CN1047944A - Switch capacitor isolated dc transducer - Google Patents

Abstract

The present invention relates to a kind of switch capacitor isolated DC transducer.It is characterized in that providing different pulse control signals for each switching tube, make the conducting or end when different conditions of each switching tube, and change the series and parallel mode of connection of capacitor group with this, realize the step-down working method of capacitor group serial connection charge, parallel discharge, and the working method of boosting of charged in parallel, Shen connection discharge.The present invention adopts switching tube and capacitance energy storage element, has changed the converter type DC converter of always prolonging usefulness for a long time, has cancelled AC transformer.

Description

Switch capacitor isolated DC transducer

The present invention relates to the device that a kind of direct current power input is transformed to direct current power output.More particularly, be a kind of switch capacitor isolated DC transducer that is used for DC converting.

In the prior art, the concrete working method of DC converter (DC-DC) conversion has a variety of, and is well-known with regard to its operation principle, and electric component pressure type buck converter and converter type conversion (inverter) are arranged.

Above-mentioned electric component pressure type buck converter operation principle is seen shown in the accompanying drawing 1.Output voltage V o=RLVi/(R1+RL), this mode major defect is:

1, output voltage V o is not a fixed value, but changes with the variation of load RL.

2, on its minute piezoelectricity group RJ R1Vi is always arranged ²/ (R1+RL) ²Power loss, so conversion efficiency is low.

Above-mentioned converter type conversion operation principle block diagram as shown in Figure 2.Utilize inverter that DC power supply is converted to interchange,, by current rectifying and wave filtering circuit the alternating current of transformer output rectification again is converted to direct current again through the electromagnetic induction element transformer.There is following obvious weak point in this mode:

1, intermediate link is many, components and parts line construction complexity, and exist indispensable AC transformer, therefore, whole device volume is big and heavy, cost is high, design difficulty is big.

2, owing to the process multiple conversions, so power consumption is big, the complete machine inefficiency.

In a word, DC converter of the prior art is not all escaped and is adopted inversion transformation technique and adopt transformer.

The objective of the invention is to avoid the deficiencies in the prior art part, a kind of DC converter that need not adopt inverter and AC transformer is provided.Utilize switching tube switching under the high frequency state, change the wiring of capacitor group, the capacitor group is discharged and recharged under the series, parallel mode respectively, thereby reach the purpose that the direct current power input directly is converted to direct current power output.

The objective of the invention is to be achieved through the following technical solutions.

The present invention mainly is made up of switching tube and capacity cell.

Feature of the present invention is:

A, described converter are made up of high pressure end line, low pressure end line and charging and discharging circuit.

B, described charging and discharging circuit by the capacitor group of forming by several capacitors, be connected high voltage control pipe between high pressure end line and the capacitor group, be connected low voltage control pipe between low pressure end line and the capacitor group, be connected the separating tube between each electric capacity of capacitor group and be connected in the capacitor group connecting to neutral pipe between each electric capacity and low-pressure end zero line and form.

The control end of c, described high voltage control pipe, low voltage control pipe, separating tube and connecting to neutral pipe is accepted pulse control signal respectively, alternately changes in conducting with under operating state with identical frequency.And, the conducting of described high voltage control pipe, separating tube and connecting to neutral pipe, low voltage control pipe and opposite by operating state.

The present invention is divided into each switching tube with the control impuls generating unit, just the control end of high voltage control pipe, low voltage control pipe, separating tube and connecting to neutral pipe provides same frequency respectively but the pulse control signal of out of phase, make the conducting or end under different time states of each switching tube, and with the frequency of pulse control signal in conducting, alternately conversion under operating state.Change the series and parallel working method of capacitor group with this, realize capacitor group serial connection charge, the step-down working method of parallel discharge, and charged in parallel, the working method of boosting of discharged in series.

Purpose of the present invention can also be achieved through the following technical solutions.

Charging and discharging circuit described in the present invention is made up of two parts.Described two parts charging and discharging circuit has identical circuit structure, but in two parts loop, interior at one time conducting of each corresponding switching tube or the operating state of ending are opposite, two loops discharge and recharge in time with complementing one another, like this, just, can in load, obtain the less discharging current of continuous ripple.

The present invention compares prior art and has following advantage.

The present invention adopts switching tube and capacitance energy storage element, has changed the converter type DC converter of always prolonging usefulness for a long time, has cancelled AC transformer.Thereby, great simplification has been arranged on circuit structure, cost reduces greatly, and operating efficiency is improved, and machine loss only is switching tube on-state loss and leaky condenser loss.Owing to adopt the capacitance energy storage element, the Peak Operating Voltage that makes switching tube only is to input or output crest voltage, because the partition effect of switching tube, and the capacitance energy storage transition, make the complete machine interference free performance improve greatly than the contravariant converter.Under the break-make frequency of switching tube allowed, operating frequency was high more, and the energy storage capacitor capacitance is more little, and the ripple of output voltage is also more little.Under the situation that switching tube self-condition such as power, drop-out voltage, switching frequency etc. allow, transmission capacity of the present invention can reach sizable numerical value, and, capacity and capacitor C value are irrelevant, can be widely used in D.C. regulated power supply, dc voltage conversion, strong current generator and arc welding equipment etc.

Fig. 1 is an electric component pressure type buck converter fundamental diagram in the prior art.

Fig. 2 is a converter type converter operation principle block diagram in the prior art.

Fig. 3 is an electrical block diagram of the present invention.

Fig. 4 is that the present invention is as the buck converter principle schematic.

Fig. 5 is that the present invention is as the booster converter principle schematic.

Fig. 6 adopts the principle schematic of complementary charging and discharging circuit for the present invention.

Number in the figure: 1,2, the high pressure end line, 3,4, the low pressure end line, RD switching tube on-state electricity group.

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

Embodiment 1:

Referring to Fig. 4, insert power supply Vi in 1,2 in high pressure end line, ri is a group in it, load RL connects 3,4 in low pressure end line, becomes buck converter.Because the pulse control signal that acts on switching tube Q end that is provided makes high voltage control pipe TH1, TH2, separating tube TG1, TG2 ... TGn-1 and low voltage control pipe TL1, TL2 ... TLn, connecting to neutral pipe To1, To2 ... Ton is opposite with the operating state of ending in the conducting of synchronization, therefore, as high voltage control pipe TH1, during the TH2 conducting, separating tube TG1, TG2 ... the TGn-1 conducting, connecting to neutral pipe To1, To2 ... Ton and low-voltage tube TL1, TL2 ... TLn all ends, capacitor group C1, C2 ... Cn becomes and is connected in series, and accept power supply Vi and charge, at this moment, charge circuit and load cut off, charge circuit equivalent electric group Ri=ri+(n+1) RD, equivalent capacity Ci=C/n, its charge constant τ i=RiCi, the pulse duration of the pulse control signal that is provided guarantees that each electric capacity has enough charging intervals, to be full of electricity, therefore, when charging process finished, the charging voltage on each capacitor C was Vi/n.When pulse control signal generation saltus step, high voltage control pipe TH1, TH2 transfer to and ending, separating tube TG1, TG2 ... TGn-1 also ends, connecting to neutral pipe To1, To2 ... Ton and low-voltage tube TL1, TL2 ... the equal conducting of TLn, each capacitor C 1, C2 in the capacitor group ... Cn then become is connected in parallel, and to load RL discharge, at this moment, discharge loop and power supply cut off.Discharge loop equivalent electric group Ro=RL+2RD/n, equivalent capacity Co=nC, its discharge time constant τ o=RoCo, the discharge process starting voltage is Vi/n.In the discharge process, the terminal voltage Uco=(1/n of equivalent capacity Co) Vie ^{-t/ τ o}, establishing the discharge process pulse duration is k τ o, (wherein k is the constant greater than zero), and then, the voltage effective value of equivalent capacitor C o output is in the discharge process: Vco= $\sqrt{(1/k{\&CenterDot;\mathrm{\&tau;}}_0){\&Integral;}_0^{k{\&CenterDot;\mathrm{\&tau;}}_0}{\mathrm{<figure-callout\; id="2"\; label="uco"\; filenames="901038725\_DRIMG5.png"\; state="\{\{state\}\}">uco</figure-callout>}}^2\&CenterDot;\mathrm{dt}}$ ＝（1/n）·Vi· $\sqrt{{\mathrm{(1\; -\; e}}^{\mathrm{－2\; k}}\mathrm{)\; /\; 2\; k}}$ Because RL

(2/n) RD.So Vi converter output voltage V o=Vco=(1/n) $\sqrt{{\mathrm{(1\; -\; e}}^{\mathrm{－2\; k}}\mathrm{)\; /\; 2\; k}}$ , realize decompression transformation.Wherein, $\sqrt{{\mathrm{(1\; -\; e}}^{\mathrm{－2\; k}}\mathrm{)\; /\; 2\; k}}$ Be transmission coefficient.

By following formula as seen, the number n of electric capacity is certain in the capacitor group, and the size of transmission coefficient is decided by the k value, also, is decided by the discharge process pulse duration.And the size of k value and transmission coefficient is inversely proportional to.

Arranged satisfying the capacitor group one enough charging intervals, under the prerequisite that is full of electricity, the adjustment of k value has dual mode, includes the frequency f of adjusting control impuls, or the control impuls duty ratio of adjusting discharge process.

Embodiment 2:

Referring to Fig. 5, different is with embodiment 1 described buck converter, and in 1, the 2 indirect loads of high pressure end line, power supply Vi connects 3,4 in low pressure end line, and ri is a group in it.Under the effect of pulse control signal, power source charges is accepted in the parallel connection of capacitor group, and discharges to load RL under series connection.Charge circuit equivalent electric group Ri=ri+2RD/n, equivalent capacity Ci=nC, charge constant τ i=RiCi, discharge loop equivalent electric group Ro=RL+(n+1) RD, equivalent capacity Co=C/n, discharge time constant τ o=RoCo, the pulse control signal that requires to be provided can guarantee that the capacitor group has enough charging intervals, make its charging process reach stable state, like this, discharge inception voltage is nVi.Can draw booster converter output voltage V o=nVi equally according to charge-discharge principle $\sqrt{{\mathrm{(1\; -\; e}}^{\mathrm{－2\; k}}\mathrm{)\; /\; 2\; k}}$ 。Identical with the buck converter principle, its transmission coefficient $\sqrt{{\mathrm{(1\; -\; e}}^{\mathrm{－2\; k}}\mathrm{)\; /\; 2\; k}}$ Also can pass through to adjust the control impuls frequency f, or the control impuls width duty of regulating discharge process is regulated recently.

Embodiment 3:

Referring to Fig. 6, adopt the converter of complementary charging and discharging circuit.

In embodiment 1,2 described converters, owing to adopt single charging and discharging circuit, therefore, what draw on load RL is a voltage signal that is interrupted.In the present embodiment, charging and discharging circuit is made up of charging and discharging circuit I and charging and discharging circuit II two parts, described two parts charging and discharging circuit has identical circuit structure, and, in loop I and loop II two parts circuit, interior at one time conducting of each corresponding switching tube or the operating state of ending are opposite, and two loop I, II discharge and recharge with complementing one another in time, like this, on load RL, can draw a continuous discharging current.

In the present embodiment, each switching tube can be selected power MOSFET tube, wherein, high voltage control pipe T H1, TH2, TH1 ', TH2 ' are IRF455, and low voltage control pipe TL1, TL2, TL1 ', TL2 ', separating tube TG1 ', TG1 and connecting to neutral pipe To1 ', To2 ', To1 ', To2 adopt 4N18.Even piezoelectricity group RG, RS, RG ', RS ' provide pulse control signal for separating tube, also press for each capacitor C 1, C2, C1 ', C2 ' in the capacitor group provide even.When 1,2 in high pressure end line inserts 300 volts of direct voltages, selecting capacitor C1, C2, C1 ', C2 ' is the noninductive electric capacity of 2 μ F/200v, RG ', RG are 14M Ω/1W, RS ', RS are 1M Ω/1W, draw as calculated, and the output voltage that its low pressure end line is 3,4 is 100 volts of burning voltages, maximum operating frequency is designed to 1MHZ, maximum output current 25A allows supply voltage Vi fluctuation range ± 10%, and maximum load power can be 3KW.

Because big electric current, high voltage, high-frequency switching tube (also being power electronic element) continue to bring out, existing at present power MOSFET, maximum current is 60A, maximum operating voltage 1000V; Bi-MOSFET Imax is 200A, and Vmax reaches 1000V; GTO Imax reaches 4500A, and Vmax reaches 5000V; MOS control thyristor MCT through-put power has reached 10VA, if said elements is used for the present invention, can design voltage of transformation grade height, electric current is big, through-put power applies to electric power system greatly DC converter, also will provide more service condition for direct current transportation in the electric power system.

Claims (2)

1, a kind of switch capacitor isolated DC transducer that is used for DC converting is made up of switching tube and capacity cell, it is characterized in that:

A, described converter are made up of high pressure end line, low pressure end line and charging and discharging circuit;

B, described charging and discharging circuit by the capacitor group of forming by several capacitors C1, C2Cn, be connected high voltage control pipe TH1, TH2 between high pressure end line (1,2) and the capacitor group, be connected low voltage control pipe TL1, TL2TLn between low pressure end line (3) and the capacitor group, be connected separating tube TG1, the TG2TGn-1 between each electric capacity of capacitor group and be connected that connecting to neutral pipe TO1, the TO2TOn between each electric capacity and low pressure end line (4) forms in the capacitor group;

The control end of c, described high voltage control pipe TH1, TH2, low voltage control pipe TL1, TL2TLn, separating tube TG1, TG2TGn-1 and connecting to neutral pipe TO1, TO2TOn is accepted pulse control signal respectively, alternately change in conducting with under operating state with identical frequency, and, the conducting of described high voltage control pipe, separating tube and connecting to neutral pipe, low voltage control pipe and opposite by operating state.

2, DC converter according to claim 1, it is characterized in that, described charging and discharging circuit is made up of charging and discharging circuit I and charging and discharging circuit II, described charging and discharging circuit I has identical circuit structure with the charging and discharging circuit II, in loop I and loop II two parts circuit each corresponding switching tube at one time in conducting or the operating state of ending opposite, two loop I, II discharge and recharge with complementing one another in time.

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