| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC/DC converter that enables both of boosting and step-down with a simple circuit configuration.SOLUTION: When a time ratio control amount Ds reaches a first predetermined value at a switching point between boosting and step-down, every period interval determined based on the correlation between a predetermined time ratio control amount Ds and an ON-frequency f, a control circuit 27 performs ON-control on a boosting switching element or step-down switching element which has not been subjected pulse-width modulation control under a state that the ON-period of one of two switching elements connected in series is fixed, and performs OFF-control on the boosting switching element or the step-down switching element under a state that the OFF-period of the other of the two switching elements connected in series is fixed. Then, when the time ratio control amount Ds reaches a second predetermined value, the control circuit 27 exchanges the operations of the boosting switching element and the step-down switching element by each other. Then, when the time ratio control amount Ds reaches a third predetermined value, the control circuit 27 performs the boosting operation by the boosting switching element, and the step-down operation by the step-down switching element.SELECTED DRAWING: Figure 9 |
