基于PIC单片机的光伏控制器的设计与制作

科技论文题 目：基于 PIC 单片机光伏控制器的设计系 别 电子技术学院 专 业 光伏应用技术 班 级 学生姓名 学 号 2017 年 12 月Based on PIC MCU of design for PV controllerAbstract: The full name of solar controller is solar charge and discharge controller, which is used in solar power system to control the solar battery (square matrix) to charge the battery, and the battery to the solar inverter load automatic control equipment. PIC microcontroller photovoltaic controller, it is lightweight, highly maneuverable. Design mainly from the controller requirements, the controller hardware circuit design, the controller software circuit design and debugging and summary of four aspects. After a series of experiments, the following conclusions are drawn: The PIC12F675 single-chip microcomputer as a control chip in the photovoltaic controller has the advantages of reliable solution, stable performance, high conversion efficiency, convenient and reliable, good practicability, low cost and safety, and effective implementation The rational use of solar energy resources to meet user needs.Key words: PIC microcontroller; photovoltaic controller; automatic controlForewordWith the development of science and technology, the progress of society and the improvement of human living standards, non-renewable resources on the earth will also be consumed continuously. As a result, people will consider looking for renewable clean energy, so the solar energy is slowly developed. At present, solar power generation is a mainstream in todays world, and there are a variety of photovoltaic products on the market such as solar roofs, solar calculators, solar chargers and the like. These products have a photovoltaic power generation system, then in the photovoltaic power generation system, photovoltaic controller is one of the important components. What kind of PV controller to meet peoples needs? Of course, stable performance, high conversion efficiency, convenient and reliable, practicality, safety and low cost of PIC microcontroller PV controller. This raises the question of how such a PV controller should be designed. Therefore, the following design is provided. 一、 Requirements of Controller1、The controller to achieve the basic functions Battery overcharge and over discharge protectionOvercharge protection: When the charging voltage is higher than the protection voltage, the battery is automatically shut off. After that, when the voltage drops to the maintenance voltage, the battery enters the floating state. When the voltage drops below the recovery voltage, it floats off and enters the fully charged state.Over-discharge protection: When the battery voltage is lower than the protection voltage, the controller automatically shut down the output to protect the battery from damage; when the battery is recharged, but also automatically restore power supply. Automatic recovery discharge functionAuto-recovery discharge function refers to the function of the controller that automatically helps to restore normal discharge after over-discharge of the battery. Prevent the battery and solar battery reverse functionBattery “+“ “-“ polarity reversed, the fuse blown, after replacement can continue to use.2、The controller circuit parameters Maximum charge current (A): 5The maximum charge current is the maximum current the controller is charging. Maximum discharge current (A): 5The maximum discharge current is the maximum current when the controller is in a discharged state. Battery rated voltage (V): 12Battery for a long time the best working voltage, rated voltage is also known as the nominal voltage. When the battery voltage is higher than the rated voltage easily damaged equipment, and below the rated voltage will not be normal power supply. Solar cell rated output voltage (V): 18The best output voltage of the solar cell during normal operation is called the rated output voltage of the solar cell. Solar cell maximum open circuit voltage (V): 25The solar cell is placed in the AM1.5 spectral conditions, 100 mW / cm2 light source irradiation, open both ends, the maximum output voltage of the solar cell. Overcharge voltage (V): 14.8Overcharge voltage is more than the rated voltage of the battery, the charging voltage within a short time. Over discharge voltage (V): 10.8Over-discharge voltage is more than the rated voltage of the battery, a short period of discharge voltage.二、 Design of Photovoltaic Controller Hardware CircuitThe PV controller system uses the rated output voltage of 18V photovoltaic panels, equipped with 12V battery, PV panel power and battery capacity can be determined according to actual needs, taking into account the charging time and the length of time for electricity to be reasonable With, such as the rated output power of 10W photovoltaic panels with 10Ah battery more appropriate.Photovoltaic power generation system controller circuit shown in Figure 2-1. System hardware circuit by the discharge control circuit, microcontroller circuit, charging control circuit and other components.Figure 2-1 Photovoltaic controller circuit principle1、Microcontroller circuitIC1, R9, C3, etc. Make up the minimum system circuit of the one-chip computer, among them R9, C3 are the power up and resetting the circuit, IC uses PIC12F675, although it has only 8 pins, the function is more powerful, the pin is shown as 2-2.Figure 2-2 PIC12F675 microcontroller pinPIC12F675 chip contains 1KB of Flash ROM program memory, 64B of data memory RAM and 128B of EEPROM, operating speed of 0 20MHz, operating voltage of 2 5.5V. There are six I / O pins GP0 and GP5 with alternate functions.PIC12F675 can choose external or internal oscillator, where the use of an internal oscillator, the operating frequency of 4MHz. The chip has an 8-bit timer / counter with an 8-bit programmable pre-scaler and a 16-bit timer / counter with a pre-scaler, Timer1, a watchdog timer, 4-channel 10-bit A / D converter, an analog comparator.VT5, VT6 and other components of the charge control circuit, when the PIC12F675s GP2 pin output low, VT5 deadline, VT6 saturated conduction, solar battery through VD9, VT6 to the battery charge.VT1, VT2 and VT3, VT4, respectively, constitute two battery discharge control circuit, the use of two load can increase the use of flexibility, when the program on the PIC12F675s GP4, GP5 feet take different controls can achieve different functions, such as GP4 For routine control, GP5 increase night light control function, only in dark after external battery power supply. GP4, GPS If you use the same control functions, the two outputs can also be used in parallel. To the first road (load 1), for example, when the GP5 output low, the battery through VD8, VT1 power supply to the load.2、Charge and discharge control circuitThe charge-discharge control circuit measures the voltage of the battery by A / D conversion, that is, the voltage of the battery is firstly converted into data, and then the test data and the stored overcharge voltage and overdischarge voltage are recovered; and the data are compared, According to the comparison results to make the appropriate control. Circuit R11, R12 and R15, R16, respectively, composed of battery and solar cell voltage sampling circuit, solar cell sampling circuit to increase the use of night light control. The GP0, GP1 of PIC12F675 make the analog signal input port of two pass-way A / D converters respectively.A / D converter reference voltage to select the microcontrollers internal VDD, that is 5V as the reference voltage.R10, VD5, C1, C2 microcontroller 5V power supply.VD7, fuse anti-battery reverse circuit, when the battery is reversed VD7 conduction through the fuse short-circuit the battery, blowing off the fuse, so the battery circuit, play a role in protecting the circuit and load. Fuse also play an overload protection.VD9 prevents the solar panels from being reversed.3、work processConnected to the solar panels and batteries, the circuits work is as follows (set the battery voltage U):Charge working conditions:When U14.8V GP2 output low, the solar battery to charge the battery;When U 14.8V GP2 output high, the battery stops charging.Discharge work:1) When U falls from 12.3V to 10.8V, GP4 and GP5 output low level, and the battery discharges to the load.2) When U10.8V, GP4, GP5 output high, the battery stops discharging the load.3) U With the gradual increase in charging, when U 10.8V, the circuit does not immediately restore the battery power supply, otherwise it will be in a very short period of time due to the voltage drop and stop the power supply, the formation of an oscillating power supply state, that is, for a while Pass a break, in order to solve this problem, set a voltage hysteresis, when the battery charge is restored to U 12.3V, GP4, GP5 then output low to restore power supply.4、Hardware assembly processAccording to the schematic in the universal board to install the welding components and connections. Components of the model specifications and the number of see Table 4-1.Table 4-1 Parts Model Specification and Quantity TableNumber Components Number Model Number1 Single Chip computerIC pic12f675 12 Resistors R10 Metal Film 1/4w $number 13 Resistors R7 , R8 Metal Film 1/8w 1K 24 Resistors R1 , R4 , R12 , R16 Metal Film 1/8w 2K 45 Resistors R11 Metal Film 1/8w 6.2K 16 Resistors R15 Metal Film 1/8w 6.8K 17 Resistors R2 , R5 , R9 , R13 Metal Film 1/8w 10K 48 Resistors R3 , R6 , R14 Metal Film 1/8w 20K 39 Capacitor C2 Porcelain Sheet 0.1 F 110 Electrolytic C1 $number f/16v 111 Electrolytic C3 Ten f/16v 112 Diode VD1 , VD2 , VD6 10V Zener Diode 313 Diode VD5 5V Zener Diode 114 Diode VD7 1n5401 115 Diode VD8 , VD9 SB560 (5A 60V) 216 Light-emitting DiodeVD3 Green 117 Light-emitting DiodeVD4 Red 118 Transistor VT2 , VT4 , VT5 2sc945 319 Field Effect Tube VT1 , VT3 , VT6 IRF3205 320 IC Sockets DIP8 121 Fuse FUSE 5 A 122 Circuit board PCB Board 1三、 Design of Photovoltaic Controller SoftwareThe software mainly by the PIC microcontroller program, the program design flow shown in Figure 3-1. The program is compiled in the MPLAB IDE compiler and written in assembly language. Program consists of main program, timer interrupt service subroutine, A / D conversion subroutine, delay subroutine, numerical comparison subroutine, etc. The routine of interrupt service subroutine is shown in Figure 3-2.Figure 3-1 program design flow Figure 3-2 timer interrupt service routine design flowThe main program is mainly used to initialize, set the working mode of the microcontroller, a variety of control voltage is