METHOD AND ARRANGEMENT FOR THE POWER SUPPLY OF AN INDUCTION HEATING DEVICE
First Claim
1. A method for operating a power supply of an induction heating device having an alternating supply voltage and a frequency converter with first and second switching means provided for said power supply, wherein an operating frequency of said switching means or said frequency converter remains the same during a half-wave of said supply voltage, wherein a pulse width of a control device of said switching means or said frequency converter is modified during said half-wave such that during a first half of said half-wave a pulse width or an on-time of said first switching means is made shorter and a pulse width or an on-time of said second switching means is made longer, wherein said pulse widths or said on-times of said first and second switching means are of equal length during a second half said half wave.
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Accused Products
Abstract
In order to increase the power of an induction heating device or in order to avoid system reactions when driving the latter, either the pulse widths of the two switching means can be made unsymmetrical in the case of half-bridge driving up to the half-point of a half-cycle. Alternatively, a dead time between the pulse width can be extended. This advantageously takes place without interruption and continuously. In the course of a half-cycle, the power is thus reduced given an unaltered operating frequency and an inductor current has virtually an ideal sine-wave form.
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Citations
13 Claims
- 1. A method for operating a power supply of an induction heating device having an alternating supply voltage and a frequency converter with first and second switching means provided for said power supply, wherein an operating frequency of said switching means or said frequency converter remains the same during a half-wave of said supply voltage, wherein a pulse width of a control device of said switching means or said frequency converter is modified during said half-wave such that during a first half of said half-wave a pulse width or an on-time of said first switching means is made shorter and a pulse width or an on-time of said second switching means is made longer, wherein said pulse widths or said on-times of said first and second switching means are of equal length during a second half said half wave.
- 7. A method for operating a power supply of an induction heating device, receiving an alternating supply voltage, said power supply having a frequency converter with a switching means comprising a first and second switching means each generating a plurality of pulses of equal pulse width, wherein an operating frequency of said switching means or said frequency converter remains the same during a half-wave of said supply voltage, wherein said pulse width of said plurality of pulses are shortened with longer dead times between them, none of said switching means being controlled during said dead times.
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13. A power supply of an induction heating device comprising:
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a frequency converter having a resonant circuit with an induction coil; a resonant circuit capacitor and a half-bridge with a switchable switching means; and a control device configured to control the switching means at an operating frequency, wherein the control device is configured to modify the pulse widths or dead times in such a way to produce a constant operating frequency wherein at one pulse width is shortened or one dead time lengthened during a half cycle of an input supply voltage frequency.
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Specification