SK279550B6 - Measuring thermoelectric transducer of electrical power - Google Patents

Measuring thermoelectric transducer of electrical power Download PDF

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Publication number
SK279550B6
SK279550B6 SK1024-91A SK102491A SK279550B6 SK 279550 B6 SK279550 B6 SK 279550B6 SK 102491 A SK102491 A SK 102491A SK 279550 B6 SK279550 B6 SK 279550B6
Authority
SK
Slovakia
Prior art keywords
resistor
transistor
thermoelectric transducer
controlled
measuring
Prior art date
Application number
SK1024-91A
Other languages
Slovak (sk)
Inventor
Mikuláš Bobík
Ladislav Grňo
Július Groch
Original Assignee
Mikuláš Bobík
Ladislav Grňo
Július Groch
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mikuláš Bobík, Ladislav Grňo, Július Groch filed Critical Mikuláš Bobík
Priority to CS911024A priority Critical patent/CS102491A3/en
Publication of SK279550B6 publication Critical patent/SK279550B6/en

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Abstract

A measuring thermoelectric transducer of electrical power consists of a resistor (1) and heat transducer (2) both situated upon a common thermally-insulated underlay (3). The resistor consists of an element whose instantaneous resistance value is electronically controllable by momentary value of an input signal. A controlled resistor based on a transistor represents a preferable solution of the invention. In that case, it is made possible to performer a simple control by means of a computing amplifier (4) in such a way that a transistor emitter is connected with an inverting input of the computing amplifier, and, the transistor's gate is connected with an input of the computing amplifier. Placing the second controlled resistor upon the common underlay to perform a substitution measuring is another preferable solution. As regards the thermal flow, a symmetric placing of two underlays (3) with the controlled resistors and heat transducers so as to compensate perturbing influences upon a measuring process is yet another preferable solution.

Description

Technical field
The present invention relates to electrical power transducers for use in measuring and control technology.
BACKGROUND OF THE INVENTION
Conventional electrical power transducers are based on the electromechanical principle of converting the mean power value, i. j. the product of the instantaneous value of voltage and current per mechanical moment of force. The disadvantage of this method of transfer is the low achievable accuracy and relatively high sensitivity to external influences. Nowadays, power converters are realized mostly on the basis of direct generation of mean value of product of quantities proportional to electric voltage and current through electronic circuits. Hall effect-based electronic multipliers and non-linear electronic-based multipliers are structurally simple, but do not allow high conversion accuracy. Substantially better properties in terms of achievable conversion accuracy have multipliers processing the instantaneous value of multiplied quantities, e.g. pulse or digital multipliers. The disadvantage of multipliers of this type is the high cost and the fact that at the current technological level of production of semiconductor devices, the maximum frequency of the input signal is in principle limited to about 200 kHz depending on the required accuracy. The achieved conversion error is of the order of 10‘3.
The most accurate measuring transducers are based on utilizing the thermal effects of electrical power. Only transducers using thermally isolated resistors with a constant resistance value are known. The disadvantage of this type of transducer is that it makes it possible to measure the power generated by either a voltage or a current signal only. Direct measurement of the power defined by a pair of independent voltage and current signals is not possible with these converters.
SUMMARY OF THE INVENTION
The thermoelectric transducer of electrical power according to the invention consists of a resistor and a temperature sensor placed on a common, thermally insulated substrate. The principle of the invention is that the resistor is formed by an element whose instantaneous resistance value is electronically controllable by the instantaneous value of the input signal.
Preferably, the controlled resistor is formed by a transistor. In this case, simple control by the operational amplifier is possible such that an inverting input of the operational amplifier is connected to the emitter of the transistor and the control electrode of the transistor is connected to the output of the operational amplifier.
The substitution measurement method is made possible by another controlled resistor placed on a common substrate, by means of which it is possible, by maintaining a constant temperature of the substrate, to compensate the measured power by the substitution power of the direct current. An advantage of this method of supplying substitution power is that, while maintaining a constant DC value, the voltage across the controlled resistor is a linear function of the measured power.
In order to minimize the effect of ambient temperature on the measurement process, it is advantageous to have two separate, in terms of heat flux from the eye, symmetrically placed, controlled resistor and temperature sensor pads in a common housing. The system located on one of the items is a measurement and the system on the other is a reference.
In order to minimize converter error due to the power required to control the transistor as a variable resistor, it is preferred that the transistor is controlled by an electric field.
The thermoelectric transducer according to the invention allows direct measurement of electrical power in a wide frequency band with low realization costs and with an accuracy comparable to that of conventional thermoelectric comparators and converters of rms value or voltage. current.
Overview of the figures in the drawing
In the accompanying drawing, FIG. 1 shows, in principle, an example of a power transducer with one controlled resistor.
In FIG. 2 shows in principle an example of a symmetrical power transducer with two controlled resistors.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, a controlled resistor formed by transistor 1 and a temperature sensor 2 are disposed on a common, thermally insulated substrate 3, the emitter of transistor 1 being connected to the inverting input of the operational amplifier 4 and the control electrode of transistor 1 being connected to the output of the operational amplifier 4. it forms the voltage input of the converter and the connection dedicated to the input of the operational amplifier 4 and the emitter of the transistor 1 forms the current input of the converter. The measured power information is recorded on the temperature sensor 2.
The converter operates by applying a voltage derived from one of the pair of input signals to the resistor and controlling the resistance of the controlled resistor 1 to control the current through the resistor so that the instantaneous value of this current coincides with the current derived from the second input signal. In this way, it is possible to impose a power defined by a mutually independent pair of voltage and current. The power dissipated in the controlled resistor 1, which is proportional to the power measured, results in a change in the temperature of the thermally insulated system formed by the resistor 1 and the temperature sensor 2 on a common thermally insulated substrate 3. The signal from the temperature sensor 2 is processed by one of the methods used in thermoelectric converters .
In FIG. 2, a further resistor formed by a transistor 6 controlled by an operational amplifier 8 is placed on a common substrate 3. The transistor 6 can thus be used to apply a substitution power to the substrate 3 by maintaining its constant temperature, i. j. The substitution power is preferably supplied either by the voltage at the collector of transistor 6 at the constant current of the emitter of the transistor or at the current of the emitter at the constant voltage of the collector.
Industrial usability
The measuring transducer according to the invention can be used in the field of the most accurate measurements of electrical power, energy, its consumption characteristics and in the field of mass production of these meters.

Claims (6)

1. A thermoelectric transducer of electrical power, consisting of a resistor and a temperature sensor, which are located on a common, thermally insulated substrate, characterized in that the resistor (1) is formed by an element whose instantaneous resistance value is electronically controllable by instantaneous value. input signal.
Thermoelectric transducer according to claim 1, characterized in that the resistor (1) is formed by a transistor
Thermoelectric transducer according to claim 2, characterized in that the resistor channel of the transistor (1) is connected to the inverting input of the operational amplifier (4) and the control electrode of the transistor (1) is connected to the output of the operational amplifier (4).
Thermoelectric transducer according to Claims 1 to 3, characterized in that a second resistor (6) formed by an element whose instantaneous value resists an electronically controllable instantaneous value of the input signal is disposed on the substrate (3).
Thermoelectric transducer according to Claims 1 to 4, characterized in that in the common housing (7) there are two disks (3) with controlled resistors and temperature sensors symmetrically placed in terms of heat flux from the surroundings.
Thermoelectric transducer according to claims 2 to 5, characterized in that the transistor (1) is controlled by an electric field.
SK1024-91A 1991-04-11 1991-04-11 Measuring thermoelectric transducer of electrical power SK279550B6 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CS911024A CS102491A3 (en) 1991-04-11 1991-04-11 Measuring thermoelectric converter of electric power

Publications (1)

Publication Number Publication Date
SK279550B6 true SK279550B6 (en) 1998-12-02

Family

ID=5343570

Family Applications (1)

Application Number Title Priority Date Filing Date
SK1024-91A SK279550B6 (en) 1991-04-11 1991-04-11 Measuring thermoelectric transducer of electrical power

Country Status (2)

Country Link
CS (1) CS102491A3 (en)
SK (1) SK279550B6 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010054811A1 (en) * 2008-11-17 2010-05-20 Rohde & Schwarz Gmbh & Co. Kg Thermoelectric power measurement cell and corresponding measurement method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010054811A1 (en) * 2008-11-17 2010-05-20 Rohde & Schwarz Gmbh & Co. Kg Thermoelectric power measurement cell and corresponding measurement method
US9194895B2 (en) 2008-11-17 2015-11-24 Rohde & Schwarz Gmbh & Co. Kg Thermoelectric power measurement cell and corresponding measurement method

Also Published As

Publication number Publication date
CS102491A3 (en) 1992-10-14

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