| 摘要 |
PURPOSE:To convert an operating frequency into a desired value by obtaining values which are different by an electric angle of 60 deg. with a carrier frequency being constant from data which are stored in a memory circuit for inverter control, and variously combining the obtained values. CONSTITUTION:An AC power source 1 undergoes AC/DC conversion in an AC/DC converter part 4, and DC is obtained. The DC is smoothed in a smoothing capacitor 5. The DC is supplied into a power transistor(Tr) part 6. The bases of the Trs in the power Tr part 6 are switched with a pulse signal from a base driving part 7. A AC power is generated, and a compressor 8 is driven. The data of the pulse signals are outputted from a microcomputer 9 comprising a CPU 10 and a memory 11. In the memory 11, waveforms whose carrier frequency (e.g., 2.6kHz) is constant and whose numbers of carriers are different are stored. The waveforms are separated by every 60 deg. electric angle. The combinations of the waveform data are changed, and the results are outputted. A current conducting pattern is controlled, and generated frequency is changed. In this way, the number of rotation of a compressor motor can be converted into a desired value readily. |
