Microcontroller-based small domestic gas boiler
Control System
The Zhu Huanli a Liu Yubin Wang Dianlong 2
(1. Yellow River Conservancy Technical Institute, Kaifeng,
Henan 475003; 2. Dalian University of Technology, Dalian,
Liaoning 116024)
CLC number: TP29 Document code: B
Abstract: In this paper, the characteristics of the small
domestic gas boilers, developed a small home based on the
MCS-51
With gas-fired boilers intelligent controller. To improve the
control of home heating, heating economy, improve people's
lives
Facilities.
Keywords: gas-fired boilers; microcontroller; controller; fuzzy
control
Development of Control System for The Minor the Gas-Fired
Boiler based Single-Chip
Microcomputer
ZHU Huan-li1 LIU Yu-Bing1 WANG Dian-Long2
(1.Yellow river conservancy technical institute Kaifeng 475003
Henan
China; 2.Dalian University of Technology Dalian 116024
Liaoning China)
Abstract: this paper develops a single-chip microcomputer
intelligence controller for the
minor gas-fired boiler which is domestic heating equipment on
the basis of investigation of
heating demand widely. The research goals are to to improve
the control quomodo of domestic
heating, to increase economics of heating, to ameliorate living
service facilities of people.
Key Words: Gas-Fired Boiler; the Single-Chip Microcomputer;
controller; Fuzzy-Control
0 Preface
At present, China's urban residents in residential heating most
of central heating in this way principle, high thermal efficiency,
Energy can be fully utilized, higher economy. But central
heating, mostly coal-fired boilers will be a great deal of ring
Environmental pollution problems. In recent years, gas-fired
boilers to natural gas as fuel efficiency, environmental pollution
and even non-polluting characteristics,
Was so highly favored people. Domestic gas boilers on the
market today are mostly imported or joint production, the price
at every turn in the million
Above, is not conducive to promoting the use of. Research and
development of safe, reliable, low-cost, intelligent small
domestic gas boiler has
Some practical significance.
(1) the system works
The boiler control system works shown in Figure 1. Water
heated by the circulating pump to force into the radiator by the
cooling
To cool, then flow back into the boiler by the pipe. Radiator part
can be seen as the load of the boiler system, water supply
before the circulating pump
Mouth outflow of hot water to flow back into the boiler through
the loop is already cooling water. Since the force generated by
the pump can be large,
Heating range can be extended to more than one use. At the
same time, the system can also provide hot water, water loss
by complement
Outlet automatically join. The temperature sensor output signal
conditioning circuit processing as the input signal of the
microcontroller system. The Department
System
to
sample
the
two-loop
temperature:
water
temperature and room temperature.
The control system of the control signal into the gas burner
control through solid state relays, three intake valve control.
Burn
The role of the burner: solid state relay is connected to the
boiler of the power burner, burner, through its internal
photoelectric detection tube detection
With or without the fire, if fire, said the firing was successful,
without turning on the ignition transformer, or start the ignition
transformer for ignition,
At the same time inlet solenoid valve is opened, when the
photoelectric cell detected flame, turn off the ignition
transformer, the system is successful ignition.
The control system according to the temperature sensor
detects the control signal is given by the control algorithm to
adjust the feed rate
Small, to adjust the size of the boiler fire, and to adjust the
boiler water temperature, thus completing the regulation of
room temperature.
Figure 1 boiler system works
2 system's hardware design
2.1 System performance requirements and characteristics
The design of control systems for domestic gas boiler
temperature control, temperature control range is 0 to 100 ° C.
The Department of
System to be able to display the time set and actual
temperature, set time cycle run, the control of the actual
temperature and
Set temperature error of less than ± 1 ° C. Due to the use of
the
product
in
different
environments
and
security
requirements,
System must have high reliability, strong anti-jamming
capability, the selected device is universal and versatile, that is,
when there is
Failure in the market can easily find, or find an alternative
product. The system to leave room for expansion, to facilitate
the successful
Can be expanded and upgraded.
The design of the system is safe, reliable, have a good
anti-jamming capability; with a strong concept of humanity,
man-machine interface is simple,
User-friendly; circuit elements with versatility and universality,
easy maintenance; system has some room for expansion.
2.2 single-chip models
Through investigation and analysis, I think that is widely used,
reliable and inexpensive MCS-51 series microcontroller
Department
The preferred device of the system to meet the system
requirements.
MCS-51 series MCU has three basic products: 8051,8751, and
8031.8751, as development and testing of general or
Mass production, taking into account the products of mass
production, as well as the device can be replaced, scalability,
and economy, the system
Not in use; 8051 internally with 4K bytes of mask ROM,
programs, once written to, can not be modified, the upgrade of
the product
Can not be achieved, and the 8031 external expansion 8K
program memory EPROM is a good program for this system,
so
The finalization of the core devices of the 8031-based control
system.
2.3 signal acquisition, conversion, and input circuit
2.3.1 Temperature sensor selection and adjustment
In order to measure the indoor temperature and the boiler
water temperature, in order to achieve satisfactory control
performance, system design sampling two loops
Temperature: Water temperature and room temperature.
Therefore, a temperature sensor in the water supply port and
interior configuration. This system has been thermometry
Is approximately between 0 ° C to 100 ° C, the integrated
temperature sensor AD590 to be able to meet the
requirements. AD590
The supply voltage conversion circuit and to enlarge the
correction circuit shown in Figure 2.
Water level control
Into the water
Controller
Temperature of the water
Temperature of the sensor
Follow
Ring
Water
Pump
Scattered
Heat
Device
Throttle valve
Out of water
Burner
Temperature of the sensor
Throttle valve
Throttle valve
Gas
Room temperature
Figure 2 AD590 input circuit
LM250 to provide precision voltage source to the AD590 two
correction circuit voltage regulator circuit, providing +2.5 V to
measure
Correction circuit. The rest is the AD590 measurement
correction circuit. The circuit parameters are calculated as
follows:
Set when the measured temperature of 0 ° C and UO = 0V; the
measured temperature of 100 ° C and UO = 5V. According to
the circuit theory, computing
Amplifier LF355 2 foot "virtual", so:
I2 = I0 is + I1, and UO = I1 · (W3 + R3)
When the temperature is 0 ℃ I2 = 273.15μA, but also of UO =
0V, then:
I1 = 0, I0 = 273.15μA, another R2, W2, the voltage across a
2.5V
R2 + W2 = 2.5V ÷ 273.15μA = 9.15KΩ
R2 = 9KΩ, W2 = 400Ω. From the above analysis shows that
regulate these two resistors can be adjusted to zero of the
temperature measurement.
Temperature of 100 ° C and UO = 5V,
12 = 273.15μA +100 μA = 373.15μA, ie I0 is +11 = 373.15μA
The constant point of reference voltage
I0 = 273.15μA therefore I1 = 100μA
W3 + R3 = 5V ÷ 100μA = 50KΩ
R3 = 47KΩ, W3 = 5KΩ. Adjust the two resistors can be
adjusted to measure the full scale.
Take R4 = (R2 + W2) / / (R3 + W3) = 9.1KΩ
Adjust, first make the AD590 in the ice water mixture, the
temperature to 0 ° C, adjust P2 so that of UO = 0V; then AD590
set
Boiling water under normal temperature and pressure, the
temperature of 100 ° C environment, adjust the W3, of UO =
5V can be.
2.3.2 the A / D conversion and its interface with 8031
A / D converter with 8-way strobe input of the ADC0809.
ADC0809 output tri-state latch, which itself can
As with a parallel I / O interface A / D converter, 8-bit data
output pin can be directly connected to the data bus.
START (start pulse input line) and ALE together, and indirectly
connected with WR can make 0809 in the choice of open
channel
Open conversion, as long as the implementation of a write to
0809 signal to start the conversion. P2.7 by inverting after
control of the two NOR gates open
No, P2.7 0:00, the two NOR gates are locked, ADC 0809 can
not work; P2.7 1, in the corresponding read and write
command
Able to work. End of conversion signal EOC gave P2.0 used to
query. Usually the EOC output is high, rising in the START
signal
Along after 0 to 8 per clock cycle goes low, after the end of the
A / D conversion, the EOC becomes high. The ADC0809
Three address lines-address lines A0, A1, A2, 8 to choose an
input channel, the systems use only two of them, the rest set
aside for system expansion
Fair use.
Indoor temperature signal address is: 1000000000000000,
8000H
The
address
of
the
outlet
1000000000000001, ie, 8001H.
R3
9.1K
R2
Of R1 9K 47K the W3
5K
W2
400
3
2
A
48
A
LF355
+5 V
-12V
AD590
+5 V
LM250
2.5V
U
temperature
signal
is:
o
+
I1
I0
I2
Due to temperature change is relatively slow, the system do
not need to set the sample and hold circuit, the A / D converter
ADC0809 directly
UO conversion of the AD590's output can be, but usually for
the fast changes of pressure and flow signals, the direct
conversion will bring greater
The error in the ADC0809 front plus a sample and hold circuit.
The design of the 2.4 output channels
AC solid state relay output channels, control actuator power off,
and then adjust the executive body switch
Intake valve. The solid state relay is a new non-contact
electronic switch, only a small input current, and TTL
Well compatible with CMOS, and circuit and the output
transistor drive non-contact switch, quite suitable for computer
monitoring system
Actuator, which will gradually replace traditional relay and SCR.
An internal optical isolation devices to prevent electromagnetic
Interference or frequency voltage output channels playing to
the monitoring and control system. The solid state relay and
microcontroller interface is relatively simple, as long as the
Microcontroller output port connected to a drive.
(3) control strategy
The control strategy is a core part of the controller. For a
control system to choose the control strategy is essential.
Fuzzy control (Fuzzy Control) is a rule-based control. It directly
using the language of control rules, the starting point is
Site operator control experience or expert knowledge in the
design need to create a precise mathematical model of the
charged object
Type, thus making the control mechanism and strategies easily
accepted and understood, designed to be simple and easy to
use. Robust fuzzy control system
Strong disturbances and parameter changes on the control
effect is greatly reduced, especially suitable for nonlinear,
time-varying and time delay system
The control of the system.
By the multi-program, the system will eventually determine the
use of two-dimensional fuzzy controller (Figure 4). Output of
the controller's use of expansion
Exhibition 8155 PB mouth high four three-pin PB4 PB5 through,
PB6 control of three solid state relays, and then relay the main
Loop control three burners of the intake valve to control the
number of burners, to control the boiler heating. All closed
Boiler standby, stop heating, open an intake valve, a burner,
boiler heating, weak firepower, open two
Intake valve, two burners, boiler heating, fire, three intake
valve is fully open, three burners at the same time work
For when the fire, in order to control the water temperature in
order to achieve the purpose of regulating the indoor
temperature. The control process is no need for D / A converter
This greatly simplifies the controller design.
Figure 3-dimensional fuzzy controller
System software design
On a single chip control system software, the monitoring
program is the most important part. System monitoring
program is to control the single
Chip system running the scheduled operation procedures. It
completes him an opportunity, then, and a variety of job
scheduling function, so that the system operating
By intent or remote command to complete assignments is a
single-chip system control framework.
When the user operating the keyboard or a button switch, the
monitoring program must be interpreted for keyboard operation
and calls the corresponding function modules
Block to complete the scheduled tasks, and the display shows
the results of the implementation. Response systems in the
first moments of the system is running
Initialization,
which
includes
software
initialization
and
hardware initialization. SCM system at run time may also be
some pre-conditions
Trigger to complete the job, such as the timing signal, the
external trigger signal, etc.. Therefore, the monitoring program
should be able to complete the following features:
Room temperature to set the value
The actual room temperature value
Fuzzy controller to perform
Sensor
E at room temperature
Δ
Δt
ΔE
U
System initialization, processing keyboard commands to deal
with the interface command, and processing conditions trigger
and complete the display, at the appropriate time
Procedures for call control algorithms, and scheduling the task
execution module.
(5) the experimental verification
In order to verify hardware and software system design and
control strategy is feasible, I model machine experiments by
the experimental experience
Card, the system design in terms of control accuracy in
real-time tasks triggered aspects are in line with the design
standards to meet set
Design requirements.
6. Conclusion
In the small domestic gas boiler single chip control system,
intelligent fuzzy control algorithm than the PID control
algorithm and adaptive
PID control algorithm is simple, and can better meet the control
requirements. Powerful single chip control, combined with a
certain
Hardware circuits and control software, you can make small
domestic gas boiler control to improve the man-machine
interactive interface,
Control is more precise, to make intelligent, timed run of the
operating parameters of the system can be preset by the user,
mentioning
High performance and grade.
Author innovation: the use of embedded microcontrollers single-chip as the core of the original controller, fuzzy control
Based strategy to control the effect of intelligent features.
Has been brought to our hospital library subscribes to the
"Computer" magazine, has yet to be an annual subscription
time, not yet answer
Complex; I School of Automation Engineering, in the next year
to subscribe to a micro-computer information "on the library for
teachers and students to borrow.
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The furnace ,1998,3:71 -74.
[2] Zhou Lijian. Circulating water dynamic simulation device
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[3] Limin SCM Application Technology Selected [M] Beijing:
Beijing University of Aeronautics and Astronautics Press, 2000.
[4] Bao-sensor and its application [M] Beijing: Machinery
Industry Press, 2005.
[5] Ge Lusheng combustion systems, fuzzy control simulation
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Author:
Zhuhuan Li (1972 -), Anhui Huai, Yellow River Conservancy
Technical Institute, MA, lecturer, mainly engaged in
Electrical and mechanical electronic technology in teaching
and research work. (Henan University, Kaifeng 475003)
Biography: ZHU Huan-li (1972 -), man, Huaiyuan Anhui, Yellow
river conservancy
technical institute, teacher, master, Research area: electric &
mechatronics
technology.
Liu Yubin (1973 -), Huadian, Yellow River Conservancy
Technical Institute, MA, lecturer, mainly engaged in
Electrical and mechanical electronic technology in teaching
and research work. (Henan University, Kaifeng 475003)
Wangdian Long (1962 -) Yangzhong human, Dalian University
of Technology, Ph.D., professor, doctoral tutor, mainly
Engaged in surface CAD / CAM and sensor monitoring and
control aspects of teaching and research. (Dalian, Liaoning
116024, China)