| 摘要 |
PURPOSE: A sine wave obtaining method is provided to enable an inverter voltage change through parameter variation by controlling voltage of an inverter with a digital control signal of a CPU and an obtained sine wave. CONSTITUTION: A CPU(12) detects a phase of a converter to select a frequency value. DC voltage is outputted according to the selected frequency value to be inputted into phase-option D/A converters(14a,14b,14c). The D/A converters(14a,14b,14c) convert the inputted DC voltage into analog quantity of a sine wave via the CPU(12). The sine wave is filtered through a sine wave filter to obtain a complete sine wave. The sine wave is inputted as a reference signal of a comparator, outputted from the inverter, compared with a feedback voltage, and inputted into a PWM controller. AC voltage from the inverter is controlled by the PWM control signal. So, the digital control signal and the obtained sine wave of the CPU(12) can control the voltage of the inverter.
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