Apparatus for power control by phase gating and a method for harmonic reduction
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Abstract
The invention relates to an apparatus for power control by phase gating of an AC voltage, which supplies an electrical load (14), and for reduction of harmonics which are created by the phase gating, in particular up to a region of 4 kHz, preferably in the region of the third harmonic, having a first circuit element (12) (TRIAC) which is connected in series with the load (14) and is driven by a control device (20) in order to carry out phase gating. The apparatus is distinguished in that a second circuit element (34) is provided in series with a resistance element (32), with the series circuit being arranged in parallel with the first circuit element (12) and with the control device (20) being designed such that it drives the second circuit element (34) shortly before the first circuit element (12) and switches it to the on state for a short time period. The invention also relates to a method for harmonic reduction in the range up to 4 kHz, preferably of the third harmonic, for power control by phase gating.
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Citations
22 Claims
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1-9. -9. (canceled)
- 10. An apparatus for power control by phase gating of an AC voltage, which supplies an electrical load, and for reduction of harmonics which are created by the phase gating, in particular up to a region of 4 kHz, preferably in the region of the third harmonic, having an electric motor as the load, having a first circuit element (TRIAC) which is connected in series with the load and is driven by a control device in order to carry out phase gating, and having a resistance element, wherein a second circuit element is provided in series with the resistance element, with the series circuit being arranged in parallel with the first circuit element and with the control device being designed such that it drives the second circuit element shortly before the first circuit element and switches it to the on state for a short time period and in that the resistance element is arranged in an air flow which is produced by the electric motor in order to cool it.
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21. A method for harmonic reduction in the range up to 4 kHz for power control of an electric motor by phase gating, having the following steps:
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a first circuit element is driven on the basis of a first selected trigger angle in order to carry out a phase gating process, a connection which bridges the first circuit element and has a resistance is switched on briefly at a time before the triggering of the first circuit element, and the connection which has a resistance is cooled by the electric motor. - View Dependent Claims (22)
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Specification