CN114837908B - Ignition circuit of semiconductor spark plug for micro electric thruster - Google Patents

Abstract

The present invention belongs to the technical field of micro-satellite electric propulsion, and specifically is an ignition circuit for a semiconductor spark plug of a micro electric thruster. The ignition circuit of the present invention adopts a capacitor direct output design without an output transformer, which can effectively improve the ignition energy efficiency. The experimental results of the embodiment show that under the same working conditions, the ignition energy efficiency of the ignition circuit of the present invention is several times higher than that of the transformer ignition circuit. The simplification of the output network reduces the size and weight of the ignition circuit. The use of a dual closed-loop control system and a PID controller improves the steady-state voltage accuracy and voltage response rate of the power supply, makes the output voltage more precise, and enhances the load adjustment capability; the output voltage rise rate control design can optimize the energy efficiency of the spark plug ignition circuit.

Description

Ignition circuit of semiconductor spark plug for micro electric thruster

Technical Field

The invention belongs to the technical field of micro-satellite electric propulsion, and in particular relates to an ignition circuit of a semiconductor spark plug of a micro electric propulsion device.

Background Art

Pulsed Plasma Thruster (PPT) has been successfully applied to satellite attitude and orbit control and microsatellite main propulsion system due to its simple structure, small size, light weight, low power, high specific impulse and low thrust, to perform space propulsion tasks with high control accuracy. Among them, semiconductor spark plug is used as the igniter of PPT discharge, which has the advantages of simple structure, strong controllability and low cost, and has become the preferred starting method of PPT. The ignition circuit of the spark plug is a key component of PPT, which directly determines the ignition stability and life of the spark plug, and thus affects the performance stability and life of PPT.

At present, the spark plug ignition of the PPT system mainly adopts pulse transformer output drive [Lu Wentao. Research on active control of spacecraft surface potential based on pulse plasma source [D]. Graduate School of the Chinese Academy of Sciences (Space Science and Application Research Center), 2010] and composite drive [Hu Zongsen. Research on the performance of 40J pulsed plasma thruster (PPT) [D]; Chinese invention patent CN 107725297 A] and other technical routes. Among them, pulse transformer output drive ignition uses the pulse transformer to achieve secondary boost of the output, release the capacitor energy to the spark plug, and make the spark plug breakdown to complete ignition; composite drive ignition uses the unidirectional conduction characteristics of the diode to add a freewheeling capacitor on the basis of the pulse transformer output drive ignition to increase the spark plug ignition energy. Although the above two ignition circuit designs can effectively ignite, they have some common defects:

1. Low energy conversion efficiency. Both designs above use two sets of transformers. The first set of transformers is used to convert the satellite-borne DC low voltage into DC high voltage to charge the capacitor, and the second set of transformers is used for secondary boosting to release the capacitor energy to the spark plug. Due to the leakage and magnetic saturation problems of transformers, the more transformers are used, the lower the energy conversion efficiency, and the volume and weight are difficult to be minimized, which is not conducive to satellite-borne applications.

2. The rising rate of the output voltage pulse is uncontrollable. The discharge of the spark plug includes two stages: heating and vaporization of the semiconductor film and breakdown and conduction of the vaporized group. The voltage rising rate affects the distribution of the spark plug injected energy between the vaporization and breakdown stages. Unreasonable distribution will reduce the energy efficiency of the spark plug. If the voltage rising rate is uncontrollable, it will restrict the further optimization of the spark plug energy efficiency.

3. Insufficient output steady-state accuracy and load adjustment capability. As the load of the driving power supply, the spark plug has a complex discharge, which requires the driving power supply to have a strong load adjustment capability and a stable output voltage. The existing design adopts a voltage negative feedback design to meet this requirement, that is, a single closed-loop voltage negative feedback, and the feedback amount is taken from the output voltage. However, the spark plug current changes faster than the voltage change, and the voltage negative feedback responds slowly to load changes, which is not as timely and rapid as the current feedback, resulting in insufficient steady-state accuracy and load adjustment capability of the power supply output. In addition, the voltage noise component of the circuit will cause changes in the system gain and phase. If there is no corresponding compensation network, it will cause circuit oscillation, so the anti-interference performance of the ignition circuit is not ideal.

Summary of the invention

The purpose of the present invention is to design a high-efficiency precision semiconductor spark plug ignition circuit with light weight, optimized ignition energy conversion efficiency and low load regulation rate in response to the design defects in the above three aspects.

The present invention adopts the following technical solution:

An ignition circuit for a semiconductor spark plug of a micro electric thruster comprises: a boost unit 1, a regulating control unit 2, an ignition output unit 3, an IGBT drive and control unit 4 and a low-voltage power supply unit 5; the boost unit 1 converts a satellite-borne DC low voltage VS into a DC high voltage to charge an energy storage capacitor in the ignition output unit 3; the regulating control unit 2 realizes accurate regulation and rapid stabilization of the charging voltage of the energy storage capacitor, and has overvoltage, overcurrent and short-circuit protection functions; the ignition output unit 3 makes the energy storage capacitor capacity of the semiconductor spark plug SP adjustable; the IGBT drive and control unit 4 controls the on and off of the IGBT in the ignition output unit 3 and the rising rate of the output voltage pulse according to an external trigger signal ET; the low-voltage power supply unit 5 supplies low-voltage power to the entire circuit.

The boost unit 1 includes an input filter and protection network 11, a push-pull inverter network 12 and a full-wave voltage doubler rectifier filter network 13. The input end of the input filter and protection network 11 is connected to the satellite-borne DC low voltage VS, and the output end is connected to the push-pull inverter network 12 to prevent damage to other units when the input end fails; the input end of the push-pull inverter network 12 is connected to the input filter and protection network 11 and the PWM control network 21, and the output end is connected to the full-wave voltage doubler rectifier filter network 13 and the current feedback network 22. Through the continuous alternating conduction and shutdown of the power tube, the satellite-borne DC low voltage VS is inverted into a square wave AC voltage, which is then boosted to a high-frequency AC square wave through a high-frequency transformer; the output end of the full-wave voltage doubler rectifier filter network 13 is connected to the energy storage capacitor adjustment network 31 to convert the high-frequency AC square wave into an adjustable DC high-voltage output.

The regulating control unit 2 includes a PWM control network 21, a current feedback network 22, a voltage feedback network 23 and an overcurrent protection network 24. The input end of the PWM control network 21 is connected to the current feedback network 22, the voltage feedback network 23, the overcurrent protection network 24 and the low-voltage power supply unit 5, and the output end is connected to the push-pull inverter network 12; the PWM control network 21 compares and modulates the feedback signals of the current feedback network 22 and the voltage feedback network 23 with the set voltage value, outputs a complementary and symmetrical PWM pulse signal, drives and controls the conduction and shutdown of the power tube in the push-pull inverter network 12, so that the boost unit 1 outputs a stable DC high voltage. The input end of the voltage feedback network 23 is connected to the energy storage capacitor regulating network 31, and the input end of the current feedback network 22 is connected to the push-pull inverter network 12. The current feedback network 22 and the voltage feedback network 23 constitute a double closed-loop control system, wherein the push-pull inverter network 12, the current feedback network 22 and the PWM control network 21 form a first closed loop, which serves as the inner loop of the double closed-loop control system, so that the system can quickly adjust the influence of load disturbance; the push-pull inverter network 12, the full-wave voltage doubler rectifier filter network 13, the voltage feedback network 23 and the PWM control network 21 form a second closed loop, which serves as the outer loop of the double closed-loop control system, so as to improve the stability of the output voltage. In addition, the current feedback network 22 and the voltage feedback network 23 both use PID controllers to adjust and compensate the voltage error, so as to improve the anti-interference performance of the circuit; the input end of the overcurrent protection network 24 is connected to the full-wave voltage doubler rectifier filter network 13, and when the detected current exceeds the set value, the pulse output of the PWM control network 21 is blocked, so that the circuit stops working, and the circuit plays an overcurrent protection role.

The ignition output unit 3 includes an energy storage capacitor adjustment network 31, an IGBT series network 32, an IGBT voltage balancing network 33 and a transient interference suppression network 34. The input end of the energy storage capacitor adjustment network 31 is connected to the full-wave voltage doubler rectifier filter network 13, and the output end is connected to the IGBT series network 32, so that the energy storage capacitor capacity is adjustable; the input end of the IGBT series network 32 is connected to the energy storage capacitor adjustment network 31, the IGBT voltage balancing network 33 and the voltage rise rate control network 43, and the output end is connected to the transient interference suppression network 34, and the spark plug ignition is controlled by receiving the external trigger signal ET in the IGBT drive and control unit 4; the IGBT series network 32 adopts a double-tube IGBT series connection to realize the single-tube IGBT function; the IGBT voltage balancing network 33 is used to solve the static and dynamic voltage balancing problems in the double-tube IGBT series connection; the output end of the transient interference suppression network 34 is connected to the spark plug, which is used to suppress the spark plug ignition reverse voltage and absorb overvoltage surges.

The IGBT drive and control unit 4 includes an optical fiber input network 41, an IGBT drive and protection network 42, and a voltage rise rate adjustment network 43. The input end of the optical fiber input network 41 is connected to the external trigger signal ET, and the output end is connected to the IGBT drive and protection network 42; the output end of the IGBT drive and protection network 42 is connected to the voltage rise rate control network 43 to drive and protect the IGBT in the IGBT series network 32; the output end of the voltage rise rate control network 43 is connected to the IGBT series network 32, and the output voltage pulse rise rate is controlled by changing the conduction rate of the IGBT in the IGBT series network 32, so as to optimize the spark plug ignition energy conversion efficiency.

The input end of the low-voltage power supply unit 5 is connected to the satellite-borne DC low voltage VS, and the output end is respectively connected to the PWM control network 21 and the IGBT drive and protection network 42 to provide low-voltage power to the spark plug ignition circuit.

Compared with the prior art, the present invention has the following beneficial effects:

The ignition circuit of the present invention adopts a capacitor direct output design without an output transformer, which can effectively improve the ignition energy efficiency. The experimental results of the embodiment show that under the same working conditions, the ignition energy efficiency of the ignition circuit of the present invention is several times higher than that of the transformer ignition circuit. The simplification of the output network reduces the volume and weight of the ignition circuit. The use of a dual closed-loop control system and a PID controller improves the steady-state voltage accuracy and voltage response rate of the power supply, makes the output voltage more precise, and enhances the load adjustment capability; the output voltage rise rate control design can optimize the energy efficiency of the spark plug ignition circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a block diagram of a high energy efficiency precision semiconductor spark plug ignition circuit of the present invention;

2 is a circuit diagram of an IGBT series network and a voltage rise rate control network according to an embodiment of the present invention;

FIG3 is a comparison of the energy efficiency of an embodiment of the present invention and the energy efficiency of a transformer ignition circuit;

FIG. 4 is an optimization characteristic of the ignition energy efficiency with the output voltage rising rate according to an embodiment of the present invention.

In the figure:

1 boost unit, 2 regulation control unit, 3 ignition output unit, 4 IGBT drive and control unit, 5 low voltage power supply unit;

11 filtering and protection network, 12 push-pull inverter network, 13 full-wave voltage doubler rectifier filtering network;

21PWM control network, 22 current feedback network, 23 voltage feedback network, 24 overcurrent protection network;

31 energy storage capacitor regulation network, 32 IGBT series network, 33 IGBT voltage balancing network, 34 transient interference suppression network;

41 optical fiber input network, 42 IGBT drive and protection network, 43 voltage rise rate control network;

VS onboard DC low voltage, SP semiconductor spark plug, ET external trigger signal.

DETAILED DESCRIPTION

The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

The structural block diagram of the embodiment of the specific scheme of the present invention is shown in Figure 1. The ignition circuit of a semiconductor spark plug of a micro electric thruster of the present invention is mainly composed of a boost unit 1, a regulating control unit 2, an ignition output unit 3, an IGBT drive and control unit 4 and a low-voltage power supply unit 5. The satellite-borne DC low voltage VS (usually 28V) is converted into a 2kV adjustable DC high voltage by the boost unit 1 to charge the energy storage capacitor in the ignition output unit 3; the external trigger signal ET controls and drives the on and off of the IGBT in the ignition output unit 3 through the IGBT drive control unit 4, releases the energy of the energy storage capacitor to the spark plug, and ignites the spark plug; wherein, the regulating control unit 2 compares and modulates the current feedback signal and the voltage feedback signal with the set voltage value, so that the boost unit 1 outputs a stable DC high voltage; the low-voltage power supply unit 5 supplies low-voltage power to the spark plug ignition circuit.

The working principle and functions of this embodiment are as follows:

The boost unit 1 includes an input filter and protection network 11, a push-pull inverter network 12, and a full-wave voltage doubler rectifier filter network 13. The input end of the input filter and protection network 11 is connected to the satellite-borne DC low voltage VS, and the output end is connected to the push-pull inverter network 12, so as to prevent damage to other units when the input end fails; the input end of the push-pull inverter network 12 is respectively connected to the input filter and protection network 11 and the PWM control network 21, and the output end is respectively connected to the full-wave voltage doubler rectifier filter network 13 and the current feedback network 22, and the output signal of the PWM control network 21 is used to control the continuous alternating conduction and shutdown of the power tube, and the satellite-borne DC low voltage VS is inverted into a square wave AC voltage, which is then increased to a high-frequency AC square wave with an amplitude of 500V by a high-frequency transformer, and then converted into a 2kV adjustable DC high voltage output by the full-wave voltage doubler rectifier filter network 13; the output end of the full-wave voltage doubler rectifier filter network 13 is connected to the energy storage capacitor adjustment network 31, and a stable DC high voltage is provided for the energy storage capacitor in the energy storage capacitor adjustment network 31. The present invention adopts full-wave voltage doubler rectification, which reduces the electrical stress and insulation protection difficulty of key rectifying components, improves the reliability of the circuit, and reduces the output voltage ripple compared to the symmetrical voltage doubler rectification in the Chinese invention patent CN 107769582B.

The above-mentioned regulating and controlling unit 2 includes a PWM control network 21, a current feedback network 22, a voltage feedback network 23 and an overcurrent protection network 24. The input end of the PWM control network 21 is respectively connected to the current feedback network 22, the voltage feedback network 23, the overcurrent protection network 24 and the low-voltage power supply unit 5, and the output end is connected to the push-pull inverter network 12, and the feedback signals of the current feedback network 22 and the voltage feedback network 23 are compared and modulated with the set voltage value, and a complementary and symmetrical PWM pulse signal is output, and the conduction and shutdown of the power tube in the push-pull inverter network 12 are adjusted by adjusting the duty cycle of the power tube drive signal, so that the boost unit 1 outputs a stable DC high voltage; the input end of the current feedback network 22 The push-pull inverter network 12 is connected, the input end of the voltage feedback network 23 is connected to the energy storage capacitor adjustment network 31, and the current feedback network 22 and the voltage feedback network 23 form a double closed-loop control system, wherein the push-pull inverter network 12, the current feedback network 22 and the PWM control network 21 form a first closed loop as the inner loop of the double closed-loop control system; the push-pull inverter network 12, the full-wave voltage doubler rectifier network 13, the voltage feedback network 23 and the PWM control network 21 form a second closed loop as the outer loop of the double closed-loop control system. The working principle is: the sampling resistor samples the voltage, compares it with the set voltage to obtain the voltage error, and the voltage feedback outer loop PID controller adjusts and compensates the voltage error as the reference signal of the current feedback inner loop, compares the reference signal with the current detected by the current feedback inner loop, and obtains the output current error, and then the current feedback inner loop PID controller adjusts and compensates the current error, and then outputs the corresponding PWM pulse signal. Because the change of spark plug ignition current is faster than that of voltage, the current feedback inner loop enables the system to quickly adjust the influence of load disturbance, and the voltage feedback outer loop improves the stability of the output voltage. The present invention adopts a double closed-loop feedback design to enable the system to quickly adjust the influence of load disturbance, improve the stability of the output voltage, and at the same time, the PID controller can effectively compensate for the gain and phase changes caused by the voltage noise component in the circuit, improve the anti-interference of the circuit, and make the output of the semiconductor spark plug ignition circuit more precise. Compared with the single closed-loop voltage feedback in Chinese invention patents CN101943148A and CN107725297A, the double closed-loop feedback design can overcome the problem of insufficient adjustment ability of single-loop feedback to load disturbance. The input end of the overcurrent protection network 24 is connected to the full-wave voltage doubler rectifier filter network 13. When the detected current exceeds the set value, the pulse output of the PWM control network 21 is blocked, the circuit stops working, and the circuit is protected from overcurrent.

The above-mentioned ignition output unit 3 includes an energy storage capacitor adjustment network 31, an IGBT series network 32, an IGBT voltage balancing network 33, and a transient interference suppression network 34. Among them, the input end of the energy storage capacitor adjustment network 31 is connected to the full-wave voltage doubler rectifier filter network 13, and the output end is connected to the IGBT series network 32, which is used to realize the adjustable capacity of the energy storage capacitor; the input end of the IGBT series network 32 is respectively connected to the energy storage capacitor adjustment network 31, the IGBT voltage balancing network 33 and the voltage rise rate control network 43, and the output end is connected to the transient interference suppression network 34, and the spark plug ignition is controlled by the external trigger signal ET in the receiving unit 4. In order to reduce the volume of the ignition circuit, the IGBT series network 32 uses a double-tube IGBT in series to realize the function of a single-tube IGBT. This embodiment is based on the nominal performance of the spark plug used in the experiment: rated voltage 1200V, peak current 200A, the ignition circuit output voltage is designed to be 2000V adjustable, fluctuation 5%, insurance factor 10%, the required withstand voltage value is 2400V, the current capacity is 300A, and the double-tube IGBT of 300A/2400V is about half the size of the single-tube IGBT. The static and dynamic voltage equalization problems of the series IGBT are solved by the IGBT voltage equalization network 33; the output end of the transient interference suppression network 34 is connected to the spark plug to suppress the spark plug ignition reverse voltage and absorb overvoltage surges. The unit has no output pulse transformer, but a capacitor direct discharge design, which reduces about 40% of the energy loss caused by problems such as transformer magnetic saturation leakage, improves the circuit energy conversion efficiency, and can reduce about 25% of the volume and 35% of the weight. The present invention replaces the transformer boosting scheme with a push-pull inverter combined with a voltage doubling rectifier scheme, and adopts a capacitor direct discharge design to release the capacitor energy directly to the spark plug. Compared with the ignition circuit of "Lu Wentao: Research on Active Control of Spacecraft Surface Potential Based on Pulsed Plasma Source" and the ignition circuit of Chinese invention patent CN 107725297A, the secondary boosting transformer is cancelled, which can reduce the energy consumption caused by the magnetic saturation and leakage of the transformer, significantly improve the energy conversion efficiency of the circuit, and reduce the size and weight of the power supply at the same time, which is beneficial to spaceborne applications.

The above-mentioned IGBT drive control unit 4 includes an optical fiber input network 41, an IGBT drive and protection network 42, and a voltage rise rate control network 43. Among them, the input end of the optical fiber input network 41 is connected to the external trigger signal ET, and the output end is connected to the IGBT drive and protection network 42, so as to realize the isolation and transmission of the external trigger signal; the output end of the IGBT drive and protection network 42 is connected to the voltage rise rate control network 43, so as to drive and protect the IGBT in the IGBT series network 32; the output end of the voltage rise rate control network 43 is connected to the IGBT series network 32, and the output voltage pulse rise rate is controlled by changing the conduction rate of the IGBT in the IGBT series network 32, so as to realize the optimization of the spark plug ignition energy conversion efficiency.

In one specific embodiment, the circuit diagram of the IGBT series network 32 and the voltage rise rate control network 43 is shown in FIG2 . The first IGBT1 and the second IGBT2 are connected in series to form the IGBT series network 32. The voltage rise rate control network 43 includes the first to second drive interfaces (J1, J2), the first to fourth resistors (R1, R2, R4, R5), the first to sixth diodes (D1, D2, D3, D4, D5, D6), the first to second variable gate resistors (VR1, VR2), the first to second gate emitter capacitors (CG1, CG2), the first to second gate discharge resistors (R3, R6), and the first to second bidirectional transient voltage suppressor diodes (TVS1, TVS2).

Among them, the C interface of the first drive interface J1 is connected in series with the first resistor R1, the first diode D1, and the second diode D2 in sequence, and then connected to the collector end of the first IGBT1, and the directions of the first diode D1 and the second diode D2 both point to the collector end of the first IGBT1; the G interface of the first drive interface J1 is connected in series with the first variable gate resistor VR1 and the second resistor R2 in sequence, and then connected to the gate end of the first IGBT1, and the third diode D3 is connected in parallel at both ends of the second resistor R2, and the direction points to the gate end of the first IGBT1; the E interface of the first drive interface J1 is connected to the emitter end of the first IGBT1, and the first bidirectional transient voltage suppression diode TVS1, the first gate discharge resistor R3, and the first gate-emitter capacitor CG1 are connected in parallel in sequence between the gate and emitter of the first IGBT1. The C interface of the second drive interface J2 is connected in series with the third resistor R4, the fourth diode D4, and the fifth diode D5 in sequence, and then connected to the collector end of the second IGBT2. The directions of the fourth diode D4 and the fifth diode D5 both point to the collector end of the second IGBT2; the G interface of the second drive interface J2 is connected in series with the second variable gate resistor VR2 and the fourth resistor R5 in sequence, and then connected to the gate end of the second IGBT2. The sixth diode D6 is connected in parallel at both ends of the fourth resistor R5, and its direction points to the gate end of the second IGBT2; the E interface of the second drive interface J2 is connected to the emitter end of the second IGBT2, and the second bidirectional transient voltage suppression diode TVS2, the second gate discharge resistor R6, and the second gate-emitter capacitor CG2 are connected in parallel in sequence between the gate and emitter of the second IGBT2. Among them, the first resistor R1 and the fourth resistor R4 are respectively used to reduce the reverse peak current on the first diode D1, the second diode D2, the fourth diode D4, and the fifth diode D5, while the first diode D1, the second diode (D2), the fourth diode D4, and the fifth diode D5 are respectively used to suppress the high-voltage spike pulses on the collectors of the first IGBT1 and the second IGBT2; the first and second bidirectional transient voltage suppression diodes TVS1 and TVS2 are respectively used to suppress the forward and reverse peak voltages of the first IGBT1 and the second IGBT2 to prevent IGBT voltage overshoot; the first variable gate resistor VR2, the first gate-emitter capacitor CG1 and the second variable gate resistor VR2 and the second gate-emitter capacitor CG2 are respectively used to adjust the conduction rate of the first IGBT1 and the second IGBT2; the first and second gate discharge resistors (R3, R6) are respectively used to prevent the gates of the first IGBT1 and the second IGBT2 from being broken down by static electricity; the first drive interface J1 and the second drive interface J2 are connected to the IGBT drive chip in the IGBT drive protection network 42.

In the IGBT voltage rise rate control network 43, when the first IGBT1 is turned on, the driving current flows to the gate of IGBT1 through the first variable gate resistor VR1 and the third diode D3, that is, the gate resistor Rg=VR1. When the first IGBT1 is turned off, due to the unidirectional conductivity of the third diode D3, the IGBT gate is discharged through the first variable gate resistor VR1 and the second resistor R2, that is, the gate resistor Rg=VR1+R2. In this way, the voltage change rate dv/dt of the IGBT1 turning on and off can be controlled respectively, and the spike pulse value of the IGBT collector voltage can be reduced, thereby improving the switching process and reducing the switching loss.

By adjusting the variable gate resistor (VR1, VR2) of 0-20Ω and the variable gate-emitter capacitor (CG1, CG2) of 0-30nF, the conduction rate of the IGBT is changed, so that the rise rate of the output voltage pulse of the spark plug ignition circuit can be controlled at 3000-8000V/μs. The optimization principle of controlling the rise rate of the output voltage pulse for energy conversion efficiency is: the ignition process of the spark plug includes two stages: heating and vaporization of the semiconductor film and breakdown and conduction of the vaporized group. The voltage pulse applied to the spark plug drives the completion of the two stages. The voltage rise rate determines the heating and vaporization time of the semiconductor film. If the rise rate is too fast, although the semiconductor film temperature rise rate is fast, due to the short duration, the density of the vaporized group formed is too low, resulting in difficulty in breakdown and insufficient charged particles; if the voltage rise rate is too slow, the heating stage will be extended, and excessive heating energy consumption and heat dissipation loss will reduce the energy of the breakdown stage, which will also lead to insufficient charged particles. Optimizing the voltage rise rate can not only improve the energy conversion efficiency of the ignition circuit, but also improve the ignition quality of the spark plug. In the safe working area of IGBT, selecting appropriate gate resistance and gate-emitter capacitance can reduce the IGBT Miller effect and optimize the spark plug ignition energy conversion efficiency.

The input end of the low-voltage power supply unit 5 is connected to the satellite power supply, and the output end is connected to the PWM control network 21 and the IGBT drive protection network 42 respectively, converting the satellite DC low voltage VS 28V into DC 15V and ±5V to provide low-voltage power for the spark plug ignition circuit.

experiment

Experiment 1, in order to test the energy efficiency of the semiconductor spark plug ignition circuit of the present invention, two application examples were made according to the transformer output drive ignition circuit and the present invention. Under the conditions of energy storage capacitor 0.1μF and lower vacuum degree, the same semiconductor spark plug was used to conduct a comparative test on the two ignition circuits, and the obtained ignition energy versus voltage curve is shown in Figure 3.

As shown in Figure 3, under the same working conditions, the ignition circuit of the present invention can increase the spark plug ignition energy by 1.6 to 2.6 times compared with the transformer output drive ignition circuit. The ignition circuit of the present invention greatly improves the energy conversion efficiency of the spark plug.

Experiment 2, in order to test the controllability of the ignition circuit of the present invention on the output voltage pulse rise rate, the ignition energy efficiency was tested as a function of the output voltage rise rate under the conditions of a 0.1 μF energy storage capacitor and a relatively low vacuum degree.

The output voltage rise rate is controlled by changing the variable gate resistance value in the voltage rise rate control network 43. Under the premise of ensuring effective ignition of the spark plug, the gate-emitter capacitance is controlled unchanged, and the variable gate resistance is adjusted. The optimized characteristic curve of energy efficiency versus output voltage pulse rise rate is shown in FIG4 .

As shown in Figure 4, under the same energy storage capacity and different charging voltage conditions, the semiconductor spark plug achieves the highest ignition energy when the gate resistance Rg = 2Ω. It can be seen that the voltage rise rate control network can optimize the energy distribution of the spark plug and improve the energy conversion efficiency of the ignition circuit.

Claims (1)

1. An ignition circuit for a semiconductor spark plug of a micro electric thruster, characterized in that the ignition circuit for the semiconductor spark plug of the micro electric thruster comprises: a boost unit (1), a regulating control unit (2), an ignition output unit (3), an IGBT drive and control unit (4) and a low-voltage power supply unit (5); the boost unit (1) converts a satellite-borne DC low voltage (VS) into a DC high voltage to charge an energy storage capacitor in the ignition output unit (3); the regulating control unit (2) realizes regulating and stabilizing the charging voltage of the energy storage capacitor and has overvoltage, overcurrent and short-circuit protection functions; the ignition output unit (3) makes the energy storage capacitor capacity of the semiconductor spark plug (SP) adjustable; the IGBT drive and control unit (4) controls the on and off of the IGBT in the ignition output unit (3) and the rising rate of the output voltage pulse according to an external trigger signal (ET); the low-voltage power supply unit (5) supplies low-voltage power to the entire circuit; The boost unit (1) comprises an input filter and protection network (11), a push-pull inverter network (12) and a full-wave voltage-doubling rectifier filter network (13); wherein the input end of the input filter and protection network (11) is connected to a satellite-borne DC low voltage (VS), and the output end is connected to the push-pull inverter network (12) to prevent damage to other units when an input end fails; the input end of the push-pull inverter network (12) is connected to the input filter and protection network (11) and the PWM control network (21), and the output end is connected to the full-wave voltage-doubling rectifier filter network (13) and the current feedback network (22); the satellite-borne DC low voltage (VS) is inverted into a square wave AC voltage by continuously alternating on and off the power tube, and then boosted into a high-frequency AC square wave through a high-frequency transformer; the output end of the full-wave voltage-doubling rectifier filter network (13) is connected to an energy storage capacitor adjustment network (31) to convert the high-frequency AC square wave into an adjustable DC high-voltage output; The regulating control unit (2) comprises a PWM control network (21), a current feedback network (22), a voltage feedback network (23) and an overcurrent protection network (24); wherein the input end of the PWM control network (21) is connected to the current feedback network (22), the voltage feedback network (23), the overcurrent protection network (24) and the low-voltage power supply unit (5), and the output end is connected to the push-pull inverter network (12); the PWM control network (21) compares and modulates the feedback signals of the current feedback network (22) and the voltage feedback network (23) with the set voltage value, outputs a complementary and symmetrical PWM pulse signal, drives and controls the conduction and shutdown of the power tube in the push-pull inverter network (12), and enables the boost unit (1) to output a stable DC high voltage; the input end of the voltage feedback network (23) is connected to the energy storage capacitor regulating network (31), and the input end of the current feedback network (22) is connected to the push-pull inverter network (12); the current feedback network (22) is connected to the The voltage feedback network (23) constitutes a double closed-loop control system, wherein the push-pull inverter network (12), the current feedback network (22) and the PWM control network (21) form a first closed loop as the inner loop of the double closed-loop control system, so that the system can quickly adjust the influence of load disturbance; the push-pull inverter network (12), the full-wave voltage doubler rectifier filter network (13), the voltage feedback network (23) and the PWM control network (21) form a second closed loop as the outer loop of the double closed-loop control system, so as to improve the stability of the output voltage; and the current feedback network (22) and the voltage feedback network (23) both use a PID controller to adjust and compensate for the voltage error, so as to improve the anti-interference performance of the circuit; the input end of the overcurrent protection network (24) is connected to the full-wave voltage doubler rectifier filter network (13), and when the detected current exceeds the set value, the pulse output of the PWM control network (21) is blocked, so that the circuit stops working, thereby playing an overcurrent protection role for the circuit; The ignition output unit (3) comprises an energy storage capacitor adjustment network (31), an IGBT series network (32), an IGBT voltage balancing network (33) and a transient interference suppression network (34); wherein the input end of the energy storage capacitor adjustment network (31) is connected to a full-wave voltage doubler rectifier filter network (13), and the output end is connected to the IGBT series network (32), so that the energy storage capacitor capacity is adjustable; the input end of the IGBT series network (32) is connected to the energy storage capacitor adjustment network (31), the IGBT voltage balancing network (33) and the voltage rise rate adjustment network (34). The voltage-equalizing network (33) is connected to a voltage-equalizing network (43), and the output end is connected to a transient interference suppression network (34), and controls the spark plug ignition by receiving an external trigger signal (ET) in an IGBT drive and control unit 4; the IGBT series network (32) uses a double-tube IGBT in series to realize the function of a single-tube IGBT; the IGBT voltage-equalizing network (33) is used to solve the static and dynamic voltage-equalizing problems in the double-tube IGBT in series; the output end of the transient interference suppression network (34) is connected to a spark plug, and is used to suppress the reverse voltage of the spark plug ignition and absorb overvoltage surges; The IGBT drive and control unit (4) comprises an optical fiber input network (41), an IGBT drive and protection network (42) and a voltage rise rate control network (43); wherein the input end of the optical fiber input network (41) is connected to an external trigger signal (ET), and the output end is connected to the IGBT drive and protection network (42); the output end of the IGBT drive and protection network (42) is connected to the voltage rise rate control network (43) to drive and protect the IGBT in the IGBT series network (32); the output end of the voltage rise rate control network (43) is connected to the IGBT series network (32) to control the output voltage pulse rise rate by changing the conduction rate of the IGBT in the IGBT series network (32), thereby optimizing the spark plug ignition energy conversion efficiency; The input end of the low-voltage power supply unit (5) is connected to the satellite-borne DC low voltage (VS), and the output end is respectively connected to the PWM control network (21) and the IGBT drive and protection network (42) to provide low-voltage power supply for the spark plug ignition circuit.