Power supply with reduced second harmonic
AssigneeCheltenham Induction Heating Limited of Phoenix Works
InventorsHaroon Karamat Sheikh, Philip Lipscomb, Michael Richard Leonard
Life of this patent
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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.
Claims28
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.
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:
- 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.
Dependencies are inferred from the claim text.