CN209904485U - Constant power control system of parking heater spark plug - Google Patents
Constant power control system of parking heater spark plug Download PDFInfo
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- CN209904485U CN209904485U CN201920086038.3U CN201920086038U CN209904485U CN 209904485 U CN209904485 U CN 209904485U CN 201920086038 U CN201920086038 U CN 201920086038U CN 209904485 U CN209904485 U CN 209904485U
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Abstract
The utility model provides a constant power control system of parking heater spark plug, the fifth module carries out the proportional-integral processing through the pulse width modulation signal to little the control unit output and the voltage signal of the spark plug of fourth module output, obtain the control deviation signal, and then influence the pulse width modulation signal of sixth module output through the control deviation signal, then the opening voltage of first module also receives the influence thereupon, change the on-time of second module through changing the duty cycle of first module opening voltage, then the second module carries out the pulse width with outside high level and evens up the processing, for the spark plug provides a steady direct current voltage; therefore, the pulse width modulation signal of the constant power control system of the embodiment is not directly loaded on the spark plug before the voltage enters the spark plug, so that a constant direct current voltage is loaded at two ends of the spark plug, instantaneous voltage impact is avoided, and the service life of the spark plug is prolonged.
Description
Technical Field
The utility model belongs to the technical field of power control, especially, relate to a constant power control system of parking heater spark plug.
Background
The parking heater is an independently working heating system, does not need to start a vehicle engine, can be started to work by utilizing a vehicle-mounted 24-volt or 12-volt storage battery, can supply heat for a vehicle cab, and is used for supplying heat in a vehicle in cold seasons. The heater can preheat the engine before starting while supplying heat to the cab, and solves the problems of difficult cold start and high emission in low-temperature start of the vehicle. And a spark plug in the parking heater is a key element for ensuring the normal ignition success of the heater. The spark plug can generate a large current of more than 20 amperes when in operation, and if the control is improper, the normal operation of other circuits of the controller can be influenced, and the service life of the spark plug can be seriously shortened.
The parking heater spark plug exhibits a non-linear resistive load characteristic with a resistance that typically varies between 0.8 ohms and 6.0 ohms, and requires 60-80 watts of spark plug power for proper ignition. For example, a spark plug used on a 24 volt vehicle is rated at 18 volts, and if the rated voltage is applied initially, the current can reach more than 20 amps, which can produce a large current surge. The non-linear characteristic of the spark plug is represented by non-linear increase of resistance with temperature increase, so in order to avoid current surge and prolong the service life of the spark plug, voltage soft start control is generally adopted to control the current when the ignition plug works so as to prevent excessive current surge.
In the prior art, the spark plug is controlled by adopting a constant voltage technology of PWM control and matching with soft start to control the working current of the spark plug. The control method can ensure that the average value or the effective value of the voltage loaded on the spark plug is a constant voltage, but the working current of the spark plug cannot be controlled smoothly, although the voltage soft start can inhibit the current impact of the spark plug, the working current of the spark plug is still unstable due to the nonlinearity of the resistance of the spark plug during the working process, and the current change is large. In addition, the influence of transient voltage surges on the service life of the spark plug cannot be avoided.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem, the utility model provides a parking heater spark plug's constant power control system for the loading is a invariable DC voltage at spark plug both ends, has avoided instantaneous voltage impact, makes spark plug both ends voltage steady, is favorable to prolonging spark plug's life.
A constant power control system of a parking heater spark plug comprises a first module, a second module, a third module, a fourth module, a fifth module, a sixth module and a micro control unit;
the first module comprises a triode Q1, wherein the base of the triode Q1 is connected to the pulse width modulation control signal output by the sixth module, and the collector outputs a starting voltage to the second module;
the second module comprises an NMOS transistor Q2 and an inductor L1, wherein the grid electrode of the NMOS transistor Q2 is connected with the starting voltage, the drain electrode of the NMOS transistor Q2 is connected with an external power supply, the source electrode of the NMOS transistor Q2 is connected with one end of the inductor L1, and the other end of the inductor L1 is connected with the spark plug;
the third module comprises a resistor R5 and an amplifying circuit, wherein one end of the resistor R5 is grounded, and the other end of the resistor R5 is connected with the spark plug and is used for sampling the current of the spark plug; the amplifying circuit is used for amplifying the current of the spark plug sampled by the resistor R5 and then feeding the current back to the micro control unit;
one end of the resistor R4 of the fourth module is connected with the spark plug and is used for connecting the voltage of the spark plug, the other end of the resistor R6 is connected with the resistor R6, and the other end of the resistor R6 is grounded; one end of the resistor R4 connected with the resistor R6 is used for outputting the acquired voltage of the spark plug to the fifth module and the micro control unit;
the fifth module comprises resistors R13, R14 and R16, a capacitor C11 and an operational amplifier U1B, and the resistances of the resistor R16 and the resistor R13 are equal, wherein one end of the resistor R16 is used as a first input end of the fifth module and is used for accessing a pulse width modulation signal output by the micro control unit, and the other end of the resistor R16 is connected with a non-inverting input end of the operational amplifier U1B; one end of the resistor R13 is connected with the inverting input end of the operational amplifier U1B, and the other end of the resistor R13 is used as the second input end of the fifth module and is used for connecting the voltage output by the fourth module; the capacitor C11 and the resistor R14 are connected in series, one series end is connected with the output end of the operational amplifier U1B, and the other series end is connected with the inverting input end of the operational amplifier U1B; the output end of the operational amplifier U1B is used for outputting a control deviation signal;
the sixth module comprises an operational amplifier U1C, wherein the non-inverting input terminal of the operational amplifier U1C is used for accessing a sawtooth wave signal given by the micro control unit, the inverting input terminal is used for accessing a control deviation signal output by the fifth module, and the output terminal is used for outputting a pulse width modulation signal;
the micro control unit is used for obtaining the current power of the spark plug according to the current and the voltage, and then adjusting the duty ratio of the pulse width modulation signal output to the fifth module according to the current power and the required power.
Furthermore, the first module also comprises resistors R1-R3 and a diode D1;
the base electrode of the triode Q1 is respectively connected with a resistor R1 and a resistor R2, wherein the other end of the resistor R1 is used as the input end of the first module and is connected with the pulse width modulation control signal output by the sixth module, and the other end of the resistor R2 is grounded; the emitter of the transistor Q1 is grounded, the collector is connected to the cathode of the diode D1 and the resistor R3, respectively, wherein the anode of the diode D1 is grounded, and the other end of the resistor R3 is used for outputting the turn-on voltage.
Further, the second module further comprises capacitors C1, C2 and a diode D2;
the source of the NMOS transistor Q2 is connected to the anode of the capacitor C1 and the cathode of the diode D2, wherein the anode of the diode D2 is grounded, the cathode of the capacitor C1 is grounded, the other end of the inductor L1 is connected to the anode of the capacitor C2, and the cathode of the capacitor C2 is grounded.
Further, the external power supply is 24V.
Further, the amplifying circuit of the third module comprises resistors R8-R11, capacitors C3-C6 and an operational amplifier U1A;
one end of the resistor R9 is connected with the spark plug and is used for connecting the current of the spark plug, the other end of the resistor R9 is connected with the non-inverting input end of the operational amplifier U1A, and meanwhile, the non-inverting input end of the operational amplifier U1A is grounded after being connected with the capacitor C4; the output end of the operational amplifier U1A is connected with one end of a resistor R11, the other end of the resistor R11 is used as the output end of a third module and is used for feeding back the current of the spark plug to the micro control unit, meanwhile, the output end of the resistor R11 is also connected with one end of a capacitor C6, and the other end of the capacitor C6 is grounded; the capacitor C5 is connected with the resistor R10 in parallel, and the two parallel ends are respectively connected with the output end and the inverting input end of the operational amplifier U1A; the capacitor C3 is connected in parallel with the resistor R8, one parallel end is connected with the inverting input end of the operational amplifier U1A, and the other parallel end is grounded.
Further, the fourth module further comprises a resistor R7 and capacitors C9 and C10;
the ungrounded end of the resistor R6 is respectively connected with one ends of a capacitor C9 and a resistor R7, meanwhile, the other end of the capacitor C9 is grounded, and the other end of the resistor R7 is used as a first output end of the fourth module and used for feeding back the voltage of the spark plug to the micro control unit; the first output terminal of the resistor R7 is further connected to one terminal of the capacitor C10, and the other terminal of the capacitor C10 is grounded.
Further, the fifth module further comprises resistors R12 and R15, and capacitors C7 and C8;
the capacitor C8 and the resistor R15 are connected in series and then connected in parallel at two ends of the resistor R16, and one end of the capacitor C8 and one end of the resistor R15, which are not connected with the resistor R16, are grounded; the capacitor C7 is connected in parallel with the resistor R12, one of which is connected in parallel with the inverting input terminal of the operational amplifier U1B, and the other is connected in parallel with the ground.
Further, the sixth module comprises resistors R17-R20;
one end of the resistor R17 is connected with the non-inverting input end of the operational amplifier U1C, and the other end of the resistor R17 is used as the first input end of the sixth module and is used for accessing a sawtooth wave signal given by the micro control unit; one end of the resistor R18 is connected to the inverting input terminal of the operational amplifier U1C, and the other end of the resistor R18 is used as the second input terminal of the sixth module and is used for accessing the control deviation signal output by the fifth module; one end of the resistor R19 is connected with the non-inverting input end of the operational amplifier U1C, and the other end is grounded; one end of the resistor R20 is connected with the inverting input end of the operational amplifier U1C, and the other end is connected with high level.
Has the advantages that:
the utility model provides a constant power control system of parking heater spark plug, the fifth module carries out the proportional-integral processing through the pulse width modulation signal to little the control unit output and the voltage signal of the spark plug of fourth module output, obtain control deviation signal, and then influence the pulse width modulation signal of sixth module output through control deviation signal, then the opening voltage of first module also receives the influence thereupon, change the on-time of second module through changing the duty cycle of first module opening voltage, then the second module carries out the pulse width with external power supply and evens up the processing, for the spark plug provides a steady direct current voltage; therefore, the pulse width modulation signal of the constant power control system of the embodiment is not directly loaded on the spark plug before the voltage enters the spark plug, so that the constant direct current voltage is loaded at two ends of the spark plug, instantaneous voltage impact is avoided, the voltage at two ends of the spark plug is stable, and the service life of the spark plug is prolonged.
Drawings
Fig. 1 is a schematic block diagram of a constant power control system of a parking heater spark plug according to the present invention;
fig. 2 is a schematic circuit diagram of a constant power control system of a parking heater spark plug according to the present invention.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
Example one
Referring to fig. 1, a schematic block diagram of a constant power control system of a parking heater spark plug according to the present embodiment is shown.
A constant power control system of a parking heater spark plug comprises a first module, a second module, a third module, a fourth module, a fifth module, a sixth module and a micro control unit;
the first module comprises a triode Q1, wherein the base of the triode Q1 is used for connecting the pulse width modulation control signal output by the sixth module, and the collector of the triode Q1 is used for outputting a turn-on voltage to the second module;
the second module comprises an NMOS transistor Q2 and an inductor L1, wherein the gate of the NMOS transistor Q2 is used for connecting the starting voltage, the drain is used for connecting an external power supply, the source is used for connecting one end of the inductor L1, and the other end of the inductor L1 is connected with the spark plug and used for providing a stable direct current voltage for the spark plug;
the third module comprises a resistor R5 and an amplifying circuit, wherein one end of the resistor R5 is grounded, and the other end of the resistor R5 is connected with the spark plug and is used for sampling the current of the spark plug; the amplifying circuit is used for amplifying the current of the spark plug sampled by the resistor R5 and then feeding the current back to the micro control unit;
one end of the resistor R4 is connected with the spark plug and is used for connecting the voltage of the spark plug, the other end of the resistor R4 is connected with the resistor R6, and the other end of the resistor R6 is grounded; one end of the resistor R4 connected with the resistor R6 is used for outputting the voltage of the spark plug to the fifth module and the micro control unit;
the fifth module comprises resistors R13, R14 and R16, a capacitor C11 and an operational amplifier U1B, and the resistances of the resistor R16 and the resistor R13 are equal, wherein one end of the resistor R16 is used as a first input end of the fifth module and is used for accessing a pulse width modulation signal output by the micro control unit, and the other end of the resistor R16 is connected with a non-inverting input end of the operational amplifier U1B; one end of the resistor R13 is connected with the inverting input end of the operational amplifier U1B, and the other end of the resistor R13 is used as the second input end of the fifth module and is used for connecting the voltage output by the fourth module; the capacitor C11 and the resistor R14 are connected in series, one series end is connected with the output end of the operational amplifier U1B, and the other series end is connected with the inverting input end of the operational amplifier U1B; the output end of the operational amplifier U1B is used for outputting a control deviation signal;
the sixth module comprises an operational amplifier U1C, wherein the non-inverting input terminal of the operational amplifier U1C is used for receiving a sawtooth wave signal given by the micro control unit, the inverting input terminal is used for receiving the control deviation signal output by the fifth module, and the output terminal is used for outputting a pulse width modulation signal.
The working principle of the constant power control system for the parking heater spark plug provided by the embodiment is described as follows:
the first module is used for providing starting voltage for the second module;
the second module is used for accessing an external power supply, and performing pulse width leveling processing on the external power supply when the starting voltage is accessed, so as to provide stable direct-current voltage for the spark plug;
the third module is used for sampling the current of the spark plug and feeding the current back to the micro control unit;
the fourth module is used for sampling the voltage of the spark plug and feeding the voltage back to the micro control unit and the fifth module;
the micro control unit is used for obtaining the current power of the spark plug according to the current and the voltage, and then adjusting the duty ratio of the pulse width modulation signal output to the fifth module according to the current power and the required power, wherein if the current power is equal to the required power, the duty ratio is kept unchanged, if the current power is lower than the required power, the duty ratio is reduced, and if the current power is higher than the required power, the duty ratio is increased;
the fifth module is used for receiving the pulse width modulation signal output by the micro control unit and the voltage output by the fourth module, performing proportional integral on the difference value of the pulse width modulation signal and the voltage output by the micro control unit to obtain a control deviation signal, and outputting the control deviation signal to the sixth module;
the sixth module is used for receiving the control deviation signal and a sawtooth wave signal given by the micro control unit and generating a pulse width modulation signal according to the size of the control deviation signal and the sawtooth wave signal;
the first module is used for adjusting the duty ratio of the starting voltage according to the pulse width modulation signal output by the sixth module, controlling the conduction time of the second module and adjusting the voltage at two ends of the spark plug so that the power of the spark plug is constant.
It should be noted that, after receiving the sampling current output by the third module and the sampling voltage output by the fourth module, the micro control unit can obtain the current power of the spark plug. The sawtooth wave signal output by the micro control unit is fixed and unchanged, and the pulse width modulation signal is adjusted according to the current power of the spark plug, wherein if the current power is equal to the required power of the spark plug, the pulse width modulation signal output by the micro control unit is kept unchanged, and the control deviation signal is also kept unchanged, wherein the control deviation signal is a direct current voltage signal, the duty ratio of the pulse width modulation signal output by the sixth module is also unchanged, so that the direct current voltage loaded on the spark plug is also kept unchanged, and the power of the spark plug is constant; if the current power is higher than the required power of the spark plug, the duty ratio of the pulse width modulation signal output by the micro control unit is increased, at the moment, a control deviation signal obtained by proportional integration of the difference value of the pulse width modulation signal output by the micro control unit and the sampling voltage output by the fourth module is increased, the sixth module receives the control deviation signal and the sawtooth wave signal, wherein if the sawtooth wave signal is greater than the control deviation signal, the sixth module outputs a high level, otherwise, a low level is output, therefore, under the condition that the control deviation is increased, the duty ratio of the pulse width modulation signal output by the sixth module is reduced, the duty ratio of the starting voltage output by the first module is reduced, the conduction time of the second module is shortened, and the direct current voltage of the finally loaded spark plug is reduced, so that the current power of the spark plug is reduced, maintaining the required power; similarly, if the current power is lower than the required power of the spark plug, the duty ratio of the pulse width modulation signal output by the micro control unit is reduced, so that the current power of the spark plug is improved, and the constant power control of the spark plug is realized.
Therefore, in the fifth module of the present embodiment, a control deviation signal is obtained by performing proportional-integral processing on a pulse width modulation signal output by the micro control unit and a voltage signal of the spark plug output by the fourth module, and then the pulse width modulation signal output by the sixth module is influenced by the control deviation signal, so that the turn-on voltage of the first module is also influenced, and then the duty ratio of the turn-on voltage of the first module is changed to change the turn-on time of the second module, and then the second module performs pulse width leveling processing on the external power supply to provide a stable dc voltage for the spark plug; therefore, the pulse width modulation signal of the constant power control system of the embodiment is not directly loaded on the spark plug before the voltage enters the spark plug, so that the constant direct current voltage is loaded at two ends of the spark plug, instantaneous voltage impact is avoided, the voltage at two ends of the spark plug is stable, and the service life of the spark plug is prolonged.
Example two
Based on the above embodiments, the present embodiment provides a specific implementation of the constant power control system of the parking heater spark plug. Referring to fig. 2, a schematic circuit diagram of a constant power control system of a parking heater spark plug according to the present embodiment is shown.
A constant power control system for a parking heater spark plug includes first to sixth modules.
First, a specific implementation of the first module is described.
The first module comprises resistors R1-R3, a triode Q1 and a diode D1;
the base electrode of the triode Q1 is respectively connected with a resistor R1 and a resistor R2, wherein the other end of the resistor R1 is used as the input end of the first module and is connected with the pulse width modulation control signal output by the sixth module, and the other end of the resistor R2 is grounded; the emitter of the transistor Q1 is grounded, the collector is connected to the cathode of the diode D1 and the resistor R3, respectively, wherein the anode of the diode D1 is grounded, and the other end of the resistor R3 is used for outputting the turn-on voltage.
The resistor R1 and the resistor R3 are current limiting resistors, the resistor R2 is a pull-down resistor, and the diode D1 is a zener diode.
A specific implementation of the second module is described below.
The second module comprises an NMOS tube Q2, an inductor L1, a diode D2 and capacitors C1 and C2;
the grid electrode of the NMOS tube Q2 is used as the input end of the second module and is connected with the starting voltage of the first module; the drain of the NMOS tube Q2 is connected with an external power supply, the source is respectively connected with one end of an inductor L1, the anode of a capacitor C1 and the cathode of a diode D2, wherein the anode of the diode D2 is grounded, the cathode of the capacitor C1 is grounded, the other end of the inductor L1 is connected with the anode of a capacitor C2, the cathode of the capacitor C2 is grounded, and meanwhile, one end of the inductor L1, which is connected with the capacitor C2, is also connected with the spark plug and used for providing stable direct current voltage for the spark plug.
The diode D2 is a freewheeling diode.
Optionally, the external power supply is 24V.
Therefore, the constant power control system provided by the embodiment is different from the traditional constant voltage control in that the voltage wave output by the PWM is flattened by matching the inductor and the capacitor, so that a constant direct current voltage is loaded at two ends of the spark plug instead of a pulse width modulation waveform, instantaneous voltage impact is avoided, the voltage at two ends of the spark plug is stable, and the service life of the spark plug is prolonged.
A specific implementation of the third module is described below.
The third module comprises a resistor R5 and an amplifying circuit;
one end of the resistor R5 is grounded, and the other end of the resistor R5 is connected with the spark plug and is used for sampling the current of the spark plug; the amplifying circuit is used for amplifying the current of the spark plug sampled by the resistor R5 and then feeding the current back to the micro control unit;
the amplifying circuit comprises resistors R8-R11, capacitors C3-C6 and an operational amplifier U1A;
specifically, one end of the resistor R9 is connected to the spark plug for receiving the current of the spark plug, the other end of the resistor R9 is connected to the non-inverting input terminal of the operational amplifier U1A, and meanwhile, the non-inverting input terminal of the operational amplifier U1A is grounded after being connected to the capacitor C4; the output end of the operational amplifier U1A is connected with one end of a resistor R11, the other end of the resistor R11 is used as the output end of a third module and is used for feeding back the current of the spark plug to the micro control unit, meanwhile, the output end of the resistor R11 is also connected with one end of a capacitor C6, and the other end of the capacitor C6 is grounded; the capacitor C5 is connected with the resistor R10 in parallel, and the two parallel ends are respectively connected with the output end and the inverting input end of the operational amplifier U1A; the capacitor C3 is connected in parallel with the resistor R8, one parallel end is connected with the inverting input end of the operational amplifier U1A, and the other parallel end is grounded.
It should be noted that the resistor C3, the capacitor R8, the resistor R9, the capacitor C4, the resistor R10, the capacitor C5, the resistor R11, and the capacitor C6 respectively form a resistance-capacitance filter circuit; and the resistance of the resistor R8 is equal to that of the resistor R9, and the amplification factor of the amplifying circuit is the ratio of the resistor R10 to the resistor R8.
A specific implementation of the fourth module is described below.
The fourth module comprises resistors R4, R6, R7 and capacitors C9, C10;
one end of the resistor R4 is connected with the spark plug and is used for connecting the voltage of the spark plug, the other end of the resistor R6, the capacitor C9 and one end of the resistor R7 are respectively connected, meanwhile, the other end of the resistor R6 is grounded, the other end of the capacitor C9 is grounded, and the other end of the resistor R7 is used as a first output end of the fourth module and is used for feeding the voltage of the spark plug back to the micro control unit; the first output end of the resistor R7 is also connected with one end of the capacitor C10, and the other end of the capacitor C10 is grounded; one end of the resistor R4 connected with the resistor R6 is used as a second output end of the fourth module and is used for outputting the voltage of the spark plug to the fifth module.
The resistor R4 and the resistor R6 share the voltage of the connected spark plug; the resistor R7 and the capacitors C9 and C10 form a filter circuit for filtering burrs possibly existing in the voltage divided by the resistor R6 and inputting the burrs into the micro-control unit.
It should be noted that, after receiving the sampling current and the sampling voltage of the spark plug, the micro control unit calculates the current power of the spark plug according to the sampling current and the sampling voltage, and then cooperates with the constant power control system to adjust the voltage at the two ends of the spark plug, so that the power of the spark plug is kept constant.
A specific implementation of the fifth module is described below.
The fifth module comprises resistors R12-R16, capacitors C7, C8, C11 and an operational amplifier U1B, and the resistance values of the resistor R16 and the resistor R13 are equal;
one end of the resistor R16 is used as a first input end of the fifth module and is used for accessing a pulse width modulation signal set by the micro control unit, and the other end of the resistor R16 is connected with a non-inverting input end of the operational amplifier U1B; the capacitor C8 and the resistor R15 are connected in series and then connected in parallel at two ends of the resistor R16, and one end of the capacitor C8 and one end of the resistor R15, which are not connected with the resistor R16, are grounded; one end of the resistor R13 is connected with the inverting input end of the operational amplifier U1B, and the other end of the resistor R13 is used as the second input end of the fifth module and is used for connecting the voltage output by the fourth module; the capacitor C11 and the resistor R14 are connected in series, one series end is connected with the output end of the operational amplifier U1B, and the other series end is connected with the inverting input end of the operational amplifier U1B; the capacitor C7 is connected with the resistor R12 in parallel, one of the capacitors is connected with the inverting input end of the operational amplifier U1B in parallel, and the other parallel end is grounded; the output end of the operational amplifier U1B is used as the output end of the fifth module for outputting the control deviation signal.
It should be noted that the resistor R14, the capacitor C11, and the operational amplifier U1B form a PI regulator, the resistor R16 and the resistor R13 are input resistors, and the ratio of the resistor R14 to the resistor R13 is the amplification factor of proportional adjustment in the PI regulator; the resistor R12, the capacitor C7, the resistor R15 and the capacitor C8 respectively form a resistance-capacitance filter circuit.
A specific implementation of the sixth module is described below.
The sixth module comprises resistors R17-R20 and an operational amplifier U1C;
one end of the resistor R17 is connected with the non-inverting input end of the operational amplifier U1C, and the other end of the resistor R17 is used as the first input end of the sixth module and is used for accessing a sawtooth wave signal given by an external microcontroller; one end of the resistor R19 is connected with the non-inverting input end of the operational amplifier U1C, and the other end is grounded; one end of the resistor R18 is connected to the inverting input terminal of the operational amplifier U1C, and the other end of the resistor R18 is used as the second input terminal of the sixth module and is used for accessing the control deviation signal output by the fifth module; one end of the resistor R20 is connected with the inverting input end of the operational amplifier U1C, and the other end is connected with high level; the output end of the operational amplifier U1C is used as the output end of the sixth module, and is used for outputting a pulse width modulation signal.
The resistor R17 and the resistor R18 are input resistors, the resistor R19 is a pull-down resistor, and the resistor R20 is a pull-up resistor; because the operational amplifier U1C is actually a comparator, when the signal at the non-inverting input terminal is greater than the signal at the inverting input terminal, i.e., the sawtooth signal is greater than the control deviation signal, the operational amplifier U1C outputs a high level, otherwise outputs a low level; therefore, when the micro control unit does not output a sawtooth wave, that is, when the non-inverting input terminal of the operational amplifier U1C has no signal and the inverting input terminal has a signal, the pull-down resistor R19 can ensure that the signal of the non-inverting input terminal of the operational amplifier U1C is smaller than the signal of the inverting input terminal, and then the operational amplifier U1C outputs a low level, and the transistor Q1 in the subsequent first module is not turned on; when the fifth module does not output the control deviation signal, that is, the non-inverting input terminal of the operational amplifier U1C has a signal and the inverting input terminal has no signal, the pull-up resistor R20 can ensure that the signal at the inverting input terminal of the operational amplifier U1C is greater than the signal at the non-inverting input terminal, and then the operational amplifier U1C still outputs a low level, and the transistor Q1 in the subsequent first module is not turned on; therefore, the resistor R20 and the resistor R19 greatly improve the safety and reliability of the whole control system.
In fig. 2, GND refers to a digital ground, VGND refers to a vehicle body ground, and one inductor L2 or one magnetic bead is connected between GND and VGND for isolating the two.
It should be noted that the turn-on voltage generated by the first module is a PWM (Pulse Width Modulation) wave, and the PWM wave controls the on/off of the NMOS transistor Q2 in the second module; and the duty cycle of the turn-on voltage output by the first module is determined by the operational amplifier U1C in the sixth module. The second module is mainly a power switch element NMOS transistor Q2 and its pulse width leveling circuit, and its voltage leveling main element depends on an inductor L1. The third module is used for sampling and feeding back the current of the spark plug, wherein the LOAD LOAD is the spark plug, the resistor R5 is a current feedback sampling resistor, and the current feedback sampling resistor is amplified and isolated by an operational amplifier U1A and then sent to a micro control unit MCU for A/D conversion. The fourth module is a spark plug voltage feedback module, and feeds the flattened voltage back to the MCU after voltage division and filtering. The fifth module is actually an analog PI regulator, and respectively receives a pulse width modulation signal set by the MCU and the partial voltage of the flattened spark plug voltage obtained by the fourth module, and performs proportional integration on the pulse width modulation signal and the partial voltage to obtain a control deviation signal, wherein the control deviation signal is a direct current voltage signal. The sixth module is used for generating a PWM signal for controlling the base of the triode Q1 through the operational amplifier U1C, an input signal at one end of the operational amplifier U1C is a sawtooth wave signal with a certain frequency and a certain amplitude given by the micro control unit MCU, and the other end of the operational amplifier U1C is a PI regulator, namely a control deviation signal output by the fifth module, wherein the amplitude of the sawtooth wave signal needs to meet the requirement that the operational amplifier U1C can output the PWM wave, namely the amplitude of the control deviation signal is smaller than that of the sawtooth wave signal, when the sawtooth wave signal is larger than the control deviation signal, the operational amplifier U1C outputs a high level, and when the sawtooth wave signal is not larger than the control deviation signal, the operational amplifier U1C outputs a low level; that is, if the control deviation signal changes, the duty ratio of the PWM wave output from the operational amplifier U1C changes. When the voltage division of the spark plug is equal to the PWM wave signal set by the MCU, the sixth module outputs the PWM signal with the same frequency as the sawtooth wave signal and constant duty ratio, so that the direct-current voltage output by the second module is ensured to be a constant value, and if the voltage division of the spark plug is unequal to the PWM wave signal set by the MCU, the duty ratio of the PWM signal output by the operational amplifier U1C in the sixth module is changed through the change of a control deviation signal output by a PI regulator, namely the fifth module, so that the constancy of the power of the spark plug is adjusted.
For example, if the current power is lower than the required power of the spark plug, the duty ratio of the pwm signal output by the mcu is reduced, and at this time, the time that the voltage signal at the non-inverting input terminal of the operational amplifier U1B is greater than the sampling voltage output by the fourth module is shortened, so that the control offset signal obtained by proportional integration of the difference between the pwm signal output by the mcu and the sampling voltage output by the fourth module is reduced, and the duty ratio of the pwm signal output by the operational amplifier U1C in the sixth module is increased, so that the on-time of the transistor Q1 in the first module is prolonged, the duty ratio of the output turn-on voltage is also increased, and the on-time of the NMOS transistor Q2 in the second module is prolonged, and the dc voltage of the finally loaded spark plug is increased, so that the current power of the spark plug is increased and kept at the required power.
Therefore, the voltage waveform of the PWM output by the NMOS tube Q2 is flattened into a stable direct-current voltage, so that the stability and the safety of the power supply voltage of the spark plug are ensured; the magnitude of the direct current voltage and the magnitude of the current of the spark plug are sampled by the micro control unit, and the magnitude of the duty ratio of the PWM wave signal set by the micro control unit MCU is adjusted under the condition of ensuring constant power through the operation of the micro control unit, so that the constant power control of the spark plug is realized.
Of course, the present invention may have other embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present invention without departing from the spirit and the essence of the present invention, and these corresponding changes and modifications should fall within the protection scope of the appended claims.
Claims (8)
1. The constant-power control system of the parking heater spark plug is characterized by comprising a first module, a second module, a third module, a fourth module, a fifth module, a sixth module and a micro control unit;
the first module comprises a triode Q1, wherein the base of the triode Q1 is connected to the pulse width modulation control signal output by the sixth module, and the collector outputs a starting voltage to the second module;
the second module comprises an NMOS transistor Q2 and an inductor L1, wherein the grid electrode of the NMOS transistor Q2 is connected with the starting voltage, the drain electrode of the NMOS transistor Q2 is connected with an external power supply, the source electrode of the NMOS transistor Q2 is connected with one end of the inductor L1, and the other end of the inductor L1 is connected with the spark plug;
the third module comprises a resistor R5 and an amplifying circuit, wherein one end of the resistor R5 is grounded, and the other end of the resistor R5 is connected with the spark plug and is used for sampling the current of the spark plug; the amplifying circuit is used for amplifying the current of the spark plug sampled by the resistor R5 and then feeding the current back to the micro control unit;
one end of the resistor R4 of the fourth module is connected with the spark plug and is used for connecting the voltage of the spark plug, the other end of the resistor R6 is connected with the resistor R6, and the other end of the resistor R6 is grounded; one end of the resistor R4 connected with the resistor R6 is used for outputting the acquired voltage of the spark plug to the fifth module and the micro control unit;
the fifth module comprises resistors R13, R14 and R16, a capacitor C11 and an operational amplifier U1B, and the resistances of the resistor R16 and the resistor R13 are equal, wherein one end of the resistor R16 is used as a first input end of the fifth module and is used for accessing a pulse width modulation signal output by the micro control unit, and the other end of the resistor R16 is connected with a non-inverting input end of the operational amplifier U1B; one end of the resistor R13 is connected with the inverting input end of the operational amplifier U1B, and the other end of the resistor R13 is used as the second input end of the fifth module and is used for connecting the voltage output by the fourth module; the capacitor C11 and the resistor R14 are connected in series, one series end is connected with the output end of the operational amplifier U1B, and the other series end is connected with the inverting input end of the operational amplifier U1B; the output end of the operational amplifier U1B is used for outputting a control deviation signal;
the sixth module comprises an operational amplifier U1C, wherein the non-inverting input terminal of the operational amplifier U1C is used for accessing a sawtooth wave signal given by the micro control unit, the inverting input terminal is used for accessing a control deviation signal output by the fifth module, and the output terminal is used for outputting a pulse width modulation signal;
the micro control unit is used for obtaining the current power of the spark plug according to the current and the voltage, and then adjusting the duty ratio of the pulse width modulation signal output to the fifth module according to the current power and the required power.
2. The system as claimed in claim 1, wherein the first module further comprises resistors R1-R3 and a diode D1;
the base electrode of the triode Q1 is respectively connected with a resistor R1 and a resistor R2, wherein the other end of the resistor R1 is used as the input end of the first module and is connected with the pulse width modulation control signal output by the sixth module, and the other end of the resistor R2 is grounded; the emitter of the transistor Q1 is grounded, the collector is connected to the cathode of the diode D1 and the resistor R3, respectively, wherein the anode of the diode D1 is grounded, and the other end of the resistor R3 is used for outputting the turn-on voltage.
3. The system of claim 1, wherein the second module further comprises capacitors C1, C2 and a diode D2;
the source of the NMOS transistor Q2 is connected to the anode of the capacitor C1 and the cathode of the diode D2, wherein the anode of the diode D2 is grounded, the cathode of the capacitor C1 is grounded, the other end of the inductor L1 is connected to the anode of the capacitor C2, and the cathode of the capacitor C2 is grounded.
4. The constant power control system for a parking heater spark plug according to claim 1, wherein said external power source is 24V.
5. The system of claim 1, wherein the amplification circuit of the third module comprises resistors R8-R11, capacitors C3-C6, and operational amplifier U1A;
one end of the resistor R9 is connected with the spark plug and is used for connecting the current of the spark plug, the other end of the resistor R9 is connected with the non-inverting input end of the operational amplifier U1A, and meanwhile, the non-inverting input end of the operational amplifier U1A is grounded after being connected with the capacitor C4; the output end of the operational amplifier U1A is connected with one end of a resistor R11, the other end of the resistor R11 is used as the output end of a third module and is used for feeding back the current of the spark plug to the micro control unit, meanwhile, the output end of the resistor R11 is also connected with one end of a capacitor C6, and the other end of the capacitor C6 is grounded; the capacitor C5 is connected with the resistor R10 in parallel, and the two parallel ends are respectively connected with the output end and the inverting input end of the operational amplifier U1A; the capacitor C3 is connected in parallel with the resistor R8, one parallel end is connected with the inverting input end of the operational amplifier U1A, and the other parallel end is grounded.
6. The system of claim 1, wherein the fourth module further comprises a resistor R7 and capacitors C9, C10;
the ungrounded end of the resistor R6 is respectively connected with one ends of a capacitor C9 and a resistor R7, meanwhile, the other end of the capacitor C9 is grounded, and the other end of the resistor R7 is used as a first output end of the fourth module and used for feeding back the voltage of the spark plug to the micro control unit; the first output terminal of the resistor R7 is further connected to one terminal of the capacitor C10, and the other terminal of the capacitor C10 is grounded.
7. The system of claim 1, wherein the fifth module further comprises resistors R12, R15 and capacitors C7, C8;
the capacitor C8 and the resistor R15 are connected in series and then connected in parallel at two ends of the resistor R16, and one end of the capacitor C8 and one end of the resistor R15, which are not connected with the resistor R16, are grounded; the capacitor C7 is connected in parallel with the resistor R12, one of which is connected in parallel with the inverting input terminal of the operational amplifier U1B, and the other is connected in parallel with the ground.
8. The system of claim 1, wherein the sixth module comprises further resistors R17-R20;
one end of the resistor R17 is connected with the non-inverting input end of the operational amplifier U1C, and the other end of the resistor R17 is used as the first input end of the sixth module and is used for accessing a sawtooth wave signal given by the micro control unit; one end of the resistor R18 is connected to the inverting input terminal of the operational amplifier U1C, and the other end of the resistor R18 is used as the second input terminal of the sixth module and is used for accessing the control deviation signal output by the fifth module; one end of the resistor R19 is connected with the non-inverting input end of the operational amplifier U1C, and the other end is grounded; one end of the resistor R20 is connected with the inverting input end of the operational amplifier U1C, and the other end is connected with high level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920086038.3U CN209904485U (en) | 2019-01-18 | 2019-01-18 | Constant power control system of parking heater spark plug |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920086038.3U CN209904485U (en) | 2019-01-18 | 2019-01-18 | Constant power control system of parking heater spark plug |
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| Publication Number | Publication Date |
|---|---|
| CN209904485U true CN209904485U (en) | 2020-01-07 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920086038.3U Expired - Fee Related CN209904485U (en) | 2019-01-18 | 2019-01-18 | Constant power control system of parking heater spark plug |
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| Country | Link |
|---|---|
| CN (1) | CN209904485U (en) |
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2019
- 2019-01-18 CN CN201920086038.3U patent/CN209904485U/en not_active Expired - Fee Related
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