| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital converter capable of taking countermeasures against an abrupt variation in load, power-up, and the like. SOLUTION: The digital converter 1 comprises a step-up chopper 4 equipped with a coil L and a switching element Q, a single phase full-wave rectifier circuit 2 for supplying an input current to the coil L, and a one chip microcomputer 3 performing PWM control to the switching element Q in a predetermined control cycle. Decision is made in a steady state whether the digital converter is in a continuous mode where the input current to the coil L breaks off during a control cycle or in a discontinuous mode where the input current ceases in the way of the control cycle, and the PWM control is performed according to different algorithm based on the decision result. When a DC output voltage Vdc increases and exceeds an upward limit value LMT, the PWM control is stopped and the DC output voltage is dropped quickly. In a subsequent transient state, control on a time calculated by the algorithm is corrected and used. COPYRIGHT: (C)2006,JPO&NCIPI
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