CN201730811U - Photovoltaic water pump controller - Google Patents

Abstract

The utility model relates to a photovoltaic water pump controller. The structure of the utility model is that the output end of the solar battery panel is respectively connected to the switching power supply and the DC/DC circuit, and the switching power supply is connected to the control unit, the buffer isolator, the zero-crossing comparison circuit, the bus voltage and current detection circuit, the temperature detection circuit, and the water level dry detection circuit The DC/DC circuit is connected to the three-phase inverter bridge and then connected to the brushless DC motor and the zero-crossing comparison circuit. The control unit is respectively connected to the buffer isolator, communication interface, LCD screen, and indicator lights. After the buffer isolator is connected to the power drive circuit Connected to the three-phase inverter bridge circuit, the zero-crossing comparison circuit, the bus voltage and current detection circuit, the temperature detection circuit, the water level dry detection circuit, and the output terminals of the peripheral circuits are all connected to the input terminal of the control unit. It solves the defects of the constant voltage method, the disturbance observation method, and the increased conductance method, such as relatively large errors, unstable systems, and high costs. The utility model has simple operation and convenient maintenance, and realizes the maximum power tracking algorithm.

Description

Photovoltaic water pump controller

technical field

The utility model belongs to the technical field of solar photovoltaic water pump control, in particular to a photovoltaic water pump controller. the

Background technique

In rural and remote areas without electricity supply, electricity supply is required for irrigation. To this end, photovoltaic power generation technology has been developed, that is, the use of photovoltaic water pump control systems to rationally develop groundwater resources has solved the problems of drinking water and agricultural water in these areas to a certain extent, which will bring huge ecological and economic benefits to these areas. the

However, due to the overall high price of the photovoltaic water pump system, the promotion of the photovoltaic water pump system in rural and remote areas has been hindered to some extent. The main reason for the high price is the high cost of solar panels and batteries, and solar panels are essential, and the price has dropped with the development of technology. The storage battery mainly stores energy when the sunshine is strong, and releases energy when the sunshine is weak, but this is of no real significance to most remote areas, because drinking water and agricultural water are not needed all the time, unlike electricity demand. In addition, the price of an ordinary single battery is relatively high, and its service life is limited. the

The power generation efficiency of solar cells is not high at present. In order to improve the overall efficiency of the system, it is a good way to seek the maximum power output. In order to ensure the maximum output power under any sunlight intensity, the solar cell should always work on the maximum power point curve. As shown in Figure 1, the solar cell output characteristic curve is based on the solar cell output characteristic and the maximum power point curve characteristic. the

Before the invention of the utility model, the current maximum power tracking methods commonly used include: constant voltage method (CVT) tracking, perturbation and observation method (P&O), increased conductance method (INC) and so on. CVT control is simple and easy to implement, and the cost is low, but the error is relatively large with seasonal changes. P&O does not need to know the characteristics of the array and requires an iterative process, but the system cannot be stabilized at the maximum power point. INC calculation is accurate, which prevents misjudgment very well, but requires high-precision current and voltage sensors, and the cost is relatively high. the

Contents of the invention

The purpose of this utility model is to overcome the above defects and develop a photovoltaic water pump controller. the

The technical scheme of the utility model is:

Photovoltaic water pump controller, its main technical feature is that the output terminals of the solar panel are respectively connected to the switching power supply and the input terminal of the DC/DC circuit, and the output terminals of the switching power supply are respectively connected to the control unit, buffer isolator, zero-crossing comparison circuit, and bus voltage and current detection Circuit, temperature detection circuit, water level dry detection circuit, the output end of the DC/DC circuit is connected to the input end of the three-phase inverter bridge, and the output end of the three-phase inverter bridge is respectively connected to the input end of the brushless DC motor and the zero-crossing comparison circuit , the output end of the control unit is respectively connected to the input end of the buffer isolator, communication interface, LCD screen, and indicator light, the output end of the buffer isolator is connected to the input end of the power drive circuit, and the output end of the power drive circuit is connected to the three-phase inverter bridge The input end of the circuit, the zero crossing comparison circuit, the bus voltage and current detection circuit, the temperature detection circuit, the water level dry detection circuit and the output end of the peripheral circuit are all connected to the input end of the control unit. the

Advantage and effect of the present utility model are:

1. Use solar cells to convert light energy into electrical energy, output energy from photovoltaic arrays, transfer energy to brushless DC motors and water pumps through DC/DC converters, three-phase inverter bridges, etc., and lift water to the reservoir. the

2. It adopts a DC/DC topology hardware conversion link, and adopts a maximum power tracking algorithm - an improved adaptive hill climbing method. Although the control algorithm is complex, it is controlled by a computer, and the application is relatively simple and the calculation is accurate. Can achieve the maximum power output very well. the

3. Applied to photovoltaic water pump systems without batteries, which greatly reduces costs and requires a water storage tank. It is suitable for working at sunrise and resting at sunset. In addition, it has the characteristics of simple operation and convenient maintenance. the

4. With intelligent protection function, it can quickly respond to problems such as over-current, over-voltage, under-voltage, dryness, and high temperature, and protect the safety of the controller in time. the

The utility model realizes the maximum power tracking function, and the DC/DC circuit needs to be used in conjunction with the control unit to realize the maximum power tracking algorithm. the

Other advantages and effects of the present utility model will continue to be described below. the

Description of drawings

Figure 1 - Schematic diagram of the output characteristic curve of a solar cell. the

Fig. 2 - schematic diagram of circuit principle of the utility model. the

Fig. 3 - the schematic flow chart of the application main program of the utility model. the

Fig. 4 - schematic diagram of the principle of the zero-crossing comparison circuit in the utility model. the

Detailed ways

The controller of the present utility model will be further described below in conjunction with the accompanying drawings and embodiments. the

As shown in Figure 2:

The utility model is mainly composed of DC/DC circuit 2 (Buck circuit), switching power supply 3, temperature detection circuit 4, bus voltage and current detection circuit 5, water level dry detection circuit 6, control unit 16, peripheral circuit 7, human-computer interaction interface (Indicators and keyboard 8, LCD screen 10), communication interface 9, three-phase inverter bridge 11, power drive circuit 12, buffer isolator 13, zero-crossing comparison circuit 14. the

The output terminals of the external solar panel 1 are respectively connected to the switching power supply 3 and the input terminals of the DC/DC circuit 2, and the output terminals of the switching power supply 3 are respectively connected to the control unit 6, the buffer isolator 13, the zero-crossing comparison circuit 14, and the bus voltage and current detection circuit 5. The temperature detection circuit 4, the water level dry detection circuit 6, the output terminal of the DC/DC circuit 2 is connected to the input terminal of the three-phase inverter bridge 11, and the output terminal of the three-phase inverter bridge 11 is respectively connected to the brushless DC motor 15, the overdrive The input terminal of the zero comparison circuit 14 and the output terminal of the control unit 16 are respectively connected to the input terminals of the buffer isolator 13, the communication interface 9, the LCD screen 10, the indicator light and the keyboard 8, and the output terminal of the buffer isolator 13 is connected to the power drive circuit 12 The input end of the power drive circuit 12 is connected to the input end of the three-phase inverter bridge 11 circuit, the zero-crossing comparison circuit 14, the bus voltage and current detection circuit 5, the temperature detection circuit 4, the water level dry detection circuit 6, and the peripheral circuit The output terminals of 7 are all connected to the input terminals of the control unit 6. the

Two lines of wires lead out from the output end of the solar panel 1 are respectively connected to the DC/DC circuit 2 of the photovoltaic water pump controller and the input end of the switching power supply 3, and one line passes through the switching power supply 3 to output to the control unit 16, the buffer isolator 13, and the zero crossing Comparator circuit 14; the other is connected to the input end of the DC/DC circuit 2, and the output end of the DC/DC circuit 2 is connected to one end of the Hall voltage sensor in the bus voltage and current detection circuit 5, and the other end of the Hall current sensor is sent to To the three-phase inverter bridge 11. the

The six PWM pin output ends of the control unit 16 are connected to the input end of the buffer isolator 13, the output end of the buffer isolator 13 is connected to the input end of the power drive circuit 12, and the output end of the power drive circuit 12 is connected to the three-phase inverter bridge 11 The drains of the six MOS transistors in the circuit. Three wires from the three-phase inverter bridge 11 are connected to a brushless DC motor (BLDCM) 15 to drive the water pump. the

The three wires output from the three-phase inverter bridge 11 are also connected to the input terminal of the zero-crossing comparison circuit 14 , and its output terminal is connected to the external interrupt pin of the control unit 16 . Lead out from the thermistor on the heat sink connected with six MOS tubes to the input end of the temperature detection circuit 4 , and the output end of the temperature detection circuit 4 is connected to an A/D sampling pin of the control unit 16 . Lead out from the third terminal of the Hall current sensor, connect to the input end of the current detection circuit in the bus voltage and current detection circuit 5, and send the output end of the current detection circuit to another A/D sampling pin of the control unit 16. The front-end sampling resistor of the three-phase inverter bridge 11 is led to the input terminal of the voltage detection circuit, and the output terminal of the voltage detection circuit is connected to the third A/D sampling pin of the control unit 16 . the

The three wires for detecting the water level are connected to the input end of the water level dry detection circuit 6 , and the output end thereof is connected to another external interrupt pin of the control unit 16 . The peripheral circuit 7 is connected to the relevant pins of the control unit 16; the man-machine interaction interface (indicator light and keyboard 8, liquid crystal screen 10) is connected to the relevant I/O pins of the control unit 16; the communication interface 9 is connected to the RXD\TXD of the control unit 16 pin. the

First, the photovoltaic water pump controller is introduced from the output end of the external solar panel 1, and all the way through the switching power supply 3, the switching power supply 3 is mainly composed of DC-DC direct current conversion chip UC3842 and peripheral circuits, self-made transformer T1, transformer front-end input circuit, transformer front-end feedback Circuit, transformer four-way output circuit, 5V voltage regulator tube LM7805, 3.3V voltage regulator chip LM111733. The compensation of pin 1 of UC3842 is introduced by the front-end feedback circuit of the transformer through R77, R79, and C47; the voltage feedback of pin 2 is obtained by dividing the voltage through R77, R82, and adjustable resistor R85; , and then from the source to the small resistor R90, and then obtained after filtering by R87 and C52; the frequency of the internal oscillator is connected to pin 4 by R86 and C53; pin 6 outputs the control signal to Q8 to adjust the transformer input. The turns of the four output coils of the transformer need to be properly calculated to generate four power supplies: ±15V/15V/15V/3.3V. Output 3.3V to the control unit 16, output two channels of 15V to the optocoupler and other device blocks of the buffer isolator 13, and output +/-15V to the operational amplifier of the zero-crossing comparison circuit 14. the

The control unit 16 and its peripheral circuit 7 are DSP56F8037 control chip as the control core, which is responsible for the control of the entire controller, data acquisition and processing, the realization of the maximum power tracking algorithm, and software protection, etc., its main program flow diagram is shown in the accompanying drawing 3. Specifically, 6 channels of PWM waveforms are generated to control the rotor switching of the brushless DC motor, from open-loop control to closed-loop control, and the rotor position and current speed are calculated; temperature, voltage, and current signals are collected for comprehensive analysis and processing; one channel of PWM waveform control The MOS switch tube Q1 of the BuckDC/DC circuit 2 realizes the maximum power tracking algorithm; after receiving the back EMF zero-crossing signal, a certain lag compensation is performed, and the rotor switching time is adjusted; the hardware interrupt is handled, etc. the

The output terminals of the six PWM pins of the control unit 16 are connected to the input terminals of the buffer isolator 13, and the buffer isolator 13 is composed of a NAND gate SN7404 and a high-speed optocoupler. The 6 PWM waveforms are output from the control unit 16 and connected to the NAND gate to enhance the driving capability; then connected to a high-speed optocoupler for photoelectric isolation and then sent to the power drive circuit 12 . This circuit is mainly to prevent the current of the subsequent stage circuit from being too large due to control errors or other factors, and the busbars are short-circuited, causing the lines and devices to burn out; in addition, it can also prevent the control unit 16 from directly 6 channels at the same time when the controller is initially started or reset. output high level. the

The output end of the buffer isolator 13 is connected to the input end of the power driving circuit 12, and the power driving circuit 12 is mainly composed of a power MOSFET integrated driving circuit IR2130 and other auxiliary circuits. Buffer isolator 13 outputs six control signals to the input terminal of IR2130; uses resistor R63, rheostat R55, capacitor C3, and C32 to send the sampling current to the current detection circuit inside IR2130; the internal alarm of IR2130 is connected to the optocoupler U15 through pin 8, and finally Connect the 16-pin GPIOA6 of the control unit; because the power supply of the output driver of the 3-way driving high-voltage side power MOS device inside the IR2130 is obtained through the bootstrap technology, in order to prevent the voltage discharge at both ends of the bootstrap capacitor, a fast recovery diode BYV26E is selected . In addition, DC/DC is used for bootstrapping to supply power to the suspension power supply, which avoids the shortcoming of the slow response speed of the bootstrap capacitor and improves the reliability of the system. the

After passing through the IR2130, connect the three-phase inverter bridge 11 circuit. The three-phase inverter bridge 11 is composed of 6 MOS switching tubes and 6 fast recovery diodes, forming three upper and lower bridge arms. Q2, Q3, Q4 are upper bridge arms, Q5, Q6, Q7 are lower bridge arms, and 6 fast recovery diodes are respectively connected in parallel on 6 MOS switch tubes. The drains of the three upper bridge arm MOS switch tubes are connected together to the positive pole of the output terminal of the DC/DC circuit 2, and the sources of the three lower bridge arm MOS switch tubes are together connected to the negative pole of the output terminal of the DC/DC circuit 2. The gates of the six MOS switch tubes are connected to the output terminals HG1 , HG2 , HG3 , LG1 , LG2 and LG3 of the power drive circuit 12 respectively. The middle of the upper and lower bridge arms on the three roads respectively output three wires U, V and W to connect to the brushless DC motor (BLDCM) 15, thereby driving the water pump. the

The other way from the output end of the external solar panel 1 is connected to the input end of the DC/DC circuit 2. The DC/DC circuit 2 shown is a Buck step-down circuit, which consists of a MOS switch tube Q1, an inductance coil L1, a diode D2, and a large capacitor. C2 composition. The solar panel 1 outputs to the source of the MOS switching transistor Q1, and a pin of the control unit 16 is connected to the drain of the MOS transistor Q1 in the DC/DC circuit as a control signal. The gate is connected to one end of the inductance coil L1 and connected to the negative pole of the diode D2. The other end of L1 is connected to the positive pole of the capacitor C2 and drawn out as a bus voltage to the inverter bridge. The other ends of D2 and C2 are connected to the ground at the same time. The selection of the inductance coil L1 of this circuit is very important. the

The output end of the DC/DC circuit 2 is connected to one end of the Hall current sensor in the bus voltage and current detection circuit 5, and the other end of the Hall current sensor is sent to the positive and negative poles of the three-phase inverter bridge 11 as a bus. The three wires U, V, and W output from the three-phase inverter bridge 11 are also connected to the input terminal of the zero-crossing comparison circuit 14, which corresponds to the sensorless brushless DC motor 15. The brushless DC motor 15 is used in the photovoltaic water pump system, because of its good mechanical properties, large starting torque, wide speed range, relatively simple control, and higher operating efficiency than other types of motors. In addition, the system generally requires the motor to operate submerged in water, and the selection of the position sensorless brushless DC motor 15 is an ideal choice for the photovoltaic water pump system. However, the detection of the rotor position when the brushless DC motor 15 is in operation is a difficult problem, and the detection of the zero-crossing point of the back EMF can solve the problem well. The zero-crossing comparison circuit 14 is mainly composed of a high-speed, linear optocoupler, a filter circuit, a zero-crossing comparator, and the like. As shown in Figure 4, the back EMF signal is dropped by the linear optocoupler, the DC component is filtered by the DC blocking circuit, and then sent to the zero-crossing comparator after passing through the first-order filter circuit, and finally the obtained signal is finally sent to the control External interrupt pin of unit 16 for nice switching of motors. In addition, due to the existence of filter circuits, the corresponding hysteresis needs to be compensated by software. the

Lead out from the thermistor on the heat sink connected with six MOS tubes to the input end of the temperature detection circuit 4 , and the output end of the temperature detection circuit 4 is connected to an A/D sampling pin of the control unit 16 . The temperature detection circuit 4 is connected to the thermistor R13 on the heat sink of the controller. After proper voltage adjustment, it is connected to R334, C313, and C314 for filtering, and then U5 op amp LM358 to the A/D port ANA4 of the control unit 16. the

The bus voltage and current detection circuit is divided into two parts. The input terminal of the current detection circuit is connected to the front-end sampling resistor R4 of the three-phase inverter bridge 11. After being isolated by D4 and the linear optocoupler U2, the step-down is connected to U3 and the operational amplifier LM358 is connected to the control The A/D sampling pin ANA0 of unit 16; the current detection circuit outputs a small current through the third terminal of the Hall current sensor, and connects R330, R331, C12, and C312 to filter after voltage division and pressure, and then connects U6 operational amplifier LM358 to the control Another A/D sampling pin ANA1 of unit 16. the

The three wires for detecting the water level are connected to the input end of the water level dry detection circuit 6 , and the output end thereof is connected to another external interrupt pin of the control unit 16 . The water level detection circuit 6 detects the height of the current water level by three wire terminals WH, WL, and CM, wherein the WH water level is the highest, which is the water level at which the water pump stops; the WL water level station is the water level at which the water pump is started; CM is the common terminal at the very bottom. WH is connected to +15V power supply, there is a water level difference between WH and WL, which constitutes a hysteresis loop for water level detection, so as to avoid frequent switching of the motor when the water level fluctuates up and down. The whole water level dry detection circuit 6 is made up of resistors R117, R119, capacitor C65, optocoupler U25, U24 operational amplifier LM358. the

The human-computer interaction interface (indicator lights and keyboard 8, LCD screen 10) is connected to the relevant I/O pins of the control unit 16; it provides convenient operations such as controller status indication, relevant data playback, and parameter setting for the operator. The indicator light consists of three LEDs, DS1 indicates normal operation, DS2 indicates system failure, and DS3 indicates water level and alarm. The keyboard of indicator light and keyboard 8 is made of 4*4 keys supported by chip HD7279. The liquid crystal screen 10 is realized by the model number 12864 with font library, and it is used in conjunction with the keyboard to set and modify the relevant parameters of the control unit 16. the

The communication interface 9 is connected to the RXD\TXD pins of the control unit 16 . It provides the possibility for future software upgrades, data uploads, and networking control. The control unit 16 uses the driver chip MAX232 conforming to the RS-232 standard protocol for communication. A voltage conversion circuit must be added between the chip MAX232 and DSP56F8037, and a resistor is selected to step down. The serial port is configured with a baud rate of 9600b/t, a start bit, a stop bit, and a parity bit; the RS232/RS485 transfer interface can be used later to carry out RS485 protocol transmission signals. the

Claims (7)

1. photovoltaic water pump controller, it is characterized in that the solar panel output terminal connects switch power respectively, the input end of DC/DC circuit, the switch power output terminal connects control unit respectively, buffer isolator, the zero passage comparison circuit, the busbar voltage current detection circuit, temperature sensing circuit, water level is beaten dried testing circuit, the DC/DC circuit output end connects the input end of three phase inverter bridge, the output terminal of three phase inverter bridge connects brshless DC motor respectively, the input end of zero passage comparison circuit, the output terminal of control unit connects buffer isolator respectively, communication interface, liquid crystal screen, the input end of tutorial light, the input end of the output termination power driving circuit of buffer isolator, the output terminal of power driving circuit connects the input end of three-phase inversion bridge circuit, zero passage comparison circuit, the busbar voltage current detection circuit, temperature sensing circuit, water level is beaten dried testing circuit, the output terminal of peripheral circuit is all received the input end of control unit.

2. photovoltaic water pump controller according to claim 1 is characterized in that the DC/DC circuit is the Buck reduction voltage circuit, is made up of MOS switching tube Q1, inductance coil L1, diode D2, big capacitor C 2; Solar panel outputs to the source electrode of MOS switching tube Q1, is connected the drain electrode of the metal-oxide-semiconductor Q1 in the DC/DC circuit by a pin of control unit; Grid connects the end of inductance coil L1, and links to each other with the negative pole of diode D2, and the positive pole of another termination capacitor C 2 of L1 is also drawn as busbar voltage and given inverter bridge, and the other end of D2, C2 links to each other with ground simultaneously.

3. photovoltaic water pump controller according to claim 1 is characterized in that the zero passage comparison circuit mainly is by high speed, linear optical coupling, eliminator, and zero-crossing comparator is formed; Behind the three phase inverter bridge output terminal process linear optical coupling U16, connect capacitor C 56, deliver to zero-crossing comparator U17 behind the eliminator through R95, C57 composition again, the signal of Huo Deing is finally delivered to the external interrupt pin of control unit the most at last.

4. photovoltaic water pump controller according to claim 1 is characterized in that switch power mainly is made of DC converting chip UC3842 and peripheral circuit, self-control transformer T1, transformer front end input circlult, transformer front end feeder loop, transformer No. four output circuits, 5V voltage-stabiliser tube LM7805,3.3V voltage stabilizing sheet LM111733; The 1 pin compensation of UC3842 is introduced through R77, R79, C47 by transformer front end feeder loop; 2 pin voltage feed back are to obtain through R77, R82, adjustable resistance R85 dividing potential drop; 3 pin current samplings are to cause Q8 by transformer front end input two-terminal, again from source electrode to small resistor R90, again by obtaining after R87, the C52 filtering; Insert inner vibrator frequency and be connected to 4 pin by R86, C53; 6 pin output control signals to Q8, adjust the transformer input.

5. photovoltaic water pump controller according to claim 1, it is characterized in that six PWM pin output terminals of control unit connect the input end of buffer isolator, the output terminal of buffer isolator connects the input end of power driving circuit, the output terminal of power driving circuit connects the drain electrode of six metal-oxide-semiconductors in the three-phase inversion bridge circuit, and three phase inverter bridge is drawn three leads and connected brshless DC motor.

6. photovoltaic water pump controller according to claim 1 and 2, it is characterized in that drawing from the 3rd terminal of the Hall current sensor of DC/DC circuit input end, be connected to the input end of current detection circuit in the busbar voltage current detection circuit, the output terminal of current detection circuit is delivered to another A/D sampling pin of control unit, lead to the input end of voltage detecting circuit from the front-end sampling resistance of three phase inverter bridge, the output terminal of voltage detecting circuit is connected the 3rd A/D sampling pin of control unit.

7. photovoltaic water pump controller according to claim 1, it is characterized in that water level beaten that three leads of sensed water level are connected to the input end that water level is beaten dried testing circuit in the dried testing circuit, the output terminal of beating dried testing circuit from water level is connected to another external interrupt pin of control unit; Water level is beaten dried testing circuit and is made up of resistance R 117, R119, capacitor C 65, optocoupler U25, U24 amplifier LM358.

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