Electronic ignition circuit for setting frequency

Abstract

The application belongs to the field of aero-engine ignition, and particularly relates to an electronic type it excitation frequency ignition circuit. The electronic type it excitation frequency ignition circuit comprises a filter module, a voltage stabilizing module, a time base module, a sampling control module, a voltage boosting module, a rectification energy storage module and a discharging module which are connected in sequence, wherein the filter module receives power input, and the discharging module performs high-voltage pulse output.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine ignition, specifically relating to an electronic self-excited fixed-frequency ignition circuit. Background Technology

[0002] Currently, the ignition circuits in traditional aero-engine electronic ignition systems typically use self-excited ignition circuits. Their function is to invert the input DC power into AC power, then boost and rectify it before outputting it in pulse form. Self-excited ignition circuits have a simple structure and use few electronic components. However, when the input voltage range is wide, the frequency of the output pulses varies significantly. For example, with an input voltage of 16VDC, the ignition system outputs a pulse frequency of 1.5Hz and a power of approximately 10W; with an input voltage of 32VDC, the output pulse frequency is 5Hz and the power is approximately 30W. Currently, fixed-frequency self-excited ignition circuits have also been designed, but these use more components, have a complex structure, and are larger and heavier. Engine manufacturers require ignition systems that are as small and lightweight as possible, while also generating a higher frequency at low voltage inputs and maintaining stable power across the entire voltage range. Summary of the Invention

[0003] Summary of the invention: An electronic self-excited fixed-frequency ignition circuit is provided to ensure stable discharge frequency and constant power.

[0004] Technical solution:

[0005] An electronic self-excited fixed-frequency ignition circuit includes a filter module, a voltage regulator module, a time base module, a sampling control module, a boost module, a rectifier energy storage module, and a discharge module connected in sequence. The filter module receives power input, and the discharge module outputs a high-voltage pulse.

[0006] Furthermore, the voltage regulator module includes a three-terminal regulator U1, diodes D1 to D3, and capacitors C1 to C4. The input terminal of the three-terminal regulator U1 is connected to one end of capacitor C1, the cathode of diode D2, one end of capacitor C2, the cathode of diode D1, and one output terminal of the filter. The output terminal of the three-terminal regulator U1 is connected to one end of capacitor C3, the anode of diode D1, one end of capacitor C4, and the cathode of diode D3. The voltage regulator terminal of the three-terminal regulator U1 is connected to the other end of capacitor C1, the other end of capacitor C2, the anode of diode D2, the other end of capacitor C3, the anode of diode D3, the other end of capacitor C4, and the other output terminal of the filter.

[0007] Furthermore, the time base module includes: a time base circuit U2, resistors R1 to R4, and capacitors C5 to C7. One end of resistor R1 is connected to one end of resistor R2 and the power supply pin of time base circuit U2; the other end of resistor R1 is connected to one end of capacitor C5 and the reset pin of time base circuit U2; the other end of resistor R2 is connected to one end of resistor R3 and the discharge pin of time base circuit U2; the other end of capacitor C5 is connected to one end of capacitor C6, one end of capacitor C7, and the ground pin of time base circuit U2; the other end of resistor R3 is connected to the other end of capacitor C6, pin 6 of time base circuit U2, and the trigger pin of time base circuit U2; the other end of capacitor C7 is connected to the control pin of time base circuit U2; and one end of resistor R4 is connected to the output pin of time base circuit U2.

[0008] Furthermore, the sampling control module includes a comparator U3, a thyristor SCR1, a diode D6, resistors R5 to R10, and a capacitor C8. The positive input terminal of comparator U3 is connected to one end of resistor R7 and one end of capacitor C8; the negative input terminal of comparator U3 is connected to the adjustment terminal of adjustable resistor R8; the output terminal of comparator U3 is connected to one end of resistor R5 and the negative terminal of diode D6; the positive terminal of thyristor SCR1 is connected to the other end of resistor R4, one end of resistor R9, and the gate of field-effect transistor Q1; the negative terminal of thyristor SCR1 is connected to the positive terminal of diode D6, one end of resistor R8, the other end of resistor R9, one end of resistor R10, and the other end of capacitor C8; the other end of resistor R5 is connected to the power supply pin of timer circuit U2 and one end of resistor R6; the other end of resistor R6 is connected to the other end of resistor R8; and the other end of resistor R7 is connected to the other end of resistor R10.

[0009] Furthermore, the boost module includes diodes D4 and D5 and transformer T1, wherein the anode of diode D4 is connected to the cathode of diode D5; the cathode of diode D4 is connected to one output terminal of the filter and one input terminal of transformer T1; and the cathode of diode D5 is connected to the drain of field-effect transistor Q1 and the other input terminal of transformer T1.

[0010] Furthermore, the rectifier energy storage module includes a silicon stack D7 and a capacitor C9, wherein the positive terminal of the silicon stack D7 is connected to one output terminal of the transformer T1; and the two ends of the capacitor C9 are connected to the negative terminal of the silicon stack D7 and the other output terminal of the transformer T1, respectively.

[0011] Furthermore, the discharge module includes a discharge tube V1 and a resistor R11, wherein one end of the discharge tube V1 is connected to the negative terminal of the silicon stack D7; the other end of the discharge tube V1 is connected to one end of the resistor R11; and the other end of the resistor R11 is connected to the other output terminal of the transformer T1.

[0012] Furthermore, the three-terminal voltage regulator U1 is a CW78M12K.

[0013] Beneficial effects:

[0014] This invention proposes an electronic self-excited fixed-frequency ignition circuit. By using a timer module to output a fixed frequency, a fixed switching frequency is provided for the field-effect transistor. A sampling feedback module modulates the pulse width of the switching frequency under different input voltage conditions to ensure a constant power output to the high-voltage circuit. When the input voltage is low, the duty cycle of the timer module is increased to improve the pulse width; when the input voltage is high, the duty cycle of the timer module is decreased to reduce the pulse width, thereby ensuring a stable discharge frequency and constant power. Attached Figure Description

[0015] Figure 1 This is a block diagram of an electronic self-excited fixed-frequency ignition circuit.

[0016] Figure 2 It is an electronic self-excited fixed-frequency ignition circuit. Detailed Implementation

[0017] This invention provides an electronic self-excited fixed-frequency ignition circuit, the circuit block diagram of which is shown below. Figure 1 As shown, the circuit principle is as follows: Figure 2 As shown, the circuit consists of a low-voltage circuit and a high-voltage circuit. The low-voltage circuit comprises a filter module, a voltage regulator module, a timer module, and a sampling control module. The high-voltage circuit comprises a boost module, a rectifier energy storage module, and a discharge module. The three-terminal voltage regulator U1, diodes D1-D3, and capacitors C1-C4 form the voltage regulator module, providing a stable constant voltage to the timer module and the sampling control module regardless of changes in the power supply voltage. The timer circuit U2, resistors R1-R4, and capacitors C5-C7 form the timer module, providing a fixed switching frequency to the field-effect transistor Q1. The comparator U3, thyristor SCR1, diode D6, and resistors R5-R10 form the sampling control module. When the current in the field-effect transistor Q1 increases to a preset value, the voltage across the sampling resistor R10 reaches a preset value, turning on the thyristor SCR1 through the voltage comparator U3, forming a PWM pulse width modulation to control the conduction time of the field-effect transistor Q1. Diodes D4, D5, and T1 form a boost module, which boosts the power supply voltage to the high voltage required by the high-voltage circuit. Silicon stack D7 and capacitor C9 form a rectifier energy storage module, which stores the boosted electrical energy in the capacitor. Discharge tube V1 and capacitor R11 form a discharge module. When the voltage across capacitor C9 reaches the discharge voltage of discharge tube V1, discharge tube V1 conducts, and the electrical energy in capacitor C9 is released to the next stage.

[0018] The main components selected for the circuit are as follows:

[0019] a) Three-terminal voltage regulator U1 (CW78M12K);

[0020] b) The left end of the timer circuit U2 (JB555) is arranged from top to bottom as follows: (4 / 7 / 6 / 2 / 5). The upper end 8 is connected to the power supply VCC, the lower end 1 is grounded, and the right end 3 is the output. The pin relationship of U2 is as follows: pin 1 GND is the ground pin, pin 2 TRI is the trigger pin, pin 3 OUT is the output pin, pin 4 RST is the reset pin, pin 5 CON is the control pin, pin 6 THR is the critical pin, pin 7 DIS is the discharge pin, and pin 8 VDD is the power supply pin.

[0021] c) Comparator U3 (LM139GJ) has an output terminal at the left end 2, an output terminal at the upper end 3 connected to the power supply VCC, a ground terminal at the lower end 12, and the positive input terminal 5 and the inverted input terminal 4 on the right end from top to bottom.

[0022] d) The SCR1 thyristor is selected as 3CT2324;

[0023] e) The field-effect transistor Q1 is selected as CS250.

[0024] This invention proposes an electronic self-excited fixed-frequency ignition circuit. It employs a timer module to control the switching frequency in the inverter circuit. This frequency is fixed and, combined with a feedback module, forms a PWM (Pulse Width Modulation) circuit. When the input voltage is low, the duty cycle of the timer module output is increased; when the input voltage is high, the duty cycle of the timer module output is decreased, ensuring a constant power transmission to the high-voltage circuit. The circuit proposed in this invention has been applied in a newly developed ignition device. This ignition device requires an input voltage of (18–32) VDC, an ignition frequency of (2.9–3.4) Hz, and a power not exceeding 80W. After performance testing, the ignition device achieved an ignition frequency of (3.2–3.3) Hz across the entire voltage range, a working current of 4A with an 18VDC input, and a working current of 2.3A with a 32VDC input, with a power not exceeding 72W. This meets the technical requirements and achieves the excellent function of maintaining the ignition frequency under low voltage input and ensuring that the power does not exceed the limit under high voltage input.

[0025] This invention has been applied to a newly developed ignition device. The voltage regulator module uses a CW78M12K regulator, and the timer module uses a JB555 timer. Appropriate resistors and capacitors are selected to set the timer output frequency to a square wave of 3000Hz and a duty cycle of 50%. The sampling control module uses an LM139GJ comparator and a 5kΩ potentiometer for sampling resistor R8. In the low-voltage circuit, the peak current is limited by adjusting the sampling resistance of R8. When the input is 18VDC, the duty cycle of the MOSFET is 46%, resulting in a longer conduction time; when the input is 32VDC, the duty cycle is 32%, resulting in a shorter conduction time. Therefore, within the specified input voltage range, a constant amount of electrical energy can be transferred from the low-voltage circuit to the high-voltage circuit, and the discharge frequency of the high-voltage circuit remains constant. Currently, this ignition device has passed functional performance tests and accelerated life tests, demonstrating good performance.

Claims

1. An electronic self-excited fixed-frequency ignition circuit, characterized in that, It includes a filter module, a voltage regulator module, a time base module, a sampling control module, a boost module, a rectifier energy storage module, and a discharge module connected in sequence. The filter module receives the power input, and the discharge module outputs a high-voltage pulse. The time base module includes: a time base circuit U2, resistors R1 to R4, and capacitors C5 to C7. One end of resistor R1 is connected to one end of resistor R2 and the power supply pin of time base circuit U2; the other end of resistor R1 is connected to one end of capacitor C5 and the reset pin of time base circuit U2; the other end of resistor R2 is connected to one end of resistor R3 and the discharge pin of time base circuit U2; the other end of capacitor C5 is connected to one end of capacitor C6, one end of capacitor C7, and the ground pin of time base circuit U2; the other end of resistor R3 is connected to the other end of capacitor C6, pin 6 of time base circuit U2, and the trigger pin of time base circuit U2; the other end of capacitor C7 is connected to the control pin of time base circuit U2; and one end of resistor R4 is connected to the output pin of time base circuit U2. The sampling control module includes comparator U3, thyristor SCR1, diode D6, resistors R5-R10, and capacitor C8. The positive input terminal of comparator U3 is connected to one end of resistor R7 and one end of capacitor C8; the negative input terminal of comparator U3 is connected to the adjustment terminal of adjustable resistor R8; the output terminal of comparator U3 is connected to one end of resistor R5 and the negative terminal of diode D6; the positive terminal of thyristor SCR1 is connected to the other end of resistor R4, one end of resistor R9, and the gate of field-effect transistor Q1; the negative terminal of thyristor SCR1 is connected to the positive terminal of diode D6, one end of resistor R8, the other end of resistor R9, one end of resistor R10, and the other end of capacitor C8; the other end of resistor R5 is connected to the power supply pin of timer circuit U2 and one end of resistor R6; the other end of resistor R6 is connected to the other end of resistor R8; and the other end of resistor R7 is connected to the other end of resistor R10.

2. The electronic self-excited fixed-frequency ignition circuit according to claim 1, characterized in that, The voltage regulator module includes a three-terminal voltage regulator U1, diodes D1 to D3, and capacitors C1 to C4. The input terminal of the three-terminal voltage regulator U1 is connected to one end of capacitor C1, the cathode of diode D2, one end of capacitor C2, the cathode of diode D1, and one output terminal of the filter. The output terminal of the three-terminal regulator U1 is connected to one end of capacitor C3, the positive terminal of diode D1, one end of capacitor C4, and the negative terminal of diode D3. The voltage regulator U1 is connected to the other end of capacitor C1, the other end of capacitor C2, the positive terminal of diode D2, the other end of capacitor C3, the positive terminal of diode D3, the other end of capacitor C4, and the other output terminal of the filter.

3. The electronic self-excited fixed-frequency ignition circuit according to claim 2, characterized in that, The boost module includes diodes D4 and D5 and transformer T1, wherein, The positive terminal of diode D4 is connected to the negative terminal of diode D5; The negative terminal of diode D4 is connected to one output terminal of the filter and one input terminal of transformer T1; The negative terminal of diode D5 is connected to the drain of field-effect transistor Q1 and the other input terminal of transformer T1.

4. The electronic self-excited fixed-frequency ignition circuit according to claim 3, characterized in that, The rectifier energy storage module includes a silicon stack D7 and a capacitor C9. The positive terminal of the silicon stack D7 is connected to one output terminal of the transformer T1. The two ends of the capacitor C9 are connected to the negative terminal of the silicon stack D7 and the other output terminal of the transformer T1, respectively.

5. The electronic self-excited fixed-frequency ignition circuit according to claim 4, characterized in that, The discharge module includes a discharge tube V1 and a resistor R11. One end of the discharge tube V1 is connected to the negative terminal of the silicon stack D7; the other end of the discharge tube V1 is connected to one end of the resistor R11; and the other end of the resistor R11 is connected to the other output terminal of the transformer T1.

6. The electronic self-excited fixed-frequency ignition circuit according to claim 5, characterized in that, The three-terminal voltage regulator U1 is a CW78M12K.

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