CN115047925B - Passive radiation type constant temperature control system and control method based on PID controller - Google Patents
Passive radiation type constant temperature control system and control method based on PID controller Download PDFInfo
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- CN115047925B CN115047925B CN202210187851.6A CN202210187851A CN115047925B CN 115047925 B CN115047925 B CN 115047925B CN 202210187851 A CN202210187851 A CN 202210187851A CN 115047925 B CN115047925 B CN 115047925B
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- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 48
- 239000000919 ceramic Substances 0.000 claims description 40
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
- G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
Abstract
The invention belongs to the technical field of temperature control, constant temperature and heat preservation of equipment needing temperature control under a normal temperature environment of a field foundation station, and particularly relates to a passive radiation type constant temperature control system based on a PID controller, which comprises the following components: the device comprises a temperature acquisition circuit, a heating driving circuit, a power supply circuit, a USB data acquisition card and a data processing terminal; amplifying and conditioning the weak voltage signals by the temperature acquisition circuit, acquiring the weak voltage signals in real time, and inputting the weak voltage signals to a data processing terminal through a USB data acquisition card; the data processing terminal performs voltage-temperature conversion processing on the received amplified voltage signal to obtain real temperature acquired in real time, performs closed-loop control in a PID control mode by utilizing deviation of target temperature and real temperature acquired in real time to obtain a PWM signal duty ratio value, sends the PWM signal duty ratio value to the USB data acquisition card to generate a PWM signal, inputs the PWM signal to the heating driving circuit, and performs temperature regulation and temperature constant control on equipment needing temperature control according to preset target temperature.
Description
Technical Field
The invention belongs to the technical field of temperature control, constant temperature and heat preservation of equipment needing temperature control under a normal temperature environment of a field foundation station, and particularly relates to a passive radiation type constant temperature control system and a control method based on a PID controller.
Background
The constant temperature means that the temperature of equipment needing to be controlled is kept constant by a manual or automatic control method under a certain environment, and in order to achieve the aim, the temperature change of the equipment needing to be controlled is measured in real time by a temperature sensor, and then the temperature is regulated by a heater, so that the constant temperature is always kept.
With the rapid development of science and technology and the gradual improvement of manufacturing process, various photoelectric devices and precise instruments are widely used; in the use process of the photoelectric device and the precision instrument, the requirements on the use environment are very strict, and especially the requirements on the environment temperature are higher; it is necessary to operate properly in an environment temperature where the temperature fluctuation range is extremely small or kept constant.
The temperature change can cause the change of parameters of each optical element needing to control the temperature, for example, the temperature change causes the change of refractive index of the prism, the change of the emergent angle of light rays, the change of the density of a reticle caused by the thermal expansion of the grating due to the temperature, the blue shift or the red shift of the transmission center wavelength of the interference filter due to the decrease or the increase of the temperature, and the like; the parameters of these optical elements vary with temperature and can lead to temperature drift in the end result.
When the temperature of the photoelectric device is detected manually by manpower, the environment temperature can not be detected in real time, so that the working performance and stability of the photoelectric device are reduced, and the accuracy of an output result is affected.
At present, the existing constant temperature control system has poor control precision in the aspect of temperature control, and has large volume and high cost; in addition, the existing thermostatic control circuit in the thermostatic control system has the problems of poor stability and safety, and the deviation caused by the thermal effect of an optoelectronic device, an optical element or a precise instrument is increased.
In order to reduce the deviation caused by the thermal effect of the photoelectric device, the optical element or the precision instrument as much as possible by the temperature control method for the temperature control system, it is necessary to invent a passive radiation type constant temperature control system based on a PID controller.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a passive radiation type constant temperature control system based on a PID controller, which can always keep the temperature of equipment needing to be controlled within the range of target temperature +/-0.005 ℃ set by a user in a normal temperature environment, and comprises: the device comprises a temperature acquisition circuit, a heating driving circuit, a power supply circuit, a USB data acquisition card and a data processing terminal;
The power supply circuit is respectively and electrically connected with the temperature acquisition circuit and the heating driving circuit and provides working voltage for normal operation for the temperature acquisition circuit and the heating driving circuit;
the temperature acquisition circuit and the heating driving circuit are respectively in communication connection with equipment needing temperature control and are used for carrying out temperature acquisition and temperature control on the equipment needing temperature control;
the temperature acquisition circuit, the USB data acquisition card and the heating driving circuit are sequentially connected in a communication way, and the USB data acquisition card is connected with the data processing terminal in a communication way;
Converting a resistance signal output by a temperature acquisition circuit to a negative temperature coefficient thermistor in equipment needing temperature control into a weak voltage signal, amplifying and conditioning the weak voltage signal, acquiring the weak voltage signal in real time, inputting the amplified and conditioned voltage signal to a USB data acquisition card, and inputting the amplified and conditioned voltage signal to a data processing terminal by the USB data acquisition card;
The data processing terminal carries out average value filtering on the received amplified and conditioned voltage signal to obtain a voltage signal with small fluctuation and low noise, carries out voltage-temperature conversion processing on the voltage signal to obtain real-time acquired actual temperature, utilizes deviation of target temperature and real-time acquired actual temperature, carries out closed-loop control in a PID control mode to obtain a PWM signal duty ratio value, sends the PWM signal duty ratio value to a USB data acquisition card, generates a PWM signal through the USB data acquisition card, and then inputs the PWM signal to a heating driving circuit, and the heating driving circuit carries out temperature regulation, heating temperature rise, heating control and temperature constant control on equipment needing temperature control according to the preset target temperature and the received PWM signal to ensure that the equipment needing temperature control keeps a constant temperature.
As one of the improvements of the above technical scheme, the USB data acquisition card is provided with a digital I/O pin and an a/D sampling pin, which are used for reading, receiving and forwarding the amplified voltage signal; and the heating driving circuit is also used for generating PWM signals according to the duty ratio values of the input PWM signals and sending the PWM signals to the heating driving circuit.
As one of the improvements of the above technical solutions, the temperature acquisition circuit includes: a weak current constant current source sub-circuit and a voltage signal amplifying and conditioning sub-circuit;
the weak current constant current source sub-circuit is electrically connected with the voltage signal amplifying and conditioning sub-circuit;
The weak current constant current source sub-circuit is used for providing a weak current signal flowing through a negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled in the temperature acquisition circuit, and converting a resistance signal output by the negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled into a weak voltage signal to obtain a corresponding weak voltage signal;
The voltage signal amplifying and conditioning sub-circuit is used for amplifying and conditioning the weak voltage signal to obtain an amplified and conditioned voltage signal, and inputting the amplified and conditioned voltage signal to the USB data acquisition card.
As one of the improvements of the above technical solution, the weak current constant current source sub-circuit includes: the three-terminal adjustable current source U5, the micropower voltage reference source D3, the first resistor R3 and the second resistor R4;
One end of a first resistor R3, one end of a micropower voltage reference source D3 and one end of a negative temperature coefficient thermistor RT1 are connected with a voltage signal amplification conditioning sub-circuit together, the other end of the negative temperature coefficient thermistor RT1 is connected with weak current ground AGND, one end of the first resistor R3 and one end of a second resistor R4 are connected with an adjustable pin R of a three-terminal adjustable current source U5, the other end of the second resistor R4 and the other end of the micropower voltage reference source D3 are connected with a negative polarity pin V-of the three-terminal adjustable current source U5, and a positive polarity pin V+ of the three-terminal adjustable current source U5 is connected with a power circuit +12V;
The voltage signal amplification conditioning circuit comprises: the third resistor R5, the fourth resistor R6, the fifth resistor R7, the first tantalum capacitor C3, the second tantalum capacitor C5, the first ceramic chip capacitor C4, the second ceramic chip capacitor C6, the third ceramic chip capacitor C7, the fourth ceramic chip capacitor C8 and the instrument operational amplifier U6;
One end of the third resistor R5 is connected with a weak current constant current source sub-circuit, one end of the first tantalum capacitor C3, one end of the first ceramic chip capacitor C4 and a positive polarity pin +VS of the instrument operational amplifier U6 are all connected with a power circuit +12V, one end of the second tantalum capacitor C5, one end of the second ceramic chip capacitor C6 and a negative polarity pin-VS of the instrument operational amplifier U6 are all connected with the power circuit-12V,
One end of the third ceramic capacitor C7 is respectively connected with the non-inverting input end +VIN of the instrument operational amplifier U6 and the other end of the third resistor R5, the other end of the third ceramic capacitor C7 is connected with the inverting input end-VIN of the instrument operational amplifier U6,
The two ends of the fourth resistor R6 are connected with a gain pin RG of the instrument operational amplifier U6, one end of the fifth resistor R7 and one end of the fourth ceramic capacitor C8 are connected with an A/D sampling pin of the USB data acquisition card, and the OUTPUT end OUTPUT of the instrument operational amplifier U6 is connected with the other end of the fifth resistor R7;
The other end of the first tantalum capacitor C3 and the other end of the second tantalum capacitor C5, the other end of the first ceramic chip capacitor C4, the other end of the second ceramic chip capacitor C6, the other end of the third ceramic chip capacitor C7 and the other end of the fourth ceramic chip capacitor C8 are connected with weak current ground AGND through an inverting input end-VIN and a reference voltage end REF of the instrument operational amplifier U6.
As one of the improvements of the above technical solutions, the heating driving circuit includes: the solid state relay U9, the sixth resistor R12, the N channel enhanced field effect transistor T1, the fuse F1 and the heating resistor RS1-RS4;
one end of a sixth resistor R12, a grid electrode G of an N-channel enhanced field effect transistor T1 is connected with a digital I/O pin of the USB data acquisition card, a drain electrode D of the N-channel enhanced field effect transistor T1 is connected with a negative polarity control pin of a solid state relay U9,
The other end of the sixth resistor R12 and the source electrode S of the N channel enhanced field effect transistor T1 are connected with the strong current ground PGND, the positive polarity control pin of the solid state relay U9 is connected with the power circuit +5V,
One end of a fuse T1 is connected with a negative polarity load wiring pin of the solid-state relay U9, the other end of the fuse T1 is connected with one ends of heating resistance wires RS1-RS4, the other ends of the RS1-RS4 are connected with a strong current ground PGND, and a positive polarity load wiring pin of the solid-state relay U9 is connected with a power circuit 12V;
PWM signals output by digital I/O pins of the USB data acquisition card are input to a grid G of an N-channel enhanced field effect transistor T1 in the heating driving circuit; according to the input PWM signal, the temperature of the equipment to be controlled is regulated, and the heating resistance wires RS1-RS4 are controlled to stop heating or start heating, so that the actual temperature of the equipment to be controlled is reduced or increased;
When the actual temperature is higher than the target temperature, the positive duty ratio of the PWM signal is reduced, the negative duty ratio is increased, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level is higher than the time that the grid electrode G is at a high level, the conduction time of the N-channel enhanced field effect transistor T1 is reduced or even stopped, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is short, the negative polarity control pin and the positive polarity control pin of the solid state relay U9 are connected with a power supply 5V, meanwhile, the high level is kept, the circuit loop is approximately disconnected, so that the conduction time of the negative polarity load wiring pin, the positive polarity load wiring pin and the power supply 12V of the solid state relay U9 is smaller than the disconnection time, at the moment, the heating of the heating resistance wire is weakened or even stopped, and the actual temperature is reduced;
When the actual temperature is lower than the target temperature, the positive duty ratio of the PWM signal is increased, the negative duty ratio is reduced, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a high level is higher than the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level, the conduction time of the N-channel enhanced field effect transistor T1 is increased, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is long and even on, the negative polarity control pin of the solid state relay U9 is connected with the strong current PGND and keeps at a low level, the positive polarity control pin is connected with the power supply 5V and keeps at a high level, a circuit loop is formed, the time that the negative polarity load connection pin and the positive polarity load connection pin of the solid state relay U9 are connected with the power supply 12V is increased, at the moment, the current flowing through the heating resistance wires RS1-RS4 is increased, heating is enhanced, and the actual temperature is increased.
As one of the improvements of the above technical solutions, the power supply circuit includes: the third tantalum capacitor C1, the fourth tantalum capacitor C2, the inductor L1, the 12V-to- + -12V power supply module U1, the 12V-to-5V power supply module U2, the seventh resistor R1, the eighth resistor R2, the first light emitting diode D1 and the second light emitting diode D2;
One end of the third tantalum capacitor C1 and one end of the inductor L1 are connected with the positive electrode 1 pin of the power interface JP1 and are externally connected to the positive electrode of the external 12V adapter power supply through wires,
One end of the fourth tantalum capacitor C2 and the other end of the inductor L1 are connected with the positive electrode of the first light-emitting diode D1, the positive polarity input end +vin of the 12V-to-12V power module U1 and the positive polarity input end +vin of the 12V-to-5V power module U2 are connected, the positive electrode of the first light-emitting diode D1 is connected with the positive polarity input end +vin of the 12V-to-12V power module U1, the negative electrode of the first light-emitting diode D1 is connected with one end of the seventh resistor R1,
The anode of the second light-emitting diode D2 is connected with the 5V output end of the 12V-to-5V power supply module U2;
The other end of the third tantalum capacitor C1, the other end of the fourth tantalum capacitor C2, the other end of the seventh resistor R1, the other end of the eighth resistor R2, the negative polarity input ends-Vin of the 12V-to- + -12V power supply module U1 and the 12V-to-5V power supply module U2 are connected with a strong current ground PGND;
The positive polarity output end of the 12V-to-12V power supply module U1 outputs +12V voltage, the negative polarity output end of the 12V-to-12V power supply module U1 outputs-12V voltage, and the output public end of the 12V-to-12V power supply module U1 is connected with weak current ground AGND.
As one of the improvements of the above technical solutions, the data processing terminal includes: the system comprises a signal receiving module, a voltage-temperature conversion module, a temperature deviation acquisition module, a position type PID controller and a data display and storage module;
The signal receiving module is used for receiving the amplified voltage signal sent by the USB data acquisition controller;
the voltage-temperature conversion module is used for performing voltage-temperature conversion on the amplified voltage signal to obtain an actual temperature;
Wherein T is an actual temperature value acquired in real time; u is the voltage value of the amplified voltage signal after average value filtering processing; i is the current flowing through the negative temperature coefficient thermistor; r 25 is the resistance value of the negative temperature coefficient thermistor at 25 ℃; b is the material coefficient of the negative temperature coefficient thermistor;
the temperature deviation acquisition module is used for carrying out difference on the target temperature and the actual temperature, taking the difference value of the target temperature and the actual temperature as the temperature deviation, and inputting the temperature deviation into the position type PID controller;
the position type PID controller is used for calculating to obtain the duty ratio of the PWM signal by adopting a PID control mode according to the received temperature deviation and sending the duty ratio value of the PWM signal to the USB data acquisition card;
Wherein u (k) is a control amount output by the controller; e (i) is a deviation value of the actual temperature from the target temperature at the ith calculation from the start of control; e (k) is the deviation value of the current actual temperature and the target temperature; e (k-1) is the deviation value of the last actual temperature and the target temperature; k p is a proportionality coefficient; k i is an integral coefficient; k d is a differential coefficient;
The data display and storage module is used for realizing real-time interface display of target temperature and actual temperature and storage of temperature data in the control process, so as to realize visualization of a control system.
The invention also provides a passive radiation type constant temperature control method based on the PID controller, which comprises the following steps:
the temperature acquisition circuit converts resistance signals output by two ends of a negative temperature coefficient thermistor in equipment needing temperature control into corresponding weak voltage signals, acquires the weak voltage signals in real time, amplifies and conditions the weak voltage signals, and transmits the weak voltage signals to the USB data acquisition card;
The USB data acquisition card receives the amplified and conditioned voltage signal transmitted by the temperature acquisition circuit, transmits the amplified and conditioned voltage signal to the data processing terminal through USB communication,
The data processing terminal carries out average value filtering on the received amplified and conditioned voltage signal to obtain a voltage signal with small fluctuation and low noise, carries out voltage-temperature conversion processing on the voltage signal to obtain real temperature acquired in real time, and simultaneously monitors the target temperature set by the user interface in real time;
the deviation value of the target temperature and the real temperature acquired in real time is utilized, the PID control mode is adopted to carry out closed-loop control, the PWM signal duty ratio value is obtained and sent to the USB data acquisition card, the corresponding PWM signal is generated through the USB data acquisition card and then is input to the heating driving circuit, the heating driving circuit continuously adjusts the voltage at two ends of the heating resistance wire according to the preset target temperature and the received PWM signal, the temperature of equipment needing temperature control is regulated, heated and heated, heated and controlled constantly, and meanwhile, the temperature in the equipment needing temperature control is displayed and stored in the data processing terminal in real time, so that the equipment needing temperature control keeps a constant temperature.
Compared with the prior art, the invention has the beneficial effects that:
1. The external 100W-12V power adapter is input, the power circuit can output + -12V stabilized voltage and 5V stabilized voltage, the power indicator lamp is used as a power supply for visual display, and the indicator lamp is always on when the power circuit works normally;
2. The negative temperature coefficient thermistor outputs voltage signals which can be acquired in real time by the USB data acquisition card through the temperature acquisition circuit;
3. the heating driving circuit realizes heating control and temperature adjustment of the heating resistance wire according to the PWM signal output by the USB data acquisition card;
4. The USB data acquisition card acquires a voltage signal output by the temperature acquisition circuit, generates a PWM signal according to the PWM duty ratio value calculated by the position type PID controller, and inputs the PWM signal to the heating driving circuit so as to control the heating driving circuit and the heating resistance wire, and communicates and exchanges data with the data processing terminal through a USB data wire;
5. The data processing terminal performs data storage, visual display and man-machine interaction by running a system program of a passive radiation type constant temperature control system based on a PID controller;
6. the constant temperature control system disclosed by the invention is used for assisting temperature control on equipment needing temperature control to reduce deviation and influence caused by a thermal effect, has control accuracy of +/-0.005 ℃, and has a high-accuracy heat preservation function of the equipment needing temperature control at normal temperature.
Drawings
FIG. 1 is a schematic diagram of a passive radiation type constant temperature control system based on a PID controller;
FIG. 2 is a schematic diagram of the structure of a temperature acquisition circuit of a passive radiation type constant temperature control system based on a PID controller;
FIG. 3 is a schematic diagram of the heating driving circuit of a passive radiation type constant temperature control system based on a PID controller;
FIG. 4 is a schematic diagram of the structure of a USB data acquisition card of a passive radiation type constant temperature control system based on a PID controller;
FIG. 5 is a schematic diagram of the power supply circuit of a passive radiation type constant temperature control system based on a PID controller of the present invention;
Fig. 6 is a method flow chart of a passive radiative thermostat control method based on a PID controller of the invention.
Detailed Description
The invention will now be further described with reference to the accompanying drawings.
As shown in fig. 1, the invention provides a passive radiation type constant temperature control system based on a PID controller, which is used for reducing deviation caused by thermal effects of photoelectric devices, optical elements or precise instruments by assisting temperature control to equipment needing temperature control, and adopts a PID control loop to ensure that the temperature of the shell of the equipment needing temperature control is kept within +/-0.005 ℃ to have control precision, and has a heat preservation function of the equipment needing temperature control under normal temperature environment.
The system comprises: the device comprises a temperature acquisition circuit, a heating driving circuit, a power supply circuit, a USB data acquisition card and a data processing terminal;
the power supply circuit is respectively and electrically connected with the temperature acquisition circuit and the heating driving circuit and provides working voltage for normal operation for the temperature acquisition circuit and the heating driving circuit; the temperature acquisition circuit and the heating driving circuit are respectively in communication connection with equipment needing temperature control and are used for carrying out temperature acquisition and temperature control on the equipment needing temperature control;
the temperature acquisition circuit, the USB data acquisition card and the heating driving circuit are sequentially connected in a communication way, and the USB data acquisition card is connected with the data processing terminal in a communication way;
The temperature acquisition circuit acquires a resistance signal output by a negative temperature coefficient thermistor in equipment needing temperature control in real time, and inputs the voltage signal after conversion, amplification and conditioning to the USB data acquisition card, and the USB data acquisition card inputs the acquired voltage signal to the data processing terminal;
The data processing terminal carries out average value filtering on the received amplified and conditioned voltage signal to obtain a voltage signal with small fluctuation and low noise, carries out voltage-temperature conversion processing on the voltage signal to obtain real-time acquired actual temperature, utilizes deviation of target temperature and real-time acquired actual temperature, carries out closed-loop control in a PID control mode to obtain a PWM signal duty ratio value, sends the PWM signal duty ratio value to a USB data acquisition card, generates a PWM signal through the USB data acquisition card, and then inputs the PWM signal to a heating driving circuit, and the heating driving circuit carries out temperature regulation, heating temperature rise, heating control and temperature constant control on equipment needing temperature control according to the preset target temperature and the received PWM signal to ensure that the equipment needing temperature control keeps a constant temperature.
The USB data acquisition card is provided with a digital I/O pin and an A/D sampling pin and is used for reading, receiving and forwarding the amplified voltage signals; and the device is also used for generating PWM signals according to the duty ratio of the input PWM signals and sending the PWM signals to the heating driving circuit.
As shown in fig. 2, the temperature acquisition circuit includes: a weak current constant current source sub-circuit and a voltage signal amplifying and conditioning sub-circuit;
the weak current constant current source sub-circuit is electrically connected with the voltage signal amplifying and conditioning sub-circuit;
The weak current constant current source sub-circuit is used for providing a weak current signal flowing through the negative temperature coefficient thermistor RT1 or RT2 in equipment needing temperature control in the temperature acquisition circuit, and converting the resistance value of the negative temperature coefficient thermistor RT1 or RT2 in the equipment needing temperature control into a voltage value to obtain a corresponding real-time voltage signal; the negative temperature coefficient thermistor is a temperature sensor which is positioned in equipment needing temperature control and outside the temperature acquisition circuit; the temperature sensor has the function of converting a temperature value into a resistance value, and the resistance value of the temperature sensor changes along with the change of the ambient temperature, similar to a resistor; the negative temperature coefficient thermistor is connected with the temperature acquisition circuit through an external lead.
The voltage signal amplifying and conditioning sub-circuit is used for amplifying the voltage signal to obtain an amplified voltage signal, and inputting the amplified voltage signal to the USB data acquisition card.
Specifically, the weak current constant current source sub-circuit includes: the three-terminal adjustable current source U5, the micropower voltage reference source D3, the first resistor R3 and the second resistor R4;
One end of a first resistor R3, one end of a micropower voltage reference source D3 and one end of a negative temperature coefficient thermistor RT1 are connected with a voltage signal amplification conditioning sub-circuit together, the other end of the negative temperature coefficient thermistor RT1 is connected with weak current ground AGND, one end of the first resistor R3 and one end of a second resistor R4 are connected with an adjustable pin R of a three-terminal adjustable current source U5, the other end of the second resistor R4 and the other end of the micropower voltage reference source D3 are connected with a negative polarity pin V-of the three-terminal adjustable current source U5, and a positive polarity pin V+ of the three-terminal adjustable current source U5 is connected with a power circuit +12V;
The voltage signal amplification conditioning circuit comprises: the third resistor R5, the fourth resistor R6, the fifth resistor R7, the first tantalum capacitor C3, the second tantalum capacitor C5, the first ceramic chip capacitor C4, the second ceramic chip capacitor C6, the third ceramic chip capacitor C7, the fourth ceramic chip capacitor C8 and the instrument operational amplifier U6;
One end of the third resistor R5 is connected with a weak current constant current source sub-circuit, one end of the first tantalum capacitor C3, one end of the first ceramic chip capacitor C4 and a positive polarity pin +VS of the instrument operational amplifier U6 are all connected with a power circuit +12V, one end of the second tantalum capacitor C5, one end of the second ceramic chip capacitor C6 and a negative polarity pin-VS of the instrument operational amplifier U6 are all connected with the power circuit-12V,
One end of the third ceramic capacitor C7 is respectively connected with the non-inverting input end +VIN of the instrument operational amplifier U6 and the other end of the third resistor R5, the other end of the third ceramic capacitor C7 is connected with the inverting input end-VIN of the instrument operational amplifier U6,
The two ends of the fourth resistor R6 are connected with a gain pin RG of the instrument operational amplifier U6, one end of the fifth resistor R7 and one end of the fourth ceramic capacitor C8 are connected with an A/D sampling pin of the USB data acquisition card, and the OUTPUT end OUTPUT of the instrument operational amplifier U6 is connected with the other end of the fifth resistor R7;
The other end of the first tantalum capacitor C3 and the other end of the second tantalum capacitor C5, the other end of the first ceramic chip capacitor C4, the other end of the second ceramic chip capacitor C6, the other end of the third ceramic chip capacitor C7 and the other end of the fourth ceramic chip capacitor C8 are connected with weak current ground AGND through an inverting input end-VIN and a reference voltage end REF of the instrument operational amplifier U6.
The temperature acquisition circuit provides a weak current signal flowing through the negative temperature coefficient thermistor RT1 or RT2 in the temperature acquisition circuit through a weak current constant current source sub-circuit, converts a resistance signal output by the negative temperature coefficient thermistor RT1 or RT2 in equipment needing temperature control into a weak voltage signal to obtain a corresponding real-time weak voltage signal, utilizes a voltage amplifying and conditioning circuit to condition the voltage signal to obtain an amplified and conditioned voltage signal, inputs the amplified and conditioned voltage signal into a USB data acquisition card to obtain a voltage signal of the negative temperature coefficient thermistor RT1 or RT2 at the current temperature, and the data processing terminal calculates according to a voltage-temperature conversion formula of the negative temperature coefficient thermistor and a voltage value corresponding to the negative temperature coefficient thermistor at the current temperature to obtain the real-time acquired actual temperature. The voltage-temperature conversion is calculated at the data processing terminal, and only voltage signals corresponding to the temperature are acquired in real time and are input into the data processing terminal instead of the actual temperature; the data processing terminal obtains the voltage signal and then performs voltage-temperature conversion, so as to obtain the actual temperature.
As shown in fig. 3, the heating driving circuit includes: the solid state relay U9, the sixth resistor R12, the N channel enhanced field effect transistor T1, the fuse F1 and the heating resistor RS1-RS4;
one end of the sixth resistor R12 and the grid G of the N-channel enhanced field effect transistor T1 are connected with the digital I/O pin of the USB data acquisition card, the drain D of the N-channel enhanced field effect transistor T1 is connected with the negative polarity control pin of the solid state relay U9,
The other end of the sixth resistor R12 and the source electrode S of the N channel enhanced field effect transistor T1 are connected with the strong current ground PGND, the positive polarity control pin of the solid state relay U9 is connected with the power circuit +5V,
One end of a fuse T1 is connected with a negative polarity load wiring pin of the solid-state relay U9, the other end of the fuse T1 is connected with one ends of heating resistance wires RS1-RS4, the other ends of the RS1-RS4 are connected with a strong current ground PGND, and a positive polarity load wiring pin of the solid-state relay U9 is connected with a power circuit 12V;
PWM signals output by digital I/O pins of the USB data acquisition card are input to a grid G of an N-channel enhanced field effect transistor T1 in the heating driving circuit; according to the input PWM signal, the temperature of the equipment to be controlled is regulated, and the heating degree of the heating resistance wires RS1-RS4 is controlled, so that the actual temperature of the equipment to be controlled is reduced or increased;
When the actual temperature is higher than the target temperature, the positive duty ratio of the PWM signal is reduced, the negative duty ratio is increased, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level is higher than the time that the grid electrode G is at a high level, the conduction time of the N-channel enhanced field effect transistor T1 is reduced or even stopped, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is short, the negative polarity control pin and the positive polarity control pin of the solid state relay U9 are connected with a power supply 5V, meanwhile, the high level is kept, the circuit loop is approximately disconnected, so that the conduction time of the negative polarity load wiring pin, the positive polarity load wiring pin and the power supply 12V of the solid state relay U9 is smaller than the disconnection time, at the moment, the heating resistance wire is weakened or even stopped, and the actual temperature is reduced;
When the actual temperature is lower than the target temperature, the positive duty ratio of the PWM signal is increased, the negative duty ratio is reduced, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a high level is higher than the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level, the conduction time of the N-channel enhanced field effect transistor T1 is increased, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is long and even on, the negative polarity control pin of the solid state relay U9 is connected with the strong current PGND and keeps at a low level, the positive polarity control pin is connected with the power supply 5V and keeps at a high level, a circuit loop is formed, the time that the negative polarity load connection pin and the positive polarity load connection pin of the solid state relay U9 are connected with the power supply 12V is increased, at the moment, the current flowing through the heating resistance wires RS1-RS4 is increased, heating is enhanced, and the actual temperature is increased.
The heating driving circuit is controlled by a digital I/O pin output PWM (Pulse-Width Modulation) signal of the USB data acquisition card, the duty ratio of the PWM signal is large, the switching on degree of the solid state relay U9 is large, the voltage loaded at two ends of the heating resistance wire is high, and the temperature rise and change are rapid; the PWM signal has small duty ratio, the switch of the solid-state relay U9 has small conduction degree, the voltage loaded on the two ends of the heating resistance wire is low, and the temperature rise and change are slow;
the fuse T1 is used for limiting the maximum current of the heating circuit, and when the current of the heating circuit exceeds the rated current of the fuse T1, the fuse T1 is fused, the heating circuit is cut off, and the heating work is stopped.
As shown in fig. 4, the USB data acquisition card uses M304066, M304066, which is powered by the USB and communicates with a data processing terminal (in this embodiment, a computer) with a sampling frequency greater than 50KHz, and has 16 multi-functional I/O pins, where the 16I/O pins can be configured as different Digital inputs, digital outputs, and Analog inputs, M304066 includes 2 32-bit counters and 2 timers, and can be used for pulse counting, timing, and PWM signal outputs, 2 12-bit ADC (Analog-Digital Converter, analog-Digital conversion) Analog inputs and 2 10-bit DAC (Digital-Analog Converter) Analog outputs, and the ADC Analog inputs can be configured as two modes of single-ended inputs and differential inputs; the USB data acquisition card is used for receiving and reading the voltage signal output by the temperature acquisition circuit, outputting the PWM signal to control the heating driving circuit and communicating and data exchanging with the data processing terminal through USB.
As shown in fig. 5, the power supply circuit includes: the third tantalum capacitor C1, the fourth tantalum capacitor C2, the inductor L1, the 12V-to- + -12V power supply module U1, the 12V-to-5V power supply module U2, the seventh resistor R1, the eighth resistor R2, the first light emitting diode D1 and the second light emitting diode D2;
One end of the third tantalum capacitor C1 and one end of the inductor L1 are connected with the positive electrode 1 pin of the power interface JP1 and are externally connected to the positive electrode of the external 12V adapter power supply through wires,
One end of the fourth tantalum capacitor C2 and the other end of the inductor L1 are connected with the positive electrode of the first light-emitting diode D1, the positive polarity input end +vin of the 12V-to-12V power module U1 is connected with the positive polarity input end +vin of the 12V-to-5V power module U2, the positive electrode of the first light-emitting diode D1 is connected with the positive polarity input end +vin of the 12V-to-12V power module U1, the negative electrode of the first light-emitting diode D1 is connected with one end of the seventh resistor R1,
The anode of the second light-emitting diode D2 is connected with the 5V output end of the 12V-to-5V power supply module U2;
The other end of the third tantalum capacitor C1, the other end of the fourth tantalum capacitor C2, the other end of the seventh resistor R1, the other end of the eighth resistor R2, the negative polarity input ends-Vin of the 12V-to- + -12V power supply module U1 and the 12V-to-5V power supply module U2 are connected with a strong current ground PGND;
The positive polarity output end of the 12V-to-12V power supply module U1 outputs +12V voltage, the negative polarity output end of the 12V-to-12V power supply module U1 outputs-12V voltage, and the output public end of the 12V-to-12V power supply module U1 is connected with weak current ground AGND.
In the passive radiation type constant temperature control system based on the PID controller, the strong current ground PGND and the weak current ground AGND are connected in an internal common ground mode through a USB data acquisition card.
The power supply circuit adopts a 100W-12V adapter power supply to supply power; the 12V-to-12V power module U1 outputs bipolar direct current stabilized voltage 12V to provide normal working voltage 12V of the temperature acquisition circuit; the 12V-to-5V power module U2 outputs unipolar direct current voltage stabilization 5V and provides control voltage 5V for a solid state relay in the heating driving circuit.
The power supply circuit comprises a 12V power supply indicator lamp circuit and a 5V power supply indicator lamp circuit, wherein the power supply indicator lamp circuit is a visual display circuit for normal input and output of power supply voltage, and the indicator lamp is normally on when the power supply circuit works normally.
The data processing terminal includes: the system comprises a signal receiving module, a voltage-temperature conversion module, a temperature deviation acquisition module, a data display and storage module and a position type PID controller;
The signal receiving module is used for receiving the amplified voltage signal sent by the USB data acquisition controller;
The voltage-temperature conversion module is used for performing voltage-temperature conversion on the amplified voltage signal to obtain an actual temperature; wherein the voltage-temperature value is converted into a negative temperature coefficient thermistor temperature sensor;
Wherein T is an actual temperature value acquired in real time; u is the voltage value of the amplified voltage signal after average value filtering processing; i is the current flowing through the negative temperature coefficient thermistor; r 25 is the resistance value of the negative temperature coefficient thermistor at 25 ℃; b is the material coefficient of the negative temperature coefficient thermistor;
The reading of the temperature and voltage data is to read the voltage value of the negative temperature coefficient thermistor after passing through the temperature acquisition circuit through the USB data acquisition card, the arithmetic average value filtering is to take 30 data of the voltage value to obtain an average value as the voltage value corresponding to the actual temperature, and the processing of the voltage data is to weaken noise introduced in ADC conversion sampling and make the change of the voltage data gentle.
The temperature deviation acquisition module is used for carrying out difference on the target temperature and the actual temperature, taking the difference value of the target temperature and the actual temperature as the temperature deviation, and inputting the temperature deviation into the position type PID controller; the temperature deviation calculation is obtained by subtracting the actual temperature from the target temperature, wherein the temperature deviation value is larger than zero, the actual temperature is smaller than the target temperature, the temperature deviation value is smaller than zero, and the actual temperature is larger than the target temperature.
The data display and storage module is used for realizing real-time interface display of target temperature and actual temperature and storage of temperature data in the control process, so as to realize visualization of a control system.
The position type PID controller is used for calculating to obtain the duty ratio of the PWM signal by adopting a PID control mode according to the received temperature deviation and sending the duty ratio value of the PWM signal to the USB data acquisition card;
Wherein u (k) is a control amount output by the controller; e (i) is a deviation value of the actual temperature from the target temperature at the ith calculation from the start of control; e (k) is the deviation value of the current actual temperature and the target temperature; e (k-1) is the deviation value of the last actual temperature and the target temperature; k p is a proportionality coefficient; k i is an integral coefficient; k d is the differential coefficient.
And the constant temperature control system needing temperature control is subjected to closed-loop control by adopting a position type PID algorithm. In the above formula (2), the first term is a proportional term, and the controller immediately generates a control action to change the actual temperature in a direction of reducing the deviation once the temperature deviation is generated by instantaneously reacting to the temperature deviation; the second term is an integral term, so that the temperature deviation of a control system can be eliminated, the control effect of the integral term is increased continuously as long as the temperature deviation exists in the system, and the control effect of the integral term is a constant only when the temperature deviation of the system is zero; the third term is a differential term, so that the regulation process of the controller can be quickened, and proper correction can be given in advance according to the change trend of the temperature deviation.
In this embodiment, the data processing terminal is a computer, and the computer is used for program operation, target temperature setting, actual temperature storage and visual display of a constant temperature control system of the equipment needing temperature control.
The initialization of the parameters of the USB data acquisition card controller comprises loading a dynamic link library required by the USB data acquisition card and opening the USB data acquisition card controller, wherein pin configuration of the USB data acquisition card controller comprises analog I/O and digital I/O configuration, a timer mode for enabling a digital I/O port, a counter mode for disabling the digital I/O port, a base clock frequency of the configured timer is 48MHz, a frequency division coefficient of the configured timer is 1, the timer mode is set to be a 16-bit PWM output mode, and the frequency of a final PWM signal is 732Hz.
The position PID controller parameter initialization includes proportional term coefficient setting, integral term coefficient setting and differential term coefficient setting.
In the passive radiation type constant temperature control system based on the PID controller, PWM signal output calculates PWM duty ratio value according to the position type PID controller, and PWM signal is output by the USB data acquisition card controller to be sent to the heating driving circuit to control the heating resistance wire heating temperature control system.
In a passive radiation type constant temperature control system based on a PID controller, the temperature data storage is to store real-time temperature data of a temperature control system in a computer, and automatically create a file every day to store the temperature data.
In the passive radiation type constant temperature control system based on the PID controller, the interface programming comprises program running, program exiting, target temperature setting and real-time temperature display programming.
The passive radiation type constant temperature control system based on the PID controller has the following characteristics:
1. The total control circuit adopts an adapter power supply to provide low noise and stable working voltage; the control circuit is a total control circuit integrating a temperature acquisition circuit, a heating driving circuit, a power supply circuit and a USB data acquisition card.
2. The negative temperature coefficient thermistor is used for reading the temperature data of the equipment needing temperature control, so that the sensitivity is high;
3. the USB data acquisition card is adopted for temperature reading and heating control, so that the operation is simple and the USB data acquisition card is easy to use by hands;
4. The computer control program interface is visualized, and real-time temperature data is recorded and stored and subjected to man-machine interaction;
5. the system control precision is +/-0.005 ℃, the high-precision heat preservation function of the temperature control equipment at normal temperature is realized, and the self-adaptive temperature control can be realized.
As shown in fig. 6, the present invention further provides a passive radiation type constant temperature control method based on a PID controller, which includes:
the temperature acquisition circuit converts a resistance signal output by a negative temperature coefficient thermistor in equipment needing temperature control into a weak voltage signal, performs real-time acquisition after amplifying and conditioning of the weak voltage signal, and inputs the amplified and conditioned voltage signal to the USB data acquisition card;
the USB data acquisition card receives the amplified and conditioned voltage signal transmitted by the temperature acquisition circuit, transmits the amplified and conditioned voltage signal to the data processing terminal through USB communication, and simultaneously, the USB data acquisition card generates a corresponding PWM signal according to the PWM signal duty ratio calculated by the data processing terminal and transmits the PWM signal to the heating driving circuit;
The heating driving circuit receives a PWM signal generated by the USB data acquisition card, and controls the voltage at two ends of the heating resistance wire according to the PWM signal, so as to control the temperature of the heating resistance wire in equipment needing temperature control;
The power circuit generates +/-12V voltage for normal operation of each electronic element in the temperature acquisition circuit and 5V control voltage for a solid state relay in the heating drive circuit according to 12V power voltage input by an external 12V power adapter, and provides 0-12V voltage at two ends of the heating resistance wire;
the data processing terminal performs function configuration and parameter initialization on the USB data acquisition card, and simultaneously initializes each coefficient of proportion, integral and differential in a PID algorithm;
The received amplified and conditioned voltage signals are subjected to average value filtering to obtain voltage signals with small fluctuation and low noise, and the voltage signals are subjected to voltage-temperature conversion processing to obtain real temperatures acquired in real time, and meanwhile, target temperatures set by a user interface are monitored in real time;
the deviation value of the target temperature and the real temperature acquired in real time is utilized, the PID control mode is adopted to carry out closed-loop control, the PWM signal duty ratio value is obtained and sent to the USB data acquisition card, the USB data acquisition card is used for generating PWM signals, the PWM signals are input to the heating driving circuit, the heating driving circuit continuously adjusts the voltage at two ends of the heating resistance wire according to the preset target temperature and the received PWM signals, the temperature of equipment needing temperature control is regulated, heated and heated, heated and controlled constantly, and meanwhile, the temperature in the equipment needing temperature control is displayed and stored in the data processing terminal in real time, so that the equipment needing temperature control keeps a constant temperature.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.
Claims (4)
1. A passive radiation type constant temperature control system based on a PID controller is used for controlling temperature, keeping constant temperature and preserving heat of temperature control equipment in a field foundation station normal temperature environment, and is characterized in that the system comprises: the device comprises a temperature acquisition circuit, a heating driving circuit, a power supply circuit, a USB data acquisition card and a data processing terminal;
The power supply circuit is respectively and electrically connected with the temperature acquisition circuit and the heating driving circuit and provides working voltage for normal operation for the temperature acquisition circuit and the heating driving circuit;
the temperature acquisition circuit and the heating driving circuit are respectively in communication connection with equipment needing temperature control and are used for carrying out temperature acquisition and temperature control on the equipment needing temperature control;
the temperature acquisition circuit, the USB data acquisition card and the heating driving circuit are sequentially connected in a communication way, and the USB data acquisition card is connected with the data processing terminal in a communication way;
Converting a resistance signal output by a temperature acquisition circuit to a negative temperature coefficient thermistor in equipment needing temperature control into a weak voltage signal, amplifying and conditioning the weak voltage signal, acquiring the weak voltage signal in real time, inputting the amplified and conditioned voltage signal to a USB data acquisition card, and inputting the amplified and conditioned voltage signal to a data processing terminal by the USB data acquisition card;
The data processing terminal carries out average value filtering on the received amplified and conditioned voltage signal to obtain a voltage signal with small fluctuation and low noise, carries out voltage-temperature conversion processing on the voltage signal to obtain real-time acquired actual temperature, utilizes deviation of target temperature and real-time acquired actual temperature, carries out closed-loop control in a PID control mode to obtain a PWM signal duty ratio value, sends the PWM signal duty ratio value to a USB data acquisition card, generates a PWM signal through the USB data acquisition card, and then inputs the PWM signal to a heating driving circuit, and the heating driving circuit carries out temperature regulation, heating temperature rise, heating control and temperature constant control on equipment needing temperature control according to the preset target temperature and the received PWM signal to ensure that the equipment needing temperature control keeps a constant temperature;
The power supply circuit includes: the third tantalum capacitor C1, the fourth tantalum capacitor C2, the inductor L1, the 12V-to- + -12V power supply module U1, the 12V-to-5V power supply module U2, the seventh resistor R1, the eighth resistor R2, the first light emitting diode D1 and the second light emitting diode D2;
One end of the third tantalum capacitor C1 and one end of the inductor L1 are connected with the positive electrode 1 pin of the power interface JP1 and are externally connected to the positive electrode of the external 12V adapter power supply through wires,
One end of the fourth tantalum capacitor C2 and the other end of the inductor L1 are connected with the positive electrode of the first light-emitting diode D1, the positive polarity input end +vin of the 12V-to-12V power module U1 and the positive polarity input end +vin of the 12V-to-5V power module U2 are connected, the positive electrode of the first light-emitting diode D1 is connected with the positive polarity input end +vin of the 12V-to-12V power module U1, the negative electrode of the first light-emitting diode D1 is connected with one end of the seventh resistor R1,
The anode of the second light-emitting diode D2 is connected with the 5V output end of the 12V-to-5V power supply module U2;
The other end of the third tantalum capacitor C1, the other end of the fourth tantalum capacitor C2, the other end of the seventh resistor R1, the other end of the eighth resistor R2, the negative polarity input ends-Vin of the 12V-to- + -12V power supply module U1 and the 12V-to-5V power supply module U2 are connected with a strong current ground PGND;
The positive polarity output end of the 12V-to-12V power supply module U1 outputs +12V voltage, the negative polarity output end of the 12V-to-12V power supply module U1 outputs-12V voltage, and the output public end of the 12V-to-12V power supply module U1 is connected with weak current ground AGND;
The heating driving circuit includes: the solid state relay U9, the sixth resistor R12, the N channel enhanced field effect transistor T1, the fuse F1 and the heating resistor RS1-RS4;
one end of the sixth resistor R12 and the grid G of the N-channel enhanced field effect transistor T1 are connected with the digital I/O pin of the USB data acquisition card, the drain D of the N-channel enhanced field effect transistor T1 is connected with the negative polarity control pin of the solid state relay U9,
The other end of the sixth resistor R12 and the source electrode S of the N channel enhanced field effect transistor T1 are connected with the strong current ground PGND, the positive polarity control pin of the solid state relay U9 is connected with the power circuit +5V,
One end of a fuse T1 is connected with a negative polarity load wiring pin of the solid-state relay U9, the other end of the fuse T1 is connected with one ends of heating resistance wires RS1-RS4, the other ends of the RS1-RS4 are connected with a strong current ground PGND, and a positive polarity load wiring pin of the solid-state relay U9 is connected with a power circuit 12V;
PWM signals output by digital I/O pins of the USB data acquisition card are input to a grid G of an N-channel enhanced field effect transistor T1 in the heating driving circuit; according to the input PWM signal, the temperature of the equipment to be controlled is regulated, and the heating degree of the heating resistance wires RS1-RS4 is controlled, so that the actual temperature of the equipment to be controlled is reduced or increased;
When the actual temperature is higher than the target temperature, the positive duty ratio of the PWM signal is reduced, the negative duty ratio is increased, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level is higher than the time that the grid electrode G is at a high level, the conduction time of the N-channel enhanced field effect transistor T1 is reduced or even stopped, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is short, the negative polarity control pin and the positive polarity control pin of the solid state relay U9 are connected with a power supply 5V, meanwhile, the high level is kept, the circuit loop is approximately disconnected, so that the conduction time of the negative polarity load wiring pin, the positive polarity load wiring pin and the power supply 12V of the solid state relay U9 is smaller than the disconnection time, at the moment, the heating resistance wire is weakened or even stopped, and the actual temperature is reduced;
When the actual temperature is lower than the target temperature, the positive duty ratio of the PWM signal is increased, the negative duty ratio is reduced, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a high level is higher than the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level, the conduction time of the N-channel enhanced field effect transistor T1 is increased, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is long and even on, the negative polarity control pin of the solid state relay U9 is connected with the strong current PGND and keeps at a low level, the positive polarity control pin is connected with the power supply 5V and keeps at a high level, a circuit loop is formed, so that the time that the negative polarity load connection pin and the positive polarity load connection pin of the solid state relay U9 are connected with the power supply 12V is increased, at the moment, the current flowing through the heating resistance wires RS1-RS4 is increased, heating is enhanced, and the actual temperature is increased;
The temperature acquisition circuit includes: a weak current constant current source sub-circuit and a voltage signal amplifying and conditioning sub-circuit;
the weak current constant current source sub-circuit is electrically connected with the voltage signal amplifying and conditioning sub-circuit;
The weak current constant current source sub-circuit is used for providing a weak current signal flowing through a negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled in the temperature acquisition circuit, and converting a resistance signal output by the negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled into a weak voltage signal to obtain a corresponding weak voltage signal;
The voltage signal amplifying and conditioning sub-circuit is used for amplifying and conditioning the weak voltage signal to obtain an amplified and conditioned voltage signal, and inputting the amplified and conditioned voltage signal to the USB data acquisition card;
The weak current constant current source sub-circuit comprises: the three-terminal adjustable current source U5, the micropower voltage reference source D3, the first resistor R3 and the second resistor R4;
One end of a first resistor R3, one end of a micropower voltage reference source D3 and one end of a negative temperature coefficient thermistor RT1 are connected with a voltage signal amplification conditioning sub-circuit together, the other end of the negative temperature coefficient thermistor RT1 is connected with weak current ground AGND, one end of the first resistor R3 and one end of a second resistor R4 are connected with an adjustable pin R of a three-terminal adjustable current source U5, the other end of the second resistor R4 and the other end of the micropower voltage reference source D3 are connected with a negative polarity pin V-of the three-terminal adjustable current source U5, and a positive polarity pin V+ of the three-terminal adjustable current source U5 is connected with a power circuit +12V;
The voltage signal amplification conditioning sub-circuit comprises: the third resistor R5, the fourth resistor R6, the fifth resistor R7, the first tantalum capacitor C3, the second tantalum capacitor C5, the first ceramic chip capacitor C4, the second ceramic chip capacitor C6, the third ceramic chip capacitor C7, the fourth ceramic chip capacitor C8 and the instrument operational amplifier U6;
One end of the third resistor R5 is connected with a weak current constant current source sub-circuit, one end of the first tantalum capacitor C3, one end of the first ceramic chip capacitor C4 and a positive polarity pin +VS of the instrument operational amplifier U6 are all connected with a power circuit +12V, one end of the second tantalum capacitor C5, one end of the second ceramic chip capacitor C6 and a negative polarity pin-VS of the instrument operational amplifier U6 are all connected with the power circuit-12V,
One end of the third ceramic capacitor C7 is respectively connected with the non-inverting input end +VIN of the instrument operational amplifier U6 and the other end of the third resistor R5, the other end of the third ceramic capacitor C7 is connected with the inverting input end-VIN of the instrument operational amplifier U6,
The two ends of the fourth resistor R6 are connected with a gain pin RG of the instrument operational amplifier U6, one end of the fifth resistor R7 and one end of the fourth ceramic capacitor C8 are connected with an A/D sampling pin of the USB data acquisition card, and the OUTPUT end OUTPUT of the instrument operational amplifier U6 is connected with the other end of the fifth resistor R7;
The other end of the first tantalum capacitor C3 and the other end of the second tantalum capacitor C5, the other end of the first ceramic chip capacitor C4, the other end of the second ceramic chip capacitor C6, the other end of the third ceramic chip capacitor C7 and the other end of the fourth ceramic chip capacitor C8 are connected with weak current ground AGND through an inverting input end-VIN and a reference voltage end REF of the instrument operational amplifier U6.
2. The passive radiation type constant temperature control system based on the PID controller according to claim 1, wherein a digital I/O pin and an A/D sampling pin are arranged on the USB data acquisition card and used for reading, receiving and forwarding the amplified voltage signal; and the heating driving circuit is also used for generating PWM signals according to the duty ratio values of the input PWM signals and sending the PWM signals to the heating driving circuit.
3. The passive radiation type constant temperature control system based on a PID controller according to claim 1, wherein the data processing terminal comprises: the system comprises a signal receiving module, a voltage-temperature conversion module, a temperature deviation acquisition module, a position type PID controller and a data display and storage module;
The signal receiving module is used for receiving the amplified voltage signal sent by the USB data acquisition controller;
the voltage-temperature conversion module is used for performing voltage-temperature conversion on the amplified voltage signal to obtain an actual temperature;
（1）
Wherein T is an actual temperature value acquired in real time; u is the voltage value of the amplified voltage signal after average value filtering processing; i is the current flowing through the negative temperature coefficient thermistor; The resistance value of the negative temperature coefficient thermistor at 25 ℃; b is the material coefficient of the negative temperature coefficient thermistor;
the temperature deviation acquisition module is used for carrying out difference on the target temperature and the actual temperature, taking the difference value of the target temperature and the actual temperature as the temperature deviation, and inputting the temperature deviation into the position type PID controller;
the position type PID controller is used for calculating to obtain the duty ratio of the PWM signal by adopting a PID control mode according to the received temperature deviation and sending the duty ratio value of the PWM signal to the USB data acquisition card;
（2）
Wherein, A control amount output by the controller; /(I)A deviation value between the actual temperature and the target temperature at the ith calculation from the control start; /(I)The deviation value of the actual temperature and the target temperature is the current time; /(I)The deviation value of the last actual temperature and the target temperature is obtained; /(I)Is a proportionality coefficient; /(I)Is an integral coefficient; /(I)Is a differential coefficient;
The data display and storage module is used for realizing real-time interface display of target temperature and actual temperature and storage of temperature data in the control process, so as to realize visualization of a control system.
4. A passive radiation type constant temperature control method based on PID controller is used for controlling temperature, constant temperature and preserving heat of temperature control equipment in a field foundation station normal temperature environment, and comprises the following steps:
The temperature acquisition circuit converts a resistance signal output by a negative temperature coefficient thermistor in equipment needing temperature control into a weak voltage signal, performs real-time acquisition after amplifying and conditioning of the weak voltage signal, and inputs the amplified and conditioned voltage signal to the USB data acquisition card, and the USB data acquisition card inputs the amplified and conditioned voltage signal to the data processing terminal;
The USB data acquisition card receives the amplified and conditioned voltage signal transmitted by the temperature acquisition circuit, transmits the amplified and conditioned voltage signal to the data processing terminal through USB communication,
The data processing terminal carries out average value filtering on the received amplified and conditioned voltage signal to obtain a voltage signal with small fluctuation and low noise, carries out voltage-temperature conversion processing on the voltage signal to obtain real temperature acquired in real time, and simultaneously monitors the target temperature set by the user interface in real time;
The deviation value of the target temperature and the real temperature acquired in real time is utilized, the PID control mode is adopted to carry out closed-loop control, the PWM signal duty ratio value is obtained and sent to the USB data acquisition card, the corresponding PWM signal is generated through the USB data acquisition card and then is input to the heating driving circuit, the heating driving circuit continuously adjusts the voltage at two ends of the heating resistance wire according to the preset target temperature and the received PWM signal, the temperature regulation, the heating temperature rise, the heating control and the temperature constant control are carried out on the equipment needing temperature control, and meanwhile, the temperature in the equipment needing temperature control is displayed and stored in the data processing terminal in real time, so that the equipment needing temperature control keeps a constant temperature;
The power supply circuit is respectively and electrically connected with the temperature acquisition circuit and the heating driving circuit and provides working voltage for normal operation for the temperature acquisition circuit and the heating driving circuit;
The power supply circuit includes: the third tantalum capacitor C1, the fourth tantalum capacitor C2, the inductor L1, the 12V-to- + -12V power supply module U1, the 12V-to-5V power supply module U2, the seventh resistor R1, the eighth resistor R2, the first light emitting diode D1 and the second light emitting diode D2;
One end of the third tantalum capacitor C1 and one end of the inductor L1 are connected with the positive electrode 1 pin of the power interface JP1 and are externally connected to the positive electrode of the external 12V adapter power supply through wires,
One end of the fourth tantalum capacitor C2 and the other end of the inductor L1 are connected with the positive electrode of the first light-emitting diode D1, the positive polarity input end +vin of the 12V-to-12V power module U1 and the positive polarity input end +vin of the 12V-to-5V power module U2 are connected, the positive electrode of the first light-emitting diode D1 is connected with the positive polarity input end +vin of the 12V-to-12V power module U1, the negative electrode of the first light-emitting diode D1 is connected with one end of the seventh resistor R1,
The anode of the second light-emitting diode D2 is connected with the 5V output end of the 12V-to-5V power supply module U2;
The other end of the third tantalum capacitor C1, the other end of the fourth tantalum capacitor C2, the other end of the seventh resistor R1, the other end of the eighth resistor R2, the negative polarity input ends-Vin of the 12V-to- + -12V power supply module U1 and the 12V-to-5V power supply module U2 are connected with a strong current ground PGND;
The positive polarity output end of the 12V-to-12V power supply module U1 outputs +12V voltage, the negative polarity output end of the 12V-to-12V power supply module U1 outputs-12V voltage, and the output public end of the 12V-to-12V power supply module U1 is connected with weak current ground AGND;
The heating driving circuit includes: the solid state relay U9, the sixth resistor R12, the N channel enhanced field effect transistor T1, the fuse F1 and the heating resistor RS1-RS4;
one end of the sixth resistor R12 and the grid G of the N-channel enhanced field effect transistor T1 are connected with the digital I/O pin of the USB data acquisition card, the drain D of the N-channel enhanced field effect transistor T1 is connected with the negative polarity control pin of the solid state relay U9,
The other end of the sixth resistor R12 and the source electrode S of the N channel enhanced field effect transistor T1 are connected with the strong current ground PGND, the positive polarity control pin of the solid state relay U9 is connected with the power circuit +5V,
One end of a fuse T1 is connected with a negative polarity load wiring pin of the solid-state relay U9, the other end of the fuse T1 is connected with one ends of heating resistance wires RS1-RS4, the other ends of the RS1-RS4 are connected with a strong current ground PGND, and a positive polarity load wiring pin of the solid-state relay U9 is connected with a power circuit 12V;
PWM signals output by digital I/O pins of the USB data acquisition card are input to a grid G of an N-channel enhanced field effect transistor T1 in the heating driving circuit; according to the input PWM signal, the temperature of the equipment to be controlled is regulated, and the heating degree of the heating resistance wires RS1-RS4 is controlled, so that the actual temperature of the equipment to be controlled is reduced or increased;
When the actual temperature is higher than the target temperature, the positive duty ratio of the PWM signal is reduced, the negative duty ratio is increased, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level is higher than the time that the grid electrode G is at a high level, the conduction time of the N-channel enhanced field effect transistor T1 is reduced or even stopped, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is short, the negative polarity control pin and the positive polarity control pin of the solid state relay U9 are connected with a power supply 5V, meanwhile, the high level is kept, the circuit loop is approximately disconnected, so that the conduction time of the negative polarity load wiring pin, the positive polarity load wiring pin and the power supply 12V of the solid state relay U9 is smaller than the disconnection time, at the moment, the heating resistance wire is weakened or even stopped, and the actual temperature is reduced;
When the actual temperature is lower than the target temperature, the positive duty ratio of the PWM signal is increased, the negative duty ratio is reduced, the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a high level is higher than the time that the grid electrode G of the N-channel enhanced field effect transistor T1 is at a low level, the conduction time of the N-channel enhanced field effect transistor T1 is increased, the conduction time of the source electrode S and the drain electrode D of the N-channel enhanced field effect transistor T1 is long and even on, the negative polarity control pin of the solid state relay U9 is connected with the strong current PGND and keeps at a low level, the positive polarity control pin is connected with the power supply 5V and keeps at a high level, a circuit loop is formed, so that the time that the negative polarity load connection pin and the positive polarity load connection pin of the solid state relay U9 are connected with the power supply 12V is increased, at the moment, the current flowing through the heating resistance wires RS1-RS4 is increased, heating is enhanced, and the actual temperature is increased;
The temperature acquisition circuit includes: a weak current constant current source sub-circuit and a voltage signal amplifying and conditioning sub-circuit;
the weak current constant current source sub-circuit is electrically connected with the voltage signal amplifying and conditioning sub-circuit;
The weak current constant current source sub-circuit is used for providing a weak current signal flowing through a negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled in the temperature acquisition circuit, and converting a resistance signal output by the negative temperature coefficient thermistor RT1 or RT2 in the equipment to be temperature controlled into a weak voltage signal to obtain a corresponding weak voltage signal;
The voltage signal amplifying and conditioning sub-circuit is used for amplifying and conditioning the weak voltage signal to obtain an amplified and conditioned voltage signal, and inputting the amplified and conditioned voltage signal to the USB data acquisition card;
The weak current constant current source sub-circuit comprises: the three-terminal adjustable current source U5, the micropower voltage reference source D3, the first resistor R3 and the second resistor R4;
One end of a first resistor R3, one end of a micropower voltage reference source D3 and one end of a negative temperature coefficient thermistor RT1 are connected with a voltage signal amplification conditioning sub-circuit together, the other end of the negative temperature coefficient thermistor RT1 is connected with weak current ground AGND, one end of the first resistor R3 and one end of a second resistor R4 are connected with an adjustable pin R of a three-terminal adjustable current source U5, the other end of the second resistor R4 and the other end of the micropower voltage reference source D3 are connected with a negative polarity pin V-of the three-terminal adjustable current source U5, and a positive polarity pin V+ of the three-terminal adjustable current source U5 is connected with a power circuit +12V;
The voltage signal amplification conditioning sub-circuit comprises: the third resistor R5, the fourth resistor R6, the fifth resistor R7, the first tantalum capacitor C3, the second tantalum capacitor C5, the first ceramic chip capacitor C4, the second ceramic chip capacitor C6, the third ceramic chip capacitor C7, the fourth ceramic chip capacitor C8 and the instrument operational amplifier U6;
One end of the third resistor R5 is connected with a weak current constant current source sub-circuit, one end of the first tantalum capacitor C3, one end of the first ceramic chip capacitor C4 and a positive polarity pin +VS of the instrument operational amplifier U6 are all connected with a power circuit +12V, one end of the second tantalum capacitor C5, one end of the second ceramic chip capacitor C6 and a negative polarity pin-VS of the instrument operational amplifier U6 are all connected with the power circuit-12V,
One end of the third ceramic capacitor C7 is respectively connected with the non-inverting input end +VIN of the instrument operational amplifier U6 and the other end of the third resistor R5, the other end of the third ceramic capacitor C7 is connected with the inverting input end-VIN of the instrument operational amplifier U6,
The two ends of the fourth resistor R6 are connected with a gain pin RG of the instrument operational amplifier U6, one end of the fifth resistor R7 and one end of the fourth ceramic capacitor C8 are connected with an A/D sampling pin of the USB data acquisition card, and the OUTPUT end OUTPUT of the instrument operational amplifier U6 is connected with the other end of the fifth resistor R7;
The other end of the first tantalum capacitor C3 and the other end of the second tantalum capacitor C5, the other end of the first ceramic chip capacitor C4, the other end of the second ceramic chip capacitor C6, the other end of the third ceramic chip capacitor C7 and the other end of the fourth ceramic chip capacitor C8 are connected with weak current ground AGND through an inverting input end-VIN and a reference voltage end REF of the instrument operational amplifier U6.
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| CN116647946B (en) * | 2023-07-27 | 2023-10-13 | 济宁九德半导体科技有限公司 | Semiconductor-based heating control system and method thereof |
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