodiment, the specific calculation method in step S3 is:

[0095]

[0096] Where, t sw : The time that the boost power supply is in the asynchronous phase.

[0097] Ec: Energy supplied by the capacitor during each injection

[0098] C: Energy storage capacitor

[0099] V1: Vboost voltage before injection boost stage

[0100] V2: Vboost voltage after injection boost stage.

[0101] In the above embodiment, step S4 further includes the following steps:

[0102] S41. Calculate the average loss of the MOS tube:

[0103]

[0104] Where, P: average loss of MOS tube;

[0105] k: proportionality coefficient;

[0106] It should be noted that the proportionality coefficient is a constant set according to the drain slew rate of the MOS tube and the injection condition of the injector.

[0107] S42. Calculate the loss of MOS tube:

[0108]

[0109] Where P m : Loss of MOS tube.

[0110] In the above embodiment, step S5 further includes the following steps:

[0111] S51, because the voltage is boosted only in the asynchronous phase, it is necessary to satisfy t sw <T inj -t boost phase , substituting into the minimum mean current in the asynchronous phase:

[0112]

[0113] Where, T inj : Average injection time interval

[0114] t boost phase : Duration of boost phase in idle state;

[0115] I async : Average current in the asynchronous phase

[0116] S52, in the idle stage, the MOS tube does not operate, the inductor current is 0, and the average value of the inductor current is:

[0117]

[0118] In the formula, I average : The mean value of the inductor current;

[0119] S53, the temperature rise current of the inductor should be greater than I average , to prevent the inductor temperature from rising too high.

[0120] S54, the saturation current of the inductor should be greater than Iboost H , to prevent the inductor from magnetic saturation.

[0121] S55, according to the loss of MOS tube, in Iboost H +Iboost L In fixed cases, Iboost H -Iboost L The larger the inductance L is, the greater the switching loss P is. m The smaller.

[0122] Working principle, GDI fuel injection extreme conditions: power supply Vbatt low voltage 9V, engine speed 3500rpm, drive four-way injector three-time injection mode, IboostH, IboostL, L value selection must meet two conditions, 1. Under extreme conditions, before each boost phase of the injector, Vboost voltage needs to rise to 65V, 2. Under extreme conditions, high temperature 105℃ operation, MOS junction temperature needs to be lower than 175℃ Therefore, when the speed is 3500rpm, four-way injector three-time injection mode, the injection time interval T can be calculated inj :

[0123]

[0124] Since the MOS tube remains off in the idle state, that is, it needs to meet the requirements in the synchronization stage

[0125] tsw <T inj -t boost phase

[0126] Substituting the above data into the equation:

[0127]

[0128] When a GDI injector is in the boost stage, t boostphase =0.35ms, after the injection is finished, the voltage drop of the 1200uF capacitor drops from 64.5V to 61.5V, and the energy consumption of the boost power supply for a single injection is:

[0129]

[0130] Substituting in, we get:

[0131]

[0132] Therefore, Iboost H 、Iboost L The average value is 10.5A, which can meet the continuous operation under extreme conditions

[0133] Substituting the above data into the inductor selection method, the calculation can be obtained:

[0134]

[0135] When selecting an inductor, its temperature rise current must be greater than 9.5A. If the inductor has additional heat dissipation measures, the range is slightly relaxed. As the inductance L increases, or Iboost H -Iboost L Increasing it will reduce the temperature of the boost MOS tube.

[0136] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for selecting an inductor for a GDI high-pressure injector power supply, characterized in that: The method comprises the following steps: S1, calculate the inductor current charging slope and the inductor discharge slope; S2, calculating the switching cycle of the MOS tube based on the inductor current and the inductor discharge slope; S3, presuppose that the energy consumed by the GDI injector in the boost stage is Ec, and calculate the time t when the boost power supply is in the asynchronous stage sw ; S4, based on t sw Calculate the loss of MOS tube; S5. Calculate and select the specific parameters of the inductor based on the switching loss of the MOS tube.

2. The method for calibrating the power supply current and selecting the inductor of a GDI high-pressure fuel injector according to claim 1, characterized in that: The step S1 further comprises the following steps: S11. The specific calculation method of the inductor current charging slope is: Where, L: inductance; dI: Changed current; dt: time of change; Vbatt: power supply voltage; Inductor current charging slope, S12. The specific calculation method of the inductor discharge slope is: Where, L: inductance; dI: Changed current; dt: time of change; Vbatt: power supply voltage; Vc: electrolytic capacitor voltage; Vd: diode voltage drop; Inductor discharge slope.

3. A method for calibrating the power supply current and selecting the inductance of a GDI high-pressure fuel injector according to claim 2, characterized in that: The specific calculation method in step S2 is: Where, T: switching period of MOS tube; Iboost H : Inductor current upper limit; Iboost L : Lower limit of inductor current.

4. A method for calibrating the power supply current and selecting the inductance of a GDI high-pressure fuel injector according to claim 3, characterized in that: The specific calculation method in step S3 is: Where, t sw : The time that the boost power supply is in the asynchronous phase. Ec: Energy supplied by the capacitor during each injection C: Energy storage capacitor V1: Vboost voltage before injection boost stage V2: Vboost voltage after injection boost stage.

5. A method for calibrating the power supply current and selecting the inductance of a GDI high-pressure fuel injector according to claim 4, characterized in that: The step S4 further comprises the following steps: S41. Calculate the average loss of the MOS tube: Where, P: average loss of MOS tube; k: proportionality coefficient; S42. Calculate the loss of MOS tube: Where P m : Loss of MOS tube.

6. A method for calibrating the power supply current and selecting the inductance of a GDI high-pressure fuel injector according to claim 5, characterized in that: The step S5 also includes the following steps: S51, because the voltage is boosted only in the asynchronous phase, it is necessary to satisfy t sw <T inj -t boost phase , substituting into the minimum mean current in the asynchronous phase: Where, T inj : Average injection time interval t boost phase : Duration of boost phase in idle state; I async : Average current in the asynchronous phase S52, in the idle stage, the MOS tube does not operate, the inductor current is 0, and the average value of the inductor current is: In the formula, I average : The mean value of the inductor current; S53, the temperature rise current of the inductor should be greater than I average , to prevent the inductor temperature from rising too high. S54, the saturation current of the inductor should be greater than Iboost H , to prevent the inductor from magnetic saturation. S55, according to the loss of MOS tube, in Iboost H +Iboost L In fixed cases, Iboost H -Iboost L The larger the inductance L is, the greater the switching loss P is. m The smaller.

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