| 摘要 |
PROBLEM TO BE SOLVED: To provide a controller which can detect the fact that at least one of one or a plurality of A/D conversion circuits is not operating normally, in an air conditioning system where an inverter drives a motor, and can stop the air conditioning system in safety.SOLUTION: A controller 50 includes one or more A/D conversion units 503, 504, and a judgement unit 507. The A/D conversion unit converts a voltage, detected by a voltage detection unit 502 in the circuit of an object device, from an analog value to a digital value. The judgement unit calculates the average value of the digital values after conversion by the A/D conversion unit, and judges that the A/D conversion unit is not operating normally, when the difference between the calculated average value and a reference value based on a predetermined average value of the voltage in a certain period of time is out of a predetermined range.SELECTED DRAWING: Figure 1 |
