Abstract: Disclosed herein is an induction-heating cooking apparatus that includes a sensing circuit for controlling an output of a heating coil, and more specifically, to an induction-heating cooking apparatus capable of enhancing accuracy in measuring electric currents of a heating coil by simply modifying a circuit. The induction-heating cooking apparatus includes a control unit calculating an output of a heating coil on the basis of electric currents measured by a sensor supplying alternating current power.

Abstract: A cooking apparatus and a control method thereof, and more particularly, technology for determining the type of vessel placed in the cooking apparatus and controlling power in response to a state change of the placed vessel or a temperature change of a coil. In accordance with one aspect, a cooking apparatus includes: a coil on which a vessel is placed, configured to form a magnetic field upon application of a current; a detection sensor configured to detect a magnitude of an input current applied differently according to a type of the vessel and a magnitude of an input voltage of the cooking apparatus; and a controller configured to determine a type of the placed vessel according to a power value calculated based on the detected input current and input voltage, and to determine a heating mode of the cooking apparatus based on the determined type of vessel.

Abstract: A power supply circuit with a novel structure is provided.

Abstract: Method for operating an apparatus for wirelessly transferring energy in the direction of an electrical consumer by means of inductive coupling, wherein the apparatus comprises: a rectifier for generating a DC voltage from a power supply system voltage, an inverter fed from the DC voltage and configured to generate a pulse-width-modulated drive signal, and a coil driven by means of the pulse-width-modulated drive signal, by means of which coil an alternating magnetic field is generatable for the purpose of transferring the energy, wherein the method comprises the following steps: controlling an electrical actual power output by the inverter to a predefinable electrical target power, wherein a frequency and a duty cycle of the pulse-width-modulated drive signal serve as manipulated variables of the control, wherein the following steps are carried out for the purpose of adjustment to the target power: a) setting a start frequency (f_0), b) setting a start duty cycle (DC_1) in such a way that the target power

Abstract: An induction heating device includes a working coil and a resonance capacitor, an inverter that performs a switching operation to supply a resonance current to the working coil, a plurality of snubber capacitors electrically connected to the inverter, a direct current (DC) link capacitor electrically connected to the inverter, and a relay configured to electrically connect one of the plurality of snubber capacitors to the DC link capacitor or the resonance capacitor.

Abstract: An image heating device includes a heater that includes a heating resistor; a rotatable tubular film in which the heater is provided in an inner space of the rotatable tubular film; a roller; and an electrification control portion configured to perform wave number control by changing the ratio of electrification ON to electrification OFF for each set control cycle. In the image heating device F1, relations tON?? and tOFF?? are satisfied, where tON represents a longest continuous electrification period in electrification patterns in which electrification is turned both on and off in the control cycle, tOFF represents a longest continuous shutoff period in the electrification patterns, and ? represents a time constant of thermal conduction with the shortest distance from the heating resistor to a contact surface of the heater that is in contact with the film.

Abstract: An induction heating apparatus includes a working coil; an inverter configured to perform switching operation to thereby apply a resonance current to the working coil; and a controller configured to provide a control signal with a fixed frequency to the inverter to thereby control the switching operation. The controller changes a pulse width of the control signal based on a predetermined cycle that is set based on a temperature of the inverter.

Abstract: An induction heating device includes first and second working coils connected electrically in parallel, an inverter unit configured to switch at least one of the first working coil or the second working coil, an inverter driving unit connected to the inverter unit; a first semiconductor switch connected to the first working coil, a first semiconductor switch driving unit connected to the first semiconductor switch, an over-current protection unit connected to the first semiconductor switch, configured to generate information based on a current that flows in the first semiconductor switch, and configured to, based on the information, determine whether to turn off the inverter driving unit, and a control unit that is configured to receive the information, and determine, based on the information, whether to block a pulse signal to the inverter driving unit and whether to turn off the first semiconductor switch driving unit.

Abstract: A portable induction heating tool includes a housing which includes a base having a support surface. The support surface defines a recess facing away from the housing. The recess is at least partially defined by a wall projecting from the support surface. A work coil is within the housing and secured to the base in a location aligned with the recess. The portable induction heating tool includes electronic circuitry which is configured to provide oscillating electrical energy to the work coil, thereby generating an oscillating magnetic field projecting away from the base. The electronic circuitry is also configured to detect a quantity of energy consumed by the work coil and to limit the quantity of energy to a predetermined quantity.

Abstract: Disclosed is a charging apparatus capable of reducing a low-frequency leakage current, the charging apparatus including a duty controller that determines a duty of a switching element in a power factor correction converter based on a level of a common-mode component of an alternating-current (AC) voltage of AC power provided from an external charging facility, a level of a direct-current (DC) voltage formed by a DC link capacitor, and a leakage current flowing from a connection node of two input-terminal Y-capacitors and a connection node of two output-terminal Y-capacitors to the ground.

Abstract: An induction heating device providing a support plate with an upper surface for receiving a side face of a bearing. A plurality of concentrically arranged induction coils provided at an underside of the support plate, and connected to and selectively powered by a generator. Temperature sensors arranged on the upper surface of the support plate at different radial distances from a center axis of the concentric coils. A control unit receives and monitors a temperature signal from each of the temperature sensors, which receives and processes a signal indicative of a load on each coil, when selectively powered, to identify a first coil that is electromagnetically coupled to an inner ring and a second coil that is electromagnetically coupled to an outer ring. The control unit configured to select a first and a second temperature sensor associated with the first and second coils respectively, and to execute a heating cycle.

Abstract: Disclosed is a method for controlling a power supply of a high-frequency heating device, comprising: controlling a switching element of the high-frequency heating device to operate according to a control signal with a preset duty ratio; detecting a real-time current flowing through the switching element; and if the real-time current is greater than or equal to a preset current reference value, controlling the switching element to turn off, and controlling the switching element to turn on when a next turn-on window of the control signal comes. The method may reduce a maximum current during an operation of the switching element, thus reducing requirements for the switching element and enabling an effective over-current protection. Further disclosed is an apparatus for controlling a power supply of a high-frequency heating device and a high-frequency heating device with the apparatus for controlling the power supply.

Abstract: Disclosed are an electromagnetic heating device and a heating control circuit thereof, and a low power heating control method. The heating control circuit comprises: a voltage zero-crossing detection unit for detecting a voltage zero-crossing signal of an alternating current power source; a resonance heating unit; a rectification and filtering unit; a power switch tube; a drive unit, connected to a drive end of the power switch tube to drive the power switch tube to be turned on and off; a drive voltage transformation unit, connected to the drive end of the power switch tube to change a drive voltage of the power switch tube; and a main control unit for controlling the power switch tube to operate under the drive of a first drive voltage according to the voltage zero-crossing signal, thereby reducing the damage risk of the power switch tube and reducing turn-on noises.

Abstract: A system and methods for controlling the fuser heater of an electrophotographic imaging device, including initiating a preheating operation for preheating the fuser heater. Following a temperature of the fuser heater reaching a first predetermined temperature during the preheating operation, heater power is calculated based on a current temperature of the fuser heater and upon a second predetermined temperature. Current line voltage of a power supply line powering the electrophotographic device is also calculated, and a maximum heater power is determined based on the calculated current line voltage. The calculated heater power is then compared with the determined maximum heater power and the fuser heater is powered using the heater power equal to a lesser of the calculated heater power and the determined maximum heater power to heat the fuser heater from the first predetermined temperature to a second predetermined temperature.

Abstract: A system and methods for controlling the fuser heater of an electrophotographic imaging device, including initiating a preheating operation for preheating the fuser heater. Following a temperature of the fuser heater reaching a first predetermined temperature during the preheating operation, heater power is calculated based on a current temperature of the fuser heater and upon a second predetermined temperature. Current line voltage of a power supply line powering the electrophotographic device is also calculated, and a maximum heater power is determined based on the calculated current line voltage. The calculated heater power is then compared with the determined maximum heater power and the fuser heater is powered using the heater power equal to a lesser of the calculated heater power and the determined maximum heater power to heat the fuser heater from the first predetermined temperature to a second predetermined temperature.

Abstract: A system and methods for controlling the fuser heater of an electrophotographic imaging device, including initiating a preheating operation for preheating the fuser heater. Following a temperature of the fuser heater reaching a first predetermined temperature during the preheating operation, heater power is calculated based on a current temperature of the fuser heater and upon a second predetermined temperature. Current line voltage of a power supply line powering the electrophotographic device is also calculated, and a maximum heater power is determined based on the calculated current line voltage. The calculated heater power is then compared with the determined maximum heater power and the fuser heater is powered using the heater power equal to a lesser of the calculated heater power and the determined maximum heater power to heat the fuser heater from the first predetermined temperature to a second predetermined temperature.

Abstract: A household appliance power supply device and method are disclosed. The power supply device comprises a switching converter having an input filtering stage; and a determining means configured to obtain estimation data indicative of the input current that is adsorbed from the a main power input, on the base of the rate of change of the bus voltage across said bus capacitor respectively, during a second switching period. The switching converter further comprises a bus capacitor, electrically connected with at least one output terminal of a rectifying stage, a resonant tank, electrically connected with said bus capacitor, and a switching device electrically connected with said resonant tank, said switching device being operated with a switching cycle having a first switching period, and a second switching period.

Abstract: An electricity meter includes a sensor circuit, a measurement circuit, a leading PF detection circuit and a control circuit. The sensor circuit is operably connected to detect voltage and current provided to a load, and generates corresponding voltage and current measurement signals. The measurement circuit is configured to generate energy consumption information based on the voltage and current measurement signals. The leading PF detection circuit is configured to generate a first value representative of a phase difference of the current measurement signal with respect to the voltage measurement signal, and to generate a leading PF detection signal responsive to determining that the first value corresponds to a leading power factor that leads unity power factor by more than a predetermined threshold. The control circuit stores an indication in memory responsive at least in part to the leading PF detection signal.

Abstract: An induction heating fusing device and an image forming apparatuses that may control even a very small current region by tracking a resonance frequency to perform PWM control and phase control without considering a deviation of a part constant or a temperature change are provided. The induction heating fusing device includes: a serial resonance circuit having an induction coil and a condenser; a phase comparator, a phase controller, a resonance frequency tracking oscillator, and a PWM (pulse width modulation) signal generator. The phase comparator compares a phase of a pulse outputted by the PWM signal generator with a phase of current flowing through the induction coil, outputs a comparison result obtained by the comparing to the phase controller when controlling the phase, and outputs the comparison result to the resonance frequency tracking oscillator when performing PWM control.

Abstract: The purpose of the present invention is to minimize switching losses of an inverter. An induction heating device includes: a plurality of induction heating coils (20) which are disposed adjacent with each other; a plurality of inverters (30), each of which has a capacitor (40) serially connected to each of the induction heating coils (20), and converts a DC voltage into a square wave voltage; and a control circuit (15) which controls so as to align the phase of coil currents flowing though the plurality of the induction heating coils (20), wherein the control circuit (15) controls the timing at which the square wave voltage transitions such that an instantaneous value of the square wave voltage is preserved in either the DC voltage or a turnover voltage, when the coil current zero crosses.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: A method (200;300;400) for operating a cooking hob (100) is proposed. The cooking hob comprises at least a first (1151) and a second (1156) cooking zones and a control unit (135) configured for controlling the first and second cooking zones. The method comprises the following steps executed by the control unit.

Abstract: A fuel delivery system for a vehicle includes a fuel injector that dispenses heated fuel flow and controls the temperature of the heated fuel within a desired temperature range. Fuel flowing through the example fuel injector is inductively heated by a valve element sealed with the fuel flow. A driver controller detects changes in temperature by monitoring changes in parameters that vary responsive to temperature in the material of the heated element. Changes in the material responsive to temperature are utilized to tailor input into the heated element to maintain a desired temperature of the heated element and thereby the temperature of the fuel.

Abstract: An arc welding system and methods. The system is capable of monitoring variables during a welding process, according to wave shape states, and weighting the variables accordingly, detecting defects of a weld, diagnosing possible causes of the defects, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: A modular RF power system allows multiple power supplies to combine their RF output power as a single system and deliver it to a common resonant circuit. For flexibility and commonality, each power supply is designed to be separately powered by AC line voltage (aka AC Mains). The AC voltage supplied to each power supply may differ due to differing AC distribution line length, line impedance, wire gauge, or different supply generation locations.

Abstract: A boosting circuit includes a switch element, a first coil, a second coil, and a capacitor. The switch element generates a first alternating current voltage having a first frequency from a direct current voltage. The first coil generates a magnetic field around the first coil with a flow of the first alternating current voltage having the first frequency in the first coil. The first coil also induces an eddy current in the object with the magnetic field to inductively heat the object. The second coil is cumulatively connected to the first coil. The capacitor is connected to the first coil and the second coil in a parallel manner.

Abstract: A conventional induction heating cooker which operates two inverters at the same time, with only one input current detecting circuit provided, cannot measure each of input currents to each of the plurality of inverters, and cannot control input powers by feedback control on input currents. In the induction heating cooker which has a plurality of inverters, when the input power varies to the inverter which has less input power supplied, the variation hardly influences the cooking. The induction heating cooker according to the present invention fixes the operating frequency for the inverter which has less input power supplied and performs the feedback control of the input current for the inverter which has bigger input power supplied.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: An induction hob having a plurality of induction heating elements; a control unit to operate the plurality of induction heating elements so as to heat at least one flexibly definable heating zone in a synchronized manner; and a measurement array to measure a heating power generated by the plurality of induction heating elements. The measurement array measures a sum of heating powers of at least two induction heating elements and the control unit uses the sum of heating powers to regulate the heating power generated by the plurality of induction heating elements.

Abstract: An induction heat treatment method with which temperature control is enabled, condition setting is easy, and the quality of a treatment object can be stabilized includes: a data acquiring step of heating and quench-hardening a sample of the treatment object to thereby acquire process data; a storing step of storing the process data; a checking step of checking the power supply output transition data and the quenching timing data as to validity based on the temperature transition data stored in the storing step; and a mass production step of performing heat treatment of the treatment object in accordance with the power supply output transition data and the quenching timing data stored in the storing step and checked as to validity in the checking step.

Abstract: A cooking appliance. The cooking appliance includes a cook top for a kitchen. One side of the cook top includes a cooking area with cooking areas. The cooking areas may be operated via an induction cooker. The bottom side of the cooking appliance has a display. The display can provide useful information thereon such as the time. The cook top can be arranged in a first horizontal position for use of the cooking areas, and folded to a second vertical position during non use to display information on the display. The cooking appliance also includes a data reader, such as an RFID reader or bar code scanner to obtain data from a food product package. The data may include suggested recipes, cooking temperatures, and/or cooking times. The obtained data may be used to assist in controlling the operation of the cooking areas.

Abstract: An induction heating cooker includes a switch element and an inductive coil, which is coupled between a power voltage and a first terminal of the switch element. A second terminal of the switch element is coupled to a common voltage. A control circuit for controlling the inducting heating cooker includes first and second comparators and a pulse generator. The first comparator receives voltages of two terminals of the inductive coil and thus outputs a trigger signal. The second comparator receives a reference voltage and a voltage of the first terminal of the switch element, and enables a fading signal when the voltage of the first terminal is higher than the reference voltage. When the trigger signal is enabled, the pulse generator outputs a pulse to control the switch element. When the fading signal is enabled, the pulse generator reduces a pulse width of the pulse.

Abstract: A method for controlling resonant power converters using power transistors, particularly for induction heating systems, comprises a step of assessing the occurrence of non-zero voltage switching or non-zero current switching and a step of adjusting the control accordingly, the assessment of the above occurrence being performed by monitoring at least one electrical parameter correlated to the resonant circuit.

Abstract: A supplying power adjusting apparatus has excellent temperature response and excellent stabilities to power supply change and load change. The apparatus is provided with a semiconductor inverter for high-speed switching power control, which converts a direct current rectified by a rectifying circuit (10) into alternating current power in response to a control signal and supplies a heater (7) with the power; a temperature change detecting circuit (24) for detecting the temperature change of the heater (7); a power supply change detecting circuit (22) for detecting the power change of the rectifying circuit (10); a load change detecting circuit (23) for detecting the change of the alternating current power supplied to the heater (7); and a power control signal generating circuit (15) which calculates a power quantity to be supplied to the heater (7) and controls the frequency or duty ratio of a control signal to be added to the power controlling semiconductor inverter in response to the calculated results.

Abstract: An induction hob having a plurality of induction heating elements; a control unit to operate the plurality of induction heating elements so as to heat at least one flexibly definable heating zone in a synchronized manner; and a measurement array to measure a heating power generated by the plurality of induction heating elements. The measurement array measures a sum of heating powers of at least two induction heating elements and the control unit uses the sum of heating powers to regulate the heating power generated by the plurality of induction heating elements.

Abstract: This invention provides a power supply which supplies an AC electric current to the coil of a heating unit employing the electromagnetic induced heating method via a connector connecting a plurality of wires, and a method for the power supply. The method includes the steps of supplying electric currents to the coil via 1st and 2nd wires from 1st and 2nd electric current supply units and detecting feedback electric currents via 3rd and 4th wires through the coil. Whether an electric current is abnormally supplied to the coil is monitored on the basis of these detected electric currents. It is controlled in accordance with the monitoring result to stop driving the 1st and 2nd electric current supply units and supply an electric current to the coil.

Abstract: An induction heat treatment method with which temperature control is enabled, condition setting is easy, and the quality of a treatment object can be stabilized includes: a data acquiring step of heating and quench-hardening a sample of the treatment object to thereby acquire process data; a storing step of storing the process data; a checking step of checking the power supply output transition data and the quenching timing data as to validity based on the temperature transition data stored in the storing step; and a mass production step of performing heat treatment of the treatment object in accordance with the power supply output transition data and the quenching timing data stored in the storing step and checked as to validity in the checking step.

Abstract: This invention provides a power supply which supplies an AC electric current to the coil of a heating unit employing the electromagnetic induced heating method via a connector connecting a plurality of wires, and a method for the power supply. The method includes the steps of supplying electric currents to the coil via 1st and 2nd wires from 1st and 2nd electric current supply units and detecting feedback electric currents via 3rd and 4th wires through the coil. Whether an electric current is abnormally supplied to the coil is monitored on the basis of these detected electric currents. It is controlled in accordance with the monitoring result to stop driving the 1st and 2nd electric current supply units and supply an electric current to the coil.

Abstract: An induction-heating cooking apparatus and a method for operating the same are disclosed. Upon receiving a low-voltage signal in a high-output level state, the apparatus controls an output signal to allow an inverter to be operated only in a ZVS (Zero Voltage Switching) area. If an input voltage applied to a circuit is a low voltage, the apparatus compensates for the input voltage using a smaller one between a blocking voltage and an output control signal generated from the microprocessor, thereby limiting a compensation component. Therefore, the apparatus prevents the occurrence of a power loss caused by an excessive switching operation, and also prevents a switch from receiving a high instantaneous current, resulting in increased endurance of cooking appliances.

Abstract: An induction heating apparatus for a fixing device of an image forming apparatus includes a rectifying circuit for rectifying a commercial power supply, an excitation coil, a switching element for switching the supply of the output of the rectifying circuit to the excitation coil, and a switching signal output unit for outputting a switching signal for the switching element thereby supplying the excitation coil with a high frequency current. The invention limits a current supply time to the excitation coil in such a manner that the maximum output for induction heating is set according to the commercial power supply voltage, thereby reducing the first print time without a power consumption in excess of the rating.

Abstract: An inverter circuit of an induction heating rice cooker which controls a switching frequency of an inverter in a variable manner according to a variation in an input voltage and drives the inverter at the controlled switching frequency. The inverter circuit comprises a power supply circuit for rectifying and filtering a commercial alternating current (AC) voltage to supply the input voltage to the induction heating rice cooker. The inverter performs a switching operation based on the input voltage from the power supply circuit to heat the rice cooker. The inverter circuit further comprises an inverter driving circuit for outputting a drive pulse to control the switching frequency of the inverter in the variable manner according to the input voltage from the power supply circuit and drive the inverter at the controlled switching frequency.

Abstract: An induction heating device prevents an object to be heated from being displaced and buoyed from a mounting surface due to an mutual action of repulsive forces between the object to be heated and an induction heating coil. The induction heating device includes a source-current detector for detecting a source current input to a high-frequency inverter including the induction heating coil and an inverter circuit, a source-current change detector for measuring a change against time of a magnitude of the source current to detect a displacement and buoying of the object to be heated, such as a cooking pot, and a change examining unit. The controller controls an output of the high-frequency inverter in response to a detection result of the change examining unit. The induction heating device prevents the cooking pot from being displaced and buoyed even if the pot is not touched by a user at startup of heating or during the heating operation, and is inexpensive and safe.

Abstract: An induction heating apparatus can heat aluminum pot etc. with pot vibration noise being suppressed. During a turn-on time of second switching device 57, an energy is accumulated at choke coil 54, and at the same time a resonant current with a shorter period than the turn-on time of second switching device 57 or a driving time of first switching device 55 is generated at heating coil 59, so that during turn-off of second switching device 57, i.e., during on-time of first switching device 55, the energy accumulated at choke coil 54 is transferred to second smoothing capacitor 62. And then the output power is supplied from smoothing capacitor 62 to heating coil 59, thereby reducing the pot vibration noise, which is caused by pulsating current of input voltage.

Abstract: An induction heating apparatus for a fixing device of an image forming apparatus includes a rectifying circuit for rectifying a commercial power supply, an excitation coil, a switching element for switching the supply of the output of the rectifying circuit to the excitation coil, and a switching signal output unit for outputting a switching signal for the switching element thereby supplying the excitation coil with a high frequency current.

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 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 induction heater having a working coil for providing a high-frequency application of power to a sample is provided with a control circuit for controlling the amount of power to the working coil. A phase control member can be triggered to provide a first level of power to the sample to heat it below its combustion level, to thereby remove any exterior stains. Subsequently, a second level of power can be applied for a predetermined period of time to heat it to a combustion point whereby the combustion gases of the sample are free from any byproducts of the stain and an accurate measurement can be accomplished.

Abstract: A control system for controlling overshoot and undershoot power values when switching power from a single inverter power source to a plurality of inductive loads, or a single load having a plurality of zones, having different resonant frequencies. The control system causes a preselected amount of power to be drawn from the inverter power source and delivered to the loads, or zones in a time-shared manner. The control system varies the phase shift between load voltage and load current and selectably adjusts the amount of variation in response to overshoot and/or undershoot of power drawn from the inverter and delivered to a load or zone which can occur when switching between loads or zones.

Abstract: This resonant power supply produces a varying magnetic field from a resonant inductor. Two active switches drive, but remain outside, a resonant circuit, also including resonant capacitor. A phase-splitting transformer provides, via a decoupling inductor, one connection for a power supply; the return is through the active switches, which are either off or are from time to time driven alternately by the controller so as to maintain the resonant current in the resonant circuit. Applications include induction heating and induction hobs for cooking, and also a power source for inductively powered vehicles (or other inductively powered devices) adjacent to an inductive pathway.