WO1989010024A1

WO1989010024A1 - Arrangement for controlled energy transfer for electrical supply, especially for reducing switching transients

Info

Publication number: WO1989010024A1
Application number: PCT/HU1989/000013
Authority: WO
Inventors: István HUISZ; Nándor BITTERMANN; István FÖLDESI; Imre Blaumann; Ferenc Kopornoky; Zoltán VARANNAI
Original assignee: Hiradástechnika Szövetkezet
Priority date: 1988-04-08
Filing date: 1989-04-07
Publication date: 1989-10-19
Also published as: FI895872A0; EP0396631A1; HUT49759A; KR900701080A; HU201629B; JPH03500600A; DD283879A5

Abstract

The invention relates to an arrangement for controlled energy transfer for electrical supply, first of all for reducing switching transients, where alternating voltage source (Uo) is connected to consumer(s) (Sa). The essence of the invention lies in that between alternating voltage source (Uo) and consumer (Sa) there is a switching circuit (VK) connected through watching circuit (F1) and through control circuit (V); the other input of said switching circuit (VK) is connected to a further output of watching circuit (F1).

Description

ARRANGEMENT FOR CONTROLLED ENERGY TRANSFER FOR ELECTRICAL SUPPLY, ESPECIALLY FOR REDUCING SWITCHING TRANSIENTS

The invention relates to an arrangement for controlled energy transfer for electrical supply, especially for reducing switching transients.

One of the most important parts of electrical devices operated from mains is the supply unit. Its task is multiple, shock-proof arrangement (galvanic disconnection from mains), production of different supply voltages required by the circuits, and equalizing and stabilizing the changes of mains voltage, protection of circuits, etc.

The fulfillment of stabilizing function even by devices of 50-200 W power input causes a big problem. The changes of the mains voltage may exceed +/- 10 percent or in special cases even -15, +10 percent can be required. In our supply units of traditional structure (transformer of mains - rectifier - filter condensator - stabilization circuit ) even at the minimum of mains voltage a higher voltage than the output voltage must be ensured on the filter condensator. By nominal mains voltage, and especially by the maximal mains voltage this causes unbearable dissipation on the bypass unit of the stablizer. The situation is getting worse by the fact that in the greater part of the devices the consumption is limited to low supply voltage circuits (5V digital circuits). As mass result a derived efficiency grade of 30-40 percent can be estimated as good. The devices are of big dimensions, are heavy and too hot. With the spreading of the computers, switching power supply units have cone to the front. These units after the rectifiing of the mains voltage produce the energy transfer and the voltage transformation by switching the main voltage with the medium frequency. These supply units are of small dimensions, have little weigh and have good efficiency.

Their big problem is that the important radiating disturbance caused by them is hardly decreasable, and they need high quality modern circuits, which are more expensive further the number of the electronic elements used is very high and the faults of these decrease reliability.

Several trials have been made for the improvement of efficiency of analogue supply units with the use of precontrol. Because of the relatively high current intensity thyristors can be used as switching elements - these however in case of direct current can only be switched in electrically and not switched out. Thus control is only possible in the return interval of mains voltage. This requires a so-called preregulation control circuit - that has complicated and uncertain operation. Further problem is the choosing of the filter condensators. In the filter circuits ensuring good filter characteristic the required high capacity condensator. connected to the mains, produces in energy-free state a high current impulse, that can damage the rectifiers, or blow the fuses; the maximum voltage is too high for the filter condensator.

Such switches are also used that do not let the mains voltage changes fully to the consumer and the device uses prestabilizer. The essence of prestabilization is that it is using controlled rectifiers between the transformer and the input of the stabilizer so as to limit to the needed minimum the voltage difference between the input and the output of the stabilizer during the alteration of voltage of the charge and the mains voltage. This way dissipation of the stabilizer can be limited to the minimum.

Reference can be found in special literature to regulation on primary side, though these do not possess the advantages of our invention. USP 4 524 413 uses a controlled switch that is solely of secondary side structure and does not possess the advantages of the invention either.

In experimental realizations that are the closest to the solution according to our invention, we meet such connection that interferes for the solution of the problem directly through the terminals of the mains. In this solution experiments are made with the traditional switching elements (thyristor, triac), with these the regulation cannot be realized due to the known problem. Hence, the invention is an arrangement for controlled energy transfer for electrical supply, first of all for reducing switching transients where alternating voltage source is connected to consumer(s) and is realized according to the invention so that between alternating voltage source and consumer there is the first input of switching circuit connected through watching circuit and the other input of said switching circuit through control circuit connected to a further output of watching circuit. A preferred embodiment of the invention is where between switching circuit and consumer there is a further transducer installed.

That preferred embodiment of the arrangement according to the invention where supply voltage source connected to consumer switches off the supply if the voltage rises above a given value, is realized so that control circuit has a further input and said input is connected through a further watching circuit to consumer.

Another preferred embodiment of the invention is where the transducer is a transformer and the primary winding of said transformer is connected in series with switching circuit or the primary winding of said transformer consists of two parts between said parts switching circuit is installed in series or switching circuit is formed by controlled semiconductor switch and the gate of which is connected to output of control circuit.

So as the supply energy measuring on the consumer could be reliable, it is advisable that secondary watching circuit is arranged for measuring one parameter of the consumer and said watching circuit consists of error signal generator and a coupling element without moving contacts optocoupler connected to the output of said error signal generator, the output of the coupling element forms the output of watching circuit; further transducer is a transformer, on the secondary winding of said transformer a rectifier is connected, to the output of said rectifier a further stabilizer is also connected and watching circuit is shaped for measuring the voltage between the input and the output of the stabilizer. The invention is based on the recognition that if we make from the consumer a consumer having controlled disconnection than in given circuit the flow of energy can be kept within given limits, which is a big advantage especially in case of high power consumers by the dimensioning of mains, thinking of the cross-section, overheating, etc. of the cables.

The basic idea of the invention is that we watch in the line of energy transfer one of the parameters, eg. current or voltage and if the parameter exceeds a predefined value, the circuit is disconnected, eg. the consumer is switched off.

Certainly simultaneously several parameters can be watched and control can be made based on them. Such eg. in case of supply unit the flow of energy on the output power transistor or the voltage on it or eg. the output short circuit.

The invention will be described in preferred embodiments by means of figures enclosed.

Figures 1-4 show the block diagrams of preferred embodiments of the arrangement according to the invention; Figures 5-7 represent embodiments of the transducer; Figure 8 illustrates an arrangement according to the invention.

Figures 1-4 show the block diagrams of preferred embodiments of the arrangement according to the invention where voltage source Uo is the alternating voltage connected to consumer Sa and where consumer Sa is connected to voltage source Uo through watching circuit Fl and switching circuit VK so that watching circuit Fl is equiped also with a further output that is connected through control circuit V to the other input of switching circuit VK.

On the embodiment of Figure 2 there is connected switching circuit VK and consumer Sa a transducer A, suitably a transformer, while on the embodiment of Figure 3 there is a further watching circuit F2 the input of which is connected to consumer Sa and the output of said watching circuit F2 is connected to a further input of the control circuit V.

On the embodiment of Figure 4 we can find all the already mentioned units, ie. both watching circuits F1 and F2, transducer A and control circuit V and switching circuit VK.

Figures 5-7 show an example of embodiment of transducer A and switching circuit VK respectively, where transducer A is a transformer, with the primary winding of said transformer is connected in series switching circuit VK eg. a controlled semiconductor switch. On the embodiment of Figure 5, primary winding of transformer Tr is divided into two parts and switching circuit VK is arranged inbetween.

Figure 8 shows an embodiment of the arrangement according to the invention in detail, where voltage source Uo is an alternating voltage generator, to the output of which are connected three series circuit consisting of two diodes D1, D2; D3, D4; D5,D6 each. To voltage source Uo there are connected two resistors RA and R3 in series. The resistors RA and RB and the diodes D1, D2; D3, D4 and D5, Do form the watching circuit F1. Control circuit V that is on one side connected to watching circuit Fl on the other side to switching circuit VK is consisting of two comparators K1 and K2. Output of comparator K2 is connected to the reference input of comparator K1, while to the other measuring input of this same comparator K1 is connected the common point of the diodes D5, D6 through voltage divider consisting of two resistors R1 and R2. To the reference input of comparator Kl is also connected the ouput of the second watching circuit F2 that can in given case modify the interference, so that the two signs are practically superponing, the output of comparator K1 is connected to switching circuit Vk eg. the control input of the controlled semiconductor switch, which is installed in series between the two parts of the primary winding of the transformer TR. By the example embodiment transducer A also contains a rectifier G, more exactly by this embodiment consumer Sa is supplied with direct currect and rectifier G is connected to consumer Sa through stabilizer St. Thus in this case watching circuit F2 watches the voltage on stabilizer St but the temperature or current of the power transistor of the stabilizer St could be measured too.

Input and output of stabilizer St is connected to optocoupling through error signal generator HK, the output of said optocoupling is than connected to the refernce input of comparator K1.

In the case of arrangement shown on the Figure we can see that comparator K1 compares the value of the mains voltage corrected with the error signal with the predefined value given on resistance R1 and R2 and if the registered sign difference exceeds a predefined limit value, it switches off the series connection between the primary winding parts of the mains transformer TR.

Comparator K2 compares the energy flowing through the primary winding of transformer Tr with a predefined value and if the measured value exceeds the predefined value it switches off the switching circuit VK.

The watching of the energy is made by resistors RA and RB and the polarity of voltage to be measured is choosen with the help of the diodes D1, D2.

Claims

C L A I M S

1. Arrangement for controlled energy transfer for electrical supply, first of all for reducing switching transients, where alternating voltage source (Uo) is connected to consumer(S) (Sa) characterized in that between alternating voltage source (Uo) and consumer (Sa) there is a switching circuit (VK) connected through watching circuit (Fl and through control circuit (V) the other input of said switching circuit (VK) is connected to a further output of watching circuit (F1).

2. Arrangement according to claim 1 characterized in that between switching circuit (VK) and consumer (Sa) there is further transducer (A) installed.

3. Arrangement according to claim 1 or 2, charac terized in that control circuit (V) is equiped with a further input and said input is connected through a further watching circuit (F2) to consumer (Sa).

4. Arrangement according to any of claims 1-3, characterized in that the transducer is a transformer (Tr) and the primary winding of said transformer (Tr) is connected in series switching circuit (VK).

5. Arrangement according to any of claims 1-3, characterized in that transducer is a transformer (Tr), the primary winding of said transformer (Tr) consists of two parts, between said parts switching circuit (VK) is installed in series.

6. Arrangement according to to claim 4 or 5, characterized in that switching circuit (VK) is formed by controlled semiconductor switch and the control electrode of said switch is connected to output of control circuit (V).

7. Arrangement according to any of claims 1-6, characterized in that secondary watching circuit (F2) is for measuring one parameter of consumer (Sa), and said watching circuit (F2) consists of error signal generator (HK) and of coupling element without moving contacts eg. optocoupler connected to the output of said error signal generator (HK) the output of the coupling element forms the output of watching circuit (F2).

8. Arrangement according to any of claims 1-7, characterized in that transducer (A) is a transformer, on the secondary winding of said transformer a rectifier (G) is connected, to the output of said rectifier (G) a further stabilizer (St) is also connected and watching circuit (F2) is for measuring the voltage between the input and the output of the stabilizer (St).