The present disclosure relates to an induction cooktop. The induction cooktop comprises a ceramic cooking surface in connection with a housing. A plurality of inductors is disposed in the housing and each of the inductors is in communication with an automatic control system. The automatic control system is configured to check for the presence of a cooking pan on the cooktop in order to prevent the inductors from activating in the absence of the cooking pan. The automatic control system is activated upon receiving an activation command.

A power conversion apparatus and a power conversion method are provided. The power conversion apparatus includes a rectifier configured to convert AC power to DC power, a smoothing filter configured to control the DC power received from the rectifier to be constant, an inverter configured to convert the DC power received from the smoothing filter into high-frequency power by turning the DC power on and off using a switching device, and a control unit configured to control the rectifier and the inverter. A rating of output power from the inverter is determined in accordance with a frequency of the high-frequency power output from the inverter, a current-applying time, and an operation rate obtained by dividing the current-applying time by a sum of the current-applying time and a non-current-applying time.

A power conversion apparatus and a power conversion method are provided. The power conversion apparatus includes a rectifier configured to convert AC power to DC power, a smoothing filter configured to control the DC power received from the rectifier to be constant, an inverter configured to convert the DC power received from the smoothing filter into high-frequency power by turning the DC power on and off using a switching device, and a control unit configured to control the rectifier and the inverter. A rating of output power from the inverter is determined in accordance with a frequency of the high-frequency power output from the inverter, a current-applying time, and an operation rate obtained by dividing the current-applying time by a sum of the current-applying time and a non-current-applying time.

A method of controlling an inductive heating circuit, having a varying load, to seal a packaging material is provided. The method comprises generating AC power of at least two frequencies on at least one inductor in the inductive heating circuit; determining of the resulting phase shift in the inductive heating circuit from the current generated at the at least two frequencies; determining the impedance of the inductive heating circuit for each of the at least two frequencies; determining a load characteristics of the inductive heating circuit based on the relationship between the determined impedance and the determined phase shift; determining an impedance operating range; and selecting an AC output frequency for an induction power generator based on the load characteristics which results in the least amount of phase shift from a set ideal value and which is associated with an impedance that is within the impedance operating range.

A method of controlling an inductive heating circuit, having a varying load, to seal a packaging material is provided. The method comprises generating AC power of at least two frequencies on at least one inductor in the inductive heating circuit; determining of the resulting phase shift in the inductive heating circuit from the current generated at the at least two frequencies; determining the impedance of the inductive heating circuit for each of the at least two frequencies; determining a load characteristics of the inductive heating circuit based on the relationship between the determined impedance and the determined phase shift; determining an impedance operating range; and selecting an AC output frequency for an induction power generator based on the load characteristics which results in the least amount of phase shift from a set ideal value and which is associated with an impedance that is within the impedance operating range.

An induction heating device includes a working coil, an inverter including a first switching element and a second switching element that are configured to perform a switching operation and to apply a resonance current to the working coil, a snubber capacitor including a first snubber capacitor connected to the first switching element, and a second snubber capacitor connected to the second switching element, a phase detector configured to detect a phase difference between the resonance current applied to the working coil and a switching voltage applied to the second switching element, and a controller configured to receive, from the phase detector, phase information including the phase difference, provide the inverter with a switching signal to thereby control the switching operation, and adjust an operating frequency of the switching signal based on the phase information to thereby control an output of the working coil.

An induction heating device includes a working coil, an inverter including a first switching element and a second switching element that are configured to perform a switching operation and to apply a resonance current to the working coil, a snubber capacitor including a first snubber capacitor connected to the first switching element, and a second snubber capacitor connected to the second switching element, a phase detector configured to detect a phase difference between the resonance current applied to the working coil and a switching voltage applied to the second switching element, and a controller configured to receive, from the phase detector, phase information including the phase difference, provide the inverter with a switching signal to thereby control the switching operation, and adjust an operating frequency of the switching signal based on the phase information to thereby control an output of the working coil.

Provided is a system for controlling heating of a workpiece that includes an interface to receive a target temperature (T.sub.T) for the workpiece. A processor is configured to determine, based on monitoring outputs of temperature sensor(s), a current highest temperature (T.sub.H) for the workpiece and set a control temperature (T.sub.C) based on the received target temperature and the current highest temperature. A control system is configured to heat the workpiece to substantially the control temperature (T.sub.C) by turning on a heating device, and turning off the heating device when the workpiece reaches substantially the control temperature (T.sub.C). The processor is further configured to characterize a temperature ramp rate based on a measured temperature overshoot at the workpiece after turning off the heating device, and the control system is configured to heat the workpiece to the received target temperature (T.sub.T) by controlling the heating device based on the temperature ramp rate.

Provided is a system for controlling heating of a workpiece that includes an interface to receive a target temperature (T.sub.T) for the workpiece. A processor is configured to determine, based on monitoring outputs of temperature sensor(s), a current highest temperature (T.sub.H) for the workpiece and set a control temperature (T.sub.C) based on the received target temperature and the current highest temperature. A control system is configured to heat the workpiece to substantially the control temperature (T.sub.C) by turning on a heating device, and turning off the heating device when the workpiece reaches substantially the control temperature (T.sub.C). The processor is further configured to characterize a temperature ramp rate based on a measured temperature overshoot at the workpiece after turning off the heating device, and the control system is configured to heat the workpiece to the received target temperature (T.sub.T) by controlling the heating device based on the temperature ramp rate.

A process for directional solidification of a cast part comprises energizing a primary inductive coil coupled to a chamber having a mold containing a material; energizing a primary inductive coil within the chamber to heat the mold via radiation from a susceptor, wherein the resultant electromagnetic field partially leaks through the susceptor coupled to the chamber between the primary inductive coil and the mold; determining a magnetic flux profile of the electromagnetic field; sensing a magnetic flux leakage past the susceptor within the chamber; generating a control field from a secondary compensation coil coupled to the chamber, wherein the control field controls the magnetic flux experienced by the cast part; and casting the material within the mold under the controlled degree of flux leakage.