| 摘要 |
PROBLEM TO BE SOLVED: To individually operate a plurality of fan motors with three different voltages by using only one DC-DC converter. SOLUTION: The output of a DC power source 1 which outputs a prescribed voltage and the output of a DC-DC converter 2, which converts the output voltage into different voltages are switched by transistors Tr1, Tr2, etc., and applied to fan motors M1, M2, and M3. Three modes are set by mode changeover switches SW1 and SW2, and in the case of a mode 1, the transistors Tr1, Tr3, and Tr5 are turned on/off according to the detected temperatures of in-storage temperature sensors S1, S2, and S3, and the fan motors M1, M2, and M3 are operated at 24 V. Also, in the case of a mode 2, the transistors Tr2, Tr4, and Tr6 are likewise turned on/off and the fan motors M1, M2, and M3 are operated at 12 V. Moreover, in the case of a mode 3, a voltage of 12 V and 24 V are applied alternately. |
