Direct-current fixed-frequency ignition circuit for aero-engine and ignition control method of direct-current fixed-frequency ignition circuit

Abstract

According to the direct-current fixed-frequency ignition circuit for the aero-engine and the ignition control method of the direct-current fixed-frequency ignition circuit, in the ignition circuit, the input end of a front-stage DC-AC inverter booster circuit is connected with a direct-current power source, and the output end of the front-stage DC-AC inverter booster circuit is connected with the input end of a rear-stage high-voltage circuit; the output end of the rear-stage high-voltage circuit is connected to an ignition electric nozzle of the aero-engine and the sampling input end of the frequency stabilization control circuit, and the output end of the frequency stabilization control circuit is connected to the reset end of a control chip in the front-stage DC-AC inverter booster circuit. The direct-current fixed-frequency ignition circuit filters noise signals in direct-current electric energy through a front-stage DC-AC inverter booster circuit, converts input low-voltage direct-current electric energy into high-voltage pulse electric energy and transmits the high-voltage pulse electric energy to a rear-stage high-voltage circuit, and the high-voltage pulse electric energy is stored and released through the rear-stage high-voltage circuit so as to break down a discharge medium of an ignition electric nozzle. And sampling the high-voltage pulse electric energy released by the post-stage high-voltage circuit through the frequency stabilization control circuit, and forming a control signal for controlling the reset end of a control chip in the pre-stage DC-AC inverter booster circuit through a sampling signal. According to the technical scheme, the problems that the ignition frequency and the ignition energy of an existing fixed-frequency ignition circuit fluctuate under the influence of factors such as input voltage changes and temperature changes, so that the service life of the fixed-frequency ignition circuit is shortened, and performance is prone to decline or fail are solved. And the ignition efficiency and the working performance of the engine are influenced.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the technical field of aviation power supply, and in particular to a DC constant-frequency ignition circuit for an aviation engine and an ignition control method thereof. Background Art

[0002] At present, with the continuous development of aircraft engines, the requirements for the performance of the ignition system are also constantly increasing, especially the stability of the ignition frequency of the ignition system. While the existing fixed-frequency ignition circuit design technology has made achievements, its design still has some shortcomings and areas that need improvement.

[0003] In the existing fixed-frequency ignition circuit technology, the stability of the fixed-frequency ignition circuit is an important issue. Due to the complex and changeable working environment of the aircraft engine combustion chamber, the stability of the ignition system is extremely high. At present, some fixed-frequency ignition circuits will fluctuate in ignition frequency and ignition energy under the influence of factors such as input voltage changes and temperature changes, making the switch tubes and transformers in the DC-AC inverter boost circuit in an unstable state, and the high-voltage components in the high-voltage discharge circuit have large losses, resulting in a reduced life of the fixed-frequency ignition circuit, and it is easy to experience performance degradation or failure, thereby affecting the ignition efficiency and working performance of the engine. Summary of the invention

[0004] Purpose of the present invention: In order to solve the above-mentioned technical problems, the embodiments of the present invention provide a DC fixed-frequency ignition circuit for an aircraft engine and an ignition control method thereof, so as to solve the problem that the ignition frequency and ignition energy of the existing fixed-frequency ignition circuit fluctuate under the influence of factors such as input voltage changes and temperature changes, thereby reducing the life of the fixed-frequency ignition circuit, and being prone to performance degradation or failure, and affecting the ignition efficiency and working performance of the engine.

[0005] Technical solution of the present invention: In a first aspect, an embodiment of the present invention provides a DC constant-frequency ignition circuit for an aircraft engine, comprising: a front-stage DC-AC inverter boost circuit, a rear-stage high-voltage circuit and a frequency stabilization control circuit;

[0006] The input end of the front-stage DC-AC inverter boost circuit is connected to a DC power supply, and the output end is connected to the input end of the rear-stage high-voltage circuit. The output end of the rear-stage high-voltage circuit is respectively connected to the ignition nozzle of the aircraft engine and the sampling input end of the frequency stabilization control circuit. The output end of the frequency stabilization control circuit is connected to the reset end of the control chip in the front-stage DC-AC inverter boost circuit.

[0007] The DC constant-frequency ignition circuit is used to filter out noise signals in DC power through a front-stage DC-AC inverter boost circuit, convert the input low-voltage DC power into high-voltage pulse power and transmit it to a rear-stage high-voltage circuit, store and release the high-voltage pulse power through the rear-stage high-voltage circuit to break down the discharge medium of the ignition nozzle; and sample the high-voltage pulse power released by the rear-stage high-voltage circuit through a frequency stabilization control circuit, and form a control signal for controlling the reset terminal of the control chip in the front-stage DC-AC inverter boost circuit through the sampling signal.

[0008] Optionally, in the DC constant frequency ignition circuit for aircraft engines as described above, the front-stage DC-AC inverter boost circuit comprises: a filter, an externally excited DC-AC inverter boost control circuit and a high-frequency transformer connected in sequence;

[0009] Wherein, the filter is used to filter out noise signals with frequencies other than a specific frequency in the input DC power;

[0010] The self-excited DC-AC inverter boost control circuit and high-frequency transformer are used to convert the input low-voltage DC power into high-voltage pulse power and transmit it to the subsequent high-voltage circuit.

[0011] Optionally, in the DC constant-frequency ignition circuit for aircraft engines as described above, the post-stage high-voltage circuit comprises: two parallel energy storage and discharge channels, each energy storage and discharge channel comprises a series-connected rectifying energy storage circuit and a high-voltage discharge circuit;

[0012] The post-stage high-voltage circuit is used to rectify the high-voltage pulse electric energy through the rectifying energy storage circuit and store it in the energy storage electronic components, and release the stored energy in the form of high-voltage pulse electric energy with a specific voltage value through the high-voltage discharge circuit to break down the discharge medium of the ignition nozzle.

[0013] Optionally, in the DC fixed-frequency ignition circuit for an aircraft engine as described above, the frequency stabilization control circuit comprises a sampling circuit and a frequency stabilization circuit connected in series;

[0014] The frequency stabilization control circuit is used to collect high-voltage pulse electric energy released by the high-voltage discharge circuit through a sampling circuit for sampling, convert the collected current into a voltage signal, rectify and filter the voltage signal, and then transmit it to the frequency stabilization circuit. The frequency stabilization circuit forms a control signal through the voltage signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

[0015] Optionally, in the DC fixed-frequency ignition circuit for aircraft engines as described above, the sampling circuit in the frequency stabilization control circuit includes: a sampling resistor R25, a full-bridge rectifier circuit formed by four diodes, a resistor R26, a resistor R27, a resistor R28, a current limiting resistor R29 and a current limiting resistor R30, a capacitor C18, a capacitor C19, and an optical coupler Q6; and the optical coupler Q6 includes a photodiode and a triode controlled based on an optical signal;

[0016] Among them, the sampling resistor R25 is connected in series in the high-voltage discharge loop of the high-voltage discharge circuit, the diodes D9 and D10 connected in series are connected in parallel with the diodes D11 and D12 connected in series to form a full-bridge rectifier circuit, the positive electrode of the diode D9 and the negative electrode of the diode D10 are connected to one end of the sampling resistor R25, and the positive electrode of the diode D11 and the negative electrode of the diode D12 are connected to the other end of the sampling resistor R25, which is used to collect the high-voltage pulse current released by the high-voltage discharge loop through the full-bridge rectifier circuit. In addition, the cathodes of diode D9 and diode D11 are connected together to one end of resistor R26, the other end of resistor R26 is connected to the anode of the photodiode in the optocoupler Q6 via resistor R27 and current-limiting resistor R29, and the anodes of diode D10 and diode D12 are connected together to the cathode of the photodiode in the optocoupler Q6; one end of capacitor C18, capacitor C19 and resistor R28 are respectively connected to the cathode of the photodiode in the optocoupler Q6, the other end of capacitor C18 is connected between resistor R26 and resistor R27, the other end of capacitor C19 is connected to the rear end of resistor R27, and the other end of resistor R28 is connected to the front end of current-limiting resistor R29; one end of current-limiting resistor R30 is connected to the VCC_5V power supply, the other end of current-limiting resistor R30 is connected to the collector C of the transistor in the optocoupler Q6, and the emitter E of the transistor in the optocoupler Q6 is connected to the trigger G of the thyristor SCR2 in the frequency stabilization circuit.

[0017] Optionally, in the DC fixed-frequency ignition circuit for an aircraft engine as described above,

[0018] Each time a discharge is performed in the high-voltage discharge circuit, the sampling resistor R25 samples the high-voltage pulse current in the high-voltage discharge loop, and rectifies the voltage signal formed by the collected current signal through the full-bridge rectifier circuit. The rectified voltage signal is filtered through a secondary RC filter circuit formed by resistor R26, capacitor C18, resistor R27, and capacitor C19. Resistor R28 is a discharge resistor of capacitor C19, and resistor R29 is a current limiting resistor for protecting the photodiode in the optocoupler Q6. The sampled and filtered voltage signal is used to light up the photodiode in the optocoupler Q6 and convert it into an optical signal. The optical signal turns on the PN junction in the triode in the optocoupler Q6, and the power supply VCC_5V transmits the 5V electrical signal to the trigger pole G of the thyristor SCR2 in the frequency stabilization circuit through the current limiting resistor R30 through the collector C pole and the emitter E pole of the optocoupler Q6, thereby realizing the conversion of the high-voltage pulse electric energy in the high-voltage discharge circuit into a control signal.

[0019] Optionally, in the DC fixed-frequency ignition circuit for an aircraft engine as described above, the frequency stabilization circuit in the frequency stabilization control circuit includes: a thyristor SCR2, capacitors C9 to C12, a resistor R20, resistors R5 to R9, a transistor Q3, a transistor Q4 and a timer U3;

[0020] One end of the capacitor C12 and the resistor R20 connected in parallel is connected to the trigger pole G of the thyristor SCR2, and the other end of the capacitor C12 and the resistor R20 connected in parallel and the cathode of the thyristor SCR2 are connected to the ground; one end of the resistor R5, one end of the capacitor C11, the power supply terminal VCC of the timer U3, and the reset terminal RST of the timer U3 are connected to VCC_5V, the other end of the resistor R5 and one end of the resistor R6 are combined and connected to the discharge terminal DIS of the timer U3, the other end of the resistor R6 and one end of the capacitor C9 are combined and connected to the low level trigger terminal TRI of the timer U3 and the high level trigger terminal THR of the timer U3 respectively, and one end of the capacitor C10 is connected to the common terminal of the timer U3 CON, the other end of capacitor C9, the other end of capacitor C10, the other end of capacitor C11 and the ground terminal GND of timer U3 are connected to ground; one end of resistor R7 is connected to the output terminal OUT of timer U3, the other end of resistor R7 and one end of resistor R8 are combined and connected to the anode of thyristor SCR2, the other end of resistor R8 is connected to the base of transistor Q3, the collector of transistor Q3 is respectively connected to one end of resistor R9 and the base of transistor Q4, the emitter of transistor Q3 and the emitter of transistor Q4 are connected to ground, the other end of resistor R9 is connected to VCC_5V, and the collector of transistor Q4 is connected to the reset terminal of the timer in the previous DC-AC inverter boost circuit.

[0021] Optionally, in the DC fixed-frequency ignition circuit for an aircraft engine as described above,

[0022] The timer U3 continuously outputs a square wave control signal of a specific discharge frequency according to a preset discharge frequency. The square wave control signal is used to trigger the thyristor SCR2.

[0023] When the square wave control signal is at a high level, the anode and cathode of the thyristor SCR2 are turned on, and the square wave control signal output by the timer U3 is connected to GND after passing through the resistor R7 and the thyristor SCR2, which is used to pull down the base level of the transistor Q3 to a low level. At this time, the collector C pole and the emitter E pole of the transistor Q3 are not conducting, and the base B pole of the transistor Q4 is at a high level, so that the collector C pole and the emitter E pole of the transistor Q4 are conducting, which is used to pull down the reset end of the timer U2 in the other-excited DC-AC inverter boost circuit to a low level, thereby turning off the other-excited DC-AC inverter boost circuit and realizing primary frequency stabilization control.

[0024] Optionally, in the DC fixed-frequency ignition circuit for an aircraft engine as described above,

[0025] Based on the timer U3 continuously outputting a square wave control signal with a specific discharge frequency, when the square wave control signal output by the timer U3 is at a low level, the anode and cathode of the thyristor SCR2 are not conducting. At this time, the base of the transistor Q3 is at a high level, and the collector C pole and the emitter E pole of the transistor Q3 are conducting, which pulls down the base B pole voltage of the transistor Q4, making the base of the transistor Q4 at a low level, and the collector C pole and the emitter E pole of the transistor Q4 are not conducting, and the collector C pole of the transistor Q4 is pulled up to a high level, so as to pull the reset end of the timer U2 in the other-excited DC-AC inverter boost circuit to a high level, thereby turning on the other-excited flyback inverter boost circuit.

[0026] In a second aspect, an embodiment of the present invention further provides a control method for a DC fixed-frequency ignition circuit for an aircraft engine, wherein the DC fixed-frequency ignition circuit for an aircraft engine as described in any one of the above items is used to control the ignition of an ignition nozzle of the aircraft engine, and the control method comprises:

[0027] The noise signal with frequency other than the specific frequency in the input DC power is filtered out through the front-stage DC-AC inverter boost circuit, and the input low-voltage DC power is converted into high-voltage pulse power and transmitted to the rear-stage high-voltage circuit;

[0028] The input high-voltage pulse electric energy is rectified and stored in the energy storage electronic components through the subsequent high-voltage circuit, and the stored energy is released as high-voltage pulse electric energy of a specific voltage value to break through the discharge medium of the ignition nozzle;

[0029] The high-voltage pulse electric energy released by the subsequent high-voltage circuit is sampled through the frequency stabilization control circuit, and the sampled current signal is converted into a voltage signal for rectification and filtering. The processed voltage signal is used to form a control signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

[0030] Beneficial effects of the present invention: A DC fixed-frequency ignition circuit and an ignition control method for an aircraft engine provided by an embodiment of the present invention require that the spark frequency of the fixed-frequency ignition circuit under full voltage input conditions is (3 to 5) Hz. The embodiment of the present invention designs a simple and reliable frequency stabilization control circuit, and controls the on and off states of the triode through a control signal provided by an optocoupler in the frequency stabilization control circuit, thereby controlling the charging and discharging time of the front-stage DC-AC inverter boost circuit in the fixed-frequency ignition circuit, and finally achieving control of the discharge frequency of the ignition circuit. Under input voltage conditions with a large input range of (8 to 34) VDC, a stable frequency output can be achieved. The ignition circuit provided by the present invention requires fewer electronic components and a relatively simple control logic, and has the advantages of low cost, stable output spark frequency, long ignition system life, and high reliability.

[0031] The DC constant-frequency ignition circuit provided in the embodiment of the present invention has been used in a variety of newly developed model ignition systems. At present, the ignition circuit has been tested and verified with multiple models of ignition systems. The ignition circuit achieves a spark frequency tolerance value of 0.5Hz under the full input voltage condition of (8~34), and the use effect is good; in addition, since the main components of the frequency stabilization control circuit of the present invention are few and simple, the present invention also has the effects of low cost and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0033] Figure 1 A circuit block diagram of a DC fixed-frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the circuit structure of a DC fixed-frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of a square wave control signal output by a timer U2 in a front-stage DC-AC inverter boost circuit in an embodiment of the present invention;

[0036] Figure 4Schematic diagram of a high-voltage discharge signal output by a subsequent high-voltage discharge circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0038] The above background technology has explained that the existing fixed-frequency ignition circuit will cause the ignition frequency and ignition energy to fluctuate under the influence of factors such as input voltage changes and temperature changes, thereby reducing the life of the fixed-frequency ignition circuit and making it prone to performance degradation or failure, thereby affecting the ignition efficiency and working performance of the engine.

[0039] In addition, existing fixed-frequency ignition circuit control methods are often more complicated, requiring the use of multiple control units and complex circuit structures to achieve precise control of the ignition frequency and ignition energy, which not only increases the complexity and cost of the fixed-frequency ignition circuit, but also reduces the maintainability of the fixed-frequency ignition circuit.

[0040] In order to solve the above problems, an embodiment of the present invention provides a DC fixed-frequency ignition circuit and an ignition control method for an aircraft engine. Through a unique design and control method, it aims to achieve a stable output of the ignition frequency, and is committed to adopting a simpler and more efficient control strategy. By optimizing the circuit design, the complexity and cost of the fixed-frequency ignition circuit are reduced, and the reliability and maintainability of the system are improved.

[0041] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0042] Figure 1 The circuit block diagram of a DC fixed frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention. Figure 1 As shown, the DC constant-frequency ignition circuit for aircraft engines provided by the embodiment of the present invention mainly includes three circuit structures: a front-stage DC-AC inverter boost circuit, a rear-stage high-voltage circuit and a frequency stabilization control circuit.

[0043] like Figure 1 As shown, in the DC fixed-frequency ignition circuit provided by the embodiment of the present invention, the input end of the front-stage DC-AC inverter boost circuit is connected to a DC power supply, and the output end is connected to the input end of the rear-stage high-voltage circuit. The output end of the rear-stage high-voltage circuit is respectively connected to the ignition nozzle of the aircraft engine and the sampling input end of the frequency stabilization control circuit, and the output end of the frequency stabilization control circuit is connected to the reset end of the control chip in the front-stage DC-AC inverter boost circuit.

[0044] The DC constant-frequency ignition circuit provided in the embodiment of the present invention is used to filter out noise signals in DC power through a front-stage DC-AC inverter boost circuit, convert the input low-voltage DC power into high-voltage pulse power and transmit it to a rear-stage high-voltage circuit, store and release the high-voltage pulse power through the rear-stage high-voltage circuit to break down the discharge medium of the ignition nozzle; and sample the high-voltage pulse power released by the rear-stage high-voltage circuit through a frequency stabilization control circuit, and form a control signal for controlling the reset terminal of the control chip in the front-stage DC-AC inverter boost circuit through the sampling signal.

[0045] like Figure 1 As shown, the front-stage DC-AC inverter boost circuit in the embodiment of the present invention includes: a filter, an externally excited DC-AC inverter boost control circuit and a high-frequency transformer connected in sequence; in the front-stage DC-AC inverter boost circuit, the filter is used to filter out noise signals with frequencies other than a specific frequency in the input DC power, which can effectively eliminate or reduce the noise signals that have a negative impact on the power supply circuit, and can weaken the radiation noise generated by the high-frequency pulse when the ignition circuit is working, thereby ensuring the stability of the function and performance of the ignition circuit, and the externally excited DC-AC inverter boost control circuit and the high-frequency transformer convert the input low-voltage DC power into high-voltage pulse power, and transmit it to the subsequent high-voltage circuit.

[0046] like Figure 1 As shown, the post-stage high-voltage circuit in the embodiment of the present invention comprises: two parallel energy storage and discharge channels, each of which comprises a series-connected rectifying energy storage circuit and a high-voltage discharge circuit;

[0047] The post-stage high-voltage circuit rectifies the high-voltage pulse electric energy through the rectifier energy storage circuit and stores it in the energy storage electronic components, and releases the stored energy in the form of high-voltage pulse electric energy with a specific voltage value through the high-voltage discharge circuit to break down the discharge medium of the ignition nozzle.

[0048] like Figure 1 As shown, the frequency stabilization control circuit in the embodiment of the present invention includes a sampling circuit and a frequency stabilization circuit connected in series.

[0049] The frequency stabilization control circuit samples the high-voltage pulse electric energy released by the high-voltage discharge circuit through a sampling circuit (the sampled current is converted into a voltage signal itself), and transmits the sampled voltage signal to the frequency stabilization circuit after rectification and filtering. The frequency stabilization circuit forms a control signal through the voltage signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

[0050] The circuit structure and implementation principle of the DC constant-frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention are described as follows.

[0051] like Figure 2 , which is a schematic diagram of the circuit structure of a DC fixed-frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention.

[0052] In order to realize the function and performance of the fixed frequency ignition circuit provided by the present invention, the circuit structure diagram is designed as shown in the following figure: Figure 2 As shown, it is mainly composed of a front-stage DC-AC inverter boost circuit (mainly including an independently excited DC-AC inverter boost control circuit), a rear-stage high-voltage circuit, and a frequency stabilization control circuit. The frequency stabilization control part is mainly analyzed, as described below.

[0053] (1) Frequency stabilization control circuit

[0054] It has been explained above that the frequency stabilization control circuit is composed of a sampling circuit and a frequency stabilization circuit. The structures and functions of the sampling circuit and the frequency stabilization circuit are described as follows:

[0055] 1.1. The sampling circuit includes: a sampling resistor R25, a full-bridge rectifier circuit formed by four diodes (D9-D12), resistors (resistor R26, resistor R27, resistor R28, current limiting resistor R29 and current limiting resistor R30), capacitor C18, capacitor C19, and an optical coupler Q6 (for example, GH302-1); the optical coupler Q6 includes a photodiode and a transistor controlled based on an optical signal.

[0056] like Figure 2As shown, in the sampling circuit, the sampling resistor R25 is connected in series in the high-voltage discharge loop of the high-voltage discharge circuit, the diodes D9 and D10 connected in series are connected in parallel with the diodes D11 and D12 connected in series to form a full-bridge rectifier circuit, the positive electrode of the diode D9 and the negative electrode of the diode D10 are connected to one end of the sampling resistor R25, and the positive electrode of the diode D11 and the negative electrode of the diode D12 are connected to the other end of the sampling resistor R25, which is used to collect the high-voltage pulse current released by the high-voltage discharge loop through the full-bridge rectifier circuit. In addition, the cathodes of diode D9 and diode D11 are connected together to one end of resistor R26, the other end of resistor R26 is connected to the anode of the photodiode in the optocoupler Q6 through resistor R27 and current-limiting resistor R29, and the anodes of diode D10 and diode D12 are connected together to the cathode of the photodiode in the optocoupler Q6; one end of capacitor C18, capacitor C19 and resistor R28 are respectively connected to the cathode of the photodiode in the optocoupler Q6, the other end of capacitor C18 is connected between resistor R26 and resistor R27, the other end of capacitor C19 is connected to the rear end of resistor R27, and the other end of resistor R28 is connected to the front end of current-limiting resistor R29; one end of current-limiting resistor R30 is connected to the VCC_5V power supply, the other end of current-limiting resistor R30 is connected to the collector (C pole) of the transistor in the optocoupler Q6, and the emitter (E pole) of the transistor in the optocoupler Q6 is connected to the trigger pole (G pole) of the thyristor SCR2 in the frequency stabilization circuit.

[0057] The working principle of the sampling circuit is as follows: each time a discharge is performed in the high-voltage discharge circuit, the sampling resistor R25 samples the high-voltage pulse current in the high-voltage discharge loop, and the voltage signal formed by the collected current signal is rectified by the full-bridge rectifier circuit (D9-D12). The rectified voltage signal is filtered by the secondary RC filter circuit formed by the resistor R26, the capacitor C18, the resistor R27, and the capacitor C19. The resistor R28 is the discharge resistor of the capacitor C19, and the resistor R29 is the current limiting resistor, which is used to protect the photodiode in the optocoupler Q6. The sampled and filtered voltage signal is used to light up the photodiode in the optocoupler Q6 and convert it into an optical signal. The optical signal turns on the PN junction in the triode in the optocoupler Q6 (i.e., the emitter 3 and the collector 4 pins). The power supply VCC_5V transmits the 5V electrical signal to the trigger pole G of the thyristor SCR2 in the frequency stabilization circuit through the current limiting resistor R30 through the collector C pole and the emitter E pole of the optocoupler Q6, thereby realizing the conversion of the high-voltage pulse electric energy in the high-voltage discharge circuit into a control signal.

[0058] 1.2, the frequency stabilization control circuit includes: thyristor SCR2, capacitors C9 to C12, resistor R20, resistors R5 to R9, transistor Q3, transistor Q4 and timer U3.

[0059] The following table 1 is the trigger table of thyristor SCR2:

[0060] Table 1 Triggering table of thyristor SCR2

[0061] Trigger level Anode level SCR on / off Triggering very high level / Conductivity Trigger very low level Anode high level Conductivity Trigger very low level Anode low level closure

[0062] like Figure 2 As shown, in the frequency stabilization control circuit, one end of the parallel capacitor C12 and the resistor R20 is connected to the trigger pole G of the thyristor SCR2, and the other end of the parallel capacitor C12 and the resistor R20 and the cathode of the thyristor SCR2 are connected to the ground; one end of the resistor R5, one end of the capacitor C11 and the power supply terminal VCC (pin 8) of the timer U3, and the reset terminal RST (pin 4) of the timer U3 are connected to VCC_5V, the other end of the resistor R5 and one end of the resistor R6 are combined and connected to the discharge terminal DIS (pin 7) of the timer U3, the other end of the resistor R6 and one end of the capacitor C9 are combined and connected to the low level trigger terminal TRI (pin 2) of the timer U3 and the high level trigger terminal THR (pin 6) of the timer U3 respectively, and one end of the capacitor C10 is connected to the constant The common terminal CON (pin 5) of the timer U3, the other end of the capacitor C9, the other end of the capacitor C10, the other end of the capacitor C11 and the ground terminal GND (pin 1) of the timer U3 are connected to the ground; one end of the resistor R7 is connected to the output terminal OUT (pin 3) of the timer U3, the other end of the resistor R7 and one end of the resistor R8 are combined and connected to the anode of the thyristor SCR2, the other end of the resistor R8 is connected to the base of the transistor Q3, the collector of the transistor Q3 is respectively connected to one end of the resistor R9 and the base of the transistor Q4, the emitter of the transistor Q3 and the emitter of the transistor Q4 are connected to the ground, the other end of the resistor R9 is connected to VCC_5V, and the collector of the transistor Q4 is connected to the reset terminal (pin 4) of the timer in the previous DC-AC inverter boost circuit.

[0063] The working principle of the frequency stabilization control circuit is as follows: the timer U3 continuously outputs a square wave control signal of a specific discharge frequency according to the discharge frequency specified in the technical requirements. The square wave control signal is used to trigger the thyristor SCR2. When the square wave control signal is at a high level, the anode and cathode of the thyristor SCR2 are turned on. The square wave control signal output by the timer U3 is connected to GND after passing through the resistor R7 and the thyristor SCR2, and is used to pull down the base level of the transistor Q3 to a low level, so that the collector C pole and the emitter E pole of the transistor Q3 are not turned on. At this time, the base B pole of the transistor Q4 is at a high level, so that the collector C pole and the emitter E pole of the transistor Q4 are turned on (the C pole of Q4 is connected to the reset terminal of the timer U2, and the collector C pole of Q4 is at a low level at this time), and is used to pull down the reset terminal (pin 4) of the timer U2 in the other-excited DC-AC inverter boost circuit to a low level, thereby turning off the other-excited DC-AC inverter boost circuit to achieve a primary frequency stabilization control.

[0064] Based on the timer U3 continuously outputting a square wave control signal with a specific discharge frequency, when the square wave control signal output by the timer U3 is at a low level, the anode and cathode of the thyristor SCR2 are not conducting. At this time, the base of the transistor Q3 is at a high level, and the collector C pole and the emitter E pole of the transistor Q3 are conducting, which pulls down the base B pole voltage of the transistor Q4, so that the base of the transistor Q4 is at a low level, and the collector C pole and the emitter E pole of the transistor Q4 are not conducting, and the collector C pole of the transistor Q4 is pulled up to a high level (because the C pole of Q4 is connected to the reset end of U2), so as to pull the reset end of the timer U2 in the other-excited DC-AC inverter boost circuit to a high level, thereby turning on the other-excited flyback inverter boost circuit.

[0065] The above-mentioned switching on and off of the self-excited DC-AC inverter boost circuit is realized through the frequency stabilization control circuit, that is, the frequency stabilization control is realized.

[0066] (2) Circuit waveform simulation, taking the output frequency of 4 Hz as an example:

[0067] 2.1, Timer U2 output waveform

[0068] The output terminal (pin 3) of the timer U2 in the previous DC-AC inverter boost circuit is a square wave control signal with a frequency of 4Hz and a duty cycle of 90%. Figure 3 , which is a schematic diagram of a square wave control signal output by a timer U2 in a front-stage DC-AC inverter boost circuit in an embodiment of the present invention.

[0069] 2.2, Output high voltage discharge signal

[0070] like Figure 4 , which is a schematic diagram of a high-voltage discharge signal output by a subsequent high-voltage discharge circuit in an embodiment of the present invention. Figure 4 The figure shows the frequency of the high-voltage pulse electrical signal (i.e., the spark frequency) of the subsequent high-voltage discharge circuit after being controlled by the frequency stabilization control circuit. It can be seen that the high-voltage discharge waveform is a 4Hz high-voltage pulse.

[0071] (3) Experimental verification

[0072] In order to verify that the DC fixed-frequency ignition circuit provided by the present invention can achieve a stable frequency output of 4Hz (the frequency can be set according to the parameters of the timer U2, and 4Hz is used as an example in the embodiment of the present invention) output spark frequency under a wide input voltage range (8-34) VDC, an experiment is conducted to verify that the spark frequency at the discharge end of the ignition nozzle is measured by a frequency meter by setting different input voltages. The average value is taken by measuring three times under the same input voltage (two decimal places are retained). The test results are shown in Table 2 below:

[0073] Table 2 Spark frequency at different voltages

[0074]

[0075] It can be concluded from the above test results that under different input voltage conditions (8-34) VDC, the output spark discharge frequency is stable at about 4 Hz, proving that the DC constant-frequency ignition circuit provided in the embodiment of the present invention achieves the purpose of the invention.

[0076] Based on the DC fixed-frequency ignition circuit for an aircraft engine provided by an embodiment of the present invention, an embodiment of the present invention further provides a control method for the DC fixed-frequency ignition circuit for an aircraft engine, wherein the DC fixed-frequency ignition circuit for an aircraft engine provided by any of the above embodiments of the present invention is used to control the ignition of an ignition nozzle of the aircraft engine, and the control method comprises:

[0077] The noise signal with frequency other than the specific frequency in the input DC power is filtered out through the front-stage DC-AC inverter boost circuit, and the input low-voltage DC power is converted into high-voltage pulse power and transmitted to the rear-stage high-voltage circuit;

[0078] The input high-voltage pulse electric energy is rectified and stored in the energy storage electronic components through the subsequent high-voltage circuit, and the stored energy is released as high-voltage pulse electric energy of a specific voltage value to break through the discharge medium of the ignition nozzle;

[0079] The high-voltage pulse electric energy released by the subsequent high-voltage circuit is sampled through the frequency stabilization control circuit, and the sampled current signal is converted into a voltage signal for rectification and filtering. The processed voltage signal is used to form a control signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

[0080] The DC fixed-frequency ignition circuit and ignition control method for aircraft engines provided in the embodiment of the present invention require that the spark frequency of the fixed-frequency ignition circuit under full voltage input conditions is (3-5) Hz. The embodiment of the present invention designs a simple and reliable frequency stabilization control circuit, and controls the on and off states of the triode through a control signal provided by an optocoupler in the frequency stabilization control circuit, thereby controlling the charge and discharge time of the front-stage DC-AC inverter boost circuit in the fixed-frequency ignition circuit, and finally realizing the control of the discharge frequency of the ignition circuit. Under the condition of an input voltage of (8-34) VDC with a large input range, a stable frequency output can be achieved. The ignition circuit provided by the present invention requires fewer electronic components and a relatively simple control logic, and has the advantages of low cost, stable output spark frequency, long ignition system life, and high reliability.

[0081] The DC constant-frequency ignition circuit provided in the embodiment of the present invention has been used in a variety of newly developed model ignition systems. At present, the ignition circuit has been tested and verified with multiple models of ignition systems. The ignition circuit achieves a spark frequency tolerance value of 0.5Hz under the full input voltage condition of (8~34), and the use effect is good; in addition, since the main components of the frequency stabilization control circuit of the present invention are few and simple, the present invention also has the effects of low cost and high reliability.

[0082] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A DC constant frequency ignition circuit for an aircraft engine, characterized in that: include: Front-stage DC-AC inverter boost circuit, rear-stage high-voltage circuit and frequency stabilization control circuit; The input end of the front-stage DC-AC inverter boost circuit is connected to a DC power supply, and the output end is connected to the input end of the rear-stage high-voltage circuit. The output end of the rear-stage high-voltage circuit is respectively connected to the ignition nozzle of the aircraft engine and the sampling input end of the frequency stabilization control circuit. The output end of the frequency stabilization control circuit is connected to the reset end of the control chip in the front-stage DC-AC inverter boost circuit. The DC constant-frequency ignition circuit is used to filter out noise signals in DC power through a front-stage DC-AC inverter boost circuit, convert the input low-voltage DC power into high-voltage pulse power and transmit it to a rear-stage high-voltage circuit, store and release the high-voltage pulse power through the rear-stage high-voltage circuit to break down the discharge medium of the ignition nozzle; and sample the high-voltage pulse power released by the rear-stage high-voltage circuit through a frequency stabilization control circuit, and form a control signal for controlling the reset terminal of the control chip in the front-stage DC-AC inverter boost circuit through the sampling signal.

2. The DC constant frequency ignition circuit for aircraft engines according to claim 1, characterized in that: The front-stage DC-AC inverter boost circuit comprises: a filter, an externally excited DC-AC inverter boost control circuit and a high-frequency transformer connected in sequence; Wherein, the filter is used to filter out noise signals with frequencies other than a specific frequency in the input DC power; The self-excited DC-AC inverter boost control circuit and high-frequency transformer are used to convert the input low-voltage DC power into high-voltage pulse power and transmit it to the subsequent high-voltage circuit.

3. The DC constant frequency ignition circuit for aircraft engines according to claim 2, characterized in that: The post-stage high-voltage circuit comprises: two parallel energy storage and discharge channels, each of which comprises a series-connected rectifying energy storage circuit and a high-voltage discharge circuit; The post-stage high-voltage circuit is used to rectify the high-voltage pulse electric energy through the rectifying energy storage circuit and store it in the energy storage electronic components, and release the stored energy in the form of high-voltage pulse electric energy with a specific voltage value through the high-voltage discharge circuit to break down the discharge medium of the ignition nozzle.

4. The DC constant frequency ignition circuit for aircraft engines according to claim 3, characterized in that: The frequency stabilization control circuit comprises a sampling circuit and a frequency stabilization circuit connected in series; The frequency stabilization control circuit is used to collect high-voltage pulse electric energy released by the high-voltage discharge circuit through a sampling circuit for sampling, convert the collected current into a voltage signal, rectify and filter the voltage signal, and then transmit it to the frequency stabilization circuit. The frequency stabilization circuit forms a control signal through the voltage signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

5. The DC constant frequency ignition circuit for aircraft engines according to claim 4, characterized in that: The sampling circuit in the frequency stabilization control circuit includes: a sampling resistor R25, a full-bridge rectifier circuit formed by four diodes, a resistor R26, a resistor R27, a resistor R28, a current limiting resistor R29 and a current limiting resistor R30, a capacitor C18, a capacitor C19, and an optical coupler Q6; and the optical coupler Q6 includes a photodiode and a triode controlled based on an optical signal; Among them, the sampling resistor R25 is connected in series in the high-voltage discharge loop of the high-voltage discharge circuit, the diodes D9 and D10 connected in series are connected in parallel with the diodes D11 and D12 connected in series to form a full-bridge rectifier circuit, the positive electrode of the diode D9 and the negative electrode of the diode D10 are connected to one end of the sampling resistor R25, and the positive electrode of the diode D11 and the negative electrode of the diode D12 are connected to the other end of the sampling resistor R25, which is used to collect the high-voltage pulse current released by the high-voltage discharge loop through the full-bridge rectifier circuit; the negative electrodes of the diodes D9 and D11 are connected to one end of the resistor R26 after being combined, and the other end of the resistor R26 is connected to the photoelectric diode in the optocoupler Q6 after being connected through the resistor R27 and the current limiting resistor R29. The positive electrode of the diode D10 and the positive electrode of the diode D12 are connected to the negative electrode of the photodiode in the optocoupler Q6; one end of the capacitor C18, the capacitor C19 and the resistor R28 are respectively connected to the negative electrode of the photodiode in the optocoupler Q6, the other end of the capacitor C18 is connected between the resistor R26 and the resistor R27, the other end of the capacitor C19 is connected to the rear end of the resistor R27, and the other end of the resistor R28 is connected to the front end of the current limiting resistor R29; one end of the current limiting resistor R30 is connected to the VCC_5V power supply, and the other end of the current limiting resistor R30 is connected to the collector C electrode of the transistor in the optocoupler Q6, and the emitter E electrode of the transistor in the optocoupler Q6 is connected to the trigger electrode G electrode of the thyristor SCR2 in the frequency stabilization circuit.

6. The DC constant frequency ignition circuit for aircraft engines according to claim 5, characterized in that: Each time a discharge is performed in the high-voltage discharge circuit, the sampling resistor R25 samples the high-voltage pulse current in the high-voltage discharge loop, and rectifies the voltage signal formed by the collected current signal through the full-bridge rectifier circuit. The rectified voltage signal is filtered through a secondary RC filter circuit formed by resistor R26, capacitor C18, resistor R27, and capacitor C19. Resistor R28 is a discharge resistor of capacitor C19, and resistor R29 is a current limiting resistor for protecting the photodiode in the optocoupler Q6. The sampled and filtered voltage signal is used to light up the photodiode in the optocoupler Q6 and convert it into an optical signal. The optical signal turns on the PN junction in the triode in the optocoupler Q6, and the power supply VCC_5V transmits the 5V electrical signal to the trigger pole G of the thyristor SCR2 in the frequency stabilization circuit through the current limiting resistor R30 through the collector C pole and the emitter E pole of the optocoupler Q6, thereby realizing the conversion of the high-voltage pulse electric energy in the high-voltage discharge circuit into a control signal.

7. The DC constant frequency ignition circuit for aircraft engines according to claim 5, characterized in that: The frequency stabilization circuit in the frequency stabilization control circuit includes: a thyristor SCR2, capacitors C9 to C12, a resistor R20, resistors R5 to R9, a transistor Q3, a transistor Q4 and a timer U3; One end of the capacitor C12 and the resistor R20 connected in parallel is connected to the trigger pole G of the thyristor SCR2, and the other end of the capacitor C12 and the resistor R20 connected in parallel and the cathode of the thyristor SCR2 are connected to the ground; one end of the resistor R5, one end of the capacitor C11, the power supply terminal VCC of the timer U3, and the reset terminal RST of the timer U3 are connected to VCC_5V, the other end of the resistor R5 and one end of the resistor R6 are combined and connected to the discharge terminal DIS of the timer U3, the other end of the resistor R6 and one end of the capacitor C9 are combined and connected to the low level trigger terminal TRI of the timer U3 and the high level trigger terminal THR of the timer U3 respectively, and one end of the capacitor C10 is connected to the common terminal of the timer U3 CON, the other end of capacitor C9, the other end of capacitor C10, the other end of capacitor C11 and the ground terminal GND of timer U3 are connected to ground; one end of resistor R7 is connected to the output terminal OUT of timer U3, the other end of resistor R7 and one end of resistor R8 are combined and connected to the anode of thyristor SCR2, the other end of resistor R8 is connected to the base of transistor Q3, the collector of transistor Q3 is respectively connected to one end of resistor R9 and the base of transistor Q4, the emitter of transistor Q3 and the emitter of transistor Q4 are connected to ground, the other end of resistor R9 is connected to VCC_5V, and the collector of transistor Q4 is connected to the reset terminal of the timer in the previous DC-AC inverter boost circuit.

8. The DC constant frequency ignition circuit for aircraft engines according to claim 7, characterized in that: The timer U3 continuously outputs a square wave control signal of a specific discharge frequency according to a preset discharge frequency. The square wave control signal is used to trigger the thyristor SCR2. When the square wave control signal is at a high level, the anode and cathode of the thyristor SCR2 are turned on, and the square wave control signal output by the timer U3 is connected to GND after passing through the resistor R7 and the thyristor SCR2, which is used to pull down the base level of the transistor Q3 to a low level. At this time, the collector C pole and the emitter E pole of the transistor Q3 are not conducting, and the base B pole of the transistor Q4 is at a high level, so that the collector C pole and the emitter E pole of the transistor Q4 are conducting, which is used to pull down the reset end of the timer U2 in the other-excited DC-AC inverter boost circuit to a low level, thereby turning off the other-excited DC-AC inverter boost circuit and realizing primary frequency stabilization control.

9. The DC constant frequency ignition circuit for aircraft engines according to claim 8, characterized in that: Based on the timer U3 continuously outputting a square wave control signal with a specific discharge frequency, when the square wave control signal output by the timer U3 is at a low level, the anode and cathode of the thyristor SCR2 are not conducting. At this time, the base of the transistor Q3 is at a high level, and the collector C pole and the emitter E pole of the transistor Q3 are conducting, which pulls down the base B pole voltage of the transistor Q4, making the base of the transistor Q4 at a low level, and the collector C pole and the emitter E pole of the transistor Q4 are not conducting, and the collector C pole of the transistor Q4 is pulled up to a high level, so as to pull the reset end of the timer U2 in the other-excited DC-AC inverter boost circuit to a high level, thereby turning on the other-excited flyback inverter boost circuit.

10. A control method for a DC fixed frequency ignition circuit of an aircraft engine, characterized in that: The ignition nozzle of an aircraft engine is controlled by using the DC constant frequency ignition circuit for an aircraft engine as claimed in any one of claims 1 to 9, and the control method includes: The noise signal with frequency other than the specific frequency in the input DC power is filtered out through the front-stage DC-AC inverter boost circuit, and the input low-voltage DC power is converted into high-voltage pulse power and transmitted to the rear-stage high-voltage circuit; The input high-voltage pulse electric energy is rectified and stored in the energy storage electronic components through the subsequent high-voltage circuit, and the stored energy is released as high-voltage pulse electric energy of a specific voltage value to break through the discharge medium of the ignition nozzle; The high-voltage pulse electric energy released by the subsequent high-voltage circuit is sampled through the frequency stabilization control circuit, and the sampled current signal is converted into a voltage signal for rectification and filtering. The processed voltage signal is used to form a control signal to control the reset end of the control chip in the previous DC-AC inverter boost circuit, thereby achieving stable output of the ignition frequency.

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