Low-loss solar cell isolation protective circuit
Technical field
The utility model relates to the uninterrupted power supply (ups) Unity of band solar charging electric work function, relates in particular to a kind of low-loss solar cell isolation protective circuit.
Background technology
In the UPS product of band solar charging electric work function, solar cell need be isolated battery tension when output voltage is more weak to solar panel, prevent the anti-damage solar panel of irritating of battery tension.In the UPS product of existing band solar charging electric work function, when solar cell is lower than battery tension because of reasons such as illumination deficiency cause its output voltage, prevent that for reaching battery tension is through the counter purpose of damaging solar panel of irritating of battery charge impulse circuit; Schottky power diode D (referring to accompanying drawing 2) has connected in the solar recharging input circuit; The characteristic of utilizing diode reverse voltage to end is isolated the voltage and the solar panel of storage battery, but this diode (often reaching tens amperes) when charging current is big causes diode to produce bigger power loss (often reaching more than tens watts) owing to there is higher conduction voltage drop; Wasted valuable resource; Reduced the efficient of solar charger, simultaneously, for ensureing this diode ability operate as normal; Need be its external bigger radiator; The high volume of cost is big, and the power loss that diode produces has also caused the machine system temperature to rise, and has influence on system reliability.Above reason has restricted the miniaturization and the high efficiency of equipment, and higher temperature rise simultaneously has influence on the reliability of system.
Summary of the invention
The purpose of the utility model is the problems referred to above to the protective circuit existence of in the UPS product of existing band solar charging electric work function storage battery and solar panel being isolated; A kind of loss of the UPS of reduction solar charging battery input circuit is provided, improves the efficient and the low-loss solar cell isolation protective circuit that reduces the machine system temperature of charger.
The purpose of the utility model is achieved in that the utility model comprises control chip, switching circuit, chip protection circuit, chip power supply circuit; The input pin of said control chip, output pin are parallelly connected with switching circuit, and the input pin of control chip is connected with solar cell is anodal, and output pin is connected with a back grade charging circuit; One termination solar cell of said chip power supply circuit is anodal, the vcc pin of another termination control chip; The GND pin of one termination control chip of said chip protection circuit, another termination solar cell negative pole.
Preferably, said switching circuit is switching tube Q1, and the source electrode of switching tube Q1 is connected with the input pin of the positive pole of solar cell and control chip, and its drain electrode is connected with the output pin of back level charging circuit and control chip; Said control chip is the LTC4357 chip, and the signal output pin of control chip connects the grid of switching tube Q1; Said chip protection circuit is a diode, its anodal GND pin that connects control chip, and negative pole connects the negative pole of solar cell; Said chip power supply circuit is a resistance, is connected between the vcc pin of solar cell positive pole and control chip.Better, said switching tube Q1 is the N channel power MOS FET of low conducting internal resistance, between its source electrode and drain electrode, diode in the body is arranged.
The technique effect of the utility model is: compare through the anti-back flow circuit of series connection power schottky diode in charging circuit in the utility model and the prior art, have following advantage:
1. low-loss, efficient is high, can increase system efficiency, in the class product, have competitive advantage.
2. volume is little, need not additional cooler, has not only saved the radiator cost, has more saved valuable PCB space, is beneficial to the product miniaturization.
3. circuit is simple, and reliability is high.
Description of drawings
Fig. 1 is the electrical block diagram of the utility model embodiment;
Fig. 2 is existing solar cell anti-back flow circuit structural representation;
Embodiment
Referring to Fig. 1; Present embodiment low-loss solar cell isolation protective circuit comprises control chip U1, switching circuit, chip protection circuit, chip power supply circuit; Control chip U1 is the U1LTC4357 chip of Linear Techn Inc. (LinearTechnology Corporation); Switching circuit is switching tube Q1, and switching tube Q1 adopts the N channel power MOS FET of low conducting internal resistance, between its source electrode and drain electrode, diode in the body is arranged; Chip protection circuit is that diode D1 also claims chip protection diode D1, and chip power supply circuit is that resistance R 1 is also claimed chip power supply resistance R 1; The source electrode of switching tube Q1 is connected with the anodal PV+ of solar cell and the input pin in of control chip U1; Its drain electrode is connected with the output pin out of control chip U1 with back level charging circuit (the back level charging circuit in the present embodiment is the battery charge impulse circuit); Input pin in, the output pin out of control chip U1 are parallelly connected with switching circuit, and the signal output pin gate of control chip U1 connects the grid of switching tube Q1; The anodal PV+ of one termination solar cell of chip power supply resistance R 1, the vcc pin of another termination control chip U1; The GND pin of the termination control chip U1 of chip protection diode D1, another termination solar cell negative pole PV-.
The course of work and the principle of present embodiment are: under the illumination normal condition; Solar cell meeting output dc voltage; Operating current is provided for the Vcc of control chip U1; Simultaneously electric current can charge a battery with the battery charge impulse circuit by diode in switching tube Q1 body, when control chip U1 detects this charging and flows the forward voltage drop that in switching tube Q1 body, forms on the diode greater than 0.025V (that is: Vin>Vout 0.025V) through its input pin in pin and output pin out pin, and control chip U1 inside combination booster circuit; Export one: Vgate is greater than the high level signal of Vin 4.5V~15V (that is: Q1Vgs=4.5~15V); Driving switch pipe Q1 gets into conducting state fast, because switching tube Q1 selects the MOSFET (below the 10m Ω) of low conducting internal resistance for use, has realized the purpose of low-loss charging; Control chip U1 detects solar array voltage and battery tension (any moment in real time through its input pin in pin and output pin out pin; Battery tension can both feed back to the out pin of control chip U1 through the battery charge impulse circuit); When illumination is unusual; The voltage of solar cell output is less than the voltage of storage battery, and during the Yin of control chip U1<Vout0.025V, control chip U1 can think that solar array voltage is low excessively; The gate pin of control chip U1 is low level signal of output fast; Driving switch pipe Q1 gets into off state, thereby has blocked the path between the positive pole of PV+ and storage battery of solar cell, has realized preventing that battery tension from pouring in down a chimney the purpose to solar cell.Diode D1 among Fig. 1 plays protection control chip U1; When the solar cell PV+ utmost point; The reversal connection of the PV-utmost point is during to circuit shown in Figure 1; Diode D1 oppositely ends, and makes control chip U1 avoid causing the reverse voltage stress harm of its damage, the withstand voltage open circuit voltage that should be higher than solar cell of diode D1.
For more one going on foot the low-loss advantage of understanding the utility model, under identical condition of work, compare with Fig. 2 circuit in the face of Fig. 1 down.
Condition of work: 20 amperes of charging current mean values;
Component parameter: switching tube Q1 conducting internal resistance 7.5m Ω;
As shown in Figure 1, switching tube Q1 is 20 ampere-hours at charging current mean value, and its power consumption is WQ1=20A*20A*7.5m Ω=3W.
As shown in Figure 2, power schottky diode D is at charging current mean value 20 ampere-hours, and its power consumption is WD=20A*1V=20W.Be to be understood that in practical application, the forward voltage drop of power schottky diode and the relation of electric current, the power schottky diode when being 20A through average current, its pressure drop near 1V about.
Find relatively that through above under identical conducting current condition, the working loss of the embodiment circuit of Fig. 1 is obviously little a lot of than the working loss of Fig. 2 available circuit, has realized the purpose of low-loss charging.
More than be merely the preferred embodiment of the utility model; Be not thus the restriction the utility model claim; Can need suitably adjust circuit with certificate in the practical application; Every equivalent structure transformation that utilizes the utility model specification and accompanying drawing content to be done, or directly or indirectly be used in other relevant technical field, all in like manner be included within the scope of patent protection of the utility model.