| 摘要 |
PURPOSE:To maintain a voltage-frequency characteristic optimal for a compressor at all times by taking in a waveform pattern having an optimal voltage- frequency characteristic from a waveform memory based on a signal provided from a voltage detector and then producing and outputting a waveform. CONSTITUTION:Voltage-frequency characteristics of waveform patterns A', B', C' stored in a waveform memory 21 are optimized by the output voltage drop of an inverter 19 due to variation of load on a compressor 1. When the load decreases from a state where a waveform pattern 'B' is outputted within such range of input voltage V to the compressor 1 as V2>=V>=V3, the input voltage V at an inverter output frequency (f) will be V>V1 and the waveform memory 21 modifies the waveform pattern from 'B' to 'A' thus bringing the input voltage V close to a value V0 for an optimal voltage-frequency characteristic. Furthermore, since V2>=V>=V3 is maintained so long as the load maintains constant, the waveform 'A' is sustained and an air-conditioner is operated with the optimal voltage-frequency characteristic regardless of variation of load. |
