Power supply with reduced second harmonic
First Claim
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1. A power supply for supplying power to a load circuit intended to operate at a design frequency or within a design frequency range including:
- an input for alternating current;
rectifier means for converting the alternating current at the input to direct current; and
inverter means for supplying said direct current to a parallel resonant load circuit, said power supply characterised by including;
means for reducing amplitude of at least a second harmonic of a fundamental frequency of a current output by said inverter to produce a treated power signal; and
means for filtering said treated power signal, said filter means having a roll-off frequency at least approximately equal to the design frequency or a frequency in the design frequency range of said load circuit.
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Abstract
A power supply receives an alternating current which is converted by a fixed rectifier to a direct current. The direct current is converted by an inverter to an alternating current of a desired frequency and provided to a parallel resonant fixed load circuit such as a work-coil of an induction heater. The power supply includes a device for reducing amplitude of at least a second harmonic of a fundamental frequency of the current output by the inverter so that a filter connected to the load circuit can have a roll-off frequency close to the design frequency of the load circuit.
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Citations
28 Claims
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1. A power supply for supplying power to a load circuit intended to operate at a design frequency or within a design frequency range including:
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an input for alternating current; rectifier means for converting the alternating current at the input to direct current; and inverter means for supplying said direct current to a parallel resonant load circuit, said power supply characterised by including; means for reducing amplitude of at least a second harmonic of a fundamental frequency of a current output by said inverter to produce a treated power signal; and means for filtering said treated power signal, said filter means having a roll-off frequency at least approximately equal to the design frequency or a frequency in the design frequency range of said load circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of supplying power to a load circuit intended to operate at a design frequency or within a design frequency range, said method including steps of:
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receiving alternating current; converting said alternating current to direct current; supplying said direct current to a parallel resonant load circuit by means of an inverter, said method characterised by including steps of; reducing amplitude of at least a second harmonic of a fundamental frequency of a current output by said inverter to produce a treated power signal; and filtering said treated power signal, said filtering having a roll-off at least approximately equal to the desired frequency or a frequency in the design frequency range of a load circuit. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification