CN115001276B - Peak-hold driving circuit with fault diagnosis protection function and unmanned aerial vehicle engine applying peak-hold driving circuit - Google Patents

Abstract

The invention discloses a peak-hold driving circuit with fault diagnosis protection and an unmanned aerial vehicle engine applied thereto, comprising a microcontroller, a power driving unit, a current detection unit and a logic control unit, and the current detection unit and the logic control unit constitute a control unit. circuit; the microcontroller outputs the fuel injection signal, and receives the two-way comparator signals fed back by the current detection unit to complete fault diagnosis and protection; the power drive unit controls the opening and closing of the fuel injector drive circuit according to the logic signal input by the logic control unit The current detection unit outputs two comparator signals according to the detected current value; the logic control unit outputs the logic drive signal according to the fuel injection signal of the microcontroller and the two comparator signals of the current detection unit.

Description

A peak-hold drive circuit with fault diagnostic protection and its application in drone development motivation

technical field

The invention relates to a peak-hold driving circuit technology, in particular to a peak-hold driving circuit with fault diagnosis protection and an unmanned aerial vehicle engine applied thereto.

Background technique

In the UAV engine, the fuel injector applied to the port injection type has a large coil internal resistance and is usually driven by saturation voltage; while the injector applied to the direct injection method in the cylinder usually has a coil internal resistance. Smaller and more inductive, a dedicated controller is required for peak-and-hold drive. Peak-hold driving is a driving method suitable for driving any injector or even coil. The driving process is divided into two stages: the first stage adopts high-voltage driving, which increases the current rise rate of the injector coil and realizes the rapid opening of the injector; The segment is driven by low voltage or pulse width modulation, and the current of the injector coil is controlled to maintain the minimum value to ensure that the injector is turned on, and the power consumption of the coil is reduced to reduce heat generation.

The peak-hold driving circuit includes a driving circuit and a control circuit, wherein the control circuit outputs a modulation signal for controlling the driving circuit according to the current signal. There are generally three schemes for the control circuit:

The first is to use a microcontroller with a high-speed analog-to-digital conversion function. The microcontroller obtains the current value and executes the corresponding control logic according to the internal code, thereby outputting the drive signal. The advantage of this scheme is that any complex control strategy can be realized, but the disadvantage is that it requires high performance of the microcontroller, occupies a lot of resources, and needs a complete software logic strategy. For mature, stable and consistent injector products, the duty cycle of the drive in the hold current phase can be determined by calibrating the drive voltage, current and target injector parameters, thereby eliminating the need for current sampling resistors or current sensors. demand, to achieve the purpose of reducing costs, so it has been adopted in large quantities.

The second is to use a dedicated integrated chip circuit with serial peripheral interface (SPI) communication. The core microcontroller sends fuel injection instructions by means of communication, including fuel injection start time, fuel injection pulse width, peak current value, hold The number of current segments and the holding current value of each segment, the integrated chip completes the logical judgment and outputs the drive signal according to the command information and the sampling value of the built-in current sensor. The advantages of this scheme are that the integrated chip is small in size and strong in function, the microcontroller code is simple, all control parameters are adjustable and accurate, and the three-stage peak-hold current of the specified style can be easily realized. The disadvantage is that the chip is expensive and mostly Special purpose chips, generally used in high-volume production occasions with multi-stage holding current drive, are not sold in the retail market.

The third is to use discrete components to build a control circuit to achieve complete peak-hold current control based on the fuel injection signal output by the microcontroller. The control parameters of this scheme are adjustable and accurate, there is no requirement for the performance of the controller, and there is no need to modify the original microcontroller code. It is suitable for use in the early stage of the development of the fuel injector drive unit; the logic and circuit of this scheme are relatively complex, The required current sensor also adds to the cost.

SUMMARY OF THE INVENTION

Purpose of the invention: The purpose of the present invention is to solve the deficiencies in the prior art, and to provide a peak-hold drive circuit with fault diagnosis protection and a drone engine for its application. The present invention is suitable for fuel injection with low internal resistance and high inductance. device or coil.

Technical solution: A peak-hold drive circuit with fault diagnosis protection of the present invention includes a microcontroller, a power drive unit, a current detection unit and a logic control unit, and the current detection unit and the logic control unit constitute a control circuit; the current The detection unit adopts a current sense amplifier with a dual comparator, which receives the voltage signals Rs+ and Rs- at both ends of the current sampling resistor in the power drive unit, and receives the fuel injection signal Drive of the microcontroller, and then locks the first comparator. memory control, and then output the first comparator signal C1 and the second comparator signal C2 according to the current signal Current and the latch control signal, and output to the logic control unit after being pulled up by the resistor Rpu1 and the resistor Rpu2; the micro-controller The controller is integrated in the electronic control unit ECU, and the microcontroller outputs the fuel injection signal Drive and receives the two-way comparator signals (C1 and C2) and the current signal Current fed back by the current detection unit to realize fault diagnosis; the logic control unit is based on the microcontroller. The fuel injection signal Drive of the controller and the first comparator signal C1 and the second comparator signal C2 of the current detection unit output the logic signal Logical Drive; the power drive unit receives the logic signal Logical Drive of the logic control unit and the microcontroller The fuel injection signal Drive of the controller is used as the high-side drive input and the low-side drive input respectively, and the output drive signal (that is, the output signal after the half-bridge chip in the power drive unit) drives the high-side MOSFET chip QH and the low-side MOSFET chip respectively. QL, one end of the high-side MOSFET chip QH is connected to the power supply, and one end of the low-side MOSFET chip QL is connected to the power ground. The high-side MOSFET chip QH and the low-side MOSFET chip QL are also connected in turn with a current sampling resistor Rs and the connector of the injector. , and then control the turn-on and turn-off of the drive circuit.

Among them, the function of the current sense amplifier is to output the Current voltage signal from the second pin OUT after amplifying 20 times according to the voltage difference between Rs+ and Rs-. The comparators use this signal to divide the voltage and compare with the reference voltage.

与功率驱动电流

以及电流采样电阻

的关系满足：Further, the current detection unit also includes a two-way RC filter circuit composed of filter resistors Rf+ and Rf- and a filter capacitor Cf, and the voltage signal Rs+ and the voltage signal Rs- of the power drive unit are input through the two-way RC filter circuit. Current sense amplifier, the magnification of the current sense amplifier is G (V/V), (for example, if the INA203 current sense amplifier is used, its amplification power is 20V/V), then the output voltage of the current sense amplifier

with power drive current

and current-sampling resistors

The relationship satisfies:

；

;

直接接入第一路比较器，同时经过分压电阻

和分压电阻

分压后接入第二路比较器，则使得两路比较器输出高电平信号的最小驱动电流

和

分别为：The current sense amplifier integrates two comparators (including the first comparator and the second comparator, the reference voltage of the first comparator is 1.2V, and the reference voltage of the second comparator is 0.6V by default) The output voltage

Directly connect to the first comparator, and pass through the voltage divider resistor at the same time

and divider resistor

After dividing the voltage, the second comparator is connected, so that the two comparators output the minimum driving current of the high-level signal

and

They are:

；

;

；

;

以及分压电阻

和分压电阻

，使得峰值电流为

且保持电流为

；此时电流检测放大器在驱动电流高于峰值电流和保持电流时分别输出高电平的第一路比较器信号C1和第二路比较器信号C2，接着经过电阻Rpu1和电阻Rpu2上拉后输出给逻辑控制单元。Then control the current sampling resistor

and divider resistors

and divider resistor

, so that the peak current is

and the holding current is

; At this time, the current detection amplifier outputs the first comparator signal C1 and the second comparator signal C2 of high level respectively when the driving current is higher than the peak current and the holding current, and then outputs after being pulled up by the resistor Rpu1 and the resistor Rpu2 to the logic control unit.

后，第一路比较器信号C1变为高电平且被锁存，使得驱动电流I低于峰值电流

时，第一路比较器信号C1维持高电平，直至喷油信号Drive变为低电平使得锁存器复位，这一功能确保了单次峰值-保持电流驱动过程仅输出单个峰值电流波形。Further, the specific content of the latch control of the first comparator is: the latch integrated on the first comparator is controlled by the fuel injection signal Drive, when the fuel injection signal Drive is at a low level, the latch is reset, At this time, the level of the first comparator signal C1 is only related to the drive current I; when the fuel injection signal is at a high level, the latch works, that is, the drive current I reaches the peak current

After that, the first comparator signal C1 becomes high level and is latched, so that the driving current I is lower than the peak current

, the first comparator signal C1 maintains a high level until the fuel injection signal Drive becomes a low level to reset the latch. This function ensures that the single peak-hold current driving process only outputs a single peak current waveform.

Further, the logic control unit is configured with a multi-function logic gate (SN74LVC1G58), and the multi-function logic gate receives the micro-controlled fuel injection signal Drive and the first comparator signal C1 and the second comparator signal C2 of the current detection unit. , and output the logic signal Logical Drive; the multi-function logic gate is provided with In0 channel, In1 channel and In2 channel, the logic control unit changes the level of the output signal Y according to the levels of the input signals of the three channels In0, In1 and In2, and then The fuel injection signal Drive is input to the In0 channel, the second comparator signal C2 is input to the In1 channel, and the first comparator signal C1 is input to the In2 channel, and the output signal Y is the logic signal Logical Drive.

Further, the power drive unit adopts a half-bridge drive circuit, including a half-bridge drive chip UCC27212 (to realize gate drive) and a bootstrap capacitor Cboot, and the half-bridge drive chip inputs the logic signal Logical through the HI pin and the LI pin respectively. Drive and fuel injection signal Drive, and then the half-bridge driver chip outputs the drive signal through the HO pin and the LO pin respectively, and the drive signal is input to the gate of the high-side MOSFET chip QH through the gate drive resistor Rgh through the HO pin, The drive signal is input to the gate of the low-side MOSFET chip QL through the gate drive resistor Rgl through the LO pin, thereby driving the high-side MOSFET chip QH and the low-side MOSFET chip QL; the drain of the high-side MOSFET chip QH is connected to the power supply Vbst, the source is connected to the current sampling resistor Rs, and is also connected to the power ground PGND through the Schottky diode D1 to form a freewheeling loop; the low-side MOSFET chip QL source is connected to the power ground PGND, and the drain is connected to the injector. The Schottky diode D2 is connected to the power supply Vbst to form a freewheeling loop.

In the present invention, the half-bridge chip of the power drive unit acts as a drive gate, and converts the input logic signals HI and LI signals into 12V drive electrical signals HO and LO, respectively, and transmits them to the gate of the MOSFET. The gate drive resistor Rg is used to adjust the drive current intensity, and the gate discharge resistor Rgsl is used to ensure that the gate is at a low level when there is no drive signal.

Further, when the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both high level, the half-bridge drive chip controls the high-side MOSFET chip QH and the low-side MOSFET chip QL to turn on, and the fuel injector drive current I is powered from the power supply. The terminal Vbst passes through the high-side MOSFET chip QH, the injector Injector, the current sampling resistor Rs, and the low-side MOSFET chip QL to the power ground PGND in turn to realize the drive of the fuel injector;

When the fuel injection signal Drive of the input power drive unit is high and the logic signal Logical Drive is low, the high-side MOSFET chip QH is turned off, and the low-side MOSFET chip QL is turned on. At this time, the freewheeling mode is entered, and the current flows from the power ground PGND. Pass through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the low-side MOSFET chip QL in turn to the power ground PGND, until the fuel injector drive current drops to 0; at this time, both ends of the freewheeling loop are the power ground PGND , the electromotive force is equal, so the downward trend of the driving current is more moderate, which can reduce the modulation frequency of the logic control unit;

When the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both low level, the half-bridge driver chip controls the high-side MOSFET chip QH and the low-side MOSFET chip QL to turn off, and then enters the freewheeling mode, and the current flows from the power ground. PGND goes through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the freewheeling diode D2 to the power supply terminal Vbst in turn, until the driving current of the injector drops to 0, and the input terminal of the freewheeling circuit is the power ground PGND, and the output terminal For the power supply terminal Vbst, the driving current drops rapidly in the process of charging the power supply terminal Vbst, which can accelerate the closing process of the fuel injector, recover part of the energy and reduce heat generation.

In the above power drive unit, the logic signal Logical Drive realizes peak-hold current drive by controlling the switch of the high-side MOSFET chip QH, that is, the high-side modulation; similarly, the logic signal controls the switch of the low-side MOSFET chip QL, that is Low-side modulation can also achieve peak-hold current drive. However, considering the charging and discharging process of the bootstrap capacitor, it is recommended to use a high-side modulation method.

The above-mentioned power drive unit adopts a half-bridge drive circuit, and can also use a single low-side drive or a dual power supply drive. The single low-side drive only needs to input the logic signal Logical Drive, but it cannot apply the variable freewheeling scheme of the above-mentioned half-bridge circuit, resulting in problems such as the slow closing process of the injector and the increased thermal load of the freewheeling circuit; the advantages of dual power drive are: In the holding current stage, the low-voltage power supply is used to drive to save power, but the driving current waveform is basically the same as that of the above-mentioned single-power-supplyed half-bridge drive circuit, and a high-side drive chip and a MOSFET chip are added. Therefore, the above-mentioned power drive unit using a single power supply half-bridge drive circuit is the simplest power drive unit to ensure the drive effect.

Further, the fault diagnosis process of the microcontroller includes the following steps:

；喷油信号Drive起始时刻至第一路比较器信号C1上升沿时刻的时间间隔，即为电流上升至峰值所用时间

；第一路比较器信号C1上升沿时刻至第二路比较器信号C2下降沿时刻的时间间隔，即为电流由峰值电流向保持电流过渡所用时间

；Step (1), before the microcontroller outputs the fuel injection signal Drive, first enable the input capture function of the two comparator signals in the current detection unit. With the output of the fuel injection signal Drive, the two input captures detect the second channel successively. The rising edge of the comparator signal C2, the rising edge of the first comparator signal C1, and the falling edge of the second comparator signal C2, and record the corresponding time at the same time; wherein, the fuel injection signal Drive start time to the second comparator The time interval between the rising edge of signal C2, that is, the time it takes for the current to rise to the holding value

; The time interval from the start of the fuel injection signal Drive to the rising edge of the first comparator signal C1 is the time it takes for the current to rise to the peak value

; The time interval from the rising edge of the first comparator signal C1 to the falling edge of the second comparator signal C2 is the time it takes for the current to transition from the peak current to the holding current

;

、

、

均为固定值，通过预标定的方式将

、

和

记录在微控制器中；Step (2) Entering the current holding stage, in order to avoid the frequent switching of the high and low levels of the second comparator signal C2 in the current holding stage to occupy the resources of the microcontroller, temporarily turn off the input capture function of the two comparator signals until Before the microcontroller outputs the fuel injection signal Drive next time, the input capture function of the two comparator signals is enabled again; under the fixed driving voltage Vbst, due to the stable internal resistance and inductance characteristics of the fuel injector,

,

,

are fixed values, and the pre-calibration method will

,

and

recorded in the microcontroller;

、

、

与标定值对比，判断当前峰值-保持驱动电路及喷油器的状态，具体的判断逻辑如下：Then the microcontroller detects the level signals of the two comparators and the

,

,

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows:

、

、

与标定值差异在10%以内，则判定峰值-保持驱动电路及喷油器正常；Step (2-1) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected successively, and the obtained time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal;

标定值两倍以上时，则判定喷油器或者MOSFET芯片QH、QL三者中至少有一个断路；Step (2-2) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the fuel injector or MOSFET chips QH and QL is open circuit;

、

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到第一路比较器信号C1和第二路比较器信号C2的低电平，则判定喷油器短路，峰值-保持驱动电路正常；如果长期未检测到第一路比较器信号C1和第二路比较器信号C2的低电平，则判断喷油器及高侧MOSFET芯片QH和低侧MOSFET芯片QL均短路；Step (2-3) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 is detected, but the time parameter

,

is much smaller than the calibration value, and the microcontroller quickly turns off the fuel injection signal Drive. If the low level of the first comparator signal C1 and the second comparator signal C2 is detected subsequently, it is determined that the fuel injector is short-circuited, and the peak value - Keep the drive circuit normal; if the low level of the first comparator signal C1 and the second comparator signal C2 is not detected for a long time, it is judged that the fuel injector and the high-side MOSFET chip QH and the low-side MOSFET chip QL are short-circuited;

、

与标定值差异在10%以内，但在随后两倍的

时间内仍未能检测到第二路比较器信号C2的低电平，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常；Step (2-4) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected, and the acquired time parameter

,

within 10% of the nominal value, but after twice the

The low level of the second comparator signal C2 cannot be detected within the time, and the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal;

、

与标定值差异在10%以内，但

低于标定值的90%，则判定续流二极管D1断路。Step (2-5) During the driving process, if the high level of the first comparator signal C1, the second comparator signal C2 and the low level of the second comparator signal C2 are sequentially detected, and the acquired time parameter

,

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is judged that the freewheeling diode D1 is disconnected.

Further, if the microcontroller includes a high-speed analog-to-digital conversion module, fault diagnosis is performed through the current signal Current. At this time, the process of the microcontroller performing fault diagnosis is as follows:

，峰值电流时刻至之后首次到达保持电流时刻即为

，喷油信号Drive关闭后至驱动电流降低为0的时刻即为

；Step (A), start recording the driving current value in real time when the microcontroller outputs the fuel injection signal Drive, mark the moment when the driving current reaches the peak current, the moment when the driving current reaches the holding current for the first time after reaching the peak current, and the microcontroller The moment when the drive current decreases to 0 after the output fuel injection signal Drive is turned off; among them, the starting time of the fuel injection signal Drive to the peak current moment is

, the peak current time to the first time the holding current is reached after that is

, the moment when the fuel injection signal Drive is turned off to when the drive current is reduced to 0 is

;

、

、

均为固定值，并通过预标定的方式将

、

和

记录在微控制器中；in,

,

,

are fixed values, and are pre-calibrated to

,

and

recorded in the microcontroller;

、

和

与标定值对比，判断当前峰值-保持驱动电路及喷油器的状态，具体的判断逻辑如下：Step (B), the current waveform detected by the microcontroller according to each fuel injection process and

,

and

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows:

、

、

与标定值差异在10%以内，则判定峰值-保持驱动电路及喷油器正常；Step (B1), in the driving process, if the standard current waveform is detected, and the time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal;

标定值两倍以上时，判定喷油器、高侧MOSFET芯片QH和低侧MOSFET芯片QL三者中至少有一个断路；Step (B2), in the driving process, if the standard current waveform cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the injector, the high-side MOSFET chip QH and the low-side MOSFET chip QL is disconnected;

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到电流下降，则判定喷油器短路，峰值-保持驱动电路正常；如果随后检测到电流持续超过峰值电流，则喷油器、高侧MOSFET芯片QH和低侧MOSFET芯片QL均短路；In step (B3), during the driving process, it is detected that the current exceeds the set peak current by more than 20%, and

Much smaller than the calibration value, the microcontroller quickly turns off the fuel injection signal Drive. If the current drop is detected later, it is determined that the fuel injector is short-circuited, and the peak-keep drive circuit is normal; if the current continues to exceed the peak current, the injection The oil tank, the high-side MOSFET chip QH and the low-side MOSFET chip QL are all short-circuited;

与标定值差异在10%以内，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常；Step (B4), during the driving process, it is detected that the current continues to rise and exceeds the peak value, but the time parameter

The difference from the calibration value is within 10%. At this time, the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal;

与标定值差异在10%以内，但

低于标定值的90%，则判定续流二极管D1断路；Step (B5), in the driving process, after detecting that the current reaches the peak value, it transitions to the hold value, and the time parameter

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is determined that the freewheeling diode D1 is open circuit;

、

与标定值差异在10%以内，但

大于标定值两倍以上时，判定低侧MOSFET芯片QL短路或续流二极管D2断路，喷油器正常。Step (B6), during the driving process, the standard current waveform is detected, and the time parameter

,

The difference from the calibration value is within 10%, but

When it is more than twice the calibration value, it is determined that the low-side MOSFET chip QL is short-circuited or the freewheeling diode D2 is open-circuited, and the injector is normal.

The invention also discloses an unmanned aerial vehicle engine, comprising a direct injection fuel injector, the coil of the direct injection fuel injector is connected to a peak-hold driving circuit with fault diagnosis protection.

Beneficial effect: Compared with the prior art, the present invention has the following advantages:

(1) The present invention adopts a current sense amplifier with dual comparators, and cooperates with a configurable multi-function gate to realize a peak-hold current-driven control circuit with a minimum number of chips and a minimum component area, simplifying the hardware of the electronic control unit. and software complexity, and provides complete fault diagnosis protection.

(2) The present invention can provide two fault diagnosis methods according to the performance of the microcontroller, the first one is simple in program, and the second one has comprehensive functions, which can be flexibly used according to the application.

(3) The logic signal in the power drive unit of the present invention realizes the peak-hold current drive by controlling the switch of the high-side MOSFET chip, that is, the high-side modulation; the logic signal can also control the switch of the low-side MOSFET chip, that is, the low-side MOSFET chip. side modulation for peak-hold current drive.

(4) In addition to the half-bridge driving circuit, the present invention can also be applied to a single low-side driving circuit or a dual power supply driving circuit, and can also realize peak-hold driving with fault diagnosis protection.

(5) The latch function included in the current detection unit of the present invention enables the first comparator output signal C1 to be maintained after it becomes a high level within a single fuel injection signal cycle, thereby ensuring the peak-hold current driving process Only a single peak current waveform is output.

Description of drawings

Fig. 1 is the overall frame diagram of the peak-hold driving circuit of the present invention;

2 is a schematic diagram of a power drive unit circuit in the present invention;

3 is a schematic diagram of a circuit of a current detection unit in the present invention;

4 is a schematic diagram of a logic control unit circuit in the present invention;

5 is a schematic diagram of a microcontroller unit circuit in the present invention;

6 is a schematic diagram of the variation of driving current with time in the embodiment;

7 is a schematic diagram of driving current in Embodiment 1;

FIG. 8 is a schematic diagram of driving current in Example 2. FIG.

Detailed ways

The technical solutions of the present invention are described in detail below, but the protection scope of the present invention is not limited to the embodiments.

As shown in FIG. 1 , a peak-hold driving circuit with fault diagnosis protection in this embodiment includes a microcontroller, a power driving unit, a current detection unit and a logic control unit, and the current detection unit and the logic control unit constitute a control circuit ; The current detection unit adopts a current sense amplifier with a dual comparator, which receives the voltage signals Rs+ and Rs- at both ends of the current sampling resistor in the power drive unit and receives the fuel injection signal Drive of the microcontroller, and then the first comparator Latch control, and then output the first comparator signal C1 and the second comparator signal C2 according to the current signal Current and the latch control signal, and output to the logic control unit after being pulled up by the resistor Rpu1 and the resistor Rpu2; micro control The controller is integrated in the electronic control unit ECU, the microcontroller outputs the fuel injection signal Drive and receives the two-way comparator signal and current signal Current fed back by the current detection unit to realize fault diagnosis; the logic control unit is based on the fuel injection signal Drive and The first comparator signal C1 and the second comparator signal C2 of the current detection unit output the logic signal Logical Drive; the power drive unit receives the logic signal Logical Drive of the logic control unit and the fuel injection signal Drive of the microcontroller as high respectively. Side drive input and low-side drive input, the output drive signal drives the high-side MOSFET chip QH and the low-side MOSFET chip QL respectively. One end of the high-side MOSFET chip QH is connected to the power supply, one end of the low-side MOSFET chip QL is connected to the power ground, and the high-side MOSFET chip is connected to the power ground. The current sampling resistor Rs and the connector of the injector are connected between QH and the low-side MOSFET chip QL in turn, so as to control the opening and closing of the drive circuit.

与功率驱动电流

以及电流采样电阻

的关系满足：As shown in Figure 3, the current detection unit also includes two RC filter circuits composed of filter resistors Rf+ and Rf- and filter capacitor Cf. Input current sense amplifier. In this embodiment, the current sense amplifier adopts INA203, and its magnification is 20V/V, then the output voltage of the current sense amplifier

with power drive current

and current-sampling resistors

The relationship satisfies:

；

;

直接接入第一路比较器，同时经过分压电阻

和分压电阻

分压后接入第二路比较器，则使得两路比较器输出两路高电平信号的最小驱动电流

和

分别为：The current sense amplifier INA203 integrates two comparator output voltages

Directly connect to the first comparator, and pass through the voltage divider resistor at the same time

and divider resistor

After dividing the voltage, the second comparator is connected, so that the two comparators output the minimum driving current of the two high-level signals

and

They are:

；

;

；

;

以及分压电阻

和分压电阻

，来使得峰值电流为

且保持电流为

；此时电流检测放大器在驱动电流高于峰值电流和保持电流时分别输出高电平的第一路比较器信号C1和第二路比较器信号C2，接着经过电阻Rpu1和电阻Rpu2上拉后输出给逻辑控制单元。Then control the current sampling resistor

and divider resistors

and divider resistor

, so that the peak current is

and the holding current is

; At this time, the current detection amplifier outputs the first comparator signal C1 and the second comparator signal C2 of high level respectively when the driving current is higher than the peak current and the holding current, and then outputs after being pulled up by the resistor Rpu1 and the resistor Rpu2 to the logic control unit.

后，第一路比较器信号C1变为高电平且被锁存，使得驱动电流I低于峰值电流

，第一路比较器信号C1维持高电平，直至喷油信号Drive变为低电平使得锁存器复位。The latch integrated on the first comparator in this embodiment is controlled by the fuel injection signal Drive. When the fuel injection signal Drive is at a low level, the latch is reset. At this time, the level of the first comparator signal C1 is only It is related to the drive current I; when the fuel injection signal is at a high level, the latch works, that is, the drive current I reaches the peak current

After that, the first comparator signal C1 becomes high level and is latched, so that the driving current I is lower than the peak current

, the first comparator signal C1 maintains a high level until the fuel injection signal Drive becomes a low level to reset the latch.

As shown in FIG. 4 , the logic control unit of this embodiment is configured with a multi-function logic gate, and the multi-function logic gate receives the fuel injection signal Drive of the micro-control and the first comparator signal C1 and the second comparator of the current detection unit Signal C2, and outputs the logic signal Logical Drive; the multi-function logic gate is provided with In0 channel, In1 channel and In2 channel, the logic control unit changes the level of the output signal Y according to the levels of the input signals of the three channels In0, In1 and In2 , and then input the fuel injection signal Drive into the In0 channel, the second comparator signal C2 into the In1 channel, the first comparator signal C1 into the In2 channel, and the output signal Y is the logic signal Logical Drive.

The truth value of the logic gate of this embodiment is shown in Table 1, where L represents a low level and H represents a high level.

Table 1

In0 In1 In2 Y L L L L L L H H L H L L L H H L H L L H H L H H H H L H H H H L

In a single complete peak-hold driving cycle, the driving current and the input signal of the logic control unit vary with time as shown in Table 2 and Figure 6.

Table 2

time T0 T1 T2 T3 T4 T4-T5 T5 T6 Drive(In0) L H H H H H L L C2(In1) L L H H L H/L H/L L C1(In2) L L L H H H L L Logical Drive(Y) L H H L H L/H L L

In Figure 6, at time T1, the drive signal Drive changes from low to high, the logic signal Logical Drive also changes from low to high, and the drive injector current continues to rise; at time T2, the drive current reaches the holding current, and the second comparator signal C2 is set by From low to high, the logic signal Logical Drive maintains a high level; at time T3, the drive current rises to the peak current, the first comparator signal C1 changes from low to high, at this time the logic signal Logical Drive changes from high to low, the drive current drops and It transitions to the holding current, after which the first comparator signal C1 is latched by the drive signal Drive to maintain a high level signal; the drive current drops below the holding current at T4, the second comparator signal C2 changes from high to low, and the logic The signal Logical Drive changes from low to high; before time T5, the logic signal Logical Drive and the second comparator signal C2 have opposite trends, so that the drive current fluctuates and stabilizes at the holding current; at time T5, the drive signal Drive changes from high to low , the latch is reset, the first comparator signal C1 becomes low level, at this time no matter the level state of the second comparator signal C2, the output signal Logical Drive of the logic control unit is low level, and the output drive is turned off The current drops to 0 until time T6. In short, in Figure 6, the current reaches the peak value after the output drive, and drops to a constant value after the current is maintained until the turn-off drive current drops to 0, forming a standard current waveform as a whole. So far, a complete peak-hold driving process is completed.

As shown in FIG. 2 , the power drive unit of this embodiment adopts a half-bridge drive circuit, including a half-bridge drive chip and a bootstrap capacitor Cboot. The half-bridge drive chip inputs the logic signals Logical Drive and spray through the HI pin and the LI pin respectively. The oil signal Drive, and then the half-bridge driver chip outputs the drive signal through the HO pin and the LO pin respectively. The drive signal is input to the gate of the high-side MOSFET chip QH through the gate drive resistor Rgh through the HO pin, and the LO lead is used to output the drive signal. The pin inputs the drive signal to the gate of the low-side MOSFET chip QL through the gate drive resistor Rgl, and then drives the high-side MOSFET chip QH and the low-side MOSFET chip QL; the drain of the high-side MOSFET chip QH is connected to the power supply Vbst, and the source is connected to The current sampling resistor Rs is also connected to the power ground PGND through the Schottky diode D1 to form a freewheeling loop; the source of the low-side MOSFET chip QL is connected to the power ground PGND, the drain is connected to the injector, and the Schottky diode D2 is also connected to the power ground PGND. Connect the power supply Vbst to form a freewheeling loop. When the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both high level, the half-bridge driver chip controls the high-side MOSFET chip QH and the low-side MOSFET chip QL to turn on, and the current flows from the power supply terminal Vbst through the high-side MOSFET chip in turn. Chip QH, injector Injector, current sampling resistor Rs, low-side MOSFET chip QL to power ground PGND to drive the injector;

When the fuel injection signal Drive of the input power drive unit is high and the logic signal Logical Drive is low, the high-side MOSFET chip QH is turned off, and the low-side MOSFET chip QL is turned on. At this time, the freewheeling mode is entered, and the current flows from the power ground PGND. Pass through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the low-side MOSFET chip QL in turn to the power ground PGND, until the fuel injector drive current drops to 0; at this time, both ends of the freewheeling loop are the power ground PGND , the electromotive force is equal;

When the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both low level, the half-bridge driver chip controls the high-side MOSFET chip QH and the low-side MOSFET chip QL to turn off, and then enters the freewheeling mode, and the current flows from the power ground. PGND goes through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the freewheeling diode D2 to the power supply terminal Vbst in turn, until the driving current of the injector drops to 0, and the input terminal of the freewheeling circuit is the power ground PGND, and the output terminal It is the power supply terminal Vbst.

As shown in FIG. 5 , the microcontroller of this embodiment can use any microcontroller that includes the two basic functions of output control and input capture. It outputs the fuel injection signal Drive and receives the first path of the current detection amplifier INA203. The comparator signal C1 and the second comparator signal C2. If the microcontroller includes a high-speed analog-to-digital conversion function, it can receive the current signal Current output by the current detection amplifier INA203 and perform fault diagnosis and protection based on this signal. Because the fault diagnosis strategy involved in the present invention occupies less resources of the microcontroller and has low performance requirements, the microcontroller can be used as a drive control and fault diagnosis sub-module and integrated in the electronic control unit of the UAV engine. Here, the UAV engine electronic control unit calculates the engine work according to a series of engine state and environmental state parameters such as the current engine throttle opening, engine speed, engine operating conditions, ambient temperature, cylinder head temperature, exhaust temperature, and fuel temperature. The required fuel injection phase and injection duration, that is, the timing and pulse width of the output fuel injection signal Drive.

A fault diagnosis method for a peak-hold driving circuit in this embodiment includes the following steps:

；喷油信号Drive起始时刻至第一路比较器信号C1上升沿时刻的时间间隔，即为电流上升至峰值所用时间

；第一路比较器信号C1上升沿时刻至第二路比较器信号C2下降沿时刻的时间间隔，即为电流由峰值电流向保持电流过渡所用时间

；Step (1), before the microcontroller outputs the fuel injection signal Drive, first enable the input capture function of the two comparator signals in the current detection unit. With the output of the fuel injection signal Drive, the two input captures detect the second channel successively. The rising edge of the comparator signal C2, the rising edge of the first comparator signal C1, and the falling edge of the second comparator signal C2, and record the corresponding time at the same time; wherein, the fuel injection signal Drive start time to the second comparator The time interval between the rising edge of signal C2, that is, the time it takes for the current to rise to the holding value

; The time interval from the start of the fuel injection signal Drive to the rising edge of the first comparator signal C1 is the time it takes for the current to rise to the peak value

; The time interval from the rising edge of the first comparator signal C1 to the falling edge of the second comparator signal C2 is the time it takes for the current to transition from the peak current to the holding current

;

、

、

均为固定值，通过预标定的方式将

、

和

记录在微控制器中；Step (2) Enter the current holding stage, temporarily turn off the input capture function of the two comparator signals, and enable the input capture function of the two comparator signals again until the next time the microcontroller outputs the fuel injection signal Drive; under the driving voltage Vbst

,

,

are fixed values, and the pre-calibration method will

,

and

recorded in the microcontroller;

、

、

与标定值对比，判断当前峰值-保持驱动电路及喷油器的状态，具体的判断逻辑如下：Then the microcontroller detects the level signals of the two comparators and the

,

,

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows:

、

、

与标定值差异在10%以内，则判定峰值-保持驱动电路及喷油器正常；Step (2-1) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected successively, and the obtained time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal;

标定值两倍以上时，则判定喷油器或者MOSFET芯片QH、QL三者中至少有一个断路；Step (2-2) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the fuel injector or MOSFET chips QH and QL is open circuit;

、

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到第一路比较器信号C1和第二路比较器信号C2的低电平，则判定喷油器短路，峰值-保持驱动电路正常；如果长期未检测到第一路比较器信号C1和第二路比较器信号C2的低电平，则判断喷油器及高侧MOSFET芯片QH和低侧MOSFET芯片QL均短路；Step (2-3) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 is detected, but the time parameter

,

is much smaller than the calibration value, and the microcontroller quickly turns off the fuel injection signal Drive. If the low level of the first comparator signal C1 and the second comparator signal C2 is detected subsequently, it is determined that the fuel injector is short-circuited, and the peak value - Keep the drive circuit normal; if the low level of the first comparator signal C1 and the second comparator signal C2 is not detected for a long time, it is judged that the fuel injector and the high-side MOSFET chip QH and the low-side MOSFET chip QL are short-circuited;

、

与标定值差异在10%以内，但在随后两倍的

时间内仍未能检测到第二路比较器信号C2的低电平，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常；Step (2-4) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected, and the acquired time parameter

,

within 10% of the nominal value, but after twice the

The low level of the second comparator signal C2 cannot be detected within the time, and the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal;

、

与标定值差异在10%以内，但

低于标定值的90%，则判定续流二极管D1断路。Step (2-5) During the driving process, if the high level of the first comparator signal C1, the second comparator signal C2 and the low level of the second comparator signal C2 are sequentially detected, and the acquired time parameter

,

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is judged that the freewheeling diode D1 is disconnected.

If the microcontroller of this embodiment includes a high-speed analog-to-digital conversion module, the fault diagnosis can be performed through the current signal Current. At this time, the fault diagnosis method of the peak-hold driving circuit is as follows:

，峰值电流时刻至之后首次到达保持电流时刻即为

，喷油信号Drive关闭后至驱动电流降低为0的时刻即为

；Step (A), start recording the driving current value in real time when the microcontroller outputs the fuel injection signal Drive, mark the moment when the driving current reaches the peak current, the moment when the driving current reaches the holding current for the first time after reaching the peak current, and the microcontroller The moment when the drive current decreases to 0 after the output fuel injection signal Drive is turned off; among them, the starting time of the fuel injection signal Drive to the peak current moment is

, the peak current time to the first time the holding current is reached after that is

, the moment when the fuel injection signal Drive is turned off to when the drive current is reduced to 0 is

;

、

、

均为固定值，并通过预标定的方式将

、

和

记录在微控制器中；in,

,

,

are fixed values, and are pre-calibrated to

,

and

recorded in the microcontroller;

、

和

与标定值对比，判断当前峰值-保持驱动电路及喷油器的状态，具体的判断逻辑如下：Step (B), the current waveform detected by the microcontroller according to each fuel injection process and

,

and

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows:

、

、

与标定值差异在10%以内，则判定峰值-保持驱动电路及喷油器正常；Step (B1), in the driving process, if a standard current waveform (as shown in Figure 6) is detected, and the time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal;

标定值两倍以上时，判定喷油器、高侧MOSFET芯片QH和低侧MOSFET芯片QL三者中至少有一个断路；Step (B2), in the driving process, if the standard current waveform cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the injector, the high-side MOSFET chip QH and the low-side MOSFET chip QL is disconnected;

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到电流下降，则判定喷油器短路，峰值-保持驱动电路正常；如果随后检测到电流持续超过峰值电流，则喷油器、高侧MOSFET芯片QH和低侧MOSFET芯片QL均短路；In step (B3), during the driving process, it is detected that the current exceeds the set peak current by more than 20%, and

Much smaller than the calibration value, the microcontroller quickly turns off the fuel injection signal Drive. If the current drop is detected later, it is determined that the fuel injector is short-circuited, and the peak-keep drive circuit is normal; if the current continues to exceed the peak current, the injection The oil tank, the high-side MOSFET chip QH and the low-side MOSFET chip QL are all short-circuited;

与标定值差异在10%以内，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常；Step (B4), during the driving process, it is detected that the current continues to rise and exceeds the peak value, but the time parameter

The difference from the calibration value is within 10%. At this time, the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal;

与标定值差异在10%以内，但

低于标定值的90%，则判定续流二极管D1断路；Step (B5), in the driving process, after detecting that the current reaches the peak value, it transitions to the holding value, and the time parameter

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is determined that the freewheeling diode D1 is open circuit;

、

与标定值差异在10%以内，但

大于标定值两倍以上时，判定低侧MOSFET芯片QL短路或续流二极管D2断路，喷油器正常。Step (B6), during the driving process, the standard current waveform is detected, and the time parameter

,

The difference from the calibration value is within 10%, but

When it is more than twice the calibration value, it is determined that the low-side MOSFET chip QL is short-circuited or the freewheeling diode D2 is open-circuited, and the injector is normal.

An unmanned aerial vehicle engine of this embodiment includes a direct injection fuel injector, and the coil of the direct injection fuel injector is connected to the above-mentioned peak-hold driving circuit with fault diagnosis protection.

Example 1:

The peak-hold driving circuit of this embodiment is applied to a direct injection fuel injector, and its fault diagnosis and protection are performed. The specific contents are:

为5mΩ，分压电阻

为0Ω，

不焊接即可，具体驱动电流见图7。First, calibrate the internal resistance of the direct injection injector as 2.70Ω, the inductance as 2.55mH, and the threshold current as 5A; then set the hold current as 6A and the peak current as 12A. According to the aforementioned formula, the precision current sampling resistor

5mΩ, divider resistor

is 0Ω,

No welding is required. The specific driving current is shown in Figure 7.

、

、

均与标定值差异在10%以内，则判定峰值-保持驱动电路及喷油器正常。During the driving process, if the high level of the two comparator signals can be detected successively, and the obtained time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and the injector are normal.

标定值两倍以上时，则判定喷油器或者MOSFET芯片QH、QL三者中至少有一个断路。During the driving process, if the high level of the two comparator signals cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the fuel injector or MOSFET chips QH and QL is open circuit.

、

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到两路比较器信号的低电平，则判定喷油器短路，峰值-保持驱动电路正常；如果长期未检测到两路比较器信号的低电平，则喷油器及MOSFET芯片QH、QL均短路。During the driving process, if the high level of the two comparator signals is detected, the time parameter

,

Much smaller than the calibration value, at this time, the microcontroller quickly turns off the fuel injection signal Drive. If the low level of the two comparator signals is detected subsequently, it is determined that the fuel injector is short-circuited, and the peak-hold drive circuit is normal; if it is not detected for a long time. The low level of the two comparator signals will short-circuit the injector and the MOSFET chips QH and QL.

、

，与标定值差异在10%以内，但在随后两倍的

仍未能检测到第二比较器信号的低电平，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常。During the driving process, if the high level of the two comparator signals is detected, the obtained time parameter

,

, within 10% of the nominal value, but after twice the

The low level of the second comparator signal is still not detected. At this time, the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited and the fuel injector is normal.

、

与标定值差异在10%以内，但

低于标定值的90%，则判定续流二极管D1断路。During the driving process, if the high level of the first comparator signal C1, the high level of the second comparator signal C2 and the low level of the second comparator signal C2 are sequentially detected, the obtained time parameter

,

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is judged that the freewheeling diode D1 is disconnected.

Example 2:

This embodiment simplifies the peak-hold drive into a hold drive, that is, constant current drive, which is applied to a direct injection fuel injector, and performs fault diagnosis and protection on it. The specific contents are:

为6mΩ，分压电阻

与

阻值相同即可，具体驱动电流见图8。First, calibrate the internal resistance of the injector to 2.70Ω, the inductance to 2.55mH, and the target drive current to be 10A; then set the peak current and hold current to be 10A, and the precision current sampling resistor

6mΩ, divider resistor

and

The resistance value is the same, and the specific driving current is shown in Figure 8.

、

与标定值差异在10%以内，则判定恒流驱动电路及喷油器正常。During the driving process, if the high level of the first comparator signal C1 and the high level of the second comparator signal C2 can be detected at the same time, and the obtained time parameter

,

If the difference from the calibration value is within 10%, it is judged that the constant current drive circuit and the fuel injector are normal.

标定值两倍以上时，则判定喷油器或者MOSFET芯片QH、QL三者中至少有一个断路。During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the fuel injector or MOSFET chips QH and QL is open circuit.

、

远小于标定值，此时微控制器迅速关闭喷油信号Drive，如果随后检测到第一路比较器信号C1的低电平和第二路比较器信C2的低电平，则判定喷油器短路，恒流驱动电路正常；如果长期未检测到第一路比较器信号C1的低电平和第二路比较器信C2的低电平，则喷油器及MOSFET芯片QH、QL均短路。During the driving process, if the high level of the first comparator signal C1 and the high level of the second comparator signal C2 are detected, but the time parameter

,

It is much smaller than the calibration value. At this time, the microcontroller quickly turns off the fuel injection signal Drive. If the low level of the first comparator signal C1 and the low level of the second comparator signal C2 are then detected, it is determined that the injector is short-circuited. , the constant current drive circuit is normal; if the low level of the first comparator signal C1 and the low level of the second comparator signal C2 are not detected for a long time, the injector and the MOSFET chips QH and QL are short-circuited.

、

均与标定值差异在10%以内，但在随后

时间内未能检测到第二路比较器信号C2的低电平，此时微控制器迅速关闭喷油信号Drive，并判定高侧MOSFET芯片QH短路，喷油器正常。During the driving process, if the low level of the first comparator signal C1 and the low level of the second comparator signal C2 can be detected, the obtained time parameter

,

are within 10% of the calibration value, but after

The low level of the second comparator signal C2 cannot be detected within the time. At this time, the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited and the fuel injector is normal.

Claims (8)

1. a peak-hold drive circuit with fault diagnosis protection, characterized in that: comprising a microcontroller, a power drive unit, a current detection unit and a logic control unit, the current detection unit and the logic control unit constitute a control circuit; The current detection unit adopts a current sense amplifier with a two-way comparator, which receives the voltage signals Rs+ and Rs- at both ends of the current sampling resistor in the power drive unit and receives the fuel injection signal Drive of the microcontroller, and then compares the first path. and then output the first comparator signal C1 and the second comparator signal C2 according to the current signal Current and the latch control signal, and output to the logic control unit after being pulled up by the resistor Rpu1 and the resistor Rpu2; The microcontroller is integrated in the electronic control unit ECU, and the microcontroller outputs the fuel injection signal Drive and receives the first comparator signal C1, the second comparator signal C2 and the current signal Current fed back by the current detection unit to realize fault diagnosis. ; The logic control unit outputs the logic signal Logical Drive according to the fuel injection signal Drive of the microcontroller and the first comparator signal C1 and the second comparator signal C2 of the current detection unit; The power drive unit receives the logic signal Logical Drive of the logic control unit and the fuel injection signal Drive of the microcontroller as the high-side drive input and the low-side drive input, respectively, and the output drive signal drives the high-side MOSFET chip QH and the low-side MOSFET respectively. Chip QL, one end of the high-side MOSFET chip QH is connected to the power supply, and one end of the low-side MOSFET chip QL is connected to the power ground. plug-in, and then control the opening and closing of the drive circuit; the current detection unit also includes two RC filter circuits composed of filter resistors Rf+ and Rf- and filter capacitor Cf, through the two RC filter circuits The voltage signal Rs+ and the voltage signal Rs- are input to the current sense amplifier, and the magnification of the current sense amplifier is G(V/V), then the output voltage of the current sense amplifier

with power drive current

and current-sampling resistors

The relationship satisfies:

; The current sense amplifier is internally integrated with two comparator output voltages

Directly connect to the first comparator, and pass through the voltage divider resistor at the same time

and divider resistor

After dividing the voltage, the second comparator is connected, so that the two comparators output the minimum driving current of the high-level signal

and

They are:

;

; Then control the current sampling resistor

and divider resistors

and divider resistor

, so that the peak current is

and the holding current is

; At this time, the current detection amplifier outputs the first comparator signal C1 and the second comparator signal C2 of high level respectively when the driving current I is higher than the peak current and the holding current, and then pulls up through the resistor Rpu1 and the resistor Rpu2. output to the logic control unit. 2. The peak-hold driving circuit with fault diagnosis protection according to claim 1, wherein the specific content of the first-path comparator latch control is: the integrated latch on the first-path comparator is composed of The fuel injection signal Drive is controlled. When the fuel injection signal Drive is at a low level, the latch is reset. At this time, the level of the first comparator signal C1 is only related to the drive current I; when the fuel injection signal is at a high level, the latch is reset. The memory works, that is, the drive current I reaches the peak current

After that, the first comparator signal C1 becomes high level and is latched, so that the driving current I is lower than the peak current

, the first comparator signal C1 maintains a high level until the fuel injection signal Drive becomes a low level to reset the latch. 3. The peak-hold drive circuit with fault diagnosis protection according to claim 1, wherein the logic control unit is configured with a multi-function logic gate, and the multi-function logic gate receives the micro-controlled fuel injection signal Drive and current The first comparator signal C1 and the second comparator signal C2 of the detection unit, and output the logic signal Logical Drive; the multi-function logic gate is provided with In0 channel, In1 channel and In2 channel, the logic control unit is based on In0, In1, The level of the input signals of the three channels of In2 changes the level of the output signal Y, the fuel injection signal Drive is input to the In0 channel, the second comparator signal C2 is input to the In1 channel, and the first comparator signal C1 is input to the In2 channel, then the output signal Y is the logical signal LogicalDrive. 4 . The peak-hold driving circuit with fault diagnosis protection according to claim 1 , wherein the power driving unit adopts a half-bridge driving circuit, including a half-bridge driving chip, and the half-bridge driving chips pass through the The HI pin and the LI pin input the logic signal Logical Drive and the fuel injection signal Drive, and then the half-bridge driver chip outputs the drive signal through the HO pin and the LO pin respectively; the drive signal is passed through the gate drive resistor through the HO pin. Rgh is input to the gate of the high-side MOSFET chip QH, and the drive signal is input to the gate of the low-side MOSFET chip QL through the gate drive resistor Rgl through the LO pin, thereby driving the high-side MOSFET chip QH and the low-side MOSFET chip QL; The drain of the high-side MOSFET chip QH is connected to the power supply Vbst, the source is connected to the current sampling resistor Rs, and the Schottky diode D1 is connected to the power ground PGND to form a freewheeling loop; the source of the low-side MOSFET chip QL is connected to the power ground. PGND, the drain is connected to the injector, and also connected to the power supply Vbst through the Schottky diode D2 to form a freewheeling loop. 5. The peak-hold drive circuit with fault diagnosis protection according to claim 4, wherein: when the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both high level, the half-bridge drive chip controls The high-side MOSFET chip QH and the low-side MOSFET chip QL are turned on, and the fuel injector drive current I goes through the high-side MOSFET chip QH, the fuel injector Injector, the current sampling resistor Rs, and the low-side MOSFET chip QL from the power supply terminal Vbst to the power ground PGND. , to realize the drive of the injector; When the fuel injection signal Drive of the input power drive unit is high and the logic signal Logical Drive is low, the high-side MOSFET chip QH is turned off, and the low-side MOSFET chip QL is turned on. At this time, the freewheeling mode is entered, and the current flows from the power ground PGND. Pass through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the low-side MOSFET chip QL in turn to the power ground PGND, until the fuel injector drive current drops to 0; at this time, both ends of the freewheeling loop are the power ground PGND , the electromotive force is equal; When the fuel injection signal Drive and the logic signal Logical Drive of the input power drive unit are both low level, the half-bridge driver chip controls the high-side MOSFET chip QH and the low-side MOSFET chip QL to turn off, and then enters the freewheeling mode, and the current flows from the power ground. PGND goes through the freewheeling diode D1, the injector Injector, the current sampling resistor Rs, and the freewheeling diode D2 to the power supply terminal Vbst in turn, until the driving current of the injector drops to 0, and the input terminal of the freewheeling circuit is the power ground PGND, and the output terminal It is the power supply terminal Vbst. 6. The peak-hold driving circuit with fault diagnosis protection according to claim 1, wherein the process of the fault diagnosis performed by the microcontroller comprises the following steps: Step (1), before the microcontroller outputs the fuel injection signal Drive, first enable the input capture function of the two comparator signals in the current detection unit. With the output of the fuel injection signal Drive, the two input captures detect the second channel successively. The rising edge of the comparator signal C2, the rising edge of the first comparator signal C1, and the falling edge of the second comparator signal C2, and record the corresponding time at the same time; wherein, the fuel injection signal Drive start time to the second comparator The time interval between the rising edge of signal C2, that is, the time it takes for the current to rise to the holding value

; The time interval from the start of the fuel injection signal Drive to the rising edge of the first comparator signal C1 is the time it takes for the current to rise to the peak value

; The time interval from the rising edge of the first comparator signal C1 to the falling edge of the second comparator signal C2 is the time it takes for the current to transition from the peak current to the holding current

; Step (2) Enter the current holding stage, temporarily turn off the input capture function of the two comparator signals, and enable the input capture function of the two comparator signals again until the next time the microcontroller outputs the fuel injection signal Drive; under the driving voltage Vbst

,

,

are fixed values, and the pre-calibration method will

,

and

recorded in the microcontroller; Then the microcontroller detects the level signals of the two comparators and the

,

,

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows: Step (2-1) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected successively, and the obtained time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal; Step (2-2) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the fuel injector or MOSFET chips QH and QL is open circuit; Step (2-3) During the driving process, if the high level of the first comparator signal C1 and the second comparator signal C2 is detected, but the time parameter

,

is much smaller than the calibration value, and the microcontroller quickly turns off the fuel injection signal Drive. If the low level of the first comparator signal C1 and the second comparator signal C2 is detected subsequently, it is determined that the fuel injector is short-circuited, and the peak value - Keep the drive circuit normal; if the low level of the first comparator signal C1 and the second comparator signal C2 is not detected for a long time, it is judged that the fuel injector and the high-side MOSFET chip QH and the low-side MOSFET chip QL are short-circuited; Step (2-4) During the driving process, if the high levels of the first comparator signal C1 and the second comparator signal C2 are detected, and the acquired time parameter

,

within 10% of the nominal value, but after twice the

The low level of the second comparator signal C2 cannot be detected within the time, and the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal; Step (2-5) During the driving process, if the high level of the first comparator signal C1, the second comparator signal C2 and the low level of the second comparator signal C2 are sequentially detected, and the acquired time parameter

,

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is judged that the freewheeling diode D1 is disconnected. 7. The peak-hold driving circuit with fault diagnosis protection according to claim 1, wherein if the microcontroller comprises a high-speed analog-to-digital conversion module, fault diagnosis is carried out by the current signal Current, and the microcontroller carries out The troubleshooting process is as follows: Step (A), start recording the driving current value in real time when the microcontroller outputs the fuel injection signal Drive, mark the moment when the driving current reaches the peak current, the moment when the driving current reaches the holding current for the first time after reaching the peak current, and the microcontroller The moment when the drive current decreases to 0 after the output fuel injection signal Drive is turned off; among them, the starting time of the fuel injection signal Drive to the peak current moment is

, the peak current time to the first time the holding current is reached after that is

, the moment when the fuel injection signal Drive is turned off to when the drive current is reduced to 0 is

; in,

,

,

are fixed values, and are pre-calibrated to

,

and

recorded in the microcontroller; Step (B), the current waveform detected by the microcontroller according to each fuel injection process and

,

and

Compared with the calibration value, the current peak-hold drive circuit and the state of the fuel injector are judged. The specific judgment logic is as follows: Step (B1), in the driving process, if the standard current waveform is detected, and the time parameter

,

,

If the difference from the calibration value is within 10%, it is determined that the peak-hold drive circuit and injector are normal; Step (B2), in the driving process, if the standard current waveform cannot be detected, and the pulse width of the fuel injection signal Drive is greater than

When the calibration value is more than twice, it is determined that at least one of the injector, the high-side MOSFET chip QH and the low-side MOSFET chip QL is disconnected; In step (B3), during the driving process, it is detected that the current exceeds the set peak current by more than 20%, and

Much smaller than the calibration value, the microcontroller quickly turns off the fuel injection signal Drive. If the current drop is detected later, it is determined that the fuel injector is short-circuited, and the peak-keep drive circuit is normal; if the current continues to exceed the peak current, the injection The oil tank, the high-side MOSFET chip QH and the low-side MOSFET chip QL are all short-circuited; Step (B4), during the driving process, it is detected that the current continues to rise and exceeds the peak value, but the time parameter

The difference from the calibration value is within 10%. At this time, the microcontroller quickly turns off the fuel injection signal Drive, and determines that the high-side MOSFET chip QH is short-circuited, and the fuel injector is normal; Step (B5), in the driving process, after detecting that the current reaches the peak value, it transitions to the hold value, and the time parameter

The difference from the calibration value is within 10%, but

If it is lower than 90% of the calibration value, it is determined that the freewheeling diode D1 is open circuit; Step (B6), during the driving process, the standard current waveform is detected, and the time parameter

,

The difference from the calibration value is within 10%, but

When it is more than twice the calibration value, it is determined that the low-side MOSFET chip QL is short-circuited or the freewheeling diode D2 is open-circuited, and the injector is normal. 8. A drone engine, characterized in that: comprising a direct injection fuel injector, the coil of the direct injection fuel injector is connected to the peak-hold with fault diagnosis protection described in any one of claims 1 to 5 Drive circuit.

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