The content of the invention
For above-mentioned technical problem, the object of the present invention is to provide a kind of photovoltaic bypass diodes rational in infrastructure.
Realize that technical scheme is as follows：
A kind of photovoltaic bypass diode, including first comparator, the second comparator and door, buffer, the first power MOSPipe, the second power MOS pipe, oscillator, capacitance C,
The output terminal of the first comparator is connected with the input terminal with door, the output terminal of the second comparator with doorAnother input terminal connection, is connected, the output terminal of buffer and the first power MOS pipe with the output terminal of door and the input terminal of bufferGrid connection, be connected with parasitic diode between the drain electrode of the first power MOS pipe and source electrode；The drain electrode of first power MOS pipeIt is connected with the inverting input of the second comparator,
And for capacitance C chargings and the charge pump of pressure drop on parasitic diode is improved, output terminal and the electricity of the oscillatorThe input terminal connection of lotus pump, the output terminal of charge pump and capacitance C, first comparator in-phase input end and connect,
The source electrode of second power MOS pipe and oscillator, charge pump simultaneously connect, and the drain electrode of the second power MOS pipe is photovoltaic bypassThe cathode of diode,
The grid of second power MOS pipe is sequentially connected the power input of oscillator, the power input of charge pump, capacitanceC one end, first comparator power input, with the power input of door, the power input of the second comparator, bufferPower input, the source electrode of the first power MOS pipe form the anode of photovoltaic bypass diode after connecting.
The in-phase input end of the first comparator is connected with by resistance R1, resistance R2 and connects the resitstance voltage divider formed,Between the in-phase input end connection of first comparator and resistance R1, resistance R2, the output terminal of the resistance R1 other ends and charge pump connectsIt connects.
Using above-mentioned technical solution, match somebody with somebody by using charge pump, two comparators, with door, two power MOS pipesIt closes, the conduction voltage drop for making photovoltaic bypass diode is low, and reverse leakage current is smaller.
Specific embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present inventionAttached drawing, the technical solution of the embodiment of the present invention is clearly and completely described.Obviously, described embodiment is this hairBright part of the embodiment, instead of all the embodiments.Based on described the embodiment of the present invention, ordinary skillPersonnel's all other embodiments obtained on the premise of without creative work, belong to the scope of protection of the invention.
As shown in Figure 1, a kind of photovoltaic bypass diode, including first comparator 1, the second comparator 2 and door 3, buffer4th, the first power MOS pipe 5, the second power MOS pipe 6, oscillator 7, capacitance C, the output terminal of first comparator with it is the one of door defeatedEnter end connection, the output terminal of the second comparator is connected with another input terminal with door, the input with the output terminal and buffer of doorEnd connection, the output terminal of buffer is connected with the grid of the first power MOS pipe, between the drain electrode of the first power MOS pipe and source electrodeIt is connected with parasitic diode 8；The drain electrode of first power MOS pipe is connected with the inverting input of the second comparator and is capacitance CIt charges and improves the charge pump 9 of pressure drop on parasitic diode, the output terminal of oscillator and the input terminal of charge pump connect, charge pumpOutput terminal and capacitance C, first comparator in-phase input end and connect, source electrode and oscillator, the charge pump of the second power MOS pipeAnd connect, the drain electrode of the second power MOS pipe is the cathode of photovoltaic bypass diode.
The grid of second power MOS pipe successively and connects the power input of oscillator, the power input of charge pump, capacitanceC one end, first comparator power input, with the power input of door, the power input of the second comparator, bufferPower input, the source electrode of the first power MOS pipe form the anode of photovoltaic bypass diode after connecting.The same phase of first comparatorInput terminal is connected with by resistance R1, resistance R2 and connects the resitstance voltage divider formed, the connection of the in-phase input end of first comparator withBetween resistance R1, resistance R2, the output terminal connection of the resistance R1 other ends and charge pump.
This photovoltaic bypass diode structure is as shown in Fig. 1 block diagrams.First power MOS pipe M1 is main switch element, parasiticDiode D short circuits undertake important function between the source electrode of the first power MOS pipe M1 and drain electrode when circuit works.
Boosting part, it (is charged to VDD including charge pump to capacitor C；VDD is supply voltage, is supplied to other partsElectricity, while improve the pressure drop on parasitic diode D) and oscillator (having source crystal oscillator).The effect of second power MOS pipe M2 is protectionOscillator, the oscillator are usually realized with active low voltage transistor.For this purpose, two pole of parasitic intrinsic of the first power MOS pipe M1The conduction threshold (usually in 300-400mV or so) of pipe must be bigger than the second power MOS pipe M2.
First comparator Comp1 monitors two threshold voltage VDD；Second comparator Comp2 and the first power MOS pipe M1 phasesEven, change in polarity is monitored.
Buffer provides driving voltage to the grid of the first power MOS pipe M1.It is needed in common DC/DC boost convertersInductance, in this product, we eliminate inductance, employ simpler standard IC integrated technologies.In addition, first comparatorThe switch of Comp1 control circuits, and first comparator Compl can accurately set threshold voltage (passing through resitstance voltage divider), andIt can be adjusted according to the minimum conduction threshold of the first power MOS pipe M1.
During work, when solar panel works normally, the voltage between the drain electrode of the first power MOS pipe M1 and source electrodeFor just, the first power MOS pipe M1 keeps cut-off state, at this moment assistant drive system does not also work.Such case is as shown in Figure 2 a.
If connected to the solar panel of power MOS pipe is a part of shielded, then the leakage of the first power MOS pipe M1Voltage reversal between pole and source electrode, signal become negative, because the electric current that generates of not shielded solar panel is from parasitic two polesThe cathode of pipe D flows to anode.Once the second power MOS pipe M2 is turned on, the voltage drop on parasitic diode D can be by charge pump profitWith such case annotates voltage value as shown in Fig. 2 .b, in left side, and the electric current from other solar panels flows through parasitic diodeD。
After several cycle oscillators, capacitor C is charged to voltage VDD needed for buffer, with enough drivesDynamic voltage turns on M1, to minimize drain source resistance --- Rds, on.As shown in Fig. 2 .b, right side annotates such caseVoltage value.In this case, most of electric current is flowed through from the first power MOS pipe M1.
Certainly, due to inevitable current loss, the charge on capacitance C must periodically recover.Entire driving systemSystem can be designed to make the charging time needed for capacitance C than the first power MOS pipe M1 ON time much less (such as<10%).In fact, when the voltage on capacitance C increases to certain threshold value (for example, could be provided as 5V), pass through detection theOne comparator Comp1, can turn on M1.In turn, (can be when the voltage at capacitance C both ends is reduced to relatively low threshold value4.5V), the first power MOS pipe M1 ends, to recover the charge of capacitor C.When shade is removed, the second comparatorComp2 detects reversed polarity condition, and making the first power MOS pipe M1 cut-offs, (the second power MOS pipe M2 is also ended and chargeIt pumps disabled).The logical produc of the signal from first comparator Comp1 and the second comparator Comp2 is performed with door so that onlyAt least one comparator output is wanted for 0 first power MOS pipe M1 can just to end.