CN115875172A

CN115875172A - Inductance type double-ignition system driving circuit of unmanned aerial vehicle engine

Info

Publication number: CN115875172A
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: 2023-03-31
Anticipated expiration: 2043-03-03
Also published as: CN115875172B

Abstract

The invention discloses an inductive double-ignition system driving circuit of an unmanned aerial vehicle engine.A power driving unit drives a corresponding ignition coil to complete ignition according to a driving signal output by a logic control unit, and feeds back a primary current signal of the ignition coil to a current detection unit; the current detection unit amplifies the difference value of the current signals and inputs the difference value into the two comparators, the signal output state of the comparators is controlled according to the ignition signals and the mode selection signals and is respectively fed back to the logic control unit and the microcontroller, the microcontroller realizes the self-detection and fault diagnosis of the ignition system according to the signals of the two comparators, and the logic control unit determines the final driving signal according to the ignition signals of the microcontroller and the signals of the two comparators. The invention uses the double ignition system to ensure the mixed gas in the cylinder to be reliably combusted; ignition energy is self-adaptively adjusted, and electric energy consumption is reduced; multiple ignition ensures cold start in low-temperature environment, accelerates warming up, can ignite rarer 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 a driving circuit of an ignition system, 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 ignition system ignites gas mixture in a cylinder at a specific moment to expand high-temperature and high-pressure gas and push a piston to do work. Under the emission regulations, the power driving and fault diagnosis module of the vehicle ignition system is mature, and the mainstream scheme is to integrate the module on the top of the ignition coil, and the electronic control unit only outputs a control signal. In order to improve the effective load, the unmanned aerial vehicle pursues lightweight design, 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 realize high reliability of the unmanned aerial vehicle, a double-ignition system with two spark plugs per cylinder is generally adopted, so that ignition system power driving and fault diagnosis modules of an electronic control unit are more complex, and most electronic control units of unmanned aerial vehicle engine manufacturers are only provided with the ignition system power driving modules but not the fault diagnosis modules.

In order to guarantee 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 the 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. High-energy ignition technology and multiple ignition technology can improve the problem, but the high-energy ignition technology puts higher requirements on the reliability of an ignition system and accelerates the ablation of a spark plug, so that self-adaptive ignition energy regulation control is needed to reduce unnecessary power consumption and heating of an ignition coil and prolong the service life of the spark plug and even the whole ignition system; the multiple ignition technology makes a requirement on the rising rate of the driving current of the ignition coil, and a control program with high response rate is required to realize the multiple ignition technology.

The spark ignition system of the existing special unmanned aerial vehicle is usually used for a gasoline engine, and the volatility of gasoline is good, so that the magnetizing pulse width is increased by a small amount and the ignition energy is improved only under special working conditions such as lean combustion, and the like, so that the combustion process is improved and the emission is reduced. For a competition-grade gasoline engine (such as a two-stroke engine of a cross-country motorcycle), because the gasoline engine works under a full-load high-speed working condition for a long time, the mixed gas is extremely rich, ignition energy needs to be enhanced, and the combustion process is ensured; while two-stroke engines ignite every revolution, the frequency of ignition is extremely high at high rotational speeds.

For the above technical problem, there are two solutions:

one is to adopt high voltage DC-CDI ignition, namely capacitor ignition, invert to the voltage above 200V through the on-vehicle 12V power, increase ignition energy and ignition number through the way that high pressure is fast charged many times and is put fast; the method has high requirements on the withstand voltage value, the capacity and the cycle life of the capacitor, the voltage difference of an inverter system is extremely high, the requirement on a circuit is high, and the inverter system is gradually replaced by an inductive ignition coil with larger ignition energy and longer discharge time.

The other method adopts a double-circuit inductance type ignition coil, namely two ignition coils are alternately charged and discharge to the same spark plug. The ignition coil with a good design can easily improve the ignition energy by increasing the magnetizing pulse width, and the alternate ignition of the double ignition coils can improve 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 can realize ignition energy regulation control and multiple ignition aiming at a double-ignition system.

The technical scheme is as follows: the invention discloses an inductive double-ignition system driving circuit of an unmanned aerial vehicle engine, which comprises a microcontroller, a DC/DC boosting module, a power driving unit, a current detection unit and a logic control unit, wherein the microcontroller is used for controlling the DC/DC boosting module to generate a DC/DC voltage; after the double-ignition system is started, the power driving unit drives the corresponding ignition coil to complete ignition according to the driving signal Logical Drive output by the logic control unit, and feeds back the detected primary current signal Rs & lt + & gt and Rs & lt- & gt of the ignition coil to the current detection unit; the current detection unit amplifies the difference value of the received current signals Rs & lt + & gt and Rs & lt- & gt and inputs the amplified current signals into two paths of comparators, and selects a Mode Select according to an ignition signal Drive and a Mode of the microcontroller to control the output states of a first comparator signal CMP1 and a second comparator signal CMP2 so as to feed back the output states to the logic control unit and the microcontroller respectively; after an ignition signal Drive and a Mode selection Mode Select pass through a logic AND gate, the ignition signal Drive and the Mode selection Mode Select are input into a 7 th pin LATCH2 of the current sense amplifier, when a signal on the pin LATCH2 is at a high level, a 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; a second comparator signal CMP2 is connected with a pin 6 LATCH1 of the current sensing amplifier, when a signal on the pin LATCH1 is at a high level, the low level state of an output signal ALERT1 of the first comparator of the current sensing amplifier is latched, and the ALERT1 signal is the first comparator signal CMP1 after passing through a logical 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, collects 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 induction amplifier according to a mode, namely the microcontroller realizes the self-checking and fault diagnosis of the ignition system according to two paths of comparator signals CMP1 and CMP2; the logic control unit jointly 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 multi-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 multi-ignition function is executed when the Mode selection Mode Select is low level); the DC/DC boost module increases the charging voltage VS of the corresponding ignition coil, improves the current rising rate, and shortens the time for reaching the required ignition energy (namely the primary current of the ignition coil), thereby reducing the energy loss and reducing the temperature of the ignition coil.

Furthermore, the horizontally-opposed double-cylinder engine is provided with two ignition coils and two cylinders, when a double-ignition system is adopted, two spark plugs are mounted on each cylinder, the ignition coils and the spark plugs are connected in a cross mode, namely the ignition coil I drives the spark plug I on the cylinder I and the spark plug III on the cylinder II, and the ignition coil II drives the spark plug II on the cylinder I and the spark plug IV on the cylinder II; the ignition coil I is driven by the power driving unit I to realize ignition, and feeds a current signal of the ignition coil I back to the current detection unit I, the current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection of the microcontroller, and finally feeds the output state of the corresponding comparator signal 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, and a current signal of the second ignition coil is fed back to the second current detection unit, the second current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection of the microcontroller, and finally feeds back the output state to the second logic control unit and the microcontroller respectively; the two current sensing amplifiers share a Mode selection Mode Select signal output by the data input/output module IO and current setting Limit1 and Limit2 signals output by the two digital-to-analog conversion modules DAC; aiming at each path of current sensing amplifier, the microcontroller provides two paths of input capture module IOC capture comparator signals and one path of analog-digital conversion module ADC measurement current signals.

The structural design of the invention can reduce the number of ignition coils and power driving units, reduce the engine servicing quality of the unmanned aerial vehicle and improve the power-weight ratio; the engine still can normally work when single ignition coil became invalid, ensures unmanned aerial vehicle's reliability.

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 Logical Drive output by the logic control unit and outputs the signal after driving, when the driving signal Logical Drive is at a high level, the signal is input by the pin a and output by the pin K of the optoelectronic isolation driving chip after passing through the current-limiting resistor and drives the internal photodiode to emit light, and after receiving the optical signal of the photodiode, the secondary photodiode outputs the high-level driving from the pin Vo by the internal push-pull circuit;

the ignition IGBT chip Q (such as model FGD3440G 2-F085) is internally integrated with a gate driving resistor Rg, a gate discharging resistor Rgs and a clamping diode D, and compared with a common IGBT, the ignition IGBT chip Q can save external components and board distribution area; the gate of the Ignition IGBT chip Q is connected to the output pin Vo of the photoelectric isolation chip TLP152, the collector is connected to the output voltage VS of the DC/DC boost 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 the current at the Ignition Coil according to the voltage signal at the output pin Vo of the photoelectric isolation chip TLP 152; when the primary current of the ignition coil flows through the precision current sampling resistor Rs, the voltage difference of voltage signals Rs + and Rs-at two ends of the ignition coil is positively correlated with the current, and the relationship between the voltage difference and the current satisfies the following conditions:

。

further, the current detection unit comprises a current signal RC filter circuit, a current sensing amplifier (such as INA302A 1) with a dual-path comparator and a current sensing amplifier peripheral device; the current signal RC filter circuit comprises a filter resistor Rf +, a filter resistor Rf-and a filter capacitor Cf, and the current signals Rs + and Rs-received from the power driving unit are input to the RC filter circuit with the amplification factor ofGCurrent sense amplifier of

And the power driving current->

And a current sampling resistance->

Satisfies the following relationship:

for example, when the current sense amplifier employs INA302A1The magnification is 20V/V, then

；

The amplified signal is a Current signal which is output by a pin 2 OUT of the Current sensing amplifier, 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 current

And current sense amplifier amplificationGCalculating and storing the primary current value of the ignition coil in real time, thereby obtaining a complete current curve of a single ignition period;

the input anodes of two comparators in the Current sensing amplifier share a Current signal, the input cathode of a first comparator corresponds to a Limit1 signal of a3 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 corresponding to the 11 th pin, and outputs a second comparator signal CMP2 through the inverting buffer; when the voltage value of the Current signal is greater than the voltage value of the Limit1 signal, the first comparator signal CMP1 is at a high level, otherwise, the first comparator signal CMP1 is at a low level, and when the voltage value of the Current signal is greater than the voltage value of the Limit2 signal, the second comparator signal CMP2 is at a high level, otherwise, the second comparator signal CMP2 is 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 to be

The current sampling resistor is->

And a current sense amplifier amplification ofGThe voltage value of the Limit signal

Satisfies the following conditions:

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

Furthermore, the logic control unit is configured with a multifunctional gate chip (for example, an SN74LVC1G58 chip), the ignition signal Drive is input to the pin 3 In0, the first comparator signal CMP1 is input to the pin 1 In1, the second comparator signal CMP2 is input to the pin 6 In2, the multifunctional gate chip is small and exquisite In size and simple In logic, and the input end is provided with a schmitt trigger, so that interference can be effectively resisted.

Furthermore, an input capture module IOC, a high-speed analog-digital conversion module ADC and a digital analog conversion module DAC are arranged in the microcontroller, and the input capture module IOC acquires the time interval of the rising edges of comparator signals CMP11, CMP12, CMP21 and CMP22 relative to an ignition signal Drive, so that the working state of the ignition coil is judged, and power-on self-checking and fault diagnosis are realized; under the condition of sufficient system resources, the high-speed analog-digital conversion module ADC can collect and record the primary current value of the ignition coil in real time, transmit the primary current value to an operation interface of an upper computer through a communication protocol of an electronic control unit, draw a current curve and provide an intuitive 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 side of the ignition coil.

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

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

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

the logic control unit controls the output signal Logical Drive to be low level according to the detected high levels of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2, thereby realizing timely turn-off of the output protection ignition coil in an overcurrent state. Since the two comparator signals CMP1, CMP2 are already latched high, the latching state cannot be ended until the ignition signal Drive changes to low level, and thus the off output state after overcurrent is maintained until the next ignition driving.

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

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

the logic control unit controls the output signal logic Drive to be low level according to the detected high levels of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2; when the primary current of the ignition coil is reduced to be between the maximum value and the minimum value, the output signal Logical Drive is still at a low level because the comparator signal ALERT1 is latched to a low level, namely the first comparator signal CMP1 is latched to a high level; 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 pin LATCH1 inputs a low level, the output signal ALERT1 of the first comparator is unlocked and restored to the 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 high level of the ignition signal Drive, the low level of the first comparator signal CMP1 and the low level of the second comparator signal CMP2;

at the moment, the ignition system carries out second ignition and repeats until the ignition signal Drive becomes low level;

in summary, when the Mode selection Mode Select is low, the multi-ignition function can be realized.

When ignition coil is elementary to turn off, the electric current descends fast (only need 1 us), but because secondary coil discharge induction, ignition coil is elementary to induce higher voltage on the collector electrode of ignition IGBT, need wait for secondary discharge current to descend the back and ignite once more, consequently inserts electric capacity at current sense amplifier's 10 th pin Delay, and the relation of electric capacity value and comparator signal Delay time satisfies:

；

wherein ,

means that the comparator signal is delayed by a time>

The capacitance value of the Delay capacitor connected to the Delay pin is referred to.

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

step (1), after the engine electronic control unit is started, various power-on self-test programs are carried out, wherein the ignition system self-test program 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 a saturation current, a logic Drive high-level signal is output after the ignition coil passes through the logic control unit, and the power driving unit outputs a driving current; if the ignition coil state is normal, the microcontroller sequentially detects a CMP2 high level corresponding to the second comparator and a CMP1 high level of a first comparator signal within a fixed time after the ignition signal Drive is output, at the moment, the logic control unit outputs a signal, namely a logic Drive, to be changed into a low level to realize overcurrent turn-off, and after the primary current of the ignition coil is reduced, the output signals of the first comparator signal CMP1 and the second comparator signal CMP2 are latched into a high level until the ignition signal Drive is turned off;

the self-test program detects the high level signal of the second comparator signal CMP2 and the time interval from the ignition driving moment to the high level output moment of the second comparator signal CMP2, namely the minimum magnetizing pulse width

Jointly judging that the power driving unit works normally;

based on the detected high level signal of the first comparator signal CMP1 and the time interval from the time of the ignition driving to the time of the output high level of the first comparator signal CMP1, 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 low level signals of CMP1 and CMP2 detected after the ignition signal Drive is turned off;

step (2), under the fixed driving voltage, because the resistance inductance characteristic in the ignition coil is stable,

and

are all fixed values and are intended to be pre-calibrated>

and />

Recording in a microcontroller;

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

and />

And comparing the current state of the power driving circuit and the ignition coil with a calibration value, wherein the 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 between the standard value and the standard value is within 10 percent, the power driving circuit and the ignition coil are judged to be normal; />

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

and />

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

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

Calibration valueWhen the current is more than twice, judging that one of the ignition coil or the IGBT chip Q is disconnected;

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

and />

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

when the ignition coil is in short circuit, 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 protected better.

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

after the electronic control unit of the engine is started, various power-on self-test programs are carried out, wherein the self-test program of the ignition system is as follows: the microcontroller outputs an ignition signal Drive for a long time, the driving current value is recorded in real time when the microcontroller outputs the ignition signal Drive, and the rising waveform of the driving current I is recorded until the driving current I reaches the maximum current and then is turned off by hardware; the recorded waveform is a standard current waveform;

step (B), the microcontroller compares the current waveform detected in each ignition process with a standard waveform, and the specific judgment logic is as follows:

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

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

When the ignition coil is in the open state, judging that at least one of the ignition coil and the IGBT chip Q is in the open state;

and (B3) in 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 quickly turns off the ignition signal Drive, if the driving current I is detected to fall later, the ignition coil is judged to be in short circuit, the power driving circuit is normal, and if the driving current I is detected to continuously rise later, the ignition coil and the IGBT chip Q are both in short circuit. At the moment, the power supply of the DC/DC boosting module is actively cut off, and a user is reminded to check the ignition coil and maintain the power driving unit.

Has the advantages that: the invention uses the double ignition system to ensure the mixed gas in the cylinder to be reliably combusted; ignition energy is self-adaptively adjusted, and electric energy consumption is reduced; multiple ignition ensures cold start in low-temperature environment, accelerates warming up, can ignite rarer 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 multifunctional and widely used; the driving circuit can be integrated in an ECU (electronic control unit), and has small volume and no space occupation;

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

(3) The minimum value of the maximum 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 models can be enhanced through the control of an upper computer;

the invention provides the ignition system with the DC/DC booster circuit, 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 more ignition times in a short time.

Drawings

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

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

FIG. 3 is a schematic diagram of a current detection unit according to an embodiment;

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

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

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

FIG. 7 is a schematic diagram of driving currents according to one embodiment;

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

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

FIG. 10 is a diagram of a microcontroller according to a second embodiment.

Detailed Description

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

Example one

As shown in fig. 1, the inductive dual-ignition system driving circuit of the engine of the unmanned aerial vehicle of the present embodiment includes a microcontroller, a DC/DC boost module, a power driving unit, a current detection unit, and a logic control unit; after the double-ignition system is started, the power driving unit drives the corresponding ignition coil to finish ignition according to the driving signal Logical Drive output by the logic control unit, and feeds back the detected primary current signals Rs & lt + & gt and Rs & lt- & gt of the ignition coil to the current detection unit; the current detection unit amplifies the difference value of the received current signal Rs + and Rs-and inputs the amplified difference value into two comparators, and controls the output states of a first comparator signal CMP1 and a second comparator signal CMP2 according to an ignition signal Drive and a Mode selection of the microcontroller, and then feeds the output states back to the logic control unit and the microcontroller respectively; after an ignition signal Drive and a Mode selection Mode Select pass through a logic AND gate, the ignition signal Drive and the Mode selection Mode Select are input into a 7 th pin LATCH2 of the current sense amplifier, when a signal on the pin LATCH2 is at a high level, a 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; a second comparator signal CMP2 is connected with a pin 6 LATCH1 of the current sensing amplifier, when a signal on the pin LATCH1 is at a high level, the low level state of an output signal ALERT1 of the first comparator of the current sensing amplifier is latched, and the ALERT1 signal is the first comparator signal CMP1 after passing through a logical NOT gate; the microcontroller acquires a time interval of a rising edge of a comparator signal corresponding to an ignition signal Drive so as to judge the working state of the ignition coil, collects 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 sensing amplifier according to a 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, and executes an overcurrent turn-off function when the Mode selection Mode is high level and executes a multi-time ignition function when the Mode selection Mode 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 each cylinder is provided with two spark plugs, and the ignition coils and the spark plugs are in cross connection, namely the ignition coil I drives the spark plug I on the cylinder I and the spark plug III on the cylinder II, and the ignition coil II drives the spark plug II on the cylinder I and the spark plug IV on the cylinder II; the ignition coil I is driven by the power driving unit I to realize ignition, and feeds a current signal of the ignition coil I back to the current detection unit I, the current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection signal of the microcontroller, and finally feeds the output state of the corresponding comparator signal 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, and a current signal of the second ignition coil is fed back to the second current detection unit, the second current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection signal of the microcontroller, and finally feeds back the output state to the second logic control unit and the microcontroller respectively; the two current sensing amplifiers share a Mode selection Mode Select signal output by the data input/output module IO and current setting Limit1 and Limit2 signals output by the two digital-to-analog conversion modules DAC; aiming at each path of current sensing amplifier, the microcontroller provides two paths of input capture module IOC capture comparator signals and one path of analog-digital conversion module ADC measurement current signals.

As shown in fig. 2, the power driving unit of the present embodiment adopts an isolated low-side drive, and includes a photoelectric isolation chip, an ignition IGBT chip Q, and a precision current sampling resistor Rs; the photoelectric isolation chip isolates the driving signal Logical Drive output by the logic control unit and enhances the driving for outputting, when the driving signal Logical Drive is at a high level, the driving signal Logical Drive passes through the current-limiting resistor and is input by the pin A and output by the pin K of the photoelectric isolation driving chip and drives the internal photodiode to emit light, and after the secondary photodiode receives the optical signal of the photodiode, the internal push-pull circuit outputs a high level from the pin Vo for driving; a grid driving resistor Rg, a grid discharging resistor Rgs and a clamping diode D are integrated in the Ignition IGBT chip Q, the grid of the Ignition IGBT chip Q is connected with an output pin Vo of the photoelectric isolation chip, a collector is connected with the output voltage VS of the DC/DC boost module through an Ignition Coil, an emitter is connected to the power ground through a current sampling resistor Rs, and the Ignition IGBT chip Q controls the on-off of the 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 the ignition coil flows through the precision current sampling resistor Rs, the voltage difference of voltage signals Rs + and Rs-at two ends of the ignition coil is positively correlated with the current, and the relationship between the voltage difference and the current meets the following requirements:

。

as shown in FIG. 3, the current detection unit of this embodiment receives the current signals Rs + and Rs-from the power driving unit, passes through the RC filter circuit, and then inputs the current signals to the amplification circuit with the amplification factor ofGCurrent sense amplifier of

And the power driving current->

And a current sampling resistance->

Satisfies the following relationship:

the amplified signal is a Current signal which is output by a pin 2 OUT of the Current sensing amplifier, and then the Current signal is output to the microcontroller; the microcontroller samples the resistor according to the Current after receiving the Current signal

the input anodes of two comparators in the Current sensing amplifier share a Current signal, a first comparator signal CMP1 is input into a Limit1 signal of which the cathode corresponds to a3 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 a Limit2 signal of which the negative electrode corresponds to the 9 th pin, outputs an ALERT2 signal corresponding to the 11 th pin, and outputs a second comparator signal CMP2 through the inverting buffer; when the voltage value of the Current signal is greater than the voltage value of the Limit1 signal, the first comparator signal CMP1 is at a high level, otherwise, the first comparator signal CMP1 is at a low level; 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 values of the Limit1 signal and the Limit2 signal are generated and controlled by a microcontroller,set the current value to

The current sampling resistor is->

And a current sense amplifier amplification ofGIf so, the voltage value of the Limit signal is->

Satisfies the following conditions:

；

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

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

As shown in fig. 5, the microcontroller of this embodiment is provided with an input capture module IOC, a high-speed analog-to-digital conversion module ADC, and a digital analog-to-digital conversion module DAC, where the input capture module IOC obtains time intervals between rising edges of four paths of comparator signals CMP11, CMP12, CMP21, and CMP22 and an ignition signal Drive, so as to determine a working state of an ignition coil, and implement power-on self-test and fault diagnosis; the high-speed analog-digital conversion module ADC collects and records the primary current value of the ignition coil in real time, transmits the primary current value to an operation interface of an upper computer 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 ignition coil primary.

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

And the voltage signal is 10m omega, the microcontroller controls the voltage signal of the Limit1 to be 3V, and the voltage signal of the Limit2 to be 1.2V. 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 a high level, overcurrent turn-off protection is realized, and the specific method comprises the following steps:

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 effect of the drive current is shown in fig. 6 and table 1.

TABLE 1 drive Current Change Meter

	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 time T0 to T1, the ignition signal Drive is at a low level, the first comparator signals CMP1 and CMP2 are at a low level, and the logic output signal Logical Drive is at a low level; at the time of T1-T2, an ignition signal Drive is at a high level, two comparator signals CMP1 and CMP2 are at a low level, a logic output signal Logical Drive is at a high level, and at the moment, an ignition coil starts to magnetize; if the ignition signal Drive is switched to a low level, the logic output signal Logical Drive is also switched to the low level, the ignition coil is magnetized, the spark plug is ignited, the magnetizing current is shown by 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 the 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 received second comparator signal CMP2; if the ignition signal Drive is switched to a low level at the moment, the logic output signal logistic Drive is also switched to a low level, the ignition coil is magnetized, the spark plug is ignited, and the magnetizing current is shown as 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 the time T3, the first comparator signal CMP1 is switched to a high level and is locked to the high level by the second comparator signal CMP2, the logic output signal logic Drive is switched to a low level at the moment, the magnetizing process is forcibly ended and ignition is carried out, the magnetizing current is shown as a solid line, the microcontroller judges 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 is reduced. Because the ignition signal Drive, the second comparator signal CMP2 and the first comparator signal CMP1 are sequentially latched, the logic output signal logic Drive maintains a low level, and the damage of the ignition coil caused by the long-term high level of the ignition signal Drive when the control software is wrong is avoided. When the ignition signal Drive is switched to low level, the second comparator signal CMP2 and the first comparator signal CMP1 are sequentially unlocked, so that the next ignition can be ready to be entered.

When the Mode selection Mode is at a low level, multiple ignitions are realized, and the specific method comprises the following steps:

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

the logic control unit controls the output signal logic Drive to be low level according to the detected high levels of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2; when the primary current of the ignition coil is reduced to be between the maximum value and the minimum value, the output signal Logical Drive is still at a low level because the ALERT1 is latched to a low level, namely the CMP1 is latched to a high level; when the primary current of the ignition coil is lower than the minimum value, as the 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, the output signal ALERT1 of the first comparator is unlocked and restored to the high level, namely the first comparator signal CMP1 outputs a low level;

the logic control unit controls the output signal Logical Drive to be high level according to the detected high level of the ignition signal Drive, the low level of the first comparator signal CMP1 and the second comparator signal CMP2; at the moment, the ignition system carries out second ignition and repeats until the ignition signal Drive becomes low level; finally, the function of multiple ignition is realized;

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

。

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

TABLE 2 Driving Current Change 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 to T1, the ignition signal Drive is at a low level, the first comparator signal CMP1 and the second comparator signal CMP2 are at a low level, and the logic output signal Logical Drive is at a low level; at the time of T1-T2, an ignition signal Drive is at a high level, two comparator signals CMP1 and CMP2 are at a low level, a logic output signal Logical Drive is at a high level, and at the moment, an ignition coil starts to magnetize; when the magnetizing current reaches the minimum current of 6A at time T2, the second comparator signal CMP2 is at T _D Switching to a high level after time and latching a first comparator signal CMP1; when the magnetizing current reaches the maximum current 15A at time T3, the first comparator signal CMP1 switches to the high level and is latched by the second comparator signal CMP 2. At the moment, the logic output signal logic Drive is switched to a low level, and the magnetizing process is forcibly ended and ignited; at T when the current is reduced to a minimum current of 6A _D After time, namely at time T4, the second comparator signal CMP2 is switched to the low level and unlocks the first comparator signal CMP1, so that the first comparator signal CMP1 is also switched to the low level, at this time, the logic output signal logic Drive is switched to the high level, the ignition coil starts a new magnetizing process, and the ignition process is repeated; and after the time T5 reaches the preset magnetizing pulse width, the ignition signal Drive is switched to a low level, and the last ignition process of multiple times of ignition is finished.

The microcontroller executes fault diagnosis protection according to a comparator signal of the current detection unit, and comprises the following steps:

after an electronic control unit of an engine is started, a 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 a logic control unit, and a power driving unit outputs driving current; if the ignition coil is in a normal state, the microcontroller sequentially detects the high level of a second comparator CMP2 and the high level of a first comparator signal CMP1 within a fixed time after the ignition signal Drive is output, at the moment, the logic control unit outputs a signal logic Drive which 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 a high level until the ignition signal Drive is closed;

based on the detected high level of the second comparator signal CMP2 and the time interval from the time of the ignition driving to the time of the output high level of the second comparator signal CMP2, i.e. the minimum magnetizing pulse width

Jointly judging that the power driving unit works normally; based on the detected high level of the first comparator signal CMP1 and the time interval from the moment of ignition drive to the moment of output of high level of the first comparator signal CMP1, i.e. the maximum pulse width for magnetization->

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 low level signals of CMP1 and CMP2 detected after the ignition signal Drive is turned off;

and

are all fixed values and are first pre-calibrated>

and />

Recording in a microcontroller; the microcontroller then detects the CMP1, CMP2 signals and->

and />

And comparing the current power driving circuit with a calibration value, and judging the states of the current power driving circuit and the ignition coil, wherein the specific judgment logic is as follows:

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

If the difference between the standard value and the standard value is within 10 percent, the power driving circuit and the ignition coil are judged to be normal;

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

and />

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

When the calibrated value is more than two times, judging that one of an ignition coil or an IGBT chip Q is disconnected;

and />

The ignition signal Drive is quickly turned off by the microcontroller when the ignition signal Drive is far smaller than a calibrated value, and if the low levels of CMP1 and CMP2 are detected later, the ignition coil is judged to be short-circuited, and the power driving circuit is normal; if the low levels of the first comparator signal CMP1 and the second comparator signal CMP2 are not detected for a long time, the ignition coil and the ignition IGBT chip Q are judged to be short-circuited, at the moment, the power supply of the DC/DC boosting module is actively cut off, a user is reminded to check the ignition coil, and the power driving unit is maintained;

When the resources of an ADC (analog-to-digital converter) system of a high-speed ADC (analog-to-digital converter) of the microcontroller are sufficient, fault diagnosis is carried out through a Current signal, 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 is recorded in real time when the microcontroller outputs the ignition signal Drive, and the rising waveform of the driving current I is recorded until the driving current I reaches the maximum current and then is turned off by hardware; the recorded waveform is a standard current waveform;

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

When the ignition is started, judging that at least one of the ignition coil or the ignition IGBT chip Q is in open circuit;

in the step (B3) and the driving process, if the rising rate of the driving current I is detected to be far larger than the standard current waveform, the microcontroller quickly turns off an ignition signal Drive, if the driving current I is detected to fall 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 continuously rise later, the ignition coil and the ignition IGBT chip Q are both short-circuited;

at the moment, the power supply of the DC/DC boosting module is actively cut off, and a user is reminded to check an ignition coil and maintain the power driving unit.

Example two

The technical scheme of the embodiment has comprehensive functions, can realize overcurrent turn-off protection, repeated ignition and the like, but the pin of the microcontroller occupies more, if the maximum current/minimum current of the ignition coil does not need online adjustment and overcurrent turn-off protection is not needed, the following improvement can be made on the drive circuit: the chip of the current sensing amplifier and the chip of the logic control unit are replaced, and the current detection unit and the microcontroller are simplified. As shown in fig. 8 to 10, the specific improvements are as follows:

the current sensing amplifier is changed into a window comparator (such as INA303A 1) and outputs 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, and satisfy the following conditions:

in addition, in order to reduce the occupation of the input capture module IOC pins of the microcontroller, the comparator signals CMP output after the first comparator signals CMP1 and the second comparator signals CMP2 are input into the logic AND gate are transmitted into the microcontroller for fault diagnosis.

According to the changed logic relation, the configurable multi-function 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 selection 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 reduces the two comparator signals captured by the input capture module IOC into one comparator signal CMP, thereby reducing the requirements for the pins and resources of the microcontroller to the maximum extent.

EXAMPLE III

In this embodiment, multiple ignitions can be realized based on the hardware improvement of the second embodiment, 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 a saturation circuit to be 20A; then set the minimum drive current to 6A to ensure the basic ignition energySetting the maximum drive current to 15A avoids ineffective heat loss; thus, the current sampling resistor

10 m.OMEGA., 37.5

k.OMEGA.RL

1 and 15 k.OMEGA.RL 2.

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 high level, when the primary current of the ignition coil reaches the minimum current, the output of a second comparator signal CMP2 is changed into high level, and at the moment, a pin LATCH1 inputs high level; when the ignition coil primary current reaches the maximum current, the first comparator signal CMP1 output goes low and is locked. The logic control unit controls the output driving signal Logical Drive to be at 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 CMP2; when the ignition coil primary current is reduced to be between the maximum value and the minimum value, the output signal Logical Drive is still at a low level because the first comparator signal CMP1 is latched to be at a low level; when the primary current of the ignition coil is lower than the minimum value, the output of a second comparator signal CMP2 is changed into a low level, at the moment, a pin LATCH1 inputs a low level, the output of a first comparator signal CMP1 is unlocked and changed into a high level, and a logic control unit controls the output driving signal logic Drive to be a high level according to the detected high level of an ignition signal Drive, the low level of the first comparator signal CMP1 and the high level of the second comparator signal CMP2; the ignition system performs a second ignition and repeats until the ignition signal Drive goes low.

The effect of the driving current at this time is shown in fig. 7 and table 3.

TABLE 3 drive Current Change 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 to T1, the ignition signal Drive is at a low level, the first comparator signal CMP1 is at a high level, the second comparator signal CMP2 is at a low level, and the logic output signal logic Drive is at a low level; at the time of T1-T2, the ignition signal Drive is at a high level, the first comparator signal CMP1 is at a high level, the second comparator signal CMP2 is at a low level, the logic output signal Logical Drive is at a high level, and the ignition coil starts to be magnetized; when the magnetizing current reaches the minimum current of 6A at time T2, the second comparator signal CMP2 is at T _D Switching to high level after time and latching a first comparator signal CMP1; when the magnetizing current reaches the maximum current 15A at time T3, the first comparator signal CMP1 switches to the low level and is latched by the second comparator signal CMP 2. At the moment, the logic output signal logic Drive is switched to a low level, and the magnetizing process is forcibly ended and ignited; at T when the current is reduced to a minimum current of 6A _D After time, namely at time T4, the second comparator signal CMP2 is switched to a low level and unlocks the first comparator signal CMP1, so that the first comparator signal CMP1 is also switched to a high level, at this time, the logic output signal logic Drive is switched to a high level, the ignition coil starts a new magnetizing process, and the ignition process is repeated; until the time T5 reaches the preset magnetizing pulse width, the ignition signal Drive is switched to low level for multiple timesThe last firing process of the firing is completed.

Example four

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

after an electronic control unit of an engine is started, a 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 a logic control unit, and a power driving unit outputs driving current; if the ignition coil state is normal, the microcontroller sequentially detects the rising edge and the falling edge of a comparator signal CMP within a fixed time after the ignition signal Drive is output; the second comparator signal CMP2 changes from low to high when the rising edge corresponds to the ignition coil primary current reaching the minimum current, and the first comparator signal CMP1 changes from high to low when the falling edge corresponds to the ignition coil primary current reaching the maximum current. Then, 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 based on the detected falling edge of the comparator signal CMP and the time interval from the ignition drive time to the falling edge time, i.e. the maximum magnetizing pulse width

Judging that the fault diagnosis function of the microcontroller is normal together; then judging that the multiple ignition function is normal according to the rising edge and the falling edge of the subsequent multiple comparator signal CMP and the low level of the comparator signal detected after the ignition signal Drive is turned off;

and

are all fixed values and are intended to be pre-calibrated>

and />

Recording in a microcontroller;

the microcontroller then detects, from each ignition event, a change in the comparator signal CMP edge and

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 in sequence, and the acquired time parameter

and />

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

When the calibrated value is more than two times, judging that one of the ignition coil or the ignition IGBT chip Q is open-circuited;

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

and />

When the current value is far smaller than the calibration value, the microcontroller quickly turns off the ignition signal Drive, 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, the ignition coil and the IGBT chip are judged to be short-circuited, the DC/DC boosting module is actively cut off to supply power, and a user is reminded to check the ignition coil and maintain the power driving unit;

when the ignition coil is in short circuit, the current can rise rapidly, although the over-current turn-off function cannot be used, the on-time of the ignition coil can be reduced by setting delay in the ignition function for multiple times, and the microcontroller is reminded to timely turn off the ignition signal Drive through continuous CMP jumping of a comparator signal, so that the power driving unit and the ignition coil are protected

The embodiment can not only continuously realize the functions of fault diagnosis and multiple ignition, but also requires less layout space of the circuit board and occupies less pins and resources of the microcontroller.

Claims

1. The utility model provides an unmanned aerial vehicle engine's inductance type dual ignition system drive circuit which characterized in that: the device comprises a microcontroller, a DC/DC boosting module, a power driving unit, a current detection unit and a logic control unit;

after the double-ignition system is started, the power driving unit drives the corresponding ignition coil to finish ignition according to the driving signal Logical Drive output by the logic control unit, and feeds back the detected primary current signals Rs & lt + & gt and Rs & lt- & gt of the ignition coil to the current detection unit;

the current detection unit amplifies the difference value of the received current signals Rs & lt + & gt and Rs & lt- & gt and inputs the amplified current signals into two paths of comparators, and selects a Mode Select according to an ignition signal Drive and a Mode of the microcontroller to control the output states of a first comparator signal CMP1 and a second comparator signal CMP2 so as to feed back the output states to the logic control unit and the microcontroller respectively; after an ignition signal Drive and a Mode selection Mode Select pass through a logic AND gate, the ignition signal Drive and the Mode selection Mode Select are input into a 7 th pin LATCH2 of the current sense amplifier, when a signal on the pin LATCH2 is at a high level, a 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; a second comparator signal CMP2 is connected with a 6 th pin LATCH1 of the current sensing amplifier, when a signal on the LATCH1 pin is in a high level, a low level state of an output signal ALERT1 of a first comparator of the current sensing amplifier is latched, and the ALERT1 signal is a first comparator signal CMP1 after passing through a logical NOT gate;

the microcontroller acquires a time interval of a rising edge of a comparator signal corresponding to an ignition signal Drive so as to judge the working state of the ignition coil, collects 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 induction amplifier according to a 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, and executes an overcurrent turn-off function when the Mode selection Mode is high level and executes a multi-time ignition function when the Mode selection Mode is low level;

and the DC/DC boosting module is used for boosting the charging voltage VS of the corresponding ignition coil.

2. The inductive dual ignition system drive circuit of unmanned aerial vehicle engine of claim 1, characterized in that: the engine is provided with two ignition coils and two cylinders, wherein each cylinder is provided with two spark plugs, the ignition coils and the spark plugs are in cross connection, namely the ignition coil I drives the spark plug I on the cylinder I and the spark plug III on the cylinder II, and the ignition coil II drives the spark plug II on the cylinder I and the spark plug IV on the cylinder II;

the ignition coil I is driven by the power driving unit I to realize ignition, and feeds a current signal of the ignition coil I back to the current detection unit I, the current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection of the microcontroller, and finally feeds the output state of the corresponding comparator signal 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, and a current signal of the second ignition coil is fed back to the second current detection unit, the second current detection unit inputs a corresponding comparator signal to the microcontroller, controls the output state of the corresponding comparator signal according to the ignition signal and the mode selection of the microcontroller, and finally feeds back the output state of the corresponding comparator signal to the second logic control unit and the microcontroller respectively;

the two current sensing amplifiers share a Mode selection Mode Select signal output by the data input/output module IO and current setting Limit1 and Limit2 signals output by the two digital-to-analog conversion modules DAC; aiming at each path of current sensing amplifier, the microcontroller provides two paths of input capture module IOC capture comparator signals and one path of analog-digital conversion module ADC measurement current signals.

3. The inductive dual ignition system drive circuit of an unmanned aerial vehicle engine 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 optoelectronic isolation chip isolates a driving signal Logical Drive output by the logic control unit and enhances the driving and then outputs the driving signal, when the driving signal Logical Drive is at a high level, the driving signal Logical Drive passes through a current-limiting resistor and is input by an A pin and output by a K pin of the optoelectronic isolation driving chip and drives an internal photodiode to emit light, and after receiving a light signal of the photodiode, the secondary photodiode outputs the high level driving from a Vo pin by an internal push-pull circuit;

a grid driving resistor Rg, a grid discharging resistor Rgs and a clamping diode D are integrated in the Ignition IGBT chip Q, the grid of the Ignition IGBT chip Q is connected with an output pin Vo of the photoelectric isolation chip, a collector is connected with the output voltage VS of the DC/DC boosting module through an Ignition Coil, an emitter is connected to the power ground through a current sampling resistor Rs, and the Ignition IGBT chip Q controls the on-off of the 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 the ignition coil flows through the precision current sampling resistor Rs, the voltage difference of voltage signals Rs + and Rs-at two ends of the ignition coil is positively correlated with the current, and the relationship between the voltage difference and the current satisfies the following conditions:

。

4. the inductive dual ignition system drive circuit of an unmanned aerial vehicle engine of claim 1, wherein: the current detection unit receives current signals Rs + and Rs-from the power driving unit, and the current signals are input to an amplification factor ofGCurrent sense amplifier of

And the power driving current->

And a current sampling resistance->

Satisfies the following relationship:

；

the amplified signal is a Current signal which is output by a 2 nd pin OUT of the Current sensing amplifier, and then the Current signal is output to the microcontroller; the microcontroller receives the Current signal and then according to the CurrentSampling resistor

the input anodes of two comparators in the Current sensing amplifier share a Current signal, a first comparator signal CMP1 is input into a Limit1 signal of which the cathode corresponds to a3 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 a Limit2 signal of which the negative electrode corresponds to the 9 th pin, outputs an ALERT2 signal corresponding to the 11 th pin, and outputs a second comparator signal CMP2 through the inverting buffer; when the voltage value of the Current signal is greater than the voltage value of the Limit1 signal, the first comparator signal CMP1 is at a high level, otherwise, the first comparator signal CMP1 is at a low level; when the voltage value of the Current signal is greater than the voltage value of the Limit2 signal, the second comparator signal CMP2 is at a high level, otherwise, at a low level;

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

The current sampling resistor is->

Satisfies the following conditions:

；

5. The inductive dual ignition system drive circuit of an unmanned aerial vehicle engine of claim 1, wherein: the logic control unit is provided with a multifunctional gate chip, an ignition signal Drive is input into a3 rd pin In0, a first comparator signal CMP1 is input into a1 st pin In1, and a second comparator signal CMP2 is input into a 6 th pin In2.

6. The inductive dual ignition system drive circuit of an unmanned aerial vehicle engine of claim 1, wherein: the microcontroller is internally provided with an input capture module IOC, a high-speed analog-digital conversion module ADC and a digital analog conversion module DAC, and the input capture module IOC acquires the time intervals of 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 power-on self-detection and fault diagnosis; the high-speed analog-digital conversion module ADC collects and records the primary current value of the ignition coil in real time, transmits the primary current value to an operation interface of an upper computer through a communication protocol of an 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 side of the ignition coil.

7. The inductive dual ignition system drive circuit of a drone engine of claim 1 or 6, characterized in that: 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 a high level, overcurrent turn-off protection is realized, and the specific method comprises the following steps:

the logic control unit controls the output signal Logical 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 realizes timely turn-off of the output protection ignition coil in an overcurrent state.

8. The inductive dual ignition system drive circuit of a drone engine of claim 1 or 6, characterized in that: 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, multiple ignition is realized, and the specific method comprises the following steps:

the logic control unit controls the output signal logic Drive to be low level according to the detected high levels of the ignition signal Drive, the first comparator signal CMP1 and the second comparator signal CMP2; when the primary current of the ignition coil is reduced to be between the maximum value and the minimum value, the output signal Logical Drive is still at a low level because the ALERT1 is latched to a low level, namely the first comparator signal CMP1 is latched to a high level; when the primary current of the ignition coil is lower than the minimum value, as the 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, the output signal ALERT1 of the first comparator is unlocked and restored to the high level, namely the first comparator signal CMP1 outputs a low level;

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

；

wherein ,

means that the comparator signal is delayed by a time->

9. The inductive dual ignition system drive circuit of unmanned aerial vehicle engine of claim 1 or 6, characterized in that: the microcontroller carries out fault diagnosis protection according to a comparator signal of the current detection unit, and the fault diagnosis protection method comprises the following steps:

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

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

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 moment of the ignition drive to the moment of the high output of the first comparator signal CMP1, i.e. the maximum charging pulse width ≥>

Judging that the fault diagnosis function of the microcontroller is normal together; then judging that the fault protection function of the microcontroller normally works according to low level signals of a first comparator signal CMP1 and a second comparator signal CMP2 detected after the ignition signal Drive is subsequently turned off;

and />

Are all fixed values and are first pre-calibrated>

and />

Recording in a microcontroller; the microcontroller then detects a first comparator signal CMP1, a second comparator signal CMP2 and/or a->

and />

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

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

and />

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

When the calibrated value is more than two times, judging that one of the ignition coil or the IGBT chip Q is disconnected;

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

and />

The ignition signal Drive is quickly turned off by the microcontroller when the ignition signal Drive is far smaller than a calibrated value, and if the low levels of the first comparator signal CMP1 and the second comparator signal CMP2 are 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, the ignition coil and the ignition IGBT chip Q are both judgedIn the case of short circuit, the DC/DC boost module is actively cut off to supply power, and a user is reminded to check an ignition coil and maintain the power driving unit;

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

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