CN115875172B

CN115875172B - Inductance type double ignition system driving circuit of unmanned aerial vehicle engine

Info

Publication number: CN115875172B
Application number: CN202310198737.8A
Authority: CN
Inventors: 季昊成; 刘锐; 苏小平; 李晶; 翟步云
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2023-03-03
Filing date: 2023-03-03
Publication date: 2023-05-09
Anticipated expiration: 2043-03-03
Also published as: CN115875172A

Abstract

The invention discloses an inductive double-ignition system driving circuit of an unmanned aerial vehicle engine, wherein a power driving unit drives a corresponding ignition coil to complete ignition according to a driving signal output by a logic control unit, and a primary current signal of the ignition coil is fed back to a current detection unit; the current detection unit amplifies the difference value of the current signals and inputs the amplified difference value into two paths of comparators, the output states of the signals of the comparators are controlled according to the ignition signals and the mode selection signals and are respectively fed back to the logic control unit and the microcontroller, the microcontroller realizes self-detection and fault diagnosis of the ignition system according to the signals of the two paths of comparators, and the logic control unit determines a final driving signal according to the ignition signals of the microcontroller and the signals of the two paths of comparators. The invention uses the double ignition system to ensure the reliable combustion of the mixed gas in the cylinder; the ignition energy is adaptively adjusted, so that the electric energy consumption is reduced; the multi-ignition ensures cold start in a low-temperature environment, accelerates warm-up, ignites thinner mixed gas, and reduces fuel consumption and emission.

Description

Inductance type double ignition system driving circuit of unmanned aerial vehicle engine

Technical Field

The invention relates to an ignition system driving circuit, in particular to an inductive double-ignition system driving circuit of an unmanned aerial vehicle engine.

Background

The ignition system is a pacemaker of an unmanned aerial vehicle engine, and the pacemaker ignites the mixed gas in the cylinder at a specific moment so that the high-temperature high-pressure gas expands and pushes the piston to do work. The power driving and fault diagnosis module of the ignition system for the vehicle is mature under the limitation of emission regulations, and the main scheme is that the module is integrated on the top of an ignition coil, and an electronic control unit only outputs a control signal. The unmanned aerial vehicle is designed for improving effective load and pursuing light weight, and an ignition coil of the unmanned aerial vehicle is small in size, light in weight and not integrated with a power driving and fault diagnosis module; in order to achieve high reliability, the unmanned aerial vehicle generally adopts a double ignition system with two spark plugs per cylinder, which makes the power driving and fault diagnosis modules of the ignition system of the electronic control unit more complex, so that the electronic control units of most unmanned aerial vehicle engine manufacturers are only provided with the power driving modules of the ignition system and no fault diagnosis modules.

In order to ensure the safety of the storage, transportation and use processes, the special unmanned aerial vehicle adopts heavy oil fuel such as kerosene or light diesel oil to replace gasoline, and the heavy oil fuel is difficult to ignite in a low-temperature and low-pressure environment, so that the unmanned aerial vehicle is difficult to start and insufficient in combustion. The high-energy ignition technology and the multi-time ignition technology can improve the problem, but the high-energy ignition technology puts higher requirements on the reliability of the ignition system and accelerates the ablation of the spark plug, so that the self-adaptive ignition energy adjustment control is needed to reduce unnecessary ignition coil power consumption and heat, and the service life of the spark plug and even the whole ignition system is prolonged; the multiple ignition technique requires a high rate of rise of the ignition coil drive current and requires a high response rate control program implementation.

The spark ignition system of the existing special unmanned aerial vehicle is generally used for a gasoline engine, and the volatility of gasoline is good, so that the magnetizing pulse width is only required to be increased slightly under special working conditions such as lean combustion and the like, and the ignition energy is improved, so that the combustion process is improved, and the emission is reduced. For racing-grade gasoline engines (such as two-stroke engines of off-road motorcycles), because the engine works for a long time under full-load high-speed working conditions, the mixed gas is extremely rich, the ignition energy needs to be enhanced, and the combustion process is ensured; and the two-stroke engine ignites every circle, and the ignition frequency is extremely high at high rotating speed.

For the above technical problems, there are two solutions:

one is to adopt high-voltage DC-CDI ignition, namely capacitor ignition, the vehicle-mounted 12V power supply is used for inverting to the voltage above 200V, and the ignition energy and the ignition times are increased in a high-voltage multiple fast-charging and fast-discharging mode; the method has high requirements on the withstand voltage value, capacity and cycle life of the capacitor, and the voltage difference of the inversion system is extremely large, and the requirements on the circuit are extremely high, so that the capacitor is gradually replaced by an inductive ignition coil with larger ignition energy and longer discharge time.

The other is to use a two-way inductive ignition coil, i.e. two ignition coils are alternately charged and discharged to the same spark plug. The ignition coil with good design can easily increase the ignition energy by increasing the magnetizing pulse width, and the alternative ignition of the double ignition coils can increase the working frequency.

Disclosure of Invention

The invention aims to: the invention aims to solve the defects in the prior art and provides an inductive double-ignition system driving circuit of an unmanned aerial vehicle engine, which aims at realizing ignition energy adjustment control and multiple ignition of the double-ignition system.

The technical scheme is as follows: the invention relates to an inductance type double ignition system driving circuit of an unmanned aerial vehicle engine, which comprises two ignition coils and two air cylinders, wherein each air cylinder is provided with two ignition plugs, the ignition coils are in cross connection with the ignition plugs, and the inductance type double ignition system driving circuit also comprises a microcontroller, a DC/DC boosting module, a power driving unit, a current detection unit and a logic control unit; the power driving unit drives the corresponding ignition coil to complete ignition according to a driving signal logic Drive output by the logic control unit after the double ignition system is started, and feeds back a detected primary ignition coil current signal to the current detection unit, wherein the current signal is respectively derived from an Rs+ end and an Rs-end of a precision sampling resistor Rs in a primary ignition coil loop; wherein, two spark plugs of the same cylinder are driven by different ignition coils, and the power driving unit is connected with the ignition primary coil; the current detection amplifier in the current detection unit amplifies the received voltage difference between the Rs+ end and the Rs-end, inputs the amplified voltage difference into two comparators, and controls the output states of the first comparator signal CMP1 and the second comparator signal CMP2 according to the ignition signal Drive and the Mode selection Mode of the microcontroller, and then feeds back the output states to the logic control unit and the microcontroller respectively; after the ignition signal Drive and the mode selection ModeSelect pass through a logic AND gate, when signals on a 7 th pin LATCH2 and a LATCH2 pin of the current sense amplifier are in a high level, the low level state of an output signal ALERT2 of a second comparator of the current sense amplifier is latched, and the ALERT2 signal is a second comparator signal CMP2 after passing through a logic NOT gate; the second comparator signal CMP2 is connected with a 6 th pin LATCH1 of the current sense amplifier, when the signal on the pin LATCH1 is high level, the low level state of the output signal ALERT1 of the first comparator of the current sense amplifier is latched, and the ALERT1 signal is the first comparator signal CMP1 after the logic NOT gate; the microcontroller acquires the time interval of the rising edge of the comparator signal corresponding to the ignition signal Drive so as to judge the working state of the ignition coil, acquires and records the primary current value of the ignition coil in real time, and outputs a high-low level signal according to mode selection ModeSelect to control the latching state of a second comparator signal in the current sense amplifier, namely the microcontroller realizes self-detection and fault diagnosis of the ignition system according to two paths of comparator signals CMP1 and CMP2; the logic control unit determines a driving signal logic Drive finally output to the power driving unit according to an ignition signal Drive of the microcontroller and comparator signals CMP1 and CMP2 of current detection, and respectively realizes an overcurrent turn-off protection function and a multiple ignition function under different Mode selection Mode Select levels (the overcurrent turn-off function is executed when the Mode selection Mode Select is high level, and the multiple ignition function is executed when the Mode selection Mode Select is low level); the DC/DC boosting module boosts the charging voltage VS of the corresponding ignition coil, improves the current rising rate, shortens the time for reaching the required ignition energy (namely the primary current of the ignition coil), thereby reducing the energy loss and the temperature of the ignition coil.

Further, the horizontally opposed double-cylinder engine is provided with two ignition coils and two cylinders, when a double ignition system is adopted, two ignition plugs are arranged on each cylinder, and the ignition coils are in cross connection with the ignition plugs, namely the ignition coil I drives the ignition plug I on the cylinder I and the ignition plug III on the cylinder II, and the ignition coil II drives the ignition plug II on the cylinder I and the ignition plug IV on the cylinder II; the first ignition coil is driven by the first power driving unit to realize ignition, a current signal of the first ignition coil is fed back to the first current detecting unit, the current detecting unit inputs corresponding comparator signals to the microcontroller, the output states of the corresponding comparator signals are controlled according to ignition signals and mode selection of the microcontroller, and finally the corresponding comparator signals are fed back to the logic control unit I and the microcontroller respectively; the second ignition coil is driven by the second power driving unit to realize ignition, a current signal of the second ignition coil is fed back to the second current detecting unit, the second current detecting unit inputs corresponding comparator signals to the microcontroller, the output states of the corresponding comparator signals are controlled according to ignition signals and mode selection of the microcontroller, and finally the second current signals are fed back to the logic control unit and the microcontroller respectively; the two paths of current sense amplifiers share a Mode selection Mode signal output by a data input/output module IO, and current setting Limit1 and Limit2 signals output by two paths of digital-analog conversion modules DAC; for each path of current sensing amplifier, the microcontroller respectively provides two paths of input capturing module IOC capturing comparator signals and one path of analog-digital conversion module ADC measuring current signals.

The structural design of the invention can reduce the number of ignition coils and power driving units, reduce the preparation quality of the unmanned aerial vehicle engine and improve the power-weight ratio; when a single ignition coil fails, the engine can still work normally, and the reliability of the unmanned aerial vehicle is guaranteed.

Further, the power driving unit adopts isolated low-side driving, and comprises a photoelectric isolation chip TLP152, an ignition IGBT chip Q and a precision current sampling resistor Rs; the TLP152 isolates and enhances the driving signal logic driving output by the logic control unit and outputs the driving signal logic driving, when the driving signal logic driving is at a high level, the driving signal logic driving is input by pin a and pin K of the photoelectric isolation driving chip after passing through the current limiting resistor and drives the internal photodiode to emit light, and the secondary photodiode receives the optical signal of the photodiode and then outputs the high level driving signal from pin Vo by the internal push-pull circuit;

the ignition IGBT chip Q (for example, model FGD3440G 2-F085) is internally integrated with the grid driving resistor Rg, the grid discharging resistor Rgs and the clamping diode D, and compared with a common IGBT, the ignition IGBT chip Q can save external components and the area of a cloth plate; the grid electrode of the Ignition IGBT chip Q is connected with the output pin Vo of the photoelectric isolation chip TLP152, the collector electrode is connected with the output voltage VS of the DC/DC boosting module through an Ignition Coil, the emitter electrode is connected to power ground through a precision current sampling resistor Rs, and the Ignition IGBT chip Q controls the on-off of current on the Ignition Coil according to the voltage signal of the output pin Vo of the photoelectric isolation chip TLP 152; the primary current of the ignition coil flowing through a precision electric When the resistor Rs is sampled, the voltage across it

And

is positively correlated with the current, the relationship between the voltage difference and the current is as follows:

。

further, the current detection unit comprises a current signal RC filter circuit, a current sense amplifier (such as INA302A 1) with a two-way comparator and a current sense amplifier peripheral device; the current signal RC filter circuit comprises a filter resistor Rf+, a filter resistor Rf-and a filter capacitor Cf, and voltage values of Rs+ end and Rs-end received from the power driving unit are input to the amplification factor after passing through the RC filter circuitGThe output voltage of the current sense amplifier

And power driving current->

Precision current sampling resistor->

The relation of (2) is as follows:

for example, when the current sense amplifier employs INA302A1, its amplification factor is 20V/V, then

；

The amplified signal is output through the 2 nd pin OUT of the Current sense amplifier to be a Current signal, and then the Current signal is output to the microcontroller; after the analog-digital conversion module ADC of the microcontroller collects the signal, the resistor can be sampled according to the precise current

And current sense amplifier magnificationGCalculating and storing primary current values of the ignition coil in real time, so as to obtain a complete current curve of a single ignition period;

The Current sensing amplifier comprises two paths of comparators, wherein the input positive poles of the two paths of comparators share a Current signal, the input negative pole of a first comparator is corresponding to a Limit1 signal of a 3 rd pin, an ALERT1 signal corresponding to a 12 th pin is output, and a first comparator signal CMP1 is output through an inverting buffer; the second comparator inputs a Limit2 signal of which the negative electrode corresponds to the 9 th pin, outputs an ALERT2 signal of which the negative electrode corresponds to the 11 th pin, and outputs a second comparator signal CMP2 through an inverting buffer; when the Current signal voltage value is greater than the Limit1 signal voltage value, the first comparator signal CMP1 is at a high level, otherwise at a low level, and when the Current signal voltage value is greater than the Limit2 signal voltage value, the second comparator signal CMP2 is at a high level, otherwise at a low level;

the voltage value of the Limit signal is generated and controlled by a digital-to-analog conversion module DAC of the microcontroller, and the current value is set as

The precision current sampling resistor is->

The current sense amplifier has a magnification ofGThe voltage value of Limit signal +.>

The method meets the following conditions:

the Limit1 signal controls the maximum current of the primary of the ignition coil, and the Limit2 signal controls the minimum current of the primary of the ignition coil; the microcontroller is adopted to digitally and analog convert the DAC control current limit value, and different ignition coils can be adjusted and adapted on line without modifying hardware, so that the universality of an electronic control unit is facilitated; for the convenience of operation, a current setting window is reserved in the upper computer, and a plurality of groups of preset currents are provided for quick selection.

Further, the logic control unit is configured with a multifunctional gate chip (for example, SN74LVC1G58 chip), inputs the ignition signal Drive to the 3 rd pin In0, inputs the first comparator signal CMP1 to the 1 st pin In1, inputs the second comparator signal CMP2 to the 6 th pin In2, and has a compact size, simple logic, and a schmitt trigger at the input end, which can effectively resist interference.

Further, an input capturing module IOC, a high-speed analog-to-digital conversion module ADC and a digital-to-analog conversion module DAC are arranged in the microcontroller, and the input capturing module IOC obtains the time interval between the rising edges of the comparator signals CMP11, CMP12, CMP21 and CMP22 and the ignition signal Drive, so as to judge the working state of the ignition coil, and realize the start-up self-inspection and fault diagnosis; under the condition of sufficient system resources, the high-speed analog-digital conversion module ADC can acquire and record the primary current value of the ignition coil in real time, transmit the primary current value to an upper computer operation interface through a communication protocol of the electronic control unit, draw a current curve and provide a visual ignition coil driving current image for a user; and the DAC outputs Limit1 and Limit2 signals to control the maximum current and the minimum current of the primary of the ignition coil.

The microcontroller is a main microcontroller of the electronic control unit, and the electronic control unit calculates the ignition advance angle and the magnetizing time required by the engine work, namely the ending time and the magnetizing pulse width of the output ignition signal Drive according to a series of engine states and environment state parameters such as the current engine throttle opening, the engine rotating speed, the engine working condition, the environment temperature, the cylinder head temperature, the exhaust temperature, the fuel temperature and the like.

Further, the microcontroller outputs a Mode Select signal level to the current detection unit, and when the Mode Select signal level is high, the overcurrent turn-off protection is realized, and the specific method is as follows:

when the Mode selection is high, the ignition signal Drive is high, and the high level is input to the LATCH2 pin after the logic AND gate; when the primary current of the ignition coil reaches the minimum current, the output signal ALERT2 of the second comparator is low level and is latched, namely the second comparator signal CMP2 outputs high level and is latched, and at the moment, the LATCH1 pin inputs high level; when the primary current of the ignition coil reaches the maximum current, the output signal ALERT1 of the first comparator is low level and is latched, i.e. the first comparator signal CMP1 outputs high level and is latched;

The logic control unit controls the output signal logic Drive to be low level according to the detected high level of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2, so that the output protection ignition coil is turned off in time in an overcurrent state. Since the two comparator signals CMP1, CMP2 have been latched high, the latched state can be ended until the ignition signal Drive becomes low, and thus the off output state after overcurrent is maintained until the next ignition Drive.

Further, the microcontroller outputs a Mode Select signal level to the current detection unit, and when the Mode Select signal level is low, the Mode Select signal level realizes multiple ignition, and the specific method is as follows:

when the Mode selection is low, the ignition signal Drive is high, and the low level is input to the LATCH2 pin after the logic AND gate; when the primary current of the ignition coil reaches the minimum current, the output signal ALERT2 of the second comparator is low level and is not latched, namely the second comparator signal CMP2 outputs high level and is not latched, and the LATCH1 pin inputs high level at this time; when the primary current of the ignition coil reaches the maximum current, the output signal ALERT1 of the first comparator is low level and is latched, namely CMP1 outputs high level and is latched;

The logic control unit controls the output signal logic Drive to be low level according to the high level of the detected ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP 2; when the ignition coil primary current decreases between the maximum value and the minimum value, the output signal logic Drive is still low because the comparator signal ALERT1 is latched low, i.e., the first comparator signal CMP1 is latched high; when the primary current of the ignition coil is lower than the minimum value, the comparator signal ALERT2 outputs a high level, namely the second comparator signal CMP2 outputs a low level, at the moment, the LATCH1 pin inputs a low level, and the output signal ALERT1 of the first comparator is unlocked and restored to be a high level, namely the first comparator signal CMP1 outputs a low level; the logic control unit controls the output signal logic Drive to be high level according to the detected high level of the ignition signal Drive and the low level of the first comparator signal CMP1 and the second comparator signal CMP 2;

the ignition system performs the second ignition and repeats until the ignition signal Drive becomes low level;

in summary, when the Mode Select is low, the multiple ignition function can be realized.

When the primary of the ignition coil is turned off, the current drops rapidly (only 1us is needed), but because the secondary coil discharges and induces a higher voltage on the collector electrode of the ignition IGBT, the ignition coil needs to wait for the secondary discharging current to drop and then ignite again, so that a capacitor is connected to the 10 th pin Delay of the current sensing amplifier, and the relation between the capacitance and the signal Delay time of the comparator is as follows:

；

wherein ,

refers to comparator signal delay time, +.>

Refers to the Delay capacitance value accessed by the Delay pin.

Further, the microcontroller performs fault diagnosis protection according to the comparator signal of the current detection unit, and includes the following steps:

after the electronic control unit of the engine is started, each starting self-checking program is carried out, wherein the self-checking program of the ignition system is as follows: the microcontroller outputs an ignition signal Drive for a long time to ensure that the primary current of the ignition coil reaches the saturation current, and outputs a logic Drive high-level signal after passing through the logic control unit, and the power driving unit outputs a driving current; if the state of the ignition coil is normal, the microcontroller sequentially detects a CMP2 high level and a first comparator signal CMP1 high level corresponding to the second comparator within a fixed time after the ignition signal Drive is output, at the moment, the logic control unit output signal logic Drive is changed into a low level to realize overcurrent shutoff, and the first comparator signal CMP1 and the second comparator signal CMP2 output signals are latched into high levels after the primary current of the ignition coil is reduced until the ignition signal Drive is closed;

the self-checking program outputs the high level signal, namely the minimum magnetizing pulse width, according to the detected high level signal of the second comparator signal CMP2 and the time interval from the ignition driving time to the time when the second comparator signal CMP2 outputs the high level signal

Jointly judging that the power driving unit works normally;

based on the detected high signal of the first comparator signal CMP1 and the time interval from the ignition driving time to the time when the first comparator signal CMP1 outputs the high signal, i.e. the maximum magnetizing pulse width

Judging that the fault diagnosis function of the microcontroller is normal together;

then, judging that the fault protection function of the microcontroller works normally according to the detection of the low-level signals of the CMP1 and the CMP2 after the ignition signal Drive is turned off later;

in the step (2), under the fixed driving voltage, the internal resistance and inductance characteristics of the ignition coil are stable,

and />

Are fixed values, and are pre-calibrated>

and />

Recorded in the microcontroller;

the microcontroller then detects CMP1 and CMP2 signals according to each ignition process

and />

Compared with a calibration value, the state of the current power driving circuit and the state of the ignition coil are judged, and specific judgment logic is as follows:

in the driving process of step (2-1), if the high level of the second comparator signal CMP2 is detected, and the acquired time parameter

If the difference from the calibration value is within 10%, judging that the power driving circuit and the ignition coil are normal;

in the driving process of the step (2-2), if the high level of the CMP2 and the high level of the CMP1 are detected successively, and the acquired time parameters are obtained

and />

If the difference from the calibration value is within 10%, judging that the power driving circuit and the ignition coil are normal, but the magnetizing pulse width of the ignition signal Drive is too long, and reminding a user to adjust the magnetizing pulse width;

in the driving process of step (2-3), if the high level of CMP1 and CMP2 cannot be detected and the pulse width of the ignition signal Drive is greater than

When the calibration value is more than twice, judging that one of the ignition coil or the IGBT chip Q is broken;

in the driving process of the step (2-4), if the high level of the CMP2 and the CMP1 is detected, but the time parameter is

And

the ignition signal Drive is rapidly turned off by the microcontroller when the ignition signal Drive is far smaller than the calibration value, and if the low level of the CMP1 and the CMP2 is detected later, the ignition coil is judged to be short-circuited, and the power driving circuit is normal; if the low level of the first comparator signal CMP1 and the second comparator signal CMP2 is not detected for a long time (such as within 10 ms), judging that the ignition coil and the IGBT chip are short-circuited, at the moment, actively cutting off the power supply of the DC/DC boosting module, reminding a user to check the ignition coil and maintaining the power driving unit;

when the ignition coil is short-circuited, the current can rise rapidly, and after the maximum driving current is reached, the logic control unit realizes overcurrent turn-off protection, so that the power driving circuit is better protected.

Further, when the microcontroller is provided with the high-speed analog-to-digital conversion module ADC and the system resources are sufficient, fault diagnosis is performed through the Current signal Current, and at the moment, the fault diagnosis process of the microcontroller is as follows:

after the electronic control unit of the engine is started, each starting self-checking program is carried out, wherein the self-checking program of the ignition system is as follows: the microcontroller outputs an ignition signal Drive for a long time, starts to record a driving current value in real time when the microcontroller outputs the ignition signal Drive, records a waveform of the rising driving current I, and is turned off by hardware after the driving current I reaches the maximum current; the recorded waveform is a standard current waveform;

and (B) comparing the current waveform detected by the microcontroller according to each ignition process with a standard waveform, wherein specific judgment logic is as follows:

in the driving process, if the current waveform of the driving current I detected in the magnetizing pulse width is consistent with the standard current waveform, judging that the power driving circuit and the ignition coil are normal;

in the driving process (B2), if the driving current I is not detected and the pulse width of the ignition signal Drive is greater than

When at least one ignition coil or IGBT chip Q is judged to be open circuit;

In the step (B3) and the driving process, if the rising rate of the driving current I is detected to be far greater than the standard current waveform, the microcontroller rapidly turns off the ignition signal Drive, if the driving current I is detected to be reduced later, the ignition coil is judged to be short-circuited, the power driving circuit is normal, and if the driving current I is detected to be continuously increased later, the ignition coil and the IGBT chip Q are both short-circuited. At this time, the power supply of the DC/DC boosting module is actively cut off, and a user is reminded to check the ignition coil and repair the power driving unit.

The beneficial effects are that: the invention uses the double ignition system to ensure the reliable combustion of the mixed gas in the cylinder; the ignition energy is adaptively adjusted, so that the electric energy consumption is reduced; the multi-ignition ensures cold start in a low-temperature environment, accelerates warm-up, ignites thinner mixed gas, and reduces fuel consumption and emission.

Compared with the prior art, the invention has the following advantages:

(1) The driving circuit has the functions of fault diagnosis and protection and multiple ignition, and is various in functions and wide in use; the driving circuit can be integrated in the ECU, and the volume is small and does not occupy space;

(2) According to the invention, according to the comparator signal and the current signal fed back by the driving circuit, the ignition energy self-adaptive control program of the electronic control unit is combined, so that the magnetizing pulse width can be adjusted in real time according to the working condition requirement of the engine, the working limit and the output power of the engine are improved, and the energy consumption and the heating of the ignition coil are reduced;

(3) The minimum value of the primary current of the ignition coil can be controlled by the microcontroller, so that the universal adaptability of the electronic control unit to ignition coils of different types can be enhanced through the control of the upper computer;

the invention provides a DC/DC booster circuit for the ignition system, shortens the magnetizing pulse width by increasing the driving voltage, reduces the heating of the ignition coil, can provide higher ignition energy, and can realize shorter time and more ignition times.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the present invention;

FIG. 2 is a schematic diagram of a power driving unit according to a first embodiment;

FIG. 3 is a schematic diagram of a current detecting unit according to the first embodiment;

FIG. 4 is a schematic diagram of a logic control unit according to the first embodiment;

FIG. 5 is a schematic diagram of a microcontroller according to a first embodiment;

FIG. 6 is a schematic diagram of a driving current according to the first embodiment;

FIG. 7 is a schematic diagram of a driving current according to the first embodiment;

FIG. 8 is a schematic diagram of a current detecting unit in a second embodiment;

FIG. 9 is a schematic diagram of a logic control unit in a second embodiment;

fig. 10 is a schematic diagram of a microcontroller in a second embodiment.

Detailed Description

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

Example 1

As shown in fig. 1, the driving circuit of the inductive double ignition system of the unmanned aerial vehicle engine of the embodiment comprises two ignition coils and two cylinders, wherein each cylinder is provided with two ignition plugs, the ignition coils are in cross connection with the ignition plugs, and the driving circuit further comprises a microcontroller, a DC/DC boosting module, a power driving unit, a current detection unit and a logic control unit; the power driving unit drives the corresponding ignition coil to complete ignition according to a driving signal logic Drive output by the logic control unit after the double ignition system is started, and feeds back a detected primary ignition coil current signal to the current detection unit, wherein the current signal is respectively derived from an Rs+ end and an Rs-end of a precision sampling resistor Rs in a primary ignition coil loop; wherein, two spark plugs of the same cylinder are driven by different ignition coils, and the power driving unit is connected with the ignition primary coil; the current detection amplifier in the current detection unit amplifies the received voltage difference between the Rs+ end and the Rs-end, inputs the amplified voltage difference into two comparators, and controls the output states of the first comparator signal CMP1 and the second comparator signal CMP2 according to the ignition signal Drive and the Mode selection Mode of the microcontroller, and then feeds back the output states to the logic control unit and the microcontroller respectively; after the ignition signal Drive and the mode selection ModeSelect pass through a logic AND gate, when signals on a 7 th pin LATCH2 and a LATCH2 pin of the current sense amplifier are in a high level, the low level state of an output signal ALERT2 of a second comparator of the current sense amplifier is latched, and the ALERT2 signal is a second comparator signal CMP2 after passing through a logic NOT gate; the second comparator signal CMP2 is connected with a 6 th pin LATCH1 of the current sense amplifier, when the signal on the pin LATCH1 is high level, the low level state of the output signal ALERT1 of the first comparator of the current sense amplifier is latched, and the ALERT1 signal is the first comparator signal CMP1 after the logic NOT gate; the microcontroller acquires the time interval of the rising edge of the comparator signal corresponding to the ignition signal Drive, so that the working state of the ignition coil is judged, the primary current value of the ignition coil is acquired and recorded in real time, and the mode selection ModeSelect outputs a high-low level signal to control the latch state of a second comparator signal in the current sense amplifier; the logic control unit determines a driving signal logic Drive finally output to the power driving unit according to an ignition signal Drive of the microcontroller, a first comparator signal CMP1 and a second comparator signal CMP2, executes an overcurrent shutdown function when a Mode selection is high level, and executes a multiple ignition function when the Mode selection is low level; the DC/DC boost module boosts the charging voltage VS of the corresponding ignition coil.

The engine of the embodiment is provided with two ignition coils and two cylinders, wherein two ignition plugs are arranged on each cylinder, and the ignition coils are connected with the ignition plugs in a cross mode, namely the ignition coil I drives the ignition plug I on the cylinder I and the ignition plug III on the cylinder II, and the ignition coil II drives the ignition plug II on the cylinder I and the ignition plug IV on the cylinder II; the first ignition coil is driven by the first power driving unit to realize ignition, a current signal of the first ignition coil is fed back to the first current detecting unit, the current detecting unit inputs a corresponding comparator signal to the microcontroller, the output state of the corresponding comparator signal is controlled according to an ignition signal and a mode selection signal of the microcontroller, and finally the current signal is fed back to the first logic control unit and the microcontroller respectively; the second ignition coil is driven by the second power driving unit to realize ignition, a current signal of the second ignition coil is fed back to the second current detecting unit, the second current detecting unit inputs corresponding comparator signals to the microcontroller, the output states of the corresponding comparator signals are controlled according to ignition signals and mode selection signals of the microcontroller, and finally the second current signals are fed back to the logic control unit and the microcontroller respectively; the two paths of current sense amplifiers share a mode selection ModeSelect signal output by a data input/output module IO, and current setting Limit1 and Limit2 signals output by two paths of digital-to-analog conversion modules DAC; for each path of current sensing amplifier, the microcontroller respectively provides two paths of input capturing module IOC capturing comparator signals and one path of analog-digital conversion module ADC measuring current signals.

As shown in fig. 2, the power driving unit of the embodiment adopts isolated low-side driving, and comprises a photoelectric isolation chip, an ignition IGBT chip Q and a precision current sampling resistor Rs; the photoelectric isolation chip isolates and enhances the driving signal logic driving output by the logic control unit and outputs the driving signal logic driving, when the driving signal logic driving is at a high level, the driving signal logic driving is input by the pin A and output by the pin K of the photoelectric isolation driving chip after passing through the current limiting resistor and drives the internal photodiode to emit light, and the secondary photodiode receives the optical signal of the photodiode and then outputs the high level driving from the pin Vo by the internal push-pull circuit; the grid driving resistor Rg, the grid discharging resistor Rgs and the clamping diode D are integrated in the Ignition IGBT chip Q, the grid of the Ignition IGBT chip Q is connected with the output pin Vo of the photoelectric isolation chip, the collector is connected with the output voltage VS of the DC/DC boosting module through the Ignition Coil, the emitter is connected to the power ground through the current sampling resistor Rs, and the Ignition IGBT chip Q controls the on-off of current on the Ignition Coil according to the voltage signal of the output pin Vo of the photoelectric isolation chip;

when the primary current of ignition coil flows through the precision current sampling resistor Rs, the voltage between two ends of the resistor

and />

。

as shown in fig. 3, the voltage values of the rs+ end and the Rs-end received by the current detection unit from the power driving unit in this embodiment are input to the amplifying power after passing through the RC filter circuitGThe output voltage of the current sense amplifier

And power driving current->

Precision current sampling resistor->

The relation of (2) is as follows:

the amplified signal is output through the 2 nd pin OUT of the Current sense amplifier to be a Current signal, and then the Current signal is output to the microcontroller; after receiving the Current signal, the microcontroller samples the resistor according to the precise Current

the input anodes of two comparators in the Current sense amplifier share a Current signal, a first comparator signal CMP1 is input with a Limit1 signal of which the negative electrode corresponds to a 3 rd pin, an ALERT1 signal corresponding to a 12 th pin is output, and the first comparator signal CMP1 is output through an inverting buffer; the second comparator inputs Limit2 signal with negative electrode corresponding to 9 th pinOutputting an ALERT2 signal corresponding to the 11 th pin, and outputting a second comparator signal CMP2 through an inverting buffer; when the Current signal voltage value is greater than the Limit1 signal voltage value, the first comparator signal CMP1 is at a high level, and vice versa; when the Current signal voltage value is greater than the Limit2 signal voltage value, the second comparator signal CMP2 is at a high level, and vice versa. The voltage values of the Limit1 signal and the Limit2 signal are generated and controlled by a microcontroller, and the current value is set as

The precision current sampling resistor is->

The method meets the following conditions:

；

the Limit1 signal controls the maximum current of the primary of the ignition coil and the Limit2 signal controls the minimum current of the primary of the ignition coil.

As shown In fig. 4, the logic control unit of the present embodiment is configured with a multi-functional gate chip, inputs the ignition signal Drive to the 3 rd pin In0, inputs the first comparator signal CMP1 to the 1 st pin In1, and inputs the second comparator signal CMP2 to the 6 th pin In2.

As shown in fig. 5, the microcontroller of the present embodiment is provided with an input capturing module IOC, a high-speed analog-to-digital conversion module ADC and a digital-to-analog conversion module DAC, where the input capturing module IOC obtains the time intervals between the rising edges of the four paths CMP11, CMP12, CMP21 and CMP22 of the comparator signals and the ignition signal Drive, so as to determine the working state of the ignition coil, and implement the start-up self-test and fault diagnosis; the high-speed analog-digital conversion module ADC acquires and records the primary current value of the ignition coil in real time, transmits the primary current value to the upper computer operation interface through a communication protocol of the electronic control unit, and draws a current curve; the DAC outputs Limit1 and Limit2 signals to control the maximum current and the minimum current of the primary of the ignition coil.

In the embodiment, the internal resistance of the ignition primary coil is firstly calibrated to be 0.5 omega, the inductance is 2.14mH, and the saturation circuit is 20A; setting the minimum driving current as 6A to ensure the basic ignition energy, and setting the maximum driving current as 15A to avoid invalid heat loss; thus, the current sampling resistor

The microcontroller controls the Limit1 voltage signal to 3V and the Limit2 voltage signal to 1.2V at 10mΩ. The microcontroller outputs a Mode selection Mode Select signal level to the current detection unit according to the working condition of the engine, and when the Mode selection Mode Select is high level, overcurrent turn-off protection is realized, and the specific method is as follows:

The logic control unit controls the output signal logic Drive to be low level according to the detected high level of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2, and finally, the output protection ignition coil is turned off in time in an overcurrent state. The driving current effects are shown in fig. 6 and table 1.

Table 1 drive current variation table

	T0-T1	T1-T2	T2-T3	T3-
					Drive(In0)	L	H	H	H
CMP2 (In 1, latched by Drive signal)	L	L	H	H
					CMP1 (In 2, latched by CMP2 signal)	L	L	L	H
Logical Drive(Y)	L	H	H	L

As can be seen from table 1, at times T0-T1, the ignition signal Drive is low, the first comparator signals CMP1, CMP2 are low, and the logic output signal logic Drive is low; at the time of T1-T2, the ignition signal Drive is high level, the two paths of comparator signals CMP1 and CMP2 are low level, the logic output signal logic Drive is high level, and at the moment, the ignition coil starts to magnetize; if the ignition signal Drive is switched to the low level at this time, the logic output signal logic Drive is also switched to the low level, the ignition coil is magnetized, the ignition plug is ignited, the magnetizing current is shown as a dotted line, and the microcontroller judges that the magnetizing current is insufficient because the rising edge of the second comparator signal CMP2 is not received, and the magnetizing pulse width is increased; at the time of T2-T3, the ignition signal Drive is still at a high level, when the magnetizing current reaches the minimum current 6A at the time of T2, the first comparator signal CMP1 is unchanged, the second comparator signal CMP2 is switched to a high level and is locked to the high level by the ignition signal Drive, and at the moment, the microcontroller judges that the magnetizing current reaches the minimum value according to the rising edge of the second comparator signal CMP 2; if the ignition signal Drive is switched to the low level at this time, the logic output signal LogicalDrive is also switched to the low level, the ignition coil is magnetized, the ignition plug is ignited, and the magnetizing current is shown by a dot-dash line.

If the ignition signal Drive is always kept at a high level, when the magnetizing current reaches the maximum current 15A at time T3, the first comparator signal CMP1 is switched to a high level and is locked to a high level by the second comparator signal CMP2, at this time, the logic output signal logic Drive is switched to a low level, the magnetizing process is forcedly ended and ignited, the magnetizing current is as shown by solid line, and the microcontroller determines that the magnetizing current exceeds the maximum value according to the rising edge of the received first comparator signal CMP1, and the magnetizing pulse width should be reduced. Because of the sequentially latched relationship of the ignition signal Drive, the second comparator signal CMP2 and the first comparator signal CMP1, the logic output signal logic Drive will maintain a low level, avoiding the ignition coil damage caused by the long-term high level of the ignition signal Drive due to the control software error. When the ignition signal Drive is switched to a low level, the second comparator signal CMP2 and the first comparator signal CMP1 are sequentially unlocked, so that it is possible to prepare for the next ignition.

When the Mode Select is at a low level, multiple ignition is realized, and the specific method is as follows:

when the Mode selection is low, the ignition signal Drive is high, and the low level is input to the LATCH2 pin after the logic AND gate; when the primary current of the ignition coil reaches the minimum current, the output signal ALERT2 of the second comparator is low level and is not latched, namely the second comparator signal CMP2 outputs high level and is not latched, and the LATCH1 pin inputs high level at this time; when the primary current of the ignition coil reaches the maximum current, the output signal ALERT1 of the first comparator is low level and is latched, i.e. the first comparator signal CMP1 outputs high level and is locked;

The logic control unit controls the output signal logic Drive to be low level according to the high level of the detected ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP 2; when the ignition coil primary current decreases between the maximum value and the minimum value, the output signal logic Drive is still low because ALERT1 is latched low, i.e., CMP1 is latched high; when the primary current of the ignition coil is lower than the minimum value, the output signal ALERT1 of the first comparator is unlocked and returns to the high level, namely the first comparator signal CMP1 outputs the low level, because the ALERT2 outputs the high level, namely the second comparator signal CMP2 outputs the low level, and the LATCH1 pin inputs the low level at the moment;

the logic control unit controls the output signal logic Drive to be high level according to the detected high level of the ignition signal Drive and the low level of the first comparator signal CMP1 and the second comparator signal CMP 2; the ignition system performs the second ignition and repeats until the ignition signal Drive becomes low level; finally realizing the function of multiple ignition;

the 10 th pin Delay of the current sense amplifier is connected into a capacitor, and the relation between the capacitance value and the signal Delay time of the comparator meets the following conditions:

。

The drive current effect at this time is shown in fig. 7 and table 2.

Table 2 drive current variation table

T0-T1

T1-T2

T2-T3

T3

T4

T5

Drive(In0)

L

H

L

CMP2(In1)

L

H

L

H

CMP1 (In 2, latched by CMP2 signal)

L

H

L

Logical Drive(Y)

L

H

L

H

L

As can be seen from table 2, at time T0-T1, the ignition signal Drive is low, the first comparator signal CMP1 and the second comparator signal CMP2 are low, and the logic output signal logic Drive is low; at the time of T1-T2, the ignition signal Drive is high level, the two paths of comparator signals CMP1 and CMP2 are low level, the logic output signal logic Drive is high level, and at the moment, the ignition coil starts to magnetize; when the magnetizing current reaches the minimum current 6A at time T2, the second comparator signal CMP2 is at T _D After time, switching to a high level and latching the first comparator signal CMP1; when the magnetizing current reaches the maximum current 15A at time T3, the first comparator signal CMP1 switches to a high level and is latched by the second comparator signal CMP 2. At this time, the logic output signal logic Drive is switched to a low level, and the magnetizing process is forcedly ended and ignited; at T when the current decreases to a minimum current of 6A _D After the time, i.e. at time T4, the second comparator signal CMP2 is switched to a low level and the first comparator signal CMP1 is unlocked, so that the first comparator signal CMP1 is also switched to a low level, and at this time, the logic output signal logic Drive is switched to a high level, and the ignition coil starts a new magnetizing process and repeats the ignition process; and after the moment T5 reaches the preset magnetizing pulse width, the ignition signal Drive is switched to a low level, and the last ignition process of multiple ignition is finished.

The microcontroller performs fault diagnosis protection according to the comparator signal of the current detection unit, comprising the steps of:

after the engine electronic control unit is started, the microcontroller outputs an ignition signal Drive for a long time, a logic Drive high-level signal is output after the ignition signal Drive passes through the logic control unit, and the power Drive unit outputs Drive current; if the state of the ignition coil is normal, the microcontroller sequentially detects the high level of the second comparator CMP2 and the high level of the first comparator signal CMP1 in a fixed time after the ignition signal Drive is output, at the moment, the logic control unit output signal logic Drive is changed into a low level to realize overcurrent shutoff, and after the primary current of the ignition coil is reduced, the output signals CMP1 and CMP2 are latched into the high level until the ignition signal Drive is closed;

first, according to the detected high level of the second comparator signal CMP2 and the time interval from the ignition driving time to the time when the second comparator signal CMP2 outputs the high level, namely the minimum magnetizing pulse width

Jointly judging that the power driving unit works normally; then based on the detected high level of the first comparator signal CMP1 and the time interval from the ignition driving time to the time when the first comparator signal CMP1 outputs the high level, that is, the maximum magnetizing pulse width +. >

Judging that the fault diagnosis function of the microcontroller is normal together; then, judging that the fault protection function of the microcontroller works normally according to the detection of the low-level signals of the CMP1 and the CMP2 after the ignition signal Drive is turned off later;

and

are fixed values, and the +.A pre-calibration mode is adopted first>

and />

Recorded in the microcontroller; the microcontroller then detects the CMP1, CMP2 signals from each ignition process and +.>

and />

and />

And

the ignition signal Drive is rapidly turned off by the microcontroller when the ignition signal Drive is far smaller than the calibration value, and if the low level of the CMP1 and the CMP2 is detected later, the ignition coil is judged to be short-circuited, and the power driving circuit is normal; if the low level of the first comparator signal CMP1 and the low level of the second comparator signal CMP2 are not detected for a long time, judging that the ignition coil and the ignition IGBT chip Q are short-circuited, at the moment, actively cutting off the power supply of the DC/DC boosting module, reminding a user to check the ignition coil and maintaining the power driving unit;

When the high-speed analog-to-digital conversion module ADC system resources of the microcontroller are sufficient, fault diagnosis is carried out through the Current signal Current, and the fault diagnosis process of the microcontroller is as follows:

Step (A), the microcontroller outputs an ignition signal Drive for a long time, the driving current value starts to be recorded in real time when the microcontroller outputs the ignition signal Drive, the rising waveform of the driving current I is recorded, and the hardware is turned off after the driving current I reaches the maximum current; the recorded waveform is a standard current waveform;

When the ignition coil or the ignition IGBT chip Q is judged to be open-circuited;

in the step (B3) and the driving process, if the rising rate of the driving current I is detected to be far greater than the standard current waveform, the microcontroller rapidly turns off the ignition signal Drive, if the driving current I is detected to be reduced later, the ignition coil is judged to be short-circuited, the power driving circuit is normal, and if the driving current I is detected to be continuously increased later, the ignition coil and the ignition IGBT chip Q are both short-circuited;

At this time, the DC/DC boost module is actively powered off and the user is alerted to check the ignition coil and repair the power drive unit.

Example two

The technical scheme of the embodiment has comprehensive functions, can realize overcurrent turn-off protection, multiple ignition and the like, but the microcontroller pin occupies more, and can improve the driving circuit as follows if the maximum current/minimum current of the ignition coil does not need to be adjusted on line and the overcurrent turn-off protection is not needed: the current sense amplifier chip and the logic control unit chip are replaced, and the current detection unit and the microcontroller are simplified. As shown in fig. 8 to 10, the specific modifications are as follows:

the current sense amplifier is changed into a window comparator (such as INA303A 1) to output a low-level ALERT signal when the primary current of the ignition coil is lower than the minimum current or higher than the maximum current; the maximum value and the minimum value of the current are respectively set by the resistors RL1 and RL2, so that the following conditions are satisfied:

in addition, in order to reduce the occupation of the IOC pin of the input capturing module of the microcontroller, the first comparator signal CMP1 and the second comparator signal CMP2 are input into the logic AND gate, and then the output comparator signal CMP is transmitted into the microcontroller for fault diagnosis.

According to the changed logic relationship, the configurable multi-functional gate chip SN74LVC1G57 is selected, and the ignition signal Drive is input to the 1 st pin In1, the comparator signal CMP1 is input to the 6 th pin In2, and the comparator signal CMP2 is input to the 3 rd pin In0. The microcontroller of this embodiment cancels the Mode Select signal provided by the input/output module IO in fig. 5, cancels the maximum and minimum Current Limit1 and Limit2 signals provided by the digital-to-analog conversion module DAC, cancels the Current signal Current detection of the analog-to-digital conversion module ADC, and simplifies the two paths of comparator signals captured by the input capturing module IOC into one path of comparator signal CMP, thereby reducing the demands on the pins and resources of the microcontroller to the greatest extent.

Example III

The hardware improvement of the second embodiment can realize multiple ignition, and the implementation method is as follows:

firstly, calibrating the internal resistance of an ignition primary coil to be 0.5 omega, the inductance to be 2.14mH and the saturation circuit to be 20A; setting the minimum driving current as 6A to ensure the basic ignition energy, and setting the maximum driving current as 15A to avoid invalid heat loss; thus, the current sampling resistor

10mΩ, RL1 37.5kΩ, and RL2 15kΩ.

When the ignition signal Drive is at a low level, the first comparator signal CMP1 is at a high level, and the second comparator signal CMP2 is at a low level (the ignition coil primary current is 0, lower than the minimum current); the ignition signal Drive is in a high level, when the primary current of the ignition coil reaches the minimum current, the output of the second comparator signal CMP2 is changed into a high level, and the LATCH1 pin is input in the high level; when the ignition coil primary current reaches a maximum current, the first comparator signal CMP1 output goes low and is locked. The logic control unit controls the output driving signal logic Drive to be a low level according to the detected high level of the ignition signal Drive, the low level of the first comparator signal CMP1 and the high level of the second comparator signal CMP 2; when the ignition coil primary current decreases between the maximum value and the minimum value, the output signal logic Drive is still low because the first comparator signal CMP1 is latched low; when the primary current of the ignition coil is lower than the minimum value, the output of the second comparator signal CMP2 changes to a low level, the low level is input to the LATCH1 pin at the moment, the output of the first comparator signal CMP1 is unlocked and changes to a high level, and the logic control unit controls the output driving signal logic Drive to be a high level according to the fact that the high level of the ignition signal Drive is detected; the ignition system performs the second ignition and repeats until the ignition signal Drive becomes low level.

The drive current effect at this time is shown in fig. 7 and table 3.

Table 3 drive current variation table

T0-T1

T1-T2

T2-T3

T3

T4

T5

Drive(In1)

L

H

L

CMP2(In0)

L

H

L

H

CMP1 (In 2, latched by CMP2 signal)

H

L

H

CMP

L

H

L

H

Logical Drive(Y)

L

H

L

H

L

As can be seen from table 3, at time T0-T1, the ignition signal Drive is low, the first comparator signal CMP1 is high, the second comparator signal CMP2 is low, and the logic output signal logic Drive is low; at the time of T1-T2, the ignition signal Drive is high level, the first comparator signal CMP1 is high level, the second comparator signal CMP2 is low level, the logic output signal logic Drive is high level, and at the moment, the ignition coil starts to magnetize; when the magnetizing current reaches the minimum current 6A at time T2, the second comparator signal CMP2 is at T _D After time, switching to a high level and latching the first comparator signal CMP1; when the magnetizing current reaches the maximum current 15A at time T3, the first comparator signal CMP1 is switched to low level andlatched by the second comparator signal CMP 2. At this time, the logic output signal logic Drive is switched to a low level, and the magnetizing process is forcedly ended and ignited; at T when the current decreases to a minimum current of 6A _D After the time, i.e. at time T4, the second comparator signal CMP2 is switched to a low level and the first comparator signal CMP1 is unlocked, so that the first comparator signal CMP1 is also switched to a high level, and at this time, the logic output signal logic Drive is switched to a high level, and the ignition coil starts a new magnetizing process and repeats the ignition process; and after the moment T5 reaches the preset magnetizing pulse width, the ignition signal Drive is switched to a low level, and the last ignition process of multiple ignition is finished.

Example IV

The embodiment is based on the hardware improvement of the second embodiment, and can realize the initial self-check of the ignition system and the fault diagnosis in the running process of the engine. The fault diagnosis process of the microcontroller comprises the following steps:

after the engine electronic control unit is started, the microcontroller outputs an ignition signal Drive for a long time, a logic Drive high-level signal is output after the ignition signal Drive passes through the logic control unit, and the power Drive unit outputs Drive current; if the state of the ignition coil is normal, the microcontroller sequentially detects the rising edge and the falling edge of the comparator signal CMP within a fixed time after the ignition signal Drive is output; wherein the second comparator signal CMP2 changes from low to high when the primary current of the ignition coil reaches a minimum current, and the first comparator signal CMP1 changes from high to low when the primary current of the ignition coil reaches a maximum current. Thereafter, due to the multiple ignition functions of the driving circuit, the rising edge and the falling edge of the comparator signal CMP are continuously detected until the ignition signal Drive is turned off;

based on the detected rising edge of the comparator signal CMP and the time interval from the ignition driving time to the rising edge time, i.e. the minimum magnetizing pulse width

Jointly judging that the power driving unit works normally; then from the falling edge of the detected comparator signal CMP and the ignition driving time to the lowerThe time interval of the falling edge time, i.e. the maximum magnetizing pulse width

Judging that the fault diagnosis function of the microcontroller is normal together; then according to the rising edge and the falling edge of the comparator signal CMP for a plurality of times and the low level of the comparator signal is detected after the ignition signal Drive is turned off, the normal multi-time ignition function is judged;

and

are fixed values, and are pre-calibrated>

and />

Recorded in the microcontroller; />

The microcontroller then follows the detected comparator signal CMP edge variations for each firing event

And

in the driving process of the step (2-1), if the rising edge of the comparator signal CMP is detected, and the acquired time parameter

in the driving process of the step (2-2), if the rising edge and the falling edge of the comparator signal CMP are detected successively, and the acquired time parameter

and />

in the driving process of step (2-3), if the comparator signal CMP is kept low and the pulse width of the ignition signal Drive is greater than

When the calibration value is more than twice, judging that one of the ignition coil or the ignition IGBT chip Q is open;

in the driving process of the step (2-4), if the rising edge and the falling edge of the comparator signal CMP are detected, but the time parameter is

and />

The microcontroller rapidly turns off the ignition signal Drive when the ignition signal Drive is far smaller than the calibration value, and if the rising edge and the falling edge of the comparator signal CMP are detected later, the ignition coil is judged to be short-circuited, and the power driving circuit is normal; if the change of the comparator signal CMP is not detected for a long time, judging that the ignition coil and the IGBT chip are short-circuited, at the moment, actively cutting off the power supply of the DC/DC boosting module, reminding a user to check the ignition coil and maintaining the power driving unit;

when the ignition coil is short-circuited, the current can rise rapidly, although the overcurrent shutoff function cannot be used, the set delay in the multiple ignition functions can reduce the conduction time of the ignition coil, and the microcontroller is reminded to timely close the ignition signal Drive through continuous comparator signal CMP jump, so that the power driving unit and the ignition coil are protected

The embodiment can continuously realize fault diagnosis and multiple ignition functions, and the required layout space of a circuit board is less, so that the pin and resource occupation of a microcontroller is less.

Claims

1. The utility model provides an inductance type double ignition system drive circuit of unmanned aerial vehicle engine, inductance type double ignition system includes two ignition coil and two cylinders, all installs two spark plugs on every cylinder, cross connection between ignition coil and the spark plug, its characterized in that: the system also comprises a microcontroller, a DC/DC boosting module, a power driving unit, a current detecting unit and a logic control unit;

the power driving unit drives the corresponding ignition coil to complete ignition according to a driving signal logic Drive output by the logic control unit after the double ignition system is started, and feeds back a detected primary ignition coil current signal to the current detection unit, wherein the current signal is respectively derived from an Rs+ end and an Rs-end of a precision sampling resistor Rs in a primary ignition coil loop; wherein, two spark plugs of the same cylinder are driven by different ignition coils, and the power driving unit is connected with the ignition primary coil;

the current detection amplifier in the current detection unit amplifies the received voltage difference between the Rs+ end and the Rs-end, inputs the amplified voltage difference into two comparators, and controls the output states of the first comparator signal CMP1 and the second comparator signal CMP2 according to the ignition signal Drive and the Mode selection Mode of the microcontroller, and then feeds back the output states to the logic control unit and the microcontroller respectively; after the ignition signal Drive and the Mode selection Select pass through the logic AND gate, when the signals on the 7 th pin LATCH2 and the LATCH2 pin of the current sense amplifier are at high level, the low level state of the output signal ALERT2 of the second comparator of the current sense amplifier is latched, and the ALERT2 signal is the second comparator signal CMP2 after passing through the logic NOT gate; the second comparator signal CMP2 is connected with a 6 th pin LATCH1 of the current sense amplifier, when the signal on the pin LATCH1 is high level, the low level state of the output signal ALERT1 of the first comparator of the current sense amplifier is latched, and the ALERT1 signal is the first comparator signal CMP1 after the logic NOT gate;

The microcontroller acquires the time interval of the rising edge of the comparator signal corresponding to the ignition signal Drive so as to judge the working state of the ignition coil, acquires and records the primary current value of the ignition coil in real time, and selects a Mode Select to output a high-low level signal to control the latching state of a second comparator signal in the current sense amplifier according to the Mode;

the logic control unit determines a driving signal logic Drive finally output to the power driving unit according to an ignition signal Drive of the microcontroller, a first comparator signal CMP1 and a second comparator signal CMP2 together, executes an overcurrent shutdown function when a Mode selection Mode is high level, and executes a plurality of ignition functions when the Mode selection Mode is low level;

the DC/DC boost module boosts a charging voltage VS of a corresponding ignition coil.

2. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1, wherein: the specific mode of the cross connection between the ignition coil and the spark plug is that the ignition coil I drives the spark plug I on the first cylinder and the spark plug III on the second cylinder, and the ignition coil II drives the spark plug II on the first cylinder and the spark plug IV on the second cylinder;

The first ignition coil is driven by the first power driving unit to realize ignition, a current signal of the first ignition coil is fed back to the first current detecting unit, the current detecting unit inputs corresponding comparator signals to the microcontroller, the output states of the corresponding comparator signals are controlled according to ignition signals and mode selection of the microcontroller, and finally the corresponding comparator signals are fed back to the logic control unit I and the microcontroller respectively;

the second ignition coil is driven by the second power driving unit to realize ignition, a current signal of the second ignition coil is fed back to the second current detecting unit, the second current detecting unit inputs corresponding comparator signals to the microcontroller, the output states of the corresponding comparator signals are controlled according to ignition signals and mode selection of the microcontroller, and finally the second current signals are fed back to the logic control unit and the microcontroller respectively;

the two paths of current sense amplifiers share a Mode selection Mode signal output by a data input/output module IO, and current setting Limit1 and Limit2 signals output by two paths of digital-analog conversion modules DAC; for each path of current sensing amplifier, the microcontroller respectively provides two paths of input capturing module IOC capturing comparator signals and one path of analog-digital conversion module ADC measuring current signals.

3. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1, wherein: the power driving unit adopts isolated low-side driving and comprises a photoelectric isolation chip, an ignition IGBT chip Q and a precision current sampling resistor Rs; the photoelectric isolation chip isolates and enhances the driving signal logic driving output by the logic control unit and outputs the driving signal logic driving, when the driving signal logic driving is at a high level, the driving signal logic driving is input by the pin A and output by the pin K of the photoelectric isolation driving chip after passing through the current limiting resistor and drives the internal photodiode to emit light, and the secondary photodiode receives the optical signal of the photodiode and then outputs the high level driving signal from the pin Vo by the internal push-pull circuit;

the grid driving resistor Rg, the grid discharging resistor Rgs and the clamping diode D are integrated in the Ignition IGBT chip Q, the grid of the Ignition IGBT chip Q is connected with the output pin Vo of the photoelectric isolation chip, the collector is connected with the output voltage VS of the DC/DC boosting module through the Ignition Coil, the emitter is connected to the power ground through the precision current sampling resistor Rs, and the Ignition IGBT chip Q controls the on-off of current on the Ignition Coil according to the voltage signal of the output pin Vo of the photoelectric isolation chip;

and />

。

4. the unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1, wherein: the voltage values of the Rs+ end and the Rs-end received by the current detection unit from the power driving unit are input to an amplifying rate after being filtered by an RC filter circuitGThe output voltage of the current sense amplifier

And power driving current->

Precision current sampling resistor

The relation of (2) is as follows:

；

the Current signal is shared by the input positive poles of two comparators in the Current sense amplifier, the first comparator signal CMP1 is input with a Limit1 signal of which the negative pole corresponds to the 3 rd pin, an ALERT1 signal corresponding to the 12 th pin is output, and the first comparator signal CMP1 is output through an inverting buffer; the second comparator inputs a Limit2 signal of which the negative electrode corresponds to the 9 th pin, outputs an ALERT2 signal of which the negative electrode corresponds to the 11 th pin, and outputs a second comparator signal CMP2 through an inverting buffer; when the Current signal voltage value is greater than the Limit1 signal voltage value, the first comparator signal CMP1 is at a high level, and vice versa; when the Current signal voltage value is greater than the Limit2 signal voltage value, the second comparator signal CMP2 is at a high level, and vice versa;

The voltage values of the Limit1 signal and the Limit2 signal are generated and controlled by a microcontroller, and the current value is set as

The precision current sampling resistor is->

The method meets the following conditions:

；

5. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1, wherein: the logic control unit is configured with a multifunctional gate chip, inputs an ignition signal Drive to a 3 rd pin In0, inputs a first comparator signal CMP1 to a 1 st pin In1, and inputs a second comparator signal CMP2 to a 6 th pin In2.

6. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1, wherein: the microcontroller is internally provided with an input capturing module IOC, a high-speed analog-digital conversion module ADC and a digital-analog conversion module DAC, wherein the input capturing module IOC acquires the time intervals between the rising edges of four paths of comparator signals CMP11, CMP12, CMP21 and CMP22 and an ignition signal Drive so as to judge the working state of the ignition coil and realize startup self-check and fault diagnosis; the high-speed analog-digital conversion module ADC acquires and records the primary current value of the ignition coil in real time, transmits the primary current value to the upper computer operation interface through a communication protocol of the electronic control unit, and draws a current curve; and the DAC outputs Limit1 and Limit2 signals to control the maximum current and the minimum current of the primary of the ignition coil.

7. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1 or 6, wherein: the microcontroller outputs a Mode selection Mode Select signal level to the current detection unit according to the working condition of the engine, and when the Mode selection Mode Select is high level, overcurrent turn-off protection is realized, and the specific method is as follows:

the logic control unit controls the output signal logic Drive to be low level according to the detected high level of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2, and finally, the output protection ignition coil is turned off in time in an overcurrent state.

8. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1 or 6, wherein: the microcontroller outputs a Mode selection Mode Select signal level to the current detection unit, and when the Mode selection Mode Select is at a low level, the multi-time ignition is realized, and the specific method is as follows:

when the Mode selection is low, the ignition signal Drive is high, and the low level is input to the LATCH2 pin after the logic AND gate; when the primary current of the ignition coil reaches the minimum current, the output signal ALERT2 of the second comparator is low level and is not latched, namely the second comparator signal CMP2 outputs high level and is not latched, and the LATCH1 pin inputs high level at this time; when the primary current of the ignition coil reaches the maximum current, the output signal ALERT1 of the first comparator is low level and is latched, i.e. the first comparator signal CMP1 outputs high level and is latched;

the logic control unit controls the output signal logic Drive to be low level according to the high level of the detected ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP 2; when the ignition coil primary current decreases between the maximum value and the minimum value, the output signal logic Drive is still low since ALERT1 is latched low, i.e., the first comparator signal CMP1 is latched high; when the primary current of the ignition coil is lower than the minimum value, the output signal ALERT1 of the first comparator is unlocked and returns to the high level, namely the first comparator signal CMP1 outputs the low level, because the ALERT2 outputs the high level, namely the second comparator signal CMP2 outputs the low level, and the LATCH1 pin inputs the low level at the moment;

the 10 th pin Delay of the current sense amplifier is connected into a capacitor, and the relation between the capacitance value and the signal Delay time of the comparator is as follows:

；

wherein ,

refers to comparator signal delay time, +.>

Refers to the Delay capacitance value accessed by the Delay pin.

9. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 1 or 6, wherein: the microcontroller performs fault diagnosis protection according to the comparator signal of the current detection unit, and comprises the following steps:

after the engine electronic control unit is started, the microcontroller outputs an ignition signal Drive for a long time, a logic Drive high-level signal is output after the ignition signal Drive passes through the logic control unit, and the power Drive unit outputs Drive current; if the state of the ignition coil is normal, the microcontroller sequentially detects the high level of the second comparator signal CMP2 and the high level of the first comparator signal CMP1 in a fixed time after the ignition signal Drive is output, at the moment, the logic control unit output signal logic Drive is changed into a low level to realize overcurrent shutoff, and the first comparator signal CMP1 and the second comparator signal CMP2 output signals are latched into the high level after the primary current of the ignition coil is reduced until the ignition signal Drive is closed;

First, according to the detected high level signal of the second comparator signal CMP2 and the time interval from the ignition driving time to the time when the second comparator signal CMP2 outputs the high level signal, namely the minimum magnetizing pulse width

Jointly judging that the power driving unit works normally; then, based on the detected high level signal of the first comparator signal CMP1 and the time interval from the ignition driving time to the output high level time of the first comparator signal CMP1, that is, the maximum magnetizing pulse width +.>

Judging that the fault diagnosis function of the microcontroller is normal together; then, according to the low-level signals of the first comparator signal CMP1 and the second comparator signal CMP2 detected after the ignition signal Drive is turned off, the normal work of the fault protection function of the microcontroller is judged;

and />

Are fixed values, and the +.A pre-calibration mode is adopted first>

and />

Recorded in the microcontroller; the microcontroller then generates a first comparator signal CMP1, a second comparator signal CMP2 and +.>

and />

in the driving process of the step (2-2), if the high level of the second comparator signal CMP2 and the high level of the first comparator signal CMP1 are detected in sequence, and the acquired time parameter is obtained

and />

in the driving process of step (2-3), if the high level of the first comparator signal CMP1 and the second comparator signal CMP2 cannot be detected, the pulse width of the ignition signal Drive is larger than

in the driving process of step (2-4), if the high level of the first comparator signal CMP1 and the second comparator signal CMP2 is detected, but the time parameter is

and />

Far less than the calibration value, the microcontroller turns off the ignition signal Drive rapidly at this moment, if the low level of the first comparator signal CMP1 and the second comparator signal CMP2 is detected later, judge the ignition coil is short-circuited, the power Drive circuit is normal; if the low level of the first comparator signal CMP1 and the low level of the second comparator signal CMP2 are not detected for a long time, judging that the ignition coil and the ignition IGBT chip Q are short-circuited, at the moment, actively cutting off the power supply of the DC/DC boosting module, reminding a user to check the ignition coil and maintaining the power driving unit;

10. The unmanned aerial vehicle engine's inductive double ignition system drive circuit of claim 9, wherein: when the microcontroller is provided with a high-speed analog-to-digital conversion module ADC and the system resources are sufficient, fault diagnosis is carried out through a Current signal Current, and the fault diagnosis process of the microcontroller is as follows: