CN201360226Y - Adjustable DC power supply with low voltage and high current - Google Patents

Abstract

The utility model discloses an adjustable DC power supply with low voltage and high current, comprising a transformer, and a voltage regulating circuit and a rectification circuit which are connected with the transformer. Voltage is regulated at a primary side, and current is rectified at a secondary side. The transformer adopts a double reversed star connection. The adjustable DC power supply with low voltage and high current has the advantages of high power factor, small harmonic wave, low heat consumption, simple structure and energy consumption saving, being applicable to be used as a heating power supply in single crystal furnaces and industries of electroplating, electrolysis, and the like.

Description

A kind of adjustable DC power supply of low-voltage and high-current

Technical field

The utility model relates to a kind of DC heating power supply, specifically a kind of low-voltage and high-current regulated power supply.

Background technology

At present, generally the adjustable DC heating power supply of the low-voltage and high-current of Shi Yonging mainly is made up of the rectification circuit of the transformer of Y/ Δ connection and regulating circuit thereof, band interphase reactor, is tens volts and goes up kiloamperes, in the Circuit Fault on Secondary Transformer pressure regulation.Such power supply is formed the loss that has transformer leakage reactance big, transformer influences the defective that civil power, harmonic wave are big, power factor is low.

The utility model content

The technical problems to be solved in the utility model provides a kind of adjustable DC power supply that the low-voltage and high-current of uncontrollable rectification is carried out in pressure regulation, secondary of carrying out on the former limit of transformer, have power factor height, energy-conservation characteristics, be applicable to that industries such as single crystal growing furnace, plating, electrolysis make heating power supply.

For solving the problems of the technologies described above, technical solution adopted in the utility model is:

A kind of adjustable DC power supply of low-voltage and high-current comprises transformer and the regulating circuit and the rectification circuit that link to each other with transformer, and the transformer regulating circuit is connected to the former limit of transformer.

As improvement of the present utility model, described regulating circuit is by control silicon wafer brake tube G ₁-G ₆Three branch roads that constitute are formed, and two silicon controlled crystal brake pipes of each route parallel connected in reverse phase constitute, and its each branch road is serially connected in respectively in the transformer input circuit.

As further improvement, described transformer adopting double reverse-stars type connection, its rectification circuit is connected to the output of transformer.

Rectification circuit is a three phase controlled rectifier circuit, forms the diode D of rectification circuit ₁-D ₆Be connected to the output of the every phase of transformer respectively.

The input of the former limit A of described transformer, B, C three-phase is serially connected with fuse FU respectively _A, FU _B, FU _C

Former edge joint alternating current when the utility model uses is connected to the secondary side of transformer two ends with load and gets final product.

Owing to adopted technique scheme, the utility model is compared with existing common low-voltage and high-current DC power supply, has following characteristics:

1. carry out pressure regulation on the former limit of transformer, under the identical situation of load, electric current is little, and transformer loss is little;

2. adopt the double reverse-stars type connection, the leakage reactance of transformer does not influence civil power, so harmonic wave is little, and the power factor height;

3. adopt the three-phase fully-controlled rectification, voltage waveform is continuous, and current waveform is continuous.

4. in phase (20ms) weekly, each thyristor ON time of average ON time of each diode and existing DC power supply is all 6.7ms, but current value of the present utility model is half as large, and thermal losses is little, helps heat radiation;

5. fuse installation site difference, heat waste are also different: according to Q=i ²Rt is because of the electric current of current ratio existing power supply of the present utility model is little a lot, so thermal losses is also little a lot.

To sum up, the utility model is compared with existing existing low-voltage and high-current DC power supply, and obtained technological progress is: the power factor height, harmonic wave is little, hear rate is little, has characteristics simple in structure, energy efficient, is applicable to that industries such as single crystal growing furnace, plating, electrolysis make heating power supply.

Following the utility model will be described in further details in conjunction with Figure of description and specific embodiment.

Description of drawings

Fig. 1 is the electrical schematic diagram of the utility model embodiment;

Fig. 2 is the voltage oscillogram of AC side in actual applications embodiment illustrated in fig. 1;

Fig. 3 is and the corresponding dc voltage oscillogram of Fig. 2;

Fig. 4 is a kind of electrical schematic diagram of existing common power.

Embodiment

The following example only is used to further specify the utility model, does not limit the utility model.

Embodiment (one)

A kind of adjustable DC power supply of low-voltage and high-current comprises transformer and regulating circuit thereof, rectification circuit as shown in Figure 1.Transformer adopting double reverse-stars type connection wherein, regulating circuit is located at the former avris of transformer.

Regulating circuit comprises by silicon controlled crystal brake pipe G ₁-G ₆Three branch roads forming are serially connected with respectively in the input and the circuit between winding of the former limit A of transformer, B, C three-phase.Wherein insert the route silicon controlled crystal brake pipe G in the A phase inlet wire side ₁, G ₄Reverse parallel connection is formed; Correspondingly, the route silicon controlled crystal brake pipe G in the access B phase inlet wire side ₂With G ₅Reverse parallel connection is formed; Insert the route silicon controlled crystal brake pipe G in the C phase circuit ₃With G ₆Reverse parallel connection is formed.The input of the former limit A of transformer, B, C three-phase is serially connected with fuse FU respectively _A, FU _B, FU _C

Transformer secondary winding U, V, W, U ', V ', W ' are connected with each other, and wherein winding U ', V ', W ' are opposite with the polarity of other winding U, V, W; Described rectification circuit is a six phase half wave rectifying circuit for the three-phase fully-controlled rectification, by diode D ₁-D ₆Form, wherein diode D ₁, D ₃, D ₅Positive level be connected in series with the lambda line side of winding U, V, W respectively, other three diode D ₂, D ₄, D ₆Positive level be connected in series with the outlet side of winding W ', U ', V ' respectively, access point be positioned at winding U, V, W, U ', V ' and W ' parallel with one another before.

As follows when present embodiment should be used as the single crystal growing furnace heating power supply with the actual effect of using conventional DC power supply shown in Figure 4:

1. energy-saving analysis

(1) the application apparatus thermal losses is analyzed

The same time, same place, rated power is all the two cover czochralski crystal growing furnaces of 60kw, produces 8 inches monocrystalline silicon of 45kg respectively, and input is provided by civil power three-phase alternating current 380V, and related data is as follows:

Above-mentioned test data is carried out in interchange A, B, C three-phase inlet wire side, in whole process, uses the actual electric power 57.7kw of equipment of conventional DC power supply; Use the equipment of DC power supply that present embodiment provides, actual electric power is 49.8kw, saves energy 180kwh, energy-conservation 12%.Every degree electricity can be saved 144 yuan according to 0.8 yuan of calculating.Every single crystal growing furnace can be saved electricity consumption 60,000 degree every year, adds up to 4.8 ten thousand yuan.

(2) power supply Thermal Efficiency Analysis

In the unit interval, the DC side power output differs 2.24kw, and this is that factor by single crystal growing furnace body of heater itself causes, as: thermal field effect, recirculated water cooling etc. can be ignored.

The three-phase fully-controlled rectification can be regarded as six phase half-wave rectifications.Suppose that the interchange of rectifying device surveys voltage waveform as shown in Figure 3, the no-load voltage ratio of supposing transformer simultaneously is 8: 1, and DC voltage effective value is:

$U_e=\sqrt{\frac{6}{2\mathrm{\π}}{\∫}_{\mathrm{\α}}^{\frac{\mathrm{\π}}{3}}{(\sqrt{2}*U_2*\sin \mathrm{\ωt})}^{2}d\left(\mathrm{\ωt}\right)}---\left(1\right)$

$=0.977*U_2*\sqrt{0.957-0.5*\sin 2\mathrm{\α}-\mathrm{\α}}$

α=13 ° that draw present embodiment by experimental data, Fig. 1 must have DC power supply α=8 ° by Fig. 4.Therefore as can be known: the present embodiment voltage waveform is continuous, and current waveform is continuous.

(3) diode, the loss analysis of thyristor and fuse

The volt-ampere characteristic of semiconductor diode, in conducting constantly, the electric current of the process of pipe is that the exponential form with the pipe pressure drop increases, and is calculated value so we get the maximum pressure drop of pipe in conduction period.

A. among Fig. 1, select diode, take all factors into consideration its parameter, only do reference, it is on-state average current 2000A, peak on state voltage 1.7V, and at any one time, consumed power is P=UI=1.7 * 1360=2312 (W);

The on-state average current of thyristor is 300A, peak on state voltage 2.3V, and at any one time, consumed power is P=UI=2.3 * 300 * 2=1380 (W);

Fuse is selected rated current＜160A, and by the molten data that provide in west, loss＜12W gets maximum 12W.

The DC power supply that embodiment provided, its total thermal losses are P=2312+1308+12 * 3=3656 (W).

B. in Fig. 4, select thyristor, its on-state average current is 2000A, and peak on state voltage is 2.6V, and at any one time, consumed power is P=UI=2.6 * 2000 * 2=10400 (W);

Fuse is selected rated current 2000A, and loss＜110W gets maximum 110W.

The total losses of existing product shown in Figure 4 are p=10400+110 * 2=10620 (W).

C. as can be seen, the loss of existing conventional DC power supply is about 3 times of loss of the utility model embodiment from above derivation.

(4) loss analysis of transformer

The loss of transformer and the ferromagnetic material of selection, manufacturing process are relevant, and also relevant with size, load size, the frequency size of primary side input voltage, it is a lot of to relate to factor, and we only do to analyze qualitatively now.Suppose that except transformer other condition is ideal conditions, the electric power components and parts do not have loss, α=30 °, and γ=0, current/voltage is stable, and the D.C. resistance of Transformer Winding is also identical.So, the loss of transformer comprises copper loss and iron loss two parts.

A. copper loss comprises basic copper loss and additional copper loss, and the D.C. resistance that basic copper loss is a winding causes that it equals the product of the quadratic sum D.C. resistance of electric current; Additional copper loss comprise the kelvin effect that causes by stray field make the lead effective resistance become big and the copper loss that increases, multiple conducting wires and around the time inner circulation loss etc.Additional copper loss and copper loss is the same substantially is with square being directly proportional of load current.Additional copper loss is difficult to accurate calculating, so, can think that they are approximately 0.5～5% of basic copper loss.

With reference to figure 1, the u phase voltage u ' phase voltage of the secondary winding of transformer in the present embodiment, v and v ', w and w ' all differ 180 °, so electric current also differs 180 °, their amplitude equates.Any one being example mutually, though that phase current iu and iu ' go out now is different, its mean value all is i/6, and average current equates and winding polarity is opposite, so the direct current ampere-turn of having cancelled each other has been eliminated the direct current flux gesture.At any one time, two diode current flows are arranged, the average current by each diode is i/2, so at any one time, basic copper loss is Pcu=(i/2) ²* R * 2=(i ²R)/2=(1360 ²* R) ÷ 2=924800R (W).

Among Fig. 1, common cathode group positive half period conduction, the transformer of flowing through is a forward current, and the anode negative half-cycle conducts electricity altogether, and the transformer of flowing through is a negative current, does not also have the direct current flux gesture in the transformer winding.At any one time, two thyristor conductings are arranged, the average current by each thyristor is i, so at any one time, basic copper loss is Pcu=i ²R * 2=1240 ²* R * 2=3075200R (W).

As seen, the basic copper loss of existing conventional DC power supply is 3.29 times of the utility model embodiment.

B. iron loss comprises basic iron loss and additional iron loss, transformer fe magnetic hysteresis loss and eddy current loss in the heart during basic iron loss, square being directly proportional of approximate and primary side input voltage; Additional iron loss is mainly caused by manufacturing process, also is directly proportional with input voltage approx, and additional iron loss is difficult to accurate calculating, is generally 15～20% of basic iron loss.

The basic iron loss of the utility model embodiment is Pfe=U ²/ R=47.5 ²/ R=2256.25/R (W)

The basic iron loss of existing conventional DC power supply is Pfe=U ²/ R=380 ²/ R=144400/R (W)

As seen, the basic iron loss of existing conventional DC power supply approximately is 64 times of the utility model embodiment.

When calculating certain a part of loss, we think that other conditions all are desirable.Slave unit actual motion record data also prove: above-mentioned inference is correct.

2. the influence of harmonic wave and power factor analysis, leakage reactance

In above inference, all ignored the leakage inductance of transformer, but in fact always had leakage inductance on the winding of transformer.So electric current drops to 0 suddenly from I, perhaps electric current rises to I from 0, and the electric current commutation will can not be finished through after a while moment.Therefore, pairing we represent with γ with the commutation overlap angle commutation process during this period of time.Suppose that two kinds of every leakage reactance Xb that convert secondary side mutually of transformer equate, by the formula of three-phase bridge fully controlled rectifier

$\cos \mathrm{\α}-\cos (\mathrm{\α}+{\mathrm{\γ}}_2)=2*I_d{X}_B/\sqrt{6}{U}_2---\left(2\right)$

The uncontrollable rectification formula of six phase half-waves

$\cos \mathrm{\α}-\cos (\mathrm{\α}+{\mathrm{\γ}}_1)=\sqrt{2}*I_d{X}_B/U_2---\left(3\right)$

α=0 substitution,

$\frac{1-\cos {\mathrm{\γ}}_2}{1-{\cos \mathrm{\γ}}_1}=2/\sqrt{3}---\left(4\right)$

Calculate and draw γ 2＞γ 1, promptly the overlap angle of the promptly existing conventional DC power supply of Fig. 1 is the overlap angle of the utility model embodiment greater than Fig. 2.Overlap angle is big more, and it is dark more to cause phase voltage waveform breach to occur, causes waveform distortion of the power supply network serious more, and the power factor of rectifying device is descended, and the mains ripple coefficient increases.

Comprehensive above-mentioned theory and actual data analysis be as can be known: carry out pressure regulation, secondary on the former limit of transformer and carry out the DC power supply of full-controlled rectifier and compare with conventional power source, have the power factor height, energy-saving advantages.

Claims (5)

1, a kind of adjustable DC power supply of low-voltage and high-current comprises transformer and the regulating circuit and the rectification circuit that link to each other with transformer, and it is characterized in that: the transformer regulating circuit is connected to the former limit of transformer.

2, the adjustable DC power supply of a kind of low-voltage and high-current as claimed in claim 1 is characterized in that: described regulating circuit is served as reasons and is controlled silicon wafer brake tube (G ₁-G ₆) three branch roads constituting form, two silicon controlled crystal brake pipes of each route parallel connected in reverse phase constitute, and its each branch road is serially connected in respectively in the transformer input circuit.

3, the adjustable DC power supply of low-voltage and high-current as claimed in claim 1 or 2 is characterized in that: described transformer adopting double reverse-stars type connection, its rectification circuit is connected to the output of transformer.

4, the adjustable DC power supply of low-voltage and high-current as claimed in claim 3 is characterized in that: rectification circuit is a three phase controlled rectifier circuit, forms the diode (D of rectification circuit ₁-D ₆) be connected to the output of the every phase of transformer respectively.

5, the adjustable DC power supply of a kind of low-voltage and high-current as claimed in claim 1 is characterized in that: the input of the former limit A of described transformer, B, C three-phase is serially connected with fuse (FU respectively _A, FU _B, FU _C).

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