High frequency heating generator having an improved matching network between a tetrode amplifier and a resonant circuit
First Claim
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1. A high frequency heating generator, comprising:
- an amplifier having an input and an output, the output being connected to a resonant circuit that is electromagnetically coupled to a part to be heated;
a controlled frequency oscillator, connected to said amplifier, having an output terminal for outputting a high frequency signal to the input of the amplifier, wherein the amplifier includes at least one tetrode having a control gate; and
means for measuring a phase shift between a current output from said tetrode to the resonant circuit and a voltage across a pair of terminals of the resonant circuit, and for modifying the frequency signal output by the oscillator as a function of said phase shift, the means for measuring said phase shift having a first input connected to the control gate of the tetrode and a second input connected to the terminals of the resonant circuit.
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Abstract
A high frequency heating generator which includes an electron tube amplifier, the output of which is connected to a resonant circuit that is electromagnetically coupled to a part to be heated, and a controlled frequency oscillator. The oscillator outputs a high frequency signal to the input of the amplifier. It also includes circuitry to measure the phase shift between the current output to the resonant circuit and the voltage at its terminals, and to modify the frequency of the oscillator as a function of this phase shift. The invention can be applied notably to devices for heating by electromagnetic induction, dielectric losses or plasma.
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14 Claims
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1. A high frequency heating generator, comprising:
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an amplifier having an input and an output, the output being connected to a resonant circuit that is electromagnetically coupled to a part to be heated; a controlled frequency oscillator, connected to said amplifier, having an output terminal for outputting a high frequency signal to the input of the amplifier, wherein the amplifier includes at least one tetrode having a control gate; and means for measuring a phase shift between a current output from said tetrode to the resonant circuit and a voltage across a pair of terminals of the resonant circuit, and for modifying the frequency signal output by the oscillator as a function of said phase shift, the means for measuring said phase shift having a first input connected to the control gate of the tetrode and a second input connected to the terminals of the resonant circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification