CN2305016Y - D/A convertor for pump driven by photocell - Google Patents

Abstract

The utility model relates to a D/A convertor for a pump driven by a photocell, comprising a casing 1, a on-off power supply circuit 2 arranged in the casing, a PWM frequency conversion control circuit 4, a protection control circuit 5, a level shift circuit 6, an overheat protection circuit 7, an excess voltage protection circuit 8, an over current short protection circuit 10, a drive circuit 11, a main circuit 12, a current sampling circuit 13, a photoelectric isolation circuit 14, and a manual on-off circuit 15. The D/A convertor for a pump driven by a photocell is characterized in that a maximum power point tracking circuit 3 and a drying protection circuit 9 are also arranged. The utility model can extract the maximum power from a solar cell array at any time, and has a drying protection function.

Description

The photovoltaic water pump inverter

The utility model relates to a kind of frequency conversion inversion speed-governing control device of immersible pump, particularly relates to a kind of solar photovoltaic water pump inverter.

Solar cell utilizes photovoltaic effect that solar energy is transformed into electric energy.The water pump that designs for adaptation solar cell output characteristic is called photovoltaic water pump.It is different with the conventional diving pump, in order to optimize the optimum Match between motor and water pump and the solar cell, and guarantees the long-term unattended high reliability of photovoltaic water pump, all with the conventional diving pump certain difference is arranged from the electromagnetic parameter and even the overall structure of motor.Conventional diving pump so that ac three-phase asynchronous motor drives can utilize general variable frequency inverter to carry out variable frequency regulating speed control, to reach purpose energy-conservation and the protection motor and water pump.It is that--mode conversion of straight--hand over or hand over--friendship becomes voltage and frequency all with the alternating current of load variations to hand over the civil power of voltage and fixed-frequency, and the photovoltaic water pump that ac three-phase asynchronous motor drives is powered with solar cell, because solar cell output is the direct current that changes with intensity of sunshine, controlling this photovoltaic water pump, to only depend on the frequency conversion inversion transformation technique be not enough, must consider the output characteristic of solar cell.

The output characteristic curve of solar cell under different intensity of sunshines as shown in Figure 1, it is according to U.I product maximum principle, obtains a series of maximum power points, and these points are unified into the maximum power point curve that line is a solar cell.In order to guarantee that solar cell when intensity of sunshine is done to change arbitrarily, all has peak power output, solar cell is always worked on the maximum power point curve.Therefore, in the solar photovoltaic water pump system, must design a kind of special-purpose frequency conversion inverter controller with MPPT maximum power point tracking function.MPPT maximum power point tracking, English are referred to as MPPT (MAXIMPOWER POINT TRACK).

According to solar cell output characteristic and maximum power point curve character, the maximal power tracing mode has two kinds: the one, and decide voltage (CVT) and follow the tracks of, the 2nd, moving voltage (DVT) is followed the tracks of.Two kinds of methods compare, and CVT control realizes that easily cost is low, the circuit reliability height.DVT tracking accuracy height, but controlling schemes complexity must use high-precision current voltage sensor and microprocessor, cost height.

Chinese patent 92231841 discloses a kind of solar energy immersible pump adapter, its maximal power tracing function is placed on the DC-DC transform part, form with DC chopped-wave realizes, recommend with two power MOS pipes again and be reverse into single-phase alternating current supply monophase machine, its deficiency is to drive the single phase alternating current (A.C.) pump, can not drive the three-phase alternating current pump, tracking accuracy and reliability are lower.And in the prior art all dry pump beat dried protective circuit, thereby can't avoid the anhydrous idle running of water pump and wear and tear, and reduce the useful life of water pump.

The purpose of this utility model is to provide a kind of optimum Match that can realize photovoltaic water pump and solar cell, the photovoltaic water pump inverter that makes photovoltaic water pump can both extract maximum power and have low cost, high reliability from solar cell at any time; The purpose of this utility model also is to make this photovoltaic water pump to have and beats the function of doing protection, to adapt to its long-term unattended operational environment.

The purpose of this utility model can realize by following technical solution: the utility model comprises housing 1, is contained inswitching power circuit 2, PWM frequency conversion control circuit 4,protection control circuit 5, level shifting circuit 6, overheating protection circuit 7, under-voltage protecting circuit 8, short circuit over-currentprotection circuit 10, drive circuit 11,main circuit 12,current sampling circuit 13,photoelectric isolating circuit 14 and manual control switch'scircuit 15 in the housing, and main points of the present utility model are also to be provided with MPPT maximum powerpoint tracking circuit 3 and beat dried protective circuit 9.Described overheating protection circuit 7 is serially connected with between solar cell and theswitching power circuit 2; The input of MPPT maximum powerpoint tracking circuit 3 links to each other with main circuit 11 with solar cell, and its output then links to each other with PWM frequency conversion control circuit 4; PWM frequency conversion control circuit 4, under-voltage protecting circuit 8, the output of beating driedprotective circuit 9, short circuit over-currentprotection circuit 10 and manual control switch'scircuit 15 link to each other with the control end ofprotection control circuit 5; Level shifting circuit 6 inputs link to each other with the output ofprotection control circuit 5, and its output links to each other with drive circuit 11;Main circuit 12 inputs link to each other with drive circuit 11 outputs, and its output links to each other with the motor windings of photovoltaic water pump.The input ofcurrent sampling circuit 13 links to each other withmain circuit 12, and its output links to each other withphotoelectric isolating circuit 14, and the input of short circuit over-currentprotection circuit 10 links to each other withphotoelectric isolating circuit 14, and its output links to each other with drive circuit 11 withprotection control circuit 5

Described MPPT maximum power point tracking circuit mainly is made up of operational amplifier A 1, resistance R 1, R2, R3, R4, R5, R6 and capacitor C 1, its input links to each other withmain circuit 12 with solar cell array respectively by dividing potential drop sampling resistor R1, R2, R3, and its output then links to each other with PWM frequency conversion control circuit 4.

Describedly beat driedprotective circuit 9 and compriseoperational amplifier A 2; resistance R 7; R8; R9; R10; R11; R12; R13;capacitor C 2; E1; voltage-stabiliser tube Z1; diode D1; D2; transistor T 1; relay J (normally-closed contact J2; normally opened contact J1); LED 1 and three beat and do protection probe H; M; L; wherein an end ofresistance R 8 links to each other with coil one end of relay J; and join with one group of 12V out-put supply of switching power circuit (2); another group 12V out-put supply of the end of the normally open contact J1 of relay and switching power circuit (2) joins; its other end links to each other with the positive pole of diode D2; the negative pole of diode D2 links to each other with the control end of protection control circuit (5);resistance R 13 and LED 1 are connected between the positive pole and solar cell array negative pole of diode D2; beating to do protects probe H to link to each other with relay normally closed interlock J2 one end and resistance R 7 one ends; beating the other end of doing protection probe M and relay normally closed interlock J2 joins; beat and do protection probe L and beat joining of dried protective circuit (9) publicly, probe H; M; L places the top of photovoltaic water pump respectively; top and bottom.

Describedswitching power circuit 2, PWM frequency conversion control circuit 4,protection control circuit 5, level shifting circuit 6, overheating protection circuit 7, under-voltage protectingcircuit 8, short circuit over-currentprotection circuit 10, drive circuit 11,main circuit 12,current sampling circuit 13,photoelectric isolating circuit 14 and manual control switch'scircuit 15 all can adopt the circuit similar to custom circuit.

The function of each circuit of the utility model and act on as follows:

(1), switching power circuit 1. these circuit export two road independent stable 12V DC power supply, the one tunnel provides operating voltage for beating driedprotective circuit 9, another road provides 12V operating voltage for circuit such as MPPT maximum power point tracking circuit and PWM variable frequency control.

(2), MPPT maximum powerpoint tracking circuit 3. these circuit remain on the voltage of the current maximum power point of solar cell the dc voltage of inverter by PI adjusting control technology, thereby make solar cell can both provide energy to greatest extent to photovoltaic water pump at any time, allow photovoltaic water pump raise out more water.

(3), PWM frequency conversion control circuit 4. these circuit are accepted the voltage signal with strong and weak variation at sunshine that the MPPT maximum power point tracking circuit sends.Through VCO and pulse-width modulation conversion; output three-phase six road pulse-width signals are to protection control circuit and even drive circuit; make main circuit output voltage and frequency size all with the strong and weak three-phase alternating current that changes at sunshine, thus the control purpose that realization is carried out frequency control to photovoltaic water pump.

(4),protection control circuit 5. these circuit are to allow the protection control signal of protective circuits such as beating dried protection, overtemperature protection, under-voltage and overcurrent all be pooled to the control end of protection control circuit; in a single day this end receives the protection control signal; just cut off three-phase six tunnel control signals that arrive main circuit at once, realize the purpose of protection inverter itself and photovoltaic water pump.

(5), level shifting circuit 6. these circuit are to protect the level signal of three-phase six road TTL of control circuit output to convert the COMS level to, to offer drive circuit.

(6), overheating protection circuit 7. these circuit functions are when temperature on the radiator of inverter surpasses 75 ℃; cut off getting in touch of solar cell and switching power circuit; switching power circuit is quit work, and then whole circuit are quit work, realize overtemperature protection inverter.

(7), under-voltage protectingcircuit 8. when sunshine is low, the solar cell both end voltage is also lower, this moment, inverter work was meaningless, thereby under-voltage protecting circuit is not worked inverter.After sunshine, intensity reached a certain numerical value, inverter was started working automatically.In addition, when 12V operating voltage in the inverter circuit obviously reduced because of certain reason, under-voltage protecting circuit also played a protective role, when avoiding the circuit irregular working and damage components and parts.

(8), to beat driedprotective circuit 9. these circuit functions be when water level is pumped down to the photovoltaic water pump inlet opening, prevent the idle running of water pump lack of water and damage parts such as motor and impeller, thereby inverter and water pump are quit work automatically.After water level rose to certain altitude, inverter was started working automatically, and water pump pumps up water again.

(9), overcurrent and short-circuit protection circuit 10. be when between photovoltaic water pump motor overload or three phase windings during short circuit, this protective circuit is in time cut off the control signal of main circuit, thus protection main circuit and motor are not damaged.

(10), drive circuit 11. these circuit functions are that three-phase six road pulse-width signals that level shifting circuit is sent here are carried out power amplification, remove to drive six power components in the main circuit with enough power.

(11),main circuit 12. under the control of three-phase six road pulse-width signals that drive circuit sends, six power components of main circuit produce three-phase alternating currents, to drive the three phase electric machine of photovoltaic water pump.

(12),current sampling circuit 13. its effects are overload, overcurrent or the short-circuit signals that detect motor and main circuit, send photoelectric isolating circuit then to.

(13),photoelectric isolating circuit 14, the effect of this circuit is that main circuit and control circuit are separated, and avoids main circuit that control circuit produce is disturbed.

(14), manual control switch'scircuit 15. be provided with this circuit purpose be make things convenient for inverter produce and maintenance process in debugging and the manual intervention of photovoltaic water pump system.When the manual control switch connected on the photovoltaic water pump inverter, photovoltaic water pump was in unattended Automatic Control operating state.

The utlity model has following advantage:

One, compare with universal frequency converter, the utility model has realized driving with alternating current machine the MPPT maximum power point tracking and the frequency control Comprehensive Control of solar photovoltaic water pump system, and has realized the optimum Match of solar cell and photovoltaic water pump.MPPT maximum power point tracking circuit working stability, reliability height, given voltage adjusting range is wide, and it is convenient to set, and can extract maximum power from solar cell at any time.Two, the utility model provides beats dried protective circuit work sensitivity, can realize reliably beating of photovoltaic water pump done protection, avoids the anhydrous idle running of water pump and weares and teares, and has adapted to the long-term unattended operational environment of immersible pump.Three, the utility model cost is lower and efficient is higher.Efficient can reach 96-97%.It also has characteristics such as simple to operate, easy to maintenance.

Fig. 1 is solar cell output characteristic curve figure.

Fig. 2 is an outline drawing of the present utility model.

Fig. 3 is a circuit block diagram of the present utility model.

Fig. 4 is MPPT maximum power point tracking circuit theory diagrams of the present utility model.

Fig. 5 is the dried protective circuit schematic diagram of beating of the present utility model.

Describe embodiment of the present utility model in detail below in conjunction with accompanying drawing.

As shown in Figures 2 and 3, the utility model comprise housing 1, be contained inswitching power circuit 2 in the housing, PWM frequency conversion control circuit 4,protection control circuit 5, level shifting circuit 6, overheating protection circuit 7, under-voltage protectingcircuit 8, short circuit over-currentprotection circuit 10, drive circuit 11,main circuit 12,current sampling circuit 13,photoelectric isolating circuit 14, and manual control switch's circuit 15.The utility model also is provided with MPPT maximum powerpoint tracking circuit 3 and beats driedprotective circuit 9.

Described switching power circuit, PWM frequency conversion control circuit, under-voltage protecting circuit, short circuit over-current protection circuit, drive circuit, main circuit, current sampling circuit, photoelectric isolating circuit and manual control switch's circuit all adopt prior art, and are contained in the housing 1 by connector.

Described MPPT maximum powerpoint tracking circuit 3 as shown in Figure 4, it mainly is made up of operational amplifier A 1 (adopting 1/2LM358 in this example), resistance R 1, R2, R3, R4, R5 and capacitor C 1.Operational amplifier A 1 reverse input end joins with+5V reference voltage by R5, and input links to each other with the centre tap of potentiometer R2 by resistance R 4 in the same way.By resistance R 1, R3 and potentiometer R2 solar cell and main circuit both end voltage are sampled.To be input to the input in the same way of operational amplifier A 1 with the voltage signal of sunshine and load variations, the automatic adjusting of the PI proportional and integral controller of forming via operational amplifier A 1,resistance R 5, capacitor C 1, the voltage signal that operational amplifier output changed with sunshine.This signal is delivered to the PWM frequency conversion control circuit through resistance R 6.

Describedly beat driedprotective circuit 9 as shown in Figure 5; compriseoperational amplifier A 2, resistance R 7, R8, R9, R10, R11, R12, R13;capacitor C 2, E1; voltage-stabiliser tube Z1; diode D1, D2; transistor T 1, relay J (normally open contact J1, normally closed interlock J2), LED 1 and three beat and do protection probe H, M, L.In the foregoing circuit, coil one end of the end of R8 and relay J links to each other, and receives a road independently on the 12V power supply of Switching Power Supply output.Beating to do protects probe H to link to each other with the end of relay normally closed interlock J2 and an end of resistance R 7.Beating to do protects probe M to link to each other with the other end of relay normally closed interlock J2.Beat and do protection probe L and beat linking to each other of dried protective circuit publicly.Relay normally open contact J1 one end links to each other with the 12V power supply, and the other end links to each other with positive pole and theresistance R 13 of diode D2.LED 1 one ends link to each other with R13, and the other end links to each other with level shifting circuit publicly.Resistance R 7, R8, R9, R10, R11, voltage-stabiliser tube Z1,operational amplifier A 2 are formed voltage comparator.The end in the same way ofoperational amplifier A 2 links to each other with R11 with R9, and its backward end links to each other with R8 withR7.Capacitor C 2 and E1 parallel connection, wherein a termination is beaten and is done the public ground of protective circuit, the backward end of another termination operational amplifier.The output of operational amplifier links to each other through the base stage ofresistance R 12 with transistor T 1, and emitter links to each other with relay coil one end, its collector electrode with beat linking to each other of dried protective circuit publicly.Diode D1 is in parallel with relay coil.Reduce to when water level and beat to do protection probe M when following; the operational amplifier output low level; transistor T 1 conducting this moment, relay J coil electricity, its normally open contact J1 closure; the 12V high level is switched on; make the protection control circuit cut off three-phase six road pwm control signals through diode D2, main circuit and motor are quit work, realize beating dried protection purpose; meanwhile, beating dried protection indicator light LED1 is lighted.The negative pole of diode D2 links to each other with the control end of protection control circuit.

The annexation of above-mentioned each circuit as shown in Figure 2, overheating protection circuit 7 is serially connected with between solar cell array and the switching power circuit 2.Switching power circuit 2 and MPPT maximum powerpoint tracking circuit 3, PWM frequency conversion control circuit 4, beat circuit such as doingprotection 9 and link to each other, and provide 12V direct-current working volts for these circuit.The input of MPPT maximum powerpoint tracking circuit 3 links to each other with solar cell array,main circuit 12, and its output links to each other with PWM frequency conversion control circuit 4.PWM frequency conversion control circuit 4, under-voltage protecting circuit 8, the output of beating driedprotective circuit 9, short circuit over-currentprotection circuit 10 and manual control switch'scircuit 15 link to each other with the control end of protection control circuit 5.Six inputs of level shifting circuit 6 link to each other with six outputs ofprotection control circuit 5 respectively.Six road inputs of drive circuit 11 link to each other with six outputs of level shifting circuit 6 respectively.Six outputs of drive circuit 11 link to each other with the control end of six power components ofmain circuit 12 respectively.Three outputs of the three-phase alternating current of main circuit 11 link to each other with three phase winding exits of solar photovoltaic water pump motor respectively.The input ofsample circuit 13 links to each other withmain circuit 12, and its output links to each other with the input of photoelectric isolating circuit 14.The input of short circuit over-currentprotection circuit 10 links to each other with the output ofphotoelectric isolating circuit 14, and its output links to each other with drive circuit 11 withprotection control circuit 5 respectively.

Claims (3)

1. photovoltaic water pump inverter, comprise housing (1), switching power circuit (2), be contained in the PWM frequency conversion control circuit (4) in the housing, protection control circuit (5), level shifting circuit (6), overheating protection circuit (7), under-voltage protecting circuit (8), short circuit over-current protection circuit (10), drive circuit (11), main circuit (12), current sampling circuit (13), photoelectric isolating circuit (14) and manual control switch's circuit (15), it is characterized in that also being provided with MPPT maximum power point tracking circuit (3) and beat dried protective circuit (9), described overheating protection circuit (7) is serially connected with between solar cell array and the switching power circuit (2); The input of MPPT maximum power point tracking circuit (3) links to each other with main circuit (12) with solar cell, and output then links to each other with PWM frequency conversion control circuit (4); PWM frequency conversion control circuit (4), under-voltage protecting circuit (8), the output of beating dried protective circuit (9), short circuit over-current protection circuit (10) and manual control switch's circuit (15) all link to each other with the control end of protection control circuit; Current sampling circuit (13) input links to each other with main circuit (12); The input of level shifting circuit (6) links to each other with the output of protection control circuit (5), and its output links to each other with drive circuit (11); The input of main circuit (12) links to each other with the output of drive circuit (11), and its output links to each other with the motor windings of solar photovoltaic water pump; The input of current sampling circuit (13) links to each other with main circuit (12), and its output links to each other with photoelectric isolating circuit (14); The input of short circuit over-current protection circuit (10) links to each other with photoelectric isolating circuit (14), and its output links to each other with drive circuit (11) with protection control circuit (5) respectively; Switching power circuit (2) and MPPT maximum power point tracking circuit (3), PWM frequency conversion control circuit (4), protection control circuit (5), level shifting circuit (6), under-voltage protecting circuit (8), beat dried protective circuit (9), short circuit over-current protection circuit (10), drive circuit (11), main circuit (12), photoelectric isolating circuit (14) and manual control switch's circuit (15) and link to each other, and provide 12V direct-current working volts for these circuit.

2. photovoltaic water pump inverter according to claim 1, it is characterized in that described MPPT maximum power point tracking circuit (3) mainly is made up of operational amplifier A 1, resistance R 1, R2, R3, R4, R5, R6 and capacitor C 1, its input links to each other with main circuit (12) with solar cell respectively by dividing potential drop sampling resistor R1, R2, R3, and output then links to each other with PWM frequency conversion control circuit (4).

3. photovoltaic water pump inverter according to claim 1; it is characterized in that the described dried protective circuit (9) of beating comprises operational amplifier A 2; resistance R 7; R8; R9; R10; R11; R12; R13; capacitor C 2; E1; voltage-stabiliser tube Z1; diode D1; D2; transistor T 1; relay J (normally open contact J1; normally closed interlock J2); LED 1 and three beat and do protection probe H; M; L; wherein an end of resistance R 8 links to each other with coil one end of relay J; and join with one group of 12V out-put supply of switching power circuit (2); another group 12V out-put supply of the end of the normally open contact J1 of relay and switching power circuit (2) joins; its other end links to each other with the positive pole of diode D2; the negative pole of diode D2 links to each other with the control end of protection control circuit (5); resistance R 13 and LED 1 are connected between the positive pole and solar cell array negative pole of diode D2; beating to do protects probe H to link to each other with relay normally closed interlock J2 one end and resistance R 7 one ends; beating the other end of doing protection probe M and relay normally closed interlock J2 joins; beat and do protection probe L and beat joining of dried protective circuit (9) publicly, probe H; M; L places the top of photovoltaic water pump respectively; top and bottom.

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