| 摘要 |
PURPOSE:To minimize delay of stopping the operation of a circuit and turn off switching element safely by performing the turning-off at sensing of any failure upon awaiting the switching element current of inverter circuit becoming near the zero phase. CONSTITUTION:When any failure occurs in a cooking apparatus concerned during operation, a failure sensing circuit 17 emits H-level output, while a stopping circuit 18 remains off operation because the output of a heater coil current sensing circuit 23 is at L-level. When the heater coil current approaches near zero and the output of the coil current sensing circuit 23 becomes at H-level, the H-level output of the failure sensing circuit 17 is passed via an AND circuit 24 to the stopping circuit 18, which stops an oscillator 15 giving output, and switching elements 5, 6 are turned off near the zero amperage. To stop the operation of inverter circuit 20 as described in the event of failure, the switching elements 5, 6 are turned off near the zero phase of current, and thereby delay in the operation stop of the inverter circuit 20 is minimized, and destruction due to exceeding the safe operation range at the Off time is prevented. |
