| 摘要 |
PURPOSE:To obtain stable output voltage even when bus voltage fluctuates by determining the duty ratio of a PWM signal in response to the detecting value of bus voltage and set voltage and driving a switching element for a power inverter based on the duty ratio. CONSTITUTION:A drive circuit 4 outputs a switching signal in accordance with a rectangular wave PWM signal outputted from an AND circuit 10, and drives each switching element 3a-3f for a power inverter 3. A rectangular wave signal from an output terminal 9 is generated in response to goal frequency held by a memory or a register in a microcomputer 7 at that time, and outputted without deforming timing. On the other hand, a duty ratio alters according to the detecting values of goal voltage corresponding to goal frequency and bus voltage acquired through an A/D converter. An output is determined by the duty ratio.
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