Abstract: A gate driver circuit comprises an auxiliary winding, a voltage summer, an auxiliary voltage bus, a gate driver integrated circuit (IC), and a controller. The auxiliary winding is positioned adjacently to the inductor and configured to inductively couple with the inductor. The voltage summer comprises a pair of diodes coupled to the auxiliary winding and a pair of capacitors coupled to the pair of diodes. The auxiliary voltage bus is configured to receive a summed voltage from the voltage summer based on a sum of voltages stored in the pair of capacitors. The gate driver IC is configured to receive a voltage from a positive rail of the auxiliary voltage bus and to output a gate control signal to control a switching device based on the received voltage and based on a pulse signal generated by the controller.

Abstract: A disclosed computer-implemented method for heating an item in a chamber of an electronic oven towards a target state includes heating the item with a set of applications of energy to the chamber while the electronic oven is in a respective set of configurations. The set of applications of energy and respective set of configurations define a respective set of variable distributions of energy in the chamber. The method also includes sensing sensor data that defines a respective set of responses by the item to the set of applications of energy. The method also includes generating a plan to heat the item in the chamber. The plan is generated by a control system of the electronic oven and uses the sensor data.

Abstract: A system for powering a dual magnetron with a dual power supply is disclosed. A first power supply supplies a first voltage to a first magnetron. A second power supply supplies a second voltage to a second magnetron. A balancer circuit controls a drive current for altering a magnetic field of the first magnetron and a magnetic field of the second magnetron to maintain the first voltage and the second voltage at a substantially equal voltage.

Abstract: A feeding coil circuit 120 feeds power by wireless from a feeding coil L2 to a receiving coil L3 based on a magnetic field resonance phenomenon between the feeding coil L2 and receiving coil L3. A transmission power control circuit 200 supplies AC power at a drive frequency to the feeding coil L2 to make the feeding coil L2 feed the AC power to the receiving coil L3. A phase detection circuit 114 measures a phase difference between a current phase of the AC power and a voltage phase thereof. The power transmission control circuit 200 adjusts the drive frequency in accordance with the phase difference. A protection circuit 122 adjusts the phase difference in an increasing direction when the current flowing in the feeding coil L2 increases.

Abstract: The present invention discloses a microbial fuel cell stack, which comprises a plurality of microbial fuel cells and is characterized in that the microbial fuel cell includes a perforated frame, a cathode and an anode, and that the cathode wraps the perforated frame to form an anode chamber, and that the anode is arranged inside the anode chamber. Wires are respectively extended from the cathode and the anode. The microbial fuel cells are connected head to tail sequentially via pipes, and thus the anode chambers thereof interconnect each other. The first microbial fuel cell of the cell stack has a feeding port, and the last one has a discharging port.

Abstract: A high frequency cooking apparatus supplies electric power through a relay contact to a high frequency generator, sets cyclic ON time and OFF time of the relay contact based on set heating time and heating power, and controls the heating power of the high frequency generator. The high frequency cooking apparatus includes a unit for determining whether the time corresponding to the last cycle in the heating time is more than the set ON time of the relay contact, and a unit for increasing the ON time of the relay contact in a cycle just before the last cycle by the ON time of the relay contact in the last cycle and abbreviating the ON time of the relay contact in the last cycle, when the determining unit determines that the time is not more than the set ON time of the relay contact.

Abstract: A microwave irradiation device includes a chamber for accommodating an object to be processed; a plurality of magnetrons for generating microwaves and irradiating the microwaves to the object to be processed in the chamber; and a power supply unit for supplying a pulse-shaped voltage to each magnetron. The power supply unit supplies the pulse-shaped voltage to the magnetrons while preventing temporal overlap of voltage pulses of the pulse-shaped voltage supplied to the respective magnetrons with each other.

Abstract: A system and method for powering a dual magnetron with a dual power supply is disclosed. A first power supply supplies a first voltage to a first magnetron. A second power supply supplies a second voltage to a second magnetron. A balancer circuit controls a drive current for altering a magnetic field of the first magnetron and a magnetic field of the second magnetron to maintain the first voltage and the second voltage at a substantially equal voltage.

Abstract: An RF generator power supply comprises a first switched mode power supply (SMPS) connected in series to a second SMPS by a DC bus. A capacitor is arranged between the outputs of the first SMPS and inputs of the second SMPS to act as a smoothing capacitor for the first SMPS and to supply pulse energy to the second SMPS. The second SMPS has an output connected to an input of a step-up transformer and an output of the step-up transformer is connected to an input of a rectifier connectable to the RF generator. An input of the first SMPS is connectable to a prime power supply to maintain a high power factor with low harmonic content while setting an operating voltage and peak current level for the RF generator. The second SMPS is arranged to feed the step-up transformer and is arranged to operate with a variable duty cycle and/or variable frequency to provide average power control of the RF generator. The second SMPS is rapidly switched off on detection of a power surge through the RF generator.

Abstract: An optimized system and process for heating wood using a microwave heater. The optimized system/process directs microwave energy towards different regions of the wood at different times during heating. In certain situations, microwave energy is introduced into the heater using microwave launchers and the system includes one or more microwave switches that control distribution of microwave energy to the microwave launchers so that two adjacent and/or opposing microwave launchers do not simultaneously introduce microwave energy into the heater. The optimized heating process also includes heating wood using a plurality of sequential heating cycles carried out at different conditions. For example, at least one of the heating cycles can be carried out at a lower input rate of microwave energy and/or at a lower pressure than one of the previous heating cycles.

Abstract: A microwave irradiation device includes a chamber for accommodating an object to be processed; a plurality of magnetrons for generating microwaves and irradiating the microwaves to the object to be processed in the chamber; and a power supply unit for supplying a pulse-shaped voltage to each magnetron. The power supply unit supplies the pulse-shaped voltage to the magnetrons while preventing temporal overlap of voltage pulses of the pulse-shaped voltage supplied to the respective magnetrons with each other.

Abstract: The present invention is directed to improving the conventional high-speed cooking oven based on a combination of hot air impingement and microwave heating by providing a time-dependent spatial variation in the net air impingement and/or net microwave energy applied to the food product in the oven. This is aimed at optimizing heat transfer and microwave efficiencies in a high-speed cooking oven, thereby enabling the oven to deliver an optimal cooking efficiency in comparison to the conventional high-speed cooking oven. In addition, under the present invention, the cooking efficiency may be further optimized by dimensioning the nozzles for hot air impingement to tighten impingement plumes, subject to the space constraint of the oven's cooking chamber, and dimensioning the cooking chamber of the oven in integer multiples of the wavelength of the microwave energy to match the microwave load.

Abstract: The present invention is directed to improving the conventional high-speed cooking oven based on a combination of hot air impingement and microwave heating by providing a time-dependent spatial variation in the net air impingement and/or net microwave energy applied to the food product in the oven. This is aimed at optimizing heat transfer and microwave efficiencies in a high-speed cooking oven, thereby enabling the oven to deliver an optimal cooking efficiency in comparison to the conventional high-speed cooking oven. In addition, under the present invention, the cooking efficiency may be further optimized by dimensioning the nozzles for hot air impingement to tighten impingement plumes, subject to the space constraint of the oven's cooking chamber, and dimensioning the cooking chamber of the oven in integer multiples of the wavelength of the microwave energy to match the microwave load.

Abstract: At least one of a start abnormality detector (31), a temperature abnormality detector (32) and a voltage abnormality detector (33) has a latch inhibiting circuit for inhibiting retention of a detecting state when one of the abnormality detectors detects an abnormality, so that a current abnormality detector (34) can be inhibited from detecting an abnormal input current caused when the oscillation is halted by the abnormality detector. Accordingly, after the abnormality is removed, automatic resetting can be easily accomplished without causing the oscillation to halt as a result of the current abnormality detector detecting the presence of the abnormality. Also, since a power source abnormality detecting circuit (30) is designed in the form of an analog circuit, a low cost can be achieved and the monitoring level can be modified. In addition, the monitoring level associated only with the temperature abnormality occurring in an IGBT element (7) can be modified.

Abstract: A purpose of the present invention is to provide an inverter circuit capable of firmly turning ON IGBTs under limited condition, while a heat loss and noise can be hardly produced in semiconductor switching elements.

Abstract: Disclosed herein are an inverter microwave oven and a method for controlling the same, wherein a switching frequency of an inverter is raised during the initial operation of the microwave oven and then lowered during the normal operation of the oven after the lapse of a predetermined time, so as to prevent overvoltage from being applied to a magnetron, which generates electromagnetic waves, during the initial operation, thereby enhancing durability and operational reliability of the inverter. The inverter microwave oven comprises a rectifier for rectifying and smoothing a commercial AC voltage into a DC voltage. The inverter is adapted to perform a switching operation based on the DC voltage from the rectifier to generate a magnetron drive AC voltage.

Abstract: A low-output microwave lighting system includes: a rectifier for rectifying general AC power inputted through a power source unit and outputting a DC voltage; a power factor compensator for compensating a power factor of the DC voltage inputted through the rectifier; and an inverter circuit unit for receiving the power factor-compensated DC voltage and outputting an AC voltage through frequency varying. 120 Hz of ripple generated at a low output can be reduce, and it is driven at a frequency of 20 KHz or higher, so that a flicker phenomenon does not occur and a volume and weight in facility can be reduced.

Abstract: A microwave oven and a method of controlling the same. The microwave oven is capable of using a plurality of input powers with different frequencies. The microwave oven includes input power sources, an interrupt generation unit and a control unit. The interrupt generation unit generates interrupt signals with different periods according to the frequencies of the input powers. The control unit cumulatively counts pulses generated on the basis of the interrupt signals outputted from the interrupt generation unit, compares the cumulatively counted value with a reference value, and discriminates the frequencies of the input powers depending on the number of instances where the cumulatively counted value is equal to or greater than the reference value.

Abstract: A microwave oven and control method thereof in which the microwave oven has a magnetron initially driven for a preset period of time to generating an output of at least 20% of a rated output of the magnetron when a cooking mode requiring a low output of less than 20% of the rated output of the magnetron is selected. Further, the magnetron performs the cooking mode by generating the low output of less than 20% of the rated output of the magnetron after the initial driving is completed. In this case, the cooking mode requiring the low output can be a thawing mode, a warming mode, etc. Further, the microwave oven of the present invention is an inverter-type microwave oven.

Abstract: A microwave oven and a method of controlling the microwave oven recognize a power supply frequency correctly at a time power is supplied by eliminating the influence of noise. A blocking period is set in which generation of interrupts is deferred until a timer count reaches a predetermined set value, and interrupts are generated if the blocking period elapses. Accordingly, the microwave oven and method of the controlling the microwave oven recognize a power supply frequency without the influence of noise at the time of the power supply, thereby improving reliability of the microwave oven.

Abstract: A microwave oven and a method of controlling the microwave oven recognize a power supply frequency correctly at a time power is supplied by eliminating the influence of noise. A blocking period is set in which generation of interrupts is deferred until a timer count reaches a predetermined set value, and interrupts are generated if the blocking period elapses. Accordingly, the microwave oven and method of the controlling the microwave oven recognize a power supply frequency without the influence of noise at the time of the power supply, thereby improving reliability of the microwave oven.

Abstract: An oven includes both radiant cooking elements and a microwave cooking element that are controlled to reduce cooking time in relation to known radiant ovens. The oven is operable in a speed cooking mode utilizing radiant and microwave cooking elements, a microwave cooking mode utilizing only the magnetron, and a radiant cooking mode utilizing only radiant lamps. In addition, and using a time adjustment algorithm, the total energy into the food is maintained constant for input voltages in a range between about 108 Volts and 132 Volts to suitably cook food even when the input voltage varies.

Abstract: A microwave delivery system for a cooking appliance includes an electronic control unit and a plurality of magnetrons arranged in a spaced relationship for the introduction of various energy fields into an oven cavity. The electronic control unit creates a phase angle shift between each of the microwave energy fields such that a constructive standing wave propagates about the oven cavity. In this manner, localized hot and cold spots, which can detrimentally affect cooking efficiency, are eliminated without the need for mode stirring or turntables. With this system, the total energy delivered to the oven cavity is the combined energy level of the various microwave energy fields.

Abstract: A cooking appliance includes a controller which calculates a desired percentage of hot air convection and microwave energy needed to perform a cooking operation based on selections made by a user through a menu driven display. The display prompts a user for a programming inputs, while also displaying operational information to the user as needed. The programming options enable the user to select between various different cooking operations and also provides for appealing cooking sequences to be stored as cooking recipes. As needed, certain pre-cooking functions are automatically performed, such as heating or cooling of the oven cavity, as needed.

Abstract: A microwave oven comprising a magnetron for generating a high frequency in response to a high voltage, a transformer having primary and secondary coils, the transformer generating the high voltage in a turn ratio of the primary and secondary coils and supplying it to the magnetron, and high-power output switching means for controlling the level of a voltage applied to the primary coil of the transformer. The microwave oven with the high-power output switching means can control its maximum power output level on the basis of an allowable amount of current supplied to a distribution board.

Abstract: A microwave oven includes a hood unit including a hood motor, a magnetron, a transformer having primary and secondary coils, the transformer generating a high voltage in a turn ratio of the primary and secondary coils and supplying the generated high voltage to the magnetron, a hood unit driver for controlling an operation of the hood unit, power output switching means for controlling the level of a voltage to be supplied to the transformer, and a controller for controlling the power output switching means to control the level of the voltage to be supplied to the transformer according to a given operation mode of the hood unit. The power output level of the microwave oven is automatically controlled according to a given operation mode of the hood motor such that the sum of the oven power output and the hood motor power output is constant.

Abstract: A combination convection/microwave oven in which a food product is cooked by microwave energy from a source thereof and by a heated airflow provided by a thermal energy source and a blower. The food product is located in the near field of the microwave energy. The oven includes a controller that operates the thermal energy source and/or the blower according to temperature and or time to improve cooking results. The cooking procedure includes a soak interval during which the thermal energy source, the blower and/or the microwave energy source is turned off, whereby the temperature of the food product is permitted to equilibrate and thereby provide more uniform cooking. The food product may be located directly on the rack or in a microwave transparent or reflective container.

Abstract: A halogen heater control apparatus of a microwave oven and a method thereof, comprises a plurality of halogen heaters which are connected to a utility AC power source, and a halogen heater switching unit. The halogen heater and incrementally alters infrared wavelengths from the halogen heater, and a microcomputer controls the operation of the halogen heater switching unit. The present invention is capable of optimum foodstuff heating and cooking by incrementally altering and controlling the infrared wavelengths from the halogen heater by controlling the utility AC power source duty cycle to the halogen heater in accordance with control signals generated by the microcomputer.

Abstract: A wall-mounted microwave oven and a control method for controlling a hood motor are provided. Here, the wall-mounted microwave oven having a main body forming a cavity for accommodating foods to cook, a casing enclosing the main body and forming a hood duct having an inlet located on a bottom area and an outlet located on an upper area, and a hood fan installed in the hood duct, includes a hood motor driving the hood fan, a first switching portion for switching a current supplied from an external electrical power source to the hood motor, and a microcomputer for controlling the rotational speed of the hood motor by adjusting an on/off time of the first switching portion, based on an external control signal. Thus, since the speed of the hood fan can be varied, conveniences of users can be achieved.

Abstract: A microwave furnace (10) of the type comprising a microwave source (14), coupled to an enclosure for the confinement of microwaves and for containing an object to be heated (12). An independently controllable alternate heating (20) is disposed in relation to the enclosure (12) to provide at least one of radiant and convective heating within the enclosure. The method comprises the steps of energizing the alternate heater (20) so as to generate heat substantially throughout the heating cycle of the furnace (10) and controlling the quanity of heat generated in the object y one or both of the microwaves and the alternate heater so as to provide a desired thermal profile in the object. A temperature sensor to measure the ambient temperature within the enclosure (12) can be provided and control circuit (54) responsive to the sensed temperature controls the quanity of heat generated in the object by the microwaves and the alternate heat so as to provide a desired thermal profile within the object.

Abstract: A method of microwave assisted chemistry is disclosed in which power can be supplied more continuously at preferred power levels to more precisely control or moderate a chemical reaction. The method comprises measuring the duty cycle required to maintain a measured selected parameter of a sample at a predetermined set point while the sample is being exposed to microwave radiation at a first predetermined power level; and moderating the duty cycle and the applied microwave power to increase the on time of the duty cycle while applying power at a second predetermined power level that is sufficient to maintain the sample at the set point using the moderated duty cycle. A corresponding device for microwave assisted chemistry is also disclosed and comprises a cavity for receiving a sample, a waveguide connected to the cavity, a source of microwave radiation connected to the waveguide, and a switching power supply for driving the source of microwave radiation.

Abstract: A wall mounted microwave oven is provided which includes a body forming therein a cavity for accommodating food to be cooked, a magnetron for generating electromagnetic waves to be provided into the cavity, a casing surrounding the body and forming therein a hood duct having an inlet port positioned at the bottom portion of the casing and an outlet port positioned in the upper portion thereof, and a hood fan installed in the hood duct. The wall mounted microwave oven includes a hood sensor for sensing a status that operation of saidhood fan is needed; a first switch for selectively supplying one out of a low-level voltage and a normal voltage to the magnetron, and a controller for controlling the hood fan to operate if a detect signal informing operation of said hood fan is needed is input from the hood sensor and simultaneously controlling the first switch to change the electric power to be supplied to the magnetron from the normal voltage into the low-level voltage.

Abstract: A microwave oven including a defrosting step in which a target which must be heated is irradiated with microwaves which are irregular in terms of time at least when the phase of water in the target is shifted from a solid body to liquid. The microwave oven includes a magnetron for generating microwaves for dielectrically heating a target which must be heated; and a waveguide through which microwaves generated by the magnetron are propagated into a heating chamber, wherein a defrosting process is performed in such a manner that microwaves which are irregular in terms of time and which are in a chaos state are propagated through the waveguide at least when the phase of water in the target is shifted from a solid body to liquid.

Abstract: A magnetron driving control apparatus of a microwave oven and a method thereof by which a magnetron is continuously driven when an output level selectively input by a user belongs to a continuous driving output range, and when the output level exceeds an established time, the magnetron is intermittently driven according to a predetermined period to allow a high voltage transformer to cool by itself during the period the driving of the magnetron is stopped, thereby preventing the high voltage transformer from becoming over-heated and avoiding the high voltage transformer from becoming larger in size to decrease a heat generated by an electric resistance.

Abstract: A wall type microwave oven having a hood device and an output control method thereof are disclosed. The microwave oven includes a first switch section for switching a power supply to a hood motor of the hood device, and a second switch section for switching power supply to a hood lamp of the hood device. A third switch section controls the output of the microwave oven by several stages. A control section switches/controls the third switch section, responsive to a control of the first or second switch section, such that when the microwave oven is operated with the hood motor or said hood lamp, output of the microwave oven is to be a low level.

Abstract: An improved microwave oven equipped with a thermopile sensor and a thawing method using the same which make it possible to detect a food surface temperature by using a thermopile sensor, optimizing the output from the magnetron based on the detected food surface temperature, the size of the food, and the weight of the same, and determining an optimum thawing completion time, thereby obtaining the best thawing condition and significantly reducing the thawing time.

Abstract: Disclosed is a wall mounted microwave oven and a control method therefor including a body forming a cooking cavity for accommodating food to be cooked, a magnetron for generating electromagnetic waves to be provided into the cooking cavity, a casing surrounding the body and forming therein a hood duct having an inlet port positioned at the bottom portion of the casing and an outlet port positioned in the upper portion thereof, and a hood fan installed in the hood duct. The wall mounted microwave oven includes a switch for selecting one out of a low-level voltage and a normal voltage supplied to said magnetron and a controller for controlling the switch in such a manner that the low-level voltage is supplied to the magnetron when the hood fan operates during the magnetron operates with the normal voltage, and simultaneously extending remaining cooking time by a predetermined rate.

Abstract: A microwave oven having a silent cooking mode and a method for operating the microwave oven are disclosed. The microwave oven has a magnetron driving section connected to a secondary winding of a high voltage transformer which receives an external power source via a primary winding thereof. A fan motor ventilates a cooking chamber of the microwave oven and a silent cooking mode selecting key selects the silent cooking mode. Voltage dividing section divides the voltage of the external power source. Switching section supplies the external power source to the fan motor at a normal cooking mode and supplies the external power source of which the voltage is divided by the voltage dividing section to the fan motor at the silent cooking mode. Control section controls the switching section in response to a key signal from the silent cooking mode selecting key. Accordingly, when the user selects the silent cooking mode, a noise generated from the fan motor is reduced remarkably.

Abstract: A method for controlling the microwave feed in a microwave oven, as well as a microwave oven for implementing the method, is disclosed. The power level (P) of the microwaves is controlled by periodic activation or inactivation of the microwave radiation source of the oven during a sequence of control cycles. The oven has a rotary bottom plate carrying the food or dish, and/or a rotary field agitator or aerial. The heating uniformity is improved by adjusting to one another the duration of the control cycle and the revolution time of the bottom plate or of the field agitator or aerial, while taking into consideration the aimed-at power level. In a procedure composed of several steps with different power levels and heating times, the heating times of the different steps are also adjusted to the current control-cycle duration.

Abstract: A method of sterilizing an object having the steps of providing a container with an exterior surface that has a microwave interactive layer and defines an interior space having an initial temperature. An object is then placed within the interior space of the container. Next, the microwave interactive layer is exposed to a first amount of microwaves so that the layer produces heat which raises the temperature within the interior space to a predetermined sterilization temperature. The predetermined sterilization temperature is then maintained within the interior space for an amount of time sufficient to sterilize the object.

Abstract: A microwave oven includes a control section storing a long period pattern in which each period of on and off times is relatively long and a short period pattern in which each period is shorter than that in the long period pattern. A magnetron is controlled to be turned on and off in accordance with either period pattern. The short period pattern is selected when frozen food is thawed. Since the on time in each period of the short period pattern is short, the frozen food is exposed to microwave for a shortened period of time. As a result, unevenness in the thawing is prevented.

Abstract: An electrical control scheme which permits operating power for a microwave oven and a second electrical appliance, such as a refrigerator, to be withdrawn from a single electrical outlet utilizes electrical contacts across which a voltage differential is generated when the oven is in operation and includes wiring connected between the second electrical appliance and the microwave oven. The included wiring conducts electrical power to the second electrical appliance from the power cord of the microwave oven, and the control system further includes a relay having a normally-closed switch.

Abstract: An inductive hot point heating system is regulated or controlled by an oscillation packet control, which uses a symmetrical pattern of complete mains half-waves. The switching takes place in the zero passage and is symmetrical in such a way that there is no d.c. voltage component in the mains. It also contains an optical temperature monitoring of the plate covering the cooking point with an infrared photosensor, which determines the temperature on the basis of its predetermined spectral range.

Abstract: A microwave oven is provided with a removable shelf for dividing a cavity into upper and lower heating zones. Microwave energy from a magnetron is selectively introduced into the upper and lower heating zones to controllably cook separate food items placed therein.

Abstract: Pressed garments are treated with microwaves to activate chemicals without heating the garments, resulting in permanent creases without fabric damage. An apparatus controls the process or curing cross-linking agent impregnated cellulosic fabric with microwave energy. The application allows finite control of the curing process necessary to impart a proper cure of wrinkle free fabric. The garment surface temperatures are continually remotely sensed. The microwave energy is cycled on and off so as not to overcure, avoiding loss of fabric memory and avoiding hot spots or burned fabric.

Abstract: A microwave oven having a pulsed magnetron comprises a timing circuit which determines a cooking time and the pulse duration when the magnetron is pulsed. By means of a time and power setting device, the cooking time and the pulse duration are adapted to a food introduced into the oven chamber. At least one operation parameter affecting the magnetron output is measured and compared with the nominal value of the parameter. In the event of a difference between the measured and the nominal parameter value, the cooking time and/or the pulse duration is/are corrected in relation to the set values in order to eliminate the effect of this difference on the total quantity of energy supplied during cooking.

Abstract: The flow-injection system includes a microwave oven having a flow-through reactor having a flow-through conduit located in windings around a conduit carrier for absorbing microwaves. The windings extend through the radiation cavity of the microwave oven only with a part of their length and transversely to the radiation direction. The microwave oven includes programmable adjusting means for the heating power and the heating period. Thus, in connection with a reduction flow-through reactor and an atomic absorption spectrometer, a determination of hydride formers and mercury in a material sample is possible, independently of the valence state.

Abstract: A microwave sourced heat exchanger in an inverted, truncated frusta-pyramidal or frusta-conical shaped configuration. A heat conductive medium is carried within microwave transparent pipes toward a microwave source having one or more magnetrons along a split path of increasing parameter. The magnetrons sequentially operate in a cyclic pattern such that the respective magnetrons do not operate when their respective operating temperatures exceed their respective maximum safe operating temperatures. The sequential use of multiple magnetrons increases the efficiency and operating life of the magnetrons. The geometrical design of the microwave heat exchanger allows the heat conductive medium anywhere in the conduit to be directly exposed to microwaves. Further, the geometry of the microwave heat exchanger induces a thermal siphon when the heat conductive medium within is exposed to a microwave source placed at the exchanger's broader base.

Abstract: A high frequency heating apparatus such as microwave ovens includes an inverter circuit having a switching element and converting a commercial ac power supply to a high frequency power supply by controlling "on" and "off" periods of the switching element, a magnetron driven by the inverter circuit, a counter cumulatively counting an operating period of time and a deenergization period of time of the magnetron, and a compensator for compensating an "on" period of the switching element based on a count value of the counter so that an input power to the inverter circuit is rendered constant.