Lg Electronics Inc.

Dong Myung Shin

Sung Jin Han

Byeong Wook Park

Eui Sung Kim

Seung Hee Ryu

Min Gi I

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. The microwave oven further comprises a magnetron driver for converting the AC voltage from the inverter into a high-power DC voltage and applying the converted DC voltage to the magnetron, and an inverter control unit for varying the switching frequency of the inverter to prevent overvoltage from being applied to the magnetron.

Inverter microwave oven and method for controlling the same

An induction heating cooker capable of accurately discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, using a phase change in a resonant capacitor voltage of an inverter circuit and a switching pulse signal of the inverter circuit, irrespective of the load of the cooking container, and a method for operating the induction heating cooker. The induction heating cooker includes a power supply for rectifying an AC voltage, filtering the rectified voltage, and supplying the filtered voltage as an input voltage of the induction heating cooker, an inverter circuit for heating a cooking container placed in the induction heating cooker, using the voltage supplied from the power supply, and a container material discriminating unit for discriminating whether a material of the cooking container is magnetic or non-magnetic, based on a resonant capacitor voltage of the inverter circuit and a switching pulse signal of the inverter circuit, upon an initial operation of the induction heating cooker, whereby the cooking container is selectively heated in accordance with the result of the discrimination.

Induction heating cooker and method for operating the same

An inverter circuit of a microwave oven employs a technique which decreases the unit manufacturing cost of production and controls an output of a magnetron correctly. The invert circuit includes a micom outputting a reference voltage preset by a user; an input current detector converting a current provided from the power source to a voltage level; and comparator comparing an output signal of the input current detector with the reference voltage; an integrator increasing or decreasing a level of an output signal for the comparator a trigger circuit connected to the high voltage transformer, and generating a trigger signal; and a PWM controller receiving an output signal of the integrator and an output al of the trigger circuit, for controlling drive of the magnetron.

Inverter circuit of microwave oven

A variable-frequency inverter microwave oven and a method for controlling the same. The inverter microwave oven comprises a magnetron for generating electromagnetic waves, a direct current (DC) voltage generator for rectifying and smoothing a commercial alternating current (AC) voltage, which is an inverter drive voltage, to generate a DC voltage, and a switching device for performing a switching operation based on the DC voltage from the DC voltage generator to generate an AC voltage for the driving of the magnetron. The switching device includes a plurality of switches turned on/off in response to the DC voltage from the DC voltage generator. The microwave oven further comprises a variable-frequency controller for varying a switching frequency of the switching device according to the level of the DC voltage from the DC voltage generator to maintain the AC voltage from the switching device at a constant level, and a magnetron drive voltage generator for converting the AC voltage from the switching device into a high-power DC voltage and transferring the converted DC voltage to the magnetron to drive it. The inverter operation is improved compared with a conventional one and a magnetron drive duration is lengthened, thereby improving heating efficiency and operational reliability of the microwave oven.

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Kyungki-do, South Korea

Dong Myung Shin