CN101572427A - Battery power supply system based on high-efficiency big-current voltage booster - Google Patents

Abstract

A battery power supply system based on a high-efficiency big-current voltage booster comprises an input power supply; the battery power supply system further comprises a boosting branch and a digital control chip for controlling the make-and-break frequency of the MOS tube; the boosting branch comprises an MOS tube, an inductor, a diode and an energy storage capacitor; the input power supply is connected with one end of the inductor; the connection node at the other end of the inductor is connected with the drain electrode of the MOS tube and the diode at the same time; the diode is connected with the anode of the energy storage capacitor; the gate pole of the MOS tube is connected with the digital control output end of the digital control chip; the source of the MOS tube is connected with the cathode of the energy storage capacitor via a sampling resistor; the anode of the energy storage capacitor is connected with the output end of the power supply. The invention provides a battery power supply system based on the high-efficiency big-current voltage booster with small cubage, small power consumption, high efficiency and prolonged service life.

Description

Battery power supply system based on high-efficiency big-current voltage booster

Technical field

The invention belongs to a kind of battery power supply system, especially a kind of storage battery.

Background technology

Along with popularizing of storage battery, battery-driven application is more and more.The life-span of battery and three big factors have relation, the one, the quality problem of battery itself (prescription of pole plate and welding procedure), the 2nd, scientific and reasonable using method (the charging and discharging currents size and the degree of depth), the 3rd, the combo problem, preceding two of this three big factor all solves than being easier to basically, but the most difficult still the 3rd combo problem, this is the difficult problem that any battery producer all is difficult to solution all the time.

In fact also just so, the battery that the great majority series connection is used finally all is the phenomenon that one or two fails in advance to occur, seldom there are a plurality of batteries aging simultaneously, most batteries of decline in advance are exactly because the result that series connection is used, because the battery series connection uses the rapid variation of consistency that the later stage can make battery, it is mainly reflected in individual cell because of over-discharge can (this is unavoidable forever) sulfation in the middle of series circuit, and individual cell when charging because of regular overcharging (this also is unavoidable forever in the middle of series circuit) dehydration until filling drum.

So, series circuit can cause because of the consistency problem of battery the part battery because of overdischarge, overcharge, owe charging and damage in advance, change series connection into consistency problem that parallel connection can be ignored battery fully, afterwards terminal voltage is all the same because of its parallel connection, the phenomenon of overdischarge can never occur, overcharge, owing to charge can average out automatically according to the internal resistance of each battery during work.But voltage ratio series connection in rear end in parallel is low, so also will boost and could use with stepup transformer in application.

At above problem, the domestic similarly stepup transformer of also once developing.Volume of transformer is excessive, shortcomings such as efficient is low excessively, poor reliability do not solve root problem but adopt, and can not get extensive use.High efficient and reliable of the present invention, volume are small and exquisite, have realized this function fully.

Summary of the invention

The deficiency that existing stepup transformer volume is big, no-load power consumption is too high, efficient is low in order to overcome, useful life is short the invention provides the battery power supply system based on high-efficiency big-current voltage booster that a kind of volume is small and exquisite, low in energy consumption, efficient is high, increase the service life.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of battery power supply system based on high-efficiency big-current voltage booster, comprise the input power supply, described battery power supply system also comprises the branch road and in order to the digital control chip of break-make frequency of control metal-oxide-semiconductor of boosting, the described branch road that boosts comprises metal-oxide-semiconductor, inductance, diode and storage capacitor, the input power supply connects an end of described inductance, the connected node of the described inductance other end is connected with diode with the drain electrode of metal-oxide-semiconductor simultaneously, and described diode is connected with the positive pole of described storage capacitor; The gate pole of described metal-oxide-semiconductor is connected with the digital control output of described digital control chip, and the source electrode of described metal-oxide-semiconductor is connected with the negative pole of described storage capacitor by a sample resistance; The positive pole of described storage capacitor is connected with power output end.

As outstanding a kind of scheme: the connected node ground connection of described sample resistance and described storage capacitor.

Further, described digital control output is the PWM control end.

The source electrode of described metal-oxide-semiconductor also is connected with the voltage feedback signal end of described digital control chip by additional resistance.The resistance of sampling resistor is less, and described voltage feedback signal end is in order to detect the voltage that bears on the sample resistance.

Described storage capacitor is in parallel with idle capacity.

Further again, the digital control output of described digital control chip has two, and two digital control output ends are connected with the gate pole of the metal-oxide-semiconductor of the branch road that boosts respectively.

Technical conceive of the present invention is: efficient heavy DC booster circuit is referred in the storage battery power supply system, boost with respect to transformer of the prior art, has the advantage that volume is little, power consumption is little, efficient is high, storage battery parallel power supply can increase the service life greatly, has good practicality.

The boost converter perhaps is Step-up converter, is a kind of switch DC booster circuit, and it can be that output voltage is than input voltage height.Basic circuit diagram is seen Fig. 1.

Suppose that switch (triode or metal-oxide-semiconductor) has disconnected for a long time, all elements all are in perfect condition, and capacitance voltage equals input voltage.To divide the charging and two parts of discharging that this circuit is described below.

Charging process: in charging process, switch closure (triode or metal-oxide-semiconductor conducting), equivalent electric circuit such as Fig. 2, switch (triode or metal-oxide-semiconductor) is located to replace with lead.At this moment, input voltage flows through inductance.Diode prevents that electric capacity from discharging over the ground.Because input is a direct current, so the electric current on the inductance increases so that certain ratio is linear, this ratio is relevant with the inductance size.Along with inductive current increases, some energy have been stored in the inductance.

Discharge process: as Fig. 3, this is the equivalent electric circuit when switch disconnects (triode or metal-oxide-semiconductor end).When switch disconnected (triode or metal-oxide-semiconductor by), because the electric current retention performance of inductance, the electric current of the inductance of flowing through can not become 0 at once, but the value when being finished by charging slowly becomes 0.And original circuit has disconnected, so inductance can only discharge by novel circuit, promptly inductance begins to the electric capacity charging, and the electric capacity both end voltage raises, and this moment, voltage was higher than input voltage, and boosting finishes.

As Fig. 4, the sawtooth waveforms that inductive current (Inductor current) forms at charge and discharge process, the process of boosting is exactly the energy transfer process of an inductance in fact.During charging, inductance absorbs energy, and inductance is emitted energy during discharge.If capacitance is enough big, just can in discharge process, keep a lasting electric current at output so.If the process of this break-make constantly repeats, just can obtain being higher than the voltage of input voltage at the electric capacity two ends.

Beneficial effect of the present invention mainly shows: 1, volume is small and exquisite, power consumption is little, efficient is high, increase the service life; 2, practicality is good.

Description of drawings

Fig. 1 is the citation form schematic diagram of BOOST circuit;

Fig. 2 is the charging process equivalent circuit diagram;

Fig. 3 is the discharge process equivalent circuit diagram;

Fig. 4 is the current waveform schematic diagram on the inductance;

Fig. 5 is the circuit diagram of the high-efficiency big-current voltage booster of battery power supply system.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.

With reference to Fig. 5, a kind of battery power supply system based on high-efficiency big-current voltage booster, comprise the input power supply, described battery power supply system also comprises the branch road and in order to the digital control chip of break-make frequency of control metal-oxide-semiconductor of boosting, the described branch road that boosts comprises metal-oxide-semiconductor, inductance, diode and storage capacitor, the input power supply connects an end of described inductance, and the connected node of the described inductance other end is connected with diode with the drain electrode of metal-oxide-semiconductor simultaneously, and described diode is connected with the positive pole of described storage capacitor; The gate pole of described metal-oxide-semiconductor is connected with the digital control output of described digital control chip, and the source electrode of described metal-oxide-semiconductor is connected with the negative pole of described storage capacitor; The positive pole of described storage capacitor is connected with power output end.

The connected node ground connection of described sample resistance and described storage capacitor.Described digital control output is the PWM control end.The source electrode of described metal-oxide-semiconductor also is connected with the voltage feedback signal end of described digital control chip by additional resistance.Described storage capacitor is in parallel with idle capacity.

The digital control output of described digital control chip has two, and two digital control output ends are connected with the gate pole of the metal-oxide-semiconductor of the branch road that boosts respectively.

In like manner, described voltage feedback signal end also has two, and the additional resistance with the branch road that boosts is connected respectively.

First branch road that boosts comprises the first metal-oxide-semiconductor Q1, first inductance L 1, the first diode D1, the first storage capacitor C13, the first idle capacity C23, first resistance R 16 and second resistance R 12; Second branch road that boosts comprises the second metal-oxide-semiconductor Q2, second inductance L 2, the second diode D2 and the second storage capacitor C14, the second idle capacity C34, the 3rd resistance R 17 and the 4th resistance R 13;

24 pins and 13 pins of digital control chip are the PWM control end.23 pins and 14 pins of digital control chip are the SENSE pin, are the voltage feedback signal end, and resistance R 12 is connected with pin 23, resistance R 13 is connected with pin 14 is in order to gather voltage signal, and increases reliability.

The design process of this example battery power supply system is:

(1), determine input, output voltage, output current: the present invention can operate as normal under the input voltage of DC4V-DC36V.The condition of work of considering practical application is: input 12V, output 48V/10A.Can operate as normal for considering under the input voltage of 10.5-13.5V, so be limited to 10V under the input voltage during design.

(2), the setting of operating frequency: operating frequency of the present invention can be worked in the 75KHZ-500KHZ scope, and different operating frequencies is by the outer meeting resistance decision of chip respective pins, in order to reduce the difficulty of PCB layout, so frequency is selected for use about 300K.

Require to calculate the main devices parameter according to reality: the Boost booster circuit can be operated in discontinuous current mode of operation (DCM) and electric current continuous operation mode (CCM).The CCM mode of operation is fit to high-power output circuit, considers that load reaches 10% when above, and inductive current need keep continuous state, therefore, carries out specificity analysis by the CCM mode of operation.

By BOOST booster circuit basic waveform as can be known: during ton, switching tube S is a conducting state, and diode D is in cut-off state, and the electric current of the inductance L of flowing through and switching tube increases gradually; The voltage at inductance L two ends is Vi, considers the conduction voltage drop Vs of switching tube S drain electrode to common port, is Vi-Vs.Electric current by L during ton increases part Δ I _LonBe (1):

$\mathrm{\Δ}{I}_{\mathrm{Lon}}=\frac{(\mathrm{Vi}-\mathrm{Vs})\mathrm{ton}}{L}---\left(1\right)$

In the formula: the pressure drop sum on pressure drop when Vs is the switching tube conducting and the current sampling resistor Rs, about 0.6～0.9V.

During toff, switching tube S ends, diode D is in conducting state, the energy that is stored in the inductance L offers output, the electric current of the inductance L of flowing through and diode D is in the minimizing state, and the forward voltage of establishing diode D is Vf, during toff, the voltage at inductance L two ends is Vo+Vf-Vi, the minimizing part Δ I of electric current _LoffSatisfy formula (2).

${\mathrm{\ΔI}}_{\mathrm{Loff}}=\frac{(\mathrm{Vo}+\mathrm{Vf}-\mathrm{Vi})\mathrm{toff}}{L}---\left(2\right)$

In the formula: Vf is the rectifier diode forward voltage drop, the about 0.8V of fast recovery diode, the about 0.5V of Schottky diode.

Under the circuit stable state, promptly from electric current continuously the back when maximum is exported, Δ I _Lon=Δ I _LoffCan get by formula (1) and (2)

$\frac{\mathrm{toff}}{\mathrm{ton}}=\frac{\mathrm{Vi}-\mathrm{Vs}}{\mathrm{Vo}+\mathrm{Vf}-\mathrm{Vi}}$

Because of duty ratio D=t _OnSo/T is maximum duty cycle $D_{\max }=\frac{\mathrm{Vo}+\mathrm{Vf}-\mathrm{Vi}}{\mathrm{Vo}=\mathrm{Vf}-\mathrm{Vs}}\≈\frac{\mathrm{Vo}-\mathrm{Vi}}{\mathrm{Vo}}$

So, according to actual operating conditions:

$D\max =\frac{48+0.5-10}{48+0.5-0.5}=80\%$

$D\min =\frac{48+0.5-36}{48+0.5}=25.8\%$

This circuit working is (CCM pattern) under the 300KHZ situation,

$t_{\mathrm{on}\left(\min \right)}=\frac{1}{f}\·\frac{\mathrm{Vo}+\mathrm{Vf}-\mathrm{Vin}}{\mathrm{Vo}+\mathrm{Vf}}=\frac{1}{300\mathrm{KHZ}}\·\frac{48+0.5-36}{48+0.5}=859\mathrm{nS}$

The maximum input current of stepup transformer is:

$I_{\mathrm{IN}\left(\max \right)}=\frac{\mathrm{Io}\left(\max \right)}{1-D\max }=\frac{10}{1-0.8}=50A$

Ripple according to 40%, the average current of the inductance is as follows:

$I_{\mathrm{IN}\left(\mathrm{PK}\right)}=\frac{1}{n}\·(1-\frac{x}{2})\·\frac{\mathrm{Io}\max }{1-D\max }=30A$

Ripple current on the inductance is:

${\mathrm{\ΔI}}_L=\frac{x}{n}\·\frac{\mathrm{Io}\left(\max \right)}{1-D\max }=10A$

The calculating of inductance value

$L=\frac{\mathrm{Vin}\left(\min \right)}{\mathrm{\ΔIL}\·f}\·D\max =2.7\mathrm{uH}$

If the limiting current of work is for surpassing 30% of maximum current, then the limiting current value is:

I _o(CL)＝1.3·I _o(max)＝13A

The saturation current of inductance is:

$I_{L\left(\mathrm{SAT}\right)}\≥\frac{1}{n}\·(1+\frac{x}{2})\·\frac{1.3\·\mathrm{Io}\left(\max \right)}{1-D\max }=39A$

Therefore, will be during inductance customized according to above parameter.Type selecting to metal-oxide-semiconductor is then selected VGS=4V for use,

RDS=13m Ω, the metal-oxide-semiconductor of the STP75NF75 of VDS=75V.

Electric current on the sample resistance is:

$I_{R\left(\mathrm{SENSE}\right)}=\frac{1}{n}\·(1+\frac{x}{2})\·\frac{1.3\·\mathrm{Io}\left(\max \right)}{1-D\max }=39A$

There is the comparative voltage of a 73mV control chip inside, so the resistance of sample resistance is as follows:

$\mathrm{Rsense}=\frac{73}{39}=1.87\mathrm{m\Ω}$

Therefore, the concrete parameter of present embodiment is: the inductance value of L1 and L2 is: 2.7uH; The sample resistance of digital control chip is: 1.87m Ω; The capacitance of the first storage capacitor C13, the second storage capacitor C14, the first idle capacity C23 and the second idle capacity C34: 10uF; The resistance of resistance R 16 and R17: 2m Ω; The resistance of resistance R 12 and R13: 10 Ω.

The low-tension supply VIN of this example (input) voltage is 5～36v, and by the duty cycle adjustment of digital control chip, its output voltage VO UT is 48V.

Claims (6)

1, a kind of battery power supply system based on high-efficiency big-current voltage booster, comprise the input power supply, it is characterized in that: described battery power supply system also comprises the branch road and in order to the digital control chip of control metal-oxide-semiconductor break-make frequency of boosting, the described branch road that boosts comprises metal-oxide-semiconductor, inductance, diode and storage capacitor, the input power supply connects an end of described inductance, the connected node of the described inductance other end is connected with diode with the drain electrode of metal-oxide-semiconductor simultaneously, and described diode is connected with the positive pole of described storage capacitor;

The gate pole of described metal-oxide-semiconductor is connected with the digital control output of described digital control chip, and the source electrode of described metal-oxide-semiconductor is connected with the negative pole of described storage capacitor by a sample resistance;

The positive pole of described storage capacitor is connected with power output end.

2, the battery power supply system based on high-efficiency big-current voltage booster as claimed in claim 1 is characterized in that: the connected node ground connection of described sample resistance and described storage capacitor.

3, the battery power supply system based on high-efficiency big-current voltage booster as claimed in claim 1 or 2 is characterized in that: described digital control output is the PWM control end.

4, the battery power supply system based on high-efficiency big-current voltage booster as claimed in claim 3 is characterized in that: the source electrode of described metal-oxide-semiconductor also is connected with the voltage feedback signal end of described digital control chip by additional resistance.

5, the battery power supply system based on high-efficiency big-current voltage booster as claimed in claim 3, it is characterized in that: described storage capacitor is in parallel with idle capacity.

6, the battery power supply system based on high-efficiency big-current voltage booster as claimed in claim 1 or 2, it is characterized in that: the digital control output of described digital control chip has two, and two digital control output ends are connected with the gate pole of the metal-oxide-semiconductor of the branch road that boosts respectively.

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