Abstract: A variable frequency RF power delivery system is used with a control system that adjusts the output frequency of the RF power delivery system. Frequency adjustments are made so as to maintain the required input current and input voltage within the capabilities of the input current and input voltage source.

Abstract: An induction heating system having an induction source, a heating element heated from the induction source and a circuit energized by the induction source. The circuit can be a controller which includes a temperature sensor for measuring a temperature of the heating element, and a feedback loop formed between the temperature sensor and the induction source. The heating element can be mounted within a housing to form an induction heated container for holding items to be heated. Such a container can be used in commercial food warming and holding.

Abstract: An RF power supply that is capable of tracking rapid changes in the resonant frequency of a load and capable of quickly responding to varying load conditions so as to deliver the desired amount of power. The present invention also provides an RF power supply capable of delivering a wide range of power over a broad frequency range to a load that is remotely located from the power supply.

Abstract: A radio frequency (RF) power system for providing RF power to a load. The RF power system comprises a tank circuit; a direct current (DC) voltage source that provides a DC voltage within a first predetermined range; an amplifier, coupled to said DC voltage source, to provide an alternating voltage to said tank circuit; a frequency controller, coupled to said amplifier, to control a frequency of said alternating voltage provided by said amplifier; and a power sensor being coupled to said tank circuit for providing a signal to said frequency controller, wherein said frequency controller controls said frequency of said alternating voltage based on said signal provided from said power sensor.

Abstract: An induction heating power supply is disclosed. It includes a power circuit having at least one switch and a power output. The output circuit includes an induction head. The output circuit is coupled to the power output. A controller has at least one feedback input connected to the output circuit, and has a control output connected to the switch. The controller predicts the switch zero crossing and preferably soft switches the switch. Current feedback is obtained from a coil placed between the bus bars. Each bus bar is comprised of multiple plates to increase current capacity.

Abstract: An RF power supply that is capable of tracking rapid changes in the resonant frequency of a load and capable of quickly responding to varying load conditions so as to deliver the desired amount of power. The present invention also provides an RF power supply capable of delivering a wide range of power over a broad frequency range to a load that is remotely located from the power supply. According to one embodiment, the RF power supply includes a direct current (DC) voltage source that provides a DC voltage within a predetermined.

Abstract: An RF power supply that is capable of tracking rapid changes in the resonant frequency of a load and capable of quickly responding to varying load conditions so as to deliver the desired amount of power. The present invention also provides an RF power supply capable of delivering a wide range of power over a broad frequency range to a load that is remotely located from the power supply.

Abstract: According to the invention, the rear end of a preceding metal piece and a front end of a succeeding metal piece are heated, pressed and joined prior to the finishing hot rolling. An alternating magnetic field running through the metal pieces in the thickness direction thereof is generated in an end region on opposed faces of the respective metal pieces to perform heating. Another alternating magnetic field whose direction is reverse with respect to that of the former alternating magnetic field is partially generated in the end region on the opposed faces of the metal pieces and in either a region where the metal pieces exist or a region outside width ends of the metal pieces. This assures a uniform heating of the end region on the opposed faces of the metal pieces over their full width to reliably join the both metal pieces to each other.

Abstract: The present invention relates to an induction heating apparatus for heating an image on a recording material which has an electric conductor, a first coil, for inducing an eddy current in the electric conductor disposed over a longitudinal direction of the electric conductor, a second coil disposed so as to overlap an end portion of the first coil, a first power supply for supplying an alternating current to the first coil, a second power supply for supplying an alternating current to the second coil, a phase shifting circuit for controlling a phase of the alternating current supplied to the second coil, and control means for controlling the phase shifting circuit in conformity with a temperature of the electric conductor.

Abstract: An induction furnace having a voltage source series inverter, a load circuit having a combination of an induction coil and a resonating capacitor bank, and control circuitry to phase lock the inverter frequency to the natural resonant frequency of the load. The capacitor bank can be divided into two groups, one across the output of the inverter and the other in series with the load. This arrangement allows for the division of the inverter voltage across the furnace coil according to the ratio of the two capacitances. The inverter uses pulse width modulation and is buffered from the load circuit by means of a small series connected inductor. Additionally, the system can have a common power supply system that supplies power in any desired proportion to a plurality of induction furnaces.

Abstract: A high-frequency inverter having a simple circuit construction capable of executing a constant-frequency operation and a zero-volt switching operation and an induction heating cooker using the high-frequency inverter are disclosed. The high-frequency inverter is comprised of an inverter circuit for converting a direct current from a DC power source into a high-frequency current and a control circuit for controlling the inverter circuit. The inverter circuit is comprised of: a one-transistor inverter constructed of a heating coil whose one terminal is connected to one terminal of a DC power source, a first switching element connected in series between the other terminal of the heating coil and the other terminal of the DC power source, and a first resonance capacitor connected so as to form a resonance circuit with the heating coil; and a series circuit connected in parallel with the heating coil and constructed of a second switching element and a second resonance capacitor.

Abstract: An induction heating fixing apparatus is disclosed which in characterized by comprising an object to be heated formed of an electroconductive material, a coil for effecting induction heating on the object to be heated, an inverter circuit for effecting the flow of a high frequency to the coil, a thermistor for detecting the temperature of the object to be heated, a control circuit electrically insulated from the inverter circuit and adapted to control the inverter circuit based on the temperature detected by the thermistor so as to keep the object to be heated at a temperature in a prescribed range, and an insulating switch for transmitting the control signal from the control circuit in an electrically insulated state to the inverter circuit.

Abstract: An arrangement for the control of electrically controllable appliances, particularly electric cookers proposes for each cooking point an operating element magnetically held in contactless manner on the top or front of a plate, e.g. a glass ceramic plate. Below or behind the plate is located a magnet, which magnetically secures the operating element, which can in this position be rotated in contactless manner sensors are operated, which are used for changing the control of the cooking point. Both the control and the fixing of the operating element take place in contactless manner. The plate requires no openings, passages, depressions, etc. The operating elements can be removed on overcoming the magnetic holding force. This removal can be utilized for the complete disconnection of the cooker.

Abstract: Circuits for high frequency energy supply for cooking pots, etc. utilize resonant circuits in which the coil for the energy transfer forms a part. Furthermore circuits of the inverter type are used. It has turned out to be advantageous to use an extra circuit which gives the current feed from the rectifier of the power supply unit to the inverter a period of oscillation which is less than or equal to the period of oscillation of the resonant circuit. In this manner an efficient control of the supplied power is obtained, and the losses are reduced. Furthermore measuring signals may be derived which may be used for increasing the safety with respect to incorrect use.

Abstract: A ripple current generator for an induction heating apparatus includes a resonant circuit with a current injecting self-inducting coil (6), a capacitor (13), an induction heating coil (14) and a high-frequency controlled power switch (12). The current injecting self-inducting coil (6) is saturable and mounted in series with a parallel assembly consisting of two arms; a first arm (B.sub.1) containing the switch (12) and a second arm (B.sub.2) containing a capacitor (13) mounted in series with the induction heating coil (14). The self-inducting coil includes a magnetic circuit that automatically reaches saturation during the resonance phase of the oscillating circuit. The generator is useful in household cooking appliances such as induction plates, cookers or deep fryers, as well as industrial induction heating equipment for treating metal components.

Abstract: A delay timer incorporated into an induction cooking cartridge permits the use of the induction cooking cartridge with conventional modular cooktops including bi-metal power switches without damage to the induction circuitry.

Abstract: The present invention relates to an induction type heat fixing device. In the induction type fixing device, a high frequency current is supplied to a coil by switching an electric current supply to coil between a supply state and an interrupted state so that an induction current is generated in a fixing roller (heat-receiving member). The high frequency current is controlled in accordance with at least one of the voltage fluctuation of the electric power source, the amount of coil current and the coil voltage.

Abstract: A welding power supply that includes a series resonant converter, including at least one switch and at least one capacitor is disclosed. The converter includes a switching circuit including an enable input. A voltage sensing circuit that determines the earliest safe switching time of the switch is provided. The safe switching time is the time that will prevent a peak voltage on the capacitor from exceeding a predetermined threshold for a next cycle of the converter. The voltage sensing circuit provides an enable signal to the enable input when the earliest switching time has passed, to enable the switching circuit. A pair of welding output terminals connected to the series resonant converter receives the output. A controller including a curve shaper, for providing a constant current output in the welding range is also disclosed. The controller also provides an adaptive hot start that provides varying amounts of energy in response to the welders skill.

Abstract: A high-frequency power supply which is primarily intended for use with an inductive heating apparatus. The high-frequency power supply has a pre-regulator for emitting a constant output voltage, an inverter for generating a constant output voltage, and an output network for amplifying the constant output voltage and converting the constant output voltage to a high-frequency constant output current. The power supply disclosed generates a very high frequency ac output, drives a wide range of possible loads, minimizes root mean square input current for a given output power, and can be powered from a wide range of input power sources.

Abstract: Quality welds are highly dependent upon achieving appropriate temperatures everywhere along the bond line. The present invention uses multinode thermocouples to measure the bond line temperature in real time and to provide control signals for the moving coil (welding head).

Abstract: The present invention relates to an induction heating cooker for supplying a predetermined resonant current to a heating coil to thereby carry out a cooking operation, the induction heating cooker including: a rectifying unit for full wave rectifying a commercial alternating current, a zero voltage detecting unit for detecting a zero potential of the commercial alternating current, a control unit for synchronizing with the zero potential of the commercial alternating current detected by the zero voltage detecting unit to thereby control the overall operations of the induction heating cooker, a variable frequency oscillating unit for receiving a control signal generated by the control unit to thereby generate an oscillating frequency, an inverter driving unit for generating a driving signal to thereby drive the switching element according to the oscillating frequency generated by the variable frequency oscillating unit, an inverter for receiving the direct current voltage generated from the rectifying unit acc

Abstract: A process for induction hardening a part to a desired depth with an AC signal applied to the part from a closely coupled induction coil includes measuring the voltage of the AC signal at the coil and the current passing through the coil; and controlling the depth of hardening of the part from the measured voltage and current. The control system determines parameters of the part that are functions of applied voltage and current to the induction coil, and uses a neural network to control the application of the AC signal based on the detected functions for each part.

Abstract: In order to determine the contents of solids in a heated elongated slug of thixotropic metal having a longitudinal axis, there is an apparatus comprising an inductive heating coil with electrical winding. Moreover, a sensor includes at least one measuring coil arranged between the heating coil and the slug. This sensor provides an output signal which corresponds to the contents of solids demanded.

Abstract: In a switching device of an induction heating cooker, an oppositely poled diode for conducting a reverse current is coupled across the collector-emitter portion of a switching element provided in the first switching device, and turn-ON operation of the switching devices does not OCCUR in normal operation of the DUTY FACTOR T.sub.2 /T.sub.1 .apprxeq.0.5.

Abstract: An inverter power control circuit for a high-frequency heating apparatus of a half-bridge type which comprises an inverter.

Abstract: In a method for open-loop/closed-loop control of current converter valves of at least two load-guided parallel oscillating circuit inverters being supplied from a common direct current or direct voltage source and being connected in series on the DC side, each inverter has one induction furnace with a compensating conductor. Two diagonally opposed current converter valves are ignited at a time in one inverter to establish a flow of current from the source with a series-connected choke through the parallel oscillating circuit connected to that inverter. Load phase angles of the parallel oscillating circuit inverters are adjusted, resulting in arbitrarily specified individual powers of the parallel oscillating circuits wherein a maximum power that can be output by the source is taken into account, and attaining a specified ratio between the individual powers of the parallel oscillating circuits.

Abstract: An induction heater comprises a coupled pair of inverters and an induction head for generating heat, coupled to the second inverter. The output signal of the first inverter which operates at a fixed frequency, is controlled by feedback indicative of the heat output of the induction head. A control circuit processes the feedback information to compensate for power losses in the induction head. The output of the first inverter is electrically coupled to the input of the second inverter, which operates at an adjustable frequency which is selected by the user to optimize heating. The power delivered to the induction head is dependent on the output voltage of the second inverter, which is dependent on the output signal of the first inverter.

Abstract: A resonance circuit including a high frequency induction heating coil is set to a resonance state and a heating temperature of an object to be heated (for example, catalytic converter or the like) is controlled on the basis of a resonance frequency varied with an increased temperature of the object under the resonance state.

Abstract: A monitor device for creating a current signal having a voltage representative of the instantaneous alternating current in an induction heating coil connected to an alternating current supply by two closely spaced, parallel input conductors separated by a narrow gap or flux package through which flows the flux created by the alternating current in the parallel conductors. The monitor device comprising: a multiturn sensing winding, means for securing the winding between said parallel conductors and over the flux passage whereby the flux flowing through flux passage intersects the turns of the sensing winding, and means for creating the current signal by the induced voltage in the winding.

Abstract: A domestic cooking system including a base defining one or more cooking locations, electromagnetic induction apparatus for heating a food at the cooking location and apparatus for automatic stirring of the food at the cooking location.

Abstract: In a system of supplying electric power to an induction furnace, a required heating power is directly supplied to the induction furnace from an ac synchronous generator driven by a prime mover, such as a diesel engine, via a single-phase coil. At the same time, the voltage to be supplied to the single-phase coil is rendered continuously variable by an automatic voltage regulator of the generator to render continuously variable the heating power corresponding to the voltage to be supplied, and the frequency of the voltage to be supplied is rendered continuously variable by an automatic frequency regulator of the prime mover in accordance with predetermined mutual relationships with the voltage to be supplied. In addition, at the start of power supply, the voltage to be supplied and the frequency thereof are increased with gradients for a predetermined time duration from their predetermined minimum values to their rated values in accordance with the predetermined mutual relationships.

Abstract: An induction heater comprises a coupled pair of inverters and an induction head for generating heat, coupled to the second inverter. The first inverter operates at a constant frequency, but the total output current is controlled through pulse width modulation. The output current is rectified and provided as a DC input voltage, proportional to the total output current of the first inverter, to the second inverter. The second inverter operates at an adjustable frequency which is selected by the user to optimize heating. The power delivered to the induction heater is dependent on the output voltage of the second inverter, which is dependent on the input voltage to the second inverter, and the output current of the first inverter.