Camping cooling and heating fan circuit board development

At present, in camping operations such as mines, electric power, exploration, and environmental protection, the heating and ventilation of the tents or temporary simple houses where the staff live is a problem, and the power and portability of general air conditioners are difficult to meet the requirements. Most of the cooling and heating fans for field work in my country are refitted, and it is difficult to meet the needs of field work. In view of the special environment of each field operation, the author has developed an intelligent control system that is suitable for field operation cooling and heating fans and has the requirements of "moisture-proof, smoke-proof, and mold-proof". Cooling and heating control of the fan, and has a voice prompt function for various faults and operations of the equipment.

1. Hardware system design of camping cooling and heating fan intelligent controller

1.1 The composition and basic principle of the camping cooling and heating fan intelligent control system

The camping cooling and heating fan system is mainly composed of an axial fan, a compressor, a blower, a dry filter, a four-way reversing valve, a throttling component, an evaporator, and a condenser. Among them, the axial flow fan, compressor, blower, and four-way reversing valve are the executive components. Therefore, the main function of the camping cooling and heating fan intelligent control system is to complete the control of these executive components. The intelligent control system of cooling and heating fans consists of an outdoor master controller and an indoor controller. The outdoor main controller mainly monitors and collects the temperature and high and low pressure distributed in different parts of the air conditioner according to the working principle of air conditioner control, so as to realize the normal operation of the fan. The indoor controller includes control and voice parts. The outdoor main controller transmits the measured parameters to the indoor controller through a four-core cable, and operates the air conditioner indoors as required. The indoor controller can display all parameters and faults at the same time. Tips, how-to.

1.2 Design of outdoor main controller of fan

The outdoor master controller uses PIC16F77 single-chip microcomputer as the main control element, which is mainly composed of signal acquisition, watchdog circuit, keyboard and display circuit, output circuit, power supply circuit and so on. After the system is powered on, the control system monitors and collects the temperature and high and low pressures distributed in different parts of the air conditioner to realize the cooling or heating of the fan.

The signal acquisition part mainly collects signals such as temperature, voltage, frequency, pressure and axial flow fan current.

1) Temperature acquisition circuit: use a thermistor to measure each temperature. A thermistor is a thermosensitive type of temperature sensing element made of a solid semiconductor material with a high temperature coefficient of resistance. The design selects a negative temperature coefficient thermistor and uses a voltage divider circuit to measure the temperature, and the detection results are processed and input to the RA port.

2) Current signal acquisition circuit: TA12-100 epoxy potting precision current transformer is selected for current acquisition. TA12-100 epoxy potting precision current transformer, transformation ratio 1000:1, 0~5mA output, can be used as the input signal of the electric control system to monitor the running state of the motor.

3) Pressure signal acquisition circuit: The control system needs to monitor the high pressure and low pressure values of the compressor. The selected JPG2 diffusion silicon oil-filled core pressure sensor has an output signal of 4-20mA or 1-5V, which can be directly connected to the RA port of PIC16F77.

The output drive circuit is mainly to control actuators such as compressors, axial fans and four-way valves. Use RC4, RC5 and some RD lines to amplify the output signal and drive the relay to control the corresponding actuators.

1.3 Fan indoor controller design

The indoor controller adopts PIC series microcontroller PIC16C711. The design principles of its power supply circuit, reset circuit, keyboard and display circuit are similar to those of the outdoor master controller. The focus here is on the speech system.

Cooling and heating fans in field work are used in a wide range, and the education level of the users is low. In addition, the personnel in field work units are highly mobile, and generally there is no special person for operation and maintenance. Therefore, the best way to solve this problem is to increase the voice prompt function to make the equipment truly Be a "fool". The MSP53C392 passive speech synthesizer produced by TI is selected, which is a speech synthesis system controlled by a single-chip microcomputer. Various speech synthesis algorithms are integrated in the chip, and users can choose according to their requirements. Utilize PC and TI's special software to convert and compress the voice data, and then download it to the Flash memory. Use single-chip microcomputer PIC16C711 to read voice data through table lookup, output voice through MSP53C392 synthesis, and then drive the speaker after filtering and LM386 power amplification.

2. Software system design of camping cooling and heating fan controller

2.1 Switch program design

1) Start-up process: Refrigeration start-up process: The temperature inside the tent is controlled by start-stop. When the return air temperature (tent temperature) is higher than the user's set temperature plus the hysteresis, if the time from the previous shutdown exceeds 180s, the shaft will be turned on. Flow fan, delay 30s, turn on the compressor; when the return air temperature is lower than the user's set temperature minus the hysteresis, turn off the compressor, delay 5s to turn off the axial fan. The heating start-up process is similar to the cooling process.

2) Shutdown process: Shutdown process: Shutdown signal, turn off the compressor, delay 5s, turn off the axial flow fan, delay 10s, turn off the blower, and the shutdown is over.

2.2 Refrigeration and heating process program design

According to the refrigeration principle, after the system is powered on, it first checks whether the working voltage (200-240V), frequency, current, and pressure are normal. If the system is not normal, it will display fault information (if the voltage, frequency, high and low voltage are not normal, it will stop, and if the temperature sensor is not normal, it will only display fault information). The heating process program flow is similar to cooling.

2.3 Voice Prompt Software Design

The main function of the voice prompt software is to initialize the system, read different voice segment data according to different key inputs, communicate with the voice synthesizer, transmit voice data, complete the reset of the voice synthesis device and other controls. Perform low-pass filtering through GOLDWAVE software to make its bandwidth 4kHz or 5kHz, and then re-sample at 8kHz or 10kHz; at the same time, adjust the volume and save it in 16-bit mono-channel PCM data format. The converted and compressed data are saved in 24LC512 and 24LC256.

3. Structural design of heater controller

The controller has taken corresponding reinforcement measures for various harsh environments. The shell material is made of aluminum and stainless steel, and the iron parts are hot-dip galvanized. The thickness of the coating is more than 10 times that of ordinary electroplating, so as to achieve moisture-proof and smoke-proof and anti-mold. The keyboard uses new high-elastic stainless steel as the shrapnel of the keys. The keys are easy to install, convenient and reliable, with long life and good hand feeling.

Summarize

The camping cooling and heating fan intelligent control system is mainly developed for the unique climatic conditions in field operations. The system realizes the control of the high-power cooling and heating fan system, and a voice prompt function is designed. This function can prompt the operation method and fault type to help the user The personnel can easily control it, making the equipment truly "fool-like". The application of this system will effectively provide better logistics support for field operation units.

The above is the development example of the cooling and heating fan introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have camping heater program development needs, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, MCU development, Bluetooth solution, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.