DE3403895A1 - Circuit arrangement for voltage control and voltage conversion, particularly of a solar generator - Google Patents

Abstract

The invention relates to a circuit arrangement for controlling the voltage of a generator having an at least partially current-impressing characteristic, particularly a solar generator (1) for outputting a voltage, transformed up to a desired level, to a load (8) with low source resistance or low source impedance. For controlling the voltage, a series two-step controller (2, 3, 7) with capacitive storage (3) is provided, the switch (2) of the two-step controller and the generator (7) being decoupled via a transformer (5) from the capacitive storage (3) and the load (8) which is connected in parallel therewith. The transformation ratio of the transformer (5) is selected in such a manner that a voltage having the desired high level is obtained at the output of the circuit arrangement. In addition, the switching frequency of the switch (2) and the capacitance (C) of the capacitive storage (3) are selected to be high enough for a low source resistance or a low source impedance to be present at the output of the circuit arrangement. <IMAGE>

Description

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Circuit arrangement for voltage regulation and voltage conversion, in particular of a solar generator

The invention relates to a circuit arrangement for voltage regulation of a generator with at least partially current-shaping characteristic, in particular one Solargeneratorε, according to the preamble of the claim 1.

A solar generator or a generator with a similar characteristic, e.g. B. a solar generator simulator is one Source of electrical power, which is characterized by a characteristic current / voltage characteristic.

The characteristic curve here has a characteristic curve part with current imprinting and a characteristic line part with voltage imprinting, which one into the other in a relatively short range skip over, in which the point of maximum performance lies. The source resistance is based on the open circuit voltage or the source impedance initially desirably low; it increases in relative terms with increasing exposure strongly stress-forming part of the characteristic curve, what happens when connecting is often not desired by loads, achieved in the point of maximum power output according to the The slope of the tangent to the characteristic curve has the value -U / I and then increases in the current-shaping part of the characteristic curve in the direction of the short-circuit point to very high values.

When using such solar generators in space travel, z. B. in a television broadcast satellite, must provide high DC voltages with low source resistance with such solar generators be, so z. B. to supply a traveling wave tube amplifier for direct television via communications satellites. The tensions are in the range of a few kilo-

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volt, ζ. B. 8 KV. Since individual solar cells have operating voltages of around 1/2 V with a current of around 1/4 A can deliver such high voltages with the required Services from a solar generator cannot be delivered directly because such a solar generator is so large would be that he would not economically go into space with today's means, e.g. B. in a stationary orbit the earth could be transported. It is therefore necessary to adjust the output voltage of the solar generator to the to step up the required high voltage. The usual route taken with today's television satellites is to first get a better source from the solar generator via so-called shunt regulators Make voltage constancy with low source resistance. Then the output DC power converted into alternating current power and transformed to the desired voltage level. Because the voltage regulator and the converter or transformer have some spatial distance from one another, is a costly one and complex readjustments are unavoidable. In addition, this separation of controller and converter the weight of the entire circuit arrangement is quite high.

The invention is based on the object of a circuit arrangement of the type in question, with which a simple voltage regulation and transformation on high voltages with low weight is possible.

This object is according to the invention by the characterizing Part of claim 1 specified features solved.

According to these features, voltage regulation and voltage step-up become one complex Circuit arrangement combined. As a voltage regulator

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becomes a known two-position controller with capacitive Memory selected. .

With two-point control of the solar generator voltage the source resistance of the solar generator is used as an ohmic series element of the series two-position controller.

In the case of solar generators, such a two-point control, which is simple in principle, is not used because the changing source resistance is viewed as a disadvantage, which is included in the regulated output voltage and there would have to be eliminated at great expense.

For stepping up the output voltage is But precisely such a two-point control is advantageous, since the two-point control alternates processes, i. H. triggers switching between a minimum voltage threshold and a maximum voltage source. Through this there is the possibility of using the solar generator with the Switch of the series two-position controller on the one hand and the capacitive storage device with the load connected in parallel on the other hand, to be decoupled in a transformer. The transmission ratio of the transformer is chosen so that that the desired high output voltage is achieved. The capacitance on the secondary side of the transformer transforms itself with the transfer ratio to the primary side and interacts with there the solar generator.

As such, such a circuit arrangement does not yet produce the desired low source resistance. Of the dynamic internal resistance Rj_ of the entire arrangement given by the differential of current and voltage

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dU / dl, whereby the phases are neglected here. Since the charge supplied in the switching cycle must be the same as the charge discharged, the internal resistance R ^ can be approximated by the ratio of the discharge time £ t to the capacitance C / ie .RjS & t / C by choosing a shorter discharge time, ie by choosing a high switching frequency of the series -Two-point controller, and a sufficiently large capacitance value of the capacitive storage, the internal resistance of the arrangement, and thus the source resistance of the power source made available can be made small.

The transformer for stepping up the voltage is preferably designed as a push-pull converter. Output side the capacitance connected in parallel via a rectifier circuit, ζ. B. a four-way diode circuit connected.

In a circuit arrangement according to the invention, the voltage regulation and the step-up transformation is the Voltage quasi, lossless and the regulation takes place in the current-shaping area of the characteristic curves. Used by the solar generator If an excess performance is offered over the required performance, this excess performance remains as a mismatch loss in the solar generator. Through the Ohmic (capacitive nature of the transformation or implementation the voltage, the controlled system has optimal dynamics and no commutation problems. Through the Combination of regulation, implementation and solar generator. Can change the dimensions and weight of the overall circuit arrangement compared to conventional devices, can be reduced by about half. By taking in of the generator in the control / conversion principle, this circuit arrangement is only at one voltage source with corresponding characteristics

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operable.

The invention is based on two exemplary embodiments
the drawing explained in more detail. In the drawing show:

Pig. 1 a characteristic diagram for current and voltage
a solar cell of a solar generator;

Fig. 2 schematically shows a circuit diagram for a

Circuit arrangement for voltage regulation of a
Solar generator with voltage transformation
according to the invention in a first embodiment;

3 shows a second exemplary embodiment for a circuit arrangement according to the invention.

In Fig. 1 is a family of twelve characteristic curves
Q) to (J5) of a solar cell of a solar generator are shown. The current E is plotted in amperes on the ordinate, and the voltage ü in volts is plotted on the abscissa. That
The overall characteristic field of the solar generator corresponds to the characteristic field shown with higher current and voltage values. Based on the short-circuit voltage
at zero volts the characteristic curve is current,
Then slowly bends over, with the point of maximum power marked with a cross in this transition area, and then runs in the direction of the open-circuit voltage with, however, not as strong
Voltage imprint.

In Fig. 2, 1 is shown schematically a solar generator, which consists of a plurality of interconnected Consists of single cells. To regulate the voltage of the

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Solar generator 1 according to the above characteristic output DC voltage is a series two-point controller with capacitive storage is used. Only a switch 2 and a capacitor are of the series two-position controller 3 shown as capacitive storage. The solar generator 1 with the switch 2 in the longitudinal path is through a primary winding 4 of a transformer 5 completed «The secondary winding 6 is parallel to the capacitor 3; A diode 7 is connected between the secondary winding and the capacitor. In parallel with the capacitor 3 is a load 8, z. B. a traveling wave tube amplifier in a television broadcasting circuit of a communications satellite. This traveling wave tube amplifier comes with a high constant DC voltage of z. B. 8 KV operated with appropriate power.

In this circuit arrangement are solar generator and Switch on the one hand and capacitive storage and load on the other hand decoupled by the transformer. That Transmission ratio of the transformer 5 and the design of the solar generator 1 are matched so that the two-point control results in a nominal voltage of 0.4 V of a single cell according to FIG. The solar generator power is made available in accordance with the power Pq according to FIG. From Fig. 1 is It can be seen that the solar generator has this nominal power Pq available in the characteristic curve states (5) to ([2) can put.

Switch 2 of the series two-position controller is closed or opened when the voltage drops to a minimum value or reaches a maximum value. This switching range is indicated in Fig. 1 with a double arrow Δϋ. The switching range Δϋ is small

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chosen so that a high switching frequency of the series two-position controller results. The capacitance C of the capacitor 3 is chosen to be sufficiently large so that the dynamic Internal resistance of the specified circuit arrangement, i.e. the total source resistance of the regulated DC voltage source is made small.

The function of the series two-position controller from switch 2 with appropriate control and capacitor 3 is known and therefore does not need to be described in more detail here.

It is essential that the transformer 5 for stepping up or converting the voltage in the series two-point controller is integrated.

3 shows a further exemplary embodiment of a circuit arrangement for regulating the voltage of a solar generator and for stepping up the output DC voltage. For the same or the same Acting elements have the same reference numerals as in Fig. 1, but with a dash (') is added.

The end connections of a solar generator 1 'are connected, on the one hand, via a switch 2y , to one end connection of a primary winding 4' of a transformer 5 'and, on the other hand, to a central tap of the primary winding 4'. In parallel with the switch 2-, ι a switch 221 is provided which is connected to the other end connection of the primary winding 4 '. The end connections of the secondary winding 6 ¹ are connected to opposite connection points of a four-way diode circuit 7 ¹ ; the other two opposite points of this four-way rectifier circuit 7 'are labeled as capacitive

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Memory serving capacitor 3 'connected. Parallel the load 8 'is in turn connected to the capacitor.

The two switches 2-j ι and 221 and the capacitor form the two-position controller, which is similar to the first embodiment, but with voltage doubling is working.

The transmission ratio is also in this circuit arrangement of the transformer 5 'and the design of the solar generator T' matched so that the vertical straight line shown in FIG. 1 corresponds to the voltage regulation at 0.4 V single cell voltage. The switching range for the voltage is again chosen so narrow that a high switching frequency results. Together if the capacitance of the capacitor 3 'is selected to be sufficiently large, a lower one results in turn Source resistance or a low source impedance of the voltage source made available in this way for the load 8 '.

The solar generator is in a state corresponding to the characteristic curve (jp of the single cell of Fig. 1, the point is the NominalIeistung P _Q directly on this characteristic. On capacitor 3 ¹ then provides a symmetrical square wave current directly adjoining rectangles a. Because high capacity C of the capacitor are the flanks steep, the square tops are hardly chamfered. located at the solar generator 1 ¹ in a state in accordance with the characteristics (o) to ^ 2), and therefore provides a surplus power, the current pulse width is modulated. The excess power remains as a mismatch loss in the solar generator.

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Claims (4)

Circuit arrangement for voltage regulation and voltage conversion, in particular of a solar generator 5 Claims Circuit arrangement for voltage regulation of a generator with at least partially current-shaping characteristic, in particular a solar generator, for outputting a voltage that has been stepped up to a desired level to a load with a low source resistance or low source impedance, characterized in that the circuit arrangement includes a series two-point regulator (2 , 3, 7) with a switch (2) in the longitudinal path and a capacitive memory (3) in the transverse path between generator (1) and load (2), the operating point (P ₀ ) of which is in the current-dominant area of the generator gate characteristic (φ to ^)) is selected that the generator (1) with the switch (2) of the two-position controller on the one hand and the capacitive memory (3) of the two-position controller on the other hand, are decoupled via a transformer (5), which adjusts the voltage of the generator to the desired level Level transformed, and that the capacity (C) of the capacitive memory (3) and the switching frequency of the Two-point regulator are chosen so high that the desired low source resistance results. 2. Circuit arrangement according to claim 1, characterized in that the transformer (5 ¹ ) and series two-point ^{regulator (2 1} , 3 ¹ , 7 ¹ ) are designed as push-pull voltage regulator / converter, in which the connections of the generator (1 ¹ ) via a switch (2 ^ _t ) with one end connection of the primary winding (4 ¹ ) and with MBB 25th Patent department 34038 9459 a center connection of the primary winding (4 ¹ ) of the transformer (5 ¹ ) are connected and in which a second switch {22 ■) ^ ^es two-point controller is connected in parallel to the first switch (2 ..,) and with the second end connection of the primary winding ( 4 ¹ ) of the transformer (5 ¹ ) is connected. 3. Circuit arrangement according to Claim 1 or 2, characterized in that ^{a rectifier circuit is provided between the secondary winding (6, 6 1} ) and the capacitive memory (3, 3 '). 4. Circuit arrangement according to claim 2, characterized in that the end connections of the secondary winding (6 ') of the transformer (5') are connected to two opposite circuit points of a four-way rectifier circuit (7 '), and that the capacitive memory (3 ¹ ) with is connected to the other two opposite circuit points of the four-way rectifier circuit. 35