CN215297995U - Portable non-methane total hydrocarbon analyzer high-precision EPC control system - Google Patents
Portable non-methane total hydrocarbon analyzer high-precision EPC control system Download PDFInfo
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- CN215297995U CN215297995U CN202122096075.2U CN202122096075U CN215297995U CN 215297995 U CN215297995 U CN 215297995U CN 202122096075 U CN202122096075 U CN 202122096075U CN 215297995 U CN215297995 U CN 215297995U
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Abstract
The utility model relates to a gas flow control, concretely relates to portable non-methane total hydrocarbon analyzer high accuracy EPC control system, including controller, pressure sensor, pressure detection circuit, constant current drive circuit and proportional valve, the pressure detection circuit is connected between pressure sensor and controller, receives pressure sensor's detected signal to carry out pressure feedback to the controller; the constant-current driving circuit is connected between the controller and the proportional valve, receives the PWM control waveform of the controller and controls the pressure through the proportional valve; the controller receives a feedback signal of the pressure detection circuit, performs AD conversion, and generates a PWM control waveform with a corresponding duty ratio according to a digital signal; the utility model provides a technical scheme can effectively overcome the circuit that prior art exists and realize complicacy, the lower defect of control accuracy.
Description
Technical Field
The utility model relates to a gas flow control, concretely relates to portable non-methane total hydrocarbon analyzer high accuracy EPC control system.
Background
Nowadays, along with the rapid development of economy, the energy consumption is increasing day by day, thereby causing the environmental pollution to be gradually increased. The main component of environmental pollutants is VOCs (volatile organic compounds), which are not only important causes of haze, but also induce various diseases in human beings. Therefore, emission regulation and pollution tracing of VOCs become more and more important.
At present, most VOCs analyzers are relatively large in size and heavy, collected samples need to be transported to a laboratory to be measured and analyzed, and the method is large in measurement error and incapable of achieving real-time monitoring. Although some portable products exist at present, the portable products cannot be truly portable due to the fact that the installation mode of the analysis piece and the air channel is fixed.
In portable VOCs analysis appearance, need effectively regulate and control gas flow, and the control to gas flow among the prior art mainly adopts: automatic analog quantity regulation control; pulse Width Modulation (PWM). The existing analog quantity regulation control mode generally comprises a digital-to-analog conversion circuit, a current driving circuit, a current detection circuit, a protection circuit and the like, and the method has more involved electronic components and is complex to realize.
In the existing pulse width modulation mode, firstly, a PWM control signal is converted into a voltage signal through a low-pass filter circuit, the voltage signal is linearly amplified through an operational amplifier circuit, then the voltage signal is compared and amplified with a feedback voltage of a proportional valve current through a comparison circuit, and the conduction or cut-off of an adjusting tube is controlled through an adjusting control circuit, so that the current output of a loop formed by a freewheeling diode and a proportional valve coil is controlled.
SUMMERY OF THE UTILITY MODEL
Technical problem to be solved
To the above-mentioned shortcoming that prior art exists, the utility model provides a high accuracy EPC control system of portable non-methane total hydrocarbon analysis appearance can effectively overcome the circuit that prior art exists and realize complicacy, the lower defect of control accuracy.
(II) technical scheme
In order to achieve the above purpose, the utility model discloses a following technical scheme realizes:
a portable high-precision EPC control system of a non-methane total hydrocarbon analyzer comprises a controller, a pressure sensor, a pressure detection circuit, a constant-current driving circuit and a proportional valve;
the pressure detection circuit is connected between the pressure sensor and the controller, receives a detection signal of the pressure sensor and feeds back pressure to the controller;
the constant-current driving circuit is connected between the controller and the proportional valve, receives the PWM control waveform of the controller and controls the pressure through the proportional valve;
and the controller receives the feedback signal of the pressure detection circuit, performs AD conversion, and generates a PWM control waveform with a corresponding duty ratio according to the digital signal.
Preferably, the pressure detection circuit comprises a voltage division circuit, a voltage follower circuit and a filter circuit;
the voltage division circuit receives a detection signal of the pressure sensor and performs voltage division processing;
the voltage follower circuit is connected between the voltage division circuit and the filter circuit and used for reducing the impedance of the voltage division signal reaching the AD conversion module in the controller;
and the filter circuit receives the output signal of the voltage follower circuit and performs filtering processing.
Preferably, the voltage dividing circuit comprises a voltage dividing resistor chip U3 and an external terminal J10, the pressure sensor is connected with the external terminal J10, a TVS tube D32 is connected between the external terminal J10 and the voltage dividing resistor chip U3, and the output end of the voltage dividing resistor chip U3 is connected with the voltage follower circuit.
Preferably, the voltage follower circuit comprises an operational amplifier U18, an output end of the voltage dividing resistor chip U3 is connected with a non-inverting input end of an operational amplifier U18, an output end of the operational amplifier U18 is connected with an inverting input end of an operational amplifier U18, and an output end of the operational amplifier U18 is connected with an internal AD conversion module of the controller through a filter circuit.
Preferably, the filter circuit comprises an RC filter circuit, and the RC filter circuit is composed of a resistor R44 and a capacitor C4.
Preferably, the constant current driving circuit comprises a signal isolation circuit and a signal modulation circuit;
the signal isolation circuit is connected between the controller and the signal modulation circuit and is used for isolating the influence of the output signal of the signal modulation circuit on the pressure detection circuit;
and the signal modulation circuit is connected between the signal isolation circuit and the proportional valve and used for generating PWM control waveforms with different duty ratios according to the controller and outputting driving currents with different sizes to the proportional valve.
Preferably, the signal isolation circuit comprises an isolation optocoupler U46, an input end of the isolation optocoupler U46 receives a PWM control waveform of the controller through a current limiting resistor R106, and an output end of the isolation optocoupler U46 is connected with the signal modulation circuit.
Preferably, the signal modulation circuit comprises a constant current driving chip U2 and an external terminal J14, the output end of the constant current driving chip U2 is connected with the external terminal J14 through a current-limiting resistor R50, and the external terminal J14 is connected with the proportional valve.
Preferably, a power input end of the constant current driving chip U2 is connected with a filter capacitor C6 and a diode D1, a cathode of the diode D1 is connected with a power input end of the constant current driving chip U2, and the external terminal J14 is connected with an anode of the diode D1.
(III) advantageous effects
Compared with the prior art, the utility model provides a portable non-methane total hydrocarbon analyzer high accuracy EPC control system, the control method of the analog-to-digital conversion function and the proportional valve that the integrated controller contains adopts the inside resource of controller, simplifies outside proportional valve control circuit, has the effect that realizes simply, controls stably; the constant current driving circuit can directly receive the PWM control waveform of the controller and output corresponding driving current in a linear relation to the proportional valve according to different duty ratios of the PWM control waveform, so that the gas flow is accurately controlled.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic diagram of the hardware connection relationship of the present invention;
fig. 2 is a schematic diagram of a pressure detection circuit according to the present invention;
fig. 3 is a schematic diagram of a constant current driving circuit according to the present invention;
fig. 4 is a schematic diagram of the linear relationship between the input PWM control waveform and the output driving current of the medium constant current driving circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the drawings in the embodiments of the present invention are combined below to clearly and completely describe the technical solutions in the embodiments of the present invention. It is to be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
A portable non-methane total hydrocarbon analyzer high-precision EPC control system is shown in figures 1 to 3 and comprises a controller, a pressure sensor, a pressure detection circuit, a constant-current driving circuit and a proportional valve;
the pressure detection circuit is connected between the pressure sensor and the controller, receives a detection signal of the pressure sensor and feeds back pressure to the controller;
the constant-current driving circuit is connected between the controller and the proportional valve, receives the PWM control waveform of the controller and controls the pressure through the proportional valve;
and the controller receives the feedback signal of the pressure detection circuit, performs AD conversion, and generates a PWM control waveform with a corresponding duty ratio according to the digital signal.
As shown in fig. 2, the pressure detection circuit includes a voltage dividing circuit, a voltage follower circuit, and a filter circuit;
the voltage division circuit receives a detection signal of the pressure sensor and performs voltage division processing;
the voltage follower circuit is connected between the voltage division circuit and the filter circuit and used for reducing the impedance of the voltage division signal reaching the AD conversion module in the controller;
and the filter circuit receives the output signal of the voltage follower circuit and performs filtering processing.
The bleeder circuit includes divider resistance chip U3 and external terminal J10, and external terminal J10 is connected to pressure sensor, connects TVS pipe D32 between external terminal J10 and the divider resistance chip U3, and voltage follower circuit is connected to divider resistance chip U3's output. The TVS tube D32 can prevent voltage overshoot caused by plugging and unplugging of the J10, and the pressure sensor can select 40PC100G 3A.
The voltage follower circuit comprises an operational amplifier U18, the output end of a voltage dividing resistor chip U3 is connected with the non-inverting input end of an operational amplifier U18, the output end of the operational amplifier U18 is connected with the inverting input end of an operational amplifier U18, and the output end of the operational amplifier U18 is connected with an AD conversion module in the controller through a filter circuit.
The divider resistance chip U3 selects a three-terminal voltage divider produced by MAXIM company, and the inside is a precise resistance network, and can adapt to different voltage dividing schemes through type selection, and the temperature drift is small, and the precision is high. The output signal of pressure sensor inputs operational amplifier U18 after divider resistance chip U3 partial pressure, and operational amplifier U18 is a precision fortune and puts, constitutes following circuit in the system, reduces the impedance that the signal reachd the inside AD conversion module of controller, improves the driving force, reduces system's noise, effectively promotes AD conversion module's detection precision.
The filter circuit comprises an RC filter circuit, and the RC filter circuit is composed of a resistor R44 and a capacitor C4. The filter circuit formed by the resistor R44 and the capacitor C4 enables signals to reach the AD conversion module more stably, and signal disturbance is further reduced.
As shown in fig. 3, the constant current driving circuit includes a signal isolation circuit and a signal modulation circuit;
the signal isolation circuit is connected between the controller and the signal modulation circuit and is used for isolating the influence of the output signal of the signal modulation circuit on the pressure detection circuit;
and the signal modulation circuit is connected between the signal isolation circuit and the proportional valve and used for generating PWM control waveforms with different duty ratios according to the controller and outputting driving currents with different sizes to the proportional valve.
The signal isolation circuit comprises an isolation optocoupler U46, the input end of an isolation optocoupler U46 receives the PWM control waveform of the controller through a current limiting resistor R106, and the output end of an isolation optocoupler U46 is connected with the signal modulation circuit. The isolation optocoupler U46 can effectively isolate the influence of the output signal of the signal modulation circuit on the pressure detection circuit, and reliably eliminates the problem of jumping point interference in the pressure detection circuit.
The signal modulation circuit comprises a constant current driving chip U2 and an external terminal J14, the output end of the constant current driving chip U2 is connected with the external terminal J14 through a current-limiting resistor R50, and the external terminal J14 is connected with the proportional valve.
The maximum current of the constant current driving chip U2 can reach 1A, and is limited by the current limiting resistor R50, and at this time, the current flowing through the external terminal J14 and the diode D1 is I equal to 0.1/Isense. As shown in fig. 4, the constant current driver chip U2 integrates the PWM control signal modulation and filtering function, so that when PWM control waveforms with different duty ratios are input to the ADJ terminal, driving currents with different magnitudes can be output correspondingly, and the constant current driver chip U2 has good linearity, low price and stable output.
The power input end of the constant current driving chip U2 is connected with a filter capacitor C6 and a diode D1, the cathode of the diode D1 is connected with the power input end of the constant current driving chip U2, and the external terminal J14 is connected with the anode of the diode D1. The filter capacitor C6 can stabilize the input voltage of the constant current driving chip U2, and the diode D1 can prevent the voltage from reversely flowing.
According to the technical scheme, 32 of an ST company is selected as a single chip microcomputer STM32F407 in closed-loop regulation, and multi-path ADC and timer resources are integrated inside the single chip microcomputer STM32F407, so that closed-loop control of multi-path proportional valves can be completed simultaneously.
It should be noted that the technical solution of the present application is only for providing a hardware configuration different from the prior art, so that the skilled person can implement further development under such a hardware configuration, and the software program can be programmed by the programmer in the field at a later stage according to the actual effect requirement.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.
Claims (9)
1. A high accuracy EPC control system of portable non-methane total hydrocarbon analyzer is characterized in that: the device comprises a controller, a pressure sensor, a pressure detection circuit, a constant-current driving circuit and a proportional valve;
the pressure detection circuit is connected between the pressure sensor and the controller, receives a detection signal of the pressure sensor and feeds back pressure to the controller;
the constant-current driving circuit is connected between the controller and the proportional valve, receives the PWM control waveform of the controller and controls the pressure through the proportional valve;
and the controller receives the feedback signal of the pressure detection circuit, performs AD conversion, and generates a PWM control waveform with a corresponding duty ratio according to the digital signal.
2. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 1 wherein: the pressure detection circuit comprises a voltage division circuit, a voltage following circuit and a filter circuit;
the voltage division circuit receives a detection signal of the pressure sensor and performs voltage division processing;
the voltage follower circuit is connected between the voltage division circuit and the filter circuit and used for reducing the impedance of the voltage division signal reaching the AD conversion module in the controller;
and the filter circuit receives the output signal of the voltage follower circuit and performs filtering processing.
3. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 2 wherein: the bleeder circuit includes divider resistance chip U3 and external terminal J10, pressure sensor connects external terminal J10, connect TVS pipe D32 between external terminal J10 and the divider resistance chip U3, voltage follower circuit is connected to divider resistance chip U3's output.
4. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 3 wherein: the voltage follower circuit comprises an operational amplifier U18, the non inverting input end of an operational amplifier U18 is connected to the output end of the voltage dividing resistor chip U3, the inverting input end of an operational amplifier U18 is connected to the output end of the operational amplifier U18, and the output end of the operational amplifier U18 is connected with the AD conversion module in the controller through a filter circuit.
5. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 4 wherein: the filter circuit comprises an RC filter circuit, and the RC filter circuit is composed of a resistor R44 and a capacitor C4.
6. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 1 wherein: the constant current driving circuit comprises a signal isolation circuit and a signal modulation circuit;
the signal isolation circuit is connected between the controller and the signal modulation circuit and is used for isolating the influence of the output signal of the signal modulation circuit on the pressure detection circuit;
and the signal modulation circuit is connected between the signal isolation circuit and the proportional valve and used for generating PWM control waveforms with different duty ratios according to the controller and outputting driving currents with different sizes to the proportional valve.
7. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 6 wherein: the signal isolation circuit comprises an isolation optocoupler U46, the input end of the isolation optocoupler U46 receives the PWM control waveform of the controller through a current limiting resistor R106, and the output end of the isolation optocoupler U46 is connected with the signal modulation circuit.
8. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 7 wherein: the signal modulation circuit comprises a constant current driving chip U2 and an external terminal J14, the output end of the constant current driving chip U2 is connected with the external terminal J14 through a current-limiting resistor R50, and the external terminal J14 is connected with a proportional valve.
9. The portable non-methane total hydrocarbon analyzer high accuracy EPC control system of claim 8 wherein: the power supply input end of the constant current driving chip U2 is connected with a filter capacitor C6 and a diode D1, the cathode of the diode D1 is connected with the power supply input end of the constant current driving chip U2, and the external terminal J14 is connected with the anode of the diode D1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122096075.2U CN215297995U (en) | 2021-09-01 | 2021-09-01 | Portable non-methane total hydrocarbon analyzer high-precision EPC control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122096075.2U CN215297995U (en) | 2021-09-01 | 2021-09-01 | Portable non-methane total hydrocarbon analyzer high-precision EPC control system |
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| CN215297995U true CN215297995U (en) | 2021-12-24 |
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| CN202122096075.2U Active CN215297995U (en) | 2021-09-01 | 2021-09-01 | Portable non-methane total hydrocarbon analyzer high-precision EPC control system |
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