DE1523384C

DE1523384C - Stabilized temperature control circuit

Info

Publication number: DE1523384C
Application number: DE19651523384
Authority: DE
Inventors: Kurt Dipl Ing Reebs Hans Jürgen 8000 München Kupka
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1965-09-30
Filing date: 1965-09-30
Publication date: 1973-06-14

Description

Verstärkers, an sich bekannt, wie dies z. B. aus den nachfolgenden Literaturstellen, »Siemens Zeitschrift«, Mai 1964, Heft 5, Seiten 369 bis 375, bezüglich der Kaltleiter oder der Zeitschrift für Instrumentenkunde, 1963, Heft 5, S. 123, für Zenerdioden oder der TF-Sammlung, Beilage für Funktechnik, 1958, Nr. 22, für die Gleichstromgegenkopplung, zu entnehmen ist. Aus keiner der Literaturstellen ist jedoch die der Erfindung zugrundeliegende Anordnung zu entnehmen, durch die insgesamt eine Thermostatregelschaltung erhalten wird, bei welcher die Auswirkung der Stromverstärkungsstreuung der Transistoren beliebig herabgesetzt werden kann. Es ist möglich, die Verstärkung hinreichend konstant zu halten, so daß die Exemplarstreuungen der Regelverstärkung den Regelfehler nur noch unwesentlich beeinflussen können. Auch kleine Terhperaturänderungen lassen sich mit dieser Schaltungsanordnung sicher ausregeln. Sehr vorteilhaft wirkt sich hierbei weiterhin die Verwendung eines keramischen Kaltleiters als temperaturabhängiger Widerstand aus, da dieser hinsichtlich seines Temperaturbeiwertes besonders günstig ist. Amplifier, known per se, as z. B. from the following references, "Siemens Zeitschrift", May 1964, issue 5, pages 369 to 375, regarding the PTC thermistor or the journal for instrument technology, 1963, issue 5, p. 123, for Zener diodes or the TF collection, supplement for radio technology, 1958, No. 22, for the DC negative feedback, can be found. From none of the references however, the arrangement on which the invention is based can be seen through which a total of one Thermostat control circuit is obtained in which the effect of the current gain dispersion of the Transistors can be reduced arbitrarily. It is possible to keep the gain sufficiently constant hold, so that the sample variance of the control gain only insignificant the control error can influence. Even small temperature changes can be made with this circuit arrangement regulate safely. The use of a ceramic also has a very advantageous effect here PTC thermistor as a temperature-dependent resistor, as this is particularly favorable in terms of its temperature coefficient.

An Hand des Ausführungsbeispiels nach der Figur wird die Erfindung näher erläutert.The invention is explained in more detail using the exemplary embodiment according to the FIGURE.

An den beiden Klemmen einer Gleichspannungsquelle liegt in Serie mit einem Widerstand R₆ eine Temperaturfühler R₇, der als keramischer Kaltleiter Brückenschaltung, deren Zweige einerseits von dem ausgebildet ist, und dem ohmschen Widerstand R_& und andererseits den beiden Zenerdioden D₁ und D₂ gebildet werden. Im Nullzweig der Brücke liegt die Basis-Emitter-Strecke des Transistors T₃, wobei der Emitter an den Verbindungspunkt zwischen den beiden Zenerdioden und die Basis an den Verbindungspunkt zwischen Widerstand R₈ und Temperaturfühler R₁ geführt ist. Der Kollektor des Transistors T₃ ist über den Widerstand R₅ an die Basis des Transistors T₂ geführt, dessen Emitter mit der Basis vom Transistor T₁ verbunden ist. In der Emitter-Basis-Streckc der Transistoren T₁ und T₂ liegen die ohmschen Widerstände R₁ bzw. /?., und im Kollektorkreis die am positiven Pol der Spannungsquelle liegenden Widerstände R₂ bzw. /?₄. Der Widerstand R₂ dient dabei gleichzeitig als Heizwiderstand für den Thermostaten. Die Serienschaltung von Emitter-Kollektor-Strecke des Transistors T₁ und Widerstand R₂ liegt parallel zur Spannungsquelle. In die Schaltung sindAt the two terminals of a DC voltage source, in series with a resistor R _{6, there is} a temperature sensor R ₇ , which is formed as a ceramic PTC resistor bridge circuit, the branches of which are formed on the one hand by the, and the ohmic resistor R _& and on the other hand the two Zener diodes D ₁ and D ₂ will. The base-emitter path of the transistor T ₃ is located in the neutral branch of the bridge, the emitter being led to the connection point between the two Zener diodes and the base to the connection point between resistor R ₈ and temperature sensor R ₁ . The collector of the transistor T ₃ is led through the resistor R ₅ to the base of the transistor T ₂ , the emitter of which is connected to the base of the transistor T ₁ . In the emitter-base-Streckc of the transistors T ₁ and T ₂ are the resistances R ₁ and /?., And in the collector circuit resistances R lying on the positive pole of the voltage source ₂ and /? _4th The resistor R _{2 also} serves as a heating resistor for the thermostat. The series connection of the emitter-collector path of the transistor T ₁ and resistor R ₂ is parallel to the voltage source. Are in the circuit

ίο außerdem zwei Gegenkopplungswiderstände eingefügt. Der eine ist in Serie geschaltet zu der Zenerdiode D₂, welche am positiven Pol der Spannungsquelle liegt, und der andere liegt parallel zu der Serienschaltung des mit seiner Emitter-Basis-Strecke im Nullzweig der Brücke liegenden Transistors Τ_Λ und den kollektorseitig angeschlossenen Transistoren T₁ und T₂. Letzterer Widerstand ist an die Verbindungspunkte zwischen Zenerdiode D₂ und Gegenkopplungswiderstand/?₁₂ einerseits und Kollek-ίο also inserted two negative feedback resistors. One is connected in series with the Zener diode D ₂ , which is connected to the positive pole of the voltage source, and the other is connected in parallel with the series connection of the transistor Τ _Λ with its emitter-base path in the zero branch of the bridge and the transistors T connected on the collector side ₁ and T ₂ . The latter resistance is at the connection points between Zener diode D ₂ and negative feedback resistor /? ₁₂ on the one hand and collective

ao tor von Transistor T₁ und Widerstand R₂ andererseits geführt. Der Verstärkungsverlust, welcher durch die Gegenkopplung (R₁₁ und R₁₂) bewirkt wird, wird durch den zusätzlichen Transistor T₄ gedeckt, welcher zwischen dem Widerstand R₅ und demao gate of transistor T ₁ and resistor R ₂ on the other hand. The gain loss, which is caused by the negative feedback (R ₁₁ and R ₁₂ ) is covered by the additional transistor T ₄ , which is between the resistor R ₅ and the

Transistor T₂ angeordnet ist, und zwar liegt die Basis am Widerstand R₅ und der Emitter an derTransistor T _{2 is} arranged, namely the base is on the resistor R ₅ and the emitter on the

is des Transistors T₉. In'· seiner Emitter-Basis^: Strecke ist der Widerstand R₉ und kollektorseitig'iier" Widerstand R₁₀ angeordnet. Bei Temperatyrähderun-is of the transistor T ₉ . The resistor R _{9 is} arranged in its emitter base ^: path and the resistor R _{10 on the collector side.}

gen ändert sich entsprechend der Kennlinie des temperaturabhängigen Widerstandes der Brückenstrom, und damit nehmen die Potentiale von Emitter und Basis des Transistors T₃, die bei abgeglichener Brücke auf gleicher Höhe liegn, verschiedene Werte an; der Transistor T₃ öffnet. Der nun im Brückenzweig fließende Strom wird in den weiteren Transistoren verstärkt, so daß im Heizwiderstand R₀ ein entsprechend höherer Strom zum Fließen kommt. Über die Widerstände R₁₁ und R_v, erfolgt die Gegenkopplung. gen changes according to the characteristic curve of the temperature-dependent resistance, the bridge current, and thus the potentials of the emitter and base of the transistor T ₃ , which are at the same level when the bridge is balanced, take on different values; the transistor T ₃ opens. The current flowing in the bridge branch is amplified in the other transistors, so that a correspondingly higher current flows in the heating resistor R _0. The negative feedback takes place via the resistors R ₁₁ and R _v.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

In addition, there are specimen variations in the Tran claim: sistor of the DC amplifier. cannot be compensated. In addition, in this arrangement as

Stabilized temperature control circuit with temperature-dependent resistance combining an NTC thermistor Wheatstone-5 powered by direct voltage, which, however, because of its high temperature bridge, in one of the branches of the bridge a PTC coefficient and its continuously changing character and an NTC resistor as a temperature sensor has adverse effects on the stability of the for the inside and outside temperature of a circuit.

Thermostats are connected and in their measuring Another temperature controller, which serves to control the diagonal input of a negative feedback io of a heating current and which is also a DC amplifier, whose load resistance bridge has, in one of which there is a diagonal position a heating winding of the thermostat, the input is gonal a direct current amplifier characterized in that two Hegt is described in the patent specification 6365 of the office for Er-Zener diodes (D 1, D 2) with a series resistance and patent system in East Berlin, stood (R 12) in the other branch of the bridge - 15 With this arrangement, the switches are stabilized and that a negative feedback bridge voltage with a glow lamp (R 11) is provided between the amplifier output, which, however, is significantly worse than the Zener-Zener diode (D 2) and the series resistor diodes and also an un more favorable power balance (R 12) is switched. 20 has. In this arrangement, a negative feedback is also provided, but the negative feedback is routed via the heating resistor.

. However, this has the consequence that the negative feedback

becomes heavily load-dependent and thus the stability effect achieved is partially canceled out again.

The invention relates to a stabilized T & m- A main problem with all control circuits-for temperature control circuit with a thermostat to be continuously controlled with direct voltage consists in any case, fed Wheatstone bridge, in one of which there is a PTC bridge because of the specimen joy. and an NTC resistor due to fluctuating current amplification of the Tranais temperature sensors for the internal and external 30 sistors of the circuit as well as when exchanging temperature of a thermostat and transistors within a circuit differences in their measurement diagonals result in the input of a control error and a tendency to oscillate , coupled DC amplifier, whose load both are extremely uncomfortable for the control resistance is a heating coil of the thermostat. and undesirable phenomena affecting the control-Such control circuits are known. 35 Influence the process unfavorably. Since increasing Ver-So is, for example, in the German industry Strengthening of the control amplifier the tendency to oscillate in utility model document 1 884 498, in particular FIG. 3, enlarged, should, if possible, to avoid a stabilized control circuit arrangement for control oscillations, the control thermostat should be designed with a Wheatstone bridge amplifier so that it was written at the highest possible level. The bridge contains two temperature-dependent resistors, which act as thermal sensors inside. When using transistor specimens inside the thermostat and with a small current gain, the input of a direct current error then rises in the rule of their measuring diagonal. In addition to a dependency of the vibration amplifier lies. On the other diagonal there is also a supply voltage supplied by the control amplifier, and the heating 45 such from the temperature sensor, namely increases with the winding of the thermostat is arranged in the output circuit of its steepness and the size of the thermal time amplifier. constant the tendency to control oscillations. However, this circuit arrangement has the following disadvantages, which also involve the above, that the supply voltage at the bridge is more or less unstabilized, so that supply voltage 5 ° stick, but it is not possible, in particular fluctuations in the Bridge adjustment received. to regulate small temperature changes safely.
In addition, it is the object of the invention to create a control circuit of alternating transistors for thermostats, with which the, which is a significant disadvantage in particular small temperature changes, can be safely regulated with regard to the influence of the sample variance on 55.

has the rule error. 'To solve this problem, the stabilized

A similar control arrangement with the same temperature control circuit according to the invention der-

Another disadvantage is the German design that two Zener diodes with one

1 129 314. Series resistance in the other bridge branch

In the German Auslegeschrift 1 106 999 a 6 ° is switched and that a negative feedback resistor

Temperature controller with transistors described, between the amplifier output and the Verin particular for automatic heating control connection point between one Zener diode and

is used in railway vehicles. When the series resistor is connected.

This arrangement consists of the also existing Although there are individual measures of the arrangement

Wheatstone bridge in two branches of diodes, 65 according to the invention, such as the an

however, a corresponding stabilized effect can be "used" from PTC thermistors for control purposes or the

since it is not about Zener diodes, in this case Zener diodes are used for stabilization

Arrangement can also not be achieved. Above or the negative feedback of a direct current