CN216161005U - A control circuit of a digital pulse igniter - Google Patents
A control circuit of a digital pulse igniter Download PDFInfo
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- CN216161005U CN216161005U CN202122287330.1U CN202122287330U CN216161005U CN 216161005 U CN216161005 U CN 216161005U CN 202122287330 U CN202122287330 U CN 202122287330U CN 216161005 U CN216161005 U CN 216161005U
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Abstract
本实用新型公开了一种数字式脉冲点火器的控制电路，属于点火器技术领域，点火模块包括储能电容和高压包；驱动控制模块的反馈输入端与点火模块电连接，驱动控制模块用于根据储能电容的实际电压实时调整PWM信号的占空比；驱动控制模块的PWM信号输出端与升压模块的控制端电连接，升压模块与储能电容电连接，驱动控制模块还用于通过PWM信号控制升压模块为储能电容充电；驱动控制模块的TRI信号输出端与触发放电模块的控制端电连接，触发放电模块与储能电容电连接，驱动控制模块还用于通过TRI信号控制触发放电模块将储能电容放电。本实用新型解决了现有脉冲点火器点火功率低，不精确，且不能随意调节储能电容的充电目标电压的问题。
The utility model discloses a control circuit of a digital pulse igniter, which belongs to the technical field of igniters. According to the actual voltage of the energy storage capacitor, the duty cycle of the PWM signal is adjusted in real time; the PWM signal output end of the drive control module is electrically connected to the control end of the booster module, the booster module is electrically connected to the energy storage capacitor, and the drive control module is also used for The boost module is controlled by the PWM signal to charge the energy storage capacitor; the TRI signal output end of the drive control module is electrically connected to the control end of the trigger discharge module, the trigger discharge module is electrically connected to the energy storage capacitor, and the drive control module is also used to pass the TRI signal Control the trigger discharge module to discharge the energy storage capacitor. The utility model solves the problems of low ignition power and inaccuracy of the existing pulse igniter, and the charging target voltage of the energy storage capacitor cannot be adjusted at will.
Description
Technical Field
The utility model relates to the technical field of igniters, in particular to a control circuit of a digital pulse igniter.
Background
At present, igniters adopted by household gas cookers and gas water heaters are basically electronic, and are based on a pulse principle and adopt an analog control circuit. The analog control circuit is generally composed of a self-oscillation module, a trigger module and an ignition module. Taking a common igniter circuit of a gas water heater as an example, as shown in fig. 1, the self-oscillation module comprises a diode D, a triode Q1, a Q2, a resistor R, and a transformer T1, a core element of the trigger module is a trigger tube or thyristor, and the ignition module comprises an energy storage capacitor C and a high voltage pack T2. When the triode Q2 is turned on, the self-oscillation module is powered on to work, the secondary winding of the transformer T1 outputs an oscillation waveform, and the energy storage capacitor C is charged through the diode D in the positive half-wave stage of the oscillation waveform. As shown in fig. 1, the direction of arrow 100 is the current direction when the self-oscillation module charges the energy storage capacitor C. When the energy storage capacitor C is charged to a certain voltage value to meet the trigger condition of the trigger module, the trigger module is conducted, and the energy storage capacitor C discharges instantly. As shown in fig. 1, the direction of arrow 200 is the direction of current flow when the energy storage capacitor C discharges into the primary winding of the high voltage package T2. While discharging, the secondary winding of the high voltage package T2 induces an oscillating waveform of high voltage, which in turn breaks down the air and forms an arc.
The household pulse igniter is generally powered by direct current, the input voltage range is 2.1-5V, the trigger voltage range is 150-200V, and the formula is P ═ C ═ U × f/2, where C is the capacitance of the energy storage capacitor, U is the charging target voltage (i.e. trigger voltage) of the energy storage capacitor, f is the discharge frequency, and the ignition power of the household pulse igniter is generally lower than 0.3W. In addition, the household pulse igniter adopts an analog control circuit, the parameters of electronic elements of the household pulse igniter are fixed, the ignition power of the igniter cannot be changed at will, if the ignition power needs to be increased, the igniter is pulled to move the whole body, and the design is equivalent to redesign. In addition, since there is an error in the trigger voltage of the trigger module of the igniter, this may affect the precision of the ignition power thereof, and ultimately the performance of the igniter (including output high voltage, discharge frequency, discharge energy, etc.). During mass production, if manufacturers check the performance parameters of each igniter, a large amount of working hours are involved, so that the cost is increased and the production efficiency is reduced; if the manufacturer does not check the performance parameters of each igniter, the use experience of part of users may be affected, such as difficult ignition.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned drawbacks, the present invention provides a control circuit for a digital pulse igniter, which solves the problems of low ignition power, inaccuracy and incapability of randomly adjusting the charging target voltage of an energy storage capacitor of the conventional pulse igniter.
In order to achieve the purpose, the utility model adopts the following technical scheme: a control circuit of a digital pulse igniter comprises a driving control module, a boosting module, an ignition module, a voltage acquisition module and a trigger discharge module;
the ignition module comprises an energy storage capacitor and a high-voltage pack, the energy storage capacitor is electrically connected with a primary coil of the high-voltage pack, and a secondary coil of the high-voltage pack is electrically connected with an ignition needle;
the feedback input end of the driving control module is electrically connected with the ignition module through the voltage acquisition module, and the driving control module is used for adjusting the duty ratio of a PWM signal in real time according to the actual voltage of the energy storage capacitor;
the PWM signal output end of the drive control module is electrically connected with the control end of the boosting module, the boosting module is electrically connected with the energy storage capacitor, and the drive control module is also used for controlling the boosting module to charge the energy storage capacitor through the PWM signal;
the TRI signal output end of the driving control module is electrically connected with the control end of the trigger discharging module, the trigger discharging module is electrically connected with the energy storage capacitor, and the driving module is further used for controlling the trigger discharging module to discharge the energy storage capacitor through the TRI signal.
It is worth to say that, the boost module includes a power inductor, and the power inductor is electrically connected with the energy storage capacitor through a rectifier diode;
the boost module is used for enabling the power inductor to store energy when the PWM signal output by the drive control module is at a high level; the boost module is further used for enabling the power inductor to release energy when the PWM signal output by the drive control module is at a low level, so that the energy storage capacitor is charged.
Specifically, the driving control module is used for controlling the boosting module to work in a discontinuous conduction mode through the PWM signal.
Preferably, the power supply further comprises a voltage acquisition module, an input end of the voltage acquisition module is electrically connected with the energy storage capacitor, and an output end of the voltage acquisition module is electrically connected with a VOL signal input end of the driving control module;
the voltage acquisition module is used for acquiring the voltage of the energy storage capacitor and transmitting the voltage to the drive control module through the VOL signal input end;
the driving control module is also used for carrying out analog-to-digital conversion on the voltage of the energy storage capacitor in real time.
It is worth to say, still include power module, power module's input is connected with the power electricity, power module's output with the power inductance electricity is connected, power module is used for to boost the module power supply.
Optionally, the control terminal of the power supply module is electrically connected with the PWR signal output terminal of the drive control module;
the drive control module is further used for controlling the power supply module to stop supplying power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor exceeds a preset charging target voltage; and the power supply module is also used for controlling the power supply module to supply power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor does not exceed a preset charging target voltage.
The power supply module is characterized by further comprising an overcurrent detection module, wherein the input end of the overcurrent detection module is electrically connected with a power supply, the output end of the overcurrent detection module is electrically connected with the input end of the power supply module, and the control end of the overcurrent detection module is electrically connected with the TST signal input end of the drive control module;
the overcurrent detection module is used for inputting a TST effective level to a TST signal input end of the drive control module when the power supply circuit is in overcurrent;
the drive control module is used for controlling the power supply module to stop supplying power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor is lower than a preset lower limit threshold and/or the TST effective level is received.
Preferably, the overcurrent protection device further comprises an automatic power-off module, wherein the input end of the automatic power-off module is electrically connected with the control end of the overcurrent detection module, and the output end of the automatic power-off module is electrically connected with the control end of the power supply module;
the automatic power-off module is used for outputting a power-off signal to the control end of the power supply module when receiving the TST effective level;
the power supply module is used for stopping supplying power to the boosting module after receiving the power-off signal.
It is worth to say, still include step-down voltage regulator module, the input of step-down voltage regulator module is connected with the power electricity, the output of step-down voltage regulator module is connected with the power supply input electricity of drive control module, step-down voltage regulator module is used for supplying power for drive control module after stepping down to the voltage of power.
Optionally, the driving control module is a microcontroller MCU, the driving control module uses a system clock with a frequency of 8MHz, and the PWM signal is an 8-bit PWM signal.
One of the above technical solutions has the following beneficial effects:
1. in the control circuit of digital pulse igniter, through drive control module boost module ignition module with trigger the module of discharging and constitute digital circuit, through control drive control module control boost module with trigger the module of discharging, can realize right the quick charge of the energy storage electric capacity of ignition module, and can adjust at will energy storage electric capacity's the target voltage that charges and charge-discharge cycle, only need be in change the parameter in drive control module's the procedure of presetting, just can change ignition power to the control circuit that enables digital pulse igniter can be applicable to various equipment and the device that need the function of igniting, adaptability is wide.
2. In the control circuit of the digital pulse igniter, the drive control module can realize high-precision control of the charging target voltage, and can also realize high-precision control of the charging and discharging period, so that high-precision ignition power control is realized. During batch production, parameters of the electronic elements do not need to be modified according to factory inspection standards, and production efficiency is greatly improved.
Drawings
FIG. 1 is a prior art analog pulse igniter circuit;
FIG. 2 is a control circuit for a digital pulse igniter according to an embodiment of the utility model;
fig. 3 is a timing diagram of control signals for the control circuit of the digital pulse igniter according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.
The following disclosure provides many different embodiments or examples for implementing different configurations of embodiments of the utility model. In order to simplify the disclosure of embodiments of the utility model, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, embodiments of the utility model may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed.
As shown in fig. 2 and 3, a control circuit of a digital pulse igniter includes a driving control module, a voltage boosting module, an ignition module, a voltage collecting module and a trigger discharging module; the ignition module comprises an energy storage capacitor and a high-voltage pack, the energy storage capacitor is electrically connected with a primary coil of the high-voltage pack, and a secondary coil of the high-voltage pack is electrically connected with an ignition needle; specifically, the high-voltage package is a step-up transformer for generating a high voltage of 12kV or more, and the energy storage capacitor is preferably a CBB energy storage capacitor. The feedback input end of the driving control module is electrically connected with the ignition module through the voltage acquisition module, and the driving control module is used for adjusting the duty ratio of a PWM signal in real time according to the actual voltage of the energy storage capacitor; specifically, the frequency of the PWM signal is fixed, i.e., the period is fixed. According to the volt-second formula V1 × T1 — V2 × T2, where V1 is the voltage difference across the inductor during energy storage of the power inductor, the value of which is equal to the input voltage under an ideal circuit model, T1 is the duration of the high level of the PWM signal, the ratio of T1 to the PWM period is the duty cycle of the PWM signal, V2 is the voltage difference across the inductor during energy release of the energy storage capacitor, the value of which is equal to the difference between the voltage value of the energy storage capacitor and the input voltage under the ideal circuit model, and T2 is the duration of the energy release of the energy storage capacitor, since the input voltage is fixed, i.e., V1 is constant, V2 increases as the voltage of the energy storage capacitor increases, and if the duty cycle of the PWM signal is kept constant, i.e., T1 is constant, T2 decreases. In order to increase the charging current to accelerate the charging speed, the whole PWM signal period is fully utilized, T2 is increased by increasing T1, so that the sum of T1 and T2 always tends to be equal to the period value of the PWM signal, and therefore the duty ratio of the PWM signal is increased along with the increase of the energy storage capacitor voltage V2. The PWM signal output end of the drive control module is electrically connected with the control end of the boosting module, the boosting module is electrically connected with the energy storage capacitor, and the drive control module is also used for controlling the boosting module to charge the energy storage capacitor through the PWM signal; the TRI signal output end of the driving control module is electrically connected with the control end of the trigger discharging module, the trigger discharging module is electrically connected with the energy storage capacitor, and the driving module is further used for controlling the trigger discharging module to discharge the energy storage capacitor through the TRI signal. Specifically, the Boost module is a Boost type Boost circuit.
In the control circuit of digital pulse igniter, through drive control module boost module ignition module with trigger the module of discharging and constitute digital circuit, through control drive control module control boost module with trigger the module of discharging, can realize right the quick charge of the energy storage electric capacity of ignition module to can adjust at will energy storage electric capacity's the target voltage and the charge-discharge cycle of charging to the control circuit that enables digital pulse igniter can be applicable to various equipment and the device that need the function of igniteing, and adaptability is wide. In addition, the drive control module can realize the control of the charging target voltage with high precision through an analog-to-digital converter in the drive control module, and can realize the control of the charging and discharging period with high precision through a timer in the drive control module, thereby realizing the control of the ignition power with high precision. During batch production, parameters of the electronic elements do not need to be modified according to factory inspection standards, and production efficiency is greatly improved.
Compared with the simulation scheme of the traditional household pulse igniter, the embodiment of the utility model can randomly adjust the charging target voltage (namely the trigger voltage value) of the energy storage capacitor by adjusting the driving control module, thereby changing the ignition power and having wider adaptability. In addition, the precision of the charging target voltage can reach 1% level, so that the precision of the ignition power reaches 5% level, and compared with the traditional igniter using an analog circuit, the precision of the ignition power is higher. For example, in the embodiment of the present invention, a driving control module with a 10-bit or 12-bit analog-to-digital converter ADC is selected, and only it needs to ensure that the upper 7 bits of the analog-to-digital conversion result are accurate, assuming that the voltage division ratio of the voltage acquisition module is 45, and the driving control module is powered by 5V, the input voltage range of the port where the driving control module performs analog-to-digital conversion is up to 5V, and the error is less than 1LSB, where 1LSB (least significant bit) represents 45 × 5/(2^7) ═ 1.76V, and for a trigger discharge voltage of 200V, 1.76V corresponds to 0.88%, so the control accuracy of the driving control module on the charging target voltage can reach a level of 1%. When a 12-bit analog-to-digital conversion ADC is actually used, the accurate bit number is larger than 7 bits, and the precision can be higher. The igniter using the analog circuit even selects the imported trigger tube as the core element of the trigger module, and the error of the trigger voltage is +/-5 percent, which is much larger than the error of the utility model. In addition, in the embodiment of the utility model, the control of the drive control module on the charge-discharge period mainly depends on the precision of a system clock, and if an external crystal oscillator scheme is adopted, the error can be regarded as 0; if an internal oscillator scheme is used, the normal temperature can reach +/-2%. The igniter using the analog circuit has the discharge frequency related to input power, namely the resistance value of R, the amplification factor of Q1, the conduction voltage drop of Q1, the turn ratio of a primary winding and a feedback winding of T1 in figure 1, the conversion efficiency of the self-oscillation module and the trigger voltage of the trigger module, has very large error and can achieve the extraction of +/-10 percent. Assuming that the error of the capacitance of the energy storage capacitor is ± 1%, the calculation formula P ═ C × U × f/2 for the ignition power, and in the worst case, 1.01 × 1.02 ═ 1.051, i.e., the error of the present invention can be controlled within ± 5.1%, whereas the error of the igniter using the analog circuit, 1.01 × 1.05 × 1.10 ═ 1.225, can be controlled within ± 22.5%.
It is worth to say that, the boost module includes a power inductor, and the power inductor is electrically connected with the energy storage capacitor through a rectifier diode; the boost module is used for enabling the power inductor to store energy when the PWM signal output by the drive control module is at a high level; the boost module is further used for enabling the power inductor to release energy when the PWM signal output by the drive control module is at a low level, so that the energy storage capacitor is charged.
In one embodiment, the duty cycle of the PWM signal remains constant and is large enough for the boost module to operate in a continuous conduction mode. It should be noted that the continuous Conduction Mode is a CCM Mode, i.e., a continuous Conduction Mode. During the energy release of the power inductor, the PWM signal enters the next PWM cycle immediately before the current through the rectifier diode drops to 0. According to the volt-second formula V1 × T1 — V2 × T2, when V1 and T1 are fixed, T2 decreases with the increase of V2, T2 cannot be too small to ensure the charging speed in the later charging period, so the duty cycle of T1, i.e. the PWM signal, cannot be too small, but V2 in the earlier charging period approaches 0, so T2 is large, so that the sum of T1 and T2 is larger than the PWM period, in other words, the energy storage inductor enters the energy storage period again before the energy is released, so that the current flowing through the power inductor in the energy release period decreases in magnitude and is smaller than the current flowing through the energy storage period in the rising direction, resulting in the current flowing through the power inductor rapidly increasing in a superimposed manner. Although the charging speed of this embodiment is particularly fast, the magnitude of the drop of the current flowing through the power inductor during the energy release phase is always changed along with the change of V2, so that the driving control module has difficulty in controlling the magnitude of the current flowing through the power inductor, and only a power inductor with a particularly large rated current can be used, which means a particularly high component cost.
In one embodiment, the duty cycle of the PWM signal increases with an increase in the actual voltage of the energy storage capacitor, and the duty cycle of the PWM signal is sufficiently large to operate the boost module in the continuous conduction mode, that is, the sum of T1 plus T2 in the volt-second formula V1 × T1 — V2 × T2 is equal to the period of the PWM signal. In another embodiment, the duty cycle of the PWM signal increases with the increase of the actual voltage of the energy storage capacitor, and the inductance of the power inductor is used to be large enough to operate the boost module in the continuous conduction mode.
In some embodiments, the driving control module is configured to control the boosting module to operate in a discontinuous Conduction Mode through the PWM signal, where the discontinuous Conduction Mode is a DCM Mode, i.e., a discontinuous Conduction Mode. The PWM signal enters the next PWM cycle after the current through the rectifier diode drops to 0 during the energy discharge of the power inductor.
In one embodiment, the duty ratio of the PWM signal increases with an increase in the actual voltage of the energy storage capacitor, and the duty ratio of the PWM signal is small enough to operate the boost module in the discontinuous conduction mode. In another embodiment, in an early stage of charging, the duty ratio of the PWM signal is increased with an increase of the actual voltage of the energy storage capacitor, and the duty ratio of the PWM signal is small enough, and in a later stage of charging, the PWM signal is kept unchanged, so that the boost module operates in a discontinuous conduction mode, and limits the magnitude of the current flowing through the power inductor, which enables the control circuit to use the power inductor with a smaller rated current in some applications, although the charging speed is slower, and reduces the component cost.
According to the volt-second formula V1T 1V 2T 2, in any case, once the boost module is operated in the continuous conduction mode, the drive control module needs to control T1 according to the change of V2, otherwise the problem of current superposition rise is caused, and the sum of T1 plus T2 is exactly equal to the PWM period, which is the most reasonable control scheme. However, this is not much different than the embodiment where the boost module operates in discontinuous conduction mode and the sum of T1 plus T2 tends to be equal to the period of the PWM signal. If a more complex control scheme is used, the sum of T1 plus T2 is greater than the period of the PWM signal in the early stage of charging, and then the sum of T1 plus T2 is equal to the period of the PWM signal in the later stage of charging, in some applications, the rated current of the power inductor may be more fully utilized to accelerate the charging speed of the energy storage capacitor, but considering the huge workload caused by application-by-application optimization and the influence of program complexity on system reliability, these control schemes are not preferable for making the effect of the boost module operating in the continuous conduction mode insignificant.
The driving control module is electrically connected with the energy storage capacitor, and the output end of the driving control module is electrically connected with the VOL signal input end of the driving control module; the voltage acquisition module is used for acquiring the voltage of the energy storage capacitor and transmitting the voltage to the drive control module through the VOL signal input end; the driving control module is also used for carrying out analog-to-digital conversion on the voltage of the energy storage capacitor in real time. The drive control module, the boosting module, the trigger discharging module and the voltage sampling module are core parts of digital charge and discharge management and are used for replacing the traditional analog circuit scheme of charging based on the self-oscillation principle and automatic discharging based on trigger voltage or current. Firstly, the driving control module controls the boosting module to charge the energy storage capacitor through a self-contained PWM peripheral at a working frequency above 31.25kHz, and then carries out real-time analog-to-digital conversion on a signal fed back by the voltage acquisition module through a self-contained ADC peripheral at a conversion rate above 31.25kHz, and the driving control module also sends an analog-to-digital conversion result to a special algorithm unit to adjust the duty ratio of the PWM signal in real time, so that the energy storage capacitor is charged to a target voltage value at the fastest speed on the premise that the peak current flowing through an inductor during energy storage does not exceed a rated service condition. Then, the driving control module discharges the energy storage capacitor through the trigger discharge module, so that a discharge arc is formed.
Preferably, the boost power supply device further comprises a power supply module, an input end of the power supply module is electrically connected with a power supply, an output end of the power supply module is electrically connected with the power inductor, and the power supply module is used for supplying power to the boost module. Specifically, the power supply is a direct current power supply.
Optionally, the control terminal of the power supply module is electrically connected with the PWR signal output terminal of the drive control module; the drive control module is further used for controlling the power supply module to stop supplying power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor exceeds a preset charging target voltage; and the power supply module is also used for controlling the power supply module to supply power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor does not exceed a preset charging target voltage. In one embodiment, before the energy storage capacitor is charged each time, the driving control module may check the voltage of the energy storage capacitor, and if it is found that the voltage of the energy storage capacitor is greater than a certain value, for example, the voltage of the energy storage capacitor is too high, for example, when 12V is input, the voltage of the energy storage capacitor is higher than 25V, it is proved that the input voltage is too high, which may affect the control of the PWM algorithm on the maximum value of the charging current, it is proved that the power supply line of the voltage boosting module has failed, and the driving control module may stop the ignition task and give an alarm. If the drive control module finds that the voltage of the energy storage capacitor is not abnormal, the drive control module outputs a high-level PWR signal to the power supply module, so that the power supply module is switched on.
The power supply module is characterized by further comprising an overcurrent detection module, wherein the input end of the overcurrent detection module is electrically connected with a power supply, the output end of the overcurrent detection module is electrically connected with the input end of the power supply module, and the control end of the overcurrent detection module is electrically connected with the TST signal input end of the drive control module; the overcurrent detection module is used for inputting a TST effective level to a TST signal input end of the drive control module when the power supply circuit is in overcurrent; the drive control module is used for controlling the power supply module to stop supplying power to the boosting module through the PWR signal output end when the voltage of the energy storage capacitor is lower than a preset lower limit threshold and/or the TST effective level is received. In one embodiment, if the voltage of the energy storage capacitor is too low, for example, the voltage of the energy storage capacitor is less than 15V at 12V input, it proves that either the input voltage is too low or the subsequent circuit is abnormal. When the input voltage is too low, the charging current cannot reach the designed value, and the discharging frequency cannot be ensured; when the rear-stage circuit is abnormal, for example, only one of the switch tube of the boosting module and the thyristor of the trigger discharging module is short-circuited, the voltage of the energy storage capacitor is zero, and the driving control module needs to cut off direct current power supply so as to prevent the power supply from being short-circuited. In this embodiment, the TST active level is a low level, and if the control end of the over-current detection module outputs the TST active level of the low level, it can basically determine that there is a short circuit in the switching tube of the boost module or the thyristor triggering the discharge module. No matter the voltage of the energy storage capacitor is abnormal or the control end output by the overcurrent detection module outputs a low-level TST effective level, the drive control module immediately outputs a low-level PWR signal to cut off the power supply module after confirming the fault, and the ignition task is stopped and an alarm is given.
In some embodiments, the overcurrent detection module further comprises an automatic power-off module, an input end of the automatic power-off module is electrically connected with the control end of the overcurrent detection module, and an output end of the automatic power-off module is electrically connected with the control end of the power supply module; the automatic power-off module is used for outputting a power-off signal to the control end of the power supply module when receiving the TST effective level; the power supply module is used for stopping supplying power to the boosting module after receiving the power-off signal. When the control end output by the over-current detection module outputs a low-level TST effective level, the power supply module is cut off through the drive control module, the power supply module is also cut off through the automatic power-off module, and the reliability is improved through double-line control.
It is worth to say, still include step-down voltage regulator module, the input of step-down voltage regulator module is connected with the power electricity, the output of step-down voltage regulator module is connected with the power supply input electricity of drive control module, step-down voltage regulator module is used for supplying power for drive control module after stepping down to the voltage of power. In order to accelerate the charging speed, the boosting module tends to use a higher voltage power supply, and the operating voltage of the driving control module is lower than that of the boosting module, so that the voltage is required to be reduced by the buck regulator module. In addition, the voltage reduction and stabilization module also has a voltage stabilization function, so that the voltage input to the drive control module is kept stable, and the drive control module can stably work.
Optionally, the driving control module is a microcontroller MCU, an 8MHz oscillator of the driving control module is used to drive a system clock, and the PWM signal is an 8-bit PWM signal. According to the relation of the voltage and the current of the inductor, U is the voltage difference between two ends of the inductor during the energy storage period of the power inductor, the value of the voltage difference is equal to the input voltage under an ideal circuit model, L is the inductance value of the power inductor, di is the change value of the current flowing through the power inductor during the energy storage period, dt is the duration of the high level of the PWM signal, and the ratio of dt to the PWM period is the duty ratio of the PWM signal, therefore, it can be inferred that when the boost module operates in the discontinuous conduction mode, the initial current flowing through the power inductor during the energy storage period is 0, the peak current is Ip, and Ip is constant, di is constant, L is reduced along with the reduction of dt, dt is reduced, i.e. T1 is reduced, T2 is also reduced, so that the period of the PWM signal is also reduced, i.e. the inductance required by the higher operating frequency of the PWM signal is smaller, and the cost of the inductor is lower, in the present embodiment, the PWM frequency is selected as high as possible. Similarly, for cost reasons, the control circuit of the digital pulse igniter according to the embodiment of the present invention selects the low-end microcontroller MCU, which has an 8MHz oscillator for the system clock, and the maximum operating frequency of the 8-bit PWM signal is 8000000/(2^8) ═ 31.25 kHz. Reducing the number of bits of the PWM signal may result in a higher PWM frequency, but at the expense of control accuracy, selecting a microcontroller MCU with a higher frequency may also increase the PWM frequency, but at a higher cost. In addition, the instruction cycle of the microcontroller MCU with an oscillator of 8MHz at the low end, which is equivalent to 32us at 31.25kHz, is often 0.5us, and 32us is only enough to execute 64 instructions at most, and when the judgment statement needs to jump, an extra instruction cycle is needed, so that the number of executable instructions is less, and in addition, the interrupt of in and out is time-consuming, which requires a programmer to write highly optimized software code with very fast execution speed. When the control circuit of the digital pulse igniter of the embodiment of the utility model uses the microcontroller MCU with the low-end oscillator with 8MHz, the PWM frequency of 31.25kHz is already the optimal selection, the frequency is continuously increased, the reduction of the inductance cost is not obvious, and the adjustment of the duty ratio once in each PWM period is difficult to realize.
In the embodiment shown in fig. 2 and 3, the principle of the control circuit of the digital pulse igniter is as follows: the drive control module can output PWM signals to control the boosting module to charge the energy storage capacitor, and the VOL signal input end of the drive control module tracks the voltage of the energy storage capacitor in real time through the voltage acquisition module until the energy storage capacitor is charged to a target voltage value. Then, the driving control module stops outputting the PWM signal, that is, turns off the boost module, outputs the PWR signal at a low level, and turns off the power supply module, and then the TRI signal output terminal of the driving control module outputs a TRI trigger signal with a fixed high level duration to the trigger discharge module, so as to trigger the energy storage capacitor to discharge instantaneously, thereby forming a discharge arc. The arrows in fig. 2 indicate the signal transmission direction.
The response speed of the TST effective level generated by the overcurrent detection module is higher than the speed of the driving control module for detecting the VOL signal, and the TST effective level and the VOL signal are used together for circuit self-checking performance and system reliability enhancement.
The low level duration of the PWR signal of this embodiment is also controlled, and the driving control module is clocked by a self-contained timer to control the discharging frequency, for example, the time consumed by charging is 4ms, and the required discharging frequency is 200Hz, so the low level duration of the PWR signal is about 1ms, and if the required discharging frequency is 100Hz, the low level duration of the PWR signal is about 6 ms. This also means that the control circuit of the digital pulse igniter of the present embodiment can increase or decrease the discharge frequency by merely modifying the configuration of the timer. Of course, the core of the random adjustment of the discharge frequency is that the charging speed is fast enough, which depends mainly on the power supply voltage and the inductance selected by the boost module, and also depends on the PWM control algorithm of the driving control module. The control circuit of the digital pulse igniter of the embodiment can realize shorter charging time and higher discharging frequency by replacing the inductor selected by the boosting module and adjusting the algorithm unit in the program through a related calculation formula, for example, ignition power of more than 10W can be realized by selecting an i-shaped inductor of 1016 packaged 150uH under 24V input.
The more stable the trigger voltage is, the more stable the maximum ignition distance of the igniter, which is a core parameter of the pulse igniter. The trigger voltage value of the traditional trigger tube discharge scheme is relatively fixed, the precision can only reach 5% level, and the specific trigger voltage value mainly depends on the type of the selected trigger tube, for example, K1800 of Littelfuse corresponds to 175V, and K1500 corresponds to 150V; the batch consistency of the trigger voltage value of the traditional silicon controlled rectifier discharging scheme is worse, and no matter the trigger circuit based on 1N4148 reverse breakdown voltage or the trigger circuit based on a voltage stabilizing tube, because resistors are connected in series in the circuit, the specific trigger voltage value is also influenced by the trigger current parameters of the silicon controlled rectifier, and various parameter errors are overlapped and are also easily influenced by the environment temperature. In addition, when the ignition power needs to be improved, thanks to the digital control technology, the control circuit of the digital pulse igniter in the embodiment of the utility model has quite high flexibility, even under the premise of not changing a hardware circuit, the ignition power can be doubled by changing software, the ignition power needs to be improved by an analog circuit, the whole circuit parameters need to be recalculated and adjusted, and the adjustment of the transformer and the switching circuit usually involves the redesign of a PCB, the whole process is quite complex, and the cost is only higher.
Compared with the scheme that the PWM technology is used for charging the energy storage capacitor through the boosting of the transformer based on the Flyback principle, the embodiment of the utility model can realize the same ignition power by only using the common small-size I-shaped inductor. The I-shaped inductor has simple manufacturing process and strong universality, is much lower than the boosting transformer such as EE13 in price and has higher reliability. In addition, the I-shaped inductor only has one winding and is not isolated, so that the self-checking of the circuits of the low-voltage side and the high-voltage side can be completed only by one feedback signal, and the transformer has two windings which are isolated from each other and need two feedback signals. Therefore, when the scheme of boosting the voltage by adopting the transformer is adopted to carry out circuit self-checking, the circuit is more complex, and more resources are needed for driving the control module.
In addition, another technical scheme for improving ignition power is adopted in the prior art, 24V power supply is adopted, firstly, the voltage is boosted to be more than 200V through a Boost type switching circuit controlled by a driving control module, then, an oscillation square wave with the amplitude of 200V and the duty ratio of 50% is generated through a high-voltage switching tube controlled by the driving control module, then, an energy storage capacitor is charged through a resistor during the high voltage period of the square wave, and finally, the energy storage capacitor is discharged through a silicon controlled rectifier controlled by the driving control module. The charging and discharging of the scheme are controlled by the drive control module, the problem that the traditional analog circuit cannot reliably cut off the trigger discharging circuit when the discharging frequency is too high to cause non-ignition is solved, and the trigger voltage value is also accurate as long as the boosted voltage value is stable and accurate, but the scheme has the defects that the time for charging is only half, the efficiency of a mode for charging the energy storage capacitor through the resistor is low, the higher the ignition power is, the more the resistor generates heat, the circuit is complex, the cost is high, and the reliability is low. It is difficult to achieve ignition powers above 3W with this solution. Compared with the existing scheme, the embodiment of the utility model has a simpler circuit structure, only one high-voltage-resistant element is needed in the charging part, the requirement on the resource of the driving control module is lower, and only single PWM is needed. This prior art scheme requires multiple high voltage tolerant components and two PWM paths, one for boosting and the other for forming a square wave. The control circuit of the digital pulse igniter of the embodiment of the utility model has higher efficiency when the same ignition power is realized, and is not limited by the RC charging time constant.
It is worth to be noted that, in the existing scheme, 24VDC power is adopted, a Boost type switch circuit is used for directly charging an energy storage capacitor, but the conduction of a trigger tube at the moment of discharging easily causes a short circuit of a power supply, a designer has to select an i-shaped inductor which has a very large size and needs to be specially customized and has a large inductance, and a trigger tube which can maintain a current Holding current to reach 150mA, and then the cutoff speed of the trigger tube is expected to be fast enough. This solution is certainly problematic in applications where the actual holding current of the trigger tube is low, as long as the discharge time is encountered. According to the formula of U-L ═ di/dt, the inductor current rises from 0 to 30mA, only 12.5us is needed under the inductance of 10mH at 24V input, the first cycle of the discharge high voltage is usually greater than 12us, and as long as the actual holding current of the trigger tube is lower than 30mA, the trigger tube cannot be cut off, and the power supply can be short-circuited. Moreover, this kind of scheme uses the trigger pipe that cutoff speed is faster than the silicon controlled rectifier, but the trigger pipe usually can only work below 60Hz, so this kind of current scheme is also difficult to accomplish 3W level ignition power. Moreover, the trigger voltage of this conventional scheme is still based on the specification parameters of the device itself, and the accuracy is limited. Compared with the existing scheme, the embodiment of the utility model has no risk of short-circuit power supply, the ignition power is not limited by the specification parameters of the trigger tube, and the precision of the ignition power is higher. The control circuit of the digital pulse igniter only needs one low-cost I-shaped inductor of 220uH packaged by 0810, and 4W ignition power with the precision reaching 5% level can be realized under the input of 12V. Compared with the traditional pulse igniter with a pure analog circuit, the pulse igniter realizes the ignition power more than 10 times under the conditions of small total cost difference and smaller PCB size.
In the description herein, references to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example" or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
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| CN113655751A (en) * | 2021-09-22 | 2021-11-16 | 佛山市顺德区锜科电子科技有限公司 | A control circuit of a digital pulse igniter |
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| CN113655751A (en) * | 2021-09-22 | 2021-11-16 | 佛山市顺德区锜科电子科技有限公司 | A control circuit of a digital pulse igniter |
| CN113655751B (en) * | 2021-09-22 | 2025-01-07 | 佛山市顺德区锜科电子科技有限公司 | A control circuit for a digital pulse igniter |
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