DE1488540B2 - ELECTRONIC DEVICE FOR CLEANING DC POWER SUPPLIES FROM UNWANTED EXTERNAL VOLTAGES - Google Patents

Description

filter for smoothing, the part of which to the right of the dashed vertical line through the equivalent circuit diagram F i g. 2 can be represented.

For the sake of simplicity, it should be assumed that, for. B. the superimposed alternating voltage still present at Cl consists of a sinusoidal voltage with a frequency of 30 Hz and an effective value of 1 volt. The inductance of the choke coil L 2 is (practical example for a rectifier with 30 A output direct current at 220 V) 50 mHy.

It is readily understood that if it succeeds, an alternating current with the Q through the cross member

Amplitude / = - to be driven with the correct phase-

position, the entire AC voltage drops at LI and no longer appears at the DC output. In practice, these conditions are achieved in that the cross member Q consists of a controllable element T with a small time constant (e.g. electron tube or transistor), which is controlled by an amplifier without phase rotation (e.g. direct current differential amplifier), the input of which is via a direct current block Cl at the output of the filter (Fig. 3). The quiescent current of the cross member is chosen so that it matches the amplitude

ίο equal to the required compensation alternating current and when the compensation alternating current flows, it goes back to zero when the peak value is negative, with a positive peak value to double the quiescent current.

From the example chosen it can be seen that the quiescent current through the cross member only

J _Q = _L_ = = - = 0.106A (ω = 2π /)

ω L 2π x 30 x 0.05 9.4

must be, compared to a rated current of 30 A, which is a deterioration in efficiency by the Cleaning device by 0.3%. The power of the cross member must be 220 · 0.106 = 23.3 W. compared to 6600 W useful power. From the example chosen it can also be seen that the device not only to eliminate external voltages caused by transient processes can serve, but with appropriate dimensioning also to screen out the superimposed AC components resulting from rectification.

This results in a considerable reduction in the expenditure on filter elements to be used.

If the voltage at Cl (Fig. 1) is not sinusoidal, but of some kind, as it is caused by mains pulses at the rectifier input, its drop at L 2 can be forced by changing the current in the cross member at any point in time according to the law

Tr ro
Ua = L2

German
follows, which is automatically the case when the cross member, as mentioned in the simplified example, is controlled.
Like F i g. 4 shows, in the device described, the smoothing takes place by "tearing down" the wave crests to the level of the wave troughs.

A variant of the device chooses the opposite path and smooths by filling in the wave troughs. An additional power source (FIG. 5) is required for this. This application is particularly appropriate if the output DC voltage is high, a transistor should be used as the feed element and In any case, there is an emergency power battery that is buffered to a higher voltage than the DC output voltage that can be used as an auxiliary power source (Figs. 6 and 7).

Reference symbols used:

Cl filter capacitor,

C2 DC block,

Ll choke coil,

L2 choke coil,

Q cross member,

T taxable body with
small time constant.

40

1 sheet of drawings

Claims (2)

1 2. reduce this small value. Not so easy Patent claims:: is the elimination of the interference voltage that results from transient processes. 1. Electronic device for cleaning up by switching operations in the local alternating current network DC power supply systems of undesirable 5 are impulses with steep fronts through the dense External voltages, consisting of a line rectifier, transferred to the filter input; this impedance, The low-pass filters collide with a cross member and an electronic pulse in their natural resonance Amplifier, thereby marked frequency and appear as dampened Schwinn e t that the cross member and the electronic conditions in the DC output voltage. In the indu amplifier a very small control time constant io strie or the city networks have such impulses more And the corn flowing through the cross member per second with very different amplitudes Current through the amplifier, which has an on and transmitted as disruptive external voltages DC block to the DC output to the DC output. is coupled, is controlled in such a way that the For small feed currents are already used to eliminate Interference component predominantly as alternating voltage of such external voltages transistors or voltage drop occurs at the series impedance. Electron tubes as series regulators with a short time 2. Device according to claim 1, characterized ge constant used, which at the same time also characterizes the stability, that the cross member serve from a Strom- sization of the DC voltage. With a large source with higher voltage than the desired strength offices with central power supply and DC voltage An additional current in the 20 several thousand amplifiers can be provided by the supply current direct current output feeds in in such a way that the disturbance requirement is up to several hundred amperes, voltage again predominantly as alternating It is the series regulator economically no longer voltage drop occurs at the series impedance. reversible because of its poor efficiency, 3. Device according to claim 1, characterized in that there are no corresponding series regulating elements indicates that the cross member consists of a Tran- 25 for high currents with a small time constant and the sistor exists. disproportionately large space requirements. 4. Device according to one of claims 1 to 3, also the permissible tolerance of the same span is thereby characterized in that the DC voltage fluctuations by 2 to 3 orders of magnitude lock consists of a capacitor. higher than the permissible external voltage. So it is 5. Device according to one of claims 2 to 4, 39 nonsensical, the output DC voltage within so characterized in that stabilize as additional current narrow limits, which is the case with the series source the emergency battery of the power supply regulator with simultaneous stabilization of the equation system is used. . . ... voltage inevitably results, apart from the Stability difficulties that arise with such high 35 Strengthening of the series regulator control amplifier as well are not easy to deal with. The invention is based on the object also The present invention relates to an electronic device suitable for large utility systems Device for cleaning up direct current voltage to eliminate interference voltages with improved supply systems of undesired external voltage 40 system efficiency and reduced effort nings. create. (The international exchange of broadcast and This task is thereby achieved according to the invention TV programs mean that a high resolution, that the cross link and the electronic A very small control time conimmer, qualitative music transmission via NF-cable on stronger of the facility greater distances are needed, with up to. 10 45 constant and the one flowing through the cross member or 20 inter-repeater stations switched on current through the repeater, which via an equalizer have to. Current lock coupled to the DC output The quality of such transmissions is very important, it is controlled in such a way that the interference component makes high demands. . The recommendations, mainly as an alternating voltage drop at the CCITT, apply as an international standard. This 5 ° series impedance of the device occurs
write in addition to the frequency response and the highest permissible noise voltage for such over- The device proposed according to the invention deliberately dispenses with a stabilization of the discharges likewise a maximum permissible external voltage DC voltage and limits it to the voltage on the line (max. 62 mV on a superimposed external voltage from the output equal 2500 km long line, 30 to 20,000 Hz). '55 to filter out voltage. The stabilization of the The fulfillment of these regulations sets very high direct voltage to the required value, so requirements can be placed on the direct current supply sources by other lossless methods with amplifiers in the intermediate stations. This feed a significantly better efficiency (current sources consist almost exclusively of equal savings, a reduction in the loss funnels to be discharged, which are fed from the local alternating current network). As a result, the power that is supplied by the rectified alternating current device is reduced by one or two through downstream low-pass filters to the required order of magnitude, so the space requirement is therefore very small residual ripple is smoothed (e.g. also roughly proportionally smaller,
a few millivolts at DC voltage, which can be up to a few below the invention with reference to 100 volts). 65 explained in more detail on the drawings. Due to the corresponding filter effort, it is definitely The principle mode of operation of the device possible, the amplitude of the superimposed alternation is shown in FIG. 2. The FIG. 1 shows a classic voltage resulting from the rectification to the rectifier circuit with subsequent low-pass