US 6,608,291 B1 · Induction heating apparatus

Abstract

A portable induction heating system which utilizes a broadband high frequency high-power, low output impedance power generator formed from switching MOSFET devices. A voltage-controlled oscillator (VCO) or microprocessor-controlled signal generator drives a power output stage under feedback control so as to effectuate resonance at a high frequency in an induction coil assembly connected to the power generator. The power generator is operable with a switching regulator that can supply a fixed DC voltage, e.g., 12 to 48 V or a variable setpoint. The induction coil assembly includes a capacitive circuit portion connected to a conductive coil that can couple magnetic field to a susceptor. A microcontroller is provided for inputting operating parameters such as power, frequency, duty cycle and duration, and is operable to auto-tune the VCO output under feedback control by sweeping frequency at startup as well as by controlling drift during operation under a changing load.

Claims28

Dependent claims

An induction heating apparatus, comprising:

a solid state power generator capable of driving a variable impedance, said generator operating with a switching regulator for generating current at a high frequency;
an induction coil assembly connected to said solid state power generator, said induction coil assembly including a capacitive circuit portion coupled to a conductive coil, wherein said conductive coil operates responsive to said high frequency current to generate a magnetic field for inductively coupling with a susceptor, thereby substantially rapidly heating said susceptor's material;
said solid state power generator including a power output stage driven under feedback control so as to effectuate resonance in said induction coil assembly at around said high frequency;
and
said power output stage including a pre-driver circuit portion coupled to a driver circuit portion, wherein said pre-driver circuit portion comprises a plurality of buffer circuits disposed in parallel, each buffer circuit operating to drive a transformer coupled to a field effect transistor (FET) device, and said transformer and said FET device forming at least a part of said driver circuit portion.

2 more elements

A system for heating a component by inductively coupling to said component, comprising:

power generator means for generating current with a frequency at least at around 0.5 MHz;
an induction coil assembly coupled to said power generator means via connection means, wherein said induction coil assembly is resonantly operable at said frequency to couple to said component for Generating heat thereat;
said power generator means including a power output stage driven under feedback control so as to effectuate resonance in said induction coil assembly at around said frequency;
said power output stage including a pre-driver circuit portion coupled to a driver circuit portion wherein said pre-driver circuit portion comprises a plurality of buffer circuits disposed in parallel, each buffer circuit operating to drive a transformer coupled to a field effect transistor (FET) device, and said transformer and said FEN device forming at least a part of said driver circuit portion;
and
feedback control means for controlling said current's frequency so as to maintain resonance of said induction coil assembly during operation therefor.

3 more elements

A system for heating a component by inductively coupling to said component, comprising:

a solid state power generator operable without a matching transformer for generating current with a selectable frequency, said solid state cower generator including a power output stage driven under feedback control, said power output stage including a pre-driver circuit portion coupled to a driver circuit portion, wherein said pre-driver circuit portion comprises a plurality of buffer circuits disposed in parallel, each buffer circuit operating to drive a transformer coupled to a field effect transistor (FET) device, and said transformer and said FET device forming at least a part of said driver circuit portion;
an induction coil assembly coupled to said solid state power generator via connection means, wherein said induction coil assembly is resonantly operable at said selectable frequency to couple to said component for generating heat thereat;
and
feedback control means for controlling said current's frequency so as to maintain resonance of said induction coil assembly during operation thereof.

1 more element

Dependencies are inferred from the claim text.

Induction heating apparatus

Life of this patent

Induction heating apparatus

Life of this patent

Abstract

Claims28