EP1126591A2 - Method and device for controlling or regulating power of low ohmic heating resistors - Google Patents

Abstract

The power regulation method uses an IGBT-module (10) and a choke coil (L) in series with the heating resistance (R), a capacitor (C) across the mains voltage rectifier (11) and a regulation device (16) supplied with the operating current and voltage for the current circuit of the heating resistance via a sensor device (14), for providing a control frequency for the IGBT-module. The output of the sensor device is supplied via a current limiter (18) to a driver (20) for controlling the IGBT-module. Also included are Independent claims for the following: (a) a power regulation device for a low-ohmic heating resistance; (b) an application of a power regulation device for metal, molybdenum silicide and silicon carbide heating resistance elements; (c) an application of a power regulation device for low-ohmic heating resistances for workpiece warming, paint drying, soldering, or a food cooking or clothes pressing appliance.

Description

The invention relates to a method for controlling or regulating the power from low-resistance consumers whose nominal voltage is less than that Mains voltage is, according to the preamble of claim 1 and Arrangement for this according to the preamble of patent claim 5.

When switching on and or regulating the performance of consumers with ohmic resistances occur undesirable effects on the Supply network based on how strong one-time and / or periodically recurring Current fluctuations that cause interference to others via the network Lead consumers.

This is particularly disturbing with ohmic loads with a positive Temperature coefficient. A simple example of this is light bulbs, which have a very low resistance when cold. Since the Filament temperature, however, rises very quickly, and with it the resistance increases, the network disturbance is only minor and extremely short Duration. However, this behavior is more unpleasant with a permanent Brightness control by a so-called leading edge control, such as with a dimmer, e.g. with a TRIAC. Here a so-called "network hum" occurs, which is caused by attenuators must be counteracted, e.g. consist of a magnetic core, surrounded by a live conductor. This creates however, a loss of performance with heat generation.

However, this is more difficult and more complex for household and commercial appliances with larger services such as for hot plates, irons and Ironing machines, infrared heaters and baking and industrial ovens with Resistance sheizelements.

Also have metallic heating resistors from heat treatment furnaces a positive temperature coefficient. Here, however, there is Problem of slow heating, which can take many minutes, so that the current must be limited for the duration of the heating. The Heating time increases with the specified final temperature, however can be up to 2000 ° C.

The known heating resistors have another characteristic Silicon carbide: With these the temperature coefficient can be determined by a Set of U-shaped curves depicting the specific resistance is shown above the temperature. The minimum is around 1020 ° C. In addition, the course of these curves changes with aging of the heating resistors, namely by a factor of 4 towards one Increase.

These changes in resistance have to go through with each heating process become, so that the performance in the phases of lower specific Resistance must be limited.

A well-known way to regulate or limit output consists in the use of variable transformers, which - depending on the power - are heavy and expensive.

Another known option for power control is the Use of thyristors in phase control or pulse group operation work. However, the described network faults are expressed here through flicker effects, harmonics, apparent and reactive powers.

• Frequenzumrichter,
• unterbrechungsfreie Stromversorgungen,
• Mikrowellenöfen,
• induktiven Heizungen (Induktionsöfen),
• Kraftfahrzeugzündungen.

Also known are so-called IGBT modules (Insulated Gate Bipolar Transistor Modules), which are used as switching elements, but are not in themselves suitable as linear amplifiers (manual from SEMIKRON, "Power Electronics / Power Electronics '99", pages A-182 up to A-194, section 6. "SEMITRANS ® IGBT modules"). The previous applications are limited to:

• Frequency converter,
• uninterruptible power supplies,
• Microwave ovens,
• inductive heaters (induction furnaces),
• Automotive ignitions.

U.S. Patent Nos. 3,913,002, 4,472,672, 5,006,975 and 5 942 882 it is known to consumers with rectified mains voltage to operate through expensive variable transformers and mains disturbances To avoid harmonics caused by the leading edge control periodic activation of the current within each half-wave be generated. It is also said to be expensive interference suppressors such as inductors and capacities are reduced in size.

In all cases it is a matter of regulating the power factor (High power factor) by distributing short periodic current pulses, which have a frequency several times higher than that of the mains voltage, over the entire half-waves. For this purpose, the mains voltage Control pulses corresponding to high frequency obtained with Setpoints are compared. In consumer circuits there are current sensors whose output signals match the setpoints be compared to the known leading edge controls to be controlled according to the power requirement. That to consumers applied voltages are however never recorded and closed Control purposes are used because the consumers are designed for mains voltage are.

For regulating the performance of low-resistance heating resistors, whose nominal voltage is significantly lower than the mains voltage, are the known arrangements neither provided nor suitable, because here a current-voltage transformation must be monitored. With these Heating resistors, which can have a very high output, are trading are examples of rods made of molybdenum disilicide or silicon carbide be operated with nominal voltages from, for example, 10 volts and whose ohmic resistances either have a very steep positive temperature coefficient own or age during the period of operation, whereby their ohmic resistances quadruple, for example. For example, the super heating elements from the Kanthal company Cold molybdenum disilicide has a resistance value that is only about 1/16 of the resistance value at operating temperature. The Supply of mains voltage to such a cold heating element comes So practically a short circuit, which leads to the destruction of the switching elements can lead to significant network disturbances due to current peaks and Harmonics.

The professional world has already made several claims regarding high-performance heating Silicon carbide heating rods unsuccessfully tried the usual transformers save and instead control via a thyristor controller with phase control. But about aging heating elements by a factor of 4 compared to the nominal resistance To be able to compensate for the new condition, must have a voltage reserve be taken care of in the order of factor 2. This means that when the heating elements are new, only half the voltage is required. Around to get the required performance, however, flows twice the effective Electricity compared to an aged heating element. The amplitude course of the current, however, is larger by a factor of 4. With an aged The heating element with the same power output is then full Supply voltage on, and the simple nominal current flows. If So in the aged condition of the heating elements with the supply voltage 230 volts is indicated, this means that the heating elements are in new condition can be operated with a maximum of 115 volts and twice the nominal current have to.

However, the mode of operation described above requires a very large one Control angle when operating with phase control Thyristor controller. What such large drive angles on harmonics with it can be determined using Fourier analyzes: It can be seen that considerable due to the large phase shift of the 1st harmonic Blind tax benefits are required. These blind tax benefits result at ongoing additional costs when operating such systems. This is further to notice that when the control intervenes, the phase angle changes continuously and thus also the spectrum of harmonics. However, compensation is extremely difficult.

Therefore, the professional world has switched back to the conventional one Solution with variable transformers with multiple taps to grab.

The invention is therefore based on the object, a control method and to provide an arrangement for this, with which the performance is low Heating resistors whose nominal voltage is lower than the mains voltage, without transformers and with the least possible effort can be controlled continuously or quasi-continuously without inadmissible network faults occur.

The solution to the problem is the one specified at the beginning Method by the features in the characterizing part of patent claim 1 and in the arrangement specified at the beginning by the features in the license plate of claim 5.

This completely solves the task, i.e. it a control method and an arrangement therefor are specified with the performance of low-resistance heating resistors, their nominal voltage is lower than the mains voltage, without using transformers and continuously or quasi-continuously with the least possible effort can be regulated without impermissible network disturbances occur.

It became surprising and contrary to the opinion of relevant experts found that this is actually possible in practice.

In particular, the heating power or the current consumption can be lower Heating resistors, for the operating voltages between 10 and 230 volts are needed without variable transformers and / or be managed. Instead, an IGBT can be used as the power semiconductor that have a lower saturation voltage than a bipolar transistor and has acceptable switching losses at operating frequencies above 10 kHz, for example from 20, 50 kHz and above having. Furthermore, controllability is just as easy as in MOS devices. The electricity drawn from the network at least gives way no longer significantly dependent on the sinus shape,

With the integration of control, protection and diagnostic functions A chip or circuit board will make it possible to switch power semiconductors manufacture that are practically indestructible. This means that GTOs or Thyristors are successfully replaced, their control significant is more difficult and complex, the subject of the invention has one high dielectric strength, enables high current density, simple Controllability and good short-circuit strength. Smoothing capacitors can be designed to be significantly smaller, as they cannot pass through pulsed charging currents are heavily used. It doesn't have to oversized interference filter can be used more. The Power losses are significantly lower, resulting in lower thermal Loads on the semiconductor elements. A so-called PFC (Power factor control) becomes redundant due to the subject matter of the invention; it happens automatically.

In the case of metallic resistance heating elements, a short circuit can be caused by Exclude switching on. The mains current is directly proportional to the required Power. Silicon carbide heating elements can also be used Achieve compensation for the aging process over years (!). When switching there is no inductive control reactive power when the heating elements are new. This is a significant reduction in operating costs of such a facility possible. With short-wave infrared panel radiators, such as in paint shops and in plastic thermoforming and used in soldering processes, there is no excessive current amplitude when switching.

Even if the nominal voltage of the heating elements is only a fraction of the Mains voltage, the sinusoidal mains current always results from the required power divided by the mains voltage of the power supply. If e.g. Heating elements with an operating voltage of If 115 volts are operated, these heating elements can be operated without a transformer operate directly on the network. If the nominal current of the named Heating elements is 50 A, the network only 25 A sinusoidal Deprived of electricity. The resistance characteristics of the heating elements does not matter. The subject of the invention is not subject to wear, has a high positioning speed, better efficiency, small Dimensions and light weight when compared to classic Actuators such as transducers and variable transformers are compared.

This is justified in more detail as follows: The regulation is carried out by Detection of both the flowing through said heating resistors Currents as well as the voltages applied to the heating resistors, the result is not electricity, but essentially one Power regulation.

It is a target-actual value comparison via an integrator. An externally specified setpoint "w", e.g. from the exit of a Temperature controller, compared with the actual power to be controlled. A subordinate control can be achieved in this way. The entirety of Measures and means are ultimately responsible for you at least approximately sinusoidal current profile in the network, Um current peaks in the network current to minimize in the area of the zero crossings of the mains voltage, the sinusoidal input current is corrected. The reduction the current peaks in the area of the zero crossings is determined by the Targeted masking of the control pulses of the IGBT achieved without this - in contrast to the prior art - the curve shape of the mains voltage to be used as a benchmark. The control of the IGBT driver takes place via a comparator which has a triangular voltage of for example compares 20 kHz with the voltage of the integrator.

It should be emphasized that the sinusoidal current profile of the Automatically adjusts the input current without the mains input voltage is required as a reference variable. As a result, the small transformers to be found at the state of the art at the entrance and rectifier.

By building a cascaded control (current peak value control, RMS control and ultimately power control) is e.g. an ohmic load is built up with the Kanthal super heating elements. The means the longer a current through the Heating elements flows, the more the heating element heats up and the more its resistance increases.

Since the power P = I ² x R, the furnace power only increases with the increase in the resistance value R. So that the furnace output does not increase immeasurably and the heating elements are finally destroyed, the transition from a current control to a power control is of considerable advantage.

Current peaks in the network, as in conventional phase control systems can no longer be ascertained in the subject of the invention on: Rather, the current peaks are also during the cold start phase always far below the nominal current, so that gentle mains operation is possible.

There is a particular advantage over phase control with thyristors by saving operating costs for the Tax reactive power. Since the input current is at least essentially is sinusoidal and in phase with the input voltage, the network at least predominantly only active power.

The subject of the invention has an extremely high positioning speed, better efficiency, smallest possible dimensions and a light weight if you meet these criteria with classic actuators compares. By using the subject matter of the invention, it is at age-sensitive heating elements possible for the first time, both in the network Always take the same current from new as well as from aging. The mains current remains constant with regard to the output load the shape and the amplitude at least approximately the same and sinusoidal.

Since the amplitude of the mains current is determined solely by the power of the Given the load as well as the voltage at the load, the Subject of the invention also for short-wave infrared radiators. Arise neither when switching on nor during operation in the lower setting range excessive current amplitudes in the network. In all cases the mains current is always sinusoidal and directly proportional to the power drawn.

• die Steuerfrequenz zwischen 10 und 100 kHz gewählt wird,
• die Induktivität der Drossel zwischen 0,2 und 1,0 mH gewährt wird,
• die Kapazität des Kondensators zwischen 10 und 100 µF gewählt wird,
• die Sensoreinheit für die Erfassung des Betriebsstromes über einen Strombegrenzer dem Treiber aufgeschaltet ist,
• der Verbraucherstromkreis einen Spannungsabgriff aufweist, der über eine Leitung dem Treiber zur Spannungsbegrenzung aufgeschaltet ist, und/oder, wenn
• der Komparator der Regelanordnung einen Freqenzgenerator für die Erzeugung einer Steuerfreqenz zwischen 10 und 100 kHz mit Dreiecksimpulsen besitzt.

It is particularly advantageous if, in the course of further refinements of the invention - either individually or in combination -:

• the control frequency is chosen between 10 and 100 kHz,
• the inductance of the choke is granted between 0.2 and 1.0 mH,
• the capacitance of the capacitor is chosen between 10 and 100 µF,
• the sensor unit for detecting the operating current is connected to the driver via a current limiter,
• the consumer circuit has a voltage tap which is connected to the driver for voltage limitation via a line, and / or if
• the comparator of the control arrangement has a frequency generator for generating a control frequency between 10 and 100 kHz with triangular pulses.

The invention is particularly suitable for use in the Power regulation of ohmic consumers from the group of Resistance heating elements made of metals and silicon carbide and for Power regulation of ohmic consumers for heating purposes of workpieces in industrial ovens, for drying paints, for deforming plastics, for soldering and for household and Commercial appliances for cooking food and ironing textiles.

An embodiment of the subject matter of the invention is as follows explained in more detail with reference to FIGS. 1 to 5:

Figur 1

den Verbraucherstromkreis mit den zugehörigen Sensor- Regeleinrichtungen,

Figur 2

den Verlauf der Netzspannung nach Gleichrichtung über drei Halbwellen,

Figur 3

den prinzipiellen Verlauf des Netzstromes über eine Halbwelle der Netzspannung,

Figur 4

die Funktion des Komparators und

Figur 5

zu Zwecken des Vergleichs ein Diagramm mit einer Kurvenschar für den temperaturabhängigen Netzstromverlauf, wie er bei einem Molybdändisilizid-Heizstab auftritt, wenn dessen Heizleistung mittels einer klassischen Phasenanschnittsteuerung durch einen Thyristor gesteuert wird.

Show it:

Figure 1

the consumer circuit with the associated sensor control devices,

Figure 2

the course of the mains voltage after rectification over three half-waves,

Figure 3

the basic course of the mains current over a half-wave of the mains voltage,

Figure 4

the function of the comparator and

Figure 5

For the purpose of comparison, a diagram with a family of curves for the temperature-dependent line current curve, as occurs with a molybdenum disilicide heating rod, if its heating power is controlled by a thyristor using a classic phase control.

In Figure 1, the core of the control arrangement is a commercially available one IGBT module 10 of the type described above, the a current input 1, two current outputs 2 and 3 and two control voltage terminals 6 (for the gate voltage) and 7 (for the emitter voltage) owns. In the consumer circuit there are - in series - the ohmic Consumer R, which also consists of a parallel connection of several Consumers can exist, and an inductive choke L. The mains voltage inputs are labeled L1, N and PE. The mains voltage inputs L1 and N are a rectifier 11 with a positive terminal 12 and a negative terminal 13 connected. Parallel to the rectifier 11, a capacitor C is connected. The load circuit on which An example of a voltage of 230 volts is with reinforced lines highlighted. Due to the action of the inductor L, the load current i do not jump up suddenly and also not suddenly to zero become.

The inductor L and the capacitor C are designed to be AC voltage-proof but as small as possible in accordance with the largest possible consumer current, for example the inductor L between 0.2 and 1.0 mH, preferably with 0.5 mH, and the capacitor C between 10 and 100 μF, preferably with 50 µ F. The preferred values apply to an industrial furnace with a current consumption of 70 A.

The current input 1 is a sensor unit 14 for detecting the Upstream of consumer current; in it the measured current 1 in converted a proportional voltage U across a return line 15 of a control arrangement 16 is connected. A voltage tap 17 leads via a current limiter 18 and a line 19 a driver 20 with electrical isolation. In the current limiter 18, the maximum operating current can be set to a predetermined value.

The voltage applied to the consumer R is via lines 21 and 22 tapped and fed to a potential isolator 23, which is exemplary contains an optocoupler. Another return line leads from this 24 to control arrangement 16. Current, voltage or power control (i or u) can alternatively be added, whereby the Switches are not shown for the sake of simplicity. Furthermore, the Control arrangement 16 via a setpoint generator, not shown adjustable setpoint w applied.

The control arrangement 16 includes an integrator 25, at the output 26 of which a variable voltage u1, u2, .... un, is present, which is a comparator 27 is activated. Its output 28 is in turn connected to driver 20. From this lead two lines 29 and 30 to the control voltage terminals 6 and 7 of the IGBT module 10. The function of the control arrangement 16 is explained in more detail below with reference to FIGS. 3 and 4 explained. The driver 20 serves as an amplifier with potential isolation. On the Line 29 can - based on line 30 - a voltage between +18 volts and -5 volts are present.

A branch line 31 leads from line 22 to driver 20. This measure, one that is not absolutely necessary but advantageous is used Safety function, namely the monitoring of the collector voltage. For example, a shutdown when the collector voltage is a predetermined Limit of e.g. Exceeds 7 volts (short-circuit monitoring).

Figure 2 shows the course of the mains voltage with a frequency of exemplary 50 or 60 Hz after rectification over three half-waves, whereby the dashed curve for the second half-wave the voltage curve implies without rectification. By rectification this half wave "flipped" to the other side of the abscissa (with time t). The rounded areas 31 are on the action of the capacitor C. attributed.

Figure 3 shows the principle of control over a half-wave of the mains voltage U (50 or 60 Hz) and the associated current i. In the comparator 27 is a jagged curve according to Figure 4 with a frequency of generated 20 kHz as an example. This so-called triangular voltage is with the variable voltage of the integrator 25 compared. It turns on Output of the comparator 27 an on-off duty cycle for the IGBT 10th on. The wavy curve shows the actual current curve with the specified one Frequency of 20 kHz (control frequency) between the current curves io and iu on a very coarser scale. First the current curve rises according to the voltage and the consumer resistance R steep until the IGBT module 10 switches off again, whereby the actual Current curve again approaches the lower current curve iu. With their When reached, the IGBT module 10 switches on again, and the actual one Current curve rises again, whereupon the game according to the Control frequency repeated any number of times. The current curves io and iu are in depends primarily on the control frequency and the inductance of the Throttle L.

Figure 4 shows the course of the voltage U according to the function of the comparator 27 with the control frequency already mentioned by way of example 20 kHz. U1 and u2 are the specifiable control voltages at the output 26 of the integrator 25 in dashed lines. The below the triangles, ie between t0 and t1 or between t1 and t2 The lines for u1 and u2 indicate the switch-off status of the IGBT module 10, the intermediate sections (above the triangles) its on state. The switch-off times are each with "a", the Switch-on times labeled "e". The proportions of these sections indicate the respective proportional outputs at the consumer R, which range from 0% (at the tips of the triangles) to 100% (at the bases of the triangles) can be varied.

The design of the choke L depends on the control frequency of the Comparator 27: The higher this is, the smaller L can be chosen. So it may be desirable to control the frequency of the To increase compensator 27 to over 20 kHz, for example in the direction to 100 kHz, the switching frequency of the IGBT module 10 corresponding is increased.

When the IGBT module 10 is switched on, the current flows from the positive pole of the Rectifier 11 via the choke L and the consumer R to the current input 1 of the IGBT module 10, on to current output 2 and Negative pole of the rectifier 11. When the IGBT module 10 is switched off, it flows the current continues via current output 3 and also via the Choke L and the consumer R. It is in the manner described possible, the current flow through the consumer R and at this applied voltage almost lossless but in any case without reaction to regulate (on the network). With an oven output of 10 to For example, 20 kW results in a power loss of around 0.3 kW is discharged via a cooling block. Have capacitor and choke very small dimensions and weights, which are noticeable in total are lower than the comparable values of a variable transformer. The cost is correspondingly lower. That way it is for example possible low voltage heating elements with voltages from 10 to 120 volts compared to a mains voltage of, for example 230 volts are to be operated with the advantages mentioned.

FIG. 5 shows a comparison of the mains current curve using a diagram, as it occurs with a molybdenum disilicide heating element, if its Heating power using a classic phase control a thyristor is controlled. The abscissa extends over a half wave, and on the ordinate are the factors "F" from 0 to 16 for the current draw plotted against the nominal current at operating temperature, where the factor 1 stands for this nominal current.

A group of sinusoidal curves is shown, of which the top (F = 15) applies to the course of the current consumption in the cold state and the lowest for the course of the current consumption at operating temperature. The curves in between show - from top to bottom - current consumption curves with increasing intermediate temperatures. The points on the curves indicate the switch-on times, the two hatched Areas to the right of the normals on the abscissa mark the proportional power supply in two cases. It can be seen that the Switch-on times brought forward with increasing temperatures be that, however, the entire half wave only when the Operating temperature (bottom curve, F = 1) in the entire control range can be driven through. In all other cases there are high ones Harmonic components and high tax reactive power.

Reference symbol list:

1

Current input

2nd

Current output

3rd

Current output

6

Control voltage terminal

7

Control voltage terminal

10th

IGBT module

11

Rectifier

12th

positive terminal

13

negative terminal

14

Sensor unit

15

Return line

16

Control arrangement

17th

Voltage tap

18th

Current limiter

19th

management

20th

driver

21

management

22

management

23

Isolators

24th

Return line

25th

Integrator

26

output

27

Comparator

28

output

29

management

30th

management

31

Areas

a

Switch-off times

c

capacitor

e

Switch-on times

i

electricity

io

upper current curve

iu

lower current curve

L

throttle

L1

Mains voltage input

N

Mains voltage input (zero phase)

PE

Mains voltage input (ground)

R

Consumer resistance

t

time

t0, t1, t2

Times

w

Setpoint

Claims (13)

Method for controlling or regulating the output of low - resistance heating resistors (R), the nominal voltage of which is less than the mains voltage, by means of rectified alternating current through semiconductor components, characterized in that a) an IGBT module (10) is used as the semiconductor element b) a choke (L) is arranged in the circuit of the heating resistor and in series with this, c) a capacitor (C) is arranged in parallel with a rectifier (11) used for rectifying the mains voltage, d) the power factors operating current (i) and operating voltage (U) are detected in the circuit of the heating resistor (R) and fed to a control arrangement (16), e) in the control arrangement (16) by means of an integrator (25) a comparison of a target value (w) for the operating current (i) and the operating voltage (U) is carried out, the input signal of a comparator (27) being broken down into a sequence of pulses whose frequency is used as the control frequency for the IGBT module (10) and is a multiple of the mains frequency, a sensor unit (14) for the operating current (i) in the circuit of the IGBT module (10) and the heating resistor (R). arranged and furthermore the operating voltage (U) of the heating resistor (R) is tapped and fed back to the control arrangement (16), and the output of the sensor unit (14) via a current limiter (18) to a driver (20) for controlling the IGBT module ( 10) is activated, and that f) the deviations between the target value (w) and the sequence of pulses in accordance with the respective sign of the deviations are used to control the IGBT module (10). Method according to Claim 1, characterized in that the control frequency is chosen between 10 and 100 kHz. Method according to claim 1, characterized in that the inductance of the choke (L) is granted between 0.2 and 1.0 mH. Method according to claim 1, characterized in that the capacitance of the capacitor (C) is chosen between 10 and 100 µF. Arrangement for controlling or regulating the power of low-resistance heating resistors (R), the nominal voltage of which is less than the mains voltage, with a rectifier (11) for generating rectified alternating current through semiconductor components, characterized in that a) the semiconductor element is an IGBT module (10), b) the power factors operating current (i) and operating voltage (U) can be recorded in the circuit of the heating resistor (R) and can be supplied to a control arrangement (16), c) in the circuit of the IGBT module (10) and the heating resistor (R) a sensor unit (14) for the operating current (i) is arranged, and that the output of the sensor unit (14) of the control arrangement (16) for controlling the IGBT Module (10) is switched on. d) the operating voltage (U) of the heating resistor (R) can be tapped and returned to the control arrangement (16), e) a choke (L) is arranged in the circuit of the heating resistor (R) and in series therewith, f) a capacitor (C) is arranged in parallel with a rectifier (11) used for rectifying the mains voltage, g) in the control arrangement (16) an integrator (25) is arranged, by means of which a comparison of a setpoint (w) for the operating current (i) and the operating voltage (U) can be carried out, the input signal of a comparator (27) into a Sequence of pulses can be dismantled, the frequency of which is a multiple of the mains frequency and is applied to the IGBT module (10) as a control frequency via a driver (20), and that h) in the control arrangement (16) deviations including their sign between the target value (w) and the sequence of pulses can be determined, the output of the control arrangement (16) via the driver (20) to the IGBT module (10) for its control is activated. Arrangement according to claim 5, characterized in that the control arrangement is designed for a control frequency between 10 and 100 kHz. Arrangement according to claim 5, characterized in that the inductance of the choke (L) is designed between 0.2 and 1.0 mH. Arrangement according to claim 5, characterized in that the capacitance of the capacitor (C) is designed between 10 and 100 µF. Arrangement according to claim 5, characterized in that the sensor unit (14) for detecting the operating current (i) is connected to the driver (20) via a current limiter (18). Arrangement according to claim 5, characterized in that the IGBT (10) has a voltage tap which is connected to the driver (20) for voltage limitation via a line (31). Arrangement according to claim 5, characterized in that the comparator (27) of the control arrangement (16) has a frequency generator for generating a control frequency between 10 and 100 kHz with triangular pulses. Use of the arrangement according to claim 5 for the power control of low-resistance heating resistors (R) from the group of Resistance heating elements made of metals, molybdenum disilicide and Silicon carbide. Use of the arrangement according to claim 5 for the power control of low-resistance heating resistors (R) for the purpose of Heating workpieces in industrial ovens for drying of paints, for deforming plastics, for soldering and for Household and commercial appliances for cooking food and Ironing textiles.

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