SAFETY CIRCUIT FOR DIRECT CURRENT MICROWAVE OVEN AND CONTROL METHOD THEREOF

摘要

PURPOSE: A safety circuit for a microwave oven and a controlling method thereof are provided to regulate DC power by using a switch of small capacity and to detect generation of over current while monitoring a monitor switch for preventing damage on a circuit element. CONSTITUTION: In a closed state of a cooking cavity door, a door detect switch(DSW) and a primary interlock switch(PSW) are switched on by detecting the closed state of the door. By start of a cooking function, a microcomputer(40) turns on a switching transistor(41) for exciting an exciting coil(ICO). A secondary interlock switch(SSW) is switched on according to excited state of the exciting coil. In case of an error in the primary interlock switch and the secondary interlock switch, short state is maintained regardless of opened state of the cooking cavity door. First and second monitor switches(MSW1,MSW2) are switched on according to opened state of the door regardless of short state of the interlock switches. Therefore, a fuse connected to DC is opened. Then, DC is blocked according to the opened state of the fuse regardless of operating state of first and second field effect transistors(FET1,FET2). Therefore, high voltage is not generated while stopping a magnetron.