Method and arrangement for harmonic-wave suppression for AC voltage-operated PTC heaters
First Claim
1. A method for harmonic-wave suppression in AC voltage-operated PTC heaters, in which the harmonic waves are compensated by superimposing with a generated current inverted relative to a harmonic wave component, comprisinggenerating a correction current by means of an ohmic resistor in a correction current circuit arranged in parallel to said PTC heater included in a load current circuit,wherein said correction current is modulated for suppressing a third harmonic of a heating current current of said PTC heater and superimposed additively;
- wherein an instantaneous value of a voltage of said load current circuit is used for modulating the correction current in a correction current circuit.
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Abstract
The invention relates to a method and to an arrangement for harmonic-wave suppression in AC voltage-operated PTC heaters, especially in frequency-stable and frequency-variable alternating-voltage networks in aerospace applications. The problem of harmonic-wave suppression for AC voltage-operated PTC heaters, in which the harmonic waves are suppressed by superimposing a correction current, which permits a simple and economical generation of the harmonic-wave suppression signal, is solved according to the invention by generating a correction current in a correction current circuit arranged parallel to the PTC heater using an ohmic resistor (4). The correction current is generated and additively superimposed exclusively for suppressing the third harmonic of the heating current of the PTC heater.
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Citations
10 Claims
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1. A method for harmonic-wave suppression in AC voltage-operated PTC heaters, in which the harmonic waves are compensated by superimposing with a generated current inverted relative to a harmonic wave component, comprising
generating a correction current by means of an ohmic resistor in a correction current circuit arranged in parallel to said PTC heater included in a load current circuit, wherein said correction current is modulated for suppressing a third harmonic of a heating current current of said PTC heater and superimposed additively; wherein an instantaneous value of a voltage of said load current circuit is used for modulating the correction current in a correction current circuit. - View Dependent Claims (2, 3, 4)
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5. An arrangement for harmonic-wave suppression in AC voltage-operated PTC heaters, in which a PTC heater is arranged in a load current circuit of an alternating-voltage source, comprising
a correction current circuit arranged parallel to the PTC heater having an ohmic resistor for generating a controllable correction current, and a current modulator adjusted by means of a resistor for generating controllable correction current, such that a third harmonic of a heating current of the PTC heater is suppressed.
Specification