| 摘要 |
PURPOSE:To prevent intermittent oscillation of a switching transformer due to reduction of load by using an expansion valve, which is connected to the switching transformer, as a pseudo load when the expansion valve is subjected to off-control. CONSTITUTION:Intermittent oscillation of a switching transformer does not occur in a mode of an expansion valve 4 acting, so that normal control of the expansion valve is effected to cause on-off control of respective inner coils A, B, C and D of the expansion valve 4. When it becomes unnecessary to actuate the expansion valve 4, a pseudo output routine takes effect. In the pseudo output routine, a loading condition of the switching transformer can be set in almost the same manner as at the time of action of the expansion valve 4 by fixing a mode of a step, in which two inner coils close to a step at the time of action of the expansion valve 4 are simultaneously energized, and feeding an electric current to the two inner coils. Accordingly, it is possible to positively prevent intermittent oscillation of the switching transformer due to reduction of load.
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